Making waves in space
A University of California scientist working at Los Alamos National Laboratory and researchers from Northrop Grumman Space Technology have developed a novel travelling-wave thermoacoustic electric generator for generating electrical power aboard spacecraft.
The travelling-wave system, described by Scott Backhaus and his Northrop colleagues, Emanuel Tward and Mike Petach in a recent issue of the journal Applied Physics Letters, is similar to current thermoelectric generators but is more than twice as efficient.
Current thermoelectric devices used for the generation of electricity aboard spacecraft convert just 7% of a heat source energy into electricity, while the travelling-wave engine converts 18% of the heat source energy into electricity.
The engine works by sending helium gas through a stack of 322 stainless-steel wire-mesh discs called a regenerator. The regenerator is connected to a heat source and a heat sink that causes the helium to expand and contract. This expansion and contraction creates powerful sound waves in the travelling-wave engine to drive the piston of a linear alternator that generates electricity.
Since the only moving component in the device besides the helium gas itself is an ambient temperature piston, the researchers say that the device possesses the kind of high-reliability needed for deep space probes.
The complete article in Applied Physics Letters can be seen <link>here=http://content.aip.org/APPLAB/v85/i6/1085_1.html</link>.