A resonator is this week being constructed for a thermal thruster that, scaled up, could one day propel a 1,000kg (2,200lb) launch vehicle into low-Earth orbit using microwave beams.

The cylindrical resonator will focus incoming microwave energy on to an inner tube through which gaseous hydrogen flows, forming a microwave thermal rocket. Its fuel, which could be hydrogen, would be heated for thrust by directed energy from a ground station.

The rocket’s engine is effectively a large heat exchanger, transferring the microwave or possibly laser energy to the fuel. “The resonator will help us understand the process better so we can scale it up,” says California Institute of Technology aeronautics department graduate student Kevin Parkin.

Until August, Parkin’s doctoral thesis research was supported by the US Air Force Space Command.

He is in talks with the US Defense Advanced Research Projects Agency to continue the work next year.

A full-scale ground station, which would be an array of 100-200, $2 million, 1MW Gyrotrons emitting microwaves in the 100Ghz wavelength, would consume up to 500MW transmitting energy to a launch vehicle.


Source: Flight International