JPS6286700A - Electrodeless radio frequency plasma reactor - 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 A. OBJECTS OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-frequency plasma reactor for producing highly pure reaction products.

[Conventional technology]

Generally, high-frequency plasma has a large volume and a plasma flame with a relatively low flow rate because the thermal pinch effect and magnetic pinch effect are not so large.

This means that if the reaction can be carried out in a high-frequency plasma flame, the reaction area will be large and the residence time of one reactive substance in the plasma will be long, and an effective plasma reaction can be carried out. Furthermore, since there is no electrode, there is no contamination caused by '1 separator substances, making it ideal for producing highly pure substances.

However, it is not easy to pass a reactive substance through the center of the plasma flame due to the backflow phenomenon caused by /a atmospheric pressure, and when a reactive substance is injected into the plasma flame, the plasma flame becomes unstable. The disadvantage is that the plasma flame is easily extinguished.

In order to solve these drawbacks, a high-frequency FII field-coupled arc plasma reactor equipped with a DC arc plasma torch using a tungsten cathode and a copper anode as discharge electrodes was invented (Japanese Patent Application No. 104830/1983 → Showa 55-3
(See Publication No. 2317).

In other words, the arc plasma is used as the seed for the high-frequency plasma flame, and even if the high-frequency plasma flame becomes unstable due to the introduction of reactive substances, the high-frequency plasma can operate and maintain stability due to the supply of ions and electrons from the arc plasma. The high kinetic energy of the arc plasma jet has made it possible to pass reactive substances through the center of the high-frequency plasma flame.

[Problem that the invention seeks to solve]

However, due to corrosion of the discharge electrode for generating DC arc plasma, the electrode material is mixed into the high-frequency plasma as an impurity, which is a serious drawback. Furthermore, due to corrosion of the electrodes, long-term operation cannot be achieved.

On the other hand, in recent years, reaction products of ultra-high purity are required in the development of new substances and new materials.

In view of the following points, the present invention is free from contamination due to electrode materials, and
The purpose of the present invention is to provide a high-frequency plasma reactor that can withstand long-term operation.

Summary: Structure of the Invention [Means for Solving the Problems] The present invention provides an auxiliary device that uses a high-frequency magnetic field to inductively generate high-frequency plasma at the top of the main plasma reactor, based on the same principle as the main plasma generation. This is a pyroelectrode high-frequency plasma reaction device characterized by being provided with an auxiliary plasma torch that generates a high-frequency plasma flame and superimposes it on the main plasma flame as a plasma jet.

[For production]

The plasma jet from the auxiliary plasma torch is ejected as seeds into the main high-frequency plasma, and the high-frequency plasma is superimposed on it, making it a kind of hybrid type electrodeless high-frequency plasma reactor.

Operates and maintains the main plasma flame stably. There is no predisposition to generate impurities and mix them into the high-frequency plasma, so it can withstand long-term operation.

〔Example〕

The figure is a longitudinal sectional view illustrating the electrodeless high-frequency plasma reactor of the present invention. A is the main plasma reactor, and B is an auxiliary high-frequency plasma torch installed above A.

A high frequency current is passed through the auxiliary plasma induction coil 1 to generate a high frequency magnetic field. When auxiliary plasma gas is injected into the quartz tube 3 through the injection port 2, the gas is inductively heated by the high frequency magnetic field and auxiliary plasma 4 is generated. At this time, in order to easily generate plasma, a voltage is applied to the Tesla coil 5 outside the tube, and the generated high pressure is used as a trigger.

The quartz tube 3 has a structure with a cooling space 3a, and by passing a cooling medium 6 therethrough, it cools and protects the nozzle 7 at the bottom of the quartz tube 3, and also prevents a thermal pinch effect on the plasma and the accompanying heat pinch effect. This produces a magnetic pinch effect and creates a plasma with a high energy density of 1.

Furthermore, the flow rate of the auxiliary plasma 4 is controlled by the injection pressure of the auxiliary plasma gas and the nozzle 7, and the auxiliary plasma 4 is ejected into the main plasma quartz tube 10 as a plasma jet.

Injected from the injection port 11, the main plasma induction coil 12
The main plasma gas heated by the high frequency magnetic field generated by the above is ignited by the auxiliary plasma 4, which serves as a seed, and becomes the main high frequency plasma flame (main plasma) 13.

The quartz tube lO has a structure with a cooling space 10a,
The cooling medium 14 cools and protects the tube surface, and the cooling gas 15 flows to cool the outer periphery of the plasma 13. Due to the thermal pinch effect and accompanying magnetic pinch effect, high energy is generated. It is a high-density F plasma.

On the other hand, the reactive substance injected from the injection port 11 enters and passes through the center of the main plasma 13 due to the kinetic energy of the auxiliary plasma 4.

In the experimental example, using a quartz tube 3 with a fi of 20 mmφ, argon gas was used as the plasma gas, and the coil 1 for auxiliary plasma induction was
A high-frequency power of MHz/2.5 kW is applied to generate auxiliary plasma 4, and this serves as a seed to generate an inner diameter of 60 m.
Main plasma induction coil 1 using mφ quartz tube IO
A high frequency power of 4 MHz and 35 kW is applied to the main plasma 13 to ignite the main plasma 13, and the main plasma 13 is maintained stable against the injection of reactive substances from the injection port 11. Confirmed that it is available.

C. Effects of the Invention The present invention is a so-called high-frequency plasma-high-frequency plasma hybrid system in which the auxiliary plasma 4 is superimposed on the main plasma 13.

(1) Since the auxiliary plasma 4 is used as a seed, it is possible to ignite it stably and to stably operate and maintain the main plasma 13 even when a reactive substance is injected.

(2) By using the auxiliary plasma 4 as a plasma jet, the kinetic energy of the auxiliary plasma 4 allows the reactive substance to pass through the center of the main plasma 13.

(1) A large area can be taken up for the reaction, which is unique to high-frequency plasma.

(2) The residence time of reactive substances in the plasma can be increased.

Possesses advantages.

Furthermore, since it is an electrodeless high-frequency plasma reactor, the number of electrodes is 114f+! This solves the above-mentioned drawbacks caused by the problem and also has the following effects.

(1) Ultra-high purity reaction products without contamination by electrode materials can be obtained. This, in combination with the above-mentioned effects, is extremely effective for the development and improvement of new substances and materials for compound synthesis, fine powder production, amorphous material production, etc.

(2) Can withstand long-term operation.

[Brief explanation of drawings]

The first time is a sectional view showing an embodiment of the present invention. A... Main plasma reactor, B... Auxiliary plasma torch, 1 fist 12... Coil for plasma induction, 2... Auxiliary plasma gas injection point, 11... Main plasma gas and reactive substance Note Inlet, 3.10...Quartz tube, 4...Auxiliary plasma, 5...Tesla coil, 6-14...Cooling medium, 7...Nozzle, 13...Main plasma, 15
...cooling gas.

Claims (1)

[Claims] (1) Generate high-frequency plasma inductively using a high-frequency magnetic field An auxiliary high-frequency plasma flame is generated on the top of the main plasma reactor using the same principle as the main plasma generation, and this is used as a plasma jet to generate the main plasma flame. An electrodeless high-frequency plasma reaction device characterized by being provided with a superimposed auxiliary plasma torch.