2025 Theses Doctoral

Orbital Analysis, Microwave Power Beaming and Semiconductor Material Damage Assessment for Space-Based-Solar Systems

Peters, Anthony R.

Technological advancements must keep pace with the earth’s rising demand for energy, while minimizing the carbon footprint on earth. One such option is using space based solar (SBS) energy harvesting and radiofrequency (RF) microwave power beaming. In 1968, Dr. Peter Glaser published "Power from the Sun: Its Future", qualitatively illustrating that SBS can be, at some time in the future, a solution to solar intermittency on earth. However, the high cost of this option and the drastically reduced cost of terrestrial solar energy combined in leaving this concept as aspirational as a trip to other planets. This technology is currently being explored under a renewed prism, to address not only terrestrial photovoltaic (PV) intermittency but also in high latitude remote areas and to transmit power to spacecraft in various orbits. A catalyst of this renewed interest is the promise of reusable launch vehicles (RLV) which can drastically reduce the cost of bringing SBS components to orbit.

This dissertation offers an overview of the current status on SBS research and space industry capabilities. It includes a discussion of reliance of SBS initiatives on (RLV) to place SBS spacecraft in various designated orbits, as well as the technological, economic, and operational challenges associated with power beaming to earth and other spacecraft. Moreover, this dissertation presents a novel investigation of the pros and cons for SBS deployment in different orbits coupled with semiconductor material damage analysis associated with each orbital environment.

Power beaming will be accomplished via microwave emissions, and transmit power to both terrestrial ground stations, as well as other space vehicles (SV) in various earth orbits. This dissertation includes the mechanics of energy transferred from point to point, as well a detailed analysis of the medium (i.e., atmospheric scattering due to gaseous attenuation of the wireless energy) in which the energy must pass, with a comprehensive explanation of the associated losses therein. Power beaming is the” The limitations of wireless power transfer (WPT) are explored, where power beaming “efficient point-to-point transfer of electrical energy across free space by a directive electromagnetic beam” utilizes directive propagated waves that exclude waveform that can be used in destructive applications. In this dissertation, the use of power beaming is suggested primarily for use in delivering power to remote terrestrial areas such as forward operating bases (FOB), industrial sites, and unmanned vehicles (both on ground and in the air).. The use of microwave emissions is the focus for this dissertation as this mode offers the ideal solution in terms of efficiency for transmitting large amounts of power over long distances. A conceptual framework and mathematical model are developed to quantify the system limitations for power beaming based on current technology.

Radiation impacts on space-based systems operating on various orbits were evaluated. The software utilized for this dissertation include: (1) COMSOL Multiphysics v2.1, where Monte Carlo simulations were run for charged particle tracing and particle matter interactions, which were additionally tailored for different materials (i.e., GaAs, SiC). (2) Matlab was used for developing unique simulations to complete numerous orbital analysis, transmission of RF energy through the atmosphere, and lunar trajectories; Matlab was also used in the materials assessment of GaAs/InP PV cells, using the (3) MC-SCREAM software developed by the Naval Research Laboratory. This software was modified and expanded to use the specific PV cells for space vehicles, various types of cover glass and dielectric coatings, and a new radiation library database for radiation spectra in various orbits using (4) SPENVIS. Calculations for various material non-ionizing energy loss (NIEL) profiles were completed in (5) SR-NIEL to input into MC-SCREAM, further expanding the software to meet the analysis needs in this dissertation. Specifically, satellite operations in LEO, MEO, and Geosynchronous Orbit (GEO) were analyzed. Special focus is given on quantifying the effect of high energy particle space radiation on materials used for critical power components, where component fault can lead to total mission failure.

Methods, using multiple computational platforms for the quantification of NIEL and displacement damage dose (DDD), are used to assess semiconductor damage as a function of orbital altitude. Detailed simulations were conducted for Gallium Arsenide Indium Phosphide (GaAs/InP) solar cells with various cover glass thicknesses. It was assessed that radiation exposure due to high energy protons at 10000 km is more prevalent than 20000 km orbits and that electrons are the major electronics damage culprits. For MEO at 10000 km, MEO at 20000 km, and GEO at 36000 km, we determined 1-year maximum power (Pmax) losses due to protons to be 23%, 8%, and 1%, and losses due to electrons at 11%, 14% and 10%. Total combined spectra Pmax losses for those altitudes are 25%, 16%, and 10%, respectively. The results of the simulations were verified with previous limited scope damage analysis of satellites operating in LEO, and the survivability of GaAs cells was compared with that of Si cells. The intended spacecraft mission will often dictate the orbit in which it operates, with particular attention to the tradeoffs between operational requirements (i.e., time on top overhead of the receiver site influenced by orbital period) and orbital considerations (i.e., radiation impacts, thermal ranges, altitude deconfliction with other SVs, space debris deconfliction).. There is also a cost evaluation to consider for each orbit, specifically for the launch vehicle (LV).

This dissertation identified and assessed system efficiencies, and the orbital analysis required for SBS power beaming to remote terrestrial areas and to other spacecraft from SBS systems operating in LEO, MEO and GEO. Specific scenarios are presented to demonstrate simulation capabilities using Matlab/Simulink which provide orbit visualization, control of classical orbital elements (COEs) to determine power beaming overhead time to remote locations and other satellites, as well as eclipse cycles and solar capture forecasts. Other simulation results to support SBS operations include earth space propagation and transmission losses for desired RF microwave power beaming wavelengths. The various orbits presented as candidates for power beaming satellites are additionally presented with the associated radiation spectra for trapped protons and electrons. Radiation spectra data collection methodology is also presented, and was used for determination of radiation shielding materials, satellite survivability, and longevity for a specified mission duration. From our analysis, we identified the SBS orbit requirements for continuous space-to-earth power beaming using criteria such as overhead time, earth coverage and RF spot size, solar capture, and power delivered at the receiver site. 10000 km MEO circular orbits with 55-degree inclination are potential candidates for SBS satellites, with overhead time for a single satellite forecasted at 28%, covering 30% of earth, while optimizing solar capture at 97%. Technology improvements can increase predicted power transmission efficiencies by 5-10% through RF beam and phase focusing.

This research stems from the Air Force Research Laboratory’s (AFRL) Space Solar Power Incremental Demonstrations and Research (SSPIDR) initiative, which includes the power beaming demonstration payload known as Space Solar Power Radio Frequency Integrated Transmission Experiment (SSPRITE).