| The pulse tube cryocooler represents a relatively recent development in cryogenic technology. It has the potential for high reliability due to the elimination of all moving parts at the low temperature end. The purpose of this study is to obtain better understanding of the refrigeration mechanism and the capability of the pulse tube cryocooler.;In the next step, under the low amplitude limit, a consistent simplified model for the pulse tube cryocooler system is developed. It includes a single partial differential equation for pressure, coupled with an ordinary differential equation for temperature. This simplified problem can easily be solved in Fourier space using the Runge-Kutta method. Different configurations of pulse tube cryocoolers are studied using this model, including the orifice, double-inlet and inertance pulse tube cryocoolers.;A pulse tube prototype has been designed, built and tuned to meet the cooling need of SKA radio telescope. It achieved a low temperature of 50 K with normal thermal-insulation condition, and a coefficient-of-performance of 1/35 at 80K, which is comparable with Stirling cryocooler.;The regenerator in the pulse tube cryocooler is subjected to reciprocating viscous flow, which usually results in two insidious effects, namely significant; pressure drop and phase shift. These viscous effects, together with the impedances of other components, ultimately determine how large the enthalpy and work fluxes along the regenerator and how efficient the system will be. To correctly formulate the relationship locally, a model is proposed based on a multiple length scale technique. The key scaling assumption, consistent with a drop to leading order in the pressure amplitude across the regenerator, requires the ratio of the mesh size over the regenerator length to be of the same order as the Mach number squared, divided by the Reynolds number. Under this assumption, and assuming the regenerator is close to isothermal, a complete asymptotically consistent solution to the regenerator problem is formulated. |
