JPH0552999A - Electric charge converter - Google Patents

Abstract

PURPOSE:To prevent choking of an ion beam path hole and reduce consumption of metal in a metal pot. CONSTITUTION:After heating Li 4 with a heater 3 to appropriate temperature and filling a metal vapour chamber 5 with Li vapour, an ion beam 8 is passed and then a positive ion beam 8 is converted to a negative ion beam to be output. At this moment, the diffused Li vapour attaches on the inner surface of an aperture 10 as liquid, flows in a groove 11 to wires 12 and returns to a metal pot 2. Also, the Li liquid attaching at the inlet and outlet for ion beam on cell 1 also returns to the metal pot by way of the wires 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for converting the charge of an ion beam, and more particularly to a charge conversion device installed before a tandem type electrostatic accelerator.

[0002]

2. Description of the Related Art When obtaining a He ⁺ or He 2 ⁺ beam of about several MeV, for example, when obtaining an ion beam for an analyzer (RBS or PIXE analyzer, etc.) that uses a high-energy ion beam, it is compact. The tandem electrostatic accelerator is often used because it is easy to handle. The operation principle of the tandem type electrostatic accelerator is that negative ions such as He ⁻ are received from one entrance, and He ⁺ or He ²⁺
Since two-stage acceleration is performed by converting into positive ions such as, a negative ion source is required in the preceding stage.

As the negative ion source, a charge conversion device using alkali metal vapor is used. In this charge conversion device, as shown in the following reaction formula, positive ions such as He ⁺ are passed through the vapor of an alkali metal such as Li, and electrons are given from the alkali metal vapor to the positive ions, so that the positive ions are neutralized. And negative ions. He ⁺ + Li → He + Li ⁺ He + Li → He ⁻ + Li ⁺ A conventional structure of such a charge conversion device is shown in FIG. 3. In FIG. 3, a cylindrical housing 9 whose inside is kept vacuum, and a cell 1 provided in the center of the inside of the housing 9 constitute a charge conversion device, and an alkali metal such as Li is provided under the cell 1. A metal reservoir 2 for housing is provided, and a heater (cartridge heater) 3 is inserted into the metal reservoir 2 from above. A space (metal vapor chamber) 5 in which vapor of metal vaporized by being heated and melted by the heater 3 stays is provided above the metal reservoir 2, and the ion beam passes through the cell walls on both sides of the space. A small hole 6 is provided for this purpose. The ion beam passage hole 6 is formed to be elongated and tapered so that the outer side is narrower in order to minimize leakage of metal vapor to the outside of the cell.

A window 7 for passing an ion beam is also provided on both sides of the housing 9. In the cell 1, the central axis of the ion beam passage hole 6 is the central axis of the ion beam passage window 7 of the housing 9. Housing 9 so that it is coaxial
Retained within. The positive ion beam 8 passing through the ion beam passage window 7 and the ion beam passage hole 6 collides with the alkali metal vapor in the metal vapor chamber 5, and is converted into negative ions by the above-mentioned electron transfer reaction and the ions on the opposite side are collided. It is supplied from the beam passage window 7 to a tandem electrostatic accelerator or the like.

[0005]

The conventional charge conversion device is constructed as described above, and the alkali metal 4 is heated by the heater 3 in the metal reservoir 2 and evaporated to stay in the metal vapor chamber 5. However, since the temperature of the wall of the cell 1 is lower than the melting point of the metal, the metal vapor gradually deposits on the wall of the cell 1 as a solid. In particular, the ion beam passage hole 6 is made small in order to minimize the leakage of vapor, so that the solid metal is likely to be clogged due to the precipitation. Ion beam passage hole 6
When the clogged up, the cell 1 was conventionally taken out and removed from the charge conversion device. In this case, however, the vacuum of the charge conversion device must be broken once and vacuumed again.
There was a problem that it took a lot of time and effort.

Further, it is difficult to control the temperature of the heater 3 for heating the alkali metal of the metal reservoir 2, and if care is not taken,
The evaporated metal may leak from the ion beam passage hole 6 rapidly, and the metal may be rapidly consumed so that negative ions cannot be obtained.

The present invention was devised to solve the above-mentioned problems, and can prevent clogging of the ion beam passage hole and reduce the consumption of metal in the metal reservoir. An object is to provide a charge conversion device.

[0008]

In order to achieve the above object, the charge conversion device of the present invention has an ion beam passage hole provided with an aperture having a groove extending from the inner circumference to the outer circumference thereof, and at the entrance / exit. And a guide member for returning the liquid metal to the metal reservoir along the inner surface of the cell.

[0009]

The charge conversion device of the present invention is configured as described above, and the ion beam entrance and exit of the cell and the aperture are
The liquid metal adheres due to the surface tension, but the liquid metal adhered to the aperture is transmitted to the guide member through the groove cut in the aperture and returns to the metal reservoir together with the liquid metal adhered to the ion beam entrance / exit. The holes are not clogged, the metal consumption in the metal reservoir is reduced, and the life of the cell can be significantly extended.

[0010]

FIG. 1 shows a charge conversion device according to an embodiment of the present invention.
2 will be described. The basic structure of this embodiment is the same as that of the conventional charge conversion device shown in FIG. 3, and only the differences from the conventional charge conversion device will be described. As shown in FIG. 1, the aperture 1 is formed in the ion beam passage holes 6, 6 of the cell 1.
0 and 10 are attached, and a cover 13 is attached to the top of the metal reservoir 2. Also, wire 1
2, 12 are stretched from the beam entrance / exit of the cell 1 along the inner surface of the cell, and the other ends of the wires 12, 12 are hung from above the cover 13 toward the metal reservoir 2.

FIG. 2 is an enlarged view of the metal reservoir 2 and the ion beam passage hole 6 of the cell. The aperture 10 attached to the ion beam passage hole 6 of the cell 1 has a groove 11 extending from the inner circumference to the outer circumference thereof. Has been cut. A cover 13 is attached to the uppermost portion of the metal reservoir 2, and the wire 12 stretched from the ion beam entrance / exit of the cell 1 along the inner surface of the cell 12.
The other end of is hung from the top of the cover 13 toward the metal reservoir 2.

The operation of the charge conversion device of this embodiment having such a structure will be described below. Li in the metal reservoir 2 of the cell 1
After inserting 4, the cell 1 is housed in the housing 9. Then, the heater 3 heats the Li 4 to an appropriate temperature to fill the metal vapor chamber 5 with the Li vapor. Then, the ion beam 8 is passed through the ion beam passage window 7 and the ion passage hole 6.
When passing through, the positive ion beam 8 collides with Li vapor in the metal vapor chamber 5, is converted into negative ions by the electron transfer reaction, and is supplied from the ion beam passage window 7 on the opposite side to the tandem electrostatic accelerator or the like. It

At this time, Li filled in the metal vapor chamber 5
The vapor diffuses through the ion beam passage holes 6, 6 of the cell 1, but most of the vapor adheres to the inner circumference of the apertures 10, 10 as a liquid. If the aperture does not have a slit, the surface tension may cause a film to adhere to the through hole of the aperture to block the beam. However, if there is a slit, the Li liquid adhering to the aperture 10 or 10 may cause the Li liquid to adhere to the aperture 10 or 10. Wire 1 through the grooves 11, 11 of
It is transmitted to 2 and 12, and returns to the metal reservoir 2. Further, the Li liquid that has passed through the apertures 10 and 10 and attached to the ion beam entrance / exit of the cell 1 travels through the wire 12 and returns to the metal reservoir 2.

It should be noted that the cover 13 prevents the liquid Li bumped in the metal reservoir 2 from directly adhering to the apertures 10, 10.

In the above embodiment, the cover 13 is attached to the uppermost part of the metal reservoir 2, but it is not particularly necessary when the amount of metal to be put in the metal reservoir is small or when the metal having a low possibility of bumping is used. .. Further, in the above embodiment, the case where the wire 12 is provided up to the ion beam entrance / exit of the cell 1 has been described. However, even if the length of the wire 12 reaches the groove 11 of the aperture 10 from the metal in the metal reservoir, a sufficient effect is obtained. Can be obtained.

[0016]

The charge conversion device of the present invention is configured as described above, and the metal vapor diffused from the metal vapor chamber adheres to the inner circumference of the aperture as a liquid and diffuses from the inlet / outlet of the cell. Since the amount of metal vapor to be used is reduced, the consumption of metal can be reduced. In addition, the liquid metal attached to the cell inlet / outlet travels through the wire, and the metal liquid attached to the aperture is transmitted to the wire through the groove of the aperture, and eventually returns to the metal reservoir, which effectively prevents the cell inlet / outlet and aperture from being clogged. Therefore, the life of the cell can be significantly extended.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a charge conversion device of the present invention.

FIG. 2 is an enlarged view of a metal reservoir and an ion beam passage hole of the charge conversion device of FIG.

FIG. 3 is a diagram showing a conventional charge conversion device.

[Explanation of symbols]

1 ... cell 2 ... metal reservoir 3 ... heater 4 ... Li (liquid metal) 6 ... beam passing hole 10 ... aperture 11 ... groove 12 ... wire 13 ... cover

Claims (1)

[Claims] 1. A charge conversion device comprising a metal reservoir, a metal vapor chamber provided above the metal reservoir, and a cell having an ion beam passage hole formed on both sides of the metal vapor chamber,
The ion beam passage hole, characterized in that it has an aperture having a groove cut from the inner circumference to the outer circumference, and a guide member for returning the metal liquid transmitted through the groove to the metal reservoir. Charge conversion device.