Dynamic Response Of Hign-enery Pulses Laser-driven Centimetre-scale Debris In Near-earth Orbit

With the rapid increase of space objects in the near-Earth orbit,small-sized space debris around 1-10 cm already poses a serious threat to space activities.In order to reduce the potential harm to space assets,active removal of small-sized space debris in the near-Earth orbit by spacebased pulses laser has become a hot research topic in the aerospace fields.In this thesis,the main research content is focused on the space-based pulses laser-driven deorbit for centimeter-scale debris,and the results can provide guidance for engineering application.The main work and results are given,as follows:Firstly,the physical changes and energy transformation process of the debris driven by pulses laser are analyzed,and the deorbit process of the debris with velocity increment driven is explored.By analyzing the coupling mechanism of impulse coupling coefficient,pulse width,wavelength,laser energy per pulse and repetition frequency,a general model of space debris gaining velocity increment under the action of laser per pulse is established.Based on the orbital dynamics theory,the change of each orbital parameter after the debris obtaining the velocity increment is discussed,and the active deorbit process of the debris is also designed.Secondly,a multi-physical coupling model of the debris driven by nanosecond pulses laser is established,and the propagation rules of plasma expansion plumes with action time is analyzed.At the same time,the effects of laser power on plasma plumes,temperatures and pressures are investigated,and the interaction mechanism of plasma plumes distribution with the laser incidence angles is further explored,which lays a foundation for exploring dynamic deorbit process.Finally,the velocity increment model of different shape debris is established,and the validity of the model is also verified by comparison calculation.As a result,the dynamic model of spacebased pulses laser driving the debris is constructed.By numerical simulations,the evolutionary rules of the debris deorbit under different laser parameters and orbital parameters are mastered initially.The results show that the absorption of laser energy on the debris surface is improved,and the velocity of plasma expansion plumes is also generated by effectively increasing the pulses laser power.However,the energy conversion is reduced due to plasma shielding effect.As a result,the plasma expansion plumes are distributed symmetrically along the normal line of the irradiation direction for different laser incidence angles.The deorbit efficiency is very excellent when the laser station has the same inclination as the debris orbit,and the greater the difference of the two orbital inclinations,the more significant the decline of the deorbit efficiency.When perigee angle and right ascension of ascending node(RAAN)are change in a small range,the effect of debris deorbit is not affected obviously.The greater the single-pulse laser flux,the greater the velocity increment obtained by the debris.Finally,the number of pulses laser required for achieving debris deorbit is reduced,and the operation times of actively deorbit is decreased too.The repetition frequency of pulses laser is inversely proportional to the action time of debris deorbit.Hence,the increase of repetition frequency can greatly shorten the time of debris deorbit,and the increase of impulse coupling coefficient is also helpful to shorten the time of debris deorbit.By analyzing an example of collision-threatening space debris approaching a space station,the debris is effectively removed after three laser irradiation.Namely,the perigee altitude of the debris is dropped to 287.961km,245.027km and 199.915km by the action of 1238,541 and 607 pulses laser.