JP2801671B2 - Magnetic pulse compression circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a pulse generator required as a power supply for a pulse laser or the like, and more particularly to a magnetic pulse compression circuit used for shortening a pulse.

(Prior Art) As a power source for a pulse laser or the like, a pulse generator that generates a narrow high-voltage pulse is used. As a pulse generator of this type, a charge of a capacitor charged to a high voltage is discharged by a switch conducting operation, and a pulse generated at this time is supplied to a discharge load such as the pulse laser. Although a thyratron is mainly used as a switch, a semiconductor such as a thyristor is also used due to a problem with the life and reliability of the switch accompanying a demand for higher repetition of pulses. However, when short pulses that cannot be switched by semiconductors are required,
In a thyristor or the like, a wide switch is performed, and a magnetic pulse compression circuit including a saturable reactor and a capacitor is provided in a subsequent stage to shorten a pulse.

FIG. 4 shows an example of a conventional short pulse generating circuit.
DC power source for charging the capacitor, 2 switch 4, a reactor 5 which inductance is L _1, the pulse generating circuit, each capacitor consists of C _1, C ₂ becomes capacitors 6-1 and 6-2, 3 saturated inductance L ₂ becomes saturable reactor 7, the magnetic pulse compression circuit consisting of capacitor C ₃ becomes capacitors 6-3, 10 is a discharge load, such as for example pulsed laser.

FIG. 5 shows waveforms at various points in the circuit of FIG.
(A) to (e) respectively show the capacitor 6-1 voltage V _C1 ,
Capacitor 6-2 voltage V _C2 , capacitor 6-3 voltage V _C3 ,
The reactor 5 current I ₁ and the saturable reactor 7 current I ₂ . The operation of the pulse generator 2, the time t ₀ before the capacitor 6-1 is charged until i.e. V _C1max until the voltage V ₀ by the DC power supply 1. Switch 4 at t ₀
Close the reactor 5, the resonant circuit of capacitor 6-1 and 6-2 are formed, the electric charge of the capacitor 6-1 shifts to all capacitor 6-2 at t ₁ after the elapse half cycle of the resonance. The peak value I _1max and the pulse width τ ₁ of the current I ₁ are determined by the following equation.

Here omega ₁ is the resonance angular frequency of the pulse generating circuit 2, CT is a constant due to the capacitor.

The operation of the magnetic pulse compression circuit 3 is as follows. During a period in which the capacitor 6-2 is charged by the resonance phenomenon, the saturable reactor 7 is in a high impedance unsaturated state so as not to affect the resonance phenomenon, Saturate at t ₁ to become inductance L ₂ . Where L ₁ >>
If designed so that the L _2, without being affected by the pulse generating circuit 2, the capacitor 6-2, 6-3, the resonant circuit of the saturable reactor 7 operates. The electric charge of the capacitor 6-2 is at a time point t ₂ when a half cycle of resonance of the magnetic pulse compression circuit has elapsed.
All of the process goes to the capacitor 6-3. Peak value I _2max and the pulse width tau ₂ of the current I ₂ at this time is as follows.

In FIG. 4, each of the capacitors 6-1, 6-2, 6-
Since the capacitance of 3 is normally C ₁ = C ₂ = C ₃ , the respective voltage peaks in the above-mentioned resonance phenomenon are all equal,
voltage of the capacitor 6-1 between from t ₀ t ₂ is the capacitor 6
-3. Where τ ₁ and τ ₂ , I ₁
The relationship of I ₂ is Becomes For L ₁ is >> L _2, the pulse width will be reduced current peak is increased. Then, electric charge of the capacitor 6-3 to discharge load 10 is discharged at time t ₂ is discharged.

(Problems to be Solved by the Invention) In the above description of the circuit operation, the magnetic pulse compression circuit 3
Of in a saturable reactor 7 unsaturated period, for although the current I ₂ is the infinite impedance is it is ideal not flow at all, it is actually a finite permeability of the saturable reactor core, a capacitor 6-2 voltage V _C2 is the sixth
Figure (b) a current also flows between Figure 6 when changed from unsaturated period during i.e. t ₀ as shown in (b) of t ₁ as. That is, at time t ₁ before the saturable reactor 7 voltage V _c2 -V _c3 is applied across, the following equation flux φ (N is the number of turns and φ ₀ is a magnetic flux at t ₀ ). However, since the magnetic permeability is finite, an exciting current for generating the magnetic flux of the above equation flows.
The magnetic permeability before and after saturation changes at a ratio of several tens to several hundreds, and this exciting current is very small compared to the current after saturation.However, since the unsaturated period is considerably longer than the saturated period, as a result, the time of the exciting current capacitor 6-3 is charged by the integral value, the voltage to the unsaturated period is increased in FIG. 6 (c) as shown in the saturable reactor 7 reaches the V _R at time t _1.

However, this increase in voltage causes a problem particularly when a load is applied to the laser tube. When a laser is originally generated, an instantaneous discharge with pulsed power is necessary. In this case, C ₃
While I during resulting voltage t ₂ from t ₁ is important to the voltage rise in the pulse input prior i.e. t ₂ previously, and decreased discharge impedance of the laser tube, the cause of decrease in the laser output associated therewith Become. In addition, when the voltage rise is large, a malfunction such as erroneous discharge occurs.

Further, if the above-described voltage rise occurs in the output terminal capacitor of the magnetic pulse compression circuit, it affects the saturation timing of the saturable reactor. The saturation timing of the saturable reactor is determined by the time integrated value of the voltage.
It becomes the time integration of the value obtained by subtracting the voltages of -2 and 6-3.
Although the predominant pulse voltage is generated in the capacitor 6-2, there is also a problem that the saturable reactor voltage changes due to the influence of the 6-3 capacitor voltage rise at the time of unsaturated operation, and an appropriate saturation point cannot be obtained. . A change in the saturation magnetism of the saturable reactor in the magnetic pulse compression circuit greatly affects the resonance phenomenon of the circuit, and is directly linked to a decrease in the output voltage, a change in the generated pulse width, and the like. In particular, when a plurality of stages of magnetic pulse compression circuits are connected, the resonance phenomena of the respective magnetic compression circuits cannot be coordinated, resulting in a problem such as a decrease in circuit efficiency and a decrease in final output voltage.

SUMMARY OF THE INVENTION The present invention has been made in order to improve such a drawback of the conventional magnetic pulse compression circuit, in which a discharge load such as a laser connected as an output operates efficiently, and optimization of a saturable reactor saturation operation is performed. It is an object of the present invention to provide a magnetic pulse compression circuit capable of performing the following.

(Means for Solving the Problems) In the magnetic pulse compression circuit according to the present invention, a diode is connected to both ends of a capacitor of the magnetic pulse compression circuit including a saturable reactor and a capacitor such that the positive electrode side is a cathode and the negative electrode side is an anode. , A constant current is supplied in the forward direction of the diode.

(Operation) In a magnetic pulse compression circuit that supplies a constant current in the forward direction of a diode by connecting a diode to both ends of the capacitor so that the positive electrode side is a cathode and the negative electrode side is an anode, a saturable inevitable in the prior art. It is possible to suppress an increase in the output capacitor voltage when the reactor is unsaturated. Thereby, efficient discharge of a discharge load such as a laser connected as a load can be obtained, and the saturation timing of the saturable reactor can be optimized. When the magnetic pulse compression circuit is configured in several stages, stable saturable operation of each saturable reactor is obtained, and pulse compression can be performed efficiently.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.
Times t ₀ , t ₁ , and t ₂ shown in FIG. 5 are used as they are.

FIG. 1 is a circuit configuration diagram of a short pulse generation circuit including a magnetic pulse compression circuit according to the present invention. The pulse generator 2 in FIG. 1 is the same as the configuration in FIG. Regarding the magnetic pulse compression circuit 3, the saturable reactor 7,
It comprises a capacitor 6-3, a diode 8 connected in parallel with the capacitor 6-3 such that the positive electrode side is a cathode and the negative electrode side is an anode, and a current source 9 for flowing a current in the forward direction of the diode 8. Reference numeral 10 denotes a discharge load such as a pulse laser.

The operation of the magnetic pulse compression circuit according to the present invention will be described. Keep electric current I _D0 in the forward direction of the diode 8 in advance by the current source 9. This allows the diode 8
Conducts and enters a low impedance state, so that the forward current I _D0
With the following current, it becomes possible to flow a current from the cathode to the anode. Therefore, by taking slightly larger than the excitation current maximum value I _r of FIG. 6 (b) and the same second view saturable reactor 7, as shown in (a) that said current I _D0, the saturable reactor 7 Unsaturation period (t ₁
All of the exciting current flowing in the (previous) state is bypassed to the diode 8, and does not flow into the capacitor 6-3 as shown in FIG. 2 (d). Thus FIG. 2 (e) time t ₁ earlier as shown in, that it is possible to suppress the voltage rise before saturation of the capacitor 6-3 supersaturation reactor 7.

t ₁ and later, supersaturation reactor 7 is saturated capacitor 6
Current I ₂ becomes into resonance with the -2,6-3 suddenly becomes large. Then, the capacitor 6-3 is charged and the voltage increases. At this time, only I _{D of} I ₂ flows into the current source 9 or the diode 8, but when the current exceeds I _D , the diode 8 is reverse-biased by charging the capacitor 6-3 and cut off State. I _D min of the current I ₂ when the diode 8 is cut off state flows through the current source 9 more can not flow. Here, I _D than the current I ₂ would not have a significant impact because small from t ₁ to the resonance phenomenon of t _2. Therefore, in the t ₂ from saturated after t ₁ of the saturable reactor 7, almost no effect due to attachment diode 8 and a current source 9, the energy transition efficiently rows from the capacitor 6-2 to 6-3 Will be

Thus, before the saturable reactor is saturated,
It is possible to configure a magnetic pulse compression circuit that suppresses a rise in the voltage of the output terminal capacitor and does not affect the resonance phenomenon after the saturation of the saturable reactor.

In addition, since an increase in the output capacitor voltage when the saturable reactor is unsaturated can be suppressed, an appropriate saturation operation can be obtained. In particular, when the magnetic pulse compression circuits of the saturable reactor are connected in a plurality of stages, the resonance phenomena of the respective stages cooperate to enable an efficient pulse compression operation. FIG. 3 shows an example of a short pulse generation circuit including a magnetic pulse compression circuit configured by connecting a plurality of stages (in the figure, three stages are shown) of a magnetic pulse compression circuit according to the present invention.

(Effects of the Invention) As described above, according to the present invention, it is possible to configure a magnetic pulse compression circuit capable of suppressing a rise in the output capacitor voltage when the saturable reactor is unsaturated, which cannot be avoided in the related art. As a result, efficient discharge of a discharge load such as a laser connected as a load can be obtained, and it is possible to prevent mismatching and erroneous discharge due to low impedance of the load. Further, since the saturation timing of the saturable reactor can be optimized, a resonance phenomenon is established and the efficiency is improved. If the magnetic pulse compression circuit is configured in several stages,
A stable saturated operation of each saturable reactor is obtained,
Pulse compression can be performed efficiently. A similar effect can be obtained even in a circuit configuration in which diodes and current source devices other than 8-3 and 9-3 in FIG. 3 are omitted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electric circuit diagram of a magnetic pulse compression circuit according to the present invention; FIG. 2 is a voltage-current waveform for explaining the operation characteristics of FIG. 1; FIG. 1 is an electric circuit diagram of a magnetic pulse compression circuit constituted by connecting a plurality of stages, FIG. 4 is a circuit diagram of a pulse generator for explaining a conventional magnetic pulse compression circuit, FIG. 5, FIG. Is a voltage / current waveform for explaining the operation of FIG. DESCRIPTION OF SYMBOLS 1 ... DC high voltage power supply 2 ... Pulse generation circuit 3 ... Magnetic pulse compression circuit 4 ... Switch 5 ... Reactor 6 ... Capacitor 7 ... Saturable reactor 8 ... Diode, 9 ... Current source 10 …… Discharge load

Continuation of the front page (72) Inventor Koji Ito 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Co., Inc. (72) Eiji Murata 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Norio Fujiwara 5-11 Tsuundai, Suita-shi, Osaka 1-7-18 (72) Inventor Takuya Hatakeyama 2-48 Higashi-Hemicho, Yokosuka City, Kanagawa Prefecture (56) References JP-A-62-108588 (JP, A) JP-A-62-152189 (JP, A) JP-A-63-229784 (JP, A) JP-A-63-229788 (JP, A) JP-A-1-132185 (JP, A) JP-A-2-105480 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) H01S 3/097 H03K 3/537

Claims (2)

(57) [Claims] A diode is connected to both ends of a capacitor of a magnetic pulse compression circuit comprising a saturable reactor and a capacitor so that a positive electrode side is a cathode and a negative electrode side is an anode,
A magnetic pulse compression circuit comprising an auxiliary power supply for supplying a constant current in a forward direction of the diode. 2. A magnetic pulse compression circuit comprising the magnetic pulse compression circuit according to claim 1 connected in a plurality of stages.