Development on low temperature high frequency pulse tube cooler is underway at CEA/SBT. For space applications, it is possible to use passive cooling available on numerous science mission to decrease the no load temperature and enhance the cooling power. Based on previous experiments performed with in line configurations, an integrated coaxial configuration has been built and tested. Temperatures below 15 K without load and 20 K with 300 mW load has been achieved in inertance mode. The passive cooling is simulated by a GM cooler. The influence of the heat intercept temperature on the pulse tube performance is presented. The heat to be removed at the heat intercept as function of various parameters such as heat intercept temperature and input power is discussed. Finally, a second compressor has been used to perfectly control the phase shift in the pulse tube cold finger. Inertance limitation has been observed for ultimate temperature. A temperature as low as 10.1 K has been obtained with the phase shifter compressor.