JPH11283798A - Charged particle beam accelerator and adjustment method of charged particle beam storage ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct relatively large deviation from a design value of the resonance frequency of a high-frequency cavity by providing a gap length adjusting mechanism to vary the gap length of a gap part for an acceleration means to define the high-frequency cavity including the gap part to excite a high-frequency electric field in parallel with the traveling direction of a charged particle beam in another passage. SOLUTION: An acceleration means 10 is composed of a pair of high rigidity parts 11A, 11B, a low rigidity part 12, a copper block 13 and flange parts 14. The end surfaces of the high rigidity parts 11A, 11B are arranged perpendicularly to a circulating track 40 and define a gap part 15 having a gap length of (d). The flange parts 14 are joined to a beam transporting pipe line 25 mounted to a deflection electromagnet 20A through a vacuum bellows 26. The deflection electromagnet 20A and an end plate 12A are connected together by multiple gap length adjusting mechanisms 50 composed of male screws 50B, 50C and combining members 50A for which female screws are formed in both their ends. The end plate 12A is deformed by rotating the combining members 50A and thereby, the gap length (d) of the gap part 15 is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charged particle beam accelerator and a method for adjusting a charged particle beam storage ring, and more particularly to a charged particle beam accelerator having a high-frequency cavity for accelerating a charged particle beam and a charged particle beam storage ring. Regarding the adjustment method.

[0002]

2. Description of the Related Art In an accelerating device having a high-frequency cavity for accelerating a charged particle beam, due to a manufacturing error or the like,
The resonance frequency of the high-frequency cavity may be different from the design value.
To correct the deviation of the resonance frequency, a copper block called a tuner is used. By inserting a copper block into the high-frequency cavity, its resonance frequency can be fine-tuned.

[0003]

If the resonance frequency of the high-frequency cavity greatly deviates from the design value, there may be cases where the deviation of the resonance frequency cannot be completely corrected by the fine adjustment using the tuner.

An object of the present invention is to provide a charged particle beam accelerator capable of correcting a relatively large deviation from a design value of a resonance frequency of a high-frequency cavity for accelerating a charged particle beam.

Another object of the present invention is to provide a method of adjusting a charged particle beam storage ring capable of correcting a relatively large deviation of a resonance frequency of a high-frequency cavity from a design value for accelerating a charged particle beam. That is.

[0006]

According to one aspect of the present invention, a beam transport conduit defining a passage through which a charged particle beam passes, and a passage in the beam transport conduit coupled to the beam transport conduit. An accelerating means for defining a high-frequency cavity including a gap for exciting a high-frequency electric field parallel to the traveling direction of the charged particle beam into the other passage while defining another passage communicating with the charged particle beam; and A charged particle beam accelerator having a gap length adjusting mechanism for changing a gap length is provided.

In accordance with another aspect of the present invention, a process for constructing a charged particle beam storage ring including acceleration means defining a high frequency cavity having a gap for exciting a high frequency electric field parallel to the direction of travel of the charged particle beam. Adjusting the resonance frequency of the high-frequency cavity by changing the gap length of the gap of the accelerating means.

The resonance frequency of the high-frequency cavity can be adjusted by changing the gap length of the gap.

[0009]

FIG. 1 shows a schematic plan view and a block diagram of an electron storage ring according to an embodiment of the present invention. The two bending electromagnets 20A and 20B form two semi-circular electron trajectories.
A racetrack-type orbital track 40 is formed in the vacuum vessel by communicating with the straight track. The acceleration means 10, the quadrupole magnet 21A, and the
Are arranged, and the current monitor 23, the quadrupole electromagnet 21B, and the inflector 24 are arranged on the other straight track.

[0010] High-frequency power is supplied from a high-frequency power supply 9 to the acceleration means 10. A DC current is supplied from the DC power supply 30 to the bending electromagnets 20A and 20B, and a DC current is supplied from the DC power supply 31 to the quadrupole electromagnets 21A and 21B. A pulse current is supplied to the part beta 22 and the inflector 24 from pulse power supplies 32 and 34, respectively.

The acceleration means 10 accelerates the electron beam orbiting along the orbit 40. Quadrupole electromagnets 21A and 2
1B generates a quadrupole magnetic field and gives a focusing force to the electron beam. Although not shown in FIG. 1, a hexapole electromagnet for generating a hexapole magnetic field for correcting the aberration of the electron beam, and an octopole for generating an octupole magnetic field for providing a focusing force depending on the amplitude of the betatron oscillation. An electromagnet may be arranged.

The current monitor 23 measures the current caused by the electron beam orbiting the orbit 40. Inflector 24
Puts an electron beam emitted from an incidence accelerator (not shown) on an orbit close to the orbit 40. The electron orbit immediately after the introduction does not exactly coincide with the orbit 40. When the electron beam placed on the orbit close to the orbit 40 is first corrected in the orbit when passing through the perta beta 22, the electron beam is placed on the orbit 40. While the electron beam orbits along the orbit 40, the inflector 24 and the perta beta 22 have stopped functioning.

The acceleration means 10 defines a high-frequency cavity containing a part of the orbit 40. When high-frequency power is supplied from the high-frequency power supply 9 into the high-frequency cavity, a high-frequency electric field is excited therein. An orbiting electron beam is accelerated in synchronization with the high-frequency electric field, and a high-energy electron beam is accumulated. Since the electron beam orbiting along the orbit 40 has a speed close to the speed of light, even if it is accelerated by a high-frequency electric field, its speed hardly changes and its mass increases.

FIG. 2 is a sectional view of the acceleration means 10. The acceleration unit 10 includes a pair of high-rigidity portions 11A and 11B, a low-rigidity portion 12, a copper block 13, and a flange portion 14. These components are formed of, for example, oxygen-free copper or aluminum.

The high-rigidity portions 11A and 11B have an annular shape, are interlinked with the orbital track 40, and are disposed so that their end faces face each other. Opposite end faces of the high-rigidity portions 11A and 11B are disposed perpendicular to the orbital track 40 and define a gap portion 15 having a gap length d.

The low-rigidity portion 12 includes end plates 12A and 12B and an outer peripheral plate 12C. The end plates 12A and 12B have a disc-like shape having a through hole at the center, and are continuous with the high-rigidity portions 11A and 11B at their inner peripheral edges. The high-rigidity portion 11A, the end plate 12A, and the high-rigidity portion 11B
And the end plate 12B are integrally formed. Outer plate 1
2C connects the end plates 12A and 12B at their outer edges. High rigidity parts 11A and 11B and low rigidity part 1
2 defines a high frequency cavity 16 including a gap 15.

The radius of the outer peripheral edge of the end plates 12A and 12B is
For example, the gap length d of the gap 15 is, for example, about 4 cm.

The low-rigidity portions 12 are high-rigidity portions 11A and 11B.
The thickness of the high rigidity portions 11A and 11A
B has lower rigidity than B. For this reason, it is relatively easily deformed by an external force.

The tip of the copper block 13 is inserted into the high-frequency cavity 16 through a through hole provided in the outer peripheral plate 12C. By changing the insertion amount, the high-frequency cavity 16
Can be finely adjusted.

The flange portion 14 is mounted near the inner peripheral edge of the outer end face of the high rigidity portion 11A. The flange portion 14 is connected via a vacuum bellows 26 to a beam transport conduit 25 attached to the bending electromagnet 20A. The orbit 4 is formed by the beam transport conduit 25, the vacuum bellows 26, the flange portion 14, and the high-rigidity portions 11A and 11B.
The path of the charged particle beam along 0 is defined.

A plurality of gap length adjusting mechanisms 50 composed of turnbuckles are connected between the bending electromagnet 20A and the vicinity of the inner peripheral edge of the end plate 12A. Each gap length adjusting mechanism 50
Is composed of male screws 50B and 50C, and a connecting member 50A having female screws formed at both ends. The male screw 50B is fixed to the bending electromagnet 20A, and the male screw 50C is fixed near the inner peripheral edge of the end plate 20A of the acceleration means 10. The male screw 50B is fixed to the yoke of the bending electromagnet 20A, for example. The connecting member 50A has a male screw 50 at both ends.
B and 50C.

One of the external threads 50B and 50C is a right-hand thread and the other is a left-hand thread. By rotating the connecting member 50A, the distance between the external threads 50B and 50C can be changed. The end plate 1 is rotated by the rotation of the connecting member 50A.
2A is deformed, and the gap length d of the gap 15 changes.
The gap between the beam transport conduit 25 and the flange 14 also changes with the change in the gap length d, but this change is absorbed by the vacuum bellows 26.

The high frequency power supply 9 shown in FIG.
High-frequency electric power is supplied to the inside 6, and a high-frequency electric field parallel to the direction of the orbit 40 is excited in the gap 15. By this high-frequency electric field, the charged particle beam orbiting along the orbit 40 is accelerated.

The resonance frequency f ₀ of the high-frequency cavity 16 is represented by the following _equation :

[0025]

F ₀ = 1 / (2π (LC) ^−1/2 ) (1) When the gap length d of the gap 15 is changed, the capacitance component formed in the gap 15 changes, and the resonance frequency f ₀ changes. When the gap length d is increased, the resonance frequency f ₀ increases, and when the gap length d is reduced, the resonance frequency f ₀ decreases.

The capacitance component C of the high-frequency cavity 16
5 largely depends on the capacitance component formed. Therefore,
By changing the capacitance component formed in the gap 15, the resonance frequency of the high-frequency cavity 16 can be changed more greatly than when the insertion amount of the copper block 13 is changed. Therefore, even when there is a large manufacturing error that cannot be corrected by the copper block 13 alone, the resonance frequency can be corrected by changing the gap length d of the gap 15.

In the above embodiment, the gap length adjusting mechanism 50
Although the case where the turnbuckle is used has been described, another length adjusting mechanism may be used. Further, in the above embodiment, the case where the gap length adjusting mechanism 50 connects the bending electromagnet 20A and the end plate 12A of the acceleration means 12 has been described, but other portions may be connected. For example, the beam transport conduit 25 and the flange 14 may be connected. Further, the outer end faces of the high-rigidity portions 11A and 11B may be connected to each other.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0029]

As described above, according to the present invention,
By changing the gap length of the gap of the high-frequency cavity, the resonance frequency of the high-frequency cavity can be changed in a relatively wide range. Therefore, it is possible to correct a relatively large deviation of the resonance frequency due to a manufacturing error.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and a block diagram of a charged particle beam storage ring.

FIG. 2 is a sectional view of an acceleration unit according to the embodiment.

[Explanation of symbols]

 9 High frequency power supply 10 Acceleration means 11A, 11B High rigidity part 12 Low rigidity part 12A, 12B End plate 12C Outer peripheral plate 13 Copper block 14 Flange part 15 Gap part 16 High frequency cavity 20A, 20B Bending electromagnet 21A, 21B Quadrupole electromagnet 22 Parta beta 23 Current Monitor 24 Inflector 25 Beam transport line 26 Vacuum bellows 30, 31 DC power supply 32, 34 Pulse power supply 40 Orbital track 50 Gap length adjusting mechanism 50A Connecting member 50B, 50C Male screw

Claims (5)

[Claims] 1. A beam transport conduit defining a passage through which a charged particle beam passes, and another passage coupled to the beam transport conduit and communicating with a passage in the beam transport conduit. An acceleration means for defining a high-frequency cavity including a gap for exciting a high-frequency electric field parallel to the traveling direction of the particle beam into the other passage; and a gap length adjusting mechanism for changing a gap length of the gap. Charged particle beam accelerator. 2. The low-rigidity member having a lower rigidity than the high-rigidity portion, wherein the acceleration means defines a pair of high-rigidity portions defining a pair of end surfaces of the gap and the high-rigidity portion together with the high-rigidity portion. The charged particle beam accelerator according to claim 1, wherein the gap length adjusting mechanism changes the gap length of the gap by deforming the low-rigidity portion. 3. The apparatus according to claim 1, further comprising: a support fixed to the beam transport conduit; and a vacuum bellows for keeping a connection between the beam transport conduit and the acceleration means airtight. 3. The charged particle beam accelerator according to claim 2, wherein one of the high-rigidity portions of the acceleration means and the support are connected to each other, and a gap between the two is changed to change a gap length of the gap. 4. A deflection electromagnet which forms a charged particle beam storage ring together with the beam transport conduit and the acceleration means, wherein the support is a yoke of the deflection electromagnet.
3. A charged particle beam accelerator according to claim 1. 5. A step of configuring a charged particle beam storage ring including acceleration means defining a high frequency cavity having a gap for exciting a high frequency electric field parallel to the direction of travel of the charged particle beam; Adjusting the resonance frequency of the high-frequency cavity by changing the gap length of the portion.