Analysis of a cusped helicon plasma thruster discharge

Abstract

Experiments and simulations are used to analyze a compact helicon plasma thruster with a cusp in its internal magnetic field. The former rely on a compensated Langmuir probe and a Faraday cup, while the latter employ a hybrid PIC/fluid transport model combined with a frequency-domain electromagnetic field model. Measurements serve to tune the anomalous transport parameters of the model and overall show the same trends as the numerical results, including a secondary peak of electron temperature downstream in the magnetic nozzle, where electron cyclotron resonance conditions for the 13.56 MHz excitation frequency are met. The cusp plays a central role in determining the plasma losses to the walls and the profile of electron temperature, which in turn defines the excitation and ionization losses. While losses to the rear wall are reduced, losses to the lateral wall are increased, which, together with the low production efficiency, limit the performance of the device.

Effects of cavity resonance and antenna resonance on mode transitions in helicon plasma

“…The radial profile of plasma density is closely related to the magnetic field B 0 since the axial magnetic field will restrain the radial transport of electrons [33,34] which creates the helicon plasma by collisional ionization. Meanwhile, the radial profile of plasma density is significantly related to the power deposition determined by the profile of helicon wave fields with local electron kinetics [10,20,35].…”

“…Meanwhile, the radial profile of plasma density is significantly related to the power deposition determined by the profile of helicon wave fields with local electron kinetics [10,20,35]. Thus, the changed radial profile of plasma density might be related to the variations of plasma power deposition and the transport dynamics feature with the changed B 0 [10,33,34]. Noticeably, the radial integral of the plasma density in figure 7(b) seems unchanged, and this will be discussed in section 4.3.3.…”

Analysis of Wave Propagation with Different Magnetic Configurations in Helicon Plasmas

“…It is found that the diamagnetic effect plays a significant role in the thruster generation. In addition, a hybrid PIC/fluid transport model combined with a frequency-domain electromagnetic field model was introduced by Jiménez [36] to analyze the helicon discharge with a cusped magnetic configuration in helicon thrusters. It is concluded that the cusp plays a central role in determining the plasma losses to the walls.…”

Thrust measurements of a waveguide electron cyclotron resonance thruster

“…However, a considerable fraction of power is lost on plasma-wall recombination, excitation losses, and divergence losses. 13,14 Two main strategies for coupling the microwave power into the plasma have been explored, differing in the way MW is injected and propagated into the plasma chamber: the circular waveguide and the coaxial ECRTs. The first method consists of MW injected in the TE 11 (transverse electric) mode from a cylindrical waveguide through a dielectric window; the second method instead brings MW power through a coaxial cable and relies on the presence of an additional central conductor to obtain a TEM propagation mode.…”