Cryomodule Shipping at JLab: SNS and LCLS-II Naeem Huque On behalf of the transportation teams of LCLS-II and SNS TTC2019, Vancouver

Introduction Cryomodules have been fabricated and shipped from JLab for SNS and LCLS-II Twenty four SNS cryomodules were shipped from JLab to ORNL (~500 miles) So far, two tunnel-ready LCLS-II cryomodules have been delivered to SLAC (~3000 miles) from JLab

LCLS-II Shipping System Shipping System Features: Shipping Frame with an inner bed attached via springs Trailer fitted with Air-ride suspension Shipping caps restraining the movement of the cold mass during shipment The system was designed to limit shocks on the CM to +/- 1.5g in all directions

LCLS-II Prototype Testing Road testing of the JLab Prototype (pCM) was intended to commission the shipping system The pCM traveled: JLab to Bristol, VA (750 miles) JLab to FNAL (900 miles) FNAL to JLab (900 miles) The pCM was tested at 2K before and after the trips Fiducial points on the cavities, gate valves, support posts, and vacuum vessel were measured to check for deformation Cavity passbands were compared before and after each trip Beamline and Insulating Vacuum was monitored After reported failures, J07 also taken on Road Test to Bristol, VA

Road Test Highlights Shocks higher than 1.5g spec A number of nuts and bolts found loose Some fiducial points found to be out beyond the +/- 0.2mm spec No loss in beamline vacuum Cavity performance unchanged No additional field emission Tests considered successful on pCM and J07 For J07, beamline vacuum intact, alignment within spec High shocks on first test run alleviated by changing strapping system Gate Valve Fiducials   dX (mm) dY (mm) dZ (mm) Specification ± 0.20 Upstream -0.02 -0.38 -0.19 Downstream -0.05 0.04 -0.44 Error ± 0.10

Road Test Issues Clamps securing the pCM to the frame came loose during the JLab – FNAL trip The pCM’s movement caused unusually large shocks on pCM Cavity performance still unchanged No extra field emission Beamline vacuum intact Fiducial positions mostly within spec Gate Valve Fiducials   dX (mm) dY (mm) dZ (mm) Specification ± 0.20 Upstream 0.433 -0.010 -0.134 Downstream 0.178 0.251 Error ± 0.10

Production CM Shipping Failures Shipping caps on F06 were installed incorrectly, and pushed against the cavity string The FPC bellows in F06 failed on its trip to SLAC The bellows failed due to excessive motion in the beamline direction The assembly had a resonant frequency of 15 Hz, which was excited during transport Fasteners in the BPM assembly also became loose, breaking the vacuum seal The fasteners were found to be Grade-2 Titanium instead of the specified Grade-5 The SHCS were installed without washers Photos courtesy FNAL

Production CM Shipping Failures Why were the JLab pCM and J07 trips successful? BPM on JLab pCM used SS studs and bronze nuts, as Gr-2 Ti SHCS used on production CMs were not available The bellows spool may have been in contact with G10 Shipping Support on J07, restricting movement, and raising the resonant frequency above the excited 15 Hz A bellows convolution protector present on pCM and not production CMs. The protector reduced bellows motion.

Shipping Remedies: Softer Springs The shock spec was changed to from +/-1.5g to: +/- 0.3g Beamline +/- 1.0g Vertical +/- 0.3g Lateral A parameter study with different spring configurations found a reduction from 32 to 8 springs met the new spec Road tests with a concrete CM were used to prove the results

Shipping Remedies: Bellows Restraints Bellows failed due to excessive motion in the beamline direction A neoprene restraint, the M-Mount developed to reduce the motion M-Mount could be installed on completed CMs through the tuner access port Restraint was tested on a shaker table and F05 (after failure)

Shipping Remedies: Bellows Restraints On shaker table, M-Mount reduced bellows displacement from +/-1.2mm to +/- 0.4mm On F05 road test, the displacement on Cavity 4/5 was reduced from +/- 2.6mm to +/- 0.85mm Resonant frequency in the beamline axis was increased from 15Hz to 30Hz The restraint was considered successful To date, five CMs have been delivered to SLAC using the M-Mount Analysis courtesy of Jeremiah Holzbauer and Chris Adolphsen

SNS Shipping System Shipping Fixture consisted of two frames, separated by 12 helical isolator springs (Aeroflex CB1500-15-C2) 1 inch thick rubber between CM and cradles on the inner frame Fixture is designed to reduce shocks by a factor of 6 Cryomodules held on to the frame by ratchetting straps Shipping assembly was fitted on a drop-trailer with air-ride suspension SNS CMs were designed to withstand: Vertical: +/- 4.0g Beam-Axis: +/- 5.0g Transverse +/- 1.5g

SNS Shipping Tests A preliminary test was carried out at JLab using a Quarter-Cryomodule (2000) The QCM was fixed to a rigid frame, with 1 inch of rubber padding on the cradles Sensors to measure vibration and shocks QCM was cold tested after the road test After the test, vacuums and cavity passbands were unchanged One beamline flange moved 0.3mm (vs. +/- 0.5mm spec) All shocks were below the SNS design loads Maximum Shocks (g) Vacuum Vessel Beamline Vertical 2.8 0.9 Beam-Axis 1.9 1.3 Transverse 1.6 1.4

SNS Shipping Tests The test was repeated with the prototype High-Beta cryomodule (2002) The CM was loaded on to the shipping fixture, and the assembly installed on a trailer fitted with Air-Ride suspension The load was driven 400 miles around Virginia The inner conductor of the FPC was restrained Maximum shocks all within design limits Shipping Fixture deemed successful

SNS Production Shipping After successful road tests, SNS cryomodules shipped to ORNL at a rate of one per month Shocks and vibration data were recorded for all shipments High shock was recorded while loading the CM into the fixture; procedure was modified to be ‘softer’ Highest shocks were found to be at the ORNL gate! One cryomodule, HB01 suffered a beamline vacuum leak during shipment Not initially reported, and CM functioned with field emission and lower energy The Shipping Fixture is to be modified (due to changes in End Can design) to transport 7 SNS-PPU cryomodules to ORNL from JLab in 2021

Cryomodule Shipping Lessons Install maintenance ports on vacuum vessels Tuner access ports on LCLS-II CMs have been used for nearly everything but repairing tuners Conduct shipping road tests prior to starting production shipments Include shock and vibration spectra separately when creating a shipping specification Consider sub-component testing of sensitive items (e.g. couplers, tuners, bellows) Ensure assembly used as testing bed is identical (in sensitive regions at least) to production units Involve industry at an early stage of shipping scheme development In addition to paid consultants, some specialized transportation companies may provide advice as part of bidding process Only employ companies that work with special loads Variables such as route, speed, road conditions and weather cannot be controlled; a shipping system should be able to handle deviations

Acknowledgements LCLS-II Transport Team: SNS Team: Brian Hartsell, Jeremiah Holzbauer, Josh Kaluzny, Chris Adolphsen, Rob Coy, Ed Daly, John Fischer, Jared Martin, Peter Owen, and Larry King SNS Team: Tim Whitlach, Katherine Wilson, Mark Wiseman, and Ed Daly