DIAGNOSTICS OF THE MAGNETIZED LOW-PRESSURE HYDROGEN PLASMA-JET - MOLECULAR REGIME

Optical emission and absorption spectroscopy and double Langmuir probe diagnostics have been applied to measure the plasma parameters of an expanding magnetized hydrogen plasma jet. The rotational temperature o f the excited state H-2(d(2) Pi(u)) has been determined by analyzing t he intensity distribution of the spectral lines of the Fulcher-alpha s ystem of H-2. The gas temperature in the plasma, which is twice the va lue of the rotational temperature is equal to similar or equal to 520 K. Several clear indications of presence of the ''hot'' electrons have been observed in the plasma: (1) Langmuir probe measurements (T-e sim ilar or equal to 1.4 eV), (2) appearance of the Fulcher-alpha system o f H-2 (excitation potential Delta E=13.87 eV), (3) low rotational temp erature (T-rotsimilar or equal to 260 K) of the excited H-2(d(3) Pi(u )) molecules, (4) local excitation in the plasma of Ar I(Delta E=15.45 eV), and Ar II(Delta E=19.68 eV) spectral lines, (5) local excitation in the plasma of He I(Delta E=23.07 eV and Delta E=24.04 eV) spectral lines. Optical actinometry has been applied to measure the absolute d ensity of hydrogen atoms and hydrogen dissociation degree in the plasm a. The measured absolute density of hydrogen atoms are in the (1-1.4)x 10(20) m(-3) range, and the corresponding dissociation degree of the h ydrogen plasma is in the range of 8%-13%. (C) 1996 American Institute of Physics.