| In this dissertation, the thermal control system (TCS) of the electronic system of the alpha magnetic spectrometer (AMS) has been under investigation. The regularity of on-orbit operation of the TCS was investigated, the impact of the peculiar manoeuvres of the International Space Station (ISS) on the TCS was analysed, the temperature warnings caused by thermal environmental factors were researched, and corresponding thermal-control suggestions based on adjusting thermal environment of the AMS were proposed.In the beginning of this dissertation, the background, aims, significance and obtained physics results were introduced. Then the thermal environment on the ISS and the thermal loads of the AMS itself were introduced. Based on the thermal requirement of the electronics, the scheme of the TCS for the AMS electronics was introduced. Different from the "completely wrapped" approach for the thermal control of past spacecraft, the AMS thermal control design adopts material with large heat capacity to survive the periodically varying thermal environment. The on-orbit operation of the TCS shows that the electronics were successfully activated, the temperature curve in start-up procedure confirms to the simulation result; the temperature of all electronics was above the low survival limit in power outage, and was below the high survival limit in worst hot case, the temperature variation in a single orbit period is in allowed range. Long-time flight data manifests the correctness of the thought of TCS design, the effectiveness of the TCS.In the monitoring after the AMS started to work on the ISS, the AMS thermal group noticed that the temperature of the AMS components was affected by the beta angle (β, the angle between the ISS orbital plane and the solar vector), and presents regular variation. Due to too many of the temperature sensors (over 1100 sensors), too large amount of temperature data (temperature readout once in a minute), and the temperature variation in single orbits,8 sensors on the main radiators of the AMS and the temperature data collected in 3 years (June1,2011 to May 31,2014) were selected, algorithm mean temperature of the sensors in one orbit was calculated to represent the temperature level, and then the temperature variation regularity following β was obtained, the regularity was described with fitted mathematical equations. This regularity presents the specific β intervals at which the main radiators are in hot or cold cases, also presents the β interval at which temperature anomalies such as rapid temperature drop\rise occur, the reason of both were also analysed. By calculating the standard deviation of the temperatures in one orbit, the temperature-amplitude regularity following βwas also obtained. Bicubic spline interpolation is adopted to create the temperature field of radiators at different β, the temperature fields show that the temperature on the entire main radiators follows the regularity of orbit-average temperature with β change. Some heaters can be activated in cold case, which gives transparent heating effect in cold area, the thermal control is effective. The investigations based on actual flight data provide references for the thermal control of the AMS in long-time (about 20 years) on-orbit operation.Besides nominal operation, there are some peculiar manoeuvres executed on the ISS for different missions, mainly there are locking solar arrays, temporarily changing the flying attitude and adjusting the position of the ISS starboard radiator. Locking solar arrays is the most frequently occurred peculiar manoeuvre, generally brings temperature drop on the main radiators. Because the peculiar manoeuvres are complicated in most cases,47 times cases in which only locking solar array occurred, and 4 sensors on the WAKE radiator were selected for analysing the impact of locking solar arrays. The temperature drop within two orbits after locking solar arrays was statistically analysed. The analysis shows that the impact of locking the solar arrays on the WAKE radiator regularly varies following β. The temperature drop is greater if β is smaller, one exception is that locking solar arrays at extreme positive β also can cause great temperature drop, which even can activate the thermostatically controlled PDS heaters. Adjusting the flying attitude generally won’t bring significant temperature change on the AMS. Rotating pitch angle of the ISS by 90° is the most frequent attitude adjustment whose influence on the AMS is limited. Rotating Yaw angle of the ISS by 180° can cause the local temperature of the AMS similar to that at opposite β. In some complicated attitude adjustment such as adjusting both Yaw angle and Pitch angle, the influence could be evident. In a sideward flying attitude (rotating Yaw angle of the ISS by -90°) when β≈51°, the WAKE radiator was constantly illuminated for about 24 hours, which is the worst hot case the WAKE radiator had ever experienced, the temperature of the electronics on the WAKE radiator was below high warning limit, meanwhile the RAM radiator was in cold case that it was in shadow constantly, the temperature of the electronics on the RAM radiator was above the low warning limit. Adjusting the position of the ISS starboard radiator (defined as the y angle) can affect the temperature of port side and the main WAKE radiator of the AMS, because the ISS starboard radiator panel can reflect solar radiant heat to the AMS. By calculating the relationship between the y angle and the radiant heat reflected from the radiator panel to the AMS, the y angle at which the ISS starboard radiator panel can reflect radiant heat to the AMS with the highest efficiency at specific β can be obtained, marked as yeff. The closer to yeff, the warmer that the WAKE radiator is. The temperature fields on the WAKE radiator of the AMS at the same β but different y presents the confirmation of the calculation. The peculiar manoeuvres of the ISS essentially adjust the thermal environment of the AMS temporarily; the investigation in this part provides alternative methods of adjusting the thermal environment of the AMS for the thermal control of the AMS. The influence of the peculiar manoeuvres of the ISS essentially changed the thermal environment temporarily, which is the reason why the local temperature of the AMS changed. The analysis of the influence provides references for the thermal control of the AMS in operations, and in addition provides references for the thermal design of scientific instruments working on space platforms.In the on-orbit operation, temperature warnings occurred for the environmental factors. The components with temperature warnings can work normally, but actions shall be taken to avoid the temperature going worse. By analysing the orbit-minimum (orbit-maximum) temperature of the components on which low (high) temperature warnings occurred, the specific β intervals at which temperature warnings easily occurred were obtained. In addition, the influence of the peculiar manoeuvres of the ISS on 3 components i.e. the canister in the circulation box (Box-C canister) of the transition radiation detector, the central area of the tracker plane 1 and some photomultiplier tubes in the lower time of flight counter was analysed. Based on this analysis of adjusting thermal environment of the AMS, possible solutions were proposed for the on-orbit thermal control to the unusual temperature phenomena.The investigation and analysis in this dissertation provide new thoughts for the thermal control design of scientific instruments working in space, provide reference for the thermal control design when accounting the influence of the space platform to the potential instrument, and provide an alternative approach for the thermal control of the AMS in long-time orbit operation. |
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