JPH10255726A - Surface wave plasma emission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of the reflected wave in a discharge container and enable the high density and uniform plasma to be generated efficiently. SOLUTION: At the end section of a discharge tube 10 having a cavity section 10A, a wave guide tube 2 giving a micro wave and a micro wave cavity wall 5 and the like are provided, in a emission device connecting a surface wave by a micro wave from a surface wave connecting section 7 to the discharge tube 10, a lead wire 12 is arranged along the longitudinal direction of the discharge tube 10 in the said discharge cavity section 10A, a magnetic field perpendicular to the electrical field of the surface wave is given by feeding the prescribed current to this lead wire 12 from the direct power source. Since the electron in a plasma P causes the cyclotron resonance and absorbs the surface wave energy, a reflected wave of the surface wave is reduced and the plasma with high density and uniformity is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface wave plasma light emitting device which is used as a light source and a plasma source for a process and gives a surface wave to a discharge vessel to generate high density plasma.

[0002]

2. Description of the Related Art A surface wave plasma light emitting device excites a discharge material in a discharge vessel by a surface wave to generate high density plasma to emit light. It is used as a process plasma source and the like.

FIG. 4 shows the configuration of a conventional surface wave plasma light emitting device. As shown in FIG. 4, in this device, a guide is provided at an end of a discharge tube 1 containing a discharge material (gas). The waveguide 2 is coupled, and a magnetron 3 for generating a microwave is connected to the waveguide 2. A microwave cavity wall 5 for forming a microwave cavity 4 on the outer periphery of the discharge tube 1 is provided on the upper side of the drawing of the coupling portion of the waveguide 2 with the discharge tube 1.
Is arranged.

Further, a center conductor 6 is provided on the outer periphery of the discharge tube 1 at the joint portion, which is located close to the rear end, and the outer diameter of the center conductor 6 becomes smaller as it goes toward the center of the discharge tube 1 ( (Conical shape). By providing a predetermined space between the thin end portion (right side) of the center conductor 6 and the microwave cavity wall 5, the surface wave (microwave) coupling portion 7 is formed.

According to the above configuration, when the microwave (energy) oscillated by the magnetron 3 is supplied to the outer peripheral portion of the central conductor 6 and the microwave cavity 4 via the waveguide 2, the central conductor A surface wave is coupled to the discharge tube 1 from a surface wave coupling portion 7 between the microwave cavity wall 6 and the microwave cavity wall 5. That is, in the surface wave coupling section 7, the discharge material in the discharge tube 1 is excited by the surface wave, and the plasma P is generated on the inner wall side of the discharge tube 1. Then, the surface wave propagates along the longitudinal direction (plasma interface) of the discharge tube 1 while generating the illustrated plasma P, whereby plasma emission is performed in the discharge tube 1.

[0006]

However, in the above-mentioned conventional surface wave plasma light emitting device, the surface wave propagating in the discharge tube 1 is reflected at the tip (right side in the figure) of the discharge tube 1, and the reflected wave There is a problem that the plasma distribution becomes uneven due to the influence. In other words, the energy of the surface wave is absorbed by the plasma during propagation and attenuated, but a reflected wave is formed by the surface wave that reaches the tip of the discharge tube 1 without being absorbed, and a standing wave is formed by the reflected wave. Therefore, a non-uniform plasma is generated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to suppress the generation of reflected waves in a discharge vessel and efficiently generate high-density and uniform plasma. An object of the present invention is to provide a surface wave plasma light emitting device.

[0008]

According to a first aspect of the present invention, there is provided a surface acoustic wave plasma light emitting device comprising: a discharge vessel containing a discharge material; a microwave generating means; A microwave coupling means for coupling the microwave generated by the means to the discharge vessel as a surface wave, and a magnetic field generating means for forming a magnetic field inside the discharge vessel; The luminous efficiency is enhanced by coupling with a magnetic field generated by the magnetic field generating means. The invention according to a second aspect is characterized in that the discharge vessel is formed in a hollow shape, and a magnetic field generating means having a conducting wire disposed in the hollow portion is provided, and a surface wave coupled to the discharge vessel is orthogonal to an electric field thereof. It is characterized in that a magnetic field is applied.

According to the above configuration, for example, a conducting wire can be arranged in the hollow portion of a hollow discharge vessel to generate a magnetic field orthogonal to the electric field of the surface wave. Then, the electrons in the plasma perform cyclotron motion around the lines of magnetic force and are accelerated by the electric field of the surface wave, so that the energy is increased. These high-energy electrons collide with the discharge material and generate a high-density plasma,
Therefore, the surface wave energy is efficiently absorbed by the high-density plasma. As a result, the arrival ratio of the surface wave to the tip of the discharge vessel or the like is greatly reduced, and the generation of the reflected wave is suppressed.

[0010]

1 and 2 show the configuration of a surface wave plasma light emitting device which is an example of an embodiment of the present invention. In FIG. 1, a discharge tube 10 is a cylindrical tube having a hollow portion 10A, in which a discharge material such as a mixed gas of a rare gas and a halogen gas is sealed. At the end of the discharge tube 10, the waveguide 2
A magnetron 3 for generating, for example, a microwave of 2.45 GHz is connected through a microwave cavity, and a microwave cavity for forming a microwave cavity 4 is formed on the outer periphery of the discharge tube 10 at the coupling portion with the waveguide 2. A wall 5 is provided.

At the joint between the discharge tube 10, the waveguide 2, and the microwave cavity wall 5, a conical center conductor 6 is provided on the outer periphery of the discharge tube 10, and the center conductor 6 is thin. The end is arranged toward the center of the discharge tube 10. Then, by providing a predetermined interval between the thin end portion of the center conductor 6 and the microwave cavity wall 5, the surface wave coupling portion 7 is formed. Therefore, the waveguide, the microwave cavity wall 5 and the center conductor 6 are arranged as microwave coupling means.

The hollow portion 10A of the discharge tube 10
A DC power supply 14 is connected to the conductive wire 12 along the longitudinal direction thereof, and the conductive wire 12 and the DC power supply 14 are arranged as magnetic field generating means.

This example has the above configuration, and the microwave (energy) oscillated by the magnetron 4 is:
When supplied to the microwave cavity 4 via the waveguide 2 and a surface wave by the microwave is given to the discharge tube 10 from the surface wave coupling portion 7, the discharge material is excited in the discharge tube 10,
A plasma P is generated. Further, the surface wave propagates along the interface between the discharge tube 10 and the plasma P in the longitudinal direction (horizontal direction) of the discharge tube 10.

Here, as shown in FIG. 1, the electric field E of the surface wave has its components only in the axial direction and the radial direction of the discharge tube 10. On the other hand, the DC power supply 1
4, a magnetic field F orthogonal to the electric field E can be generated as shown in FIG. Then, for example, the intensity of 875 Gauss (Gauss
In the case of the magnetic field F of (1), the electrons in the plasma P cause cyclotron resonance and absorb energy from the electric field to become high energy.

The high-energy electrons collide with the discharge material in the discharge tube 10 to increase the density of the plasma P. Accordingly, the surface wave energy is efficiently absorbed by the plasma P, and the ratio of the surface wave reaching the tip of the discharge tube 10 (the right end in the figure) is reduced as compared with the conventional case, and the generation of the reflected wave is reduced. Is suppressed. As a result, the plasma distribution becomes uniform.

FIG. 3 shows a change in light emission output with respect to microwave power using the magnetic field strength as a parameter.
This graph shows that the microwave frequency of the above device was 2.45.
GHz, and a comparison was made between when a magnetic field strength of 875 Gauss was applied and when no magnetic field was applied. As shown in the figure, the emission output when applying a magnetic field of 875 Gauss is
It can be seen that it is 1.5 times as large as when there is no magnetic field (0 Gauss).

The discharge tube 10 has a hollow portion 10.
When the plasma P is generated to the vicinity of A, the surface wave may propagate to the hollow portion 10A. Therefore, it is necessary to set the outer diameter of the discharge tube 10 to be sufficiently large with respect to the microwave power.

Further, the magnetic field generating means and the discharge vessel of the present invention apply a magnetic field in a direction intersecting the electric field of the surface wave,
Any configuration may be used as long as it can generate cyclotron resonance, and the magnetic field generating means is not limited to a hollow one, such as a coil or a permanent magnet having an appropriate shape, and may be a cylindrical or rectangular parallelepiped.

[0019]

As described above, according to the first aspect of the present invention, there is provided a surface wave plasma light emitting device for coupling a surface wave to a discharge vessel by using a microwave to form a magnetic field inside the discharge vessel. Since the surface wave is combined with the magnetic field to enhance the luminous efficiency, the generation of the reflected wave in the discharge vessel can be suppressed, and a high-density and uniform plasma can be formed. .

According to the second aspect of the present invention, a conducting wire is arranged in the hollow portion of the discharge vessel formed in a hollow shape, and a magnetic field orthogonal to the electric field of the surface wave is applied.
There is an advantage that high-density plasma can be efficiently generated.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a configuration of a surface acoustic wave plasma light emitting device according to an embodiment of the present invention.

FIG. 2 is a view of the light emitting device of FIG. 1 as viewed from a front end side.

FIG. 3 is a graph showing a change in light emission output with respect to microwave power measured by the light emitting device of the embodiment.

FIG. 4 is a partial cross-sectional view showing a configuration of a conventional surface wave plasma light emitting device.

[Explanation of symbols]

 1, 10: discharge tube, 2: waveguide, 4: microwave cavity, 7: surface wave coupling part, 10A: hollow part, 12: conducting wire, 14: DC power supply, P: plasma, E: electric field, F … Magnetic field.

Claims (2)

[Claims] A discharge vessel containing a discharge material; microwave generation means; microwave coupling means for coupling the microwave generated by the microwave generation means to the discharge vessel as a surface wave; And a magnetic field generating means for forming a magnetic field, wherein the surface wave supplied by the micro-coupling means is combined with a magnetic field generated by the magnetic field generating means to enhance luminous efficiency. 2. The apparatus according to claim 2, wherein the discharge vessel is formed in a hollow shape, and a magnetic field generating means is provided in which a conductive wire is disposed in the hollow portion.
The first aspect, wherein a magnetic field orthogonal to the electric field is applied to the surface wave coupled to the discharge vessel.
The surface wave plasma light emitting device according to claim.