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Indexed by:期刊论文

Date of Publication:2019-05-07

Journal:JOURNAL OF APPLIED PHYSICS

Included Journals:EI、SCIE

Volume:125

Issue:17

ISSN No.:0021-8979

Key Words:Antennas; Carrier concentration; Electromagnetic induction; Electron density measurement; Electron temperature; Electrons; Energy transfer; Ion sources; Radio waves, Analytic solution; Driving frequencies; Effective electrons; Fundamental properties; Inductively-coupled; Negative hydrogen ions; Power transfer efficiency; Radio frequency power, Efficiency

Abstract:The radio frequency power transfer efficiency is experimentally and numerically investigated in an inductively coupled negative hydrogen ion source. The discharge is operated in a low pressure range of 0.1-3 Pa at a driving frequency of 2 MHz and an applied power of up to 6 kW. In the experiment, the power transfer efficiency value is determined by measuring the applied power and current through the antenna coil both with and without discharge operation. Fundamental properties, such as electron density and effective electron temperature, are obtained by means of a Langmuir probe. The effect of the antenna coil turns, N, is also studied in a range of 5-9 turns. It is found that more coil turns can significantly enhance the power transfer efficiency due to the remarkably increasing quality factor of the system. Moreover, the experimental results show that the power transfer efficiency first increases and then reaches the maximum with increasing applied power, while it first increases quickly and then rises at a slower rate with increasing gas pressure. In order to give a comprehensive knowledge of the power absorption mechanism, a self-consistent hybrid model is developed. It is found that the numerical results are in reasonable agreement with that measured in the experiment. The numerical results and the analytic solutions in the limit cases of low and high pressures can well explain the various trends of the power transfer efficiency obtained in the experiment. These trends mainly depend on the quality factor Q, the electron density, and the effective electron collision frequency. Published under license by AIP Publishing.