More efficiency for the radiofrequency plasma space engine

November 11 () –

A Tohoku University researcher has increased the performance of a high-powered electrodeless plasma thruster, one more step to deeper explorations in space.

Electric propulsion is a technique that uses electromagnetic fields to accelerate a propeller and generate thrust that propels a spacecraft.

Several space missions have already been successfully completed using electric propulsion devices, such as cross-linked ion thrusters and Hall thrusters. Solar energy is converted into thrust energy when the propellant is ionized, that is, a plasma, and is accelerated by electromagnetic fields. Nevertheless, the electrodes required for these devices limit their useful lifeas they are exposed and damaged by the plasma, especially at a high power level.

To circumvent this, scientists have turned to electrodeless plasma thrusters. One such technology harnesses radio frequency (rf) to generate plasma. An antenna beams radio waves into a cylindrical chamber to create plasma, where a magnetic nozzle channels and accelerates the plasma to generate thrust.

These MN rf plasma thrusters, or helicon thrusters as they are sometimes known, offer simplicity, operational flexibility, and a potentially high power-thrust ratio.

But its development has been hampered by the efficiency of converting radio frequency power into thrust energy. Early experiments generated single-digit conversion rates, but the most recent studies have reached a modest result of 20%.

In a recent study published in Scientific Reports, Professor Kazunori Takahashi, from the Department of Electrical Engineering at Tohoku University, achieved a conversion efficiency of 30%.

Although mature electric propulsion devices often use xenon gas, which is expensive and difficult to supply in sufficient quantities, the current efficiency of 30% was obtained with argon propellant. This indicates that an MN rf plasma thruster would reduce the cost and resource burden of the Earth.

“The application of a cusp-type magnetic field inhibited the energy loss that usually occurs in the plasma source wall,” Takahashi said. “The breakthrough opens the door to advances in high-powered space transportation technology.”