JP3317894B2 - Vacuum electromagnet device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum electromagnet apparatus for bending a charged particle beam such as electrons and positrons traveling in a vacuum, and more particularly to an inflector for a synchrotron (also referred to as a septum electromagnet). TECHNICAL FIELD The present invention relates to a vacuum electromagnet apparatus which is easy to manufacture, can easily realize a high vacuum relatively easily, and is excellent in maintainability.

[0002]

2. Description of the Related Art For example, a synchrotron using an elliptical electron storage ring called a race track type is known. In this synchrotron, as shown in FIG. 4, two deflecting electromagnets 20A and 20B form arc-shaped orbits 12A and 12B having a radius of curvature R, and two straight lines pass between the two arc-shaped orbits 12A and 12B. Tracks 14A and 14B
To form a race-track-type orbit 10 in the vacuum vessel.

[0003] For example, four first quadrupole electromagnets 22A, 22B, 22C, 22 are provided on the linear orbits 14A, 14B.
D and four second quadrupole electromagnets 24A, 24B, 24
C, 24D and a radio frequency (RF) accelerating cavity 26 are arranged. In addition, an inflector 30 for changing the traveling direction of the incident electron beam 8 and placing the beam on the orbit 10 is arranged at an incident portion of a charged particle beam (herein, collectively referred to as an electron beam) such as an electron or a positron. Have been.

An electron beam 8 produced by an incidence accelerator (not shown) is introduced into an inflector 30 and its traveling direction is bent by a magnetic field. The electron beam whose traveling direction is bent and placed on the orbit 10 is accelerated or deflected at a desired curvature by the RF acceleration cavity 26 and the bending electromagnets 20A and 20B, and orbits the orbit 10 at a speed close to the speed of light.

[0005] In such a synchrotron, the conventional inflector 30 is entirely placed in a vacuum chamber 40 as shown in cross section in FIG. In FIG. 5, 32 is a substantially U-shaped core block, 34 is a coil, 36 is a support for suspending the inflector 30 in the vacuum chamber 40, and 38 is a cooling water pipe for cooling the coil 34. A passage 42 is an upper lid of the vacuum chamber 40, and 44 is an exhaust duct.

Here, the reason why the entire inflector 30 is arranged inside the vacuum chamber 40 is that the inflector 3
In the case of No. 0, the current is applied to the coil 34 in a pulsed manner only when the incident electron beam 8 passes to excite it to prevent heat generation. Therefore, when a metal duct such as stainless steel is placed between the magnetic poles, the eddy current is reduced. This is because the magnetic field does not enter the duct.

[0007]

However, the vacuum chamber 40 in which the inflector 30 is to be accommodated has a special shape and is inevitably increased in size, and the inflector 30 itself generates a gas that interferes with a high vacuum. Achieving the high vacuum required for synchrotrons is not easy. Further, at the time of maintenance and inspection, the vacuum tank 40 is once released to the atmosphere and the inflector 30 is taken out. After the work is completed, the inflector 30 is stored in the vacuum tank 40 again, and the vacuum is evacuated. It takes time to fix. Further, in order to cool the coil 34, it is necessary to draw cooling water into the vacuum tank 40, and there is a fear of water leakage in the vacuum tank 40. In addition, the pulse excitation also causes a problem of dielectric breakdown due to the vibration of the coil 34, and the method of supporting the coil also becomes a problem.

The present invention has been made to solve the above-mentioned conventional problems, and provides a vacuum electromagnet device which is easy to manufacture, can relatively easily realize a high vacuum, and has excellent maintainability. The purpose is to do.

[0009]

Means for Solving the Problems The present invention is the vacuum electromagnetic device for bending a charged particle beam traveling in a vacuum, disposed in a non-vacuum atmosphere, the time-varying current
An electromagnet is Ru flowed, is inserted between the magnetic poles of the electromagnet,
The cross-sectional shape is a shape having a flat surface on the outside, the inside is evacuated, and the coil of the electromagnet is disposed in close contact with the flat surface on the outside, and a vacuum duct for beam advance is provided, thereby solving the above problem. It is a solution.

[0010] Also, the pre-Symbol coil, the flat surface of the vacuum duct outer, by fixing strapped by strip material, is obtained by facilitating the support of the coil. In addition,
Make the conductor of the yl hollow and allow cooling water to flow through it
It is a thing.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 (plan view) and FIG.
As shown in FIG. 1 (a cross-sectional view taken along the line II-II in FIG. 1), a commercially available stainless steel square duct bent along the trajectory of the incident electron beam 8 is used as a vacuum duct 46, and a coil of an inflector 48 is used. , The magnetic poles 50A of the core block 50,
It is arranged between 50B.

The core block 50 has a substantially rectangular parallelepiped outer shape, and is divided into, for example, three pieces in accordance with the curvature of the vacuum duct 46.

The thickness of the vacuum duct 46 is, for example, 1 m.
m, and the material is SUS304 (electrical conductivity ρ = 1.4 ×
10 ⁶ / m).

A coil 52 composed of two parallel conductors
As shown in detail in FIG. 3, they are individually insulated by an insulating material 54 such as Kapton Mylar (manufactured by DuPont), and run in parallel along the outer side surface of the vacuum duct 46 so as to penetrate all the core blocks 50. It is arranged, and is further tied up from above by winding a fixing strip 56 such as Kapton Mylar.

The conductor of the coil 52 is, for example, hollow, through which cooling water flows.

In the figure, reference numeral 58 denotes a current introducing portion for connecting the coil 52 to a power source. The other end of the coil 52 is connected by a conductor (not shown) so that a current flows as shown by an arrow A. Have been.

The inflector 48 is excited by, for example, a half sine wave having a pulse width of 500 μs, and its repetition frequency is set to 3 Hz.

Generally, an electromagnetic wave vibrating at an angular frequency ω is
When incident on a conductor having an electric conductivity ρ and a magnetic permeability μ, the intensity at a depth d from the surface attenuates according to the following equation.

B = B 0 exp (−d / δ) (1)

Here, B and B0 are the depth d of the electromagnetic wave and the intensity at the surface, respectively. Δ is called a skin thickness and is expressed by the following equation.

Δ = {2 / (ρωμ)} (2)

The same concept can be applied to the case of a pulsed magnetic field passing through the vacuum duct 46. In the case of this embodiment, the skin thickness δ = 13 mm, and the electromagnetic wave intensity ratio B / B0 =
0.9. Note that the angular frequency ω has a pulse width of 500 μ
From seconds, it is estimated as follows.

Ω = 2π / (500 μsec × 2) = 6.28 × 10 ³ (1 / sec) (3)

Therefore, the electromagnetic wave intensity, that is, the magnetic field intensity is 1
Attenuation is about 0%, but this can be covered by increasing the power supply capacity.

Although the attenuation of the magnetic field strength can be further reduced by increasing the pulse width,
In this case, the heat value of the coil becomes a problem. That is, the amount of heat generated by the coil increases in proportion to the pulse width. In the case of the present embodiment, it is 240 W, which is the current limit of water cooling. Thus, by appropriately selecting the parameters, the attenuation of the magnetic field strength due to the eddy current can be suppressed.

In the present embodiment, since a rectangular duct having a rectangular cross section is used, the dead space is reduced by arranging it in accordance with the shape of the incident electron beam 8 which has a shape that spreads flat in the horizontal direction. And the device can be made compact. Further, the inflector 48
By bringing the magnetic poles 50A and 50B closer to the incident electron beam 8, power can also be saved. In addition, since the coil 52 made of a flat conductor is disposed on both sides of the square duct, the coil 52 can be fixed by being tied to the side surface of the vacuum duct 46, so that a separate support is not required and the support is easy. is there.

[0028] The cross-sectional shape of the vacuum duct is not limited to rectangular, square and be Rukoto are possible. Further, the method for fixing the coil is not limited to the method using the belt-shaped material.

In this embodiment, since the core block 50 is divided into three according to the curvature of the vacuum duct 46, it is easy to cope with a change in the beam trajectory, and it is possible to reduce the size. It is. Note that the number of divisions is not limited to three, and may be integrated without dividing.

In the above embodiment, the present invention is applied to a synchrotron inflector using an elliptical electron storage ring, but the present invention is not limited to this. It is apparent that the present invention can be applied to an inflector for a synchrotron using an electron storage ring of another shape and an electromagnet other than the inflector for bending a charged particle beam other than electrons and positrons traveling in a vacuum.

[0031]

According to the present invention may be a commercially available corner ducts as a vacuum duct, it is easy to manufacture the vacuum electromagnetic device. Also, the electromagnet can be arranged in a non-vacuum atmosphere, and maintenance is easy.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of the vacuum duct of the embodiment.

FIG. 4 is a plan view showing a schematic configuration of a race track type synchrotron to which one of the present invention is applied;

FIG. 5 is a cross-sectional view showing an arrangement of a conventional inflector used in the synchrotron.

[Explanation of symbols]

 Reference numeral 8: incident electron beam 10: orbit 46: vacuum duct 48: inflector 50: core block 50A, 50B: magnetic pole 52: coil 56: fixing strip

Continuation of front page (56) References JP-A-8-288126 (JP, A) JP-A-6-68996 (JP, A) JP-A-4-104500 (JP, A) JP-A-5-226100 (JP) JP-A-11-283794 (JP, A) JP-A-7-263194 (JP, A) JP-A-2000-114000 (JP, A) JP-A-6-5398 (JP, A) JP-A-5 JP-A-196799 (JP, A) JP-A-3-37999 (JP, A) JP-A-3-20700 (JP, A) JP-A-61-95298 (JP, A) JP-A-61-264650 (JP, A) JP-A-61-284100 (JP, A) Japanese Utility Model Application Laid-Open No. 5-18000 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05H 7/08

Claims (3)

(57) [Claims] 1. A vacuum electromagnet device for bending a charged particle beam traveling in a vacuum, wherein the device is disposed in a non-vacuum atmosphere and a time-varying electric current is applied.
An electromagnet that Re is inserted between the magnetic poles of the electromagnet, is shaped sectional shape to have a flat surface on the outside, inside is vacuum, the coil of the electromagnet is disposed in close contact with the flat surface of the outer, A vacuum electromagnet device comprising: a vacuum duct for beam advancement; In vacuum electromagnet apparatus according to claim 1, before Symbol coil, the flat surface of the vacuum duct outside the vacuum electromagnetic device characterized in that it is fixed strapped by strip material. (3) The vacuum electromagnet device according to claim 1 or 2.
In this case, the conductor of the coil is made hollow,
A vacuum electromagnet device characterized by flowing water.