Mar 17, 2022 - Update Meeting

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  • NEG screens - Marcy
    • Screen still on design
    • Still need from ME: Define extact dimensions to make it symetric
    • Marcy to meet with Shaun
  • Vacuum chamber
    • Phil - Anything else to be done to the chamber (fiducial fixtures? support base? etc.)
    • Chamber baked after swaping leaky extractor gauge
    • Baseline presure measurements in progress, no NEG activation with current. RGA valved out
    • Forecast end of vacuum measurements TBD: Pressure is higher than expected.
    • CEBAF gun chamber are 316L
    • 18" GTS and second chamber they are 304 SS ~ good outgassing, but has magnetic permeability
    • How is the vacuum bake going? Marcy / Phil
  • Gun table layouts (UITF, CEBAF) - Shaun
  • Anode tube versions
    • Shaun sent Gabriel models for the 12 narrow and for the 6 wide slot tubes
    • Gabriel has done simulation of the beam deflection with these 2 models. Slides can be found here
    • The 12 slot tube seems to have a lesser effect on beam kick compared to the 6 slot tube
    • Gabriel and Carlos will discuss next week with Joe results from electrostatic models with various biasing options. This is to pick the best tube version (12 narrow slots, or 6 wide slots)
  • These are the models for the anode drift tube with 12, 0.5 inch wide slots (blue) and another tube with 6, 1.0 inch wide slots.
  • Tilted anode and tube with 12 and with 6 slots.png
  • The electrodes and anode have been vacuum degassed to 950 C for 6 hours by S. Williams with the resulting sun profile shown below.
    • InjElectDeg950 6hrs 031522 1040 data plot.jpg
  • The electrode have been store din containers ready for UHV cleaning in the production chem room just prior to assembly.
  • Electrodes in containers after 950 C vacuum degassing.jpg
  • The ball electrode after the vacuum degassing run profile shown above (950 C for h)
  • Electrode ball after 950 C for 6 hours vacuum degassing.jpg
  • Comments form Scott Williams:
    • Wwe still experienced some cloudiness on these parts even though they were shielded in SS huts. I'm starting to suspect that we may be venting the furnace too early even though thermocouples were reading 40C (actual parts much hotter). This cloudiness/oxide may be forming once we open the furnace door to air. I suggest that the next time we do this process that we do it at the end of the week and let cool over the weekend to see if this makes a difference

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