A Chinese team at Wuhan University’s Institute of Technological Sciences has demonstrated a prototype of a microwave plasma thruster that can work in Earth’s atmosphere and produces thrust with an efficiency similar to the jet engines on modern aircraft. The team describes the engine in the journal AIP Advances.
Plasma thrusters are generally known for their role in spacecraft as a means of solar-electric propulsion that uses xenon plasma. However, xenon plasma is useless in the Earth’s atmosphere because accelerated xenon ions lose their thrust force to friction against the air. Instead, the prototype plasma jet thruster generates the high-pressure, high-temperature plasma using only injected electricity and air.
Jau Tang, the study’s lead author and a professor at Wuhan University, said:
The motivation of our work is to help solve the global warming problems owing to humans’ use of fossil fuel combustion engines to power machineries, such as cars and airplanes. There is no need for fossil fuel with our design, and therefore, there is no carbon emission to cause greenhouse effects and global warming.
The four states of matter include solids, liquids, gases, and plasma. Plasma consists of a cumulation of charged ions that exist naturally in places like Earth’s lightning and the sun’s surface, though humans can generate it. The team developed a plasma jet by compressing air into extreme pressures and then using a microwave to ionize the pressurized air stream.
In the laboratory, the prototype plasma jet thruster was able to lift a 1KG steel ball over a 24MM diameter quartz tube, where the high-pressure air passed through a microwave ionization chamber to convert into a plasma. To scale, the thrusting pressure is comparable to a jet engine on a commercial airplane.
The prototype device can be scaled up to a full-sized jet by building an array of thrusters with high-power microwave sources. The team’s next steps are to work on improving the device towards this goal.
Tang concluded:
Our results demonstrated that such a jet engine based on microwave air plasma could be a potentially viable alternative to the conventional fossil fuel jet engine.
This innovative plasma thruster design could contribute to the emerging field of zero-local-emissions electric aviation.
