Microwave Air Plasma Thruster: Fossil Fuel-Free Jet Propulsion

Prototype Microwave Air Plasma Thruster Schematic

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

A prototype design of a plasma jet thruster can generate thrusting pressures on the same magnitude a commercial jet engine can, using only air and electricity.

Humans depend on fossil fuels as their primary energy source, especially in transportation. However, fossil fuels are both unsustainable and unsafe, serving as the largest source of greenhouse gas emissions and leading to adverse respiratory effects and devastation due to global warming.

A team of researchers at the Institute of Technological Sciences at Wuhan University has demonstrated a prototype device that uses microwave air plasmas for jet propulsion. They describe the engine in the journal AIP Advances, from AIP Publishing.

“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,” said author Jau Tang, a professor at Wuhan University. “There is no need for fossil fuel with our design, and therefore, there is no carbon emission to cause greenhouse effects and global warming.”

Beyond solid, liquid, and gas, plasma is the fourth state of matter, consisting of an aggregate of charged ions. It exists naturally in places like the sun’s surface and Earth’s lightning, but it can also be generated. The researchers created a plasma jet by compressing air into high pressures and using a microwave to ionize the pressurized air stream.

This method differs from previous attempts to create plasma jet thrusters in one key way. Other plasma jet thrusters, like NASA’s Dawn space probe, use xenon plasma, which cannot overcome the friction in Earth’s atmosphere, and are therefore not powerful enough for use in air transportation. Instead, the authors’ plasma jet thruster generates the high-temperature, high-pressure plasma in situ using only injected air and electricity.

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.

By building a large array of these thrusters with high-power microwave sources, the prototype design can be scaled up to a full-sized jet. The authors are working on improving the efficiency of the device toward this goal.

“Our results demonstrated that such a jet engine based on microwave air plasma can be a potentially viable alternative to the conventional fossil fuel jet engine,” Tang said.

Reference: “Jet propulsion by microwave air plasma in the atmosphere” by Dan Ye, Jun Li and Jau Tang, 5 May 2020, AIP Advances.
DOI: 10.1063/5.0005814

5 Comments on "Microwave Air Plasma Thruster: Fossil Fuel-Free Jet Propulsion"

  1. “Fossil Fuel-Free Jet Propulsion”

    Yeah right. We’ll have airplanes powered by 1,000 mile long extension cords? Or flying with 200 ton batteries?

  2. Well a 747 carries 161 tons of jet fuel, so yeah sure maybe.

  3. Michael De Marre | May 8, 2020 at 10:39 pm | Reply

    It sounds to me that it will make its own electricity once it’s running

  4. Chris Elliott | May 29, 2020 at 1:24 am | Reply

    Read the paper. Has this been peer-review at all?
    Interested to know how a 2.45 GHz microwave emitter is creating the plasma, as air is totally transparent to microwaves at that frequency.
    If you follow the DOI link and watch the video the description of what is occurring as ‘levitation’ is very over blown. This is not thrust, as would be useful for moving a vehicle.
    Finally the glass tube shows a glowing structure which looks like a yellow flame. If the driving force was an air plasma then the glow would be blue and transparent. Looks like incomplete combustion of an introduced hydrocarbon.
    In summary I believe this report to be pure hoax. File with cold fusion.

  5. Edward M Allen | March 13, 2021 at 2:28 pm | Reply

    The air is pressurized, and likely has a lot of moisture in it unless they ran it trough an air dryer. The dieletric effect means you get heating of the water vapor high enough to ionize along with the gases in the air. Now you have not only air, but water plasma providing thrust. You could even afterburn with water.

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