Before they're strapped onto rockets for a mission to Mars, ion engines, like NASA's VASIMR project need to be tested—here at the STG-ET chamber at the German Aerospace Agency (DLR), one of the most advanced vacuum chambers on the planet.
Vacuum chambers allow researchers to recreate the conditions of outer space and range in size from those that fit on a desktop to units like the STG-ET chamber with 362 cubic meters of interior volume.
The $US4 million euro STG-ET chamber (German for Propulsion Beam Simulation Facility - Electric Thrusters) opened for operation on the 27th of October 2011. Primarily for use in testing ion engines and their effects on satellites, the 12-meter long, five-meter tall tube is equipped with a helium-based cryogenic pump to lower the interior temperature just a few degrees above absolute zero.
This minimal -268 degree Celsius temperature is necessary due to the nature of ion engine testing. These engines generate thrust by ionizing Xenon gas and accelerating it through an electric field. Because the ion beam also damages the sensitive electronics on-board satellites—especially solar cells—space agencies need to opbtain precise measurements of the beam characteristics. The cryogenically-frozen tube prevent ionised gases from reflecting off its walls, skewing test results, and instead freeze solid on contact.
"With its exceptionally realistic conditions, this facility stands apart from existing European facilities. The background vacuum that we can create here is unique," explained Andreas Dillmann, Head of the DLR Institute of Aerodynamics and Flow Technology.