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 of the excited state H-2(d(2) Pi(u)) has been determined by analyzing the intensity distribution of the spectral lines of the Fulcher-alpha system of H-2. The gas temperature in the plasma, which is twice the value 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 similar or equal to 1.4 eV), (2) appearance of the Fulcher-alpha system of H-2 (excitation potential Delta E=13.87 eV), (3) low rotational temperature (T-rot*similar 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 density of hydrogen atoms and hydrogen dissociation degree in the plasma. The measured absolute density of hydrogen atoms are in the (1-1.4)x10(20) m(-3) range, and the corresponding dissociation degree of the hydrogen plasma is in the range of 8%-13%. (C) 1996 American Institute of Physics.