02/20/2014
SCU Coordination meeting: Yury, Joel, Marion (ANL), Soren, Diego (LBNL) by video
Agenda: Cryostat technical specifications
Yury sent an initial version of the document below to all parties to start discussion. Each item was discussed in detail and there was general agreement on the scope. Specific details of discussions are noted in italics below each subtopic, and action items are bold.
LCLS-II Superconducting Undulator Prototype Cryostat
Technical Specifications
1.General Information
A superconducting undulator (SCU) prototype cryostat will be built as a part of R&D on superconducting undulators for LCLS-II Project. The cryostat will be used for stand-alone cold tests and magnetic measurements of 1.5-m long NbTi /Nb3Sn magnetic structures. It will not be used for testing the magnets with the electron beam. The design of the cryostat will be based on the design of the cryostat for SCU0 undulator at the APS.
Agreed by all.
2.Beam chamber
Beam stay clear aperture: 5.7 mm
Additional requirements: The beam chamber design shall allow magnetic measurements with Hall probe, stretched coils and pulsed wire on magnetic axis only (?).
Need to verify with SLAC whether off-axis measurements are needed in addition to the on-axis measurements.
Action: Soren will follow up and inform the group.
The possibility of each device using a separate vacuum chamber was discussed and seemed like it could be favorable.
Action: Joel and Yury will provide beam chamber step files and assembly sequence information to LBNL
3.Magnetic structure
Magnetic length:1.5 m (this is the full length of the magnet, including correction coils)
Period length:NbTi – 20 mm
Nb3Sn – 18.5 mm
Magnetic gap:≥ 7.5 mm(not less than 7.5 – could be more if field requirements are met)
Peak magneticfield, Bmax:NbTi – 1.7 T
Nb3Sn – 2.0 T
Superconductor coils cooling:
Indirectly by LHe passing through the channels in the magnetic cores or pipes attached to the magnetic cores.
Tuning system HTS coils: operation temperature is 40 K (?), conduction cooled
Action: Diego/Soren – confirm if 40K is acceptable
4.Quench Protection System
NbTi magnet will continue to use the existing power-supply internal protection system.
Nb3Sn magnet requires adequate space to put protection diodes.
Action: Joel sends file of cryostat layout
5.Cooling system
Type:LHe closed system with He re-condensation in the internal LHe tank
Source of cooling power:cryocoolers
Agreed. LBL will design to be able to attach to flanges on the LHe tank
6.Current leads
NbTi magnet:1 pair of main leads, < 1000 A
2 pairs of correction coil leads, < 100 A
Nb3Sn magnet:1 pair of main leads, < 1000 A
2 pairs of correction coil leads, < 100 A
1 pair of correction coil leads, < 20 A
Field tuning system:1 pair of leads, < 100 A
Action: Yury – send photograph of wiring inside the cryostat
7.Instrumentation ports
As in the SCU0 cryostat.
Additional port(s) are required for field tuning system.
Action: Soren/Diego will provide detailed information re: number of wire pairs needed for the tuning system. Estimate was about 100. Also need the current, static heat load, connector/feedthrough for design purposes.
8.Insulation vacuum
As in the SCU0 cryostat.
Agreed.