Parametric investigation of miniaturized cylindrical and annular Hall thrusters

Abstract

Conventional annular Hall thrusters become inefficient when scaled to low power. An alternative approach, a 2.6-cm miniaturized cylindrical Hall thruster with a cusp-type magnetic field distribution, was developed and studied. Its performance was compared to that of a conventional annular thruster of the same dimensions. The cylindrical thruster exhibits discharge characteristics similar to those of the annular thruster, but it has a much higher propellant ionization efficiency. Significantly, a large fraction of multicharged xenon ions might be present in the outgoing ion flux generated by the cylindrical thruster. The operation of the cylindrical thruster is quieter than that of the annular thruster. The characteristic peak in the discharge current fluctuation spectrum at 50-60 kHz appears to be due to ionization instabilities. In the power range 50-300 W, the cylindrical and annular thrusters have comparable efficiencies (15-32%) and thrusts (2.5-12 mN). For the annular configuration, a voltage less than 200 V was not sufficient to sustain the discharge at low propellant flow rates. The cylindrical thruster can operate at voltages lower than 200V, which suggests that a cylindrical thruster can be designed to operate at even smaller power. * Electronic mail: asmirnov@pppl.gov 2

Transition in electron transport in a cylindrical Hall thruster

“…1) has a 2.6 cm channel diameter and a 2.3 cm channel V with typical discharge currents in the range I d ∼ 0.5-0.7 A. Details of the design and operation have been described elsewhere 13 . Plasma density n is typically ∼ 3 × 10 11 cm −3 and electron temperature T e is typically 15 eV 14 .…”

Cathode Effects in Cylindrical Hall Thrusters

“…In the present study, the thruster was operated in the "direct" configuration: currents in the front and back coils are co-directed, resulting in an enhanced axial magnetic field [6].…”

Cathode effects in cylindrical Hall thrusters

“…The cylindrical Hall thruster (CHT) concept features a reduced surface-to-volume ratio in comparison to conventional annular Hall thrusters [3][4][5], making it potentially more attractive for miniaturization. Other features include quiet operation [3,4,6], high ionization efficiency [3,4,7], and a magnetic topology which may reduce channel erosion [5]. These features lead to efficiencies at low power comparable to the state-of-the-art annular Hall thrusters of commensurate size [6].…”

“…Other features include quiet operation [3,4,6], high ionization efficiency [3,4,7], and a magnetic topology which may reduce channel erosion [5]. These features lead to efficiencies at low power comparable to the state-of-the-art annular Hall thrusters of commensurate size [6]. However, a main shortcoming to the CHT design is the significantly larger divergence of the plasma plume [3].…”