A heat exchanger for a fast cooldown cryostat having high pressure and low pressure flow paths wherein a low pressure flow path is defined by a finely divided matrix which in turn defines a plurality of flow paths and said high pressure flow path is disposed in heat exchange relationshp to said matr...http://www.google.com.au/patents/US4781033?utm_source=gb-gplus-sharePatent US4781033 - Heat exchanger for a fast cooldown cryostat
