Plasma sheath ground simulation electromagnetic experiment device and using method

Abstract

The invention discloses a plasma sheath ground simulation electromagnetic experiment device and an application method, and the experiment device comprises a plasma generator, a spray pipe and a plasmadiagnosis system; the plasma generator is used for ionizing a neutral gas to generate high-temperature plasma; the spray pipe is used for accelerating the plasma by utilizing an aerodynamic principleand shaping the cross section of the plasma jet flow in a vacuum dark chamber; and the plasma diagnosis system is used for diagnosing the electron density of the plasma jet flow in real time througha non-contact method and feeding back the electron density to a comprehensive controller, and the comprehensive controller compares the actually measured electron density with a preset electron density value, and the power supply output power of the plasma generator is adjusted through feedback to realize continuous and stable control of the electron density of plasma jet. The plasma jet flow generated by the invention is stable and controllable, the electron density range is wide, the collision frequency range is wide, the length is large, the components are pure, and the regulation and control of the non-uniform distribution of the plasma electron density can be realized.

Description

technical field [0001] The invention belongs to the technical field of electromagnetic measurement, and relates to a plasma sheath ground simulation electromagnetic experiment device and a use method. Background technique [0002] When the aircraft is flying at a high speed above Mach 5 in the adjacent space, the aerodynamic heating effect will ionize the air to form a plasma sheath covering the aircraft. The plasma sheath is composed of a large number of free electrons, positive ions and neutral molecules. , it will attenuate the electromagnetic wave signal, and in severe cases, it will cause a communication blackout phenomenon. When the radar detects a high-speed aircraft, the echo signal will be reduced or distorted due to the existence of the plasma sheath. In order to carry out electromagnetic experiments under the plasma sheath on the ground, it is necessary to generate a plasma jet with pure components, long time, wide range of electron density and collision frequency...

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Problems solved by technology

The shock tunnel / shock tube uses high-pressure gas to rupture the membrane to generate supersonic shock waves, and compresses the gas in the experimental section to generate high-temperature plasma, whose electron density can reach 10 13 cm -3 , but the stable duration of the shock wave wind tunnel is very short, generally a few milliseconds to hundreds of milliseconds, it is difficult to perform long-term continuous experiments such as antenna characteristic measurement and communication system verification; in addition, the repeatability of the experiment is poor; the arc wind tunnel uses The high-power arc generated by the discharge of the positive and negative electrodes heats the air to a state of high temperature and high pressure, which can provide a long-term stable high-enthalpy plasma jet, but due to the pollution of metal copper, ions and other electrode powders in the flow field, it changes to a certain extent The electric wave propagation characteristics of the plasma; the inductively coupled plasma wind tunnel uses induction heating to generate a pure high-enthalpy plasma jet that runs stably for a long time. Under normal conditions, the electron number density ranges from 10 10 ~10 13 cm -3 , the collision frequency range is 10 9 ~10 10 Hz, but due to the high temperature of the generated plasma, it is difficult to diagnose and control the plasma in real time, resulting in poor repeatability and poor controllability of the experiment.

In addition, the current thermal plasma experimental equipment is mainly used to simulate the high enthalpy characteristics of the plasma sheath, and to carry out high-temperature assessment experiments on materials. The experimental section is small, with a maximum of about 2m, and the electromagnetic wave reflection is serious, which is not conducive to electromagnetic experiments under plasma.

[0005] In recent years, cold plasma source simulation equipment has been widely used in the study of radio wave propagation characteristics due to its advantages of miniaturization, controllability, and relatively low cost. The typical representative is the large-area plasma generated by the principle of glow discharge. However, limited by the principle of glow discharge, the device can only work under low pressure, and the highest plasma electron density can only reach 10 11 cm -3 order of magnitude, and the collision frequency is less than 1GHz

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