A CRYOGENIC FIBER MAKER FOR CONTINUOUS EXTRUSION

A cryogenic fiber maker that continuously extrudes fibers is presented . The design of the fiber maker is based on the use of two cooling sta ges maintained at different temperatures. The fiber maker consists of two copper reservoirs that are connected in series and are kept at dif ferent temperatures. The first reservoir is used to liquefy the gas co ming in from an external gas line. The second reservoir is colder than the first; here, the liquid that comes from the first reservoir is fr ozen and later extruded using the pressure of the external line gas su pply. A two-stage closed-cycle refrigerator (a Gifford-McMahon cooler) , which uses helium as a working fluid, is used as a cooling system. T he frozen gas is extruded through a stainless-steel capillary nozzle w ith internal diameters between 50 and 250 mu m and a length of 2 mm. T he temperature of the two reservoirs is set independently, which permi ts the extrusion rate of the fibers to be controlled and to produce th e fibers continuously. Using this system, hydrogen, deuterium, nitroge n, and argon fibers of various diameters were extruded. (C) 1998 Ameri can Institute of Physics. [S0034-6748(98)00506-1]