Diagnosing ratio of electron density to collision frequency of plasma surrounding scaled model in a shock tube using low-frequency alternating magnetic field phase shift  

作　　者：吴明兴 谢楷 刘艳 徐晗 张宝 田得阳 Ming-Xing Wu;Kai Xie;Yan Liu;Han Xu;Bao Zhang;De-Yang Tian(School of Aerospace Science and Technology,Xidian University,Xi'an 710071,China;Hypervelocity Aerodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China)

机构地区：[1]School of Aerospace Science and Technology,Xidian University,Xi'an 710071,China [2]Hypervelocity Aerodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China

出　　处：《Chinese Physics B》2024年第5期519-530,共12页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.52107162 and 12202479);the Science and Technology Projects of Shaanxi Province,China(Grant Nos.2022CGBX-12 and 2022KXJ-57);the Science and Technology Projects of Xi’an City,China(Grant Nos.23KGDW0023-2022 and 23GXFW0011)。

摘　　要：A non-contact low-frequency(LF)method of diagnosing the plasma surrounding a scaled model in a shock tube is proposed.This method utilizes the phase shift occurring after the transmission of an LF alternating magnetic field through the plasma to directly measure the ratio of the plasma loop average electron density to collision frequency.An equivalent circuit model is used to analyze the relationship of the phase shift of the magnetic field component of LF electromagnetic waves with the plasma electron density and collision frequency.The applicable range of the LF method on a given plasma scale is analyzed.The upper diagnostic limit for the ratio of the electron density(unit:m^(-3))to collision frequency(unit:Hz)exceeds 1×10^(11),enabling an electron density to exceed 1×10^(20)m^(-3)and a collision frequency to be less than 1 GHz.In this work,the feasibility of using the LF phase shift to implement the plasma diagnosis is also assessed.Diagnosis experiments on shock tube equipment are conducted by using both the electrostatic probe method and LF method.By comparing the diagnostic results of the two methods,the inversion results are relatively consistent with each other,thereby preliminarily verifying the feasibility of the LF method.The ratio of the electron density to the collision frequency has a relatively uniform distribution during the plasma stabilization.The LF diagnostic path is a loop around the model,which is suitable for diagnosing the plasma that surrounds the model.Finally,the causes of diagnostic discrepancy between the two methods are analyzed.The proposed method provides a new avenue for diagnosing high-density enveloping plasma.

关 键 词：low-frequency alternating magnetic field phase shift shock-tube plasma diagnosis electron density collision frequency 

分 类 号：O53[理学—等离子体物理]