Non-jet normal-pressure large-volume microwave plasma generation method

Abstract

The invention discloses a non-jet normal-pressure large-volume microwave plasma generation method, and belongs to the technical field of microwave plasmas. The method is characterized by comprising the following steps: a, starting an igniter, and spraying generated small plasmas or chemical flames into a conical cavity; b, starting a microwave source, and inputting microwaves into a reaction cavity through a microwave feed port; and c, turning off the igniter, increasing the microwave power of the microwave source, and amplifying the small plasmas in the conical cavity to obtain non-jet normal-pressure high-power and large-volume microwave plasmas. According to the invention, to-be-treated gas can be fully and uniformly heated, so that the reaction efficiency is improved; uniform distribution in a set space range is realized, destructive breakdown discharge can be effectively prevented, and heat dissipation balance is easy to control; reasonable temperature, stable structure and long-term operation stability of the whole generator are ensured under the condition of reducing heat dissipation as much as possible; and the whole operation process is simple, reliable and easy to control.

Description

technical field [0001] The invention relates to the technical field of microwave plasma, in particular to a non-jet flow atmospheric pressure large-volume microwave plasma generation method. Background technique [0002] Plasma is the fourth state of matter. It usually refers to ionized or partially ionized conductive gas, which includes six typical particles: electrons, positive ions, negative ions, atoms or molecules in the excited state, and atoms or molecules in the ground state. molecules and photons. Whether it is partially ionized or completely ionized; the total number of negative charges in it is equal to the total number of positive charges, so it is called plasma, which is electrically neutral as a whole in the time and space of the macro scale. A stricter definition is: Plasma is a collection of electrons, positive ions and neutral particles that is electrically neutral as a whole. [0003] Plasma is divided into two categories according to temperature: high-te...

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Problems solved by technology

However, a large amount of auxiliary gas is required to effectively confine and orient the plasma, and a large amount of gas to be treated cannot pass through the plasma region and cannot produce effective reactions; and the gas passing through the plasma region may have adverse side reactions due to excessive temperature, making the Material utilization, processing efficiency and processing effect have all become poorer

In addition, if the microwave power is too large and the plasma temperature and concentration are too high, it will be difficult for the auxiliary gas to reliably confine the plasma and form a jet, which will eventually lead to unstable operation or damage to the device

Moreover, the addition of a large amount of auxiliary gas not only increases the processing burden of the microwave plasma device, but also increases the separation burden of subsequent devices, and also reduces the reaction efficiency.

In addition, because the plasma start-up area of ​​this type of device is the same area as the subsequent continuous work area, the microwave power density in the work area is very high during low-power operation. If a high-power plasma device is required, the microwave power density in the work area, plasma The body temperature and concentration will be extremely high. At this time, limited by the microwave transmission system structure and heat dissipation, the microwave power that can be loaded is small and the upper limit of the power is low, which is greatly limited. For industrial applications, tens of kilowatts, hundreds of kilowatts, The long-term continuous application of the kilowatt level is still unsatisfactory

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