<title>Measurement of the local density in rarefied flows by means of characteristic fluorescence</title>

Abstract

ABSTRACT The new method is based on the interaction of fast beam electrons with electrons in the outer shells of atoms, which gener- ates the characteristic X-ray radiation. The intensity of X-rays is proportional to the concentration of the atoms in in- vestigated gas.The gasdynamic structures of rarefied argon jets were studied in the range of stagnation temperatures up to 5200 Kusing the this X-ray method. The experimental studies of the present work were performed in a low-density gasdynamic cham-ber. The arc heater was used as a gasdynamic source. The changes in the structure of a jet of monatomic gas beyond a sonicnozzle with variation in the rarefaction and the temperature factor have been clarified as a result of the experiments and gener-alisations performed.Keywords: electron-beam, local density, characteristic X-ray radiation, rerefied free jet 2. INTRODUCTION Today the electron beam is one of the main methods for investigation of rarefied gas flows allowing us to determine aseries of local parameters. The main idea of the active electron-beam method is to determine gas parameters based on theradiation spectrum excited by a fast electron beam. The above-mentioned spectrum covers the range from X-ray region to visi-ble one. The relation between the intensities excited by electron beam spectra and local gas parameters are provided eithertheoretically or by a calibration curve.The electron-beam technique is characterised by a good spatial localisation in combination with small disturbances in