Very near-field plume investigation of the D55

Abstract

The plasma properties of the very near-field (10 to 50 mm) plume of the D55 anode layer thruster (TAL) were measured as part of an effort lead by NumerEx of Albuquerque, NM to model the processes within TALs. The D55 is the 1.35 kW TAL counterpart to the SPT-100 and was made by TsNUMASH of Kaliningrad, Russia. The thruster was tested in the 6 m diameter by 9 m long vacuum chamber at (lie Plasmadynamics and Electric Propulsion Laboratory (PEPL), and the diagnostic probes were positioned using a three axis translation table system. A Faraday probe, water-cooled Hall probes, emissive probes, and Langmuir probes were used to examine the near-field plasma properties. Water-cooled Hall probes were employed to explore the effect of the closed drift current on the radial magnetic field. The change in the magnetic field due to the Hall current was found to be less than five percent over the region examined. Ion current density profiles showed that the annular beam focuses within 40 mm of the thruster exit plane. Similarly, the electron temperature and number density radial profiles showed peaks near the discharge chamber at 10 mm axially, and the peaks moved toward the axis within 40 mm. The peak electron temperature decreased with axial distance, while the number density remained approximately constant over the very near-field region.

Development of a high-speed, reciprocating electrostatic probe system for Hall thruster interrogation

“…Moreover, it is also much smaller than perturbations observed by other researchers conducting similar experiments. 13,15 For example, Hargus 13 observed discharge current perturbations of 150% and completely destroyed his probe. Upon examination of the probe following this test, there was no noticeable material ablation such as that illustrated in Fig.…”

A Hall probe diagnostic for low density plasma accelerators

“…Detailed descriptions of the plasma generated by this device and its performance can be found elsewhere. 4,[7][8][9] The primary goal of the magnetic field investigation was to establish bounds for the magnitude of the closed drift current. The azimuthal drift acts to decrease the overall radial magnetic field, and this effect will become evident when comparing the field generated by the electromagnets alone with the discharge magnetic field.…”

“…Hall-effect thrusters have electron number densities and temperatures as high as 8 ϫ10 12 cm Ϫ3 and 10 eV, respectively. 4,5 A simple experiment showed that the particle and radiative fluxes upon a 12.8 mm diam rod left in the near-field plume of the TAL were suffi-cient to heat it to greater than 200°C. Since the Hall sensor was limited to operation below 100°C, active water cooling was employed in addition to radiative and particle flux shields.…”

A Vaporizing Liquid-Metal Anode for High-Power Hall Thrusters

“…The P-values for each factor are extremely small, ranging from 5.3x 10 2 5 to 3.7x 10, 8 . Similarly to thrust, this indicates that the specific impulse saw a statistically significant change as each experimental factor was modified.…”