JPS63138697A - Radio frequency accelerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention relates to a high-frequency accelerator equipped in a charged particle accelerator such as a synchrotron that accelerates charged particles such as proton (proton) 9-heavy ions. More specifically, the present invention relates to an 0NE-GAP type high frequency accelerator, and particularly to a high frequency accelerator designed to improve acceleration efficiency.

(Prior art) A synchrotron, which is a type of charged particle accelerator, consists of a circularly arranged deflection magnet and a focusing electromagnet, a doughnut-shaped vacuum vessel that passes through the gap between these magnetic poles, a high-frequency accelerator, a vacuum pump, etc. There is something configured. In this configuration, the magnetic field and acceleration frequency are changed in response to an increase in particle energy, so that the particles are accelerated while being maintained on a circular orbit with a constant radius.

To briefly describe its operation in detail, a charged particle beam pre-accelerated by a linac (linear accelerator), which is an injector, is incident on a high vacuum ring (vacuum container), and the magnetic field generated by the magnet is applied to the charged particle beam. The particles are caused to run in a nearly constant trajectory, causing them to orbit inside the container. The charged particle beam synchronized with a high frequency high voltage that is an integral multiple of the rotational frequency during this revolution is repeatedly subjected to acceleration force, and the energy increases accordingly. In this case, the N magnet is excited to keep the average orbital radius constant during the orbit, but in the case of electrons, if the incident energy is, for example, 20 MeV, it has already reached 99.97% of the speed of light. In the case of protons, it is 10 MeV, which is 14.48 of the speed of light.
%, and 100MeVr accelerated is 42.8
2%, and 87.50% at 1 GeV. In other words, unlike heavy particles such as electrons, heavy particles such as protons must be highly accelerated, and therefore, as a high-frequency accelerator, their resonant frequency must be significantly modulated.

Generally, a high-frequency accelerator installed in a synchrotron that accelerates heavily charged particles such as protons and heavy ions is a ferrite-loaded high-frequency accelerator that uses a ferrite-loaded coaxial inductance as an LC resonator. In this resonator, a method is used in which a direct current bias magnetic field is applied to the ferrite to reduce its magnetic permeability, thereby gradually lowering the inductance, thereby raising the resonant frequency and achieving tuning.

This type of ferrite-loaded high-frequency accelerator will be described in detail below. That is, as shown in FIG.
A ferrite 3 is loaded between the ferrite 3 and the outer cylinder 2 to form a 1/4 wavelength coaxial resonator 4. Two of these resonators 4 are coupled with opposite phases to form a cavity. It is used as a high frequency accelerator. There are several means for applying a DC bias magnetic field to the ferrite 3 in this configuration.

To apply a DC bias magnetic field to the ferrite 3, there are two methods: passing a current through the cavity body, and winding a conductor around the ferrite 3 several times and passing the current through the conductor.
Furthermore, there are two types, the 0NE-GAP method and the TWO-GAP method, depending on how the bias current is passed.

The 0NE-GAP type high frequency accelerator will be described below.

Figure 4 shows the US's 0mn1tr'On research and West Germany's G
1 is a schematic diagram of an ONE, -GAP type high frequency accelerator used in the SI heavy ion synchrotron project.

In FIG. 4, a bias winding 115 made of a bus bar is wound several turns so as to surround the left and right ferrite rings 3 in a figure eight direction, and a bias power supply 6 is connected to the bias winding 115. In the figure, 7 is a beam trajectory, 8 is an acceleration gap, 9 is a choke winding, 10 is a high frequency amplifier, and 11 is a Bl source.

In the above, the bias winding 115 also has the function of inducing a high frequency voltage of opposite phase, and by installing an appropriate number of turns on the outer circumferential side of the ferrite ring 3, the bias winding 115 can increase the power capacity of the bias power supply 6 for the bias current circuit. can be small.

However, when the high-frequency accelerator having the configuration shown in FIG. 4 is installed and operated within a synchrotron, it is carried out as follows. That is, according to the synchrotron operating program, the bias current is varied and adjusted to increase from the initial acceleration frequency to the final acceleration frequency. In this case, the frequency at the time of acceleration start is started with a bias current of zero, and the bias current is gradually increased to raise the resonant frequency. Then, control is performed so that the bias current reaches its maximum value at the maximum resonance frequency at the end of acceleration. The operation program is related to the rate of change of the magnetic flux density of the deflecting magnet, the accelerating voltage, the accelerating voltage phase, etc. Also, since changes in the bias current deteriorate particle acceleration efficiency, bias current control is required. requires high control accuracy.

As described above, the bias current requires high control accuracy, but this bias current changes from zero to the maximum current (usually 1000 Afj! degrees).
The bias power supply 6 is required to operate stably over this entire range. However, with this type of large capacity power supply (bias power supply 6), it is difficult to expect stability over the entire range.
Normally, it operates stably in the range of 100% to 10% of the rated current, but becomes unstable in the range of 10% or less of the rated current, making acceleration control difficult at low bias currents and reducing acceleration efficiency. There was a problem.

(Problems to be Solved by the Invention) As described above, in the conventional high frequency accelerator, the bias current requires high control accuracy;
Since the 'R power supply device also has characteristic limits, its operation becomes unstable, especially at low bias currents, leading to a decrease in acceleration efficiency.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high frequency accelerator that eliminates the instability of bias current at low bias currents and has high acceleration efficiency.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems and achieve the object, the present invention is constructed as follows. That is, a ferrite is provided between the inner tube and the outer tube, and a bias winding is wound around the outer periphery of the ferrite to construct a quarter wavelength coaxial resonator. Let's connect and connect both valve vibrators! ! By applying aN pressure between
proton.

A high frequency accelerator for accelerating charged particles such as heavy ions is characterized in that a sub-bias winding separate from the bias winding is wound around the outer periphery of the ferrite.

(Function) The main bias winding and the sub-bias winding are configured in this way, and a current is passed through the sub-bias winding so as to be constantly excited in the direction opposite to that of the main bias winding. As a result, the current flowing through the main bias winding becomes a current value higher than the minimum value, so the main bias current increases from zero to maximum within the stable operating range of the power supply (100% to 10% of the rated current). Even the current can be controlled with high precision.

(Embodiment) An embodiment of the high frequency accelerator according to the present invention will be described below with reference to FIG. 1, in which the same parts as in FIGS. 3 and 4 are given the same reference numerals. That is, in this embodiment, a ferrite 3 is provided between an inner cylinder 1 and an outer cylinder 2, and a bias winding (main bias winding) 5 is wound around the outer periphery of the ferrite 3, so that the ferrite 3 has a 1/4 wavelength. A coaxial type resonator 4 is constructed, and two of these resonators 4 are coupled with each other facing each other in opposite phases. In the figure, resonators 4 are configured on the left and right sides of the center, respectively. Here, the bias winding (main bias winding) 5 is cross-linked and coupled between both valve oscillators 4, 4 so as to cancel out high frequencies, and is connected to a bias power supply (main bias power supply) 6. There is.

An acceleration gap 8 extending from the beam trajectory 7 is provided at the junction of the inner cylinders 1 of the two valve vibrators 4.4.

Further, a choke winding 9 connected to a Bri source 11 is wound around a part of the ferrite 3, and the power induced in this choke winding 9 is given to a high frequency amplifier 10, and the output of this high frequency amplifier 10 is By being introduced into the inner cylinder 1 on one side of the acceleration gap 8, charged particles such as protons and heavy ions within the beam trajectory 7 are accelerated.

Furthermore, a sub-bias winding 12 is wound around the outer periphery of the ferrite 3 at the same position as the bias winding (main bias winding) 5, and this sub-bias winding 12 is a sub-bias winding that can supply a stable constant current. It is connected to the power supply 13.

Here, the relationship between the main bias winding 5 and the sub bias winding 12 will be explained. That is, as shown in Figure 2,
The conductor 5a of the main bias winding 5 and the conductor 12a of the sub bias winding 12 are supported and fixed by a support 15 via an insulator 14. In this case, the sub bias winding 1
The amount of current applied to the main bias winding 5 is approximately 10% of the amount of current applied to the main bias winding 5. 12 conductors 12a
The cross section of the conductor may be smaller than that of the conductor 5a of the main bias winding 5.

Next, the operation of this embodiment configured as described above will be explained. That is, the minimum current (about 10% of the rating) If) that guarantees the stability of the rating of the bias winding source 6 is applied from the auxiliary bias power supply 13 to the auxiliary bias winding 12 in the opposite direction to the main bias winding m5. Flow. As a result, ferrite 3
is constantly excited in the opposite direction to the excitation by the main bias winding 5, the excitation is canceled out, and the ferrite 3 is in a non-excited state.

This state becomes the resonance frequency at the start of acceleration, and acceleration is started according to the synchrotron operation program. From this state, the current from the main piezoelectric mirror m6, that is, the bias current, is increased to raise the resonant frequency, and the bias current is increased to the maximum required value for control.

In the above control, it is possible to carry out the process from zero bias current to the maximum value of the bias current at the maximum resonance frequency within a current range that guarantees the stability of the rated bias N source 6. Since the bias current is stable over the entire range, the acceleration sub-section becomes easy and the acceleration efficiency does not deteriorate.

As shown in FIG. 2, the conductor 5a of the main bias winding 5 and the conductor 12a of the sub bias winding 12 are close to each other in the entire circuit, so that the excitation by the main bias winding 5 and the conductor 12a of the sub bias winding 12 are close to each other. Since the excitation by 12 is efficiently canceled out in all parts of the winding and the cavity, the above-mentioned stable acceleration control is realized without affecting other elements.

The present invention is characterized in that a sub-bias winding is provided on the outer periphery of the ferrite in order to offset the excitation effect of the bias winding at low current, and the shape of the sub-bias winding is shown in FIG. The shape is not limited, and various shapes can be applied.

Furthermore, the number of turns in the sub-bias winding may be reduced, or the number of turns may be increased since the sub-bias winding is constantly excited and is not affected by inductance. The invention can be modified in various ways without departing from the gist of the invention.

[Effects of the Invention] As described above, in the present invention, by providing the auxiliary bias winding around the ferrite outer circumference in order to offset the excitation effect of the bias winding at low current, the stable operating range (rated current (in the range of 100% to 10% of It is possible.

4. Brief explanation of the drawings Fig. 1 is a diagram showing the configuration of an embodiment of the high frequency accelerator according to the present invention.
FIG. 2 is a detailed view of the main parts of the same embodiment, FIG. 3 is a diagram showing the principle of the high frequency accelerator, and FIG. 4 is a diagram showing the configuration of the high frequency accelerator to which the present invention is applied.

1...Inner cylinder, 2...Outer cylinder, 3...Ferrite, 4
... Resonator, 5... Bias winding, 6... Bias power supply, 12... Sub-bias winding, 13... Sub-bias power supply.

Applicant's agent: Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] A ferrite is provided between the inner tube and the outer tube, and a bias winding is wound around the outer periphery of the ferrite to construct a quarter wavelength coaxial resonator. In a high frequency accelerator in which charged particles such as protons and heavy ions are accelerated by coupling and applying a high voltage between the inner cylinders of both resonators, a A high frequency accelerator characterized by having a secondary bias winding wound thereon.