Self consistent kinetic simulations of SPT and HEMP thrusters including the near-field plume region

The Particle-in-Cell (PIC) method was used to study two different ion thruster concepts - Stationary Plasma Thrusters (SPT) and High Efficiency Multistage Plasma Thrusters (HEMP-T), in particular the plasma properties in the discharge chamber due to the different magnetic field configurations. Special attention was paid to the simulation of plasma particle fluxes on the thrusters channel surfaces. In both cases, PIC proved itself as a powerful tool, delivering important insight into the basic physics of the different thruster concepts. The simulations demonstrated that the new HEMP thruster concept allows for a high thermal efficiency due to both minimal energy dissipation and high acceleration efficiency. In the HEMP thruster the plasma contact to the wall is limited only to very small areas of the magnetic field cusps, which results in much smaller ion energy flux to the thruster channel surface as compared to SPT. The erosion yields for dielectric discharge channel walls of SPT and HEMP thrusters were calculated with the binary collision code SDTrimSP. For SPT, an erosion rate on the level of 1 mm of sputtered material per hour was observed. For HEMP, thruster simulations have shown that there is no erosion inside the dielectric discharge channel.Comment: 14 pages, 11 figures This work was presented at 21st International Conference on Numerical Simulation of Plasmas (ICNSP'09

Particle modeling of radial electron dynamics in a controlled discharge of a Hall thruster

Special issue on plasma-surface InteractionsAn improved radial particle-in-cell model of an annular Hall effect thruster discharge with secondary-electron emission from the walls and a radial magnetic field is presented. New algorithms are implemented: first, to adjust the mean neutral density to the desired mean plasma density; second, to avoid the refreshing of axially accelerated particles; and third, to correctly weigh low-density populations (such as secondary electrons). The high-energy tails of the velocity distribution functions of primary and secondary electrons from each wall are largely depleted, leading to temperature anisotropies for each species. The secondary-electron populations are found to be partially recollected by the walls and partially transferred to the primary population. The replenishment ratio of the primary high-energy tail is determined based on the sheath potential fall. Significant asymmetries at the inner and outer walls are found for the collected currents, the mean impact energy, and the wall and sheath potentials. Radial profiles in the plasma bulk are asymmetric too, due to a combination of the geometric expansion, the magnetic mirror effect, and the centrifugal force (emanating from the E x B drift). The temperature anisotropy and non-uniformity, and the centrifugal force modify the classical Boltzmann relation on electrons along the magnetic lines.The work at UC3M was supported by the CHEOPS project, funded by the European Union’s Horizon 2020 Research and Innovation Programme, under Grant Agreement 730135. Additional support came from Spain’s National Research and Development Plan (Project ESP2016-75887). F T was sup-ported by the Apulia Space Project (grant PON03PE_00067_6)

Plasma propulsion simulation using particles

This perspective paper deals with an overview of particle-in-cell / Monte Carlo collision models applied to different plasma-propulsion configurations and scenarios, from electrostatic (E x B and pulsed arc) devices to electromagnetic (RF inductive, helicon, electron cyclotron resonance) thrusters, with an emphasis on plasma plumes and their interaction with the satellite. The most important elements related to the modeling of plasma-wall interaction are also presented. Finally, the paper reports new progress in the particle-in-cell computational methodology, in particular regarding accelerating computational techniques for multi-dimensional simulations and plasma chemistry Monte Carlo modules for molecular and alternative propellan

Parametric study of the radial plasma-wall interaction in a Hall thruster

An investigation on the influence of relevant parameters on an annular Hall effect thruster plasma discharge is performed using a radial particle-in-cell simulation code with secondary electron emission from the walls and prescribed axial electric and radial magnetic fields. A simulation with true-secondary electrons only is taken as reference. First, the near-wall conductivity effects on the magnetized secondary electrons are illustrated by doubling the , allowing a further code validation. Second, when secondary backscattered electrons are included, the enhanced secondary emission yields lower sheath potential drops and primary electron temperature. Moreover, the dominant backscattered electrons increase the average secondary electrons emission energy, greatly affecting its temperature anisotropy ratio and increasing the replenishment level of the wall collectable tails of the primary electrons velocity distribution function. Third, the effect of the true-secondary electrons emission energy on the potential profile is shown to be negligible, the latter being mainly set by the dominant magnetic mirror effect. Finally, a planar case featuring symmetric plasma profiles permits to confirm the validity of the large cylindrical asymmetries present in the reference case, induced by the combined effects of the geometric expansion, the magnetic mirror and the centrifugal force (due to the drift). A smaller deviation of the primary electron momentum equation from the Boltzmann relation along the magnetic lines is still found in the planar case, induced by the parallel temperature non-uniformity.The UC3M researchers have been supported by the PROMETEO-CM project, Grant number Y2018/NMT-4750 (Comunidad de Madrid/FEDER/FSE). Additional funding for A Domínguez-Vázquez came from Project ESP2016-75887 (Spain's National Research and Development Plan - MINECO/FEDER) F Taccogna has been supported by the italian Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR) under the CLOSE project (grant ARS01_00141)

One Dimensional Hybrid-Vlasov Simulation of a Hall Thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97103/1/AIAA2012-4313.pd