A traveling-wave engine to power deep space travel

[David Farber <dave () farber net>]

Begin forwarded message:

From: Kurt Albershardt <kurt () nv net>
Date: October 4, 2004 11:54:28 AM EDT
To: dave () farber net
Subject: A traveling-wave engine to power deep space travel

LOS ALAMOS, N.M., Sept. 16, 2004  -- A University of California 
scientist working at Los Alamos National Laboratory and researchers 
from Northrop Grumman Space Technology have developed a novel method 
for generating electrical power for deep-space travel using sound 
waves. The traveling-wave thermoacoustic electric generator has the 
potential to power space probes to the furthest reaches of the 
Universe.

In research reported in a recent issue of the journal Applied Physics 
Letters, Laboratory scientist Scott Backhaus and his Northrop Grumman 
colleagues, Emanuel Tward and Mike Petach, describe the design of a 
thermoacoustic system for the generation of electricity aboard 
spacecraft. The traveling-wave engine/linear alternator system is 
similar to the current thermoelectric generators in that it uses heat 
from the decay of a radioactive fuel to generate electricity, but is 
more than twice as efficient.

The new design is an improvement over current thermoelectric devices 
used for the generation of electricity aboard spacecraft. Such devices 
convert only 7 percent of the heat source energy into electricity. The 
traveling-wave engine converts 18 percent of the heat source energy 
into electricity. Since the only moving component in the device besides 
the helium gas itself is an ambient temperature piston, the device 
possesses the kind of high-reliability required of deep space probes.

The traveling-wave engine is a modern-day adaptation of the 19th 
century thermodynamic invention of Robert Stirling -- the Stirling 
engine -- which is similar to a steam engine, but uses heated air 
instead of steam to drive a piston. The traveling-wave 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 much 
the same way that lightning in the atmosphere causes the thermal 
expansion that produces thunder. These oscillating sound waves in the 
traveling-wave engine drive the piston of a linear alternator that 
generates electricity.
NASA funded the traveling-wave thermoacoustic electric generator 
research.

Los Alamos National Laboratory is operated by the University of 
California for the National Nuclear Security Administration (NNSA) of 
the U.S. Department of Energy and works in partnership with NNSA's 
Sandia and Lawrence Livermore national laboratories to support NNSA in 
its mission.

Los Alamos enhances global security by ensuring the safety and 
reliability of the U.S. nuclear deterrent, developing technologies to 
reduce threats from weapons of mass destruction, and solving problems 
related to defense, energy, environment, infrastructure, health and 
national security concerns.

<http://www.lanl.gov/worldview/news/releases/archive/04-078.shtml>







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