JP2745336B2 - Microwave induction plasma igniter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a discharge tube for flowing a plasma gas.
Microwave Induced Plasma (Microwave In)
More particularly, the present invention relates to a microwave-induced plasma ignition device that does not generate noise and does not require a high voltage generator.

<Conventional Technology> Hereinafter, a description of a conventional technology will be described with reference to the drawings.

FIG. 2 is a diagram provided for explanation of a conventional technique.
FIG. 1A is a schematic diagram illustrating the configuration, and FIGS. 2B and 2C are diagrams for explanation of FIG. 1A.

2 (A) to 2 (C), a plasma gas (hereinafter abbreviated as "PLG") 2 such as helium or argon is led to a discharge tube 1 made of, for example, quartz.
The cavity 5 into which the μ-wave 4 is injected from the side is, for example, when the μ-wave is at 2.45 GHz, it is a cavity resonator of this μ-wave, and a hole is formed in the center through the discharge tube 1. The microwaves resonate in the cavity and the energy is collected at the center.

In such a combination, PLG2
Flowing, a plasma (hereinafter abbreviated as “PL”) 3 stands in the discharge tube due to the μ-wave energy collected at the center inside the cavity. When fine particles enter the plasma, a phenomenon of gasification → ionization → emission occurs. The spectrum of this "emission" is detected by the analysis means 6 and the fine particles are analyzed.

By the way, when setting up the PL3, as shown in FIG. 3B, the applied voltage must be increased to the discharge voltage of the gas (particularly, a high voltage is required at atmospheric pressure). Its sustaining voltage is much lower and so much higher voltage is not needed. In order to have such characteristics, a Tesla coil 7 as shown in FIG. 1A is usually used as an auxiliary device for high voltage (for example, 50 to 60 KV) and low current. It will be cleared.

By the way, as for the discharge tube,
As shown in (i) and (ii) of (a), a single structure and a double structure including an outer tube and an inner tube are used. Here, the purpose of forming a double tube is as shown in FIG. C) (i), (i) of (b)
This is for setting the plasma PL at the center of the discharge tube as shown in i). This central part is particularly effective in the case of helium plasma. At this time, quartz is used for the outer tube of the discharge tube, and quartz is used for the inner tube (metal may be used because the inner tube does not directly contact the plasma).

<Problem to be Solved by the Invention> Such a conventional technique has the following problems.

: A high voltage device and a probe for discharging from outside the discharge tube are required, and high voltage is applied, so that strong noise is generated and not only malfunctions of peripheral devices but also damage in some cases. is there.

： Complication of equipment such as insulation treatment accompanying the generation of high voltage is also caused.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide a microwave induction device having a simple structure without fear of malfunctioning or damaging other devices due to noise or the like. It is to provide a plasma ignition device.

<Means for Solving the Problems> In order to achieve such an object, the present invention provides a discharge tube having a double structure including an inner tube and an outer tube, which supplies a microwave through a cavity to a plasma gas. In the microwave induction plasma igniter for generating plasma in the discharge tube to which the microwave is supplied, at least one of the discharge tube and the cavity is moved, and a tip of the inner tube is inserted into a position where the microwaves are concentrated. Moving means for returning the tip of the inner tube to a fixed position after generating plasma in the discharge tube.

<Action> Using a conductive object such as SUS or Cu for the content (this case is described using SUS), moving at least the inner tube of such a discharge tube along the cavity. (Or, conversely, the cavity is moved to the discharge tube side.) As a slide mechanism that allows the inner tube to be inserted into the cavity during ignition, a current is generated in the inner tube to emit thermoelectrons during ignition By doing so, the ignition is performed, and a high-voltage generating device is not required, and the whole structure has a simple structure that does not cause any trouble (malfunction or damage of other devices due to noise or the like).

<Examples> Hereinafter, the present invention will be described with reference to the drawings with reference to specific examples.

In the following drawings, the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

 FIG. 1 is a diagram showing a specific embodiment of the present invention.

In FIG. 1, reference numeral 71 denotes a discharge tube having a double structure including an inner tube 71b and an outer tube 71a. At this time, S
A US conductive object is used, and a non-metallic tube such as quartz or alumina that can withstand high temperatures is used for the outer tube 71a. Reference numeral 73 denotes a block 73 for continuing and supporting the outer pipe 71a by the inner pipe 71b and the pipe joint 72. 74 is a slide mechanism including a slide table 74a and a fixed table 74b. The fixed table 74b is fixed to the base 75. A block 76 for fixing and supporting the cavity 5 is also fixed to the base 75.

As a result, the distal end portion 71b ₁ of the inner tube 71b, the number from the cavity inner surface In the position (i.e. indicated by a solid line position)
mm (the position on the left side in the figure) (the distance between the tip portion and the cavity surface at this lowered position is represented by τ).

Then, by moving the slide table 74a along the center hole of the cavity 5 to the right in the direction of the arrow θ in the figure to the position indicated by the broken line, the outer tube 71a of the discharge tube also moves to the right with the inner tube 71b. 71b is fully inserted inside the cavity. The slide table 74a is returned from the position of the broken line to the original position (the position of the solid line).
As a result, everything becomes the original home position.

The operation function of igniting by emitting current by generating an electric current in the inner tube by inserting the inner tube into the cavity at the time of ignition in such a structure is as follows.

(A) A predetermined flow rate (for example, 250 ml / min as in the above example) of PLG2 flows into the discharge pipe inner pipe 71b from the aspirator 10 shown by a broken line, for example.

(B) A microwave 4 having a predetermined output of, for example, 100 W is applied to the cavity 5.

(C) The slide table 74a is moved as indicated by the arrow θ to insert the discharge tube inner tube 71b into the cavity 5.

(D) As shown by the broken line, thermoelectrons are emitted from the inner tube 71b inserted into the cavity, thereby increasing the number of ionized electrons. As a result, the PLG2 is hit, PL3 rises, and the discharge starting voltage drops.

(E) When the PL stands, the slide table 74a is moved to return the discharge tube inner tube 71b to the fixed position shown by the solid line in the figure.

The moving means of the microwave induction plasma ignition device of the present invention is not limited to the above description, but may be as follows.

(I) The slide table 74a may be moved manually, or a moving means such as a motor may be used.

(II) In the above description, the case where the outer tube and the inner tube are moved together has been described, but it goes without saying that only the inner tube may be moved.

(III) Since it is only necessary that the discharge tube inner tube can be inserted into the cavity, the fact that the discharge tube may be fixed and the cavity may be moved is a design matter that can be naturally considered from the above description.

<Effects of the Invention> Since the present invention is configured as described above,
The following effects are obtained.

: Since no noise is generated at the time of ignition, there is no possibility of malfunction or damage of other devices arranged in the vicinity.

: Since there is no high voltage generating section, an insulating structure or the like is not required, so that the entire structure can be made simple.

: There is no risk of electric shock due to no high voltage generator.

[Brief description of the drawings]

FIG. 1 is a diagram showing a specific embodiment of the present invention, and FIG. 2 is a diagram provided for explaining a conventional technique. 1 ... discharge tube 2 ... plasma gas (PL
G), 3 ... plasma (PL), 5 ... cavity, 71
... Discharge tube.

Claims (1)

(57) [Claims] 1. A microwave induction plasma igniter for supplying a microwave to a discharge tube having a double structure including an inner tube and an outer tube via a cavity to generate plasma in the discharge tube to which a plasma gas is supplied. After moving at least one of the discharge tube or the cavity and inserting a tip of the inner tube at a position where the microwaves are concentrated to generate plasma in the discharge tube, the tip of the inner tube is A microwave induction plasma igniter, comprising: moving means for returning to a home position.