Plasma ‘ring’ sets the stage for further research
In the 1980s, a novelty product that introduced people to a basic form of plasma technology soared in popularity. The plasma globe utilized a mixture of gases that discharged plasma filaments in a glass globe. The touch of a finger provided a large receptor producing a place for energy to flow and a brilliant, little self-contained light show.
In the larger picture of space, reactions in the sun create energy-emitting plasma, also known as the fourth state of matter, and back on earth, potential applications of plasma technology have resulted, most popularly, in flat-screen televisions. Devising plasma technologies that can further benefit consumers is a topic of research in research labs around the world.
Until now high-density plasmas have only been generated in controlled environments, but researchers in the University of Missouri College of Engineering’s Electrical and Computer Engineering Department have devised a system that creates a toroidal- (or ring-) shaped plasma emission. But unlike previous research, this plasma generates in open atmosphere.
“Scientists have investigated the generation of long-lived plasma in open air without a vacuum or outside magnetic field for years, but have failed previously to produce a self -sustaining plasma,” Randy Curry, Logan Distinguished Professor of Electrical Engineering, said.
Curry’s team in the Center for Physical and Power Electronics has been working on open-air plasmas for the last few years. Funded by the Office of Naval Research, the plasma rings projected from Curry’s system don’t emit radiation and do not present a danger to humans who might be exposed to them.
The system uses pulsed-power energy made from a DC power supply that charges capacitors and discharges the energy quickly. It explodes a copper wire that is housed behind a biased-metal, mesh screen — or accelerator grid — held between two pieces of Plexiglas. The wire is vaporized, and the resulting plasma results in a self-propagating ring of plasma lasting “tens of milliseconds.”
“We’ve been able to develop an approach that forms a stable plasma ring in open atmospheric conditions,” Curry said.
The ring-shaped blast of plasma projects up to 24 inches.
Curry said the open-air occurrence is revolutionary and made possible because a self-magnetic field that is present.
The discovery came as a surprise after Curry suggested to Adam Lodes, a former graduate student, that he make a number of key modifications to the system.
“It was serendipitous,” Curry said. “He came in here and said, ‘I don’t quite know what I have here.’’
Upon inspection, Curry verified the results of a toroidal-shaped plasma, which was later confirmed by a leading plasma researcher from Princeton University.
Curry added this research is part of the most basic science of plasmas, and that theoretically, a larger machine would create a larger ring that could potentially travel a much longer distance. Further funding, he stressed, is important because it could lead to a smaller device that would create an output equal to a larger machine.
“We were funded by the ONR on a basic science research program to research plasmas,” he said.
“In the future, we will investigate the use of this plasma for the generation and storage of energy,” he said.
It may be three-to-five years before this technology could be used to significantly advance power and energy storage, Curry said. Until then, he stressed the need for funding of this kind of research.
“We have a world-class team here, and without that funding, that team will evaporate,” Curry said. “Without that funding, I don’t see us competing.”
Watch a slow-motion capture video of the exploding plasma ring below, courtesy of the MU News Bureau.