Thrust measurements and plume diagnostics in magnetically confined laser ablation propulsion

Résumé fourni par la source

Abstract Laser ablation propulsion utilizes the momentum generated by an expanding plume produced by a focused laser beam to impart thrust on an object. This method offers a propellant-agnostic system with applications ranging from orbital debris removal to asteroid deflection for planetary defense. This study examines the effect of axial magnetic fields in a diverging nozzle configuration on thrust performance and efficiency. A hanging pendulum thrust stand is used to perform direct impulse measurements of aluminum targets ablated with a nanosecond pulsed laser under peak magnetic fields of up to 0.4400 Tesla. Triple Langmuir probe measurements temporally resolve electron temperature and density. ICCD imaging captures plasma evolution, and a Faraday probe characterizes plume divergence. Confocal microscopy of ablation craters provides mass removal estimates. Aluminum targets demonstrated thrust enhancements of up to 16.9% and specific impulse improvements of up to 18.7% under magnetic confinement. However, increasing field strengths enhanced plasma shielding and suppressed mass removal, resulting in decreased thrust. The results reveal two competing mechanisms: plume focusing, which reduces divergence losses at lower field strengths, and plasma shielding, which suppresses ablation at higher field strengths. These findings indicate an optimum field strength exists where focusing benefits are maximized before shielding penalties are significant.

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