C 100 Refurbishment Brainstorming Arne Freyberger Geoff Krafft

C 100 Refurbishment Brainstorming Arne Freyberger, Geoff Krafft, and Tony Reilly Also Contributing: G. Ciovati, Need More Contributions!

C 100 Refurbishment • C 100 Refurbishment is now part of the CEBAF Performance Plan. Need to start the planning process now. • Start with assembling a wish list. • At this stage any input from any regular PIT attendee is welcome. • Suggested initial organizing categories －Measurements to be performed during disassembly －Cavity (re)processing to be performed during refurbishment －Best practices re-assembly procedures to apply －Problems in current C 100 s "to fix“ －Reliability improvements (methods to reduce trip/quench rates or FE) －Additional important categories? ? ? 2

Measurements to be performed during disassembly • Leak check both the insulating vacuum and the cavity string prior to disassembly to identify and replace faulty components. (Gigi) • Examine internal and external probe cables for radiation damage (Hovater) (Go to Si. O 2? ) 3

Cavity (re)processing to be performed • Make Cavities Stiffer (Hovater, Drury, Powers) (10 and 20 Hz modes higher and lower their Q (Explicit Dampers (Powers)) Reduce Lorentz coefficient and Hz/Torr • Rinsing or other processing to clean up FE (Drury) 4

Best practices re-assembly procedures to apply • Apply LCLS II and recent C 50 methods/processing leading to reduced FE (Drury) 5

Problems in current C 100 s "to fix" • Tuner rework to improve mechanical response and get piezo update that works (Hovater) Cornell “elegant” piezo idea to incorporate (Rimmer) 6

Reliability improvements (methods to reduce trip/quench rates or FE) • Cavity characterization should take into account actual linac conditions -actual operating temps in the linacs, actual cool down rate capabilities (Drury) • Consider adding a foot in the center of the CM in order to suppress the 20 Hz beam mode. (Powers) • Consider adding some damping to the cryo lines where they come into the CM. (Powers) • Add bolt landing spots on the insulating vacuum vessel for the waveguide to insulating vacuum interconnecting struts. (Powers) • Provide more steps per Hz on the tuner motor (gear box? ) right now it is 9 micro steps to go from 5 degrees detuned to on tune. It would be nice if it were at least 100 microsteps. (Powers) • Add locking nuts to the nonsupporting feet. Currently the flange above them moves 4 mils when someone pushes the insulating vessel latterally. (Powers) 7

SUMMARY Eventual goal: prioritized (in importance) list of items to be included in the C 100 refurbishment plan