Author(s): Ma Chao, Zhao Gao, Liu Zhongwei, Sang Lijun, Chen Qiang, Laboratory of Plasma Physics & Materials, Beijing Institute of Graphic Communication
Pages: 989-993
Year: 2015 Issue:  8
Journal: Vacuum Science and Technology
Keyword:  Helicon plasma; Frequency-compensated; Mode transition; The density peak at low magnetic field;
Abstract: The dependence of thedischarge in the helicon plasma on the discharge conditions,including but not limited to the discharge power,pressure and magnetic field,was experimentally evaluated with a single frequencycompensated Langmuir probe. The results show that as the discharge power increased,the electron density increased,rising up abruptly at discharge powers of 300 and 900 W,respectively. The "jumps"of the electron density suggest a transition from the capacitively-coupled discharge mode to a whistle wave discharge mode. We found that the increases of both the pressure and magnetic field reduce the threshold of the discharge power for the transition of the discharge mode. In addition,a high electron density peak in the low magnetic field in the upstream of the antenna was observed,possibly because of the discharge mode of the helicon wave.