Transient microwave reflection measurement method and device for plasma complex dielectric constant

Abstract

The invention belongs to the technical field of plasma diagnosis, relates to a microwave measurement technology and in particular relates to a transient microwave reflection measurement method and device for a plasma complex dielectric constant. The measurement device provided by the invention is provided based on a shock tube experiment platform; the measurement method is used for processing a received reflection signal through a calibration and canceling technology to obtain a real reflection coefficient on the surface of a tube wall of a shock tube, and influences on a self-reflection signal of a testing system are removed; then changes of the plasma complex dielectric constant in the shock tube is reversely deduced by utilizing the reflection coefficient on the surface of the tube wallof the shock tube; meanwhile, aiming at the problem that a function for reversely deducing the plasma complex dielectric constant by the reflection coefficient of the tube wall of the shock tube hasambiguity, the problem is solved by utilizing approximation of linear changes of the complex dielectric constant of a plasma within short time, so that the transient measurement of the plasma complexdielectric constant is effectively realized.

Description

technical field [0001] The invention belongs to the technical field of plasma diagnosis, relates to microwave measurement technology, and specifically provides a plasma complex permittivity transient microwave reflection measurement method and device based on a shock tube experimental platform. Background technique [0002] As the fourth state of matter different from solids, liquids and gases, plasma is mainly composed of charged ions and free electrons. It presents a highly excited unstable state, so it is difficult to persist in the natural environment. There are many ways to artificially generate plasma. As a device for generating high-density plasma used in experimental research, the shock tube can only be generated inside it and lasts for only a few hundred microseconds. Although Lang The Muir probe diagnostic method has been applied to measure the plasma electron density and collision frequency, but because the characteristics of its interventional method will affect ...

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Problems solved by technology

There are many ways to artificially generate plasma. As a device for generating high-density plasma used in experimental research, the shock tube can only be generated inside it and lasts for only a few hundred microseconds. Although Lang The Muir probe diagnostic method has been applied to measure the plasma electron density and collision frequency, but because the characteristics of its interventional method will affect the density distribution of the plasma in the tube and cause test errors, the microwave diagnostic method is used to measure the plasma electron density and the Non-contact measurement of collision frequency has better application prospects

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