JP6813382B2 - Pulse power supply - Google Patents

Description

The present invention relates to a pulse power supply device.

A technique for recovering and reusing energy (electric power) used for pulse discharge is known (see, for example, Patent Document 1). In the apparatus described in Patent Document 1, pulse discharge is performed using a pair of electrodes, the energy reflected from the pulse discharge is inverted and recharged in the capacitor, and the recharged energy is used for the next pulse discharge.

Japanese Unexamined Patent Publication No. 2005-185092

After a part of the electric power used for the pulse discharge is recovered by the capacitor in this way, the next pulse discharge is performed by recharging the shortage. However, the amount of power recovered by the capacitor may vary from pulse discharge to pulse discharge. Therefore, if the amount of charge for recharging the capacitor is constant, the electric power may vary with each pulse discharge.

The present invention provides a pulse power supply device capable of reducing variations in electric power for each pulse discharge.

The pulse power supply device according to one aspect of the present invention is a circuit that supplies a first output power for pulse discharge to a pair of electrodes for generating plasma, and is a first output electrically connected in series. A first power storage circuit having a capacitor and a second output capacitor, a first power supply that charges the first output capacitor by the first charging method that charges by continuing to flow the charging current, and a charging current that flows at a predetermined cycle. A second power source for charging the second output capacitor by the second charging method for charging is provided. The first power supply includes a first coil portion provided between one end of the first output capacitor and the other end of the first output capacitor. The second power supply includes a first diode portion arranged so that a current flows from the other end of the second output capacitor toward one end of the second output capacitor. The other end of the first output capacitor and one end of the second output capacitor are connected to each other. The first power storage circuit outputs the power stored in the first output capacitor and the second output capacitor to the first output so as to return from one end of the first output capacitor to the other end of the second output capacitor via a pair of electrodes. It is supplied as electric power. The second power supply charges the second output capacitor after charging the first output capacitor with the first power supply.

In this pulse power supply device, since the first output capacitor and the second output capacitor are connected in series, the charge amount of the first output capacitor and the charge amount of the second output capacitor are the same. Therefore, when either the first output capacitor or the second output capacitor is charged, the charge moves so that the amount of charge of the first output capacitor and the amount of charge of the second output capacitor are the same, and the first output The capacitor and the second output capacitor will be charged. Then, in the pulse power supply device, the electric power stored in the first output capacitor and the second output capacitor is transferred from one end of the first output capacitor to the other end of the second output capacitor via the pair of electrodes. It is supplied as one output power. Therefore, after the first output power is supplied, the power having the opposite polarity to the power before the supply is stored in the first power storage circuit. A first coil portion is provided between one end and the other end of the first output capacitor, and a closed circuit is formed. Therefore, the other end of the first output capacitor is directed toward one end via the first coil portion. The current flows and the first output capacitor is regeneratively charged. A first diode portion is provided between one end and the other end of the second output capacitor, and a closed circuit is formed. Therefore, from the other end of the second output capacitor to one end via the first diode portion. A current flows toward the second output capacitor, and the second output capacitor is regeneratively charged. The amount of electric power regenerated in the first electric power storage circuit in this way may differ for each pulse discharge.

In the pulse power supply device, after the first output capacitor is charged by the first charging method in which charging is performed by continuously flowing the charging current by the first power supply, the charging current is passed by the second power supply at a predetermined cycle. The second output capacitor is charged by the second charging method. In the first charging method, since the first output capacitor is charged by continuing to flow the charging current, it is difficult to finely adjust the power (voltage) charged in the first power storage circuit. On the other hand, in the second charging method, the second output capacitor is charged by repeatedly passing the charging current, so that the first power storage circuit is gradually charged. Therefore, in the second charging method, the power (voltage) charged in the first power storage circuit can be finely adjusted. Therefore, for example, by charging to the vicinity of the desired power by the first charging method and then charging the remaining power by the second charging method, the power to be charged in the first power storage circuit is desired. It becomes possible to match with the electric power. As a result, it is possible to reduce the variation in electric power for each pulse discharge.

The second power source may include an inverter circuit that converts DC power into AC power. The first diode section may be a rectifier circuit that rectifies the AC power converted by the inverter circuit. In this case, by rectifying the AC power generated by the inverter circuit, it is possible to generate a charging current having a predetermined cycle. This makes it possible to realize the second charging method.

The inverter circuit may include a semiconductor switch. In this case, the inverter circuit can be operated at high speed. This makes it possible to shorten the cycle in the second charging method.

The pulse power supply device according to one embodiment is a circuit that supplies a second output power for pulse discharge to another pair of electrodes for generating plasma, and is a third output electrically connected in series. A second power storage circuit having a capacitor and a fourth output capacitor, a third power source for charging the third output capacitor by the first charging method, and a fourth power source for charging the fourth output capacitor by the second charging method. You may prepare. The pair of electrodes may be the center electrode and the first external electrode, and the other pair of electrodes may be the center electrode and the second external electrode. The third power supply may include a second coil portion provided between one end of the third output capacitor and the other end of the third output capacitor. The fourth power supply may include a second diode portion arranged so that a current flows from the other end of the fourth output capacitor toward one end of the fourth output capacitor. The other end of the third output capacitor and one end of the fourth output capacitor may be connected to each other. The second power storage circuit outputs the power stored in the third output capacitor and the fourth output capacitor to the second output so as to return from one end of the third output capacitor to the other end of the fourth output capacitor via a pair of electrodes. It may be supplied as electric power. The fourth power supply may charge the fourth output capacitor after charging the third output capacitor with the third power supply.

In this case, the first output power is supplied to the electrode pair of the center electrode and the first external electrode, and the second output power is supplied to the electrode pair of the center electrode and the second external electrode. Similar to the first power storage circuit, after the second output power is supplied, the second power storage circuit stores power having a polarity opposite to that before the supply. A second coil portion is provided between one end and the other end of the third output capacitor, and a closed circuit is formed. Therefore, the other end of the third output capacitor is directed toward one end via the second coil portion. The current flows and the third output capacitor is regeneratively charged. A second diode portion is provided between one end and the other end of the fourth output capacitor, and a closed circuit is formed. Therefore, the other end of the fourth output capacitor is directed toward one end via the second diode portion. The current flows and the 4th output capacitor is regeneratively charged. The amount of electric power regenerated in the second electric power storage circuit may differ for each pulse discharge. Further, the electric energy of the electric power regenerated in the first electric power storage circuit and the electric energy of the electric power regenerated in the second electric power storage circuit may be different. Even in such a case, the first power storage circuit and the second power storage circuit are charged by charging the remaining power by the second charging method after charging to the vicinity of the desired power by the first charging method. It is possible to match the electric power charged to the desired electric power. Therefore, it is possible to make the first output power and the second output power uniform. As a result, it is possible to reduce the variation in power for each electrode pair in addition to the variation in power for each pulse discharge.

The first power supply and the third power supply may be the same. In this case, the first power storage circuit and the second power storage circuit are charged by the first charging method using one power source. Then, the power charged in the first power storage circuit can be finely adjusted by the second power supply, and the power charged in the second power storage circuit can be finely adjusted by the fourth power supply. Therefore, the number of power supplies included in the pulse power supply device can be reduced, so that the pulse power supply device can be miniaturized.

The second power supply may further include an inductor section for limiting the current flowing through the first diode section. In this case, the current flowing through the first diode portion can be adjusted so as not to exceed the rating of the first diode portion.

According to the present invention, it is possible to reduce the variation in electric power for each pulse discharge.

It is a schematic block diagram of the plasma light source including the pulse power supply device which concerns on one Embodiment. It is sectional drawing of the coaxial electrode along the cross section perpendicular to the central axis. It is a schematic circuit diagram of the pulse power supply device shown in FIG. It is a schematic circuit diagram of the part which supplies output power to a pair of electrodes in the pulse power supply device shown in FIG. It is a timing chart for demonstrating the operation of the pulse power supply device shown in FIG. It is a figure for demonstrating the operation at the time of charging by the 1st charge method of the pulse power supply device shown in FIG. It is a figure for demonstrating the operation at the time of charging by the 2nd charging method of the pulse power supply device shown in FIG. It is a figure for demonstrating the operation at the time of discharge of the pulse power supply apparatus shown in FIG. It is a figure for demonstrating the operation at the time of regenerative charging of the pulse power supply device shown in FIG. FIG. 3 is a schematic circuit diagram of a portion of a modified example of the pulse power supply device shown in FIG. 3 in which output power is supplied to a pair of electrodes.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate description is omitted.

A plasma light source including a pulse power supply device according to an embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram of a plasma light source including a pulse power supply device according to an embodiment. FIG. 2 is a cross-sectional view of a coaxial electrode along a cross section perpendicular to the central axis. The plasma light source 1 shown in FIG. 1 is a facing plasma focus type light source, and is applied to, for example, an exposure apparatus for manufacturing a semiconductor element. The plasma light source 1 is configured to be capable of generating, for example, extreme ultraviolet light (EUV light) having a wavelength of 13.5 nm. The plasma light source 1 enables photolithography to generate fine patterns by generating EUV light. When the plasma light source 1 is used in an exposure apparatus, continuous EUV light is required. Therefore, the plasma light source 1 is required to repeatedly output EUV light emitted in a pulsed manner at a high frequency.

The plasma light source 1 holds a pair of coaxial electrodes 10 that generate plasma, a voltage application device 20 that causes a potential difference between the coaxial electrodes 10, a laser device 30 that irradiates a plasma medium with laser light, and a plasma medium. A plasma medium supply unit 41 is provided.

The pair of coaxial electrodes 10 generate plasma that emits extreme ultraviolet light and confine the plasma. The pair of coaxial electrodes 10 are housed in the chamber 2 and are arranged so as to face each other. The pair of coaxial electrodes 10 are arranged plane-symmetrically with respect to the virtual central surface P extending between them. A certain distance (space) is provided between the pair of coaxial electrodes 10. The chamber 2 is provided with one or more exhaust pipes 3, and a vacuum pump (not shown) is connected to the exhaust pipe 3. The inside of the chamber 2 is maintained at a predetermined degree of vacuum. The chamber 2 is grounded.

As shown in FIGS. 1 and 2, each coaxial electrode 10 includes one center electrode 11, a plurality of external electrodes 12, and one insulator 13. One coaxial electrode 10 and the other coaxial electrode 10 have a common and single central axis AX.

The center electrode 11 is a rod-shaped conductor extending along the central axis AX. The central axis AX is located at the center of the center electrode 11. The center electrode 11 is made of a metal that is not easily damaged by high temperatures. The center electrode 11 is made of a refractory metal such as tungsten and molybdenum. The central axis AX is common to the pair of coaxial electrodes 10. The central axis AX of the center electrode 11 is orthogonal to the above-mentioned central surface P. The tip surface of the center electrode 11 facing the center surface P has a hemispherical shape, for example. The side surface of the center electrode 11 has a conical shape, for example.

The external electrode 12 is a rod-shaped conductor arranged around the center electrode 11. The external electrode 12 is made of a metal that is not easily damaged by high temperatures. The external electrode 12 is made of a refractory metal such as tungsten and molybdenum. The tip surface of the external electrode 12 facing the central surface P may be a curved surface such as a hemisphere or a flat surface.

The external electrode 12 has a predetermined distance from the center electrode 11. The plurality of external electrodes 12 are arranged at equal intervals (that is, rotationally symmetric) in the circumferential direction about the central axis AX. Specifically, the plasma light source 1 is provided with six external electrodes 12. The six external electrodes 12 are arranged at intervals of 60 ° with respect to the central axis AX. The number of the external electrodes 12 is not limited to 6, and may be appropriately set according to the size and shape of the center electrode 11 and the external electrode 12, the distance between them, and the like.

By arranging the plurality of external electrodes 12 around the center electrode 11, an initial discharge can be generated between the center electrode 11 and the external electrode 12. This initial discharge leads to a planar discharge. The planar discharge is also called a current sheet or a plasma sheet.

The insulator 13 is made of, for example, ceramic. The insulator 13 has, for example, a disk shape. The insulator 13 supports each base of the center electrode 11 and the external electrode 12 and defines the distance between them. The insulator 13 electrically insulates the center electrode 11 and the external electrode 12.

The voltage applying device 20 creates a potential difference by applying a discharge voltage having the same polarity or the opposite polarity to each of the coaxial electrodes 10. The voltage application device 20 includes two pulse power supply devices 21 and 21. Details of the pulse power supply device 21 will be described later.

The laser device 30 includes a laser generator 31 that irradiates the plasma medium supply unit 41 with the laser beam 32. The laser generator 31 emits a plasma medium by irradiating the laser beam 32 to generate an initial discharge (that is, planar discharge) of the plasma. The laser generator 31 is, for example, a YAG laser, and outputs a fundamental wave or a double wave of the fundamental wave as a short pulse laser beam for ablation. This laser beam is split into at least two laser beams 32a and 32b by an optical element such as a beam splitter (half mirror) 34 and a mirror 35. The laser beams 32a and 32b irradiate the plasma medium supply unit 41. On the surface of the plasma medium 43 irradiated with the laser beams 32a and 32b, a part of the plasma medium 43 becomes a neutral gas or ions (medium steam MV) which is a plasma medium by ablation, and the center electrode 11 and the external electrode 12 Is released between and.

When the laser beams 32a and 32b are irradiated, the discharge voltage by the voltage applying device 20 is applied to the center electrode 11 and the external electrode 12 of each coaxial electrode 10. When the above-mentioned ablation occurs, a discharge between the center electrode 11 and each external electrode 12 is induced, and further, a planar discharge is formed by this discharge. It is preferable that a plurality of (at least two) laser beams are simultaneously irradiated at intervals in the circumferential direction of the central axis AX. It is desirable that the smaller the number of irradiation points of the laser beam, the more the laser beam is irradiated at a position rotationally symmetric with respect to the center electrode 11. In the plasma light source 1, the laser irradiation points are set at two opposite points (see FIG. 2). Simultaneous irradiation of a plurality of laser beams can be easily achieved by forming a plurality of optical paths having a matching optical path length by using optical elements such as a beam splitter and a mirror.

The plasma medium supply unit 41 holds a plasma medium used for generating plasma light. The plasma medium supply unit 41 has a plasma medium 43 that is a solid or a liquid, and a holding unit 42 that holds the plasma medium 43. The plasma medium 43 can be selected depending on the wavelength of ultraviolet light required. For example, when ultraviolet light of 13.5 nm is required, at least one of lithium (Li), xenon (Xe), tin (Sn) and the like is used as the plasma medium 43. When ultraviolet light of 6.7 nm is required, at least one plasma medium such as gadolinium (Gd) and terbium (Tb) is used.

The plasma light source 1 has two plasma medium supply units 41 for one coaxial electrode 10. The number of plasma medium supply units 41 is not limited to two, and may be appropriately set according to the size and shape of the coaxial electrode 10. The pair of plasma medium supply units 41 are arranged around the coaxial electrode 10.

Next, the details of the pulse power supply device will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic circuit diagram of the pulse power supply device according to the embodiment. FIG. 4 is a schematic circuit diagram of a portion of the pulse power supply device shown in FIG. 3 that supplies output power to a pair of electrodes. Since the pulse power supply devices 21 and 21 have the same circuit configuration, one of the pulse power supply devices 21 will be described here.

The pulse power supply device 21 is a device that supplies output power for pulse discharge between the center electrode 11 and each of the plurality of external electrodes 12 (external electrodes 12a to 12f) arranged so as to be separated from the center electrode 11. Is. In the following description, when distinguishing the elements provided corresponding to the external electrodes 12a to 12f, a to f may be added to the reference numerals representing the elements.

The pulse power supply device 21 includes one terminal 22 and a plurality of terminals 23 (terminals 23a to 23f). The terminal 22 is connected to the center electrode 11 of the coaxial electrode 10, and the terminals 23a to 23f are connected to the external electrode 12 corresponding to each terminal 23. The pulse power supply device 21 supplies output power by applying a discharge voltage so that the potential of the center electrode 11 is higher than the potential of the external electrode 12. The pulse power supply device 21 may supply output power by applying a discharge voltage so that the potential of the center electrode 11 is lower than the potential of the external electrode 12.

The pulse power supply device 21 includes a plurality of power storage circuits 24 (power storage circuits 24a to 24f), a single high voltage power supply 25 (first power supply, third power supply), and a plurality of low voltage power supplies 26 (low voltage power supplies 26a to 26f). ) And the control device 27.

The power storage circuit 24 is a circuit that supplies output power for pulse discharge to a pair of electrodes (center electrode 11 and external electrode 12) for generating plasma. The power storage circuit 24 stores the discharge voltage to be applied to the external electrode 12 as output power. The power storage circuit 24 is provided corresponding to each of the plurality of external electrodes 12. In the present embodiment, since the number of external electrodes 12 is 6, six power storage circuits 24 (power storage circuits 24a to 24f) are provided. For example, the power storage circuit 24a (first power storage circuit) supplies output power for pulse discharge to the center electrode 11 and the external electrode 12a (first external electrode), which are a pair of electrodes for generating plasma. It is a circuit. The power storage circuit 24b (second power storage circuit) supplies output power for pulse discharge to the center electrode 11 and the external electrode 12b (second external electrode), which are another pair of electrodes for generating plasma. It is a circuit. The same applies to the power storage circuits 24c to 24f. Each power storage circuit 24 includes capacitors C1 and C2, diodes D1 and D2, and a voltmeter 28.

The capacitor C1 is charged by the high voltage power supply 25. The capacitor C2 is charged by the low voltage power supply 26. The electric power stored in the capacitors C1 and C2 is output as the output electric power. The diodes D1 and D2 are diodes for preventing backflow of the current I5 (see FIG. 8). One end of the capacitor C1 is connected to the anode of the diode D1. The capacitors C1 and C2 are electrically connected in series. That is, the other end of the capacitor C1 and one end of the capacitor C2 are connected to each other. The other end of the capacitor C2 is connected to the cathode of the diode D2. The cathode of the diode D1 is connected to the center electrode 11 via the terminal 22. The anode of the diode D2 is connected to the external electrodes 12 (external electrodes 12a to 12f) corresponding to each power storage circuit 24 via terminals 23 (terminals 23a to 23f) corresponding to each power storage circuit 24.

That is, the power storage circuit 24a has a capacitor C1 (first output capacitor) and a capacitor C2 (second output capacitor) electrically connected in series, and outputs the power stored in the capacitor C1 and the capacitor C2. It is supplied as (first output power). Specifically, the other end of the capacitor C1 of the power storage circuit 24a and one end of the capacitor C2 of the power storage circuit 24a are connected to each other, and the power storage circuit 24a is paired from one end of the capacitor C1 of the power storage circuit 24a. The output power is supplied so as to return to the other end of the capacitor C2 of the power storage circuit 24a via the electrodes (center electrode 11 and external electrode 12a). The power storage circuit 24b has a capacitor C1 (third output capacitor) and a capacitor C2 (fourth output capacitor) electrically connected in series, and outputs the power stored in the capacitor C1 and the capacitor C2 (third output power). 2 Output power). Specifically, the other end of the capacitor C1 of the power storage circuit 24b and one end of the capacitor C2 of the power storage circuit 24b are connected to each other, and the power storage circuit 24b is separated from one end of the capacitor C1 of the power storage circuit 24b. The output power is supplied so as to return to the other end of the capacitor C2 of the power storage circuit 24b via the pair of electrodes (center electrode 11 and external electrode 12b). The same applies to the power storage circuits 24c to 24f. A pair of one center electrode 11 and one external electrode 12 may be referred to as an electrode pair.

The voltmeter 28 is connected in parallel with the capacitors C1 and C2, and measures the voltage across the capacitors C1 and C2 connected in series. The voltmeter 28 measures the voltage by various methods. The voltage is measured, for example, by using a resistance voltage divider. The voltmeter 28 sets a positive value (positive voltage) when the potential at one end of the capacitor C1 is higher than the potential at the other end of the capacitor C2, and the potential at the other end of the capacitor C2 is higher than the potential at one end of the capacitor C1. The voltage value is output with the case as a negative value (negative voltage). The voltmeter 28 outputs the measured voltage value to the control device 27.

The high-voltage power supply 25 charges the capacitor C1 by the first charging method in which charging is performed by continuously flowing a charging current. The first charging method is also called a chopper method. The high-voltage power supply 25 is commonly used for the power storage circuits 24a to 24f. That is, the high-voltage power supply 25 is the first charging method of the capacitor C1 of the power storage circuit 24a, the capacitor C1 of the power storage circuit 24b, the capacitor C1 of the power storage circuit 24c, the capacitor C1 of the power storage circuit 24d, and the power storage circuit 24e. The capacitor C1 and the capacitor C1 of the power storage circuit 24f are charged at the same time. The high-voltage power supply 25 includes a DC power supply 51, a chopper circuit 52, a transformer 53, a plurality of regeneration control circuits 54, an ammeter 55, and a capacitor C11.

The DC power supply 51 is a power supply for charging the capacitor C11. The DC power supply 51 supplies a DC voltage (for example, 550 V) to the capacitor C11. The capacitor C11 is a power storage unit for supplying the electric power charged by the DC power supply 51 to the capacitor C1.

The chopper circuit 52 is a power conversion circuit, and supplies the electric power stored in the capacitor C11 to the capacitor C1 via the transformer 53. In the present embodiment, the chopper circuit 52 is a voltage reversible chopper circuit, and includes switching elements SW11 and SW12, and diodes D11 to D14.

The switching elements SW11 and SW12 are elements that can switch between electrical opening and closing. That is, it is switched between an on state in which both ends (collector and emitter) of the switching elements SW11 and SW12 are in a conductive state and an off state in which the switching elements are cut off. As the switching elements SW11 and SW12, for example, semiconductor switches such as IGBT (Insulated Gate Bipolar Transistor), MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and bipolar transistor are used. In the example shown in FIG. 4, the switching elements SW11 and SW12 are IGBTs. Drive signals are supplied from the control device 27 to the gates (control terminals) of the switching elements SW11 and SW12, respectively. The switching elements SW11 and SW12 switch between an on state and an off state according to the drive signal output from the control device 27.

The diodes D11 and D12 are freewheeling diodes that are electrically connected in parallel with the switching elements SW11 and SW12, respectively. Specifically, the cathodes of the diodes D11 and D12 are connected to the collectors of the switching elements SW11 and SW12, respectively, and the anodes of the diodes D11 and D12 are connected to the emitters of the switching elements SW11 and SW12, respectively. The diodes D13 and D14 are diodes for regenerating the induced energy of the coil portion L11.

The collector of the switching element SW11 and the cathode of the diode D13 are connected to one end of the capacitor C11, and the emitter of the switching element SW12 and the anode of the diode D14 are connected to the other end of the capacitor C11. The emitter of the switching element SW11 and the cathode of the diode D14 are connected to each other, and the collector of the switching element SW12 and the anode of the diode D13 are connected to each other. The connection point between the emitter of the switching element SW11 and the cathode of the diode D14 and the connection point between the collector of the switching element SW12 and the anode of the diode D13 are connected via the coil portion L11.

The transformer 53 includes a coil portion L11 and a coil portion L12 (first coil portion, second coil portion). The coil portion L11 is provided between one end and the other end of the capacitor C11 via the chopper circuit 52. The coil portion L12 is provided between one end and the other end of the capacitor C1 of each power storage circuit 24 (power storage circuits 24a to 24f) via each regeneration control circuit 54. The coil unit L11 and the coil unit L12 transmit and receive electric power to each other. The coil portion L11 and the coil portion L12 are lead wires wound (wound) around the same core, and are magnetically coupled to each other via the core. The voltage on the primary side is boosted by the transformer 53, and the voltage on the secondary side (for example, 4.9 kV) is supplied.

The plurality of regenerative control circuits 54 are provided corresponding to each of the plurality of power storage circuits 24. Each regeneration control circuit 54 is a circuit for controlling the regeneration of the electric power stored in the capacitor C1 of the corresponding electric power storage circuit 24. The regeneration control circuit 54 includes a diode D15, a diode D16, and a switching element SW13.

The switching element SW13 is an element capable of electrically switching between opening and closing. That is, it is switched between an on state in which both ends (collector and emitter) of the switching element SW13 are in a conductive state and an off state in which the switching element SW13 is in a cutoff state. As the switching element SW13, for example, semiconductor switches such as IGBTs, MOSFETs and bipolar transistors are used. In the example shown in FIG. 4, the switching element SW13 is an IGBT. A drive signal is supplied from the control device 27 to the gate (control terminal) of the switching element SW13. The switching element SW13 switches between an on state and an off state according to a drive signal output from the control device 27.

The diode D15 is a diode for preventing backflow of the regenerative current (current I6 in FIG. 9). The diode D16 is a freewheeling diode electrically connected in parallel with the switching element SW13. Specifically, the cathode of the diode D16 is connected to the collector of the switching element SW13, and the anode of the diode D16 is connected to the emitter of the switching element SW13.

The cathode of the diode D15 is connected to the collector of the switching element SW13, and the emitter of the switching element SW13 is connected to one end of the capacitor C1 of each power storage circuit 24. The anode of the diode D15 is connected to the other end of the capacitor C1 of each power storage circuit 24 via the coil portion L12.

The ammeter 55 is provided in series between the other end of the capacitor C1 of each power storage circuit 24 and the coil portion L12, and measures the current from the other end of the capacitor C1 toward one end. The ammeter 55 measures the current by various methods. The current is measured by, for example, a CT method, a Hall element method, a Rogoski coil method, or the like. The ammeter 55 outputs a value measured as a positive current from the other end to one end of the capacitor C1 of each power storage circuit 24 to the control device 27 as a current value.

Each low-voltage power supply 26 charges the capacitor C2 by a second charging method in which charging is performed by passing a charging current at a predetermined cycle. The second charging method is also referred to as a high frequency charging method. Each low-voltage power supply 26 charges the capacitor C2 after the capacitor C1 is charged by the high-voltage power supply 25. The low voltage power supply 26 is provided corresponding to each of the plurality of external electrodes 12. In the present embodiment, since the number of external electrodes 12 is 6, six low-voltage power supplies 26 (26a to 26f) are provided. The low-voltage power supply 26a (second power supply) charges the capacitor C2 of the power storage circuit 24a by the second charging method after the capacitor C1 of the power storage circuit 24a is charged by the high-voltage power supply 25. The low-voltage power supply 26b (fourth power supply) charges the capacitor C2 of the power storage circuit 24b by the second charging method after the capacitor C1 of the power storage circuit 24b is charged by the high-voltage power supply 25. The same applies to the low-voltage power supplies 26c to 26f. Since the low-voltage power supplies 26a to 26f have the same configuration, the low-voltage power supply 26a will be described here.

The low-voltage power supply 26a includes a DC power supply 61, an inverter circuit 62, a transformer 63, a rectifier circuit 64 (first diode section), a regeneration control circuit 65, an ammeter 66, and a capacitor C21.

The DC power supply 61 is a power supply for charging the capacitor C21. The DC power supply 61 supplies a DC voltage (for example, 100V) to the capacitor C21. The capacitor C21 is a power storage unit for supplying the electric power charged by the DC power supply 61 to the capacitor C2.

The inverter circuit 62 is a circuit that converts the DC power supplied from the capacitor C21 into AC power. In the present embodiment, the inverter circuit 62 is a full-bridge inverter and includes switching elements SW21 to SW24 and diodes D21 to D24.

The switching elements SW21 to SW24 are elements that can electrically switch between opening and closing. That is, it is switched between an on state in which both ends (drain and source) of the switching elements SW21 to SW24 are in a conductive state and an off state in which the switching elements are cut off. As the switching elements SW21 to SW24, for example, semiconductor switches such as IGBTs, MOSFETs and bipolar transistors are used. In the example shown in FIG. 4, the switching elements SW21 to SW24 are N-channel MOSFETs. Drive signals are supplied from the control device 27 to the gates (control terminals) of the switching elements SW21 to SW24, respectively. The switching elements SW21 to SW24 switch between an on state and an off state according to a drive signal output from the control device 27.

The drains of the switching elements SW21 and SW23 are connected to one end of the capacitor C21, and the sources of the switching elements SW22 and SW24 are connected to the other end of the capacitor C21. The source of the switching element SW21 and the drain of the switching element SW22 are connected to each other, and the source of the switching element SW23 and the drain of the switching element SW24 are connected to each other. The connection point between the source of the switching element SW21 and the drain of the switching element SW22 and the connection point between the source of the switching element SW23 and the drain of the switching element SW24 are connected to each other via the coil portion L21.

The diodes D21 to D24 are freewheeling diodes that are electrically connected in parallel with the switching elements SW21 to SW24, respectively. Specifically, the cathodes of the diodes D21 to D24 are connected to the drains of the switching elements SW21 to SW24, respectively, and the anodes of the diodes D21 to D24 are connected to the sources of the switching elements SW21 to SW24, respectively.

The transformer 63 includes a coil portion L21 and a coil portion L22. The coil portion L21 is provided between one end and the other end of the capacitor C21 via the inverter circuit 62. The coil portion L22 is provided between one end and the other end of the capacitor C2 via the rectifier circuit 64 and the regenerative control circuit 65. The coil unit L21 and the coil unit L22 transmit and receive electric power to each other. The coil portion L21 and the coil portion L22 are conducting wires wound around the same core, and are magnetically coupled to each other via the core. The voltage on the primary side is converted by the transformer 63, and the voltage on the secondary side (for example, 100V) is supplied.

The rectifier circuit 64 is a circuit that rectifies the AC power supplied from the inverter circuit 62 via the transformer 63. In the present embodiment, the rectifier circuit 64 is a bridge type full-wave rectifier circuit and includes diodes D25 to D28.

The anode of the diode D25 and the cathode of the diode D26 are connected to each other, and the anode of the diode D27 and the cathode of the diode D28 are connected to each other. The connection point P1 between the anode of the diode D25 and the cathode of the diode D26 and the connection point P2 between the anode of the diode D27 and the cathode of the diode D28 are connected to each other via the coil portion L22. The cathodes of the diodes D25 and D27 are connected to one end of the capacitor C2 of the power storage circuit 24a via the regeneration control circuit 65, and the anodes of the diodes D26 and D28 are connected to the other end of the capacitor C2 of the power storage circuit 24a. There is.

The regeneration control circuit 65 is a circuit for controlling the regeneration of the electric power stored in the capacitor C2. The regenerative control circuit 65 includes a diode D29 and a switching element SW25.

The switching element SW25 is an element capable of electrically switching between opening and closing. That is, it is switched between an on state in which both ends (collector and emitter) of the switching element SW25 are in a conductive state and an off state in which the switching element SW25 is cut off. As the switching element SW25, for example, semiconductor switches such as IGBTs, MOSFETs and bipolar transistors are used. In the example shown in FIG. 4, the switching element SW25 is an IGBT. A drive signal is supplied from the control device 27 to the gate (control terminal) of the switching element SW25. The switching element SW25 switches between an on state and an off state according to a drive signal output from the control device 27. The collector of the switching element SW25 is connected to the cathodes of the diodes D25 and D27, and the emitter of the switching element SW25 is connected to one end of the capacitor C2 of the power storage circuit 24a.

The diode D29 is a freewheeling diode electrically connected in parallel with the switching element SW25. Specifically, the cathode of the diode D29 is connected to the collector of the switching element SW25, and the anode of the diode D29 is connected to the emitter of the switching element SW25.

The ammeter 66 is provided in series between the other end of the capacitor C2, the anode of the diode D26, and the anode of the diode D28, and measures the current from the other end of the capacitor C2 toward one end. The ammeter 66 measures the current by various methods. The current is measured by, for example, a CT method, a Hall element method, a Rogoski coil method, or the like. The ammeter 66 outputs a value measured with the current from the other end to one end of the capacitor C2 as positive to the control device 27 as a current value.

The control device 27 is a controller that controls the high voltage power supply 25 and the low voltage power supply 26. The control device 27 is a computer including, for example, a CPU (Central Processing Unit) and hardware such as a memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The function of the control device 27 is realized by operating each hardware under the control of the CPU based on the computer program stored in the memory.

Specifically, the control device 27 controls the high-voltage power supply 25 and the low-voltage power supply 26 based on the voltage value measured by each voltmeter 28 and the current value measured by each ammeter 55 and 66. For example, the control device 27 charges the capacitor C1 by the first charging method by controlling the switching elements SW11 to SW13. The control device 27 charges the capacitor C2 by the second charging method by controlling the switching elements SW21 to SW25. The control device 27 controls the switching elements SW11 to SW13 to perform a regenerative process of reversing the polarity of the electric power stored in the capacitor C1. The control device 27 controls the switching elements SW21 to SW25 to perform a regenerative process of reversing the polarity of the electric power stored in the capacitor C2. The polarity of the electric power stored in the capacitors C1 and C2 in a state where the potential of the other end of the capacitors C1 and C2 is higher than the potential of one end is reversed by passing a current from the other end of the capacitors C1 and C2 to one end. Charging for making the potential at one end of the capacitors C1 and C2 higher than the potential at the other end is called regenerative charging.

Next, the operation of the pulse power supply device 21 will be described with reference to FIGS. 5 to 9. FIG. 5 is a timing chart for explaining the operation of the pulse power supply device shown in FIG. FIG. 6 is a diagram for explaining the operation of the pulse power supply device shown in FIG. 3 during charging by the first charging method. FIG. 7 is a diagram for explaining the operation of the pulse power supply device shown in FIG. 3 during charging by the second charging method. FIG. 8 is a diagram for explaining the operation of the pulse power supply device shown in FIG. 3 at the time of discharge. FIG. 9 is a diagram for explaining the operation of the pulse power supply device shown in FIG. 3 during regenerative charging.

When the operation of the plasma light source 1 is started, power is not stored in the capacitors C1 and C2 of each power storage circuit 24. Therefore, first, the pulse power supply device 21 charges the capacitor C1. Specifically, when the control device 27 first turns on the switching elements SW11 to SW13, the high-voltage power supply 25 starts charging the capacitor C1 by the first charging method (time t0). Then, as shown in FIG. 6, the current I1 flows from one end of the capacitor C11 through the switching element SW11, the coil portion L11, and the switching element SW12 in order and returns to the other end of the capacitor C11. When a current I1 flows through the coil portion L11, an induced electromotive force is generated in the coil portion L12 by electromagnetic induction, and the coil portion L12, the diode D15, and the switching element SW13 pass in this order from the other end of the capacitor C1 to one end of the capacitor C1. The charging current I2 flows in the return path. By maintaining this state, the charging current I2 continues to flow, and the potential at one end of the capacitor C1 gradually becomes higher than the potential at the other end. In this way, the capacitor C1 is charged by the first charging method.

In the pulse power supply device 21, since the capacitor C1 and the capacitor C2 are connected in series in each power storage circuit 24, the charge amount of the capacitor C1 and the charge amount of the capacitor C2 are the same. Therefore, when either the capacitor C1 or the capacitor C2 is charged, the electric charge moves so that the amount of electric charge of the capacitor C1 and the amount of electric charge of the capacitor C2 are the same, and the capacitor C1 and the capacitor C2 are charged. Become.

While charging the capacitor C1, the control device 27 determines whether or not the voltage value measured by at least one of the voltmeters 28 has reached the switching threshold. This voltage value is a value obtained by measuring the voltage VP of the power storage circuit 24 with the voltmeter 28. The voltage VP is the voltage of the capacitors C1 and C2 connected in series, and specifically, the voltage between one end of the capacitor C1 and the other end of the capacitor C2 with reference to the potential of the other end of the capacitor C2. .. The switching threshold is a voltage threshold for switching from the first charging method to the second charging method. The switching threshold is set to a value lower than the specified value described later, for example, 4.9 kV. This determination is periodically repeated until the voltage value reaches the switching threshold. Then, when it is determined that the voltage value has reached the switching threshold value, the control device 27 turns off the switching elements SW11 to SW13 and stops charging the capacitor C1 by the first charging method (time t1).

Subsequently, the control device 27 turns on the switching element SW25. Then, the control device 27 sets the state of the inverter circuit 62 to the first state in which the switching elements SW21 and SW24 are turned on and the switching elements SW22 and SW23 are turned off, and the state in which the switching elements SW21 and SW24 are turned off. At the same time, the switching elements SW22 and SW23 are periodically switched to the second state in which they are turned on. This switching cycle is, for example, about 50 microseconds.

As shown in FIG. 7, in the first state, the current I3 flows from one end of the capacitor C21 through the switching element SW21, the coil portion L21, and the switching element SW24 in order and returns to the other end of the capacitor C21. In the second state, first, the induced electromotive force of the coil portion L21 causes a current to flow in the coil portion L21 in the same direction as in the first state. Therefore, the current I3 flows from the other end of the capacitor C21 through the switching element SW22, the coil portion L21, and the switching element SW23 in order and returns to one end of the capacitor C21. After that, the induced electromotive force of the coil portion L21 disappears, and a current flows through the coil portion L21 in the opposite direction. That is, the current I3 flows from one end of the capacitor C21 through the switching element SW23, the coil portion L21, and the switching element SW22 in order and returns to the other end of the capacitor C21.

After that, when the inverter circuit 62 is put into the first state, the induced electromotive force of the coil part L21 causes a current to flow through the coil part L21 in the same direction as the second state. Therefore, the current I3 flows from the other end of the capacitor C21 through the switching element SW24, the coil portion L21, and the switching element SW21 in order and returns to one end of the capacitor C21. By repeating such an operation, the inverter circuit 62 converts the DC power stored in the capacitor C21 into AC power. By this operation, an alternating current I3 flows through the coil portion L21. That is, the waveform of the current I3 has a sinusoidal shape.

Then, when an alternating current I3 flows through the coil portion L21, an induced electromotive force of alternating current is generated in the coil portion L22 by electromagnetic induction. Due to this induced electromotive force, in the rectifying circuit 64, the path from the other end of the capacitor C2 through the diode D28, the coil portion L22, the diode D25, and the switching element SW25 in order to return to one end of the capacitor C2, and from the other end of the capacitor C2 The charging current I4 alternately flows through the diode D26, the coil portion L22, the diode D27, and the switching element SW25, and returns to one end of the capacitor C2. The waveform of the charging current I4 has a shape in which the negative half cycle of the sine wave is folded back to the positive side, that is, the positive half cycle of the sine wave is repeated. Assuming that the positive half cycle of the sine wave is one cycle, the cycle of the charging current I4 is half of the switching cycle (cycle of the current I3). That is, the frequency of the charging current I4 is twice the frequency of the current I3. As the charging currents I4 flow alternately, the potential at one end of the capacitor C2 gradually becomes higher than the potential at the other end. In this way, the charging current I4 is repeatedly passed from the other end of the capacitor C2 to one end of the capacitor C2 at a high frequency to charge the capacitor C2 by the second charging method.

While charging the capacitor C2 by the second charging method, the control device 27 determines whether or not the voltage value measured by each voltmeter 28 has reached a specified value. The specified value is a voltage value of the capacitors C1 and C2 when the specified power used for discharging is charged in the power storage circuit 24, and is set to, for example, 5 kV. This determination is periodically repeated until the voltage value reaches the specified value. When it is determined that the voltage value has reached the specified value, the control device 27 turns off the switching elements SW21 to SW25 of the low-voltage power supply 26 corresponding to the power storage circuit 24, and the capacitor C2 by the second charging method is used. Stop charging (time t2). The above process is repeated until charging by all the low voltage power sources 26 is stopped.

At this time, the pulse power supply device 21 supplies output power between the center electrode 11 and the external electrode 12. That is, the pulse power supply device 21 applies a discharge voltage between the center electrode 11 and the external electrode 12. Then, the control device 27 determines whether or not the discharge (radiation of plasma light) has been performed.

Here, the emission of plasma light is performed as follows. With the discharge voltage applied, the laser device 30 irradiates the plasma medium 43 of the plasma medium supply unit 41 with the laser beams 32a and 32b. Immediately after that, an electric discharge occurs between each of the plurality of external electrodes 12 and the center electrode 11 (time t3). As a result, as shown in FIG. 8, the current I5 (discharge current) passes from one end of the capacitor C1 through the diode D1, the center electrode 11, the external electrode 12, and the diode D2 in order and returns to the other end of the capacitor C2. Flows, and a planar discharge distributed over the entire circumference of the center electrode 11 is obtained. In FIG. 8, for convenience of drawing, the path of the current I5 is shown in a simplified manner. Therefore, the current I5 is drawn so as not to pass through the center electrode 11 and the external electrode 12, but the center electrode is actually used. It goes through 11 and the external electrode 12. After that, the planar discharge reaches the tip of the center electrode 11, and the starting point of the discharge current shifts from the side surface of the center electrode 11 to the tip surface. Due to this transfer of current, the plasma that has moved along with the pair of planar discharges converges to a high density and high temperature.

Since this phenomenon proceeds at the coaxial electrodes 10 sandwiching the central surface P (see FIG. 1), the initial plasma is pushed out from one coaxial electrode 10 toward the other coaxial electrode 10. As a result, the initial plasma receives pressure from both directions along the central axis AX (see FIG. 1) and moves to an intermediate position where the coaxial electrodes 10 face each other (that is, the position of the central surface P), and the plasma medium is used as a component. A single plasma is formed. While the planar discharge is occurring, the density and temperature of the plasma increase, and the ionization of ions progresses. As a result, plasma light is emitted from the plasma. Since this plasma light is emitted in a pulsed manner, the series of discharges may be referred to as a pulse discharge.

In this way, plasma light is emitted, and the potential of the other end of the capacitor C2 becomes higher than the potential of one end of the capacitor C1. The control device 27 determines whether or not a discharge (radiation of plasma light) has been performed. For example, the voltage value measured by at least one of the voltmeters 28 is equal to or less than a predetermined voltage threshold value. Determine if it has become low. The voltage threshold value is a voltage value of the power storage circuit 24 capable of determining that the discharge has ended, and is set to, for example, 0V. This determination is repeated periodically until the voltage value becomes lower than the voltage threshold.

Then, when it is determined that the voltage value becomes lower than the voltage threshold value, the control device 27 can determine that the discharge has been performed, and therefore operates the timer (not shown). Then, the control device 27 determines whether a predetermined time has elapsed from the end of the discharge. The predetermined time is a time for preventing re-discharging when the capacitors C1 and C2 are regeneratively charged, and is set longer than the pulse width (time width) of the pulse discharge. The pulse discharge is continued, for example, for about 2 microseconds. This determination is periodically repeated until a predetermined time has elapsed.

Then, when it is determined that the predetermined time has elapsed, the control device 27 turns on the switching element SW13 of each high-voltage power supply 25, starts the regenerative charging of the capacitor C1, and also starts the regenerative charging of each low-voltage power supply 26. Is turned on, and regenerative charging of the capacitor C2 is started (time t4). At this time, the switching elements SW11, SW12, SW21 to SW24 remain in the off state. As a result, as shown in FIG. 9, in the high-voltage power supply 25, the current I6 (regeneration) passes from the other end of the capacitor C1 through the coil portion L12, the diode D15, and the switching element SW13 in order and returns to one end of the capacitor C1. Current) flows. When the current I6 flows from the other end of the capacitor C1 to one end, the electric power charged in the capacitor C1 with a negative voltage is inverted and charged to a positive voltage. When the current I6 flows through the coil portion L12, an induced electromotive force is generated in the coil portion L11 by electromagnetic induction, and the diode D14, the coil portion L11, and the diode D13 pass in this order from the other end of the capacitor C11 to one end of the capacitor C11. A current I7 flows in the return path. As a result, the capacitor C11 is also regeneratively charged.

Further, in each low-voltage power supply 26, a path mainly from the other end of the capacitor C2 through the diode D28, the diode D27, and the switching element SW25 to return to one end of the capacitor C2, and a diode from the other end of the capacitor C2. A current I8 (regenerative current) flows through a path that passes through D26, a diode D25, and a switching element SW25 in order and returns to one end of the capacitor C2. Since the diodes D25 to D28 are the same, ideally, the connection point P1 and the connection point P2 have the same potential. However, in reality, a potential difference occurs between the connection point P1 and the connection point P2 due to variations in the diode or the like. In this case, the current I8 also flows through the coil portion L22.

For example, when the impedance of the diode D26 is larger than the impedance of the diode D28, the potential of the connection point P1 is lower than the potential of the connection point P2. Therefore, the current I8 flows from the connection point P2 through the coil portion L22 to the connection point P1. The current flowing from the connection point P2 to the diode D27 and the current flowing from the connection point P2 to the coil portion L22 are the ratio of the impedance of the diode D27 to the impedance seen from the secondary side of the transformer 63 and the impedance of the diode D25. It is decided according to.

On the other hand, when the impedance of the diode D28 is larger than the impedance of the diode D26, the potential of the connection point P2 is lower than the potential of the connection point P1. Therefore, the current I8 flows from the connection point P1 through the coil portion L22 to the connection point P2. The current flowing from the connection point P1 to the diode D25 and the current flowing from the connection point P1 to the coil portion L22 are the ratio of the impedance of the diode D25 to the impedance seen from the secondary side of the transformer 63 and the impedance of the diode D27. It is decided according to.

When the current I8 flows from the other end to one end of the capacitor C2, the electric power charged in the capacitor C2 with a negative voltage is inverted and charged to a positive voltage. When a current I8 flows through the coil portion L22 from the connection point P2 toward the connection point P1, an induced electromotive force is generated in the coil portion L21 by electromagnetic induction, and the diode D22, the coil portion L21, and the diode D23 are generated from the other end of the capacitor C21. The current I9 flows in the path returning to one end of the capacitor C21. As a result, the capacitor C21 is also regeneratively charged.

After starting the regenerative charging, the control device 27 determines whether or not the regenerative charging is completed. This determination is made, for example, using the time variation of the voltage value measured by at least one of each voltmeter 28. Specifically, the control device 27 determines whether or not the time change of the voltage value is within the predetermined first range. When the regenerative charging is completed, the voltage change of the power storage circuit 24 is almost eliminated, so that the first range is set to the time change of the voltage value at which it can be determined that the regenerative charging is completed. The control device 27 determines that the regenerative charging has been completed if the time change of the voltage value is within the first range, and determines that the regenerative charging has not been completed if it is outside the first range.

Further, the control device 27 may determine whether or not the regenerative charging is completed by comparing the current value measured by the ammeters 55 and 66 of each low-voltage power supply 26 with a predetermined current threshold value. Good. When the regenerative charging is completed, the currents I6 and I8 hardly flow, so the current threshold value is set to a current value at which it can be determined that the regenerative charging is completed. Specifically, the control device 27 determines that the regenerative charging is completed when the current value measured by the ammeters 55 and 66 is smaller than the current threshold value, and the current value measured by the ammeters 55 and 66 is When it is equal to or more than the current threshold value, it is determined that the regenerative charging is not completed.

The control device 27 may determine whether or not the regenerative charging is completed by combining the determination using the voltage value and the determination using the current value. Further, the control device 27 may calculate the power value from the voltage value and the current value, and determine the end of the regenerative charging based on the power value.

This determination is periodically repeated until the regenerative charging is completed. Then, when it is determined that the regenerative charging is completed, the control device 27 turns off the switching element SW25 and turns on the switching elements SW11 and SW12, and starts charging the capacitor C1 by the first charging method. (Time t5). At this time, the switching element SW13 remains in the ON state. Then, the control device 27 determines whether or not the voltage value measured by each voltmeter 28 has reached the switching threshold value. After that, the above operation is repeated.

In this way, each of the plurality of power storage circuits 24 returns the power stored in the power storage circuit 24 from one end of the capacitor C1 to the other end of the capacitor C2 via the center electrode 11 and the corresponding external electrode 12. The output power is supplied by supplying. The control device 27 performs regenerative charging in which the power returned to the capacitor C1 after discharging is returned from the other end to one end by turning on the switching element SW13, and by turning on the switching element SW25, the capacitor after discharging. Regenerative charging is performed to return the power returned to C2 from the other end to one end. Then, the high-voltage power supply 25 and the low-voltage power supply 26 are controlled so that the capacitors C1 and C2 are charged until the power stored in the power storage circuit 24 after the regenerative charging reaches the specified power. At this time, in the first charging method, charging is performed by continuously flowing the charging current I2, so that the voltage VP cannot be accurately adjusted to the specified value. Therefore, after the power storage circuit 24 is charged to some extent by the first charging method, the voltage VP is finely adjusted by the second charging method.

As described above, the pulse power supply device 21 is used for pulse discharge between the center electrode 11 and each of the plurality of external electrodes 12 (external electrodes 12a to 12f) arranged so as to be separated from the center electrode 11. A power storage circuit 24 is provided for each external electrode 12 in order to supply output power. That is, in the pulse power supply device 21, the electrode pair of the center electrode 11 and the external electrode 12a, the electrode pair of the center electrode 11 and the external electrode 12b, the electrode pair of the center electrode 11 and the external electrode 12c, and the center electrode 11 and the external electrode Output power is supplied to the electrode pair with 12d, the electrode pair with the center electrode 11 and the external electrode 12e, and the electrode pair with the center electrode 11 and the external electrode 12f, respectively.

In the pulse power supply device 21, the capacitor C1 of each power storage circuit 24 is simultaneously charged by a single high-voltage power supply 25 in the first charging method in which charging is performed by continuously flowing a charging current, and then by each low-voltage power supply 26. The capacitor C2 of the corresponding power storage circuit 24 is charged by a second charging method in which charging is performed by passing a charging current at a predetermined cycle.

In the first charging method, since the capacitor C1 is charged by continuously flowing the charging current I2, it is difficult to finely adjust the electric power (voltage) charged in the power storage circuit 24. Further, since the high-voltage power supply 25 charges the capacitors C1 of the plurality of power storage circuits 24 at the same time, if the power stored in each power storage circuit 24 is different before the start of charging, each power storage circuit 24 It is not possible to charge so that the electric power stored in is the same. On the other hand, in the second charging method, the capacitor C2 is charged by repeatedly passing the charging current I4, so that the power storage circuit 24 is gradually charged. Therefore, in the second charging method, the power (voltage) charged in the power storage circuit 24 can be finely adjusted. Further, since the low-voltage power supply 26 is provided for each power storage circuit 24, even if the power stored in each power storage circuit 24 before the start of charging is different, it is stored in each power storage circuit 24. The existing power can be charged to the desired power. Therefore, for example, the power stored in the power storage circuit 24 is desired by charging the remaining power by the second charging method after charging to the vicinity of the desired power by the first charging method. It becomes possible to match with the electric power.

Specifically, in the pulse power supply device 21, output power is supplied from one end of the capacitor C1 to the other end of the capacitor C2 via the center electrode 11 and the external electrode 12 in each power storage circuit 24. .. Therefore, after the output power is supplied, each power storage circuit 24 stores power having a polarity opposite to that before the supply. A common coil portion L12 is provided between one end and the other end of the capacitors C1 of the power storage circuits 24a to 24f. As a result, a current I6 flows from the other end of the capacitor C1 toward one end of the capacitor C1 via the coil portion L12, and the capacitor C1 is regeneratively charged.

A rectifier circuit 64 (first) of a low-voltage power supply 26a is arranged between one end and the other end of the capacitor C2 of the power storage circuit 24a so that a current flows from the other end of the capacitor C2 toward one end of the capacitor C2. A diode section) is provided. A rectifier circuit 64 (second) of a low-voltage power supply 26b arranged so that a current flows from the other end of the capacitor C2 toward one end of the capacitor C2 between one end and the other end of the capacitor C2 of the power storage circuit 24b. A diode section) is provided. Similarly, low-voltage power supplies 26c to 26f arranged between one end and the other end of the capacitors C2 of the power storage circuits 24c to 24f so that a current flows from the other end of each capacitor C2 toward one end of the capacitor C2. The rectifier circuit 64 of the above is provided. As a result, in each power storage circuit 24, a current I8 flows from the other end of the capacitor C2 toward one end of the capacitor C2 via the rectifier circuit 64 of the corresponding low-voltage power supply 26, and the capacitor C2 is recharged.

The amount of electric power regenerated in the electric power storage circuit 24 in this way may differ for each pulse discharge. Further, even with the same pulse discharge, the amount of electric power regenerated in the electric power storage circuits 24a to 24f may be different from each other. Even in such a case, in each power storage circuit 24, the power storage circuit 24a is charged by the first charging method to the vicinity of the desired power and then the remaining power is charged by the second charging method. It is possible to match the electric power charged to ~ 24f with the desired electric power. This makes it possible to equalize the output power supplied to each electrode pair for each pulse discharge and to equalize the output power supplied to each electrode pair in the same pulse discharge. As a result, it is possible to reduce the variation in power for each pulse discharge, and it is also possible to reduce the variation in power for each electrode pair in the same pulse discharge.

In the low-voltage power supply 26, the AC power generated by the inverter circuit 62 is rectified by the rectifier circuit 64, so that a charging current I4 having a predetermined cycle is generated. As a result, the second charging method is realized.

In the inverter circuit 62, the switching elements SW21 to SW24 are composed of semiconductor switches. Therefore, the inverter circuit 62 can be operated at high speed. This makes it possible to shorten the cycle of the charging current I4 in the second charging method.

A common high-voltage power supply 25 is provided for each external electrode 12. Therefore, the power storage circuits 24a to 24f are charged by the first charging method using one high-voltage power supply 25. Then, the power charged in the power storage circuits 24a to 24f can be finely adjusted by the low voltage power supplies 26a to 26f. Therefore, since the number of high-voltage power supplies 25 included in the pulse power supply device 21 can be reduced, the pulse power supply device 21 can be miniaturized and the cost can be reduced.

The high-voltage power supply 25 includes a switching element SW13 for electrically connecting or electrically disconnecting one end and the other end of the capacitor C1 via the coil portion L12. An LC circuit is formed by electrically connecting one end and the other end of the capacitor C1 by the switching element SW13 via the coil portion L12. This makes it possible to start the regenerative charging of the capacitor C1. When one end and the other end of the capacitor C1 are always connected via the coil portion L12, the electric power returned to the capacitor C1 is regeneratively charged during pulse discharge, and re-discharge can be performed. There is sex. Therefore, after the pulse discharge is started, the control device 27 turns on the switching element SW13 at a timing later than the time required for the pulse discharge, so that re-discharge can be reliably prevented.

Similarly, each low-voltage power supply 26 includes a switching element SW25 for electrically connecting or electrically disconnecting one end and the other end of the capacitor C2 via the rectifier circuit 64. By this switching element SW25, one end and the other end of the capacitor C2 are electrically connected via the rectifier circuit 64. This makes it possible to start the regenerative charging of the capacitor C2. When one end and the other end of the capacitor C2 are always connected via the rectifier circuit 64, the electric power returned to the capacitor C2 is regeneratively charged during pulse discharge, and re-discharge can be performed. There is sex. Therefore, after the pulse discharge is started, the control device 27 turns on the switching element SW25 at a timing later than the time required for the pulse discharge, so that re-discharge can be reliably prevented.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the pulse power supply device 21 can be used in addition to the plasma light source 1. The pulse power supply device 21 can be applied to a device (a device that requires pulse power with a high repetition cycle) that repeatedly charges one or more electrode pairs in a pulsed manner and applies a voltage to one or a plurality of electrode pairs.

Further, in the above embodiment, the pulse power supply device 21 includes a single high voltage power supply 25, but similarly to the low voltage power supply 26, a plurality of high voltage power supplies provided corresponding to each of the plurality of external electrodes 12. 25 may be provided.

The number of external electrodes 12 is not limited to six. The number of the external electrodes 12 may be one or two or more. The number of terminals 23, the number of power storage circuits 24, and the number of low-voltage power supplies 26 can be appropriately changed according to the number of external electrodes 12. When the number of external electrodes 12 is one, since there is no other electrode pair, the output power supplied to each electrode pair in the same pulse discharge is not uniformed, but is supplied to the electrode pair for each pulse discharge. It is possible to make the output power to be uniform. As a result, it is possible to reduce the variation in electric power for each pulse discharge.

Further, the pulse power supply device 21 may supply output power by applying a discharge voltage so that the potential of the center electrode 11 is lower than the potential of the external electrode 12. In this case, a terminal 22 is provided for each power storage circuit 24, and the cathode of each diode D1 is connected to the corresponding terminal 22. Then, each terminal 22 is connected to an external electrode 12 corresponding to the power storage circuit 24. Further, the pulse power supply device 21 has one terminal 23, and the anode of each diode D2 is connected to the terminal 23. Then, the terminal 23 is connected to the center electrode 11.

The time required for the current I6 to return from the other end of the capacitor C1 to one end (for example, about several hundred μs) is longer than the pulse width of the pulse discharge. Therefore, since the possibility of re-discharging during pulse discharge is low, the high-voltage power supply 25 does not have to include the switching element SW13 and the diode D16. Similarly, each low voltage power supply 26 may not include the switching element SW25 and the diode D29.

In the above embodiment, the voltage VP of the power storage circuit 24 is used to switch from the first charging method to the second charging method, and to stop charging by the second charging method. That is, aligning the voltage VP of each power storage circuit 24 to a specified value is the same as aligning the power stored in each power storage circuit 24 to the specified power used for discharging. Therefore, each power storage circuit 24 may include a power meter that measures the power stored in the capacitor C1 and the capacitor C2. In this case, the control device 27 may switch from the first charging method to the second charging method and stop charging by the second charging method based on the electric power measured by the wattmeter. Further, the control device 27 may end the regenerative charging based on the electric power measured by the wattmeter.

As shown in FIG. 10, each low-voltage power supply 26 may further include an inductor portion L23. The inductor portion L23 is provided between the emitter of the switching element SW25 and one end of the capacitor C2 of the power storage circuit 24. The inductor section L23 is an element for limiting current and suppresses a peak value of current. The inductor section L23 has a predetermined inductance. The inductor portion L23 may be a coil or an electric wire. In this case, the current flowing through the diodes D25 to D28 can be adjusted so as not to exceed the rating of the diodes D25 to D28.

1 Plasma light source 2 Chamber 3 Exhaust pipe 10 Coaxial electrode 11 Center electrode 12, 12a, 12b, 12c, 12d, 12e, 12f External electrode 13 Insulator 20 Voltage application device 21 Pulse power supply device 22 Terminals 23, 23a, 23b, 23c , 23d, 23e, 23f Terminals 24, 24a, 24b, 24c, 24d, 24e, 24f Power storage circuit 25 High-voltage power supply 26, 26a, 26b, 26c, 26d, 26e, 26f Low-voltage power supply 27 Controller 28 Diode meter 30 Laser device 31 Laser generator 32, 32a, 32b Laser light 34 Beam splitter 35 Mirror 41 Plasma medium supply unit 42 Holding unit 43 Plasma medium 51 DC power supply 52 Chopper circuit 53 Transformer 54 Regeneration control circuit 55 Current meter 61 DC power supply 62 Inverter circuit 63 Transformer 64 Rectifier circuit 65 Regeneration control circuit 66 Current meter AX Center axis C1 Condenser C2 Condenser C11 Condenser C21 Condenser D1 Diode D2 Diode D11 Diode D12 Diode D13 Diode D14 Diode D15 Diode D16 Diode D21 Diode D22 Diode D23 Diode D24 Diode D25 Diode D26 Diode D28 Diode D29 Diode L11 Coil part L12 Coil part L21 Coil part L22 Coil part P Central surface SW11 Switching element SW12 Switching element SW13 Switching element SW21 Switching element SW22 Switching element SW23 Switching element SW24 Switching element SW25 Switching element MV Medium steam

Claims (6)

A circuit that supplies a first output power for pulse discharge to a pair of electrodes for generating plasma, and has a first output capacitor and a second output capacitor electrically connected in series. Circuit and
A first power supply that charges the first output capacitor by the first charging method that charges by continuing to flow the charging current, and
A second power source that charges the second output capacitor by a second charging method that charges by passing a charging current at a predetermined cycle, and
With
The first power supply includes a first coil portion provided between one end of the first output capacitor and the other end of the first output capacitor.
The second power supply includes a first diode portion arranged so that a current flows from the other end of the second output capacitor toward one end of the second output capacitor.
The other end of the first output capacitor and one end of the second output capacitor are connected to each other.
The first power storage circuit is stored in the first output capacitor and the second output capacitor so as to return from one end of the first output capacitor to the other end of the second output capacitor via the pair of electrodes. The power is supplied as the first output power,
The second power supply is a pulse power supply device that charges the first output capacitor with the first power supply and then charges the second output capacitor. The second power source includes an inverter circuit that converts DC power into AC power.
The pulse power supply device according to claim 1, wherein the first diode unit is a rectifier circuit that rectifies the AC power converted by the inverter circuit. The pulse power supply device according to claim 2, wherein the inverter circuit includes a semiconductor switch. A second circuit that supplies a second output power for pulse discharge to another pair of electrodes for generating plasma, and has a third output capacitor and a fourth output capacitor electrically connected in series. Power storage circuit and
A third power source that charges the third output capacitor by the first charging method, and
A fourth power source that charges the fourth output capacitor by the second charging method, and
With
The pair of electrodes are a center electrode and a first external electrode.
The other pair of electrodes is the center electrode and the second external electrode.
The third power supply includes a second coil portion provided between one end of the third output capacitor and the other end of the third output capacitor.
The fourth power supply includes a second diode portion arranged so that a current flows from the other end of the fourth output capacitor toward one end of the fourth output capacitor.
The other end of the third output capacitor and one end of the fourth output capacitor are connected to each other.
The second power storage circuit is stored in the third output capacitor and the fourth output capacitor so as to return from one end of the third output capacitor to the other end of the fourth output capacitor via the pair of electrodes. The power is supplied as the second output power,
The pulse power supply device according to any one of claims 1 to 3, wherein the fourth power supply charges the fourth output capacitor after charging the third output capacitor with the third power supply. The pulse power supply device according to claim 4, wherein the first power supply and the third power supply are the same. The pulse power supply device according to any one of claims 1 to 5, wherein the second power supply further includes an inductor portion for limiting the current flowing through the first diode portion.

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