JPH0399480A - Magnetic pulse compression circuit - Google Patents

Abstract

PURPOSE:To enable a discharge load to operate efficiently and to optimize a saturable reactor in saturation operation by a method wherein a saturable reactor is connected in parallel between the ends of the capacitor of a magnetic pulse compression circuit composed of the saturable reactor and the capacitor. CONSTITUTION:A saturable reactor 8, where a core high in rectangularity ratio is used, is set to such a state that the core is previously saturated reverse to a direction in which it is excited by a pulse voltage generated in a capacitor 2. When a switch 4 is closed, energy is transmitted from a capacitor 6-1 to a capacitor 6-2, and a pulse voltage is generated in the capacitor 6-2, and at this point, when the saturable reactor 8 is so designed as to make Ir1 slightly larger than Isr, the saturable reactor 8 is kept in a saturation state or in a state that it is low in impedance so far as a current larger than Ir1 does not flow through it. Therefore, all exciting current flows through the saturable reactor 8 when a saturable reactor 7 is unsaturated, so that it does not flow into a capacitor 6-3. In result, the capacitor 6-3 is not charged and does not increase in voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pulse generator necessary as a power source for a pulsed laser or the like, and particularly to a magnetic pulse compression circuit used for shortening pulses.

(Prior Art) A pulse generator that generates a narrow high voltage pulse is used as a power source for a pulsed laser or the like.

In this type of pulse generator, the electric charge of a capacitor charged to a high voltage is discharged by the conduction operation of a switch, and the pulses generated at this time are supplied to a discharging load such as the above-mentioned pulse laser. Although thyratrons are mainly used as switches, semiconductors such as thyratrons are also used due to issues with switch life and reliability due to the demand for high pulse repetition. However, if short pulses that cannot be switched with semiconductors are required, Cyrisk etc. can switch with a wide width.
A magnetic pulse compression circuit consisting of a saturable reactor and a capacitor is provided at the subsequent stage to shorten the pulse.

Figure 5 shows an example of a conventional short pulse generation circuit, in which 1 is a DC power supply for charging a capacitor, 2 is a switch 4
, a pulse generating circuit consisting of a reactor 5 with an inductance of Ll, a capacitor 6-1, 6-2 with a capacity of Ct and Ct, respectively, a magnetic circuit 3 consisting of a saturable reactor 7 with a saturation inductance of L2, and a capacitor 6-3 with a capacity of C1. The pulse compression circuit 9 is a discharge load such as a pulse laser.

Figure 6 shows the waveforms of each part of the circuit in Figure 5, (A)
~(E) is the capacitor 6-1 voltage Vels and the capacitor 6-2 voltage VC! , capacitor 6-3 voltage vCc
3. Reactor 5 current ■ 1. Saturable reactor 7 current ■
It is 2.

As for the operation of the pulse generator 2, before time t0, the capacitor 6-1 is charged by the DC power supply 1 to its voltage v0, that is, to VCIIIaX. nothing. When the switch 4 is closed, the accelerator 5 and the capacitor 6-1
．． A resonant circuit is formed by 6-2, and the capacitor 6-1
All charges are transferred to the capacitor 6 at tl after half a period of resonance.
-Move to 2. The peak value 11□ of the current I and the pulse width τ are determined by the following equation.

τ13−ωI! cπ ωI where ω1 is the resonant angular frequency of the pulse generation 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 being charged due to the resonance phenomenon, the saturable reactor 7 is in a high impedance unsaturated state so as not to affect the resonance phenomenon. The inductance becomes saturated at t! Make it so that Here LI
>>L, if designed so that the pulse generation circuit 2
The resonant circuit of the capacitors 6-2, 6-3 and the saturable reactor 7 operates without being affected by this. Capacitor 6-2
All of the charges transferred to the capacitor 6-3 at time t2 after half a resonance period of the magnetic pulse compression circuit has elapsed. At this time, the peak value ■1□ of the current ■2 and the pulse width τ2 are expressed by the following equation.

τz 4 □ ωz 3 ω! D CoF In Figure 4, each capacitor 6-1, 6-2, 6-3
Since the capacitances of are normally C, -C, and -C3, their respective voltage peaks are all equal in the resonance phenomenon described above, and from t to t! During this time, the voltage of capacitor 6-1 has moved to capacitor 6-3. Here, τ, and τ8
,■1! 8 is as follows: Since L, >> L, the pulse width decreases and the current peak increases. And time t2
The discharge load 9 is discharged and the charge in the capacitor 6-3 is discharged.

(Problems to be Solved by the Invention) In the circuit operation described above, it is ideal that the saturable reactor 7 of the magnetic pulse compression circuit 3 has an infinite impedance during the unsaturated period, and no current 8 flows at all. However, since the permeability of the saturable reactor core is actually finite, the voltage vc! of the capacitor 6-2. When the current changes as shown in FIG. 7(a), a current flows even during the unsaturated period, that is, from to to tl, as shown in FIG. 7(b). That is, before time 1+, saturable reactor 7
VC on both ends! A voltage of -Vcl is applied, and the magnetic flux φ (N is the number of turns, and φ. is the magnetic flux at to) of the following formula is generated, but since the magnetic permeability is finite, an exciting current flows to generate the magnetic flux of the above formula. It is something that will happen. The magnetic permeability before and after saturation changes at a ratio of tens to hundreds, and although this exciting current is very small compared to the current after saturation, the unsaturated period is considerably longer than the saturated period, so as a result, the time of the exciting current The capacitor 6-3 is charged by the integral value, and as shown in Fig. 7 (
As shown in c), the voltage increases during the unsaturated period of the saturable reactor 7, and reaches vR at time t.

However, this voltage increase causes problems, especially when the laser tube is used as a load.Originally, when generating a laser, an instantaneous pulsed power discharge is required, and in this case C1
From 1 to t! The voltage generated during this period is important, but if the voltage rises before the pulse input, that is, before t2, it will cause a decrease in the laser output due to a decrease in the discharge impedance of the laser tube. Furthermore, if the voltage rise is large, problems such as a change in the timing of discharge of the load or erroneous discharge occur.

Furthermore, if there is a voltage increase as described above at the output end capacitor of the magnetic pulse compression circuit, it will affect the saturation timing of the saturable reactor. The saturation timing of the saturable reactor is determined by the time integral value of the voltage, and in this case, the capacitor 6-
This is the time integral of the value obtained by subtracting the voltages of 2 and 6-3. Although the dominant factor is the pulse voltage generated in capacitor 6-2, the saturable reactor voltage changes due to the influence of the voltage increase in capacitor 6-3 when unsaturated, and there is also the problem that an appropriate saturation point cannot be obtained. . A change in the saturation timing of a saturable reactor in a magnetic pulse compression circuit greatly affects the resonance phenomenon of the circuit, and is directly linked to a decrease in output voltage, a change in the width of generated pulses, and the like. In particular, when magnetic pulse compression circuits are connected in multiple stages, 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 the final output voltage.

The present invention has been made in order to improve the drawbacks of the conventional magnetic pulse compression circuit, and allows the discharge load such as a laser connected as an output to operate efficiently, and saturable reactor saturation operation. The purpose is to provide a magnetic pulse compression circuit that can be optimized.

(Means for Solving the Problems) In a magnetic pulse compression circuit according to the present invention, a saturable reactor is connected in parallel to both ends of a capacitor of a magnetic pulse compression circuit including a saturable reactor and a capacitor.

(Function) In a magnetic pulse compression circuit in which a saturable reactor is connected in parallel to both ends of the capacitor of a magnetic pulse compression circuit consisting of a saturable reactor and a capacitor, the output capacitor when the saturable reactor is unsaturated, which was unavoidable with conventional technology. It becomes possible to suppress voltage rise. As a result, efficient discharge of a discharge load such as a laser connected as a load can be obtained, and it is also possible to optimize the saturation timing of the saturable reactor. When the magnetic pulse compression circuit is configured in several stages, stable saturation operation of each saturable reactor can be obtained, making it possible to efficiently compress pulses.

(Example) An example of the present invention will be described below with reference to the drawings, but the times to, t+, and tt shown in FIG. 5 will be used as they are.

FIG. 1 is a circuit diagram of a short pulse generation circuit equipped with a magnetic pulse compression circuit according to the present invention.

The configuration of the pulse generator 2 in FIG. 1 is the same as that in FIG. 4. The magnetic pulse compression circuit 3 includes a saturable reactor 7, a capacitor 6-3, and a saturable reactor 8 connected in parallel with the capacitor 6-3, and the saturable reactor 8 has different characteristics from the saturable reactor 7. It is something that has.

And 9 is a discharge load such as a pulse laser. Further, as shown in FIG. 2(a), the maximum value of the excitation current during the unsaturated period of the saturable reactor 7 is set to 11.

In Fig. 1, the saturable reactor 8 uses a core with a high squareness ratio, and the core is saturated in the opposite direction to that excited by the pulse voltage generated in the capacitor 6-2. . That is, it is assumed that it is in the region (A) on the core characteristic curve shown in Fig. 3, and in this state,
Therefore, the excitation current is set to IPI. In addition, the saturable reactor 8 is caused by the pulse voltage generated in the capacitor 6-2.
is assumed to be a characteristic that does not saturate.

When the switch 4 becomes conductive, energy is transferred from the capacitor 6-1 to 6-2, and a pulse voltage is generated in the capacitor 6-2. However, the saturable reactor 8 is designed so that the above-mentioned IPI is slightly larger than Isr. (By doing so, the saturable reactor 8 is kept in a saturated state, in other words, in a state with low impedance, unless a current greater than L1 flows. Therefore,
When the saturable reactor 7 is unsaturated, all the excitation current flows to the saturable reactor 8 and does not flow to the capacitor 6-3 as shown in FIG. 2(C). As a result, Figure 2 (
As shown in (d), the capacitor 6-3 is not charged during the unsaturated period of the saturated reactor and does not cause a voltage rise.

Further, the saturable reactor 7 is saturated and the capacitor 6-2.
When resonance by 6-3 starts, the current flowing through the saturable reactor 7 rises rapidly and momentarily exceeds rrt. At this time, for a current larger than Ll, the core of the saturable reactor 8 is no longer saturated, and the pulse voltage generated in the capacitor 6-3 has a characteristic that it is not saturated, so the area shown in FIG. The state of the core changes and maintains a state of high magnetic permeability, that is, high impedance. Here, the state of the core is Hc! If the excitation current at the time is ■, then the saturable reactor 8 has ■□
With the above ■, although the following current flows, capacitor 6-
2 and 6-3 and the resonant current of the saturable reactor 7, connecting the saturable reactor 8 in parallel to the capacitor 6-3 has no effect on this resonance phenomenon. 6-2 to 6-3
The energy transfer to is performed efficiently and the pulse compression operation is completed.

After the pulse compression operation is completed, the device is reset to the position shown in FIG. 3(A) by some method, such as by providing a reset coil, in preparation for the next operation.

In this way, it is possible to configure a magnetic pulse compression circuit that suppresses the voltage rise of the output end capacitor before the saturable reactor is saturated and does not affect the resonance phenomenon after the saturable reactor is saturated. becomes.

Further, since the rise in output capacitor voltage when the saturable reactor is unsaturated can be suppressed, appropriate saturated operation can be obtained. Particularly, when a plurality of stages of magnetic pulse compression circuits of saturable reactors are connected, the resonance phenomena of each stage cooperate and it becomes possible to perform an efficient pulse compression operation. Fourth
The figure shows an example of a short pulse generation circuit equipped with a magnetic pulse compression circuit constructed by connecting a plurality of stages (the figure shows an example of three stages) of magnetic pulse compression circuits according to the present invention. Further, the same effect can be obtained even with 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 construct a magnetic pulse compression circuit that can suppress the output capacitor voltage rise when the saturable reactor is unsaturated, which could not be avoided with the conventional technology. As a result, efficient discharge of a discharge load such as a laser connected as a load can be obtained, and overheating of the load or erroneous discharge can be prevented. Furthermore, since the saturation timing of the saturable reactor can be optimized, a resonance phenomenon is established and efficiency is improved. When the magnetic pulse compression circuit is configured in several stages, stable saturation operation of each saturable reactor can be obtained, making it possible to efficiently compress pulses.

[Brief explanation of drawings]

FIG. 1 is a charge circuit diagram of a magnetic pulse compression circuit according to the present invention, FIGS. 2 and 3 are explanatory diagrams for explaining the operating characteristics of FIG. 1, and FIG. 4 is a diagram showing the operation characteristics of FIG. An electrical circuit of a magnetic pulse compression circuit configured by connecting multiple stages, FIG. 5 is a circuit diagram of a pulse generator for explaining a conventional magnetic pulse compression circuit, and FIGS. 6 and 7 are the same as those shown in FIG. These are voltage and current waveforms for explaining the operation. 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 Fig. 1 Fig. 5

Claims (1)

[Claims] 1. A magnetic pulse compression circuit comprising a saturable reactor and a capacitor, with a saturable reactor connected in parallel to both ends of the capacitor. 2. A magnetic pulse compression circuit formed by connecting the magnetic pulse compression circuit according to claim 1 in a plurality of stages.