Axial distribution of a VHF H2 plasma produced by a narrow gap discharge

A capacitively coupled VHF H-2 plasma was produced with a conventional parallel plate electrode of 400 x 300 mm(2). Axial distributions of the plasma parameters were examined using a movable Langmuir probe. The electron density had a hill-like profile near the center while the electron temperature around the discharge electrode was higher than that near the center. It was found that the axial distribution of the plasma potential was considerably different from that based on ohmic heating. The measured sheath potentials around the discharge electrode were lower than the theoretical potentials. A simulation using a hybrid model was performed and compared the results with the experimental results. (C) 2016 The Japan Society of Applied Physics