Development of High-Density Radio Frequency Plasma Sources With Very Small Diameter for Propulsion

作者：Shinohara Shunjiro^*; Kuwahara Daisuke; Ishii Takamichi; Iwaya Hiraku; Nishimura Shuichi; Yamase Tomoya; Arai Daisuke; Horita Hirotaka

来源：IEEE Transactions on Plasma Science, 2018, 46(2): 252-262.

DOI：10.1109/TPS.2017.2776110

• Helicon
• plasma production
• plasma propulsion
• radio frequency (RF)

Radio frequency (RF) plasma sources, especially helicon ones, are very useful in many fields, because of the high-density (up to similar to 10(13) cm(-3)) and low electron temperature (from a few to several electronvolts) available, using an RF frequency range. Here, we develop and characterize very small-area (from 2-cm down to 0.1-0.3 cm in diameter) RF sources that are useful for a space propulsion system with an advanced concept of an electrodeless condition (no direct contact between the plasma and electrodes), leading to a longer operation lifetime. Measurements by using electrostatic probes as well as by a spectrometer based on the collisional radiative model in a small plasma region were employed to estimate the electron density n(e) and its temperature. Here, n(e) was measured as a function of the input RF power and RF excitation frequency, especially in a higher frequency range than the usual one of similar to 14 MHz, under the mirror magnetic-field configuration. The electron cyclotron resonance effect in the divergent field was examined under a weaker magnetic field with the RF frequency lower than those generally employed. The particle production efficiency, even in this small source, showed an excellent performance, based on classical diffusion discussions. In addition, applying these sources were applied to a space propulsion system with the concept of the m (azimuthal mode number) = 0 half-cycle acceleration, which was operated under all electrodeless conditions in both the plasma generation and electromagnetic acceleration phases.

• 出版日期2018-2