Radio frequency is no longer just for connecting ground control to Major Tom
Radio frequency waves power Ad Astra’s VASIMR VX-200 plasma rocket engine.
An Atlantic company that specializes in manufacturing broadcast radio frequency (RF) amplifier technologies is applying its sound wave expertise to develop generators for a plasma propulsion rocket engine.
This may seem like a galactic leap for Nautel, a 40-year-old company with an international reputation for its high power solid-state radio broadcast transmitters, but it’s not. Nautel is applying robust R&D capabilities to expand its technology to diversify into non-communication applications, and this led to a partnership with Webster, Tex.-based Ad Astra Rocket Co. to build RF generators that power a Variable Specific Impulse Magnetoplasma Rocket (VASIMR VX-200) concept. This pre-warp speed propulsion, invented by Dr. Franklin Chang Diaz, founder of Ad Astra, would cut a lot of time off a typical space jaunt.
The technology, in development since 1979, would conceivably shorten a trip to Mars from up to two years (using existing rocket engine technology that costs millions of dollars) to about 40 days.
Electric rocket engine technologies supply about 10 kilowatts of power and currently available generators are large, primitive and impractical systems for space applications.
Ad Astra needed a small, light power generator capable of 200 kilowatts to power its plasma technology.
“They needed a device that simply didn’t exist,” says Tim Hardy, Nautel’s head of engineering. “First they needed the fundamental technology to power the engine and then they needed to take that technology and put it in a space environment.”
Nautel develops radio transmitters that drive big antennas by amplifying small radio signals to a much higher power, so it applied the same expertise to develop two generators—one that is 50 kilowatts and another that’s 180 kilowatts.
“The technology is very much the same,” says Hardy. “In the radio business we would put information on the signal. But in the generator application it’s just a continuous signal with no information.”
Traditional generators are typically installed in 1.8- by 1.5-metre racks and, depending on the power demand, there could be several of them. Nautel’s power units are the size of a golf bag.
The technology uses radio waves from the generator to heat argon gas.
“If you put enough energy into it [gas], the electrons separate away from the nuclei of the atoms and start to float around,” says Hardy. “As soon as that happens the gas becomes plasma.”