In the field of thermonuclear fusion reactor engineering as well as physics in the boundary region, to evaluate the characteristics of the hydrogen-deuterium mixed plasma as well as the pure hydrogen plasma and the pure deuterium plasma is also crucial issue. In this study, we examine Fulcher-α band spectrum of microwave discharge H2-D2 and H2-He gas mixture plasmas with their discharge pressure about 1 Torr, and determine rotational and vibrational populations of the upper state of the Fulcher-α band, d 3Πu state. The observed vibrational temperature is almost constant over the longitude area observed, about 0.4 eV. On the other hand, it is found that the rotational temperature becomes lower with increasing vibrational quantum number, and that its dependence is stronger for H2 plasma than for D2 plasma. First, we measure them for the pure H2 discharge and for the pure D2 discharge. The rotational temperature of highly vibrational levels of D2 molecule did not decrease with vibrational quantum number so remarkable as that of H2 molecule, i.e., T_rot^dv’(H2) > T_rot^dv’(D2) for v’ = 0, 1, and T_rot^dv’(H2) < T_rot^dv’(D2) for v’ = 2 – 4. It is considered that the angular momentum is conserved before and after the electron collision, which results in lowering of rotational energy with increasing vibrational quantum number. It was also found that the rotational temperature increases as the plasma goes to the downstream direction. It is considered that the electrons are excited mainly by the microwave under the present discharge condition, and relaxation process proceeds along with it to go to the downstream direction.
Next, the rotational and vibrational temperatures are examined as functions of H2/D2 mixture ratio in the feed gas, which reveals that high partial pressure of D2 increases the rotational temperatures for constant total discharge pressure, except for pure D2 discharge. Concerning H2-He mixture plasma, it is found that the high concentration of He raises the rotational temperature for the same discharge pressure. The results are discussed not only from the viewpoint of macroscopic difference of these discharge species like thermal conductivity but also from the microscopic point of view, such as mass differences or vibrational quanta.
各種検索
サポート
ヘルプ