Replacement for RTGs in space exploration?

[John Jacobus <crispy_bird@YAHOO.COM>]

>From another list server.



---------

PHYSICS NEWS UPDATE

The American Institute of Physics Bulletin of Physics

News

Number 695 August 5, 2004  by Phillip F. Schewe, Ben

Stein

. . .

                	

ACOUSTICALLY POWERED DEEP-SPACE ELECTRIC GENERATOR. 

Space is a new frontier for an acoustical version of a

19th-century mechanical device. For future deep space

missions to the outer planets and beyond, space

agencies would like their probes to have a lighter,

smaller, and more efficient source of electricity.

With this need in mind, a Los Alamos-Northrop Grumman

team (Scott Backhaus, backhaus@lanl.gov) has built a

device that uses sound waves to produce 60 watts of

electricity.  The core of this device is called TASHE,

short for "thermoacoustic-Stirling heat engine." An

acoustical version of a 19th-century engine design

(named after Scottish minister Robert Stirling, who

invented it), the TASHE is a looped contraption made

from pipes and heat-exchanging devices.  In the TASHE

system, intense, spontaneously generated sound waves

(in the place of mechanical pistons in the

19th-century design) shuttle parcels of helium gas

between a cold end and hot end.  The hot and cold end

temperatures are generated by connecting the engine to

a high-temperature heat source and an

ambient-temperature heat sink through the heat

exchangers.  Thermally driven expansion and

contraction of the gas, in concert with pressure

oscillations (induced by the temperature difference),

intensify the power of the initial sound waves which

become strong enough to drive a piston connected to

the device.  The motion of the piston vibrates a coil

of copper wire that produces electricity as it moves

relative to a permanent magnet.  The acoustic device

has 18% efficiency, compared to 7% for

thermoelectrics, the current electrical-generation

technology in spacecrafts in which a temperature

difference across a material is converted into

electric power. (In both designs, small amounts of

radioactive material provide the high-temperature heat

needed for operation.)  The new device can produce a

projected 8.1 watts of electricity per kilogram, as

opposed to 5.2 watts/kg for thermoelectrics.  These

properties allow for a potential increase in the size

and power of science instruments in future space

probes. This is the latest application of the TASHE,

which is also being developed to liquefy remote

reserves of natural gas for a more economical

transport of this fossil fuel resource to market than

previously possible.  (Backhaus, Tward, and Petach,

Applied Physics Letters, 9 August 2004)



*********** 



=====

+++++++++++++++++++

"We Americans have no commission from God to police the world"

Benjamin Harrison



-- John

John Jacobus, MS

Certified Health Physicist

e-mail:  crispy_bird@yahoo.com





		

__________________________________

Do you Yahoo!?

Yahoo! Mail - 50x more storage than other providers!

http://promotions.yahoo.com/new_mail

************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/