No abstract

A numerical study of the effectiveness of phase change material (PCM) used on FORMOSAT-7 at the preliminary design phase is presented in this study. N-eicosane is used as the PCM for its melting temperature. To compare the performance of PCM, different messes of PCM are applied for high-power-dissipating component with short-duty-cycle. The results show that PCM can improve the thermal stability of component by not only moderating peak temperature for worst hot case but also preventing sudden temperature decrease when the power mode of component changed. However, mass addition of PCM reduces the duration of the maximum temperature and the minimum temperature due to the better thermal conductivity of solid phase. Therefore, an optimization of mass is suggested for the application of PCM.

We developed an X-ray detector using 36 arrays, each consisting of a 64-pixellated yttrium oxyorthosilicate (YSO) scintillation crystal and a 64-channel multi-anode photomultiplier tube. The X-ray detector was designed to detect X-rays with energies lower than 10 keV, primarily with the aim of localizing gamma-ray bursts (GRBs). YSO crystals have no intrinsic background, which is advantageous for increasing low-energy sensitivity. The fabricated detector was integrated into UBAT, the payload of the Ultra-Fast Flash Observatory (UFFO)/Lomonosov for GRB observation. The UFFO was successfully operated in space in a low-Earth orbit. In this paper, we present the responses of the X-ray detector of the UBAT engineering model identical to the flight model, using 241Am and 55Fe radioactive sources and an Amptek X-ray tube. We found that the X-ray detector can measure energies lower than 5 keV. As such, we expect YSO crystals to be good candidates for the X-ray detector materials for future GRB missions.