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

2. 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

3. 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

4. Test configuration
SCM on support with TC
SCM inside the chamber

5. 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

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

7. 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

8. 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 °C on antennas
cold
21/04/2017
-60
-63
-60.42°C
0.3°C/h
at t-3h stable but °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

9. 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

10. 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

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

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

13. 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

14. 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

15. Back up

16. 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