JP2856284B2 - 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 kind, a charge of a capacitor filled with a high voltage is discharged by a conductive operation of a switch, 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 a short pulse that cannot be switched by a semiconductor is required, a thyristor or the like performs a wide switch, and after that, a magnetic pulse compression circuit consisting of a saturable reactor and a capacitor is provided to shorten the pulse. Will be

FIG. 5 is an example of a conventional short pulse generating circuit,
DC power source for charging the capacitor, 2 switch 4, the pulse generating circuit reactor 5 which inductance is is L _1, the capacity, each comprising a capacitor 6-1, 6-2 made of C _1, C _2, 3 is magnetic pulse compression circuit consisting of saturated inductance L ₁ becomes saturable reactor 7, the capacitor C ₃ becomes capacitors 6-3, 9 is the discharge load, such as for example pulsed laser.

FIG. 6 shows waveforms at various points in the circuit of FIG.
(A) to (e) are the capacitor 6-1 voltage V _c1 ,
Capacitor 6-2 voltage V _c2 , capacitor 6-3 voltage V
C _c3 , reactor 5 current I ₁ , saturable reactor 7 current I ₂
It is.

The operation of the pulse generator 2, the time t ₀ before the capacitor 6-1 is filled until i.e. V _C1max until the voltage V ₀ by the DC power supply 1. Closing reactor 5 the switch 4 at t _0, the resonant circuit of capacitor 6-1 and 6-2 are formed, the electric charge of the capacitor 6-1 shifts all at half cycle has elapsed after t ₁ of the resonant capacitor 6-2 I do. 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 such that during the period when the capacitor 6-2 is charged by the resonance development, the saturable reactor 7 is in a high impedance unsaturated state so as not to affect the resonance development. Saturate at t ₁ to become inductance L ₂ . Where L ₁ >>
If designed to be L ₂ , the resonance circuit of the capacitors 6-2 and 6-3 and the saturable reactor 7 operates without being affected by the pulse generation circuit 2. Charges the capacitor 6-2 are all transferred to the capacitors 6-3 at time t ₂ the resonant half-period elapsed the magnetic pulse compression circuit. Current at this time
The peak value I _{2max of} I ₂ and the pulse width τ ₂ are as follows.

In FIG. 4, each of the capacitors 6-1, 6-2, 6-3
Is usually C ₁ = C ₂ = C ₃ , the respective voltage peaks are all equal in the above-described resonance development, and from t ₀
voltage of the capacitor 6-1 between t ₂ will be moved to the capacitor 6-3. Here, the relationship between τ ₁ and τ ₂ , I ₁ and I ₂ is Becomes For L ₁ is >> L _2, the pulse width will be reduced current peak is increased. The discharge load 9 is charged in the discharge and the capacitor 6-3 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 The voltage _{Vc2 of} 6-2 is the seventh
Figure (b) a current also flows between Figure 7 when changing from unsaturated period during i.e. t ₀ as shown in (b) of t ₁ as. That is, before time t _1, a voltage of V _c1 −V _c3 is applied to both ends of the saturable reactor 7, and the magnetic flux φ of the following equation However, since the magnetic permeability is finite, the exciting current for generating the magnetic flux of the above equation flows.
The permeability before and after saturation changes at a ratio of several tens to several hundreds, and this excitation current is very small compared to the current after saturation.However, since the unsaturated period is much longer than the saturation period, as a result, the time of the excitation current capacitor 6-3 is charged by the integral value, the voltage to the unsaturated period is increased in FIG. 7 (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. Originally, when generating a laser,
Discharge by instantaneous pulse power is required.
While I during resulting voltage C ₃ to t ₁ from t ₂ it is important, when the voltage rise is in pulse input prior i.e. t ₂ previously, causing a decrease in the laser output caused by discharge impedance drop in the laser tube . In addition, when the voltage rise is large, there occurs a problem that the discharge timing of the load changes or an 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 time of the saturable reactor in the magnetic pulse compression circuit greatly affects the resonance phenomenon of the circuit, and is directly connected 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, which causes problems 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 a magnetic pulse compression circuit according to the present invention, in a magnetic pulse compression circuit including a saturable reactor and a capacitor, a second saturable reactor is connected to both ends of the capacitor of the magnetic pulse compression circuit. When the saturable reactor of the magnetic pulse compression circuit is unsaturated, the second saturable reactor is in a saturated state so as to allow the exciting current of the saturable reactor of the magnetic pulse compression circuit to flow. When the saturated reactor is saturated, the reactor becomes unsaturated and does not reach saturation.

(Operation) In a magnetic pulse compression circuit in which a saturable reactor is connected in parallel to both ends of a capacitor of a magnetic pulse compression circuit composed of a saturable reactor and a capacitor, an output capacitor in the case of saturable reactor unsaturation, which cannot be avoided by the conventional technology. Voltage rise can be suppressed. 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,
The saturable reactor 8 includes a capacitor 6-3 and a saturable reactor 8 connected in parallel with the capacitor 6-3. The saturable reactor 8 has characteristics different from those of the saturable reactor 7. Reference numeral 9 denotes a discharge load such as a pulse laser. Further, as shown in FIG. 2A, the maximum value of the exciting current during the unsaturated period of the saturable reactor 7 is defined as _Isr .

In FIG. 1, a saturable reactor 8 uses a core having a high squareness ratio, and the core is previously saturated in a direction opposite to the direction in which it is excited by the pulse voltage generated in the capacitor 6-2. That is, it is assumed that it is in the area (A) on the core characteristic curve shown in FIG.
the exciting current to I _r1 because in _c1. Further, the saturable reactor 8 is controlled by the pulse voltage generated in the capacitor 6-2.
Is a characteristic that does not saturate.

The capacitors 6-1 to 6-2 by the conduction of the switch 4
In the pulse voltage to the energy goes capacitor 6-2 will occur, I said I _r1 is left to design the saturable reactor 8 to slightly greater than I _sr. By doing so, the saturable reactor 8 is kept in a saturated state, in other words, in a state of low impedance, unless a current _{equal to} or greater than _Ir1 flows. Therefore, the exciting current when the saturable reactor 7 is unsaturated flows entirely through the saturable reactor 8, and as shown in FIG.
-3 does not flow. As a result, Fig. 2 (d)
As shown in (1), the capacitor 6-3 is not charged during the unsaturated period of the saturated reactor and does not cause a voltage rise.

The saturable reactor 7 is a saturable capacitor 6-2,
When the resonance due to 6-3 starts, the current flowing through the saturation reactor 7 rises rapidly and instantaneously exceeds _Ir1 . For more current than this time I _r1, since the core of the saturable reactor 8 is no longer in a saturated state, and is a characteristic which is not saturated by a pulse voltage generated in the capacitor 6-3, the region shown in FIG. 3 (c) The state of the core changes, and the state of high magnetic permeability, that is, high impedance is maintained. In this case, the state of the core of the exciting current o'clock H _c2 and I _r2, the saturable reactor 8 I _r1 or
Although the current less than _Ir2 flows, the capacitors 6-2 and 6
-3 and the resonance current of the saturable reactor 7 are very small, so the saturable reactor 8 is connected to the capacitor 6-3.
Connected in parallel does not affect this resonance development. Therefore, the energy transfer from the capacitor 6-2 to the capacitor 6-3 is performed efficiently, and the pulse compression operation is completed. After the completion of the pulse compression operation, a method shown in FIG.
To the next position to prepare for the next operation.

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 and an efficient pulse compression operation can be performed. FIG. 4 shows an example of a short pulse generating circuit provided with a magnetic pulse compression circuit configured by connecting a plurality of stages (in the figure, three stages are shown) of magnetic pulse compression circuits according to the present invention. The same effect can be obtained by a circuit configuration in which the parallel saturable reactors 8-1 and 8-2 other than 8-3 in FIG. 4 are omitted.

(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 overheating and erroneous discharge of the load can be prevented. Further, since the saturation timing of the saturable reactor can be optimized, a resonance phenomenon is established and the efficiency is improved. 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.

[Brief description of the drawings]

FIG. 1 is a charge circuit diagram of a magnetic pulse compression circuit according to the present invention, FIG. 2 and FIG. 3 are explanatory diagrams for explaining the operation characteristics of FIG. 1, and FIG. FIG. 5 is a circuit diagram of a pulse generator for explaining a conventional magnetic pulse compression circuit, and FIGS. 6 and 7 are diagrams of FIG. 6 is a voltage-current waveform for describing an operation. 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 ... Saturable reactor, 9
…… Discharge load

──────────────────────────────────────────────────続 き Continuation of the front page (72) Koji Ito 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Co., Inc. (72) Eiji Murata 3-3-3 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture No. 22 Kansai Electric Power Co., Inc. (72) Inventor Norio Fujiwara 5-11 Tsuundai, Suita-shi, Osaka (72) Inventor Hiroshi Deguchi 4- 1-40 Higashi, Seiwadai, Kawanishi-shi, Hyogo 1-7-18 Ayanishi, Ayase City (72) Inventor Takuya Hatakeyama 2-48, Higashi Hemi-cho, Yokosuka City, Kanagawa Prefecture (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/097-3/0977 H03K 3 / 537

Claims (2)

(57) [Claims] In a magnetic pulse compression circuit comprising a saturable reactor and a capacitor, a second saturable reactor is connected across the capacitor of the magnetic pulse compression circuit, and the second saturable reactor is connected to the magnetic pulse compression circuit. When the saturable reactor is unsaturated, it is saturated so that the exciting current of the saturable reactor of the magnetic pulse compression circuit flows, and when the saturable reactor of the magnetic pulse compression circuit becomes saturated, it becomes unsaturated and reaches saturation. A magnetic pulse compression circuit characterized in that it is not provided. 2. A magnetic pulse compression circuit comprising the magnetic pulse compression circuit according to claim 1 connected in a plurality of stages.