Internal plasma potential profiles in a laboratory-model Hall thruster

Abstract

The Plasmadynamics and Electric Propulsion Laboratory High-speed Axial Reciprocating Probe system is used in conjunction with a floating emissive probe to measure plasma potential in the discharge chamber of the P5 Hall thruster. Plasma potential measurements are made at a constant voltage, 300 V, at two different discharge current conditions: 5.4 and 10 A. The plasma potential contours for the 5.4 A case indicate that the acceleration region begins several millimeters upstream of the exit plane, extends several centimeters downstream, and is uniform across the width of the discharge chamber. The 10 A case is similar to the 5.4 A case with the exception that the acceleration region is shifted downstream on centerline. Axial electric field profiles, computed from the measured potential, show a double peak structure in the 5.4 A case, indicating a zone of ion deceleration. Perturbations to the discharge current are shown to correspond spatially with the location of the peak electric field indicating that thruster perturbations may result from a disturbance to the Hall current, as opposed to ablation of probe material. This conclusion is supported by the lack of any observable material ablation.

Particle-in-Cell Simulation of a 5 Kw Hall Thruster

“…9(a), when the Bohm diffusion was modeled, the position of the maximum electron kinetic energy was located upstream of the position of the maximum magnetic field. This observation was in accordance with the past study [18]. In Fig.…”

Effect of anode dielectric coating on Hall thruster operation

“…In spite of a number of experimental [3][4][5][6][7][8][9][10][11][12] and theoretical [13][14][15] studies of a HT internal plasma structure, the understanding of the intra-anodal and near-anode processes in HTs is still very limited. It was suggested theoretically that steady-state operation of a HT requires the presence of a negative anode fall.…”

Experimental Studies of Anode Sheath Phenomena in a Hall Thruster Discharge

“…29 was employed for measurements in the near-anode region of the 2 kW Hall thruster with clean and coated anodes. 27 The thruster has a conventional annular configuration with a channel length of 4.6 cm (which is in the 2 -8 cm range typical for HTs [11][12][13][14][15][16][17][18][19][20][21][22] ) and a channel width of 2.5 cm [ Fig The plasma potential, plasma density and electron temperature were measured at 2, 7…”

“…In spite of a number of experimental [11][12][13][14][15][16][17][18][19][20][21][22] and theoretical [23][24][25][26] studies of a Hall thruster internal plasma structure, the understanding of the anode sheath phenomena in Hall thrusters was, until recently, very limited. A more detailed review of previous works and additional motivation for studying the anode sheath phenomena in Hall thrusters can be found in Refs.…”