KEK, Ibaraki
SLAC, Menlo Park, California
Fermilab, Batavia
INFN/LASA, Segrate (MI)
DESY, Hamburg
In an attempt at demonstrating an average field gradient of 31.5 MV/m as per the design accelerating gradient for ILC, a program called S1-Global is in progress as an international research collaboration among KEK, INFN, FNAL, DESY and SLAC. The design of the S1-G cryomodule began at May 2008 by INFN and KEK. The S1-Global cryomodule was designed to contain eight superconducting cavities from FNAL, DESY and KEK, and to be constructed by joining two half-size cryomodules, each 6 m in length. The module containing four cavities from FNAL and DESY was constructed by INFN. Four KEK cavities have been assembled in the 6 m module which KEK fabricated. All major components were transported to KEK from INFN, FNAL and DESY in December 2009. The assembly of the two 6-m cryomodules started from January 2010 in a collaborative work of FNAL, DESY, INFN and KEK. The construction of the S1-G cryomodule will complete in May, and the cool-down of the S1-G cryomodule is scheduled from June 2010 at the KEK-STF. In this paper, the construction and the cold tests of the S1-Global cryomodule in the worldwide research collaboration will be presented.
Fermilab, Batavia
Fermilab is currently focusing its efforts toward the development of Stainless Steel (SS) helium vessels for its 1.3 GHz SRF cavities. The objective is to transition towards the concept of using SS helium vessels to dress the bare SRF cavities, thereby paving way for significant cost reduction and efficient production techniques for future accelerators. The biggest challenge has been to design a reliable interface between the niobium cavity end group and the stainless steel end flange that encloses the helium vessel. Fermilab has been pursuing a brazed joint design to allow this transition. Additional design challenges associated with this transition are ensuring proper cooling of the cavity, compensating for the difference in thermal contraction between the SS helium vessel and niobium cavities, and also modification of the tuning procedure and ensuring the safety and reliability of the blade and piezo tuners. Current efforts on the qualification of the niobium-SS braze joint, finite element simulations of the thermal design aspects, bench testing of actual cavity displacements, and study of the effects on the tuners will be presented.
Fermilab, Batavia
Fermilab has produced two cryomodules for superconducting RF (SRF) applications to date. The first of these is an ILC prototype containing eight 1.3 GHz Tesla-type cavities and a superconducting quadrupole. This cryomodule is of the 'Type 3+' design developed by the TESLA collaboration. The assembly of this cryomodule was accomplished at Fermilab with much assistance from DESY and INFN-Milano. The cryomodule was tested at Fermilab in the summer of 2010. The second cryomodule produced at Fermilab contains four 3.9 GHz nine-cell cavities. The cavities and cryomodule were designed at Fermilab; the design concepts are quite similar to the 1.3 GHz Type 3+ cryomodule. This cryomodule was shipped to DESY, tested, and is now operating as part of a third-harmonic system in the FLASH facility. Fermilab plans to build five more 1.3 GHz cryomodules over the next several years for a total of six, which will be installed and operated in the New Muon Lab beam test facility at Fermilab.