Use of emission spectroscopy for real-time assessment of relative wall erosion rate of BHT-200 hall thruster for various regimes of operation

Abstract

Radiation emission due to Boron atoms sputtered from the Boron-Nitride ceramic walls of a BHT-200 Hall thruster was measured as a diagnostic for real time assessment of thruster wall erosion and to determine the effects of various operation conditions on thruster lifetime. Boron neutral 249.677 and 249.773nm lines were measured using a high resolution spectrometer. Spectral measurement results and the accompanying analysis and discussion are presented in this study. From the spectral measurements it was observed that the Boron emission intensity significantly increases for increased discharge voltage pointing to a large increase in the thruster wall erosion rate. Additionally, the measurements show that for the nominal discharge voltage and the applied magnetic field intensity, there is an optimum propellant flow rate for minimum Boron emission, thus minimum wall erosion rate. The variation in the current to the magnet coils showed that the Boron emission intensity increases for increased magnetic field and the Boron emission intensity shows similar behavior to that of the Xenon single ion emission line intensity at 248.911nm. The findings of the study show that emission spectroscopy can be used in determining the optimum operational parameters for minimum wall erosion for SPT type Hall thrusters.

Ion thrusters for electric propulsion: Scientific issues developing a niche technology into a game changer

“…A major issue of spacecraft EP interaction is related to the interaction of the neutralized ion plume with parts of the thruster itself, 129,[344][345][346][347][348][349][350][351][352] other components of the spacecraft, [353][354][355] other spacecrafts in the case of debris removal employing EP for momentum transfer, 92 or with parts of the test facility in the case of terrestrial testing. 265,356 One has to distinguish between the damage induced by material sputtering by the ion beam itself and effects due to the deposition of either the propellant itself or its sputter products on surfaces of the spacecraft.…”

“…Examples of internal sputter damage are grid erosion in the case of RIT and Kaufman-type engines 345,347,348 or channel erosion in the case of Hall thrusters. 344,346,349 External erosion of other components may occur in the case of solar panels. 355 Deposition of material may occur when propellants, other than noble gases, such as iodine (which is employed as an alternative to xenon in the case of ion thrusters), or indium and cesium metal (which are employed as propellants in FEEPs) condensate on the surfaces of the spacecraft.…”

Review of Plasma-Induced Hall Thruster Erosion

“…The importance of pressure facility effects on erosion rate was recently examined by Zhang et al [53] and Ortega et al [54]. In parallel, other researchers [46,[55][56][57][58][59][60][61][62][63][64] have developed in-situ erosion rate measurement techniques, such as telemicroscopy and spectroscopy.…”

An interferometric force probe for beam diagnostics and the study of sputtering

“…Spectroscopic techniques like optical emission spectroscopy [3], laser absorption spectroscopy [4], and laser-induced fluorescence [5] are also applied, but less frequently. Recently, force measurements were performed in the beam of an industrial broad-beam ion source that is very similar to the plume of gridded ion thrusters [6].…”