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Mechanism Study On Air-breathing Laser Propulsion

Posted on:2007-09-30Degree:MasterType:Thesis
Country:ChinaCandidate:B J DiFull Text:PDF
GTID:2178360242462079Subject:Physical Electronics
Abstract/Summary:PDF Full Text Request
Laser propulsion, which works on the force generated during the interaction between high-power laser and propellant, is a new concept technique for propulsion. The technique is considered to be a potential process in aeronautics and astronautics such as launching micro satellite into Low Earth space,Orbital Maneuvering and light pilotless aircraft. In laser propulsion, there are two modes, which are the air-breathing mode and the ablative mode. The substantial difference of these two modes is that some propellants pre-taken by the craft will be consumed for the ablative mode while there is no mass losing for the other one. In the thesis, laser propulsion was studied theoretically and experimentally.Firstly, theoretical analysis and calculations for laser propulsion were performed. The result shows that by combining two propulsion modes, micro satellite can be launched into Low Earth space using a finite laser power. For instance, for 100kW laser power, by using following launching schedule, lightcraft can be launched from ground to near space: first using air-breathing mode, the 5kg lightcraft can be lifted to 39.7km in 133.1s, then, using the ablative mode the lightcraft can be lifted to 49.482km in 200s.Secondly, experiments of air-breathing mode were carried out using self-developed UV-preionized TEA CO2 laser. The influences of laser parameters and the lightcraft structure on laser propulsion were investigated. Some useful results were obtained.During the wire-guided vertical flight experiment, impulse coupling coefficient 390 N/MW was obtained, which is much higher than the existed data obtained using electron-beam sustained pulse CO2 laser. This may be caused by the difference of the lightcraft structure and the laser pulse shape.Air disturbance after the interaction of pulsed laser radiation with lightcraft wa also studied. It was found that the focal length of the parabolic lightcraft had significant role on the air-disturbance. Two shock waves were detected for longer focal length, but only one shock wave was detected for short focal length. Furthermore, it was also found that air-disturbance existed much longer time than that of the laser pulse. The spectrum of the plasma was detected using monochromator and photodiode. It was found that the delay time of the line spectrum decay detected by the monochromator was much shorter than that of the plasma decay detected by photodiode, suggesting that the radiation time detected by photodiode is not considered as the plasma decay time. It is also found that the plasma decay time is longer than the pulse duration and the time evolvement process of line spectrum relates to the pulse shape.
Keywords/Search Tags:Laser propulsion, Air-breathing mode, Momentum coupling coefficient, Plasma
PDF Full Text Request
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