JP2820973B2 - Corrugated line - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a pulse waveform shaping line used for a pulse circuit, and is used for a pulse circuit of a power supply unit for generating a particle beam, a free electron laser, or the like. .

2. Description of the Related Art Waveform shaping lines used in these pulse circuits are used to form a very steep rectangular wave having, for example, an impedance of 1 to 50Ω, a voltage of 0.1 to 10 MV, and a pulse width of 10 to 100 ns.

Such a waveform is usually a rectangular wave according to the so-called traveling wave theory using a waveform shaping line made of a coaxial cylinder or a parallel plate. FIG. 3 shows an embodiment of a waveform shaping line using these.

The high-voltage pulse power supply 2 is a power supply unit that supplies electric charges to the waveform shaping line 1 in a pulsed manner by closing the first switch 3. The corrugated line 1 comprises a coaxial cylindrical low voltage side outer electrode 4 and a high voltage side inner electrode 5, between which a dielectric 6
There is filled, the equivalent circuit to form a surge impedance Z _1. The inner electrode 5 and the first terminal 8 or 8a are electrically connected via the insulator 7 and are kept airtight by a method (not shown). Similarly, the external electrode 4 is electrically connected to the second terminal 9 or 9a or via an insulator 7 and is kept airtight by a method (not shown).

The first terminal 8 and the second terminal 9 form a closed circuit with the first switch 3 and the pulse power supply 2. The first terminal 8a and the second terminal 9a, the load is the inductance 11 and the impedance Z ₂ is established to the second switch 10 and the circuit 12
And constitute a closed circuit.

Now, to describe the operation, close the first switch 3, the pulse to supply the charge from the pulse power source 2 to the waveform shaping line 1 of the surge impedance Z _1, the space between the inner electrode 5 and outer electrode 4 It charges the capacitor formed by charging the dielectric 6, when the voltage reaches the vicinity of the maximum value, via an inductance 11 closes the second switch 10 and supplies the charge to the load 12 of impedance Z _2.

Since the voltage applied to the load 12 is normally impedance-matched so that Z ₂ = Z ₁ , the waveform shaping line 1
Is applied to the load 12, and the pulse width of the rectangular wave becomes τ proportional to the length of the waveform shaping line. This is represented by the following equation.

ε ₅ : dielectric constant of dielectric c: speed of light l: length of waveform forming line r ₁ : radius of inner electrode r ₂ : radius of outer electrode Therefore, when a rectangular wave with a long pulse width is required,
A method of selecting the dielectric 6 having a large relative dielectric constant or increasing the length of the waveform-shaped line 1 is adopted. In addition to the selection of the dielectric 6, the impedance of the outer electrode 4 and the inner electrode 5 is set.
The design was made by appropriately selecting the ratio of the radii.

Problems to be Solved by the Invention As described above, it is difficult to realize a rectangular wave having a high impedance and a long pulse width according to the concept of the conventional waveform shaping line. For example, when it is desired to obtain a rectangular wave having a voltage of 1 MV impedance Z ₁ = 50Ω and a pulse width τ = 300 ns in the waveform forming line 1, an insulating oil having a small relative dielectric constant is added to the dielectric 6 having excellent withstand voltage characteristics ( ε ₅
Table 2.2 shows the design dimensions of the corrugated line 1 when large pure water (ε ₅ = 80) is used.

The surface maximum potential gradient of the inner electrode 5 was set to 150 kV / cm.

As can be seen from this table, in the case of insulating oil, the length was too long, and in the case of pure water, the diameter was too large, resulting in an unrealistic shape.

Means for Solving the Problems The present invention provides a multi-stage pulse forming network circuit (hereinafter, referred to as a multi-stage circuit) in which a waveform shaping line is divided and replaced with a plurality of capacitors as lumped constants, and each of them is connected by a coil. A PFN circuit) is formed, and by selecting the inductance values of the capacitor and the coil to appropriate values, a method of determining the impedance and the pulse width can be used to form a realistic waveform-shaped line.

That is, in a waveform shaping line that receives a supply of electric charge from a pulse power supply and generates a rectangular wave, a cylindrical outer electrode such as a cylinder or a square, and an appropriate distance from the outer electrode inside the outer electrode. A pulse forming network circuit is formed by filling a dielectric between a plurality of inner electrodes arranged in the longitudinal direction so as to be aligned with each other, forming a capacitor, and coupling the respective inner electrodes with a coil. This is a waveform shaping line characterized by having the above configuration.

Embodiment FIG. 1A shows an embodiment. Components having the same functions as those of the above-described conventional FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted. The inner electrode 5a and the coil 13 fixed by a method not shown are divided into a required number according to a required rectangular wave shape, and are electrically connected in series between the third terminals 14 and 14a. Configure the circuit.

Further, the first terminal 8, the third terminal 14, and the insulator 7 and the first terminal 8a, the third terminal 14a, and the insulator 7 are hermetically held by a method (not shown) so that the first terminal 8 And the third terminal
14 is also electrically connected to the first terminal 8a and the third terminal 14a.

Now, to configure the impedance Z ₁ of the PFN circuit took matching the impedance Z ₂ of the load 12, it is necessary to satisfy the following equation.

L: Synthetic inductance of waveform shaping line C: Synthetic capacitance of capacitor formed between inner electrode and outer electrode of waveform shaping line Further, pulse width τ is expressed by the following equation.

Now, the values of L and C are divided into n stages according to the shape of the required rectangular wave.
L and the capacitance ΔC of the unit capacitor are represented by the following equations.

Next, the operation will be described.

Closing the first switch 3, a pulsed manner to supply charge to the waveform shaping line 1 of the impedance Z ₁ from the pulse power supply 2, the dielectric 6 was filled in a space between the outer electrode 4 and a plurality of inner electrodes 5a Each of the unit capacitors consisting of
When the voltage reaches the vicinity of the maximum value, the second switch 10 is closed to supply the charge to the load 12 via the inductance 11. FIG. 1 (b) shows an equivalent circuit of the waveform shaping line of FIG. 1 (a). As can be seen from this circuit, this is a PFN circuit that generates a general rectangular wave. Therefore, since the voltage applied to the load 12 is usually determined to be Z ₂ = Z ₁ , half of the voltage charged in the waveform shaping line 1 is given to the load 12, and the pulse width τ of the rectangular wave is Given by

Now, under the same conditions according to the above-described example, that is, when the operating voltage of the waveform forming line 1 is 1 MV, the impedance Z ₁ = 50Ω, and the pulse width τ = 300 ns (the surface maximum potential gradient of the inner electrode 5a is 1
50kV / cm) is shown for each part.

-Synthetic capacitance of the waveform shaping line C = 3nF-Synthetic inductance of the waveform shaping line L = 7.5μH When the number of stages of the PFN circuit is n = 5-Capacitance of the unit capacitor ΔC = 600pF-Unit inductance ΔL = 1.5 The specific dimensions of the wave-shaped line 1 when pure water is used for the μH dielectric 6 are as follows.

・ The outer diameter of the inner electrode is 10.8cm ・ The inner diameter of the outer electrode is 37.1cm ・ The length of one inner electrode is 16.7cm Therefore, since n = 5 stages, five inner electrodes are required and ΔL = 1.5μH unit coil Five are required, but the total length of the corrugated line is 1.
It can be less than 5m.

That is, as apparent from comparison with Table 1, the dimensions and the diameter direction of the corrugated line 1 are the same as those in the case where the insulating oil is used, but the length is very short. Can be made.

Now, FIG. 1A shows a coaxial cylindrical shape, but FIG. 2 shows another embodiment.

FIG. 2 is based on a rectangular tank shape. The components having the same function are denoted by the same reference numerals, and the operation is the same, so that the description is omitted.

Next, another application example of the present invention will be described. Until now, PFN
The values of multiple capacitors and the inductance of the circuit were all the same in order to form a flat rectangular wave, but one or both of the values of each of the capacitors and each of the inductances differed appropriately from place to place If the value is set to a value, the tail of the rectangular wave can be intentionally raised or lowered, so that an arbitrary waveform can be easily formed. For example, in FIG. 1 (b), the values of the plurality of unit capacitors ΔC are all the same, and the values of the plurality of unit inductances ΔL are decreased near the power supply and gradually increased as the load approaches. If you go,
The tail of the rectangular wave generated in the load can be lifted. Since the change of the inductance value is generally easier than the change of the capacitor value, this method is an effective method for adjusting the output waveform.

According to the present invention, it is possible to form a high-impedance, long-pulse-width rectangular wave in a conventional high-voltage rectangular-wave generator without changing the concept of the waveform shaping line technology so much. In addition to the structural dimensions, it is possible to appropriately select gas, oil, pure water, and other insulators as the dielectric to be filled. Also, the coil can be made into any shape and number of turns using wires, rods, pipes, plates, etc., so by properly selecting the inductance of the coil and the capacitance of the capacitor, the impedance can be several hundred Ω, pulse It is possible to produce a practical small-sized waveform-shaped line having a width of several μs, which is of great practical value.

[Brief description of the drawings]

FIG. 1 is an embodiment of a waveform-shaped line according to the present invention, in which (a) is an explanatory diagram, (b) is an equivalent circuit diagram, and FIG. 2 is a perspective cut-away view of another embodiment of the waveform-shaped line according to the present invention. FIGS. 3A and 3B are explanatory diagrams of a conventional waveform shaping line. 1: Waveform shaping line, 2: Pulse power supply 4: Outer electrode, 5, 5a: Inner electrode, 6: Dielectric 13: Coil

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03K 3/53 H03K 3/543 H03K 3/55 H03K 3/57 5H790 KK01

Claims (1)

(57) [Claims] 1. A waveform shaping line which receives a charge from a pulse power supply to generate a rectangular wave, and has a cylindrical outer electrode having a proper distance from the outer electrode inside the outer electrode. A dielectric is filled between a plurality of inner electrodes arranged in a longitudinal direction so as to be separated from each other to form a capacitor, and each of the inner electrodes is connected with a coil to form pulse forming. -A waveform shaping line characterized by comprising a network circuit.