Closed cycle cryogenic fiber extrusion system

A fiber extrusion system is described that produces frozen fibers of almost any condensible gas. This extruder has the advantage of employing a closed-refrigeration system. To date, this system has produced fibers of H-2, D-2, and Ne of a diameter ranging from 100 to 130 mu m. The extrusion occurs at a specific temperature which is several degrees below the triple point of these gases. Once the fiber is extruded it can survive in vacuum for 20 min if the nozzle (extrusion) temperature is lowered to 8 K. The length of these fibers can be of the order of 1 m. D-2 fibers will be used in a staged Z-pinch experiment as a fuel for thermonuclear fusion. For this application a guiding structure is needed to position the fiber between the electrodes with millimeter precision, without significantly affecting its quality. (C) 1996 American Institute of Physics.