Plasma Acceleration with Microwaves near Cyclotron Resonance

Abstract

Effect of cyclotron resonance on the microwave detection properties of a glow discharge plasma Am.centimeters even at frequencies as high as 100 GHz. In practice, the attenuation of such waves in samples of ordinary dimensions is probably governed by surface irregularities. It is only when the lOOO-GHz region is reached that the anharmonic processes discussed here would form an important attenuation mechanism at low temperatures (in that case well below SOCK).At higher temperatures the anharmonic processes will be more important. In quartz (e = 600 o K, M v 2 / K = SOOOOoK, vI=6XlO 5 cm/sec) and at 114 GHz one would expect a to be about 1XlO-3 cm-I at T=O and about 1 X 10-1 at lOoK. Ilukor and Jacobsen 2 found an anharmonic attenuation about a factor ten larger at that temperature and frequency. The discrepancy may well be due to collinear prOCesses of the type L~ L+ L, which we have not considered here, but which playa large role at lower frequencies. 6 • 7 These processes can be important when KT> nw, though they should lead to an attenuation proportional to the first power of frequency, and the extra attenuation found by Ilukor and Jacobson is considerably higher than would be indicated by an extrapolation from the results of Thaxter and Tannenwald l at 70 GHz. Clearly one needs not only a better theory, particularly calculations for the awkward region nw~KT, but also more experimental data.Acceleration of a microwave-energized plasma by expansion in a diverging magnetic field is studied. Results of a theoretical collisionless particle analysis are reviewed. An experimental accelerator is described and its pertinent conditions are considered. Measurements of plasma beam shape and potential are compared with the theoretical predictions. The conclusions are that, while some experimental characteristics (beam shape and potential profile) agree with theory, col)isions in the experimental device prevent it from attaining operating conditions predicted by collisionless theory.

Direct Thrust Measurement of an Electron Cyclotron Resonance Plasma Thruster

“…Stallard and Hooper, also studied these technologies and developed a prototype based on a bi-helical antenna [7,8]. The interest into these technologies was hampered by the low efficiency of the microwave generators available at the time, and the poor vacuum conditions of the experiments (often much larger than 5 …”

“…ECR plasma thrusters have been studied since the 60s [5]. In the middle of the 90s, Sercel performed a study on an ECR engine where the microwaves are launched in the plasma source from a cylindrical waveguide [6].…”

“…Experimental parametric studies have shown that the thruster performances are very sensitive to the operating conditions; the mass-flow rate, the injected power and the magnetic field magnitude have a significant effect on the ion energy and the mass efficiency. It has also been shown that the ion energy to electron temperature ratio, e i T E / , is constant for a given magnetic field magnitude (about [4][5]. This enables the use, in certain conditions, of a polytropic expansion law to model electron cooling and ion acceleration in the magnetic nozzle [16,17].…”

CubeSat Lunar Positioning System Enabled by Novel On-Board Electric Propulsion

“…The ECRA is an electrode-less electric propulsion device that was first investigated for possible spacecraft propulsion in the 1960s [15], [16]. Back then the main obstacle to its development were the size and (in)efficiency of the contemporary microwave power generators compared to DC power supplies.…”

“…This undoubtedly prompted the rise of other electric propulsion devices, such as ion or hall thrusters. However, the underlying electron-resonance mechanism provides an efficient wave-plasma coupling [15]. Furthermore the device produces a neutral plume, foregoing the need for a neutralizer.…”