JPH058652Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vacuum leak prevention structure for a bending electromagnet vacuum box, which is suitable for vacuum sealing of a wide area magnetic analysis electromagnet vacuum box.

Motion analysis of charged particle beams from accelerators or charged particles generated by nuclear reactions is performed using electromagnets. This motion analysis not only requires high resolution, but also measures particles with different momentums simultaneously, or measures particles with as wide a range of momentums as possible simultaneously, or measures particles with as wide a range of momentums as possible at once. Although analysis is required, various wide-area magnetic analyzers have been considered so far.

FIGS. 1 and 2 are diagrams showing an example of a wide area magnetic analyzer. In the example of the magnetic analyzer in Figure 1,
Particles that do not have an electric charge among the particles that enter through the entrance 5 travel straight even in the magnetic field, and exit from the electromagnet through the exit 6. On the other hand, a charged particle beam is deflected in a certain direction by a force in a magnetic field. In the same magnetic field, particles with large momentum have a large deflection radius and move in direction C or B, but particles with small momentum have a small deflection radius and bend in direction A. Particles bent by the magnetic field of the electromagnet move into a vacuum box. It exits from the vacuum box 4 through a window 8 covered with Mylar film and is captured by an analyzer. In addition, 1 is a magnetic pole part in a vacuum box, 2 is a coil of an electromagnet, 3 is a yoke of an electromagnet, 4 is a vacuum box, and 7 is a base.

In this case, the inside of the vacuum box of the wide area magnetic analysis electromagnet needs to be maintained at a high vacuum to allow the particles to pass through, and it is preferable to cover the magnetic pole part where the particles travel with the vacuum box. In terms of structure, it is necessary to widen the electrode space created by the electromagnet, and in order to secure the required magnetic field strength in the electrode space, the electromagnet has to be large and expensive.

For this reason, the magnetic pole of the electromagnet is constructed to be directly exposed inside the vacuum box, and an O-ring is used at the joint between the magnetic pole and the vacuum box to seal the vacuum.

However, this vacuum seal part is the most susceptible to mechanical distortion each time the inside of the vacuum box is evacuated or filled with air, and when the inside of the vacuum box is evacuated to a vacuum, the vacuum box dents in the center, so the vacuum Vacuum leaks often occur around the pole portions that are fitted with O-rings for sealing.

In view of this point, the main object of the present invention is to propose a vacuum leak prevention structure that is provided with a structure to avoid vacuum leaks in the O-ring vacuum seal between the electrode and the vacuum box.

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

FIG. 4 is a diagram showing an example of the present invention. This figure 4 is an enlarged view of part B in figure 3.
It is a sectional view of A and A in the figure.

11 indicates the side plate of the vacuum box 4 at the magnetic pole end portion;
It is sealed with the magnetic pole 10 using an O-ring 12.

When the inside of the vacuum box 4 is evacuated and pressure is applied to the lower plate 13 and pushed up, the side plate 11 is also pushed down, and if the tightness becomes larger than the sealing margin of the O-ring 12, vacuum leakage may occur. be. Therefore, a support plate 14 is separately connected to the side plate 11 of the vacuum box 4 by welding so as to be supported on the outside of the coil 2. In this case, since the structure is such that the movable plate 15 and the L-shaped stopper 19 for hanging the block can be removed from the yoke, the coil 2 can be disassembled independently.

On the other hand, another movable plate 15 is fixed to the yoke by a second fixing bolt 18 from an angle 19 so that the support plate 14 connected to the O-ring seal of the vacuum box 4 can be lifted and adjusted to keep the tightening margin constant. ,
The structure is such that the side plate 11 with an O-ring is lifted up via a movable plate 15 and a support plate 14.

In this case, the protrusion 16 installed on the movable plate 15
is designed to be tightly inserted into the hole of the support plate 14, and the structure is such that vacuum leakage does not occur due to displacement due to play in the screw hole, etc. Further, in order to efficiently move the support plate 14 and the movable plate 15, they are integrated by a first fixing bolt 17.

With this structure, after incorporating the vacuum box as an electromagnetic device, by adjusting the tightening of the L-angle bolt 18, the tightness of the O-ring 12 can be adjusted while preventing vacuum leakage due to vacuum stress distortion. There is.

As described above, according to the present invention, in a structure in which the magnetic pole of the electromagnet of the bending electromagnet vacuum box also serves as the upper and lower cover plates of the vacuum box, the side plate that supports the O-ring that makes the space between the vacuum box and the magnetic pole airtight is supported. The structure is suspended by a plate, and the supporting plate is movable by a screw provided on the outer surface of the vacuum box, and the airtightness between the electromagnet, magnetic pole, and vacuum box after the electromagnet is assembled is adjusted by the screw. As a result, the drawbacks of the conventional vacuum box for wide area magnetic analysis electromagnets and the vacuum seal between the magnetic poles can be eliminated, and the vacuum box according to the present invention is industrially useful.

[Brief explanation of the drawing]

Figures 1 and 2 are a plan view and side view showing an example of a vacuum box for wide area magnetic analysis electromagnet, Figure 3 is a sectional view taken along line A-A in Figure 1, and Figure 4 is an example of the present invention. FIG. 2...Electromagnetic coil, 4...Vacuum box, 11...
...Side plate, 12...O ring, 13...Lower plate, 14
... Support plate, 15 ... Movable plate, 17, 18 ... Bolt, 19 ... L-shaped stopper.

Claims (1)

[Scope of utility model registration request] In a structure in which the magnetic poles of the electromagnet of the deflection electromagnet vacuum box also serve as the upper and lower lid plates of the vacuum box, the side plate that supports the O-ring that makes the space between the vacuum box and the magnetic pole airtight is suspended by the support plate, and the side plate is suspended by the support plate. The plate is movable by screws provided on the outside of the vacuum box,
A vacuum leak prevention structure characterized in that the airtightness between the electromagnet, the magnetic pole and the vacuum box after the electromagnet is assembled is adjusted by the screw.