JPH03185914A - Pulse generator - Google Patents

Abstract

PURPOSE:To obtain a steep rising high voltage rectangular wave pulse with less fluctuations of a peak by providing a dielectric substance inserted and arranged between conductors forming a distributed constant line to the end of the distributed constant line to move in the lengthwise direction of the conductors. CONSTITUTION:When a load 10 connecting to a distributed constant line is fluctuated, drivers 25a, 25b and torque converters 24a, 24b move dielectric substances 23a, 23b horizontally to change the rate of the inserted dielectric substance into the distributed constant line in the lengthwise direction. As a result, the static capacitance between a center conductor 9 and an intermediate conductor 8 and between the conductor 8 and a ground metallic waveguide 20 thereby compensating a change in a pulse voltage due to the fluctuation of the load. The rate of the insertion of the dielectric substances 23a, 23b to the distributed constant line is changed and the static capacitance among the conductor 9, 8, 20 is changed. As a result, the steep rising high voltage rectangular wave pulse can constantly be generated.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention is used as a power source for particle accelerators, high-frequency pulse generators, etc., and has a high-speed rise and small fluctuation in wavefront value. The present invention relates to a pulse generator capable of generating rectangular wave pulses.

(Prior Art) Conventionally, as a method for generating rectangular wave pulses, a pulse shaping circuit (PFN) in which a coil and a capacitor are connected in a ladder shape as shown in FIG. 3 has been mainly used. Also,
In recent years, in particle acceleration power sources and high-frequency particle accelerators used in free electron lasers, in order to obtain high-quality particle beams, it has been required that the fluctuation in the peak value be approximately 1%, and the There is a growing demand for quality. However, in the pulse shaping circuit shown in Fig. 3, the peak value is affected by temporal fluctuations in the value of the load 6, high voltage pulse transformer 4, other characteristics, and stray capacitance and stray inductance of the high voltage section. To reduce fluctuations,
It's not always easy.

Therefore, in such a pulse shaping circuit, as shown in Figure 3, by making coil 1 variable, the value of the coil's inductance can be finely adjusted, reducing fluctuations in the peak value, and achieving high quality. Attempts have been made to obtain a square wave.

However, recently, the accelerating voltage of a particle beam has become higher and higher, and accordingly, the voltage of the pulse power source has also increased, and a large voltage (for example, 500 kV or more) has come to be applied to the accelerating section. Therefore, it is necessary to increase the voltage in the pulse shaping section of the pulse generator as well. Further, in such a situation, it is also necessary to prevent dielectric breakdown of the pulse shaping section.

In the pulse shaping circuit shown in FIG. 3, as mentioned above, it is necessary to constantly adjust the coil 1- in order to finely adjust the pulse waveform, so an air insulation method is generally adopted. However, this air insulation method can only be applied up to about 200 kV, so there is a limit to how high the voltage can be raised.

Therefore, instead of the pulse shaping circuit as described in 2 above, a distributed constant line is being used which is capable of increasing the voltage and can generate a rectangular wave pulse with a steep pulse waveform and little fluctuation in peak value. Became.

This distributed constant line is constructed as shown in FIG. That is, a center conductor 9 and an intermediate conductor 8 are disposed coaxially within a grounded metal container 7 to form a distributed constant line. At one end of this line, a pulse transformer 3 and a switch 5 for supplying high voltage pulses are arranged, and at the other end a load 10 is connected to the center conductor 9, and at the other end, a load 10 is connected to the center conductor 9. Capacitor lia connects center conductor 9 and intermediate conductor 8
Further, a capacitor 11-b is disposed between the intermediate conductor 8 and the grounded metal container 7. Furthermore, insulating oil 12 is filled around these to improve dielectric strength. This type of distributed constant line has an insulation strength that is 5 to 10 times higher than that of the air insulation method mentioned above, so
High voltage becomes possible.

(Problems to be Solved by the Invention) However, the above-mentioned distributed constant line has the following problems to be solved. That is, a capacitor 11a is provided for pulse waveform adjustment.

11b is provided to cope with the fact that the value of the load 10 changes over time or that the value of the load differs due to its installation state. In other words, if the load value changes over time, the applied pulse voltage waveform will also differ each time, but in response to such load changes,
Capacitor 11a.

By immediately changing the capacitance of 11b, the pulse voltage can be maintained constant.

However, since the capacitors lla and llb are installed in a sealed metal container 7, each time it becomes necessary to make fine adjustments, the metal container 7 must be disassembled and the metal container 7 can be reassembled after the adjustment is completed. It is necessary to assemble the container and fill it with insulating oil, etc. Further, the capacitors lla and llb are required to have a sub-voltage of 100 to 200 T)f and 500 kV or more, but in order to make this possible, it is conceivable to configure the capacitors with ceramic capacitors.

However, when a ceramic capacitor is used to construct a capacitor with a desired insulation level, the capacitor becomes large and expensive.

The present invention has been made to solve the above-mentioned problems, and its purpose is to generate a high-voltage rectangular wave pulse that has an extremely steep rise and a small fluctuation in peak value. The object of the present invention is to provide a pulse generator capable of generating pulses.

[Structure of the Invention] (Means for Solving the Problems) The present invention comprises disposing a conductor coaxially within a grounded metal container, and filling the container with an insulating medium to form a distributed constant line. In a pulse generator in which a switch element is connected to one end of a distributed constant line, a dielectric is provided at an end of the distributed constant line to be inserted between conductors forming the distributed constant line, and this dielectric is disposed at an end of the distributed constant line. The conductor is characterized by being movable in the longitudinal direction of the conductor.

(Function) The pulse generator of the present invention having the following configuration uses a dielectric material movably inserted between conductors forming a distributed constant line as a capacitor for adjusting the pulse voltage waveform, and adjusts the pulse voltage waveform to adjust the pulse voltage waveform. Correspondingly, the dielectric is moved in the longitudinal direction of the conductor,
By adjusting the insertion ratio of the dielectric material into the distributed constant line, the capacitance between each conductor can be changed.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIGS. 1 and 2. It should be noted that the same parts as those of the conventional type shown in FIG. 4 are designated by the same reference numerals, and their explanation will be omitted.

In this embodiment, as shown in FIGS. 1 and 2,
A center conductor 9 and an intermediate conductor 8 are disposed coaxially within a grounded metal conduit 20, and a load 10 is connected to one end of the center conductor 9. This load 10 is installed in a metal tank 21,
The grounded metal conduit 20 and the metal tank 21 are connected by a flange portion 22. In addition, the ground metal conduit 20
The metal tank 21 is filled with insulating oil 12.

In addition, the center conductor 8 and the intermediate conductor 8 constituting the distributed constant line
and between the intermediate conductor 8 and the ground metal conduit 20,
Dielectrics 23a and 23b are provided, respectively, and are used as capacitors. In this embodiment, the dielectric material is disposed over half the circumference of the center conductor 9 or the intermediate conductor 8, as shown in FIG. The dielectrics 23a and 23b also include an intermediate conductor 8 and a ground metal conduit 2.
A plurality of grooves 26 are formed on the joint surface with 0, and furthermore, shaft coupling screw portions 27a and 27b are provided on one surface of both dielectrics. Further, the dielectric 23a.

23b is a driving device 25a, 25bC provided outside the ground metal conduit 20 via a driving force converter 24a, 24b connected to the shaft coupling screw portions 27a, 27b;
It is connected. And these drive devices 25a, 25b
The structure is such that the insertion ratio of dielectric material in the longitudinal direction of the distributed constant line can be changed by operating the distribution constant line.

Note that the driving force conversion devices 24a and 24b are connected to the driving device 25.
The driving force of a and 25b is converted into the direction of inserting the dielectric into the distributed constant line.

The pulse generator configured in this manner operates as described below. That is, when the load connected to the distributed constant line fluctuates, the dielectric 23 is
a and 23b are moved in the horizontal direction in the figure to change the insertion ratio of the dielectric material in the longitudinal direction of the distributed constant line. As a result, it is possible to change the capacitance between the center conductor 9 and the intermediate conductor 8 and between the intermediate conductor 8 and the ground metal conduit 20, thereby compensating for changes in pulse voltage due to load fluctuations. I can do it. Note that the rate of change in capacitance varies depending on the dielectric constant of the dielectric and the insertion rate into the distributed constant line. Further, the operation for changing the insertion ratio of the dielectrics 23a and 23b into the distributed constant line is performed by a drive device 25a provided outside the grounded metal conduit 20.

25b, there is no need to disassemble the ground metal conduit 20, making it very easy.

In this way, according to this embodiment, the capacitance between each conductor is changed by changing the insertion ratio of the dielectric material into the distributed constant line using the driving device installed outside the grounded metal conduit. , can always generate steep, high-voltage square wave pulses. As a result, it becomes possible to maintain the pulse voltage constant. Furthermore, since a dielectric material is used as a means for changing the capacitance between each conductor, costs can be significantly reduced compared to the case where expensive ceramic capacitors are used.

Note that the present invention is not limited to the embodiments described above, and the dielectrics disposed between each conductor may be disposed all around the respective conductors. Further, the type of dielectric material is not particularly limited. Furthermore, the drive device can be configured to be remotely operated or automatically operated. Furthermore, the distributed constant line does not have to have a triple coaxial structure as shown in Figure 1.
The number of coaxial layers is not particularly limited. Furthermore, the insulating medium filled around the distributed constant line may be other than insulating oil.

[Effects of the Invention] As explained above, according to the present invention, a dielectric body is provided at the end of a distributed constant line to be inserted between the conductors forming the distributed constant line, and this dielectric body is inserted between the long flat conductors. By configuring it so that it can move in the direction, it has an extremely steep rise,
It is possible to provide a pulse generator that can generate high voltage rectangular wave pulses with little variation in peak value.

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram showing an embodiment of the pulse generator of the present invention, FIG. 2 is a view taken along the line A-A in FIG. 1, and FIG. 3 is a schematic circuit diagram showing an example of a conventional pulse shaping circuit. 4 are schematic circuit diagrams showing an example of a conventional distributed constant line. 1...Variable coil, 2...Capacitor, 3, 4...
・Pulse transformer, 5. ...Switch, 6...Load, 7...Metal container, 8...Intermediate conductor, 9...Center conductor, 10...Load, lla, llb...Capacitor, 12... Insulating oil, 20...Grounded metal conduit, 21
...Metal tank, 22...Flange part, 23a, 2
3b...dielectric, 24a. 24b... Driving force conversion device, 25a, 25b... Drive device, 26... Groove, 27a, 27b... Shaft coupling screw portion. 1

Claims (1)

[Claims] In a pulse generator, a conductor is coaxially arranged in a grounded metal container, the container is filled with an insulating medium to form a distributed constant line, and a switch element is connected to one end of this distributed constant line. A pulse generator characterized in that a dielectric is provided at an end of the distributed constant line to be inserted between conductors forming the distributed constant line, and the dielectric is configured to be movable in the longitudinal direction of the conductor. .