Difference between revisions of "Minutes-8-9-2012"

From GlueXWiki
Jump to: navigation, search
(→‎Cathode corrosion)
Line 26: Line 26:
  
 
== Production ==
 
== Production ==
−
 
−
<!--
 
  
 
- Dave showed the latest Construction Tracking file (linked): now refurbishing second package. The plan is to use all the spare cathodes there plus three newly build: all of them using new foils and one spare cathode frame (the only we had), and two refurbished (type-1 and type-2). The refurbished frames came from package #1 by successfully removing the foils. For package #1 we may use some of the cathodes from package #2 that didn't have bad channels (indicated with blue color) and all of the spare foils left after building package #2.
 
- Dave showed the latest Construction Tracking file (linked): now refurbishing second package. The plan is to use all the spare cathodes there plus three newly build: all of them using new foils and one spare cathode frame (the only we had), and two refurbished (type-1 and type-2). The refurbished frames came from package #1 by successfully removing the foils. For package #1 we may use some of the cathodes from package #2 that didn't have bad channels (indicated with blue color) and all of the spare foils left after building package #2.
  
−
- Roger is trying to contact Allflex to order new foils, but the guy is in vacation, will be back on Monday. Roger will ask Allflex also for new rigid-flexes, even it turned out we can re-use the old ones; in fact not all of the removed flexes can be re-used but we will improve the removal procedure. 
+
- Roger
−
 
+
<!--
−
- We are trying to repair one of the damaged cathodes from package #1. First, the traces were covered with conductive ink resulting in <10 Ohm resistance. The trick is to shake the pen very well before using it and to apply very thin layer, actually it can be thinned later using ethanol. Next, the trace/O-ring area of one connector was covered with Kapton using Hysol epoxy. We will test it for leakage. The pen we are using, according to TECHSPRAY data sheets has silver, n-Butyl acetate (as solvent), and polymers. Viton O-ring is not compatible with acetate solvents, but first, the solvent evaporates in an hour time frame, second it's covered with Kapton. We discussed using stencils to cover the traces with conductive ink, it will help but we need to make 9, for each connector.
+
−
 
+
−
- The refurbishment of the package #2 is delayed not only because of the corrosion problem, but also there was a delay with the delivery of the conductive (thermally) rubber that we use to re-heat the cathode rigid-flex connections. There were resistance problems (10-100 Ohm on the contacts) with the two spare cathodes type-3, the very first cathodes produced, that we want to put now in the second package.
+
−
 
+
−
- Vlad on the grounding scheme (linked above): the ground positions shown in degrees starting from North counterclockwise when looking from the upstream of the package. Three types of groundings as shown on the pictures. The clips are supposed to come by August 15, ... procurement forgot to inform the company to go with the full production.
+
  
 
== Engineering ==
 
== Engineering ==

Revision as of 17:54, 9 August 2012

August 9, 2012 FDC meeting

Agenda

  1. Cathode corrosion
  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.

Production

- Dave showed the latest Construction Tracking file (linked): now refurbishing second package. The plan is to use all the spare cathodes there plus three newly build: all of them using new foils and one spare cathode frame (the only we had), and two refurbished (type-1 and type-2). The refurbished frames came from package #1 by successfully removing the foils. For package #1 we may use some of the cathodes from package #2 that didn't have bad channels (indicated with blue color) and all of the spare foils left after building package #2.

- Roger

Retrieved from "https://halldweb1.jlab.org/wiki/index.php?title=Minutes-8-9-2012&oldid=39260"