Reverse plasma motion driven by moderately screened rotating electric field in an electrodeless plasma thruster

A reversely-induced azimuthal current has been found in two-dimensional particle simulations with moderately screened rotating electric field (REF) though an ideally penetrating REF drives a "positive" azimuthal current following rotating E × B drifts. This brings us an alternative acceleration concept, called a negative-moving response (NMR) acceleration, of the helicon plasma under practical conditions using a converging magnetic field because the internal electric potential, formed by the plasma response against the external field, drives the "negative" azimuthal current. Under realistic experimental conditions, e.g., a magnetic field of 0.2 T, AC frequency of <100 MHz, and AC voltage of <1000V, the resultant thrust can be estimated at an observable level of >0.1mN with the NMR acceleration. Moreover, the reverse REF is more favorable to the NMR acceleration than the conventional forward one because the reverse field produces a Lissajous acceleration in the converging magnetic field.