JPH03156900A - Operating method for circular accelerator and circular accelerator - Google Patents

Abstract

PURPOSE:To accelerate and accumulate a large-current beam by setting the target output values of auxiliary constituting apparatuses based on the output value of a main constituting apparatus. CONSTITUTION:A deflecting electromagnet 1 most hard to control is made a main constituting apparatus, its current is measured 6, and other electromagnets 2-4 and a high-frequency accelerating cavity 5 are controlled as auxiliary constituting apparatuses using the measured current as a reference. A control device 20 controls the electromagnet 1 with the output of a current measuring device 6. Target values of currents of the four-pole electromagnet 2, a steering electromagnet 3 and the other electromagnet, the high-frequency power and resonance frequency of the cavity are set based on the actual current value of the electromagnet 1 obtained in real time, and constituting apparatuses are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circular accelerator in which charged particles orbit in an orbit, and particularly to an operating method suitable for operating a circular accelerator.

[Prior art]

A circular accelerator is composed of an injection device for injecting charged particles into an orbit, an electromagnet such as a bending electromagnet for stably orbiting the charged particles, and a high-frequency acceleration cavity that imparts energy to the charged particles.

In a circular accelerator, each component must be controlled and operated in conjunction with each other during synchrotron acceleration and injection. This type of operation method is described in IEE Particle Accelerator Conference (1987), pages 689 to 691 (IEEE,
Particle Accelerator Coffee
renca+ 1987). This prior art relates to an operating method during synchrotron acceleration.

In synchrotron acceleration, the relationship between the magnetic field strength of the bending electromagnet (i.e., the current value flowing through the bending electromagnet), the magnetic field strength (current value) of other electromagnets, the accelerating voltage (or high-frequency power) of the high-frequency acceleration cavity, and the resonant frequency It is necessary to control them in conjunction with each other while maintaining a certain relationship between them. In conventional technology, time-varying patterns (hereinafter referred to as target patterns) such as the magnetic field strength of bending electromagnets are determined in advance before operation so as to have the above relationship, and each pattern is independently controlled to achieve each target pattern. Ta.

(Problems to be Solved by the Invention) The above-mentioned conventional technology is based on the premise that the current of electromagnets such as bending electromagnets and quadrupole electromagnets, and the acceleration voltage and resonance frequency of the high-frequency acceleration cavity can each be operated according to the target pattern.

However, with electromagnets such as bending magnets and quadrupole magnets, it is difficult to make the time change of the current follow the target pattern due to the effect that the inductance of the coil changes greatly depending on the current and the influence of the residual magnetic field of the iron core. be. If control is no longer possible according to the target pattern, the amplitude of the charged particle vibrations (betatron oscillations) in the direction perpendicular to the orbit increases, colliding with the ducts that make up the orbit, and the charged particles are lost. In this case, the more devices are interlocked, the greater the possibility that the difference between each target pattern and the actual value will influence each other and increase the amplitude of the betatron oscillation, so the amount of charged particles that are lost will increase. In other words, the amount of beam loss increases. For this reason, the conventional technology has a problem in that it is difficult to accelerate and accumulate a large current beam.

An object of the present invention is to solve the above-mentioned problems and to provide a circular accelerator operating method or a circular accelerator that enables the circular accelerator to accelerate and accumulate a large current beam.

[Means to solve the problem]

In order to achieve the above object, the present invention divides the components of the circular accelerator that are controlled during operation into main components and sub-components, and sets the target value of the output of the sub-components to the output value of the main component. determined based on

[Effect]

The operation of the present invention will be explained using synchrotron acceleration described in the prior art as an example. In this case, the main component is a bending electromagnet, the output of which is a current. Further, the subcomponents are other electromagnets and a high frequency acceleration cavity, and their control variables are current, acceleration voltage (or high frequency power), and resonance frequency, respectively. Since there is a certain relationship between the current of the bending electromagnet and the control variables of the sub-components, when controlling the bending electromagnet, which is the main component, according to a predetermined target pattern, the current of the bending electromagnet and the high-frequency acceleration The control variable of the cavity is controlled to a target value determined by the output value of the current of the bending electromagnet that is obtained from time to time during the control. This result shows that because the other electromagnets and the high-frequency acceleration cavity are always controlled while maintaining a constant relationship with the deflection electromagnet, the amplitude of the betatron oscillations does not become large, which means that the beam loss is small and the beam is stably large. Can accelerate and accumulate current.

Also, in some cases, the target value of the output of the sub-component is
It may be determined by the target value or output value of the output of other sub-component devices determined by the output value of the main component device.

An embodiment of the circular accelerator of the present invention is shown in FIG. 1 below.

The circular accelerator shown in Figure 1 is capable of accelerating electrons from 100 MeV to 5
The six circular accelerator, which is a race track type circular accelerator that accelerates up to 00 M e V, consists of a bending electromagnet 1, a quadrupole electromagnet 2. Steering electromagnet for correcting the deviation of the equilibrium trajectory 3. 6 to cancel the effect that the tune (betatron frequency per accelerator revolution) depends on the beam momentum.
Polar magnet 4. RF accelerating cavity 5° injection device for providing beam energy 17. Power supplies 7 to 11 and tuner 16 for each of component devices 1 to 5. It consists of a current measuring device 6 that measures the current of the bending electromagnet 1 and a control device 2o that controls them.

As an example of the operating method of this embodiment, an electronic 100 M e V
The case of synchrotron acceleration from 500 M e V to 500 M e V will be explained.

The deflection magnet of the accelerator shown in FIG. 1 uses iron magnetic poles, and changes the magnetic field strength from 0.3T to 1.5T to accelerate the beam. In this deflection magnet 1, the change in self-inductance is large with respect to the change in current, and it is difficult to make the current follow a target time change pattern. For this reason, the bending electromagnet that is the most difficult to control is used as the main component, its current is measured by the current measuring device 6, and the other electromagnets 2 to 4 are used as the sub-components based on this current. The high frequency acceleration cavity 5 is controlled.

In Figure 2, electrons are transferred from l OOM e V to 500 MeV.
An example of the target time change pattern of the bending electromagnet 1 when the synchrotron accelerates up to 1 is shown. The control device 20 uses the output of the current measuring device 6 to control the bending electromagnet 1 so as to follow the current pattern shown in FIG. 2 as much as possible. However, as described above, control cannot always be performed as shown in FIG. Therefore, the target values of the currents of other electromagnets such as the quadrupole electromagnet 2 and the steering electromagnet 3, the high-frequency power of the high-frequency acceleration cavity 5, and the resonance frequency are determined from the current values actually flowing through the bending electromagnets that can be obtained from time to time, and each of the above configurations is Control equipment. This control is performed by the control device 20. Hereinafter, a specific control method for each component device will be explained using FIG. 3. The bending electromagnet 1 and other electromagnets have a certain relationship via magnetic field strength or magnetic field gradient. Therefore, in this embodiment, the relationship between the current of the bending electromagnet 1 and the current of other electromagnets is determined by using the relationship between the current value and the magnetic field strength or magnetic field gradient, which are measured in advance for each.

First, the quadrupole electromagnet 2 will be explained. In Figure 3 13,
From the current measurement value 12 of the bending electromagnet 1, the magnetic field strength Ban(t
) (t: time). In a circular accelerator, it is necessary to maintain the tune at a predetermined value during operation, and the ratio between the magnetic field gradient dBe/dx (x is a direction perpendicular to the beam traveling direction) of the quadrupole magnet 2 and the deflection magnetic field strength BBM is dBe/ dX/
It is necessary to maintain BBM at a predetermined value (hereinafter referred to as rQB). Here, X indicates the deviation from the equilibrium orbit. Therefore, the target value of dBQ/dx is calculated from rQB and BBM (FIG. 3, 14).

The target value of the current of the quadrupole magnet 2 is determined from the relationship between the dBe/dx and the current measured in advance (Fig. 3, 15).
), the quadrupole electromagnet is controlled according to this target value. In this case, servo control may be performed by actually measuring the current of the quadrupole electromagnet, or open loop control may be performed as in this embodiment. This procedure has different operating conditions, dBa/d
Exactly the same procedure is performed when changing the ratio x/B.

Regarding the steering electromagnet 3 that corrects the deviation of the equilibrium trajectory, the target value of the current is determined so as to keep the ratio Bst/BaM of the magnetic field strength Bit and the magnetic field strength BBM of the deflection magnet constant (rsa), and the procedure is as follows. This is similar to the case of the quadrupole magnet described above.

Next, the hexapole electromagnet 4 for making the chromaticity ξ zero will be explained. Here, the chromaticity ξ is expressed as ξ=Δν/ΔP/P, where P is the momentum of the beam, ΔP is its width, and Δν is the width of the tune. For the hexapole electromagnet 4, the second-order magnetic field gradient d2Bsx/dx
” and the ratio of the magnetic field strength BBM of the deflection magnet d”Bsx/d x
The target value of the current is determined and controlled so as to keep the /BBM constant (r 5xa).

Finally, we will explain how to control the high frequency power and resonance frequency of the high frequency acceleration cavity from the measured values of the current of the bending electromagnet.

First, in FIG. 3, the time change of the deflection magnetic field BBH is determined from the measured value of the current of the deflection electromagnet 1, and the target value of the beam energy is determined using this result. From this target value, the energy loss due to the emitted light of the beam per revolution of the accelerator is calculated, and the target values of the resonance frequency of the acceleration cavity and the high-frequency power are determined, and each is controlled.

In the above, each electromagnet is controlled by its corresponding power source 8.
.

As described above, according to this embodiment, it is possible to simplify the control of the magnet whose current is difficult to control, so that the magnetic field control of the magnet and the high-frequency power of the high-frequency acceleration cavity can be controlled more easily and with higher precision than in the past. It is possible to perform cooperative control with the resonant frequency, and has the effect of accelerating and accumulating large currents.

The synchrotron acceleration has been described above, but the related components can be operated in a similar manner when charged particles are injected.

〔Effect of the invention〕

According to the present invention, it is possible to perform cooperative control among the magnetic field control of the magnet, the high frequency power of the high frequency acceleration cavity, the resonant frequency, the injection device, etc. more easily and with higher precision than in the past, and the control of large current It has the effect of accelerating and accumulating.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an accelerator according to an embodiment of the present invention, Fig. 2 is a diagram showing the time dependence of the measured value of the bending electromagnet current, and Fig. 3 is a diagram showing the electromagnet current and high frequency according to an embodiment of the present invention. FIG. 3 is a diagram showing a method of determining target values of power and resonance frequency.

Claims (1)

[Claims] 1. In a method of operating a circular accelerator in which charged particles circulate, the components of the circular accelerator that are controlled during operation are divided into main components and sub-components, and the target output of the sub-components is determined. A method for operating a circular accelerator, characterized in that a value is determined based on an output value of a main component. 2. In a method of operating a circular accelerator in which charged particles circulate, the components of the circular accelerator that are controlled during operation are divided into main components and sub-components, and the target value of the output of the sub-components is set to the target value of the output of the sub-components. 1. A method of operating a circular accelerator, characterized in that the method is determined based on a desired relationship between a target output value and an output value of a main component or a target value or output value of another sub-component. 3. The method of operating a circular accelerator according to claim 1 or 2, wherein the number of main components is one. 4. The method of operating a circular accelerator according to claim 1, 2 or 3, wherein the main component is a bending electromagnet, and the output of the main component is a current or a magnetic field intensity. 5. A method for operating a circular accelerator having an electromagnet, the method comprising: measuring the output of at least one electromagnet, and determining target values for the outputs of other electromagnets based on the measured value. 6. A method of operating a circular accelerator having a large number of electromagnets, wherein the large number of electromagnets has at least one measuring electromagnet whose output is measured, and the target values of the other electromagnets are equal to the target values of the other electromagnets and the measurement electromagnet. A method for operating a circular accelerator, characterized in that the determination is made based on a value or a desired relationship with a target value or output value of another electromagnet different from the other electromagnet. 7. A method of operating a circular accelerator having electromagnets, characterized in that the output of at least one electromagnet is measured, and the target value of the output of other electromagnets whose outputs are not measured is determined based on the measured value. How to operate an accelerator. 8. A method for operating a circular accelerator having an electromagnet and a high-frequency acceleration cavity, including measuring the output of at least one electromagnet and determining target values for the outputs of other electromagnets and the high-frequency acceleration cavity based on the measured value. Features: How to operate a circular accelerator. 9. In a method of operating a circular accelerator having an electromagnet and a high-frequency acceleration cavity, the output of at least one electromagnet is measured, and the output of other electromagnets whose outputs are not measured and the output of the high-frequency acceleration cavity are determined based on the measured value. A method of operating a circular accelerator characterized by determining a target value. 10. The method of operating a circular accelerator according to claim 5, 6, 7, 8 or 9, wherein the output of the electromagnet is a current. 11. The method of operating a circular accelerator according to claim 5, 6, 7, 8, or 9, wherein the output of the electromagnet is a magnetic flux density. 12. The method of operating a circular accelerator according to claim 8 or 9, wherein the output of the high-frequency acceleration cavity is at least one of high-frequency power, acceleration voltage, and resonance frequency. 13. In a circular accelerator in which charged particles circulate, the circular accelerator has a component device of the circular accelerator that is controlled during operation and a control device that controls the component device, and the component device is divided into a main component device and a sub component device. . A circular accelerator, wherein the control device determines the target value of the output of the sub-component device based on the output value of the main component device. 14. A circular accelerator having an electromagnet and a control device for controlling operation, having means for measuring the output of at least one electromagnet,
The circular accelerator, wherein the control device determines target values for outputs of other electromagnets based on the measured values. 15. A circular accelerator having an electromagnet, a high-frequency acceleration cavity, and a control device for controlling operation, having means for measuring the output of at least one electromagnet,
A method for operating a circular accelerator, characterized in that the control device determines target values for the outputs of other electromagnets and the high-frequency acceleration cavity based on the measured values.