Plasma Acceleration by Rotating Magnetic Field Method using Helicon Source*

Electrodeless plasma thrusters are very promising due to no electrode damage, leading to realize further deep space exploration. As one of the important proposals, we have been concentrating on Rotating Magnetic Field (RMF) [1] acceleration method [2,3]. High-dense plasma (up to 10$^{\mathrm{13}}$ cm$^{\mathrm{-3}})$ can be generated by using a radio frequency (rf) external antenna, and also accelerated by an antenna wound around outside of a discharge tube. In this scheme, thrust increment is achieved by the axial Lorentz force caused by non linear effects. RMF penetration condition into plasma can be more satisfied than our previous experiment [4], by increasing RMF coil current and decreasing the RMF frequency, causing higher thrust and fuel efficiency. Measurements of AC RMF component s have been conducted to investigate the acceleration mechanism and the field penetration experimentally. [1] I. R. jones, \textit{Phys. Plasmas} \textbf{6} (1990) 1950. [2] S. Shinohara \textit{et al.}, \textit{IEEE Trans. on Plasma Sci.} \textbf{42} (2014) 1245. [3] S. Otsuka \textit{et al.}, \textit{Plasma Fusion Res.} 10 (2015) 3401026. [4] T. Furukawa \textit{et al.}, \textit{Phys. Plasmas} \textbf{24} (2017) 043505.