Researchers in China have demonstrated a prototype device that uses microwave air plasmas for jet propulsion, an advance that could one day replace fossil fuel combustion engines.
The team from the Institute of Technological Sciences at Wuhan University describe the engine in AIP Advances.
Waiting in the wings: How plasma could help revolutionise aircraft design
“The motivation of our work is to help solve the global warming problems owing to humans’ use of fossil fuel combustion engines to power machinery, 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.”
The researchers are said to have created a plasma jet by compressing air and using a microwave to ionise the pressurised air stream.
This method is claimed to differ 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 they team said cannot overcome the friction in Earth’s atmosphere, and are 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 1kg steel ball over a 24mm diameter quartz tube, where the high-pressure air is converted into a plasma jet by passing through a microwave ionisation 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 in a statement.
Sounds brilliant, but no mention of how much electricity is consumed and how it is created (mass, fuel source) or stored (batteries?) on board – quite fundamental
Interesting idea. What runs the power supply and air compressor? Presumably it is the air flow from this that creates the jet! Does it consume more energy than it produces (where have we seen this before)?
I doubt that this is more efficient than driving a fan directly with a electric motor. The compression as well the heating up to reach the plasma phase consumes a huge amount of energy, which most probably won’t generate that much more thrust.
This might be useful for supersonic flight, but I can’t imagine that this will be suitable for normal flying.
It seems a good idea but as the other comments state there’s no mention of where the energy to drive the system comes from.
Sounds interesting.
Can someone explain what the difference is between this and the proposed VASIMR engine?
Really interesting, If the ions are moving in a compressed jet, there shouldn’t be any reason why you couldn’t reuse the high velocity of the dense ion stream to generate power in a feedback loop to boost efficiency. In fact, if you pass the ion stream by a pickup coil, you’ll generate a Lorentz force on the coil, potentially adding to the thrust whilst generating power.
Perhaps the 1950s idea of a nuclear powered airplane might make a comeback?
There are two known ways to power air-breathing plasma jets (and potentially rockets). One, is with an on-board nuclear reactor, which has the problems of shielding, something which has never been solved due to the added weight. The other way is by beamed energy from ground stations, or eventually orbital stations, via microwaves. This capability is being currently developed. Of course, with fusion, it would be possible to do this without either of the two options mentioned, but that capability is not yet within current means.
Compressed air alone could lift a 1 kg ball ? What we need to know is the extra lift provided by the plasma.
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. That’s why this frequency is used for some WiFi routers, RADAR systems and microwave ovens. Fun fact 2.45 GHz is precisely the frequency used in microwave ovens.
If you follow the DOI link and watch the video the description of what is occurring as ‘levitation’ is very over blown. I suspect turning the ‘plasma’ off and just running the compressed air would give an identical result.
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 should be blue/white. Looks like incomplete combustion of an introduced hydrocarbon.
In summary I believe this report to be pure hoax. File with cold fusion.
https://aip.scitation.org/doi/full/10.1063/5.0005814 . And read all report sheets. “Interested to know how a 2.45 GHz microwave emitter is creating the plasma, as air is totally transparent to microwaves at that frequency”. Frequency and power are different things. You can have high frequency and low power, and you can have high frequency and high power. Plasma air has more volume than air(…) “I suspect turning the ‘plasma’ off and just running the compressed air would give an identical result.” Naive statement… So whats the point of this? Its the proof of compressed air can move things? Of course it can.
Yellow.. I suspect sodium, such as sodium hydroxide in water injected into the airstream as it goes through the microwave generator.. and this is the wrong application and incomplete as the mass that the equipment requires offsets the power generated as seen with almost all electrical propulsion systems as the load (payload) goes up.
Apply this type of principle (as a subset) to cutting something and then you are getting somewhere..