MCP (microwave coupled plasma) resonant cavity

Abstract

The invention discloses an MCP (microwave coupled plasma) resonant cavity, and belongs to the technical field of microwave application. The structure of the MCP resonant cavity comprises an outer conductor (1), a microwave antenna (2), an inner conductor (3), a sample inlet (7), a gas maintaining inlet (10), a gas shielding partition plate (11), a gas shielding inlet (12), a cooling ring (13), a gas shielding choke cone (14) and an impedance matching cone (15). The design of the MCP resonant cavity increases the power density of a plasma, and further increases the volume of a plasma torch, so that the bearing capability and the excitation capacity of a torch sample are stronger, a gaseous sample or an atomized water solvent sample and an organic solvent sample can be directly introduced to be measured. The MCP resonant cavity disclosed by the invention further has the characteristics of high stability, wide application range and the like.

Description

technical field [0001] The invention belongs to the field of microwave application technology, and in particular relates to a microwave coupling plasma resonant cavity which can be used in the field of analytical instruments. Background technique [0002] Microwave plasma resonant cavity plays an important role in the field of analytical instruments. It is an important part of spectrometers and mass spectrometers. It can be used as an excitation source for atomic emission spectrometers and as an ion source for mass spectrometers. The closest prior art with the present invention is the Chinese patent "Microwave Plasma Torch" (abbreviated as MPT) whose publication number is CN94205428.8. figure 1 As shown, it consists of an outer conductor, an inner conductor and a sample tube. The sample tube passes through the dry sample aerosol, and enters the central channel of the plasma for excitation and ionization. A sustaining gas is passed between the sample tube and the inner cond...

AI Technical Summary

Problems solved by technology

However, the method of simply increasing the incident power has been proved to be limited in practice, because the cavity size of the torch is relatively small, so the power capacity of the cavity is limited

Even if a high-power microwave source is used to input excessive microwave power, the increase in plasma electron density is limited, and the excess microwave energy can neither be reasonably received by the cavity nor completely consumed by gas ionization

Among the microwave energy that cannot be absorbed and utilized, part of it returns to the absorbing load in the microwave power source as reflected power, which is wasted as useless power; the other part leaks into the surrounding space, and part of the microwave power is lost inside the cavity, which increases the heating of the cavity

[0004] On the other hand, simply enlarging the cavity size of the original torch in proportion, this technical route has also been proved repeatedly by practice to be unfeasible

Simply increasing the size of the torch without increasing the power density at the same time will lead to abnormal shape of the plasma, or unstable state of the plasma, which will not improve the sample tolerance and excitation ability of the plasma at all.

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