Laser absorption spectroscopy diagnostics in the arc-heater of an arcjet facility
Zeng Hui;Chen Lianzhong;Lin Xin;Ou Dongbin;Dong Yonghui;Beijing Key Laboratory of Arc Plasma Application Equipment,China Academy of Aerospace Aerodynamics;Institute of Mechanics,China Academy of Science;
Gas temperature and species number density are the key parameters to quantitatively assess the arc-heated wind tunnel operation and flow quality.Conventional techniques meet great challenge in high enthalpy flow diagnostics for arc-heated facilities under prolonged operation at high temperatures.Based on the local thermodynamic equilibrium plasma assumption,this paper presents in-situ diagnostics for the dissociated air(5000K)in the arc heater by using laser absorption spectroscopy of atomic oxygen at the wavelength of 777.19 nm.The gas temperature and the number density of atomic oxygen are measured under two operation conditions of H0=15.8MJ/kg and 17.4MJ/kg,respectively.The average temperatures are 5843 Kand 6047K,corresponding to 5950 Kand 6335Kfrom charts for high temperature equilibrium flow properties of air.The number density of atomic oxygen is within(1.1~1.2)×1018cm-3 and is in consistency with the calculation via NASA-CEA program,while the number density of atomic oxygen(5S02)is within(1.0~1.5)×1010cm-3.This work demonstrates that the laser absorption spectroscopy is applicable for high enthalpy flow diagnostics in the arc-heated wind tunnel as a new technique.
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