Abstract: A liquid nitrogen capillary tube heat exchanger comprises a vertical array of alternating vaporization chambers and pressure control chambers connected together in series. The vaporization chambers each have a plurality of capillary tubes mounted in exterior loops along the exterior of the chamber in communication with liquid nitrogen in the chamber. The capillary tubes provide a contolled rate of vaporization of the liquid nitrogen and increased exterior surface area to facilitate refrigeration. The pressure control chambers are filled with copper filings and a dessicant.