Abstract: A chuck assembly for gripping and rotating an optical fiber has a chuck body including a bearing and a journal fitted rotatably in the bearing and defining a bore for receiving the optical fiber with a clearance fit. Water is supplied to the clearance between the optical fiber and the journal and is frozen in situ, thereby securing the optical fiber against movement relative to the journal.

Abstract: A displacer assembly for use with a thermal regenerative machine has a housing configured to receive a displacer therein. The displacer has a drive area formed by a rod portion of the displacer that extends through a hole in the housing to form a clearance seal therebetween. The housing and displacer form a sub-assembly that can be pre-assembled to provide a clearance seal prior to assembly with a linear drive motor. Another feature is provided by a fluid flow path extending centrally of the displacer rod, and in part along an outer peripheral surface of the rod adjacent a heat rejection region of the housing. Heat transference there along provides for a more efficient stirling thermodynamic cycle in response thereto.