May 1 2024

Updates

• Electrode assembled with 16/30 front end, surveyed and installed to 18" gun high voltage vacuum chamber on April 25 2024. This assembly is now R30-4.
  • https://logbooks.jlab.org/entry/4288727
• Laser retro-reflection evaluation
  • File:R30-4 gun electrode assembly + laser retroflection evaluation April 2024.pptx
• R30 gun high voltage chamber supporting fixture
  • The first version of the R30-type gun (18" chamber) supporting fixture was intended to aid in aligning the gun high voltage chamber to the photocathode preparation chamber VAT valve flange. Although the fixture provided desired alignment, it did not provide means for smooth z-displacement needed for clearing the 4-1/2" VAT valve flange studs on the photocathode preparation chamber.
  • A revised version was designed with rails and a crank handle for smooth z-displacement. Two fixtures were made for the R28 style gun (14") gun chambers. One was installed and proven very effective in the UITF. The high temperature resistant teflon pads riding on the rails survived the 250C gun bake w/o issues.
  • The second fixture was stored in TL1137, but because the R30 gun chamber is 2" in radius larger than the R28, the fixture height was revised.
  • A new set of shorter V-blocks and shorter threaded rods will be fabricated. The fixture will have to be installed without the 0.5" tall spacers used in the UITF for the R28 gun.
  • File:R30-4 gun supporting fixture by Gary HAyes April 2024.pptx
    

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