JPS6355757B2 - - Google Patents

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 to extract and accelerate ions in the discharge, and 2 is an ion source 1.
Extraction acceleration electrode that selectively extracts only ions,
Reference numeral 3 denotes a cell for neutralizing the charges of extracted ions, which is housed in a vacuum container 4 for a neutral particle injection device.
Inside the vacuum chamber 4 for the neutral particle injection device, there is a beam dump 6 and a cryopump 9 that evacuates the inside.
The cryopump 9 is connected to external refrigeration equipment 10. The end of the vacuum vessel 4 for a neutral particle injection device on the side opposite to the ion source 1 side is connected to a vacuum vessel 11 for a nuclear fusion device that houses a plasma 12 therein. 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 a trajectory of a fast neutron beam; and 7 is a trajectory of an ion beam without charge exchange. .

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

By the way, in order to improve the neutralization efficiency within the neutralization cell 3, the gas introduction system 5 is connected to the supply gas source 13.
A gas is introduced into the neutralization cell 3 through the ion source 1, and the high-energy ion beam from the ion source 1 collides with the neutral gas to obtain 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 a 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 of gas flow (conductance) in the neutralization cell 3. but,
The conductance of this neutralization cell 3 is determined by its geometrical shape, and the geometrical shape is also determined by the ion source 1 and other factors.

In order to obtain a large ion beam, increasing the geometry of the neutralization cell, especially the diameter, requires a huge amount of gas to be introduced to obtain the required pressure, and as a result, a huge vacuum pump is required. This ends up being the case.

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. Note that the same reference numerals will be used to explain the same reference numerals as those in the prior art.

An embodiment of the present invention is shown in FIGS. 2 and 3.
Since its schematic configuration 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 14 that is inclined toward the ion source 1 is provided near the beam dump 9 side of the neutralization cell 3, 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 way, the nozzle 1
The gas injected from 4 forms a gas flow in one direction of the ion source up to the degree of mean freedom, and then
After repeated collisions with the inner wall of the neutralization cell 3, gas particles, ion beams, etc., the direction of movement of the gas particles becomes isotropic, diffuses, and emerges toward the exhaust pump. 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, nozzle 1
Even higher effects can be expected by making the diameter of No. 4 as thin as possible and increasing the directivity of the gas flow. Note that the energy of the ion beam A ⁺ is usually 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 ^* will be reduced. There is nothing to do and no problem.

According to the neutral particle injection device of the present invention described above, the neutral particle injection device is provided in the middle of the trajectory of ions extracted via the extraction acceleration electrode from the ion source that discharges gas and extracts and accelerates the ions being discharged. Since gas is introduced from the outside by the gas supply means into the neutralization cell to neutralize the electric charge, 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 equipment for evacuation, 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 shown in FIG. It is a sectional view of a neutralization cell in the vicinity of 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 orbit, 8 ... Neutral particle trajectory, 9 ... Cryopump, 10 ... Refrigeration equipment, 11 ... Nuclear fusion device main body, 12 ... Plasma, 13 ... Gas source, 14 ... Nozzle.

Claims (1)

[Scope of Claims] 1. An ion source that discharges a gas and extracts and accelerates the ions being discharged, 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 neutralizes the electric charge of the ions. A neutralization cell for sexualization,
A neutral particle injection device comprising: a vacuum tube that guides the neutral particles neutralized in the neutralization cell to the injection target device; and a gas supply means that introduces gas from the outside into the neutralization cell. , the neutralization cell introduces gas from the gas supply means into its interior,
A neutral particle injection device characterized in that the neutral particle injection device is oriented in the direction of the ion source. 2. The neutralization cell is provided with a nozzle that is 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: 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 whose one end is connected to the gas pulse introduction valve and whose other end is in communication with the neutralization cell. A neutral particle injection device according to claim 1 or 2, characterized in that it is comprised of: