Minutes-8-9-2012

August 9, 2012 FDC meeting

Agenda

1. Cathode corrosion
   • Status tests with water, SEM results
   • Testing chambers vacuum chamber tests
2. Production Construction Tracking (Dave)
   • Cathode production
   • Fixing cathodes
   • Second package refurbishment
3. Engineering (Bill)
4. Electronics (Chris, Nick)
5. TDR, page 132-145 (Lubomir)
6. Other

Minutes

Participants: Bill, Dave, Chris, Nick, Vlad, Eugene, and Lubomir

Cathode corrosion

- Lubomir: a test with cathode foils, Viton/EPDM O-rings and water was done (at Blue Crab dirty area). First, the O-ring samples were pressed against the foils with a lead brick, also using G10 and aluminum plates to equalize the pressure. After a couple of days, water (from the tab) was put on the samples. Corrosion appeared immediately on the next day: very well pronounced on the EPDM sample and resembling the same dark traces that we had on the cathodes of the first and second packages (see first picture above), also some corrosion but with lighter color on the Viton sample. Olga did SEM analyses on the two sample foils at the places of the O-rings: second link above. Generally, the experiment was not done in a clean environment and tab water was used, so you see a lot of dirty stuff like chlorine. At the same time sulfur is visible in almost all the areas of the EPDM sample, while for the Viton sample sulfur is present in much smaller areas visible with high magnification. We started the same experiment inside the clean room using distilled water; expect results next week.

- Three other test experiments are running. One with production cathodes and a wire frame that started more than two weeks ago. Second one with similar samples using the small-scale prototype, running since yesterday when we were able to fix the HV. The third one is the Vlad's experiment using the vacuum chamber (picture linked) with same samples (EPDM, Viton with/without Apiezon) with same gas, but no HV, with some water inside to create moisture, all this heated with a lamp (only during the day) up to 80degC. It started yesterday; we will open the chamber on Monday.