1. Solar Orbiter EUI Extreme UV Imager
SO Cleanliness Working Group #24
Stevenage 10 – 12 October 2017
Jean-Philippe Halain
Udo Schühle (MPS)

2. Outline
Summary of individual instrument status (including final bake-outs overview);
open issues affecting cleanliness and contamination, including evaluation of the impacts of the current Airbus contamination predictions;
status of action items (including evidence of closure, where applicable).

3. a) Summary of EUI project status
EUI flight model
Three units delivered
+ harness

4. a) Summary of EUI project status
S/C activities
CEB
FM unit installed on S/C panel
PRT installed
S/C harness modified
Electrical tests to be performed
Harness
To be installed

5. a) Summary of EUI project status
S/C activities
OBS
Delivered to ADS in May 2017
Pre-handover functional check OK, using FS CEB
Panel flatness checked (< 0.05 mm)
Handling jig fixation to OBS unit improved
Kapton collar installed on entrance baffles
Helicoils replaced by self-locking helicoils
Thermal straps installed on OBS interfaces
OBS mounted on platform
Harness fixation on OBS back panel to be performed
Alignment to be performed
Electrical tests to be performed

6. Cleanliness status OBS cleanliness status (summary)
Cleanliness and Contamination Report
RP-CSL-SOEUI-17053, Iss. 1, Rev. 2 ( )
MOC measured
After assembly: < 0,2 g/cm²
After TVAC / Bake-out: < 0,2 g/cm²
At delivery: < 0,2 g/cm²
PFO measured
At delivery 149 ppm (over 101 days)
Intermediate cleaning of internal cavity during assembly
External surfaces cleaned before delivery
Bake-out
70°C for 72 hours
TQCM deviation of linearity (f”/f’) ~ 0,37% after 40 hours
RGA major peak (water) at 8x10-7 mbar partial pressure

7. Cleanliness status OBS Assembly Airborne counter log: ISO 5 conditions
During the overall assembly time period an airborne counter was located next to the OBS unit.

8. Cleanliness status OBS assembly
MOC witness sample monitoring: < 0, g/cm²
10/01/2017
06/02/2017
06/03/2017
Witness samples located in the CSL cleanroom are monitored monthly, showing cumulative molecular
levels.

9. Cleanliness status OBS TVAC
MOC witness sample monitoring: < 0, g/cm²
17/04/2017

10. Cleanliness status OBS bake-out
all sub-systems baked out before assembly
TQCM
Deviation of linearity (f”/f’) ~ 0,37% after 72 hours
RGA monitoring
all sub-systems have been baked out before assembly

11. Cleanliness status OBS at delivery PFO MOC 149 ppm over 101 days
Cleaned before delivery
MOC
<< 40 ng/cm²
The PFO witness sample that is following the OBS FM unit since its AIT start in January has been
analysed. A total of 149 ppm over 101 days was collected, i.e ppm/day (much better than required
in a ISO5 cleanroom). The OBS unit has however been cleaned many times along that period and the
effective particulate cleanliness level is thus below the required 100 ppm on external hardware surface as
specified in [RD 4] and in EID-A.
The measured MOC level is much below the limit of [RD 4] and in EID-A, of 370 ng/cm².

12. Cleanliness status CEB cleanliness status PFO Bake-out
Build & test:10 ppm
Vacuum bake-out: 6 ppm
Packaging: 3 ppm
EMC test: 200 ppm (before cleaning outgoing inspection)
TVAC: 3 ppm
Total: 220 ppm
Bake-out
80°C for 90 hours,
TQCM ≤1% outgassing deviation from linearity after 20 hours
RGA major peaks above 40AMU < 8.0x10-10 mbar partial pressure

13. Project status
CEB bake-out
TQCM
RGA

14. b) open issues affecting cleanliness
Contamination analysis SOL.S.ASTR.RP.00037:
Table 5.4: molecular contamination during ground tests: The EUI EXT HW sensitive surfaces are inside the S/C cavity which should accumulate MOC at a predicted rate of 0.2 ng/day, while the table shows 1 ng/day.

15. c) status of action items
AI#22: Airbus-DS, ESA and instruments teams to review which materials may need to be tested. The solar array CDR is scheduled for June 2017.
EUI exposed to UV are the Entrance Baffle and the Internal Doors surfaces. They are all made of aluminium. No test required.
AI#24: Airbus DS plans to remove instruments covers during TV activities. Instruments teams to check compatibility of covers’ materials with thermal vacuum conditions if covers need to be maintained.
EUI covers need to be removed before TV test.
AI#26: Instruments teams to provide relevant information on frequency of measurements and handling of contamination witnesses at Airbus DS.
EUI contamination witnesses have been removed and analysed. Further monitoring to be made by Airbus DS.
Δ-CDR AI#1: ESA to ensure that each instrument PI will need to study the updated
SOL.S.ASTR.RP and the impact of the spikes on their instruments and
implement operational constraints in their instrument user manual.
open