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ELFIE - Laser induced ablation propulsion efficiency in the FS-NS regime for space propulsion and space clean debris (S. Boyer)

In the application form Spring 2017- Spring 2018, we submitted our proposal dealing with the ‘Investigation of laser ablation propulsion efficiency in the FS-NS regime for space application’ (proposal reference 16-TWF6). It is a three-years project. The present application is to plan the year 3 project works. However, the second year experiment weeks are planned in February 2018. Concern is on the Low-Earth Orbit (LEO) environment. The Low-Earth Orbit (LEO) environment is becoming congested with space debris due to the frequency of object launches. Collisional cascades instability is threatening, as cataloged events in which a debris collision terminated an active satellite. The main urgency is to mitigate future risks. While improved debris tracking and orbit prediction can temporarily improve threat avoidance via maneuvering, effective debris-clearing strategies will be necessary. However, it will take a decade to implement an effective debris removal system.

The proposed solutions are Absorbing or changing orbits of debris and/or Laser interaction. Less difficult to implement and costly, Laser interaction is a promising solution. As a matter of fact, the ablation impulse and efficiency can be optimized for each type of target material, and removes nm of material per pulse. In addition, all improvements of knowledge and developments performed on laser ablation propulsion of debris could serve for new concepts of space propulsion. With the development of laser technologies, this topic is nowadays a growing concern for all international space agencies. Depending on the target material nature, studies on laser irradiation parameters are showing that shorter wavelength and pulse length could lead to a maximized momentum coupling coefficient Cm to produce an optimum mechanical impulse coupling, and an improved impulse coupling coefficient.

In January 2017, experiments were performed on ELFIE facility (400fs, 80ps, 1053nm) to implement several diagnostics and validate the methodology with the pendulum allowing estimating Cm. Innovative diagnostics (PDV, angle deviation and absorption measurements) were coupled. Besides, in the operating range of pulse durations, results give a world record of momentum (800 N/MW with POM) opening new perspectives for future applications (2 articles submitted JAP/AA), EUCASS2017/HPLA2018 conferences). Clearly, we propose to emphasize these promising works. The set-up will be improved for Cm measurements (PDV will be upgraded, absorption measurements renew and shadowgraphy imaging added). However, we propose to extend measurements towards materials representative of spatial structures (Polymer, Silicium, CFRP), spanning shorter wavelength (2w, contrary to initial program 3w will not be possible on Elfie Facility) and durations of 300fs, 1-80ps and 600ps. Proposed experiments should provide new data that bracket the desired 100ps pulsewidth. Besides, results will be compared with simulations which first results obtained on Esther code are very promising. Finally, these works clearly established a new French community involved in international (Phipps, DLR, PRC CNRS with Russia for experiment in UV under submission) and industrial collaborations (CNES, Thales).

ELFIE - S50-51/2018