Arc Jet Measurements Related to Ablation Test Validity

Abstract
This paper discusses the importance of obtaining an accurate, detailed calibration of arc jet tunnel flows in order that materials test data can be properly interpreted. Various measuring techniques useful in providing the gas dynamic calibration of the flow are described. Certain gas kinetic measurements (spectroscopy, Langmuir probes, etc.) are also briefly discussed. Experimental data from the 150-kw arc tunnel are presented. The necessary conditions for valid free-flight simulation, as well as the possibility of attaining these conditions in an arc jet, are defined briefly. Also, the problem of scaling is discussed and several possible methods of scaling are suggested.