| Summary: | We have proposed Rotating Magnetic Field (RMF) acceleration method as one of
electrodeless plasma accelerations. In our experimental scheme, plasma generated by an rf
(radio frequency) antenna, is accelerated by RMF antennas, which consist of two-pair,
opposed, facing coils, and these antennas are outside of a discharge tube. Therefore,
there is no wear of electrodes, degrading the propulsion performance. Here, we will
introduce our RMF acceleration system developed, including the experimental device, e.g.,
external antennas, a tapered quartz tube, a vacuum chamber, external magnets, and a
pumping system. In addition, we can change RMF operation parameters (RMF applied current
IRMF and RMF current phase difference ϕ,
focusing on RMF current frequency fRMF) by adjusting matching
conditions of RMF, and investigate the dependencies on plasma parameters (electron density
ne and ion velocity vi); e.g.,
higher increases of ne and vi
(∼360 % and 55 %, respectively) than previous experimental results were obtained by
decreasing fRMF from 5 MHz to 0.7 MHz, whose RMF penetration
condition was better according to Milroy’s expression. Moreover, time-varying component of
RMF has been measured directly to survey the penetration condition experimentally.
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