Laser Ablation Propulsion of Asteroids with a Sub-Nanosecond Pulsed Laser

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dc.contributor.advisorSedwick, Raymond Jen_US
dc.contributor.authorSloane, Joshuaen_US
dc.contributor.departmentAerospace Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2019-06-19T05:37:58Z
dc.date.available2019-06-19T05:37:58Z
dc.date.issued2019en_US
dc.description.abstractWith ablative laser propulsion, a laser is fired at a solid material. This material is converted to plasma and ejected from the material, generating thrust. This technology can be used to deflect an asteroid off of an Earth-impacting trajectory. Since the asteroid itself is used as the propellant, no additional propellant is needed for the deflection maneuver. Although laser propulsion has been proposed as a promising technology for asteroid mitigation in the literature, there has been relatively little experimental research on this application, specifically on ablation using pulsed lasers. In this thesis, ablative laser propulsion of asteroid analog materials using a pulsed laser is studied. A 1064 nm laser is used, with a 0.7 ns pulse width, 827 μJ per pulse, 40 kHz pulse repetition frequency, and 33 W average power. A time-of-flight mass spectrometer is used to characterize the plasma plume resulting from ablation of pyroxene rock. A 2D distribution of the ions is found as a function of speed and mass to charge ratio. From this, the specific impulse of the positive ions is found. The force over 500 ms of ablation is measured directly using a load cell. Force measurements are conducted on aluminum, pyroxene, and high-fidelity simulants for CM, CR, and CI meteorites. The momentum coupling coefficient for the asteroid analogs was found to be several times greater than for aluminum. These samples are also weighed before and after ablation to determine the mass removal rate. The measured momentum coupling coefficient and mass removal rate are used to calculate the laser ablation efficiency and overall specific impulse of the ablation plume. As expected, the overall specific impulse is significantly lower than the specific impulse associated with the high-energy ions. The overall specific impulse of the meteorite simulants is even lower than for pyroxene, likely due to slow-moving large particles. Ablative laser propulsion was compared to a Hall thruster as an example electric propulsion technology. For a total thrust time greater than six months, laser ablation traded favorably, benefiting from not needing propellant aboard the spacecraft for the deflection maneuver.en_US
dc.identifierhttps://doi.org/10.13016/cvh9-gmfq
dc.identifier.urihttp://hdl.handle.net/1903/21920
dc.language.isoenen_US
dc.subject.pqcontrolledAerospace engineeringen_US
dc.subject.pquncontrolledAsteroid mitigationen_US
dc.subject.pquncontrolledForce measurementsen_US
dc.subject.pquncontrolledLaser ablationen_US
dc.subject.pquncontrolledTime-of-flight mass spectrometryen_US
dc.titleLaser Ablation Propulsion of Asteroids with a Sub-Nanosecond Pulsed Laseren_US
dc.typeDissertationen_US

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