Abstract: A positive retraction mechanism for cryogenic thermal joints including deformable interfaces to separate joints which have cold welded utilizing a moveable enclosing sleeve and an actuating mechanism including the force of a compressed bellows to move a retraction flange into engagement with retraction rods which force the thermal joint apart through controlled movement of the retraction flange.

Abstract: A cryogenic system, such as a superconducting magnet assembly of magnetic resonance imaging equipment, is cooled by a refrigeration unit having a first surface refrigerated to a desired temperature. The first surface has a indentation in which an indium body is bonded to the first surface. A copper thermal conductor has a second surface on which an indenter is formed. Preferably the indenter is either a spiraling peak or an array of pyramids projecting from the second surface. A mechanism is provided to hold the thermal conductor against the indium body with the indenter penetrating the body.

Abstract: A method of igniting a deuterium-tritium ICF fuel target to obtain fuel burn in which the fuel target initially includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell. The target is permitted to free-fall through a target chamber having walls heated by successive target ignitions, so that the target is uniformly heated during free-fall to at least partially melt the frozen fuel layer and form a liquid single-phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior shell surface. The falling target is then illuminated from exteriorly of the chamber while the fuel layer is at substantially uniformly single or bi-phase so as to ignite the fuel layer and release energy therefrom.