Project Title:

Miniature, Cryogenic Turboalternator

92-1-09.17-3800                                                   NAS05-32413
Miniature, Cryogenic Turboalternator
Creare, Inc.
P.O. Box 71
Hanover, NH  03755
Herbert Sixsmith                                     (603-643-3800)

Abstract:

     The company will develop a miniature, cryogenic
turboalternator that will be an enabling technology for future
low-power, vibration-free, space cryocoolers. The concept uses an
alternator rotor incorporating a high-energy permanent magnet of
uniquely simple construction and a novel ironless stator to absorb
power from the cryogenic expansion turbine in a reverse Brayton
cryocooler. Its advantage over more conventional turboexpanders is
its avoidance of the parasitic heat leak from the room-temperature
brake impeller typically used to absorb power from the turbine.
Although this heat leak is of minimal importance in conventional
reverse-Brayton cryocoolers designed for relatively high cooling
loads, it is a major power penalty in the low-power instrument
coolers that NASA needs for upcoming scientific space missions. By
avoiding this heat leak, the turboalternator will enable
vibration-free Brayton cycle machines to provide the same low-
power advantage to these missions as the vibration-prone Stirling
cycle machines currently in use.

Potential Commercial Application:

Potential Commercial Applications:  The result of this development
will be a technology for miniature, high-speed electrical machines
which offers both high reliability and high electrical efficiency
with potential uses in specialty high-speed, low-power miniature
motors for medical applications.

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