Solar Probe Plus FIELDS SCM FM2 Sensor iPSR SCM thermal vacuum test April 17th to May 3rd 2017

General overview Place : Institue of Space Astrophysic (IAS, Orsay) URANUS chamber Agenda : Test setup April 18th Pumping for vacuum : April 18th to 20th Cycling : April 20th to May 2nd Back to ambient : May 2nd to May 3rd Dismounting : May 3rd URANUS chamber

Test configuration Thermocouples will be mounted along the flight unit, harness and environment to verify temperature during thermal cycling Name Place TC_ANT_EXT3 On the bottom of the double band antenna N°3 TC_ANT_EXT2 At the bottom of the mono band antenna N°2 TC_ANT_EXT1 At the bottom of the mono band antenna N°1 TC_PEEK_FLAT On a flat area towards +Yurf (above the bedplate titanium pin) TC_URP At SCM URP as defined in MICD TC_IFsensor At the bottom of the foot facing TC_SRPsensor located on the support TC_BEDPLATE_TOP On the top of the bedplate TC_HARN_OUT On the harness just at the output of the foot TC_CONN On SCM harness connector Name Place TC_SRPsensor On the mechanical support very close form TC_IFsensor TC_SRPsensor_red Redundancy of TC_SRPsensor at 180° TC_SRPbedplate On the mechanical support very close form the bedplate TC_PLATE On the regulated plate of the vacuum chamber TC_MUext_TOP On the top, outside the external mumetal can outside TC_MUext_BOT At the bottom, outside the external mumetal can TC_MUint_TOP On the top, inside the internal mumetal can outside TC_MUint_BOT At the bottom, inside the internal mumetal can

Test configuration SCM on support with TC SCM inside the chamber

Test configuration Radiative hood implemented Contamination witness below Final configuration with mumetal cans Cans covered with kapton Harness taped on the plate to avoid leaks

Temperature profile Hot op 1 to 6 Hot non-op WC TC : 82.21°C Recorded temperatures (thermocouples) Cold non-op WC TC : -60.42°C Cold op 1 to 6 WC TC : -56.2°C

Temperature profile Secure configuration for Saturdays and Sundays : SCM OFF, ambient T° Configuration used to faster the transitions : Transition from cold to hot dwells : use of SCM heater 1W during 3 hours 0.5W up to 80°C for the preamplifier HK probe (~45min) Temperature monitored to keep the slope below 1°C/min Transition from hot to cold dwells Target temperature -75°C on the regulated plate and screen 5h dwell Target temperature -65°C (necessary to have preamp belo -55°C specified for test) on the regulated plate and screen

SRP target T° (facility) Temperature profile Stability and temperatures reached Soak date Specified T° SRP target T° (facility) end of soak T° soak duration rate of change Comments WC (1) 1°C/h and temp. reached WC (2) on 1h Non operational hot 20/04/2017 85 86 85.39°C 2h 0.12°C/h at t-3h stable but +84.82°C on antennas cold 21/04/2017 -60 -63 -60.42°C 0.3°C/h at t-3h stable but -59.51°C on antennas Operational 1 24/04/2017 80 82 81.33°C 4h 0.98°C/h   -55 -54.44°C 0.79°C/h only TC_PEEK_TOP above -55°C Operational 2 25/04/2017 82.64°C 0.62°C/h at t-3h 1.68°C/h -65 -56.20°C 0.03°C/h Operational 3 26/04/2017 82.58°C 0.9°C/h at t-3h 2.5°C/h on antennas -58.62°C 3h 0.76°C/h at t-1h 1.1°C/h on antennas Operational 4 27/04/2017 82.61°C 0.74°C/h at t-3h 2.1°C/h on antennas -58.13°C 0.05°C/h Operational 5 28/04/2017 82.56°C 0.95°C/h at t-3h 2.71°C/h on antennas -58.14°C Operational 6 02/05/2017 82.21°C 0.92°C/h at t-3h 2.59°C/h on antennas -62.31°C 0.86°C/h Target temperature for cold dwells changed from -63°C to -65°C after cold dwell 1

SCM verification tests Good health test performed at each dwell Frequency sweep on 4 channels using the onboard calibration Power consumption Thermal devices resistance measurement → consistent values for thermistors, 4 delta (depending on T°) for heater Ambient Cold hot +12V 13.3mA 12.6mA 13.4mA -12V 13.5mA 12.9mA 13.6mA

SCM verification tests Measurements more or less noisy because of 50Hz and harmonics (despite the 2 mumetal cans) Influence of the temperature on performances Same levels at hot temperature Lower gain at cold temperature outside the band [40Hz; 10kHz] Cycle 6 LF1y : delta gain (dBV/nT) with ambient Freq. cold hot 20Hz -0.50dB 0.07dB 100Hz Not visible 50Hz 1kHz -0.32dB 0.10dB 10kHz -0.30dB

SCM verification at LPC2E Frequency response curves are superimposed LF1y before and after thermal vacuum

SCM verification at LPC2E No variation of the noise level LF1y before and after thermal vacuum

Visual inspection Connector and harnesses : ok EC2216 glue joints : ok Bolted interfaces : fastening torques verification Bedplate/SCM interface 2.6N.m → no additional rotation Support/bedplate interface 3.5N.m → rotation 10° for all screws (torque defined for titanium whereas the support is in aluminum) Screws and inserts : threads and surface treatment ok Bedplate and foot inspection : ok Traces of glue (tape used for TC) on PEEK  cleaning with IPA

Conclusion Specified temperatures reached except 1 time for 1 TC -54.4°C instead of -55°C considered acceptable Stability criterion reached at least on 2 hours (RFD issued) No significant degradation of the mechanical hardware No impact on SCM performances (frequency response and noise level curves are superimposed) and behavior (power consumption, thermal elements) The failure occurred on FM1 was not observed  Thermal vacuum qualification test is considered successful Ongoing tasks: test report, data provided by the test facility are expected Analysis of the contamination witness

Back up

SCM verification tests Cycle 6 MF4x : delta gain (dBV/nT) with ambient Freq. cold hot 10kHz 1.2dB 0.05dB 100kHz 0.03dB Note : onboard calibration defined for LF channel, not well adapted for MF