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This paper assesses the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 % (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems.

A technique is discussed for generating diagnostic information from the vibration signature of machinery in the high-frequency range (up to 100 kHz). The signal generation mechanism is discussed, as well as the diagnostically significant characteristics of the data and a method of extracting this information. Two specific cases are presented utilizing the techniques to illustrate its suitability for many of the common problems encountered in machinery.