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X-Ray Calorimeter Mission

X-Ray Calorimeter Mission. Flight Mirror Assembly Thermal Analysis Mike Choi 2-6 April, 2012. Flight Mirror Assembly (FMA) Thermal Requirement. Mirror temperature requirement: 20˚C±0.5˚C. Flight Mirror Assembly (FMA) Thermal Requirement.

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X-Ray Calorimeter Mission

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  1. X-Ray Calorimeter Mission Flight Mirror Assembly Thermal Analysis Mike Choi 2-6 April, 2012

  2. Flight Mirror Assembly (FMA) Thermal Requirement • Mirror temperature requirement: 20˚C±0.5˚C

  3. Flight Mirror Assembly (FMA) Thermal Requirement • Mirror segments view space at one end and metering structure at other end

  4. Thermal Model Parts Identification Mirror Module Non-Conductive Pre-Collimator: 13.6 cm Tall Mirrors

  5. Worst Cold Case Temperature Predictions without Heaters on Metering Structure: BOL and -45˚ Pitch ˚C S/C Exterior (Sunside) ˚C Mirror Segments Sunside Anti-sunside ˚C No Heaters On Metering Structure. Heaters On Conductive Portion of Pre-Collimator and Module Walls. Poor Temperature Gradient. NOTE: Baseline pitch is ± 25 ºC Metering Structure

  6. Worst Cold Case Temperature Predictions without Heaters on Metering Structure: BOL and -25˚ Pitch S/C Exterior (Sunside) ˚C Mirror Segments ˚C Sunside Anti-sunside ˚C No Heaters On Metering Structure. Heaters On Conductive Portion of Pre-Collimator and Module Walls. Poor Temperature Gradient. NOTE: Baseline pitch is ± 25 ºC Metering Structure

  7. Metering Structure Temperature Control • Without active heater control on metering structure, mirror temperature gradient exceeds thermal requirement significantly • Active heater control on metering structure is required • First 1.5 m of metering structure is actively controlled to 22.8˚C ±0.25˚C • Heaters and thermistors are attached to exterior of metering structure

  8. Worst Cold Case Temperature Predictions with Heaters on Metering Structure: BOL and -45˚ Pitch ˚C S/C Exterior (Sunside) Mirror Segments ˚C Sunside Anti-sunside ˚C Heaters On Metering Structure. Heaters On Conductive Portion of Pre-Collimator and Module Walls. Heater Power : 647 W peak (453 W average) for 24 Mirror Modules. Metering Structure

  9. Worst Cold Case Temperature Predictions with Heaters on Metering Structure: BOL and -25˚ Pitch ˚C Mirror Segments ˚C S/C Exterior (Sunside) Sunside ˚C Anti-sunside Heaters On Metering Structure. Heaters On Conductive Portion of Pre-Collimator and Module Walls. Heater Power : 637 W peak (446 W average) for 24 Mirror Modules. Metering Structure

  10. Heater Power Summary *Average is peak multiplied by 70% duty cycle per GOLD Rules. **Heater resistance is sized based on Vmin2/R=647. ***319 W at -25˚ pitch or 326 W at -45˚ pitch for metering structure (~70% of total FMA heater power).

  11. Conclusions and Recommendations • Active heater control for first 1.5 m of metering structure is required • FMA heater power requirement in worst cold case for -25˚ pitch is 446 W average (i.e., 637 W at 70% duty cycle) • Changing pitch angle from -45˚ to -25˚ reduces average heater power by only 7 W • Approximately 70% of FMA heater power is for metering structure • More iterations on heater controller set points will be required to achieve close to optimum mirror temperature gradient

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