<p>A detailed experimental investigation into the performance of a low-power Hall effect thruster (HET), Simplified CAMILA, operating on both atomic (Xe, Kr, Ar) and molecular (CO<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(_2\)</EquationSource> </InlineEquation>, N<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(_2\)</EquationSource> </InlineEquation>) propellants is performed. The study measures thrust, specific impulse, and internal efficiencies across a range of discharge voltages (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\sim\)</EquationSource> </InlineEquation>75–450 V), input powers (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\sim\)</EquationSource> </InlineEquation>75–450 W), and magnetic field strengths (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\sim\)</EquationSource> </InlineEquation>118–293 G). Xenon consistently delivers the highest anode efficiency (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\eta _A\)</EquationSource> </InlineEquation>) performance (<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\eta _A\)</EquationSource> </InlineEquation> = 48.74%, 400 W), followed by krypton (<InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\eta _A\)</EquationSource> </InlineEquation> = 33.01%, 450 W), argon (<InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\eta _A\)</EquationSource> </InlineEquation> = 22.72%, 450 W), CO<InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(_2\)</EquationSource> </InlineEquation> (<InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\eta _A\)</EquationSource> </InlineEquation> = 11.68%, 450 W), and N<InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(_2\)</EquationSource> </InlineEquation> (<InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(\eta _A\)</EquationSource> </InlineEquation> = 7.35%, 400 W). Molecular propellants exhibit significantly lower efficiencies and narrower regions of operational stability, and thus require higher volumetric mass flow rates and magnetic field strengths for stable operation. These observations highlight the engineering challenges of maintaining discharge stability with molecular gases, particularly at lower voltages where mass utilization efficiency sharply declines. Mass and current utilization efficiencies improve with power for all propellants—particularly for molecular ones—though beam efficiency remains relatively constant. We employ a previously developed mass utilization efficiency model to accurately predict experimental results for all propellants within the margin of error, with argon exhibiting the largest deviation. Increasing magnetic field strength initially enhances anode efficiency (requiring <InlineEquation ID="IEq14"> <EquationSource Format="TEX">\(\sim\)</EquationSource> </InlineEquation>1·48x stronger fields for molecular gases versus Xe/Kr), but eventually reduces ion beam current, especially in lighter molecular gases, potentially because of increased ion trajectory divergence due to smaller ion cyclotron radii relative to heavier xenon. These findings underscore the challenges and potential of using molecular propellants in low-power HETs. While inert gases remain superior in performance, molecular propellants can sustain operation under optimized conditions. Further thruster design and operational refinements are needed to improve the viability of molecular propellants for future space missions.</p>

Performance comparison and analysis of low-power hall thruster operation on atomic and molecular propellants

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2026年7月9日

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Joseph A. Moskovitz,
Maxim Rubanovich,
William P. Brabston,
Dan Lev,
Mitchell L. R. Walker,
Vladimir Balabanov

摘要

A detailed experimental investigation into the performance of a low-power Hall effect thruster (HET), Simplified CAMILA, operating on both atomic (Xe, Kr, Ar) and molecular (CO \(_2\) , N \(_2\) ) propellants is performed. The study measures thrust, specific impulse, and internal efficiencies across a range of discharge voltages ( \(\sim\) 75–450 V), input powers ( \(\sim\) 75–450 W), and magnetic field strengths ( \(\sim\) 118–293 G). Xenon consistently delivers the highest anode efficiency ( \(\eta _A\) ) performance ( \(\eta _A\) = 48.74%, 400 W), followed by krypton ( \(\eta _A\) = 33.01%, 450 W), argon ( \(\eta _A\) = 22.72%, 450 W), CO \(_2\) ( \(\eta _A\) = 11.68%, 450 W), and N \(_2\) ( \(\eta _A\) = 7.35%, 400 W). Molecular propellants exhibit significantly lower efficiencies and narrower regions of operational stability, and thus require higher volumetric mass flow rates and magnetic field strengths for stable operation. These observations highlight the engineering challenges of maintaining discharge stability with molecular gases, particularly at lower voltages where mass utilization efficiency sharply declines. Mass and current utilization efficiencies improve with power for all propellants—particularly for molecular ones—though beam efficiency remains relatively constant. We employ a previously developed mass utilization efficiency model to accurately predict experimental results for all propellants within the margin of error, with argon exhibiting the largest deviation. Increasing magnetic field strength initially enhances anode efficiency (requiring \(\sim\) 1·48x stronger fields for molecular gases versus Xe/Kr), but eventually reduces ion beam current, especially in lighter molecular gases, potentially because of increased ion trajectory divergence due to smaller ion cyclotron radii relative to heavier xenon. These findings underscore the challenges and potential of using molecular propellants in low-power HETs. While inert gases remain superior in performance, molecular propellants can sustain operation under optimized conditions. Further thruster design and operational refinements are needed to improve the viability of molecular propellants for future space missions.