JPH03185912A - Pulse generator - Google Patents

Abstract

PURPOSE:To generate a rectangular wave with a wide pulse width even when a guide length in matching with a high impedance load is not prolonged by arranging a multiple spiral line inside of a cylindrical conductor as a bloom line. CONSTITUTION:An intermediate conductor 12 charged by a charge power supply 17 connects to ground by closing a switch 18. As a result, a step wave having the rise depending on the characteristic of the switch 18 propagates through a distributed constant line comprising center conductors 11, 12. When the step wave reaches the output terminal of the bloom line (comprising spiral conductors 11, 12 and a cylinder 13), a step voltage is applied to a load 15. The step wave is branched at the output terminal, propagates again at the input terminal, returns, is reflected again and reaches the output terminal, then the rising voltage applied to the load 15 is 0V. As a result, a rectangular wave having a pulse width equivalent to the reciprocating time along the spiral path of the spiral center conductor and of the intermediate conductor 12 is applied to the load 15.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a pulse generator that supplies high voltage rectangular wave pulses to electron guns, klystrons, etc.
In particular, it relates to techniques for improving its operating characteristics.

(Prior art) In the past, thyratrons were often used as switching elements in circuits that generate pulses because of their large allowable current increase rate and relatively high withstand voltage; Figure 2 shows This is an example of a rectangular wave pulse generator using a thyratron. In this device, a rectangular wave pulse can be generated in the load 5 by charging the pulse forming line 2 to a constant voltage by the charging power supply 1 and then turning on the thyratron 3. In this case, the withstand voltage of the thyratron 3 is usually several tens of kV, and if a higher voltage is to be generated, a pulse transformer 4 is used to boost the voltage as shown in the figure. When the pulse forming line 2 is used, the impedance of the line must be equal to the impedance of the load, and the output voltage will be 1/2 of the charging voltage on the primary side of the pulse transformer.

In addition to using a pulse transformer, there is a method of serializing pulse forming lines such as Blumlein type and stack line type to increase the output voltage.

Figure 3 shows a rectangular wave pulse generator using Blumlein 6, and the switching element is Illatron 3.
is used. When using the Blumlein 6, the impedance between the first conductor 61 and the second conductor 62 is 2.
1. If the impedance between the second conductor 62 and the third conductor 63 is 22, and the impedance of the load 5 is R, then if R/2 = Z1 = Z2, the output will be equal to the charging voltage. A square wave pulse of voltage is obtained.

[Problems to be Solved by the Invention] Incidentally, in order to increase the efficiency of particle acceleration by a high-frequency amplifier tube such as a klystron, it is necessary to increase the pulse voltage and shorten the pulse voltage.

If it is desired to further increase the output voltage, there is a limit to simply connecting the pulse forming lines in series, and if a thyratron is used as a switching element, a pulse transformer will eventually have to be used. However, the method using a pulse transformer has the following problems.

In other words, when applying a fast pulse to a high impedance load such as a Talistron, the impedance of the stray capacitance of the pulse transformer cannot be ignored relative to the impedance of the load, and the waveform applied to the primary side of the transformer changes. It becomes extremely difficult to generate this directly on the secondary side.

Furthermore, when attempting to use such a pulse generator at high repetition rates, the short lifespan of the thyratron becomes a problem. That is, a thyratron generally has a lifespan of about 108 shots, but when operated at a high repetition rate of, for example, 1000 pps, it must be replaced after about 30 hours, making it virtually impossible to operate the entire device continuously for a long time.

On the other hand, when a Blumlein type pulse forming line is used to increase the voltage of the pulse and shorten the rise time without using a pulse transformer, the following problems arise.

That is, in the conventional Blumlein type pulse forming line, the pulse width is determined by the round trip propagation time of the line, so in order to obtain a pulse with a wide pulse width of several hundred ns, for example, a Blumlein line with a length of several tens of meters is necessary. A line will be required.

Furthermore, in order to match the impedance of the Blumlein line with a high impedance load such as a klystron, the width of the hollow portion of the Blumlein line must be made very large.

For these reasons, in order to supply a wide pulse voltage to a high load impedance, a gigantic Blumlein line is required, making installation extremely difficult in practice.

The present invention has been made in view of the above points, and it is possible to generate a rectangular wave pulse with a high voltage, a fast rise, and a long pulse width.
It is an object of the present invention to provide a compact pulse generator that can efficiently supply a high impedance load.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the pulse generator of the present invention is a rectangular wave pulse generator that combines a Blumlein and a switching element. Its structural feature is that multiple spiral lines are arranged inside a cylindrical conductor.

(Function) In the present invention having the above configuration, by making the conductor forming the Blumlein into a spiral shape,
The inductance per unit length in the axial direction of the cylindrical conductor of the line increases, and the surge impedance seen from the output end increases even without a large hollow part. Furthermore, since the total line length along the spiral can be increased without increasing the length of the cylindrical conductor, the pulse width determined by the round trip time of the total line length can be increased.

(Example) An example of the present invention will be specifically described below with reference to FIG.

*Configuration of Example In the example shown in FIG. 1, the spiral center conductor 11
An intermediate conductor 12, which is similarly arranged in a spiral manner around the outer periphery, is arranged concentrically inside the cylindrical conductor 13, and a bloom line is formed by each of these conductors.

Here, the cylindrical conductor 13 corresponds to the first conductor 61 shown in FIG. 3, the intermediate conductor 12 corresponds to the second conductor 62, and the center conductor 11 corresponds to the third conductor 63. That is, on the input end side of the Blumlein, the spiral intermediate conductor 12 is connected to the charging power source 17 via the resistor 16, and the central conductor 1
1 and the intermediate conductor 12 is provided with a short-circuit switch 1.8. Further, on the output end side of the Blumlein, a load 15 to supply a rectangular wave pulse is provided between the center conductor 11 and the cylindrical conductor 13.

In this case, a spiral central conductor 11 and an intermediate conductor 12
The turns are insulated by an insulator 14. The winding radius rl of the central conductor 11, the winding radius r2 of the intermediate conductor 12
, and the radius r3 of the cylindrical conductor 13 are the surge impedance of the parallel plate distributed constant line consisting of the center conductor 11 and the intermediate conductor 12, and the surge impedance of the parallel plate distributed constant line formed from the intermediate conductor 12 and the cylindrical conductor 13. has a matching value. Moreover, the spiral conductor 11.
The number of turns per unit length in the axial direction of the 12 cylindrical conductors 13 is as follows: The axial unit length surge impedance of the conductor 13 is adjusted to be 1/2 of the impedance of the load 15 connected to this Blumlein.

Furthermore, the length D of the cylindrical conductor 13 is such that the time for the electric pulse to reciprocate along the entire length of the spiral central conductor 11 and intermediate conductor 12 becomes the pulse width of the rectangular wave pulse applied to the load 15. It has been adjusted as follows.

Functions of this embodiment The functions of this embodiment having the above-described configuration are as follows.

First, the intermediate conductor 12 charged by the charging power source 17 is grounded by closing the switch 18.

Then, a step wave having a rising edge determined by the characteristics of the switch 18 propagates through the distributed constant line composed of the center conductor 11 and the intermediate conductor 12.

When this step wave reaches the output end of the Blumlein,
A step voltage is applied to the load 15.

When this step wave is split at the output end, propagates again to the input end, and is reflected once again and reaches the output end, the voltage applied to the load 15 becomes OV. Become. As a result, the load 15 has a spiral center conductor 11
A rectangular wave having a pulse width corresponding to the round trip time along the spiral of the intermediate conductor 12 is applied.

At this time, when looking at the impedance of the Blumlein line housed in the cylindrical conductor 13 from the output end,
In order to match the load 15, the surge impedance per unit length in the axial direction of the cylindrical conductor of the propagation line consisting of the center conductor 11 and the intermediate conductor 12 and the propagation line consisting of the intermediate conductor 12 and the cylindrical conductor 13 must be equal to the load 15, respectively. 1/
2, it is possible to achieve this by changing the inductance of the line by adjusting the number of turns per unit length of the spiral as described above.

As described below, according to this embodiment, the following effects can be obtained.

- Since the Blumlein line is constructed using a spiral conductor, when generating a rectangular wave with a wide pulse width, a significantly shorter Blumlein line is required compared to conventional means.

■Since the surge impedance of the Blumlein line can be adjusted by the number of turns of the spiral, it is possible to adjust the surge impedance of the high impedance line with a significantly smaller shape compared to conventional means.
It can be matched with loads.

(Other Examples) Although the above embodiment has a structure in which a double concentric spiral conductor is housed inside a cylindrical conductor, the present invention is not limited to the above embodiment. It is also possible to have a multiplex configuration.

Further, the spiral structure is not limited to a cylinder, but may be a rectangular cylinder, an ellipse, or any other shape as long as it constitutes a distributed constant line.

Moreover, even if there is no insulating distance in the plane, the spiral may be wound in layers with an insulating material interposed therebetween.

[Effects of the Invention] As described above, according to the present invention, the central conductor and the intermediate conductor housed inside the cylindrical Blumlein conductor are constructed from spiral conductors, which is extremely simple.
It is possible to obtain a pulse generator capable of generating a rectangular wave with a wide pulse width that matches a high impedance load without increasing the length of the cylindrical conductor.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view showing an embodiment of the pulse generator of the present invention, Fig. 2 is a circuit diagram showing an example of a conventional pulse generator, and Fig. 3 is a rectangular waveform using a conventional Blumlein. FIG. 2 is a circuit diagram showing a pulse generator circuit. 1... Charging power supply, 2... Pulse forming line, 3...
Thyratron, 4... Pulse transformer, 5... Load, 6... Blumlein, 61... First conductor, 6
2...Second conductor, 63...Third conductor, 11...
- Center conductor, 12... Intermediate conductor, 13... Cylindrical conductor, 14... Insulator, 15... Load, 16... Resistor, 17... Charging power source, 181... Switching element. 2

Claims (1)

[Claims] (1) In a pulse generator that includes a Blumlein connected to a power source and a switching element and generates a rectangular wave pulse to a load connected to the Blumlein, the Blumlein is a multi-spiral winding inside a cylindrical conductor. A pulse generator characterized by using a track on which lines are arranged.