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This paper presents the design, testing and analysis of the 5kW ammonia Capillary Pumped Two Phase Loop (CPL), developed in co-operation between MATRA MARCONI SPACE (MMS) and the French Space Agency (CNES). The ammonia CPL breadboard was designed to transport a 5 kW heat load over 5 meters. It consisted of: 5 parallel evaporators and isolators, 4 parallel condensers with an additional sub-cooler, a reservoir, to control the loop saturation temperature, two adiabatic pipes, one for the liquid line and one for the vapour line the testing instrumentation including thermocouples and absolute and differential pressure transducers.

Cooling detectors down to 0.1K will be of great importance for future far infra red and submillimeter space telescopes during the next few years. This objective can be reached using a Stirling Cryocooler and a Joule Thomson (JT) expansion stage to precool to 4K. The low temperatures are then obtained by an open cycle dilution refrigerator circulating 3He and 4He. This system does not need any cryogenic reservoir and can be launched at room temperature. In this paper, we present the characteristics and performances of the two parts of the refrigerator measured separately, showing the feasibility of such a system. Expected performances of the complete system are a base temperature of 100mK with 100nW heat load and a life time of 5 years with a reasonable gas storage weight (20-50 kg).

This paper presents the benefit for receiver thermal performance of installing heat pipes on top of the INTELSAT V - FM 15 antenna panel. The FM 15 spacecraft launched in January 1989 is identical in all respects to the FM 13 spacecraft launched in May 1988, except for the addition of three interconnection heat pipes on the external surface of the antenna panel. So this flight experiment is unique, because it allows a direct in-flight comparison between two identical spacecraft, one with, and one without heat pipes. Detailed thermal mathematical models have been developed to correlate the anticipated results obtained from INTELSAT V - FM 13 and FM 15 with those obtained from flight telemetry and to verify the level of heat transfer coefficients of the heat pipes.