2 K J-T cooler for quantum detection: emphasis on the Stirling-type pulse tube pre-cooler

Abstract

Abstract Quantum detection of single photon achieves its highest sensitivity for temperature below 2 K. The cooling requirements for such application are very low, a few milliwatts for current harness heat intercept and radiation shielding. For that purpose, we are developing a compact cryocooler based on a 4He JT cooler. A high frequency pulse tube will provide the pre-cooling of two intermediate stages on the JT. The pulse tube is the key component for miniaturization and energy consumption. With low cooling power goals, a miniaturization work has been done on the pulse tube with the aim of reducing the size and power of compressor units. The pulse tube configuration is using two cold fingers, connected together by a heat intercept providing precooling for the lowest temperature stage. Cooling power at the cold tip as well as intercept heat flow have been measured. Numerical simulations have been conducted in parallel to study the impact of the size of the pulsation tube and of the regenerator on the pulse tube performances. Three cold units pulse tubes have been tested in similar conditions. Net cooling power, power at the intercept and impact of the tube and regenerator size on performances will be discussed.