Development of a Sintered Porous Neck Filter for miniature Joule Thomson Cryo-cooler for cooling Infrared detectors

Abstract

Abstract One of the primary requirements for operation of Infrared (IR) detector systems for defence applications is the availability of a reliable miniature cryocooler. Due to a simple configuration, compact and light structure and rapid cool down characteristics, miniature Joule Thomson (JT) cryocoolers are considered ideal for IR detector systems. The need for high purity gas supply is a main concern in order to ensure long and reliable operation of Joule Thomson miniature cryocoolers. Minute solid particles are the common and problematic impurity which on being lodged in the cooler orifice hampers the cryo-cooling process of the cooler by choking which affects the operation of IR detector packaged in an Infrared detector cryochamber or dewar. The paper focuses on realization of sintered porous neck filter, the developmental aspects of the same and its characterization. In the present work a sintered porous neck filter with 5μm pore size and a filter porosity of nearly 35% was developed. The filter developed was assembled at the warm end of the cooler and the cooler assembly was integrated in the IR cryochamber for in system evaluation and confirmation of the desired quality of the developed porous filter.