JPH04296114A - Pulse generator - Google Patents

Abstract

PURPOSE:To efficiently send a square pulse having a high voltage and a fast rising and a wide pulse width to a high impedance load. CONSTITUTION:A capacitor 6 is connected to a charging circuit 2. The high voltage terminal of the capacitor 6 is connected to the input side terminals 21a, 22a of a center conductor of two pulse shaping lines (PFL) 21, 22 of coaxial cylindrical structure via a thyristor 7 and an inductor 8. The outside conductor of the PFL 21 is connected directly to ground. A saturable reactor 24 is connected between the output terminal 21b of the center conductor of the PFL 21 and the output terminal 22c of the outer conductor of the PFL 22. A saturable reactor 25 is connected between the output terminal 22b of the center conductor of the PFL 22 and the load terminal 4a of the load 4. Both the saturable reactors 24, 25 are simultaneously applied and the PFL 21, 22 charged in parallel are connected in series among the output terminals 21b, 22c, 22b and connected to the load 4.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse generator for supplying high voltage square wave pulses to an electron gun, klystron, etc., and more particularly to a pulse generator capable of efficiently supplying high voltage pulses to a high impedance load.

0002

2. Description of the Related Art Conventionally, as a circuit for generating pulses, a square wave pulse generating device combining a capacitance element, an inductance element, and a thyratron has been frequently used.

FIG. 5 shows a conventional square wave pulse generator of this type. In this square wave pulse generator, a pulse forming line (PFL) 1 is charged to a constant voltage by a charging circuit 2. By turning on the thyratron 3 in this state, a square wave pulse can be generated in the load 4.

The withstand voltage of the thyratron 3 is normally several tens of kilovolts, and if a voltage higher than that is to be generated, a pulse transformer 5 is used to boost the voltage as shown in FIG. PFL1
When using, the impedance of the line needs to be equal to the impedance of the load, and the output voltage becomes 1/2 of the charging voltage on the primary side of the pulse transformer 5.

[0005]

In the conventional square wave pulse generator, in order to increase the efficiency of particle acceleration using a high frequency amplifier tube such as a klystron, it is necessary to increase the pulse voltage and shorten the rise time.

However, when the pulse transformer 5 is used to increase the output voltage, the following problems arise. In other words, when applying a fast-rising pulse to a high-impedance load such as the klystron 3, the impedance of the stray capacitance of the pulse transformer 5 cannot be ignored with respect to the impedance of the load, and the pulse applied to the primary side of the pulse transformer 5 becomes It becomes extremely difficult to generate the waveform as it is on the secondary side.

The present invention has been made in consideration of the above-mentioned circumstances, and provides a pulse generator capable of efficiently supplying a high voltage, fast rise, and long pulse width square wave pulse to a high impedance load. The purpose is to [Structure of the invention]

[0008]

[Means for Solving the Problems] As a means for achieving the above object, the present invention includes a pulse shaping section, a charging circuit for the pulse shaping section, and a closing switch connected between the pulse shaping section and a load, In the pulse generator that generates a square wave pulse at a load terminal by charging the pulse shaping section to a predetermined voltage and then closing the closing switch, a plurality of pulse shaping sections are connected to the charging circuit at an input side terminal. They are connected in parallel and also connected in series via a second closing switch at the output terminal.

[0009]

[Operation] In the pulse generator according to the present invention, when the closing switch and the second closing switch are turned on at the same time, the plurality of pulse forming sections charged in parallel are connected in series at the output side terminal. It will be connected to the load. Therefore, if the number of pulse shaping sections is N, a square wave pulse having a peak value N/2 times the charging voltage is supplied to the load.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a pulse generator according to the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows an example of a pulse generator according to the present invention. In the figure, reference numeral 2 is a charging circuit, a capacitor 6 is connected to the charging circuit 2, and a high voltage terminal of the capacitor 6 is connected to the charging circuit 2. is the thyristor 7 and the inductance 8
A pulse forming line (PFL) with two coaxial cylindrical structures is connected via
) 21, 22 are connected to the input side terminals 21a, 22a of the center conductors.

The outer conductor of the PFL 21 is directly grounded as shown in FIG. 1, and the outer conductor of the PFL 22 is grounded via a resistor 9. Also, PFL21
A saturable reactor 24 serving as a magnetic switch is connected between the output terminal 21b of the center conductor of the PFL 22 and the output terminal 22c of the outer conductor of the PFL 22.
A saturable reactor 25 serving as a magnetic switch is connected between the output side terminal 22b of the center conductor 22 and the load terminal 4a of the load 4.

Both saturable reactors 24 and 25 are
As shown in FIG. 2, two coils 26 and 27 are wound in parallel around the same magnetic core 11. Therefore, both saturable reactors 24 and 25 are simultaneously activated by the saturation of the core 11. It is now in the input state. Note that the surge impedance of both the PFLs 21 and 22 is set to have a value that is 1/2 of the impedance of the load 4. Next, the operation of this embodiment will be explained.

When the thyristor 7 is turned on, the charge charged in the capacitor 6 by the charging circuit 2 is converted into a pulse having a rise time determined by the capacitance of the capacitor 6 and the inductance 8, and is applied to the input of the center conductors of the two PFLs 21 and 22. It joins the side terminals 21a and 22a, and PFL2
1 and 22 are charged in parallel to a predetermined charging voltage Vo.

However, when the rise time of the pulse that charges the PFL 21 is τ, and the capacitance between the center conductor and the outer conductor of the PFL 21 is c, the value r of the resistor 9 is
should be small enough to satisfy the following equation. Cr<<τ

[
[0016] The entire PFLs 21 and 22 are at a predetermined voltage Vo.
When the battery is charged to the maximum, a voltage Vo is applied between the poles of the saturable reactors 24 and 25. Here, the saturable reactor 24
, 25 and the number of turns of the coils 26, 27 is set equal to the voltage-time product determined by the charging pulse rise time τ and the charging voltage Vo. When charged to Vo,
The inductance of the saturable reactors 24 and 25 rapidly decreases from the unsaturated value to the saturated value when the core 11 is saturated. That is, the saturable reactor 24,
25 has the same effect as if the switches were turned on at exactly the same time between the output side terminals 21b and 22c and between the output side terminal 22b and the load terminal 4a due to the sudden decrease in impedance.

Then, the output terminals 21 of the PFLs 21 and 22
b, 22b, and 22c are connected to the load 4 in series. Therefore, when there is only one PFL, only a square wave pulse having a peak value of 1/2 of the charging voltage Vo can be supplied to the load 4, whereas when there are two PFLs 21,
22, it is possible to supply the load 4 with a square wave pulse having twice the peak value of Vo.

The rise time Tf of the square wave pulse is determined by the residual inductance of the saturable reactors 24 and 25 as Ls
, where R is the impedance of the load 4, it is given by the following equation, and can be shortened by reducing the residual inductance Ls. Tf=Ls/R

The value r of the resistance 9 of the outer conductor of the PFL 22 is
If the following relationship is satisfied for the output pulse width T, the outer conductor of the PFL 22 will not be grounded and the potential of the output terminal 21b of the PFL 21 will be applied to the output pulse. Cr>>T

FIGS. 3(A), (B), (C) and (D)
In the circuit of this embodiment, each terminal 21b, 22c, 2
The voltage waveforms of 2b and 4a are shown. In FIG. 3, the thyristor 7 is turned on at t=0, and the saturable reactor 24 is turned on at t=To.
25 is saturated, and the output side terminal 22c has a square wave with a peak value of 1/2 of the charging voltage Vo.
Further, a square wave pulse having a peak value Vo twice that of the square wave pulse is applied to the load terminal 4a. In addition, the pulse width at this time is
It is equal to the round trip propagation time of PFL21,22.

Therefore, the saturation voltage of the saturable reactors 24 and 25 is determined by the cross-sectional area of the magnetic core 11 and the coils 26 and 2.
Since it can be arbitrarily determined depending on the number of turns of PFL1
There are no restrictions on the switching operating voltage per stage.

Furthermore, since two stages of PFLs 21 and 22 are used, a square wave pulse having a peak value equal to the charging voltage on the input side can be obtained. Then, by stacking N stages of PFL and connecting them to the coil of a saturable reactor wound in N parallel, a square wave pulse with a peak value of NVo /2 can be obtained with respect to the charging voltage Vo, and the number of stages of PFL is By increasing the voltage, a higher voltage can be easily achieved. Therefore, there is no need to step up the voltage with a pulse transformer, and a distortion-free high voltage square wave pulse can be obtained.

[0023] Also, two saturable reactors 24, 25
are wound around the same magnetic core 11, so there is no timing difference in the switching action due to the saturation of the magnetic core 11, and the switches are turned on at exactly the same time, ensuring that the rise of the output pulse is sufficiently controlled. It can be made shorter. Figure 4
This shows a second embodiment of the present invention, in which PFLs 31 and 32 are used in place of the PFLs 21 and 22 in the first embodiment.

That is, as shown in FIG. 4, the PFLs 31 and 32 have a double cylindrical structure similar to the PFLs 21 and 22 in the first embodiment, but the inner conductor 33 of the line
is formed by winding a conductor in a spiral shape on an insulating cylinder 34. Regarding other points, please refer to the above-mentioned Part 1.
It has the same configuration as the embodiment, and the operation is also the same. By using PFLs 31 and 32, the capacitance C per unit length of the line remains the same, but the inductance L increases, the line surge impedance Z shown by the following equation increases, and the propagation velocity V decreases. Become. Therefore, it is suitable when the load impedance is high.
Another advantage is that a desired pulse width can be obtained even with a short line length.

[0025] In both of the above embodiments, PFL21, 2
Although the case where lines 2, 31, and 32 have a double cylindrical structure has been described, lines having other structures may be used, such as lines having a parallel plate conductor structure.

The pulse shaping section also includes a pulse shaping line (
In addition to PFL), for example, a so-called pulse shaping circuit (PFN) in which lumped inductance and capacitance are configured into a ladder-shaped circuit may be used. Since this PFN can easily obtain a large inductance, it is suitable for obtaining a square wave pulse with a long pulse width.

[0027]

[Effects of the Invention] As explained above, the present invention connects a plurality of pulse shaping units in parallel to the charging circuit at the input side terminals, and connects them in series at the output side terminals via the second closing switch. This makes it possible to efficiently supply a high voltage, fast rising square wave pulse with a long pulse width to a high impedance load.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a pulse generator according to a first embodiment of the present invention.

FIG. 2 is a detailed view of the magnetic switch portion of FIG. 1;

3A, 3B, 3C, and 3D are voltage waveform diagrams at each terminal in the circuit of FIG. 1;

FIG. 4 is a configuration diagram of a PFL according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional pulse generator.

[Explanation of symbols]

2 Charging circuit 4 Load 4a Load terminals 21, 22, 31, 32 Pulse forming line (PFL)
21a, 22a Input side terminals 21b, 22b, 22c Output side terminals 24, 25
Saturable reactor 26, 27 coil

Claims (1)

[Claims] 1. A pulse shaping section, a charging circuit for the pulse shaping section, and a closing switch connected between the pulse shaping section and a load, wherein the closing switch is turned on after charging the pulse shaping section to a predetermined voltage. In the pulse generator that generates square wave pulses at the load terminal by closing, the plurality of pulse shaping units are connected in parallel to the charging circuit at the input side terminal, and a second closing switch is connected at the output side terminal. A pulse generator characterized in that the pulse generator is connected in series through the pulse generator.