JPH04118844A - Grid pulser - Google Patents

Abstract

PURPOSE:To obtain an electron-gun emission current having a large number of pulse repetitions as well as to stably obtain the energy accelerated in an acceleration tube, by equipping the grid pulser with a large output high-frequency amplifier intended to amplify a CW signal and a bias voltage source causing increase in set level of the output from the large output high-frequency amplifier. CONSTITUTION:The CW signal generated from a CW signal generator 21 is converted into an optical signal by an optical driver 22 and is sent into an optical receiver 24 through an optical fiber 23. In the optical receiver 24, this optical signal is converted into an electric signal, the CW signal in the form of an electric signal being inputted into a large output high-frequency amplifier 25 and thus amplified. The CW signal thus amplified is inputted into a cathode of an electron gun 28 via a coupling condenser 26. This signal being inputted is in the form of a continuous wave whose level is uplifted by a voltage VB of a bias voltage source 27. Thus, an emission current of intermittent wave is generated in the electron gun 28. Since the cyclic period of this emission current is determined depending upon the frequency band of the amplifier 25, high repetitions are also possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a grid pulser used to generate an electron gun emission current in an electron gun of a radiation accelerator.

[Conventional technology]

FIG. 6 is a block diagram showing a conventional grid pulser. In the figure, 1 is a pulse generator, 2 is an optical driver that converts the pulses output from the pulse generator 1 into optical signals,
3 is an optical fiber that transmits this optical signal, and 4 is an optical receiver that converts the optical signal obtained from this optical fiber 3 into electrical signal pulses.

5 is a pulse amplifier that amplifies this pulse, 6 is a coupling capacitor, 7 is a bias power supply that applies a constant level voltage to the cathode of the electron gun, and 8 is the electron gun.

Next, the operation will be explained.

First, a pulse generated by a pulse generator 1 is converted into an optical signal by an optical driver 2 and sent to an optical receiver 4 through an optical fiber 3. The optical receiver 4 converts the optical signal into an electrical signal and inputs it to the pulse amplifier 5. The pulse amplifier 5 inputs the output pulse, which is an electric signal, to the cathode of the electron gun 8 via the coupling capacitor 6.

As a result, electron emission is output from the electron gun 8. In this case, the bias power supply 7 is.

While the output pulse is not coming, a voltage at a certain level is applied to the cathode so that no emission is emitted from the electron gun 8. Note that the heater circuit of the electron gun 8 is omitted in the diagram.

[Problem to be solved by the invention]

Since the conventional grid pulser is configured as described above, it is necessary to use the pulse amplifier 5 to increase the signal input to the cathode of the electron gun 8, and the pulse amplifier 5 with a high output voltage is used as a switching circuit. However, there were problems such as the inability to obtain an electron free emission current with a high pulse repetition rate.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a grid pulser that can output an electron gun emission current with a high pulse repetition rate by using a high frequency amplifier.

(Means for Solving the Problems) A grid pulser according to the present invention includes a continuous wave high output high frequency amplifier i which amplifies a continuous wave signal from a continuous wave signal generator, and an output of the four high output high frequency amplifiers. A bias power supply that raises the voltage by a set level, and generates an electron gun emission current when the output signal voltage of the high-output high-frequency amplifier obtained through the bias power supply is equal to or higher than the cutoff voltage of the electron gun. It is.

[Effect]

The grid pulser in this invention amplifies a high frequency continuous signal sent from an optical receiver using a high output high frequency amplifier for continuous waves, and this amplified high frequency continuous signal is applied to an electron gun. To obtain an electron gun emission current when the voltage is higher than the off-state voltage.

[Embodiment J of the invention An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 21 is a continuous wave (hereinafter referred to as CW) signal generator, 22 is an optical driver that converts the signal into a CW multiplied optical signal and outputs it, 23 is an optical fiber, and 24 is an optical fiber 23.
an optical receiver that converts the optical signal obtained through the
25 is a high-output high-frequency amplifier that amplifies the converted electric signal by CW, 26 is a coupling capacitor, 27 is a bias power supply that increases the output of the high-power high-frequency amplifier 25 by a set level, and 28 is obtained through the bias power supply. The electron gun generates an electron gun emission current when the output signal voltage of the high output high frequency amplifier 25 is equal to or higher than the cutoff voltage.

Next, the operation will be explained.

First, a CW multiplied signal generated by the CW signal generator 21 is converted into an optical signal by the optical driver 22 and sent to the optical receiver 24 through the optical fiber 23. This optical receiver 24 converts this optical signal into an electrical signal, and inputs the CW multiplied signal of this electrical signal into a high-output high-frequency amplifier 25 for amplification. The CW multiplied signal amplified here is further input to the cathode of the electron gun 28 via the coupling capacitor 26. The signal input to the cathode of the electron gun 28 at this time is a continuous wave whose level is raised by the voltage vIl of the bias power supply 27, as shown in FIG. 2(a). When such a CW voltage is input to the cathode of the electron gun 28, an intermittent wave emission current as shown in FIG. 2(b) is generated in the electron gun 28. That is, if the CW voltage to the cathode of the electron gun 28 is below the cutoff voltage of the electron gun 28, the emission current becomes zero, and if it is above the cutoff voltage, the emission current is half the CW voltage of the cathode. Since it flows in proportion to the third power,
Even when such a high-power high-frequency amplifier 25 is used, a pulsed emission current can be obtained as shown in FIG. 2(b). Since the cycle of this emission current, that is, the number of pulse repetitions, is determined by the frequency band of the high-output high-frequency amplifier 25, high repetition of several hundreds of MHz is also possible. Here, the CW signal generator 21 may be the same pulse generator as the conventional one.

Further, although the electron gun 28 is grounded to the grid, it may be a cathode grounded type electron gun, and in this case, the bias power supply 2
The polarity of 7 is reversed.

Note that in the above embodiment, while applying a high voltage to the cathode in order to draw out the emission current with the electron gun 28,
A pulsed emission current is obtained by the CW multiplied signal, but if the high voltage is a pulse, modulating the output signal of the optical receiver 24 with a pulse signal synchronized with the high voltage pulse will generate an arbitrary number of emission pulses. can be obtained efficiently. Figure 3 is a block diagram in this case,
29 is a pulse modulation circuit. By inputting the output signal of the optical receiver 24 and the pulse modulation signal as described above to the modulation circuit 29, a pulse modulated signal is obtained.

Figure 4 shows the signal waveforms of each part of the block in Figure 3.
4(c) shows the output waveform of the optical receiver 24, FIG. 4(d) shows the high voltage pulse, FIG. 4(e) shows the pulse modulation signal, and FIG. 4(a) shows the output waveform applied to the cathode of the electron gun 28. The signal is pulse modulated.

Further, FIG. 4(b) shows the emission current of the electron gun 28.

Also, FIG. 5 shows signal waveforms of each part of the block in FIG. 3 to explain another method of obtaining an emission pulse. According to this, the width of the pulse modulation signal in FIG.
) is wider in front of the high voltage pulse. Depending on the high-output high-frequency amplifier 25, when pulse modulated as described above, the peak value of the amplitude of the cathode signal of the electron gun 28 may oscillate at the rising edge of the modulation as shown in FIG. 5(a). If such a signal is used to extract the emission from the electron gun 28, not only will the emission current value change, but the accelerated energy will also change depending on the loading characteristics of the accelerating tube after the electron gun 28, making it undesirable as an accelerator. . Therefore, as shown in FIG. 5(e), the pulse modulation signal is spread forward, and as shown in FIG.
) After the vibration of the output signal of the high-power high-frequency amplifier 25 shown in FIG. Emission current with uniform level can be stably obtained,
The energy accelerated by the accelerator tube can be stabilized.

〔Effect of the invention〕

As described above, the present invention includes a high-output high-frequency amplifier that amplifies a CW signal from a CW signal generator, and a bias power supply that increases the output of the high-power high-frequency amplifier by a set level, and When the output signal voltage of the high-output high-frequency amplifier obtained by the above-described method is higher than the cutoff voltage of the electron gun, the electron gun emission current is generated. This has the effect of being able to obtain an emission current and stably obtaining energy for acceleration in the accelerator tube.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing a grid pulser according to an embodiment of the present invention, Fig. 2 is a timing chart showing signals of each part of the block in Fig. 1, and Fig. 3 is a block diagram showing a grid pulser according to an embodiment of the present invention. A block diagram of a grid pulser showing another embodiment, FIGS. 4 and 5 are timing charts showing signals of each part of the block when emission pulses are obtained in a different way from FIG. 3, and FIG. 6 is a conventional example. FIG. 2 is a block diagram showing a grid pulser of FIG. 21 is a continuous wave (CW) signal generator, 25 is a high output high frequency amplifier, 27 is a bias power supply, and 28 is an electron gun. In addition, in the figures, the same symbols indicate the same or equivalent parts. Agent for patent applicant Mitsubishi Electric Corporation

Claims (1)

[Claims] a high-output high-frequency amplifier for continuous waves that amplifies a continuous-wave signal from a continuous-wave signal generator; a bias power supply that increases the output of the high-power high-frequency amplifier by a set level; A grid pulser comprising an electron gun that generates an electron gun emission current when the output signal voltage of the output high frequency amplifier is equal to or higher than the cutoff voltage.