Thermophotovoltaic (TPV) systems are a type of energy conversion technology that generate electricity using thermal radiation. They have been explored for space applications due to their potential to efficiently convert heat from a heat source into electricity without the need for moving parts. Here's an overview of how electricity is generated in TPV systems for space applications:
Heat Source: TPV systems require a heat source to produce thermal radiation. In space applications, this heat source is typically provided by a nuclear reactor, a radioisotope heat source, or other high-temperature heat sources that can be found in spacecraft systems.
Emitter: The heat generated by the heat source is directed towards an emitter, which is designed to emit thermal radiation in the infrared spectrum. The emitter's material properties and temperature are crucial in optimizing the efficiency of the TPV system.
Photovoltaic Cell: The thermal radiation emitted by the emitter is incident upon a photovoltaic (PV) cell. The PV cell is a semiconductor device that converts photons from the thermal radiation into electricity through the photovoltaic effect.
Energy Conversion: When the infrared photons from the thermal radiation strike the PV cell, they are absorbed by the semiconductor material. This absorption generates electron-hole pairs, creating an electrical current in the PV cell.
Electrical Output: The electrical current produced by the PV cell is then collected and used as electricity to power various spacecraft systems or stored in batteries for later use.
It's worth noting that TPV systems are still under development and face several technical challenges. One of the main challenges is achieving a high conversion efficiency, as not all thermal radiation emitted by the emitter can be efficiently converted into electricity by the PV cell. Additionally, managing the heat from the high-temperature heat source and maintaining the emitter and PV cell at optimal operating temperatures are critical for achieving optimal performance.
TPV systems have the potential to provide a lightweight, reliable, and long-lasting power generation option for space missions, especially in scenarios where other power sources like solar panels may not be feasible or efficient due to limitations posed by the space environment. However, as of my last update in September 2021, TPV technology was still in the research and development phase for space applications, and it is possible that advancements have been made since then.