Microwave plasma torch device

Abstract

The invention provides a microwave plasma torch device which comprises a cavity part, a microwave coupling part and a tuning part. The cavity part comprises an inner tube, a middle tube and an outer tube, wherein the inner tube, the middle tube and the outer tube are successively coaxially arranged from the inside out. One end of the cavity part is open. The tuning part is arranged on the other end to adjust the field strength of the open end. A microwave coupling opening is arranged in the side wall of the outer tube. The microwave coupling part and the cavity part are in microwave coupling through the microwave coupling opening. A first microwave resonant cavity is formed between the outer tube and the middle tube. A porous pad which is used for coaxially fixing the inner tube and the middle tube is arranged between the inner tube and the middle tube. The first microwave resonant cavity couples microwave into a space between the inner tube and the middle tube through the open end of the cavity part to form a second microwave resonant cavity. The upper surface of the porous pad is the reflective surface of the second microwave resonant cavity. The microwave plasma torch device provided by the invention has the advantages of wide application power range and excellent plasma gas stability, and further avoids a series of problems caused by superposition of high-strength electric field pyrogenicity and a plasma heat source.

Description

technical field [0001] The invention belongs to the technical field of spectral analysis, and in particular relates to a microwave plasma torch device, which can obtain plasma with excellent stability and is suitable for power conditions ranging from several watts to over kilowatts. Background technique [0002] The torch tube of MPT (microwave plasma torch) is usually a three-tube coaxial structure with one end open. The microwave is coupled into the torch tube, and the plasma gas is excited at the open end of the torch tube to generate plasma, so that the sample can be analyzed by spectrum after passing through the plasma. [0003] Due to the small volume of the plasma formed by the hundred-watt-level MPT, the gas temperature is low (2100K), and the sample stays in the plasma for a short time, which is not conducive to the completion of evaporation, desolvation, and atomization of the sample aerosol when passing through the plasma light source. , ionization, excitation, e...

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Problems solved by technology

[0004] In addition, two strong electric fields need to be formed in the MPT structure, one is used to couple microwave energy into the MPT cavity, and the other is used to excite and maintain plasma. In the existing design, the spatial distribution of the two strong electric fields is basically superimposed, Under high power conditions, the plasma stability and microwave transmission efficiency will interfere with each other, and the high temperature of the plasma will cause the microwave transmission efficiency to decrease.

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