Numerical simulation of hydrogen arcjet thruster using coupled sheath model

In the present work, a complete 2D chemical and thermal non-equilibrium numerical model coupled with a relatively simple sheath model is developed for hydrogen arcjet thruster. Conduction heat transfer in the anode wall is also included in the model. The operating voltages predicted by the model are compared with those in the literature and are found to be in close agreement. Power distributions for the various operating conditions are obtained, anode radiation loss primarily determines the thruster efficiency. Higher thruster efficiency was found to be associated with longer arc length. At cathode ion diffusion contribution dominates except at low input current where thermo-field electron current is dominant.

The underexposed effect of elastic electron collisions in dusty plasmas

Dusty plasmas comprise a complex mixture of neutrals, electrons, ions and dust grains, which are found throughout the universe and in many technologies. The complexity resides in the chemical and charging processes involving dust grains and plasma species, both of which impact the collective plasma behavior. For decades, the orbital-motion-limited theory is used to describe the plasma charging of dust grains, in which the electron current is considered collisionless. Here we show that the electron (momentum transfer) collision frequency exceeds the electron plasma frequency in a powder-forming plasma. This indicates that the electron current is no longer collisionless, and the orbital-motion-limited theory may need corrections to account for elastic electron collisions. This implication is especially relevant for higher gas pressure, lower plasma density, and larger dust grain size and density.