Anode geometry influence on LaB6 cathode discharge characteristics

Abstract

The characterization of an electric propulsion device cathode is performed in the so-called diode configuration with an external anode. The anode acts as a physical boundary for the cathode plasma discharge; therefore, it influences cathode operation and performances. In this study, four different anodes—namely, a disk, a plate, a long cylinder, and a short cylinder—have been used with a flat disk LaB6 emitter 5 A-class cathode to examine the anode geometry impact on cathode discharge properties. Current–voltage curves, discharge oscillations, electron parameters, and ion velocities have been measured for currents in the 2 A to 12 A range and xenon mass flow rates varied from 0.4 mg/s to 1 mg/s with a fixed cathode-to-anode distance. The set of results clearly supports the fact that the anode geometry strongly influences the cathode characteristics both at the macroscopic and the microscopic scale.

Ionization instability and turbulence in the plume of sub-ampere hollow cathodes with applied magnetic field

“…On top of that, a denser plume plasma or with a high enough electron temperature could lead to coherent instabilities with large amplitude that can be observed in an increase in anode current oscillations [5]. The anode geometry and location as well as operational parameters have a great impact on the plasma dynamics, affecting the neutral and electron densities, electron temperature, potential distribution and electric field [3,42,46]. Based on the previous studies for a cylindrical anode, a strong magnetic field at the emitter location and plume field lines intersection the anode induces larger oscillations in the anode current with higher B.…”

“…During the developmental stages, the cathodes are usually tested in the so called diode mode with an electron collector which acts as the anode in a Hall thruster. Such electron collectors are also called anodes and can be made of graphite, stainless steel, or refractory metals and shaped as disk plates, hollow cylinders, or even conical geometries [3].…”

Discharge and plasma plume characterization of a 100 A-class LaB6 hollow cathode

“…The plume mode is therefore unfavorable as it has negative implications on thruster stability and operational life. A general and simple picture of cathode mode and mode transition cannot be established as many parameters are involved like the flow rate, the gas nature, the current density, the cathode design, the anode geometry [27] and the cathode-to-anode gap [20]. The mode cannot be determined in a reliable manner from a sole visual inspection of the plume, see Fig.…”

Analysis of anode surface roughness influence on heaterless hollow cathode discharge

“…Although a few studies have previously documented the impact of experimental design and test equipment on hollow cathode discharge characteristics, including the effects of anode position [30,37,38] and geometry [39][40][41][42] on cathode discharge profiles and plumes. Given the under-explored theme of anode surface roughness and its influence on hollow cathode discharge, this study will investigate the impact of the surface roughness of cylinder and planar anode on cathode operation characteristics, aiming to lay a foundational basis for standardizing future hollow cathode testing.…”