# Presentation: 547521

## HTS R&D for High Field Magnets

- 			**Michael Lamm**

**Introduction**
**Examples of Accelerator Magnet R&D with HTS**
**High Field Magnet Design**
**National Collaboration**

**With input from several people at the US National Labs**

- Muon Collider Design Workshop

- 03 Dec 2007

## Interesting Magnets in Muon Colliders

**Colliding Ring/IR  Magnets ~10 T, wide aperture/open midplane**

**From MCTF End of year report**

**“****Low Emmitance” scenario...**

- Muon Collider Design Workshop

- 03 Dec 2007

## Why consider HTS? Thermal Margin.. 

**Superconducting state a function of Jc, Field and Temperature**
**IR and Collider ring and target magnets require high thermal margin at modest fields **
**>10 T on conductor calls for Nb3Sn or HTS materials **

- Muon Collider Design Workshop

- 03 Dec 2007

**Magnets with fields on conductor ~>20T call for HTS**

- Muon Collider Design Workshop

- 03 Dec 2007

## HTS Materials Used in Magnets

**Bi 2223 tape**
- Has been available in long piece lengths from American Superconductor
- Stainless steel reinforced to improve tensile strength
- Significant Angular dependence to Jc (field)
** ****Bi 2212 Round wire**
- Available in long piece length from OST
- No angular dependence
- Better Je than Bi2223
- Can be made into a Rutherford cable
- Wind and react technology....(problems with treatment)

- Muon Collider Design Workshop

- 03 Dec 2007

## HTS Materials Used in Magnets II

**2G YBCO Tape**
- Excellent tensile strain sensitivity
- Significant improvement in Je over Bi 2223 tape
- Jc has strong angular dependence with external field.
- Used in 26T solenoid insert
- Relatively new.... Still being studied

**From Drew Hazelton Presentation at MT 20**

- Muon Collider Design Workshop

- 03 Dec 2007

## HTS Accelerator Magnet R&D in the US

**HEP National Labs study HTS applications in accelerator magnets as part of broader SC magnet R&D Program (Nb3Sn mostly)**
- BNL
- LBNL
- Fermilab
- Muons Inc has worked with FNAL and BNL several topics
- Also work at LANL studying HTS materials
**Studies at the National High Magnetic Field Lab on high field solenoids have applicability to Muon Colliders**

- Muon Collider Design Workshop

- 03 Dec 2007

## LBNL HTS Program

**Emphasis on Bi-2212 Wind and React Technology**
**With SWCC Showa Cable Systems Co. Ltd.**
**Build HTS subscale racetrack coils  from Bi 2212 Rutherford cables. R&D Issues with Bi-2212 W&R**

- Reaction cycle (precise temperature control +/- 2 degrees at >800K)
- Insulation to withstand extreme temperatures
- Important new data on Bi “leakage” issues
**Status: 5 coils manufactured, 3 in progress**

- Muon Collider Design Workshop

- 03 Dec 2007

**Observed at NHMFL as well as HTS vendor:  problem not well understood**

- Muon Collider Design Workshop

- 03 Dec 2007

## BNL Program

**Design/built/test prototype quadrupole for RIA projects**
** ****Expected very high heat deposition (15 kW)**
**Magnets built with Bi2223 tape from American Superconductor, with plans to build YBCO magnets**

**Racetrack coils during assembly**

**Completed 12 Coil magnet**

- Muon Collider Design Workshop

- 03 Dec 2007

## BNL Program

**\**

**Their experience is well suited toward HTS applications in high radiation/energy deposition**

- Muon Collider Design Workshop

- 03 Dec 2007

**New world record for superconducting magnet**

**26.9 T field, **
**>200 MPa hoop stress**

- Muon Collider Design Workshop

- 03 Dec 2007

- Muon Collider Design Workshop

- 03 Dec 2007

## FNAL Program

**Emphasis on HTS cable/strand analysis**
**Two Oxford Instrument Teslatron, capable of testing up to 17 T solenoid field, from 1.9K to 70K **
**Cabling machine**
**Tests performed on Bi 2212 round wire, Bi 2223 tape and YBCO tape**
**Data used in 50 T solenoid paper studies**
**Plans in FY08 to wind small solenoids for Teslatron**

- Muon Collider Design Workshop

- 03 Dec 2007

## HTS and LTS Performance at 4.2 K

- October 30, 2007

**HTS and LTS Performance at 4.2 K**

- Muon Collider Design Workshop

- 03 Dec 2007

## Conductor Testing at Fermilab

**B**

**SAMPLE**

**I**

**B**

**Probe for Angular Measurements**

**Courtesy of E. Barzi**

- Muon Collider Design Workshop

- 03 Dec 2007

## Example of Measurements Performed

**Bi-2223**

**Studies performed on Bi-2223 and YBCO tape (not shown) show Strong angular dependence**

**Studies performed over a wide range of angles, temperatures and fields**

**E. Barzi, SC R&D Lab**
**Supported by Muons Inc..**

**Also extensive temperature and field studies on Bi 2212 wire  inc. effect of cabling on Jc (not shown)**

- Muon Collider Design Workshop

- 03 Dec 2007

## B and T Dependence of Anisotropy

**B and T Dependence of Anisotropy**

**Bi-2223**

**2G 348**

**The B dependence has a linear trend, where the slope value increases with T.**

**No observable T dependence. The ratio saturates at ~7. **

- Muon Collider Design Workshop

- 03 Dec 2007

## Comparison with Super Power 2G

**Comparison with Super Power 2G**

**Ratio saturates, but decreases with temperature**

**I****c****(77K, 0T)=106********1 A**

- Muon Collider Design Workshop

- 03 Dec 2007

## SEM/EDS Cable Surface Analysis

**SEM/EDS Cable Surface Analysis**

**The surface of all the cables after reaction showed black spots embedded in the silver coating.**

**Bi-2212?**

**Bi-2212+MgO?**

**Caused by filament powder leaks**

**For all the cables, tested at self-fields of 0.1 to 0.3 T, an I****c**** degradation of about 50% was measured. This was much larger than the reduction found on the extracted strands. **

- Muon Collider Design Workshop

- 03 Dec 2007

## High Field Magnets Under Study

**Helical Solenoid for Helical Cooling Channel**
- Demonstration Magnet in FY08
- 0.5 M diameter NbTi  6T on conductor
- Channel for Real HCC calls for high field solenoid
**Design Studies for 50 T Solenoids**
- Paper studies performed by Palmer/Kahn et al. and Kashikhin/Zlobin et al
- Published at Pac07/MT20

- Muon Collider Design Workshop

- 03 Dec 2007

## Helical  Solenoid

**Helical  Solenoid**

**The solenoid consists of a number of ring coils shifted in the transverse plane such that the coil centers follow the helical beam orbit.  1) NbTi 4-coil demo 2) MANX expt. 3) multi stage HCC in Muon accelerator (probably HTS in final stage)**

**PAC07 MOPAN117**

**Issues:**
**Mechanical Support**
**Required field quality (construction tolerances)**
**Cryostat**
**Powering and Quench Protection**

- Muon Collider Design Workshop

- 03 Dec 2007

## High Field Solenoid

**Proposed for end of cooling channel for final emittances**
**30-50 T DC, 30-50 mm aperture,  1 m length**
**Goals:  Highest practical field, accelerator field quality, low manufacturing cost, low operating costs**
**Superconducting for manageable power reqs**
- Existing very high field magnets are resistive or resistive/SC hybrids   Megawatt Power, one-of-a-kind, expensive to build/operate
- Engineering current density (Je) of HTS materials measured up to 45 T, have a mild dependence on B... however..
- Building this solenoid is beyond present capabilities, although 25-30T HTS solenoids are proposed, 25 T solenoid inserts demonstrated

- Muon Collider Design Workshop

- 03 Dec 2007

## High Field Solenoid Designs

**Two high field solenoid paper studies related have been performed in the last ~15 months.**
- Parameters
- Hybrid magnet with NbTi, Nb3Sn and HTS superconductor
- Utilize Bi-2223 tapes (steel reinforced, long lengths and reasonable Jc)
- Extrapolate Je to 45-50T using low field angular dependence
- Bi-2212 field Je vs. Field
- Bi-2212 wire is also possible, YBCO not considered (yet)

- Muon Collider Design Workshop

- 03 Dec 2007

## Design Study #1

**From PAC07 MOPAN118 Kahn/Palmer et al**

**Inner diameter set by HTS min bend radius**
**Bi 2223 inner coil, co-wound with SS tape**
**SS thickness adjusted radial to compensate for hoop stress**

**45T Bore Field**

- Muon Collider Design Workshop

- 03 Dec 2007

## Design Issues

**Demonstrated feasibility of HTS/hybrid approach**
**Mitigation of hoop stress through SS tape**
**Need to intercept axial forces**
**Plan to study new YBCO conductor**
**Quench Protection Issues explored:**
**	****Internal Heaters unlikely to work **
**	****Need sensitive quench detection circuitry, probably on every layer of coil, with separate extraction circuits for each layer**

- Muon Collider Design Workshop

- 03 Dec 2007

## Fermilab based study

**Va. Kashikhin et al...**

**Consider two cases:  Minimum Volume/Minimum Cost**

**-Several concentric coils independently supported through SS innertube/outersupport structure.  SS rings sized for expected forces**
**-Coil tension/compression limited to 150 MPa**
**-Requires bonding/no gaps between inner/outer tubes**

- Muon Collider Design Workshop

- 03 Dec 2007

## Minimum Cost

**HTS coils**

**Nb3Sn**

**NbTi **

**Note: “Minimum Radius” eliminates NbTi portion.  **

- Muon Collider Design Workshop

- 03 Dec 2007

## National Collaboration on HTS Magnet R&D

**There is little or no market for HTS materials relevant for high field scientific applications.  **
**From discussion with HTS Vendors, sustained support from magnet community is needed to make progress.   Need effort comparable to successful Nb3Sn Conductor Program**
**Proposal “White Paper” (David Larbalestier, Lance Cooley, Ken Marken and Alvin Tollestrup) to form collaboration among interested National Labs, Universities and HTS vendors to develop program**
**Broad Collaboration of NMR, material science and HEP application interested in  >23 T  at  4 K  and >10 T at 20 K**

- Muon Collider Design Workshop

- 03 Dec 2007

## Collaboration Plans

**Ongoing discussions among the National Magnet Labs and University representatives to define collaboration**
**BNL, FNAL, LANL, LBNL, NHMFL, NIST, TAMU and others...**
**Identify common ground for conductor needs**
**Consolidate existing data on conductor tests**
**Identify facilities and resources**
**Near term and longer term plans for magnet related conductor development and testing, magnet development**
**Proposal for DOE funding has been written **

- Muon Collider Design Workshop

- 03 Dec 2007

## Conclusion

**Several interesting magnet will need to be designed/built at a reasonable cost**
- Need to start development of magnet list/specification
- All reasonable options should be considered
**Active effort on high field magnets in National labs**
- Plans for a “National HTS Conductor Program”  analogous to the existing Nb3Sn program
**Paper studies show feasibility of HTS for 50T solenoids**
- Need to consider 2G-YBCO.  Need more data on angular dependence with field and strain/stress characteristics

- Muon Collider Design Workshop

- 03 Dec 2007