A study of an air-breathing electrodeless plasma thruster discharge

Abstract

Plasma chemistry of main Earth atmospheric components in VLEOs is implemented in a hybrid 2D axisymmetric simulation code to assess the air-breathing concept in an electrodeless plasma thruster. Relevant electron-heavy species collisions for diatomic molecules, and atom associative wall recombination into molecules are included. Simulations are run by injecting 1 mg/s of Xe, N₂ and O independently for powers between 10 and 3000 W. The performances and trends of plasma response for N₂ and O are similar to Xe but displaced to higher powers. Since they have lighter elementary masses, a higher plasma density is generated and more electrons need to be heated. At optimum power, the thrust efficiency for N₂ and O surpasses that of Xe, which is caused by the excess of neutral re-ionization and the associated inelastic and wall losses. Additional simulations are run injecting 50/50 of N₂/O to study the thruster operation for propellant mixtures, and the performances are found to be linear combinations of those of each propellant in the absence of collisions between heavy species. Injection of O₂ is also studied for the impact of the possible associative recombination of O at the intake walls, and the performances are found similar to those of O due to the strong molecular dissociation inside the thruster.