SNS PPU CRYOMODULE PRR Cavity Preparation Testing and

SNS PPU CRYOMODULE PRR Cavity Preparation, Testing and Acceptance Kirk Davis, Danny Forehand February 19 -20, 2020

Outline • Cavity Receipt Inspection • Cavity Incoming Visual & Dimensional Inspection • Cavity Incoming RF Inspection • Cavity Preparation for qualification test • Cavity Vertical Test • Cavity rework • Lessons learned • Challenges 2

Cavity Qualification: Overall Schedule 3

Cavity Processing and Qualification • Process Flow 4

Cavity Inventory Traveler (SNSPPU-INV-CAV) performed by SRFOPS Inventory technicians. Cavities are received under vacuum and ready to test. 1. Records cavity serial number 2. Visually inspects packaging as received 3. Visually inspects cavity as received 4. Records concerns for closer inspection during subsequent CMM and RF inspections. This may include NCR or D 3. 5

Cavity Incoming Visual & Dimensional Inspection • Cavity Incoming Visual & Dimensional Inspection Traveler performed by SRFOPS metrology technicians (SNSPPU-CAVINSP-CAV). 1. Detailed visual inspection of cavity. 2. CMM measurement of critical dimensions vs acceptance criteria. 3. Record results for cognizant engineers. This may include NCR or D 3. 6

Cavity Incoming RF Inspection • Cavity Incoming RF Inspection performed by SRFOPS RF technicians (SNSPPU-CAV-RFIN). 1. Insures that cavity is tuned and probes are set for vertical testing. 2. RF measurement of critical parameters vs acceptance criteria. 3. Record results for cognizant engineers. This may include NCR or D 3. 7

Cavity Preparation for qualification test • Cavity Assembly to Test Stand performed by SRFOPS chemistry and cleanroom technicians (SNSPPU-CAVASSY-TSTD). 1. Cavity is cleaned for entry to cleanroom. 2. Cavity is mounted to a vertical test stand. 3. Leak check test stand. 4. Pump cavity to re-establish vacuum and leak check. 5. Record results for cognizant engineers. This may include NCR or D 3. 8

Jefferson Lab Vertical Test Area • Eight Vertical Dewars －Radiation Shielding (6/8) －Magnetic shielding and compensation coils (7/8) －Over 5000 vertical cavity tests since 1995 －LHe supply 150 L/hr steady state (450 L/Hr short-term) －Recent upgrade projects: • PLC-based cryo controls • Digital LLRF systems • 805 MHz RF Power Amps 9

Production Cavity Vertical Acceptance Testing - Work flow & throughput - Goal: qualify one cavity every two weeks on average - “Busy week” test one cavity per week, 30% fail/rework - Schedule risk mitigation – - Three dewars are appropriate for PPU cavity testing (D 5, D 7, D 8) The baseline rate of one vertical test per week can be achieved using one dewar, - - D 7 and D 8 are faster turnaround because of smaller size D 7 and D 8 are in higher demand by other projects Cryo plant is shared between cryomodule test and vertical test - Cryomodule cooldowns are scheduled for weekends Careful cryo coordination between CMTF and VTA is required 10

Production Cavity Rework - Failed Vertical Test (commonly Field Emission) - Return cavity to cleanroom Remove from test stand External cavity cleaning Vent cavity Complete disassembly Clean parts 1 st high pressure rinse cavity, dry pre-assembly (partial) 2 nd high pressure rinse cavity, dry Final assembly Evacuation Leak test Mount to test stand repeat vertical test 11

Lessons Learned - Dedicated vertical test stands save time and money - Close coordination between VTA and CMTF is needed - Parts in circulations don’t always circulate 12

Challenges - Slow pumping systems are in high demand, short supply Dewars 7 and 8 are in high demand, D 5 is logistically painful to fill Cleanroom real estate is shared with multiple projects Hiring and training for cleanroom and chemistry techs 13

Alternate paths • Active pumping during vertical RF test or isolated cavity • Vendor relocate burst disc to the bottom of the cavity assembly 14

• Cavity receipt and inspection • Cavity prep for vertical test • Vertical RF test • Cavity rework • Lessons Learned • Challenges • Alternate paths 15