A schematic diagram of a prototype microwave air plasma thruster and the images of the bright plasma jet at different microwave powers. This device consists of a microwave power supply, an air compressor, a compressed microwave waveguide, and a flame ignitor. (Credit Jau Tang and Jun Li)

Researchers demonstrated a prototype device that uses microwave air plasmas for jet propulsion instead of fossil fuel. The plasma jet was created by compressing air into high pressures and using a microwave to ionize the pressurized air stream.

The prototype plasma jet device can lift a 1-kilogram steel ball over a 24-millimeter diameter quartz tube, where the high pressure air is converted into a plasma jet by passing through a microwave ionization chamber. To scale, the corresponding thrusting pressure is comparable to a commercial airplane jet engine.

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