JPH0517840Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a deflector device for irradiating an ion beam in a cyclotron to a target inside the target box by passing it through a target oil at the entrance of the target box through a beam extraction passage. In particular, in a cyclotron, the extracted ion beam is scanned vertically or horizontally over the target oil at the entrance of the target box, and the ion beam that has uniformly passed over the entire surface of the target oil can be irradiated all over the target. It relates to a deflector device.

[Prior art] The conventional device is a cyclotron 1 as shown in Figure 3.
The ion beam 2 is taken out into the beam extraction passage 4 by applying a DC voltage E to the deflector 3, and this ion beam 2 is focused by a focusing device 5 provided in the beam extraction passage 4, which is also provided in the beam extraction passage. The ion beam 2 is bent vertically and horizontally by the vertical and horizontal direction correction device 6 to correct it in a fixed direction, and the focused and direction-corrected ion beam 2 is applied to a fixed position on the target oil 7 at the entrance of the target box. The ion beam 2 that has passed through the target oil 7 is irradiated onto a target 9 in a target box 8 at a fixed position.

[Problem that the invention attempts to solve]

However, in the conventional apparatus described above, since the ion beam 2 taken out from the cyclotron 1 passes through a fixed position of the target oil 7, the part of the target oil 7 through which the beam passes is likely to overheat and burn out. 7 has a short lifespan.

[Means for solving problems]

In order to solve the above-mentioned problems, the device of the present invention deflects the ion beam 2 in the cyclotron 1 and sends it to the beam extraction passage 4, as shown in the first figure, and passes through the target oil 7 at the entrance of the target box. In a device for a deflector 3 in a cyclotron that irradiates a target 9 in a
The structure is such that an alternating current voltage _E3 is applied superimposed on the direct current voltage.

[Effect]

Since an AC voltage is applied to the deflector 3 superimposed on the DC voltage, the ion beam 2 taken out from the cyclotron 1 is deflected in the horizontal direction and scanned over the target oil 7 in the horizontal direction, so that the beam current The spatial distribution is apparently uniform,
The ion beam 2 will pass uniformly over the entire surface of the target oil 7, and the ion beam 2 that has passed uniformly over the entire surface of the target oil 7 will completely irradiate the target 9. .

〔Example〕

FIG. 1 is a simplified explanatory diagram showing the circuit and deflector of one embodiment of the device of the present invention, and FIG. 2 A, B, and C are voltage graphs thereof, respectively.

First, its configuration will be explained.

In FIG. 1, 1 is a cyclotron, 2 is its ion beam, and 3 is a deflector. The extraction passage 4 for the ion beam 2 connected to the outlet of the cyclotron 1 is the same as in FIG. 3, so it is omitted in FIG. The deflector 3 is for taking out the ion beam 2 accelerated by the cyclotron 1. The deflector 3 is composed of a negatively charged charged body 3a that curves along the path of the beam 2 and a septum 3b at a ground potential facing the charged body 3a.

The output of the high-frequency first oscillator _OSC1 is input to the primary side of the transformer T via a modulator Mod using a low-frequency second oscillator _OSC2 and an operational amplifier VCA.
The high-voltage secondary side of the transformer T is input to a Cockcroft-Walton rectifier circuit C-W, the negative output terminal of which is connected to the charged body 3a. A voltage divider Div is connected to the output side of the rectifier circuit C-W, and its output terminal is connected to a voltmeter that measures the DC component through a buffer _BUF1 and a low-pass filter _LPF1 .
The AC component is input to _V1 and also passed through a bandpass filter BPF and a rectifier RECT to a voltmeter _V2 which measures the AC component.

The output of the above low pass filter LPF ₁ is an error amplifier
It is input to the ERA and compared with the control voltage Vref, and its output is fed back to the operational amplifier VCA.
Note that the shunt SH at one end of the rectifier circuit C-W is connected to the second buffer BUF ₂ and the second low-pass filter.
Connect to ammeter A which measures the output current via LPF ₂ .

Next, the operation of this device will be explained.

The frequency of the first oscillator OSC ₁ shown in Fig. 2A is 20k.
Hz output sinusoidal voltage E ₁ is the second oscillator with modulator Mod
It is amplitude modulated with the voltage E ₂ with a frequency of 50 Hz shown in Figure 2 B of OSC ₂ , is amplified by the operational amplifier VCA, is boosted by the transformer T, is double-rectified by the Kotsuku Croft-Walton rectifier circuit CW, and becomes a DC voltage. A negative second oscillator superimposed with a low frequency AC voltage of the second oscillator.
The output voltage _E3 shown in FIG. 3 is applied to the charged body 3a of the deflector 3. Therefore, when the ion beam 2 passes between the charged body 3a and the septum 3b of the deflector 3, it is deflected in the horizontal direction, passes through the beam extraction passage 4, and scans the target oil 7 in the horizontal direction. Therefore, the spatial distribution of the beam current is apparently made uniform, and the ion beam 2 passes uniformly over the entire surface of the target oil 7. The beam 2 will be irradiated all over the target 9.

On the other hand, the above output voltage E ₃ is buffered from the voltage divider Div.
BUF ₁ is taken out and the AC component of the superimposed voltage is averaged by low pass filter LPF ₁ , the average DC voltage is indicated by voltmeter V ₁ , and the DC voltage is compared with control voltage Vref by error amplifier ERA. The error signal is fed back to the operational amplifier VCA. Therefore, the DC component of the output voltage E ₃ is automatically controlled to a constant value by the control voltage Vref, and by changing the control voltage Vref, the DC component of the output voltage E ₃ changes, and the average position of the ion beam 2 is changed. Can be adjusted.

The alternating current portion of the superimposed output voltage E ₃ is a buffer BUF ₁
After that, it flows through the 50Hz band pass filter BPF and the rectifier RECT to the voltmeter _V2 , which indicates the effective value of the AC component. Thereby, the amount of deflection of the ion beam 2 can be measured. second oscillator
By changing the output level of OSC ₂ , the magnitude of the output AC component changes and the amount of beam deflection (beam amplitude) can be adjusted.

The output current is from the shutter SH to the second buffer
The current flows through BUF ₂ and the second low-pass filter LPF ₂ to ammeter A, which causes it to swing, so that the average current can be measured.

As shown by the dotted line in Figure 1, by bypassing the modulator Mod to stop the functions of the second oscillator OSC ₂ and the modulator Mod, and by bypassing the low-pass filter LPF ₁ to stop its functions, only DC can be stabilized. It is possible to return to the power source and operate the deflector 3 in the same manner as the conventional one. It is preferable that the ion beam 2 be scanned in the vertical direction as well by an appropriate means, since the target 9 can be irradiated all over.

[Effect of idea]

As described above, according to the present invention, the deflector 3
Since an alternating current voltage is applied superimposed on a direct current voltage, the ion beam 2 taken out from the cyclotron 1 can be scanned horizontally over the target oil 7, so that it passes uniformly over the entire surface of the target oil 7. Therefore, the risk of the target oil 7 overheating and burning out is extremely reduced, and the life of the target oil 7 can be extended.

[Brief explanation of the drawing]

FIG. 1 is a simplified explanatory diagram showing the circuit and deflector of one embodiment of the device of the present invention, FIG. 2A, FIG. 2B, and FIG. 2C are graphs of the respective voltages, and FIG. 3 is a simplified plan view showing the outline of an example of a conventional device. 1... Cyclotron, 2... Ion beam,
3: Deflector, 4: Beam extraction passage,
7...target oil, 8...target box, 9...target, _E3 ...AC voltage.

Claims (1)

[Scope of utility model registration request] The deflector device in the cyclotron deflects the ion beam in the cyclotron, sends it to the beam extraction passage, passes through the target oil at the entrance of the target box, and irradiates the target in the target box. A deflector device in a cyclotron that applies voltage.