JP2576303B2 - Radiation generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation generator for accelerating a charged particle beam, deflecting the beam by an electromagnetic field, and radiating the beam to a target.

[0002]

2. Description of the Related Art FIG. 8 is a front view of a radiation generator in which a 270 ° bending electromagnet is added to a conventional electron accelerator, and FIG. 9 is a plan view thereof. In the figure, 1 is an electron gun, 2 is an electron accelerator provided on the output side of the electron gun 1, 3 is a vacuum duct provided on the output side of the electron accelerator 2, 4 is a vacuum duct 3
The first pole tip 5 of the 270 ° bending electromagnet which forms a bending electromagnetic field therein is the second pole tip 5 of the 270 ° bending electromagnet.

Next, the operation will be described. The electrons emitted from the electron gun 1 are accelerated by the accelerator 2 to become a high energy electron beam, and enter the vacuum duct 3. The incident high-energy electron beam is deflected by 135 ° in the electromagnetic field generated in the vacuum duct 3 by the first pole 4 of the 270 ° bending electromagnet, and further deflected by 135 ° in the electromagnetic field generated by the second pole 5 to form the vacuum duct. From 3, a high energy electron beam is emitted to the target.

[0004]

Since the conventional radiation generator is configured as described above, the trajectory of the electron beam passing through the vacuum duct is unknown, and the average energy of the electrons and the spread of the energy can be recognized. And control was not possible. The present invention has been made to solve the above problems, and has as its object to provide a radiation generator capable of monitoring and controlling the energy of electrons.

[0005]

According to the present invention, there is provided a radiation generating apparatus for radiating a charged particle beam accelerated by a charged particle accelerator by deflecting the beam by an electromagnetic field in a vacuum duct, wherein the charged particle beam has a high energy beam and a low energy beam. A pair of beam collectors provided at positions in the vacuum duct that are dispersed to the maximum with the energy beam, and a monitoring device that monitors a high energy beam amount and a low energy beam amount from the pair of beam collectors are provided. It was done.

[0006]

According to the present invention, as shown in FIG. 10, a charged particle beam having a spread of energy is deflected in an electromagnetic field, a charged particle having a high energy is on the outer side X, and a charged particle having a lower energy is on the inner side. Pass through Y. Due to this energy difference, a high energy beam amount and a low energy beam amount are detected by a pair of collectors installed at positions where the trajectories of the charged particles are maximally dispersed. Further, the energy of the charged particle beam is controlled based on the detected beam amount.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a front view showing an embodiment of the radiation generating apparatus according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and the same parts as those in FIG. I do. In the figure, 6 is a high energy beam collector mounted in the vacuum duct 3, 7 is a high energy beam collector signal connector, 8 is a low energy beam collector mounted in the vacuum duct 3, 9 is a low energy beam This is a collector signal connector, and the beam collectors 6 and 8 are provided corresponding to the maximum dispersion position of the trajectory of the charged particle beam shown in FIG. Reference numeral 10 denotes an insulating plate for electrically insulating the vacuum duct 3 from the beam collectors 6 and 8;
Reference numerals 1 and 12 are conductors connecting the beam collectors 6 and 8 and the connectors 7 and 9. .Phi. Indicates a position with respect to the beam collector 8, and .phi.0 indicates a center position between the collectors 6, 8. FIG.

FIG. 3 shows a microwave output control circuit when two energy collector signals detected by the beam collectors 6 and 8 are used for beam energy control.
21 is a preamplifier for amplifying a collector signal, 22 is a sample and hold circuit for sampling and holding a pulse signal from the preamplifier 21, 23 is a differential amplifier for producing a difference signal between a high energy signal and a low energy signal, and 24 is integrating the difference signal. 25 is a variable resistor that presets the microwave output, and 26 is an amplifier that outputs the difference between the output of the integration circuit 24 and the output of the variable resistor 25.

Next, the operation of the above embodiment will be described. The electron beam accelerated by the accelerator 2 is 270 ° by a magnetic field perpendicular to the vacuum duct 3 generated by the 270 ° bending magnet device.
゜ It is deflected. As shown in FIG. 10, if the accelerated electron beam has a certain energy dispersion, the position dispersion becomes maximum when the electron beam is deflected by 135 °. Since the collector 8 is arranged on the low energy beam side and the collector 6 is arranged on the high energy side, each collector catches the low energy end beam current and the high energy end beam current.

FIG. 4 is a characteristic diagram showing the relationship between the beam orbital position φ and the beam current density I (φ), where B is a beam having a predetermined energy, A is a beam having a lower energy than B, and C is a beam having a lower energy than B. B represents the current density of each beam having a higher energy than B. When the energy of the electron beam decreases, the beam orbital position φ decreases, the amount of current captured by the low energy collector 8 increases, and the high energy collector 6, the amount of current to be captured decreases. Conversely, when the energy of the electron beam increases, the current amount of the low energy collector 8 decreases, and the high energy collector 6
Current amount increases. φ1 and φ2 indicate the position of the low energy collector 8 and the position of the high energy collector 6, respectively.

The high energy collector signal and the low energy collector signal respectively captured by the pair of collectors 6 and 8 are amplified by the preamplifier 21 shown in FIG. The held signal is taken out of the difference signal by the differential amplifier 23 and held by the integration circuit 24. The differential amplifier 26 outputs the difference signal between the held signal and the output of the variable resistor 25. The output of the differential amplifier 26 is used as a microwave output adjustment signal to be input to the accelerator 2, for example, a control signal of a high-voltage power supply output. That is, as shown in FIG.
The output of the microwave can be automatically controlled by adjusting the polarity so that the microwave becomes smaller as the high energy collector signal becomes larger and vice versa.

In the above embodiment, the case where both collector signals are input to the microwave output control circuit shown in FIG. 3 has been described. However, by inputting them to the deflection magnet current optimum value monitor circuit shown in FIG. It can be used for current adjustment signals. That is, the signal obtained by adding the low-energy collector signal and the high-energy collector signal by the adding circuit 27 has a maximum value when the track is in a predetermined orbit, as shown in FIG. Therefore, it is possible to adjust the density per hour (coil current) of the bending electromagnet to an optimum value while monitoring the added value. Further, automatic control may be performed.

[0013]

As described above, according to the present invention, since the collector for the low energy beam and the collector for the high energy beam are arranged in the charged particle deflection system, the trajectory of the charged particle beam can be monitored, and based on each collector signal. By automatically adjusting the microwave output, the beam energy can be stabilized. Further, by adjusting the electromagnetic field intensity of the deflection system based on each collector signal, there is an effect that the beam can be set to a correct trajectory.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of a radiation generator according to the present invention.

FIG. 2 is a sectional view taken along line AA of the radiation generating apparatus of FIG.

FIG. 3 is a microwave output control circuit used in the radiation generator of FIG. 1;

FIG. 4 is a diagram showing a beam orbit position-beam current density characteristic.

FIG. 5 is a graph showing a relationship between a microwave output and a collector current.

FIG. 6 is a deflection electromagnet current optimum value monitoring circuit used in the radiation generator of FIG. 1;

FIG. 7 is a graph showing a relationship between a speed density of a bending electromagnet and an added value of high and low collector currents.

FIG. 8 is a front view of a conventional radiation generator.

FIG. 9 is a plan view of a conventional radiation generator.

FIG. 10 is a diagram illustrating the trajectory of electrons in the radiation generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Accelerator 3 Vacuum duct 4 First pole tip of bending electromagnet 5 Second pole tip of bending electromagnet 6 Collector for high energy beam 8 Collector for low energy beam

Claims (3)

(57) [Claims] 1. A radiation generator for radiating a charged particle beam accelerated by a charged particle accelerator by deflecting the beam by an electromagnetic field in a vacuum duct, wherein the charged particle beam is maximally dispersed into a high energy beam and a low energy beam. A radiation generator comprising: a pair of beam collectors provided at positions in a vacuum duct; and a monitor device for monitoring a high energy beam amount and a low energy beam amount from the pair of beam collectors. 2. The monitoring device according to claim 1, further comprising means for detecting a difference between a high energy beam amount and a low energy beam amount, and controlling a microwave output of the charged particle accelerator based on a value of the detected difference. Claim 1 characterized by the following:
A radiation generator according to any of the preceding claims. 3. The monitoring device according to claim 1, further comprising means for adding a high energy beam amount and a low energy beam amount, and controlling the intensity of the deflected electromagnetic field of the charged particle beam based on the added value. The radiation generator according to claim 1.