Stable and self-adaptive performance of mechanically pumped CO(2) two-phase loops for AMS-02 tracker thermal control in vacuum

A mechanically pumped CO(2) two-phase loop cooling system was developed for the temperature control of the silicon tracker of AMS-02, a cosmic particle detector to work in the International Space Station. The cooling system (called TTCS, or Tracker Thermal Control System), consists of two evaporators in parallel to collect heat from the tracker's front-end electronics, two radiators in parallel to emit the heat into space, and a centrifugal pump that circulates the CO(2) fluid that carries the heat to the radiators, and an accumulator that controls the pressure, and thus the temperature of the evaporators. Thermal vacuum tests were performed to check and qualify the system operation in simulated space thermal environment. In this paper, we reported the test results which show that the Trcs exhibited excellent temperature control ability, including temperature homogeneity and stability, and self-adaptive ability to the various external heat flux to the radiators. (C) 2011 Elsevier Ltd. All rights reserved.