This afternoon, Travis and I pulled the First Contact on the ETMY HR surface. WE measured charge via the standard procedure at the back of the AERM before and after. We had a hard time blowing with 10-20psi DI N2 to reduce the charge originally at ~12V to under 3V. More detail on this in attached alog shortly.
AFter we were satisfied with the final "dis"charged state, we then set the lower earthquake stops/lock nuts on the ETMY, and pulled the ACB (arm cavity baffle) back down into it's nominal position. I noticed however that the ACB felt like it was rubbing on something when I bounced it vertically. Inspection revealed that one of the earthquake (EQ) stop bars D1201235 was rubbing the down tube in the roll direction. I moved weights around on the top of the box in an attempt to free it, however I ran out of range. Either this unit has been rubbing for a while, unnoticed, or sometime during this last few months of vent work we jostled it enough to twist something like the flexture, blade, down tube shaft, or box. In consult with Calum and Jeff K, the consensus was to just remove this EQ stop bar since it only constrains the ACB in the less critical roll and yaw motion which have other mechanical backup restraints. Of course removing the long bar proved difficult because it was trapped between the unit and the chamber wall. Travis was able to convince it to come out via bending it's tip.
Will file an FRS for this to be investigated further when we have more time/people power than today's closeout mustered up.
After Jim unlocked the ISI, Travis cleared the chamber of tools/stools/CC supplies. Note, we did not pull any of the freshly placed 3" or 1" samples in this chamber left during closeout just a few weeks ago - all CC kits had already been pulled and I could not organize to get help with this.
Travis and I have been running TFs on the main and reaction chains of ETMY and things look good. We are good to put the door on tomorrow morning asap. (Note, Mark D and Tyler have it hanging on the engine hosit ready to go.)
Picture of EQ bar that was rubbing before removal, and picture of ACB from beam view down tube for overview.
Hand-held electrometer readings at back of ETMY QUAD (AERM back surface), mounted in the center, UL and LR locations:
Picture of ETMY unused, broken Ring Heater temp probe, stowed under optic on structure.
A few more pics of the lifted ESD strain relief on the top of the ETMY AERM mass, FRS 10181.
Particle counts, measured with hand held unit just inside the chamber, a few times throughout these 2 closeout days were 0-30 for all sizes measured between 0.3-1.0microns.