JP2799066B2 - Accelerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an accelerator for obtaining a high energy charged particle beam (hereinafter simply referred to as a beam).

(Prior Art) In recent years, it has been found that high energy accelerators can be applied in various industrial fields. For example, in an electron synchrotron, synchrotron radiation generated by an electron beam in a magnetic field is extremely strong, high quality, and short in wavelength. For this reason, attention has been paid to the fact that this synchrotron radiation can be applied to fine processing.

 Hereinafter, an outline of the synchrotron accelerator will be described.

FIG. 7 shows an example of a synchrotron accelerator main body. Although the size varies depending on the application, the figure shows a medium-scale (about several tens of meters in diameter) ring dedicated to acceleration. In this synchrotron accelerator, a beam of relatively low energy before acceleration is generated by another accelerator (for example, linac), and is incident on the synchrotron 1 from the incident beam transport 2. The beam is composed of a plurality of bending electromagnets 4 arranged on a ring of the synchrotron 1.
(Hereinafter referred to as BM) and orbits inside the ring-shaped vacuum beam duct. The spread of the beam is controlled by a plurality of quadrupole electromagnets 5 (hereinafter, referred to as QMs) while orbiting. Further, a plurality of correction electromagnets 6 (hereinafter, referred to as SM) are provided in order to correct the distortion of the trajectory of the beam due to errors in manufacturing and installing these electromagnets. The beam is accelerated by receiving energy from the electromagnetic wave applied to the acceleration cavity 7, and when the energy reaches a predetermined energy, the beam is guided to the outside of the synchrotron 1 from the output beam transport 8.

By the way, BM4 and Q
The magnetic field generated by M5 is strengthened almost in proportion to the energy of the beam as the beam accelerates.

FIG. 8 is a time chart showing changes in current supplied to BM4 and SM6.

As shown in the figure, when the operation of the synchrotron 1 is started, an initial current is supplied from the control power supply devices respectively corresponding to BM4, QM5 and SM6. This initial current is theoretically determined according to the energy of the incident beam.

After a lapse of a predetermined time from the start of operation, a beam is incident on the synchrotron 1.

After a lapse of t _acc time from the beam incidence, the current value of BM4 is increased at a preset rate. As the current value of BM4 increases, the energy of the beam also increases. When the energy of the beam reaches a predetermined energy level, the current value of BM4 is made constant. Thereafter, the beam is taken out of the synchrotron 1.

Thus, the magnetic field generated by BM4 is strengthened almost in proportion to the increase in beam energy.

However, in the conventional accelerator, the current value supplied to SM6 for correcting the distortion of the beam trajectory remains at the initial value regardless of the current value supplied to BM4.

(Problem to be Solved by the Invention) As described above, the current for correcting the magnetic field generated by the BM at the time of beam incidence is supplied to the SM. This is extremely important for accurately performing beam incidence.

However, the current value supplied to the BM at the time of beam emission is completely different from that at the time of beam incidence.

For this reason, in the conventional accelerator in which the current value supplied to the SM remains the initial current value, there is a problem that the beam trajectory is not sufficiently corrected.

On the other hand, from the aspect of application to microfabrication, it has been an issue to improve the accuracy of the beam trajectory after emission.

The present invention has been made in view of such a point,
It is an object of the present invention to provide an accelerator capable of accurately correcting a beam trajectory at the time of beam emission.

[Means for Solving the Problems] The present invention provides a deflection electromagnet for deflecting the trajectory of a charged particle beam incident on a ring, and corrects the trajectory of the charged particle beam deflected by the deflection electromagnet. A first power supply for supplying a current to the deflection electromagnet; a second power supply for supplying a current to the correction electromagnet;
And a control means for controlling the current supplied to the deflection electromagnet by the power supply according to the acceleration of the charged particle beam, wherein a current reference value supplied to the correction electromagnet is stored when the charged particle beam is incident. Storage means, second storage means for storing a current reference value to be supplied to the correction electromagnet when the charged particle beam is emitted, and current reference values stored in the first and second storage means at a predetermined timing. The correction electromagnet includes a selection unit for selecting, and a current supply unit for supplying a current having a current reference value selected by the selection unit to the correction electromagnet.

The current reference values stored in the first and second storage means are values that can appropriately correct the beam trajectory, and are logically determined by measuring the error magnetic field generated by the electromagnet. Is done.

(Operation) In the present invention, since the current of the current reference value stored in the first or second storage means selected at a predetermined timing by the selection means is supplied to the correction electromagnet, the beam at the time of incidence and emission is supplied. The trajectory can be accurately corrected.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a control unit of a synchrotron accelerator according to one embodiment of the present invention, FIG. 2 is a block diagram showing a more detailed configuration of a control computer, and FIG.
FIG. 4 is a block diagram showing a more detailed configuration of the control power supply device.
The figure is a time chart showing the operation of the synchrotron.

As shown in FIG. 1, the control unit 100 includes a control computer 11
0, timing control device 120, communication means 130 between control computer 110 and timing control device 120, BM control power supply device
140, QM control power supply 150, and multiple SM control power supplies 16
The main part is constituted from 0.

The control computer 110 performs overall control. Based on the clock signal input from the timing control device 120, B
The M control power supply device 140 and the QM control power supply device 150 supply reference signals of currents supplied to the BM 400 and the QM 500, respectively, as a time-varying pattern. This signal is referred to herein as a pattern control reference signal. To the SM control power supply device 160, a current value supplied to the SM 600 by the power supply at the time of beam input and output is given as a constant value control reference signal. For the timing controller 120, t
Timing data specifying operation timing such as _cyc , t _M , and t _inj is transmitted via the communication means 30.

The timing control device 120 sends a timing control signal to the BM control power supply device 140 and the QM control power supply device 150 at each timing based on the timing data sent from the control computer 110, and a reference value to the SM control power supply device 160. Outputs a switching signal.

The BM control power supply device 140, the QM control power supply device 150, and the SM control power supply device 160 are based on data input from the control computer 110, a timing control signal input from the timing control device 120, and a reference value switching signal. BM400, QM500,
And supply current to SM600.

As shown in FIG. 2, a main part of the control computer 110 includes a communication control device 112 for controlling communication with the arithmetic control device 111 and the timing control device 120, an SM control power supply device 160
Digital output device 113 for outputting signals to the BM control power supply 140, a pattern memory device 115 for generating a pattern control reference signal to be output to the QM control power supply 150, and an operation panel 11 for performing various operations related to the operation of the synchrotron.
7.Digital input device 116 for inputting operations from switches provided on operation panel 117, CRT display 118 for inputting and displaying various data such as timing data, and data input from CRT display 118 are stored as data files. For example, an auxiliary memory device 119 such as a hard disk is used. Auxiliary memory device 1
An example of the timing data stored in 19 is shown in FIG.

Further, as shown in FIG. 3, a main part of the SM control power supply device 160 includes a first reference value register 161 and a second reference value register 162 which hold a constant value control reference signal provided from the control computer 110. A switch 163 that selects and outputs one of the reference values held in the first reference value register 161 and the second reference value register 162 based on a reference value switching signal input from the timing control device 120; Digital / analog (D / A) converter 164 for converting the reference value selected by the converter 163 into an analog reference signal, a power supply device 1 for supplying current to the SM600 based on the converted analog reference signal
65.

Note that the constant value control reference signal is composed of 16 bits, and the first reference value and the second reference value are identified by the leading 0 bit. That is, as shown in FIG.
The first 0 bit of the constant value control reference signal given from 0 is 0
Is held in the first reference value register 161 as the first reference value. On the other hand, when the leading 0 bit is 1, it is held in the second reference value register 162 as the second reference value.

Next, the control unit of the synchrotron thus configured
The operation of 100 will be described.

In the time chart shown in FIG. 4, in the data setting, operation data is read from the auxiliary memory device 119,
The timing data is output to the timing control device 120, the pattern reference data is output to the pattern memory device 115, and the first reference value and the second reference value are output to the SM control power supply device 160.

When an operation command is input from the operation panel 117, an operation start command is output from the control computer 110 to each power supply and the timing control device 120 from the digital output device 113, and the initial current is supplied to the BM400, QM500, and SM600. Be started. At this time, the first reference value held in the first reference value register 161 is selected by the switch 163 and output to the SM 600 as the reference value of the power supply device 165.
As the first reference value, an optimum value is determined according to the energy of the incident beam.

With a time delay of t _M from operation start command, the acceleration start signal is outputted from the timing control unit 120. The acceleration start signal is output periodically thereafter at time intervals of t _cyc until the operation command is released.

After a time delay of t _inj from the acceleration start signal, a beam incident signal is issued from the timing controller 120. The beam is incident on the synchrotron by the beam incident signal.

Further, the output of the clock signal from the timing control device 120 is started with a time delay of t _acc from the acceleration start signal. Based on this clock signal, a pattern control reference signal is output from the pattern memory device 115 to the BM control power supply device 140. The BM control power supply 140 increases the current value of the BM 400 according to the pattern control reference signal. Accordingly, the energy of the beam is increased.

A reference value switching signal is output at a timing of t _chg from the acceleration start signal. Switching device by this reference value switching signal
The output of 163 is switched to the second reference value. Thereby, the current value supplied from the SM control power supply device 160 to the SM600 is
The current value is changed to a current value suitable for beam emission.

When the energy of the beam reaches a predetermined energy level, the current value supplied from the BM control power supply device 140 to the BM 400 is made constant.

After a time delay of t _ext from the acceleration start signal, a beam emission signal is output from the timing controller 120, and the beam is extracted outside the synchrotron.

An acceleration stop signal is output from the timing control device 120 at a time delay of t _stp from the acceleration start signal. As a result, the clock signal is stopped, and the current of each electromagnet is reduced to the initial value. Further, a reference value switching signal is output, and switch 163 is switched from the second set value to the first set value.

Thereafter, each time the acceleration start signal is output, the above operation is repeated.

As described above, the current supplied to the SM 600 is switched between when the beam is incident and when the beam is emitted, so that the beam trajectory can be appropriately corrected even when the beam is emitted.

Further, by changing the reference values written in the reference value registers 161 and 162, it is possible to easily cope with an operation in which the energy after acceleration is different. Since the timing at which the reference value is switched can also be changed by the timing data given from the control computer 110 to the timing control device 120, the operation in which the repetition period changes can be dealt with by changing the reference value switching timing. In the example, the SM control power supply device is provided with the first reference value register, the second reference value register, and the switch. However, these may be provided in the control computer.

Further, the control computer may be realized by a combination of a sequence control circuit and a digital switch in addition to a so-called computer.

[Effect of the Invention] According to the accelerator of the present invention, the current of the current reference value stored in the first or second storage means, which is selected at a predetermined timing by the selection means, is supplied to the correction electromagnet. A current can be applied to the correction electromagnet so as to appropriately correct the beam trajectory at the time of beam emission and at the time of beam emission, and the emitted beam can be controlled with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control unit of a synchrotron accelerator according to an embodiment of the present invention, FIG. 2 is a block diagram showing a more detailed configuration of a control computer, and FIG. FIG. 4 is a block diagram showing the detailed configuration, FIG. 4 is a time chart showing the operation of the synchrotron, FIG. 5 is a diagram showing an example of timing data stored in the auxiliary memory device and given to the timing control device after startup, and FIG. The figure shows the constant value control reference signal held in the reference value register,
FIG. 7 is a diagram showing a configuration of a synchrotron accelerator main body, and FIG. 8 is a time chart showing a conventional operation. 1 ... Synchrotron, 4,400 ... Bending electromagnet (B
M), 5,500: 4-pole electromagnet (QM), 6,600: Correcting electromagnet (SM), 100: Control unit, 110: Control computer,
120 ... timing control device, 130 ... communication means, 140 ...
… BM control power supply, 150… QM control power supply, 160… SM
Control power supply device, 111 arithmetic operation control device, 113 digital output device, 115 pattern memory device, 119 auxiliary memory device, 161 first reference value register, 162 second reference value Register, 163 ... Switcher 163, 164 ... Digital / Analog (D / A) converter, 165 ... Power supply.

Claims (1)

(57) [Claims] A deflection electromagnet for deflecting the trajectory of the charged particle beam incident on the ring; a correction electromagnet for correcting the trajectory of the charged particle beam deflected by the deflection electromagnet; and a current supply to the deflection electromagnet. A first power supply for supplying current to the compensating electromagnet;
And a control means for controlling a current supplied to the deflection electromagnet by the power supply according to the acceleration of the charged particle beam. A first memory for storing a current reference value supplied to the correction electromagnet when the charged particle beam is incident. Storage means; second storage means for storing a current reference value to be supplied to the correction electromagnet when the charged particle beam is emitted; and current reference values stored in the first and second storage means at a predetermined timing. An accelerator comprising: selecting means for selecting; and current supplying means for supplying a current having a current reference value selected by the selecting means to the correction electromagnet.