Magnetic Shielding for Cryomodules Facility for Rare Isotope Beams (FRIB) MSU, March 6-7, 2013 Reflections by T. Arkan, T. Nicol, and I. Terechkine 3/14/2013MSU Shielding Workshop - Reflections1

Workshop Program Attendees: Jlab(1), FNAL(3), TRIUMF(1), CEA France (1), INFN-LNL(1) KEK Japan (1), Amuneal(1) Yamato Gokin(1) MSU (17) Total: 27 3/14/2013MSU Shielding Workshop - Reflections2

Status of FRIB Development Jie Wei – System Overview:  Dec. 2008: DOE selects MSU to establish FRIB  June 2009: DOE and MSU sign corresponding cooperative agreement  Sept. 2010: CD-1 granted; conceptual design complete & preferred alternatives decided  April 2012: performance baseline & start of conventional facility construction readiness completed  FRIB accelerator is a part of a DOE-SC national user facility with high reliability & availability  Accelerate ion species up to 238 U with energies of no less than 200 MeV/u  Provide beam power up to 400 kW  Satisfy beam-on-target requirements Front End: Installed and tested – Sept Commissioned - March 2017 Cryomodules: Installed an tested – Oct 2018 Commissioned – June /14/2013MSU Shielding Workshop - Reflections3

FRIB Civil Design Completed Close Integration Between Accelerator & Civil Designs 3/14/2013MSU Shielding Workshop - Reflections4

Key Collaborators ANL –Liquid lithium stripper –Beam dynamics verification –β=0.29 HWR design and prototype* BNL –Plasma window & charge stripper, physics modeling, database FNAL –Diagnostics JLab –Cryogenics systems design –QWR & HWR hydrogen degassing –PANSOPHY e-traveler –HWR processing & certification* LANL –Proton ion source, RFQ LBNL –ECR ion source; beam dynamics** ORNL –Diagnostics, controls SLAC** –Cryogenics**, SRF multipacting**, physics modelin g RIKEN - Helium gas charge stripper TRIUMF - Beam dynamics design, SRF, physics modeling INFN - SRF technology KEK - SRF technology IMP - Magnets* Budker Institute, INR Institute - Diagnostics Tsinghua Univ. & CAS - RFQ* ESS - AP* 3/14/2013MSU Shielding Workshop - Reflections5

Status Under Construction In Operation β = 0.53 β = /14/2013MSU Shielding Workshop - Reflections6

β =0.53 Prototype Cryomodule Test Met Goals FRIB Technology Demonstration Cryomodule R&D milestones completed – TDCM operates stably at 2K temperature with excellent cryogenic stability – Cavities continually locked to design frequency; excellent low-level RF control – Coupler operated at full CW power (4.5 kW) in full reflection within specified cryogenic load – Magnetic shielding efficiency demonstrated – Ancillary components (cavity, low-level control, coupler, tuner) operating Lessons learned to benefit the design of FRIB preproduction cryomodules – Team coordination, engineering culture enforcement, magnetic material management, tuner noise, coupler/cavity multipacting, solenoid lead heat load/pressure drop, NSCL cryogenics issues 3/14/2013MSU Shielding Workshop - Reflections7

SRF Infrastructure Heat treatment furnace commissioned at MSU MSU is funding a new “high bay” (~2k m 2, BOD 11/2012) for SRF – 2 cryomodule test caves – 4 vertical test dewars & staging area – Expanded cleanroom & chemistry facility – FPC testing facility – Dedicated SRF cryogenic systems – Heat treatment furnace – Cavity QA facilities VTA CMTF VTA Staging Area FPC Facility Cleanroom & Chem Facility 3/14/2013MSU Shielding Workshop - Reflections8

FRIB Accelerator Systems are on-track with 4/2012 reviewed baseline FRIB appreciate world expert’s advice and recommendations in optimizing the design of technical systems – this time magnetic shielding for cryomodules FRIB is reaching out for motivated physicists and engineers to join the project FRIB welcomes industrial partners to collaborate and participate 3/14/2013MSU Shielding Workshop - Reflections9

10  Magnetic shielding against Earth magnetic field, H res < 15mG Global Shielding or Local Shielding  Reduced fringe field from SC solenoid coil  Materials in the cryomodule, specially vicinity of SC solenoid coil Even SS316L is magnetization problem in the welding Alternative material with reasonable cost K. Saito: magnetic shielding and focusing lens design philosophy Solenoid Bucking coil Cancelation coil Solenoid Iron Flux Return Costly but no magnetization issue if use reliable non- magnetic material for He jacket, components vicinity to SC solenoid coil Less-expensive but magnetization issue of Iron York (~ 2G experienced TDCM) Global shielding scheme (many experienced) Local shielding scheme (less experienced), Use high  at cryogenic Temp., AK4 or Cryoperm Magnetic shielding Less-expensive in shielding cost Reliable shielding Less-expensive SC solenoid coil Workshop on magnetic shielding, 6 March 2013 K.Saito, Slide 10

FRIB QWR 3/14/2013MSU Shielding Workshop - Reflections11 Local cold shield around end resonator Local Cold Shield (Multi-resonator area) Requirement: B < 15 mOe (1.5*10 -6 T)

Shielding Simulations Summary 3/14/2013MSU Shielding Workshop - Reflections12 Global thick single no penetration holes µ -metal Global thick single penetration holes µ -metal Penetration holes for tuner, FPC, support posts, cryogenics piping MaterialThickness [in] Magnetic field [mOe] Local 1-cavity penetration holes w/ hatA4K Local multi-cavity penetration holes w/ hatA4K Local multi-cavity penetration holes w/ hat rail slot. No side rail slot A4K Penetration holes for FPC Penetration holes for header bellow Penetration holes for beam port

Focusing Lens 3/14/2013MSU Shielding Workshop - Reflections13 Beta=0.085 Cryomodule Three types of cryomodules: β = 0.085; β = 0.29; β = 0.53; 9T maximum field 200 mm, 400 mm 500 mm length 40 mm bore I < 100 A 0.12 T x length steering I < 20 A No ferromagnetic materials B < mm

TRIUMF - B. Laxdal Concerns – Interaction of solenoid field on the cavity Promote a quench if field is too high Trap field in case of a quench – Interaction with solenoid field on environment Cause magnetic pollution – Alignment of the solenoid Introduce steering coils to compensate misalignment Need cold position monitor to tune steerers for multiple solenoids 3/14/2013MSU Shielding Workshop - Reflections14

3/14/2013MSU Shielding Workshop - Reflections15

3/14/2013MSU Shielding Workshop - Reflections16

3/14/2013MSU Shielding Workshop - Reflections17

3/14/2013MSU Shielding Workshop - Reflections18

3/14/2013MSU Shielding Workshop - Reflections19

3/14/2013MSU Shielding Workshop - Reflections20

Magnetic Shielding Activities for IFMIF/CEA by Juliette Plouin 3/14/2013MSU Shielding Workshop - Reflections21

IFMIF & SPIRAL-2 : Warm Shield Around the Module Juliette Plouin – FRIB Mag. Shield. Workshop – 6 March IFMIF-EVEDA Cryomodule : 8 HWR, 5 m long According to 2D FEM calculations, it is necessary and sufficient to add a sheet of 1 mm mu-metal as close as possible to the vacuum tank. The many apertures of the cryomodule are critical for the shielding, and overlap of mu-metal sheets are mandatory.  “Preliminary results of the IFMIF cavity prototypes tests in vertical cryostat and cryomodule development”, Orsini and al. Proceedings of SRF 2011

ESS & XFEL: Cold Shield Around the Cavity 23 Calculations were made to evalue a solution with a warm magnetic shield around the cryomodule (which contains 4 cavities) BUT the quantity of need material was a half a ton per module..  Final design : “cold” magnetic shield made of 1,5 mm thick cryogenic material Schematic view of the shield around the cavity for the ESS high beta cavity “Cold” magnetic shield made of 1 mm thick cryogenic material : CRYOPHY from the APERAM society

The LIPAc Cryomodule Due to space charge associated to the high intensity beam, a short, but strong, superconducting focusing magnet package is necessary between cavities. A superconducting option has been chosen based on a cryomodule composed of 8 low- beta Half Wave Resonators, 8 Solenoid Packages and 8 RF couplers. 24 Juliette Plouin – FRIB Mag. Shield. Workshop – 6 March meters

Focusing Lens 3/14/2013MSU Shielding Workshop - Reflections25 Magnet package specifications Integrated on-axis field (solenoid)≥1T·m Integrated gradient (per quadrupole)5 T Steerers field3.5 mT·m Aperture diameter50 mm Flange-to-flange length400 mm Fringe field at the cavity flange (cold)20 mT Working temperature4.4 K Active Shield System 200 mm 400 mm

3/14/2013MSU Shielding Workshop - Reflections26 Magnetic Shielding AU and CF are made of the same high-Ni alloy. AU & BU are prepared by one manufacturer while CF is by another. AU and CF are made of the same high-Ni alloy. AU & BU are prepared by one manufacturer while CF is by another. Material properties are sensitive to heat treatment and to stress

Magnetic Shielding - CEA Measurements performed at room temperature In free air Inside a XFEL vacuum vessel (w/o shield) Inside two different shields (w/o vessel) Cryoperm Cryophy Inside a shield placed inside the vessel Juliette Plouin – FRIB Mag. Shield. Workshop – 6 March Bext/Bint ~25 at room temperature

Magnetic Field B is reduced by the steel vessel alone B is reduced to ~ 2  T with shield alone B is reduced to less than 0,5  T with shield and module Total shielding efficiency (module+magnetic shield) is more than 100 Juliette Plouin – FRIB Mag. Shield. Workshop – 6 March Cryoperm Cryophy !!! ???

3/14/2013MSU Shielding Workshop - Reflections29 Cavity and Fringe Field Interaction by John Popielarski Trying to get results similar to what we obtained at FNAL, including quench annealing.

Magnetic Shield Materials by M. Adolf (Amuneal) Cryoperm-10 vs Amumetal 4K (A4K) ≡ Cryophy 3/14/2013MSU Shielding Workshop - Reflections30 Very sensitive to the heat treatment and the cooling rate. Proprietary data.

Annealing / Handling 3/14/2013MSU Shielding Workshop - Reflections31 Drop test data

Magnetic Shielding Modeling/Design by Ying Xu and M. Shuptar Boundary conditions: – Earth field 0.5 Gauss – Parallel to ground in +x direction ---??? D=20”, t=0.062”, L=100” 3/14/2013 MSU Shielding Workshop - Reflections 32 Design OptionMaterial CostFabricationAssemblyTotal Cost 1/8” µ-metal Shield*$183,504.00$16,000.00$1,800.00$201, X.062” µ-metal Shields*$128,648.64$32,000.00$3,600.00$164, ” A4K Shield (Multi-Cavity)*,**$31,691.00$8,000.00$1,350.00$41, ” A4K +.062” µ-metal Shield *,**, # $95,925.32$24,000.00$4,200.00$124, Dictating Considerations 1.The key cost component of the shield is material cost. 2.According to the simulations a single global shield will need to be 1/8” to meet requirements. 3.µ-Metal cost does not increase linearly with thickness. Meaning as the material doubles in thickness it might triple in cost.

Current Magnetic Shield Sub-System Design 3/14/2013MSU Shielding Workshop - Reflections33 Thermal anchor: Is it enough?

Our Concerns Direction of the global magnetic field is not properly accounted for  magnetic design may not accurate; Material properties of the shielding material accepted for the design may be difficult to get during mass fabrication Temperature of the local shield can be quite uncertain or corresponding time constant can be unacceptably large. 3/14/2013MSU Shielding Workshop - Reflections34