"Get some gas, microwave it to make it really really hot, hold it in with magnets as long as possible, then when it escapes out the back it's going really fast, pushing the spacecraft forwards".
"The entire assembly is housed inside a tailored magnetic field called the “magnetic nozzle”. When an RF signal is applied to the antenna, the near-field pattern acts to ionize the propellant in the liner, and subsequently heat the plasma via stochastic electron-RF interactions [9, 10]. These interactions drive electrons out of the exit of the plasma liner. To maintain steady state charge balance, ions are accelerated by this momentary charge imbalance out of the liner, generating thrust. "
Essentially, instead of using an electric field generated by a anode/cathode grid to pull the ions out of the thruster, they are using the RF to generate free electrons which generate an electric field and pull the ions out of the container.
tldr: Simple/small thrusters getting within order of magnitude of performance of bigger/more complicated.
Introduction:
> “Electrodeless” RF thrusters are distinct from Hall effect thrusters, gridded ion engines, and gridded RF thrusters ... in that they do not use grids, anodes, cathodes, or high voltages to accelerate the propellant, greatly simplifying the thruster architecture. Their electrical and mechanical simplicity allows for electrodeless RF thrusters to be designed for the production requirements of the next generation of large satellite constellations.
> Despite their promise, electrodeless RF thrusters have not gained wide acceptance due to their sub-par measured performance compared to state of the art Hall effect and gridded ion systems.
> The Phase Four RFT approaches the concept of electrodeless RF plasma acceleration by acknowledging that the primary technological advantage of RF lies in the minaturazation of RF power electronics by the wireless power industry.
Discussion:
> To the authors’ knowledge, the specific impulse and thrust efficiency levels measured in the Phase Four RFT presented here represent the highest performance electrodeless thruster results ever demonstrated, by a significant margin. Specifically, the electrodeless RFT-X engine produced specific impulse on par with state of the art low power Hall effect thrusters, within 50% the thrust output at the same power level [17, 18]. This is as opposed to previous electrodeless thrusters that could not achieve the same order of magnitude thrust and/or specific impulse as their traditional Hall effect and gridded ion counterparts.
> The performance improvement highlights improved understanding of the thruster ion acceleration and energy transfer mechanisms, which are captured in proprietary unified design rules that extend across thruster variants.
"Get some gas, microwave it to make it really really hot, hold it in with magnets as long as possible, then when it escapes out the back it's going really fast, pushing the spacecraft forwards".