JPS5842199A - Neutral particle injection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a neutral particle injection device, and particularly to a neutral particle injection device suitable for use in a plasma confinement type nuclear fusion device.

FIG. 1 shows an outline of a conventional neutral particle injection device.

In the figure, 1 is an ion source that discharges gas and extracts and accelerates the ions being discharged, 2 is an extraction acceleration electrode that selectively extracts only ions from the ion source 1, and 3 is an electrode that neutralizes the charge of the extracted ions. The cell is housed in a vacuum container 4 for a neutral particle injection device. A beam dump 6 and a cryopump 9 for evacuating the interior are housed in the vacuum chamber 4 for the neutral particle injection device, and the cryopump 9 is connected to an external refrigeration facility 10. Vacuum container 4 for neutral particle injection device
The end opposite to the ion source 1 side contains plasma 12 inside.
It is connected to a vacuum vessel 11 for a nuclear fusion device that houses a fusion device. 5 is a gas introduction system that supplies gas from the supply gas source 13 into the neutralization cell 3 via a gas pulse introduction valve, 8 is the trajectory of a fast neutron beam, and 7 is the trajectory of an ion beam that has not undergone charge exchange. .

In such a configuration, the high-speed ion beam extracted from the ion source 1 collides with the gas remaining and floating inside the neutralization cell 3 and becomes a high-speed neutral particle beam that does not lose its charge.
The target plasma 12 is injected, and the plasma 1
2.

By the way, in order to improve the neutralization efficiency within the neutralization cell 3, gas is introduced into the neutralization cell 3 from the supply gas source 13 via the gas introduction system 5, and the high energy from the ion source 1 is −
The ion beam collides with neutral gas to produce a neutral particle beam.

However, normally, the introduced gas is used to maintain the pressure in the neutralization cell 3 at a predetermined value, and in order to obtain a large beam amount, it is necessary to increase the geometric shape of the neutralization cell 3. In this case, the gas flow rate needs to be increased to obtain effective neutralization efficiency. For this reason, the gas load on the exhaust equipment attached to the device increases, making the equipment huge. Furthermore, although the cryopump 9 has conventionally been used for vacuum evacuation, the heat load on the cryopanel also increases and the capacity of the refrigeration equipment becomes enormous.

That is, in order to effectively collide the high-speed ions extracted from the ion source 1 with the residual gas, the neutralization cell 3 needs to maintain a predetermined pressure. Because it often enters the plasma 12, it is necessary to maintain an ultra-high vacuum, which requires an exhaust system with a large exhaust capacity.

The pressure in the neutralization cell 3 is determined by the amount of introduced gas and the above-mentioned pumping speed, but it also depends on the ease with which the gas flows in the neutralization cell 3 (conductance). However, the conductance of this neutralization cell 3 is determined by its geometric shape, which in turn is determined by the ion source 1 and other factors.

Geometry of the neutralization cell to obtain a large ion beam,
In particular, when the diameter is increased, it is necessary to introduce a huge amount of gas in order to obtain the required pressure, and as a result, a huge vacuum evacuation pump is required.

The present invention has been made in view of the above points, and its purpose is to secure the pressure inside the neutralization cell with a small amount of supplied gas, improve the neutralization efficiency of the ion beam, and An object of the present invention is to provide a neutral particle injection device that can reduce the gas load on an exhaust pump.

The present invention achieves the intended purpose by injecting the gas toward the ion source when introducing the gas into the neutralization cell.

The present invention will be described below based on embodiments shown in the drawings. still,
The same reference numerals will be used to explain the same reference numerals as in the prior art.

An embodiment of the present invention is shown in FIGS. 2 and 3.

Since its schematic structure is almost the same as the conventional one, detailed illustrations are omitted here, and only the vicinity of the parts related to the present invention will be shown.

In this embodiment shown in the figure, a nozzle 14f is provided near the beam dump 9 side of the neutralization cell 3 and is inclined toward the ion source 1, and gas from the supply gas source 13 is introduced into this nozzle 14. A system 5 is connected to inject gas into the neutralization cell 3 through a nozzle 14.

In this embodiment configured in this manner, the gas injected from the nozzle 14 forms a gas flow in the direction of the ion source 1 up to the degree of mean freedom, and then flows toward the inner wall of the neutralization cell 3 and between the gas particles. After repeated collisions with ion beams, etc.
The direction of movement of gas particles is diffused compared to uniform force, and they come out to the exhaust pump side. In this case, since a flow that inhibits gas diffusion occurs at the end of the neutralization cell 3, it is possible to increase the pressure inside the neutralization cell 3 without particularly increasing the amount of gas supplied, and the ion beam It is possible to increase the carbonation efficiency of Furthermore, since the amount of gas to be supplied is not large, there is no need to increase the size of a cryopump or the like for evacuation. In other words, the gas load on the vacuum pump can be reduced.

Furthermore, even higher effects can be expected by making the diameter of the nozzle 14 as narrow as possible and increasing the directivity of the gas flow. Note that the energy of the ion beam A+ is normally several tens of keV, whereas the energy of the injected gas B is about the energy of thermal motion, so even if the gas flow is in the opposite direction to the ion beam, the energy of the neutral particle beam A is reduced. There is nothing to do and no problem.

According to the above-described neutral particle injection device of the present invention, the neutral particle injection device is provided in the middle of the trajectory of ions extracted from the ion source which discharges gas and extracts and accelerates the ions being discharged via the extraction acceleration electrode. Since gas is introduced from the outside by the gas supply means into the neutralization cell for neutralizing charges, toward the ion source side, the inner end of the neutralization cell This creates a flow that inhibits gas diffusion, making it possible to increase the pressure inside the neutralization cell without particularly increasing the amount of gas supplied, which of course increases the neutralization efficiency of the ion beam. Since the amount of gas to be supplied is not large, there is no need to increase the size of the evacuation tank, etc., and the gas load on the evacuation pump can be reduced, making it very effective when used in this type of device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional neutral particle injection device, FIG. 2 is a schematic configuration diagram of a neutral particle injection device showing an embodiment of the present invention, and FIG. 3 is a diagram showing a configuration in which the nozzle in FIG. FIG. 2 is a sectional view of a neutralization cell near the DESCRIPTION OF SYMBOLS 1... Ion source, 2... Extraction acceleration electrode, 3... Neutralization cell, 4... Vacuum container for neutral particle injection device, 5...
... Gas introduction system, 6... Beam dump, 7... Ion trajectory, 8... Neutral particle trajectory, 9... Cryopump, 10... Refrigeration equipment, 11... Nuclear fusion device main body,
12...Plasma, 71 Figure 3 Broom 2 Figure 3 Figure/3

Claims (1)

[Scope of Claims] 1. An ion source that discharges gas and extracts and accelerates ions in the discharge, and an ion source that is provided on the trajectory of the ions extracted from the ion source via an extraction accelerating electrode and that reduces the charge of the ions. A neutralization cell for neutralizing, a vacuum tube that guides the neutral particles neutralized in the neutralization cell to an incident device, and a gas that introduces a gas from the outside into the neutralization cell. A neutral particle injection device comprising a supply means, characterized in that the neutralization cell is configured to direct the introduction of gas from the gas supply means into the neutralization cell in the direction of the ion source. Neutral particle injection device. 2. The neutralization cell is provided with a nozzle inclined toward the ion source near the beam dump side provided in the vacuum chamber, and gas is introduced from the gas supply means through the nozzle. A neutral particle injection device according to claim 1, characterized in that the neutral particle injection device is configured as follows. 3. The gas supply means includes a gas source, a gas pulse introduction valve that introduces gas from the gas source, and a gas introduction part that has one end connected to the gas pulse introduction valve and the other end communicated with the neutralization cell. A neutral particle injection device according to claim 1 or 2, characterized by comprising: