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| − | Participants: Tim, Dave, Simon, Beni, Chris, John, Casey, and Lubomir. | + | Participants: Bill, Dave, Chris, Nick, Mark, Simon, Beni, Eugene, and Lubomir. |
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| | == Production == | | == Production == |
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| − | - Dave: Remaining to be done on package #3: last two wire frames to be electroplated and Chris has to put the elements on one of them; daughter cards on one type-2 cathode to be installed. Package #4: all wire frames were laminated, on three the caps were already replaced and tested and Anatoly is working on the fourth one; one wire frame strung. The plan is to stop the installation of the third package, stop the wire frame production after finishing the last one and stop at least by Monday the cathode production. The hope is by that time we will have an idea how to fix the oxygen leakage into the chambers. | + | - Dave: Chris put components on two wire planes for package #3, they remain to be deadened. Anatoly is gluing dauther cards on cathodes for package #4. One end window for package #4 that was recently made has a wavy mylar surface. We suspect the surface of the transfer ring was slippery, since before it was used to tension clear mylar for the gusset ring. The rule will be always to sand the transfer ring before using for the end windows. We will have to redo the end window: first sand the old mylar and tension it again. |
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| − | - Lubomir: fourth cell of the third package was tested with a source and a scope. All channels are OK, but a leakage was found at the top end window. | + | - On Monday we disassembled the third package. The old O-rings of the two end windows and the wire frame for the first cell were removed using aceton to clean the super glue. Casey inveted a cover for the wires to prevent aceton spills. Then the grooves were double coated with Hysol, Viton O-rings were installed today and we assembled the first cell right after the meeting. Dave wrote the procedures for the replacement of the O-rings waiting now for signatures. |
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| | == Oxygen contamination in the first package == | | == Oxygen contamination in the first package == |
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| − | - Beni: after replacing the plastic rods on the first package with aluminum ones the pressure inside the chamber increased from 70 to 110 Pa. To keep the pressure the same we had to decrease the flow from 200 to 300 scc/min. So, the main effect was that we improved the tightness of the chamber significantly but the oxygen percentage improved just a little (~10%). | + | - |
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| − | - Replacing the old O-rings (EPDM) with new (Buna-N, or Nitrile) on the testing chamber resulted in decreasing the oxygen from 1400 vpm to 940 vpm (in three days, last value stable for several hours) which is not enough. The configuration of the testing chamber was from bottom to top: Lexan, spacer ring with two new O-rings, cathode type-2, end-window with new O-ring.
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| − | - This morning we started a new test without the cathode and end-window so that we can get the results faster without the air-pockets in these elements.
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| − | Configuration: Lexan and spacer ring from before (with the two new O-rings), empty type-1 cathode frame with an old type O-ring on the top, another Lexan sheet. The O-ring on the cathode frame was not glued with super glue (except at two points). If the main oxygen leakage is through the G10 groove/old O-ring we had similar O-ring configuration before but with cathode type-3 and end-window, and expect to see oxygen at ~1400vpm.
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| − | - Future plans: The idea is tomorrow to replace the cathode frame with another one on which the groove was coated today with Hysol epoxy. Dave and Casey made different sample coatings, also diluting the Hysol with ethanol, but we decided to use the non-diluted epoxy since it covers better the G10 fibers at the same time increasing the g10 thickness by only ~1mil. If coating the grooves results in significant oxygen reduction we may want to try next week to see also the effect of the coating AND the new type O-ring. Then we will plan the refurbishing procedures, will start with the third package. We will bring the oxygen sensor to Blue Crab and will measure the oxygen cell by cell before and after refurbishment.
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| | == Engineering == | | == Engineering == |
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