Analysis of a two stage pulse tube cooler by modeling with thermoacoustic theory

A two stage pulse tube cooler operated with magnetic valves has been tested. The no-load temperature is close to 6 K, and with powers of 4 W and 15 W at the first and second stage, the respective temperatures are 20 K and about 60 K. Additionally, temperatures and pressures have been measured at different positions. This system is being analysed by calculations based on a linearized thermoacoustic theory. Reasonable agreement is obtained when some parameters are fitted. Moreover, the calculations give valuable information on volume flow, pressure drop, phase angles, energy flows, and temperatures at all positions of the system. Those results will be discussed with respect to further optimisation of such systems.