LCLS-II-HE Activities at Fermilab

LCLS-II “High Energy” (LCLS-II-HE) is a planned upgrade project to the LCLS-II. Twenty-three 1.3 GHz cryomodules will be built by Fermilab and Jefferson Lab, each containing eight 1.3 GHz 9-cell superconducting radiofrequency (SRF) cavities. The cryomodule design remains nearly unchanged relative to the original LCLS-II superconducting linac. However, there is a significant change in cavity performance specifications. Motivated by limitations in available tunnel length, the average accelerating gradient is increased from 16 MV/m in LCLS-II to 20.8 MV/m in LCLS-II-HE, corresponding to a total module voltage of 173 MV. Like the original LCLS-II cryomodules, the LCLS-II-HE cryomodules will operate in continuous wave (CW) mode, meaning that achievement of high Q0 in the cavities is crucial to keep the cryogenic heat load manageable.

Fermilab’s scope of work for LCLS-II-HE includes:

  • High Gradient – High Q0 R&D program: LCLS-II uses the breakthrough nitrogen-doping technology invented at Fermilab to improve the quality factor (Q0), lowering the both cost of the cryogenic plant infrastructure and the operating costs. With the contributions from Fermilab, Jefferson Lab and SLAC, for LCLS-II-HE, an R&D effort has been successfully completed to develop a new cavity processing protocol and transfer the technology to industry.
  • Design, fabricate, test & delivery thirteen 1.3 GHz cryomodules
    • Fermilab is responsible for the design
    • Fermilab and JLab share production of 1.3 GHz cryomodules
    • Fermilab is responsible for the 1.3 GHz Buncher Capture Cavity cryomodule (for SRF injector) mechanical-cryogenic design, procurement, assembly, test & deliver
  • Assistance to SLAC with design & procurement of cryogenic distribution system
  • Assistance to SLAC with the procurement of cryomodule interconnect components
  • For above deliverables provide installation and commissioning support at SLAC

Fermilab has successfully completed LCLS-II scope and has delivered the last LCLS-II cryomodule (CM) to SLAC in March 2021. LCLS-II CM production at Fermilab has brought technical readiness and important lessons learned for LCLS-II-HE. We have developed a strong team. We have proven that our team of people worked well together internally and externally and produced excellent results. The Fermilab team has demonstrated the capability of producing world record performance cryomodules on schedule and on budget. The push for even higher performance for LCLS-II-HE is progressing well with the vCM successful assembly and excellent test results. At Fermilab, production of series cryomodules will start in the Fall of 2021.

Fermilab infrastructure and team are ready and fully committed to deliver its scope for the LCLS-II-HE!