The Hampson-type miniature Joule-Thomson (J-T) cryocooler is widely used in electronic cooling. We develop the geometry model of the Hampson-type cryocooler to better Understand the double helical tube-and-fin heat exchanger. The steady-state governing equations of the cryogen, helical tube and fins, and shield are solved numerically and yield good agreements with experiment data. The conventional way of simulating a Hampson-type J-T cryocooler, which is accompanied by a host of empirical correction factors, especially vis-A-vis the heat exchanger geometry could now be superseded. The effort and time spent in designing a Hampson-type J-T crycooler could be greatly reduced. (c) 2005 Elsevier Ltd. All rights reserved.