Engineers Create Miniature Plasma Source for Thrusters

The Boise State engineers have created a miniature inductively coupled plasma source that could be used for ion thrusters where the propulsive force is generated by electricity rather than combustion.

In physics and chemistry, plasma is a state of matter similar to gas where a portion of the particles are ionized. The new system is a result of research on electric propulsion in low-temperature, co-fired ceramic (LTCC) materials. The engineers designed and tested a system that provides high density plasma by using the gas argon as a propellant and injecting it into a thrust chamber to move small objects like a satellite.

“Overall, electric thrusters are more efficient in propellant usage and that allows the devices to operate for longer periods of time without the need to refuel,” said study coauthor Don Plumlee, assistant professor of mechanical and biomedical engineering. “A plasma thruster provides more thrust for the mass of propellant being ejected compared to traditional chemical thrusters and it provides more efficient performance at the small thruster sizes we are targeting.”

The miniature plasma source was created out of a material that allows the integration of additional thruster elements, including propellant delivery into a single device. The concept is based on the miniaturization of an electric thruster, using ceramic materials to integrate fluidics and electronics. The researchers then tested the system over different frequencies and argon pressures. The system performed well at frequencies from 400 MHz to 1000 MHz and a resonant frequency near 920 MHz.

“Our inductively coupled plasma source also is embedded inside the ceramic substrate, which protects it from back-bombardment of the plasma ions that could potentially erode the antenna,” said study coauthor Jim Browning, associate professor of electrical engineering and computer science. “These devices are really the first step in developing a smaller electrostatic thruster in ceramic materials.”

The design and testing of the plasma source is outlined in a paper that appears online in the journal IEEE Transactions in Plasma Science.

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