Laser Thermal Propulsion Utilizing Solar Thermal Conponents

Ground based laser power beaming system (1-10 MW) can be effectively utilized in the near future as a primary component of a Laser Thermal Propulsion (LTP) system for an orbital transfer vehicle. A hybrid propulsion system is proposed which includes the components of a Solar Thermal Propulsion (STP) system. There is a high degree of commonality between the hardware, configuration, function, and materials design of an STP and LTP system. Specific Impulse (Isp's) on the order of 1200 seconds with reasonable thrust levels can be achieved with LTP utilizing smaller optics and similar absorber designs of STP. Previous research with interference-based techniques, specifically holographic concentrators, can become practical with LTP. Holography enables the concentrator designed an additional degree of design freedom by allowing arbitrary choice of the ratio between angles of incidence and reflection. LTP advantages over STP include increased energy capture because of a higher energy density than the solar disk, higher energy concentration due to the coherent light and smaller optics as a result of an intense transmission beam. The Phase I effort will demonstrate feasibility of a deployable laser concentrator for LTP using a hologram as the reflective element.