Experimental investigation of supersonic plasmas flow fields modification by magnetic fields

摘要

During the atmospheric re-entry phase, the formation of plasma around the vehicle entails high thermal stresses threatening the protection of the spacecraft. In addition, the phenomenon of "Blackout" appears, preventing all radio transmissions. This experimental work is the subject of preliminary studies on the interaction of a magnetic field with supersonic plasma developed around an obstacle. Previous works showed the effects due to the interaction of the magnetic field with the plasma. This study was carried out with air plasmas and argon plasmas and two geometries have been studied: a blunt body and a flat plate. Different diagnostics were used for the analysis of the plasma flow field, two non-intrusive tools like a CCD camera and an optical spectrometer and two intrusive tools like electrostatic probes and Pitot probes allowing local measurements. The analysis of the images shows that the plasma flow field is modified in the presence of magnetic field; these results are confirmed by optical spectroscopy measurements showing that the magnetic field mainly affects the vibrational temperatures. Finally, it was found that the electron parameters are strongly modified presenting a strong decreasing of the electron density.