JPH0935895A - Plasma generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate lighting an arc utilized for generating plasma. SOLUTION: In a duo-plasma type ion source, an arc discharge from a thermion emitting filament is utilized in a plasma generating process. A member having an edge, a bead 11 with edge is fitted to the filament 1. This bead is formed of high melting point metal material of tantalum or molybdenum and the like, to intensify an electric field of an edge 11b in a circumferential part, with a discharge from the edge serving as a trigger of an arc, to improve an arc lighting property. A wire and a thin band by the high melting point metal material may be wound to the filament. An end part and a cut section of the wire and the thin band are formed to serve as the edge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generator such as an ion source which utilizes arc discharge from a thermoelectron emission filament in a plasma generating process, and more particularly to a plasma generator capable of easily lighting an arc.

[0002]

2. Description of the Related Art FIG. 3 is a basic structural diagram of a plasma generation device, for example, a duoplasma type ion source, which utilizes arc discharge of a filament portion in a plasma generation process. The ion source typically has a cathode with a filament 1, an intermediate electrode 2 and an anode 3. An arc power supply 4 is connected between the cathode filament 1 and the anode 3, and the intermediate electrode 2 is connected to the arc power supply via a resistor 5. When an ion source gas is introduced into the intermediate electrode 2 and an arc voltage is applied between the anode 3 and the filament 1 of the cathode, arc discharge is generated, and thermoelectrons emitted from the filament generate plasma along the discharge path. Occurs. The intermediate electrode and the anode are made of a magnetic material to form a magnetic pole, and the plasma is magnetically compressed by the magnetic field between the intermediate electrode and the anode to generate high-density plasma.

[0003]

At the time of starting the ion source, it is sometimes difficult to turn on the arc, and in order to wait for a long time (up to 1 hour) to turn on or to facilitate the arc lighting. In addition, as the arc power source 4, a higher voltage (for example, 500 V for a normal operating voltage of 200 V) is used.
There was a problem that the one of V) had to be used.

The present invention relates to a plasma generating apparatus such as an ion source which facilitates lighting of an arc used for generating plasma.

[0005]

SUMMARY OF THE INVENTION The present invention is a plasma generator that utilizes arc discharge from a thermionic emission filament in the plasma generation process, wherein a member having an edge is attached to the filament. To do.

[0006]

Since a member having an edge is attached to the thermionic emission filament, the electric field becomes strong at the edge portion of the member, the discharge from the edge triggers the arc, and the arc is easily turned on.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an essential part of the embodiment, (a) is a configuration diagram in which a member having an edge is attached to a thermoelectron emission filament, and (b) is a plan view of the member having an edge,
(C) is sectional drawing in the AA line of (b). A member having an edge and a bead 11 with an edge are fitted to the thermionic emission filament 1. The bead has a hole 11a through which the filament 1 passes through in the center, an edge 11b with a sharp circumference, and is made of a high melting point metal material such as tantalum or molybdenum. By fitting and attaching the bead 11 with the edge to the filament 1, the electric field at the portion of the edge 11b becomes strong, the discharge from the edge triggers the arc, and the arc is easily turned on.

FIG. 2 is a block diagram of the essential part of another embodiment. In FIG. 2A, a member 21 having an edge is attached by winding a wire around the thermoelectron emission filament 1. The end of the wire wound around the filament and the cut end serve as an edge forming a strong electric field, and the arc is triggered by forming the strong electric field. The wire is also made of a high melting point metal such as tantalum or molybdenum.

In FIG. 2 (b), the filament 1 is attached with a member bon 31 having an edge by winding a thin strip formed of a refractory metal material such as tantalum or molybdenum, and an end portion of the strip. , The edge becomes the edge that forms a strong electric field. Members 21, 3 with such edges
1 is about 1 or 2 in the thermionic emission filament,
Install as appropriate.

[0010]

Since the present invention is configured as described above, the electric field at the edge of the member having the edge attached to the thermionic emission filament becomes strong, so that the discharge from the edge triggers the arc, The lighting performance of is improved. Therefore, the waiting time for lighting can be shortened, and the arc power supply need only have a low voltage.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of another embodiment.

FIG. 3 is a basic structural diagram of a duoplasma type ion source.

[Explanation of symbols]

 1 Thermionic emission filaments 11, 21, 31 Members with edges

Claims (1)

[Claims] 1. A plasma generator that utilizes arc discharge from a thermoelectron emission filament in a plasma generation process, wherein a member having an edge is attached to the filament.