Plasma Experiments: Bio-decontamination to Satellite Propulsion

Prof. Alex Shashurin’s research group has recently received a patent on a novel method for generating a plasma jet. Instead of a complex pulsed power source, the jet requires only the application of a constant voltage. The applied voltage causes the formation of a plasma streamer as seen in the photo. After a short time, the streamer goes out, but the gas recovers and another streamer appears. Depending on geometry and flowrate, this leads to auto-oscillation at a repetition rate up to 20 kHz.

So, what’s this good for? Many things. One of the most promising applications lies in bio-decontamination. In food processing and medical applications, there is an urgent need to kill harmful bacteria. Describing a commercial freeze-drying operation, Shashurin says it “[uses] some nasty stuff, like peroxide …, and it’s complicated and expensive.”

As a better alternative, Shashurin’s team is looking at mounting plasma jets on the walls of a freeze-drying device, to efficiently create “reactive species which are very effective” for killing bacteria.

A microwave horn next to the plasma jet for microwave scattering measurements. Another emphasis of Prof. Shashurin’s group is plasma diagnostics, ways to address the difficult problem of measuring the properties that characterize a cold plasma. One unique diagnostic method that his team has developed is a microwave scattering system that measures the absolute electron number density in a cold plasma. “Pretty much, there is no other way to measure plasma density in these atmospheric pressure plasmas,” says Shashurin.