JPS5820118B2 - ion cassock house - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion accelerator, and is particularly suitable for large current devices.

A conventional accelerator has a plasma source 1 as shown in FIG.
, an extraction electrode 2, an acceleration electrode 3, and a deceleration electrode 4.

When looking at the electrode group 2, 3゜4 from the front, the shape of the opening is similar to that of the second electrode group.
Two types, the porous type shown in Figure A and the multi-pore type shown in Figure B, have been used in the past particularly for large current ion accelerators.

In case B, the ion beam divergence in the slit length direction was extremely small, but the convergence in the width direction (horizontal direction in the figure) was poor.

In the case of the multi-hole type A, since the density temperature of the plasma source is not uniform, the beams emitted from the holes in the center and the holes in the periphery behave differently, worsening the overall convergence. There is a drawback that there is

Therefore, it is necessary to work the electrode with the highest possible precision, and at the same time efforts have been made to obtain a plasma source with good uniformity.

The basic feature of the invention is to arrange the slits as shown in FIG.

With this arrangement, the divergence in the slit length direction, that is, the circumferential direction, is originally small, and the divergence in the width direction, that is, the flat diameter direction, can be converged by giving a curvature to the electrode surface. An ion beam is obtained.

Although FIG. 3 shows a concentric slit arrangement, concentric regular triangles as shown in FIG. 4A or concentric squares as shown in FIG. 4B may be used.

The same thing applies to all concentric regular polygons.

As a plasma source, an axially symmetrical configuration is usually the easiest;
A configuration as shown in FIG. 3 is easy to couple with a plasma source.

In addition, the concentric configuration is easy to manufacture.

When considering application to a neutral particle injection device for nuclear fusion, a vertically elongated beam shape may be required in relation to the particle injection hole shape.

Devices of the type shown in FIG. 2B have conventionally used plasma source electrodes having an aspect ratio of up to 5.

When configuring the present invention using such a plasma source, the electrode opening shape shown in FIG. 5 may be used.

Triangular or pentagonal shapes may be used as long as they are concentric or symmetrical.

Typically, a plasma has a nearly concentric, symmetrical density and temperature distribution within its container.

Therefore, a major feature of the present invention is that the requirements for uniformity of density and temperature of the plasma source are significantly relaxed.

It is well known that a beam can be deflected by giving a curvature to an electrode surface.

(For example, PIasma Physics amd C
controlledNuclear Fusion R
e5earch, 1974 (IAEA, Vienna
t tobe Published).

Paper No., IAEA-CN-33/D
2-2) If the density and temperature distribution of the plasma source are known in advance, the width and curvature of the slit can be set accordingly.

By using the mechanism shown in FIG. 6, the curved surface of the electrode can be freely adjusted, so that accurate correspondence can be obtained to the characteristics of the plasma source.

That is, the electrode portions 6 on both sides of the narrow gap portion 5 are assembled using screws 7.

The screw 7 is cut into the slotted joint 8, (FIG. 3).

The joint part is extremely narrow, and the longitudinal distance that can be adjusted with the screw is small, but a longitudinal movement of about 0 mm is sufficient for fine adjustment to a preset curved surface, so 15C
If you cut a 10mm thread with a diameter of 771, the joint length will be 5 long, which is sufficient.

As shown in FIG. 6B, grooves 9 may be cut in place of screws, and the electrode pieces may be moved in a straight line through a driver.

Furthermore, if the joint portion 10 is made of an insulator, different potentials can be applied to each electrode portion.

This allows more freedom to adapt to variations in plasma source density and temperature.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of an ion accelerator, Fig. 2 is a diagram showing a conventional electrode pattern, Fig. 3 is a diagram showing an electrode pattern according to the present invention, and Fig. 4 is a configuration diagram of regular polygonal concentric slits. , FIG. 5 is a configuration diagram of a general polygonal slit, and FIG. 6 is a diagram showing a fine adjustment mechanism for each electrode piece.

Claims (1)

[Claims] 1. An ion accelerator characterized in that an ion extraction and acceleration/deceleration electrode has an opening formed with a slit, and the slit is arranged concentrically.