Analysis of the argon additive influence on a nitrogen arcjet flow

Abstract

Two plasma wind tunnels for the simulation of conditions encountered by space vehicles during planetary entry, and for the development and qualification of heat protection material, are in use at the Institute for Space Systems. The plasma is produced by a magnetoplasmadynamic (MPD) accelerator, specially designed for the use of gas mixtures such as N 2 /O 2 and carbon containing gas mixtures. At high mass flow rates and low power levels a protective gas layer of argon is produced at the anode for a N 2 /O 2 flow. The influence of the Ar additive on a nitrogen plasma is investigated experimentally by means of electrostatic probes, mass spectrometry, pitot probes, and heat flux probes; and numerically with a program especially developed for the simulation of the high enthalpy flowfield of MPD accelerators. The existing numerical code for solving the chemical reactions within an air plasma was extended by argon/air reactions. A comparison between the experimental data set and the numerical simulation of the plasma flow is made for a N 2 and a N 2 /Ar plasma.

Mass spectrometric investigation of high enthalpy plasma flows

“…8 the data so corrected are compared with a numerical simulation, which has been presented elsewhere in detail. 14 - 27 As seen in the figure, the mass-spectrometric data are in good qualitative and quantitative agreement with the theoretical predictions. Radial distributions of ions could not be determined because a high recombination rate of the ions leads to very low count rates at the stagnation point and at a too high pressure inside the spectrometer.…”

“…The plasma conditions examined within this test case 14 - 27 are at an ambient pressure of 1.3 mbar leading to a total pressure of 3 mbar in the center of the jet, a current of 1000 A and 1.0 g/s N 2 without anode protection gas. An average specific enthalpy of 33 MJ/kg is reached at the end of the anode.…”

Chemical non-equilibrium modelling of an argon–oxygen supersonic ICP

“…Although several modelling studies have been conducted on ICPs in conditions close to those studied in this work, only a few [10,11] include the modelling of an RF induction torch, a converging-diverging duct and a free expansion zone. The attention of most authors has been devoted either to the induction zone, where plasma is generated by assuming LTE [12][13][14][15][16][17][18][19][20] and non-LTE conditions [21][22][23][24][25][26][27][28][29], or to the characteristics of the jet at the exit of the convergentdivergent nozzle, neglecting the effect of the plasma coupling of the electromagnetic and aerodynamic fields and assuming LTE [30][31][32][33] or taking into account the deviation from LTE [5,[34][35][36][37][38][39][40][41][42]. The advantage of these numerical models is that they give detailed information on the characteristics of the jet at the exit of the plasma torch.…”