JPS62150802A - Superconducting electromagnet for deflecting charged particles - Google Patents

Abstract

PURPOSE:To reduce the size and to enhance the performance of a high magnetic field superconducting electromagnet by disposing a shielding spacer with which electromagnetic wave emitted in a tangential direction with respect to the propagating direction of charged particles to be deflected collides in noncontacting state with a coil cooling tank in a charged particle passing orbit. CONSTITUTION:A hollow cylindrical coil cooling tank 6 in which the outer surface of an outside peripheral wall 6b and the outer surfaces of longitudinal end walls 6c, 6c' are covered with heat insulating layers 7 is concentrically disposed in contact with a particle orbit 3 disposed at the center on the outer periphery of the orbit 3. A shielding spacer 8 with which electromagnetic wave emitted in a tangential direction with respect to the propagating direction of charged particles to be defected collides is disposed in noncontacting state with the tank 6 in the orbit 3. Since the coil cooling tank is provided in contact with the orbit, the size of the outer diameter including cooling means can be shortened in the distance that the layer is not provided inside. Since the superconducting coil is provided near the orbit, a coil load becomes small, and the coil can be reduced in size.

Description

[Detailed description of the invention] This invention is a circular accelerator, a storage ring, a 5OR (
The present invention relates to superconducting electromagnets used to deflect charged particles in synchrotron orbital radiation devices, ion implantation devices, etc.

[Technical background and subject of this invention■]

The charged particle deflection electromagnets used in the devices mentioned above are generally of the normal conduction type, with a coil wound around an iron core, but with the normal conduction method, it is difficult to create a smaller and more powerful deflection electromagnet. Therefore, in order to eliminate this problem, the present inventors devised a superconducting dipole electromagnet with a curvature perpendicular to the direction of the magnetic field, and filed a patent application in 1983.
This was proposed by No.-249285. FIG. 4 shows an example of this, in which two saddle-shaped superconducting coils 2 are placed across the outer periphery of a beam duct 1 so as to face each other, and a curvature is given to a saddle-shaped dipole electromagnet.

By the way, superconducting electromagnets exhibit superconductivity only at temperatures close to absolute zero. Therefore, it is necessary to store the coil in the taliostat together with a cryogenic refrigerant liquid such as liquid helium, but if the structural design of the electromagnet including the cooling means is poor, various inconveniences may occur. . For example, as shown in FIG. 5, a beam duct 1 surrounds the outer periphery of a charged particle passing trajectory (hereinafter referred to as a particle trajectory) 3, and a hollow annular cooling device surrounded by a heat insulating layer 4, 5 is placed around the outer periphery of the beam duct 1. It is relatively easy to think of a structure in which the tanks 6 are arranged concentrically and the superconducting coils 2 are attached to the outer periphery of the inner peripheral wall 6a of the tank, but if the heat insulating layers are arranged in double radial direction in this way, the electromagnet The outer diameter becomes larger, which is disadvantageous in terms of installation space and handling.

In addition, in this case, it is necessary to take into account the thickness of the inner heat insulating layer 4, that is, to apply a predetermined uniform magnetic field to the track 3 in a large space increased by the thickness, so it is necessary to apply a uniform magnetic field to the track 3. The current density and the magnetic field limited to the wire also increase. Therefore, the characteristics required for the superconducting coil wire used will naturally become stricter.

Therefore, as a countermeasure to the above-mentioned problem, it is conceivable to eliminate the heat insulating layer 4 in FIG. 5 and to arrange the cooling tank 6 in contact with the particle trajectory 3. However, when charged particles are deflected by a magnetic field, radiated electromagnetic waves are generated in the deflection section. For example, when electrons are made to orbit at a speed close to the speed of light, synchrotron radiation consisting mainly of If is tangent to the particle orbit, then
The synchrotron radiation hits the cooling tank and is converted into thermal energy.
Increase the temperature of the cooling bath. As a result, the evaporation of the cryogenic refrigerant liquid such as liquid helicum stored in the cooling tank is accelerated, increasing the running cost of the apparatus. In other words, simply arranging the cooling tank in contact with the particle trajectory cannot eliminate the disadvantage in terms of running costs.

This invention has been made in view of the above, and aims to simultaneously satisfy the requirements for miniaturization, high performance, and reduction in running costs of high-field superconducting electromagnets.

[Means to solve the problem]

In order to deal with the above-mentioned problems, the present invention provides a superconducting dipole electromagnet in which charged particles are deflected by a magnetic field perpendicular to the traveling direction, as shown in FIGS. A hollow cylindrical coil cooling tank 6 whose outer surface of the outer circumferential wall 6b and the outer surface of the end wall 6C16C' in the direction of extension are covered with a heat insulating layer 7 is arranged concentrically in contact with the orbit 3, and further, inside the particle orbit 3. A shielding spacer 8 is disposed in a non-contact state with respect to the tank 6 for colliding electromagnetic waves emitted in a direction tangential to the traveling direction of charged particles to be deflected. Reference numeral 6a denotes an inner peripheral wall of the tank 6 surrounding the rail tank 3, and the superconducting coil 2 is attached to the outer peripheral surface of the wall.

The shielding spacer 8 shown in the figure has a semicircular cross section, but the shape is not particularly limited as long as it can block the traveling path of the radiated electromagnetic waves. For example, a cylindrical spacer or the like may be used.

The purpose of this shielding spacer is to reduce heat intrusion into the cooling tank 6 caused by radiated electromagnetic waves, so it is made of a metal with good heat conductivity such as copper, aluminum, iron, or stainless steel. It is desirable to allow heat to escape quickly from both ends. To dissipate heat from both ends, as shown in Figure 2, both ends of the spacer are
It is conceivable to connect it to a portion of the heat insulating layer 7 that covers the end walls 5c, 5c'. In this case, the heat insulating layer 7 may be a vacuum heat insulating layer, a heat reflective layer, etc. as long as the wall material is made of a material with good heat conductivity, but it may be a heat insulating layer with self-cooling ability using liquid nitrogen as a cooling source. In this case, the heat dissipation of the spacer becomes very good.

In addition, heat from the spacer can also be released by supporting both ends of the spacer with a heat sink that is separate from the wall material of the heat insulating layer and faces the particle trajectory section from outside the device.

[Operation/Effect] In the electromagnet of the present invention described above, since the coil cooling tank is provided in contact with the particle orbit, there is no heat insulating layer inside, so the outer diameter including the cooling means can be shortened. can.

Moreover, since the superconducting coil is close to the particle trajectory, the coil load is also reduced, and furthermore, the coil can be made smaller, so that the overall volume can be further reduced.

Furthermore, it is necessary to maintain a high vacuum inside the particle orbit, but unlike the structure shown in Figure 4, where the vacuum is maintained by a beam duct, the vacuum is maintained by a cooling tank with double inner and outer peripheral walls, so it is economically possible to maintain a high vacuum. It is also possible to increase the degree.

In addition, the shielding spacer prevents the radiated electromagnetic waves from colliding with the coil cooling tank and prevents the temperature of the cooling tank from rising due to the electromagnetic waves, reducing the amount of heat entering the cooling tank and eliminating wasteful evaporation of the refrigerant liquid in the tank. This has the effect of suppressing the

[Brief explanation of drawings]

Fig. 1 is a perspective external view showing an example of the electromagnet of the present invention, Fig. 2 is a side sectional view of the electromagnet in its unfolded state, Fig. 3 is a sectional view taken along line In-III in Fig. 2, and Fig. 4. 5 is a perspective view of a dipole superconducting electromagnet having a curvature perpendicular to the direction of the magnetic field, and FIG. 5 is a sectional view of a generally considered superconducting electromagnet for deflecting charged particles including a cooling means. 2... Superconducting coil, 3... Particle trajectory, 6... Coil cooling tank, 6a... Inner circumferential wall, 6b... Outer circumferential wall, 6 Ct 5c/... End wall, 7...・・insulation layer,
8... Spacer for shielding radiated electromagnetic waves Patent applicant: Sumitomo Electric Industries, Ltd. Agent: Kama 1) Text - Figures 1, 2, and 3

Claims (2)

[Claims] (1) In a superconducting dipole electromagnet in which charged particles are deflected by a magnetic field perpendicular to the direction of travel, a hollow space is provided around the outer periphery of the charged particle passage trajectory located at the center, and the outer surface of the outer circumferential wall and the outer surface of the longitudinal end wall are covered with a heat insulating layer. A cylindrical coil cooling layer is arranged concentrically in contact with the orbit, and a shielding spacer is further provided in the charged particle passing orbit, on which electromagnetic waves emitted in a direction tangential to the traveling direction of the charged particles to be deflected collide. A superconducting electromagnet for deflecting charged particles, characterized in that the are arranged in a non-contact state with respect to a coil cooling tank. (2) The superconducting electromagnet for charged particle deflection according to claim (1), wherein both ends of the shielding spacer are connected to a heat insulating layer covering the outer surface of the end wall of the coil cooling layer.