# Presentation: 170599

## High Field Magnet Program Alexander Zlobin

- Magnet Systems Department

- 01/09/2006

## Program goal

**Program goal is the development of next generation SC**** **_***accelerator***_** ****magnets with operating fields above 10 T at 4.5 K and large operation margin.**
**HFM application in HEP:**
- LHC - luminosity and energy upgrades
- Future HEP facilities – ILC IRs, VLHC, Muon SR/collider, etc.
**Fermilab has unique development and test capabilities and infrastructure to perform an efficient accelerator magnet R&D.**
**Complimentary programs:**** **
- U.S. – BNL, LBNL, TAMU
- Europe – CERN, Twente U., Saclay
- KEK?
** **

- Magnet Systems Department

- 01/09/2006

## R&D Activities

**Complex R&D program which includes the following major activities:**** **
- 2D and 3D magnetic design and analysis - maximum field (field range), field quality
- 2D and 3D mechanical design and analysis
- Magnet cooling and heat transfer analysis
- Quench protection design and analysis
- Structural materials studies and selection – SC, insulation, etc.
- Technology development
- Cost analysis and optimization
- Model testing and data analysis
**Wide collaboration inside MSD and TD.**

- Magnet Systems Department

- 01/09/2006

## Superconductor

**Field in present accelerator magnets based on NbTi superconductor is limited by 10T.**
**New generation accelerator magnets use Nb****3****Sn superconductor:**
**Better critical parameters of Nb****3****Sn**** (****B****c2****=27T, T****c****=18K, and J****c****(12T,4.2K)~2.5-3 kA/mm****2****)**
**High-performance Nb****3****Sn strands are commercially available in long length at affordable price**** **
**Alternative superconductors:**
**A15: Nb3Al**
**HTS: BSCCO**
**All these superconductors are brittle **
**need new design and technological approaches. **

- Magnet Systems Department

- 01/09/2006

## Coil Designs and Technology

**Two basic coil designs: **
**shell-type coils with a cos-theta azimuthal current distribution **
**block-type coils **
**Two basic technologies****:**** **
**Wind-and-React (W&R) and React-and-Wind (R&W).**
**Cos-theta and block-type coils with small bending radii**_** require W&R technique**_** **
**Block-type coils arranged in the common coil configuration **_**allow  R&W technique**_

- Magnet Systems Department

- 01/09/2006

## React & Wind Studies

**Four 1-m long R&W magnets (3 racetracks and 1 common coil dipole) were fabricated and tested during 2001-2003:**** **
- All magnets survived the complicate fabrication process and reached 60-70% of the short sample limit.
- The critical current degradation of reacted cable was larger than expected.
- Good, well understood field quality in 2-aperture common coil dipole.
**To realize the potential of the R&W technology for accelerator magnets, significant further efforts are required.**

*FNAL Common coil dipole*

*60—strand cable*

- R&W R&D was stopped in FY2003, resources were redirected to W&R R&D.

- Magnet Systems Department

- 01/09/2006

## W&R Cos-Theta Models

**10-12T Nb3Sn accelerator dipoles based on the cos-theta coil and W&R technique (HFDA).**
**Practical and cost-effective design, and robust technology acceptable for scale up and industrialization.**** **
**The quench performance issues were studied using magnetic mirror (HFDM).**
**New fabrication process to simplify the technology and to reduce the fabrication cost and time:**** **
**ceramic or S2-glass cable insulation with liquid **_**ceramic binder**_** or **_**ceramic pre-preg**_
**metallic end parts made using **_**water jet technology**_
_**half-coil curing**_** at 120C before reaction to obtain a solid coil structure and perform coil size control **

*28-strand cable*

*HFDA dipole*

*Magnetic mirror HFDM*

- Magnet Systems Department

- 01/09/2006

## W&R Summary

**Five 1-m long dipole (HFDA02-06) and five magnetic mirror (HFDM01-05) models made of MJR, RRP and PIT strands were fabricated and tested during 2001-2005: **
**Affordable, robust magnet design and technology were developed and tested**
**MJR and RRP models reached only 50-60% of the expected short sample limit (Bmax~5-7 T) **
**flux jumps due to high Jc and large deff**
**Models made of more stable PIT strand reached the conductor critical current limit (Bmax=10T)**
**Good, well understood field quality**
**a simple and effective passive correction system to correct large coil magnetization effect in Nb****3****Sn accelerator magnets was developed and tested**** **
**Performance reproducibility of main magnet parameters was **_***first time***_** demonstrated for Nb3Sn accelerator magnets**

*HFDA and HFDM Quench performance *

- The objectives of the first phase of HFM Program have been achieved.

- Magnet Systems Department

- 01/09/2006

## Material and Component R&D

**New generation accelerator magnets require advanced superconductors, structural materials and components.  **
**Fermilab developed an infrastructure to perform extensive material R&D in support of the magnet R&D programs: **
- Contribute to National conductor and material development programs sponsored by DOE
- Collaborate with industry on superconductor and material development and characterization

- Magnet Systems Department

- 01/09/2006

## SC Strand R&D

**Study of Nb****3****Sn strands produced using different methods:**
**Internal Tin (IT, RRP) – OST, Supergenics (U.S.)**
**Distributed Tin (DT) – Mitsubichi (Japan)**
**Powder in Tube (PIT) – SMI (Netherland)**
**Study of alternative superconductors:**
**Nb3Al – NIMS (Japan)**
**HTS (BSCCO) – OST (U.S.)**

- Magnet Systems Department

- 01/09/2006

## Cable R&D

**Development and fabrication of Rutherford-type cables using 42-strand cabling machine:**
**Different strand types (Cu, Nb****3****Sn, Nb3Al)**
**Rectangular and keystone x-section**
**Resistive interlayer core**
**Different packing factor**
**One and two stage cables **
**Copper stabilizer **
**Cu tape wrapped on the cable**** **
**Copper core inside cable**
**Cu/SC strand mixing**

*28-strand one stage cable*

*28-strand two stage cable*

- Magnet Systems Department

- 01/09/2006

## Strand and Cable Testing

*Fermilab small racetrack*

**Strand testing performed at Fermilab using SSTF with two Teslatrons.**
**Cable testing performed at Fermilab using SC transformer and Small Racetracks and also at BNL and at CERN. **
**Strand and cable studies include: **
**I****c****(B) and J****c****(B) ******** ****magnet short sample limit**
**M(B)         ******** ****field quality @ low fields**** **
**RRR         ******** ****quench protection**
**current and magnetic instabilities ******** ****quench current limits**
**SEM studies and chemical analysis**
**Strand expansion after reaction        ******** ****technology**
**Heat treatment optimization**

- Magnet Systems Department

- 01/09/2006

## Material R&D Results

**Important results:**
**Study of Nb3Sn strand and cable stability including effect of deff and RRR – magnet performance**
** ****Nb3Sn heat treatment optimization – HT time reduction**
**Cabling degradation studies for different Nb3Sn strands – minimization of Ic degradation, strand improvement**
**Studies of cable sensitivity to transverse pressure – stress limit for different Nb3Sn technologies and magnet designs**
**Study of ceramic insulation and binder – coil fabrication improvement**

- Magnet Systems Department

- 01/09/2006

## LARP Magnet R&D Goals

**The main goal of LARP Magnet R&D is the development of new IR Quads based on Nb3Sn superconductor for the LHC luminosity upgrade:**
- DOE approval in FY2003
- Phase I: Nb3Sn IR Quad technology demonstration in FY2004-2009
**Goals to be reached by the end of FY2009: **
- IRQ target parameters: G~230T/m in 90 mm aperture,
- parameter reproducibility (1-m long technology quads TQ)
- technology scale up (4-m long racetracks LR and quads LQ with TQ cross-section)

- Magnet Systems Department

- 01/09/2006

## LARP Magnet R&D

**LARP magnet R&D includes the following basic directions:**
- technology development (model magnet R&D, supporting R&D, materials)
- IR magnet design studies** **
**The work performed by collaboration of BNL, Fermilab and LBNL**
**Fermilab contributes to all four LARP Magnet R&D activities:**
- Some reproducibility of Nb3Sn magnet performance was already demonstrated by HFDA 10T dipole models. Work will be continued using TQC quad models
- Strand and cable R&D

- Magnet Systems Department

- 01/09/2006

## Technological Quads (TQ) 

- Technological Quads (TQ)

**Model Magnet R&D in FY2005-2007  focuses on technology IR Quads (TQ)**
**Goals: technology development and evaluation of two basic mechanical structures: **
- AL skin/key/SS pads (TQS, LBNL)
- SS collar/yoke/SS skin (TQC, FNAL)
**Design features:**
- 90-mm aperture
- Gmax(1.9K)=230 T/m
- same two-layer shell-type coil design
- same Nb3Sn strand and cable

- Magnet Systems Department

- 01/09/2006

## TQ Fabrication

**Fermilab’s contribution: **
**designed and procured magnet parts; winding, curing, reaction and impregnation tooling**
**provided TQ coil fabrication technology**
**provided strand and strand characterization **
**wound and cured 4 practice and 6 production coils**
**reacted and impregnated 2 practice coils**
**tests mechanical model to verify the results of mechanical analysis and to optimize the assembly process**
**fabrication and test 3 TQC models in FY2006-2007**

- Magnet Systems Department

- 01/09/2006

## Ultimate Gradient Quads (HQ) 

- Ultimate Gradient Quads (HQ)

**Magnet Design Studies in FY2006-2007 are focused on ultimate gradient IR Quads (HQ)**
**Goal:**** **
- reaching the field of 15T
**Design approaches:**
- 4-layer and/or 3-layer shell-type coil
- optimal mechanical structure
- 90-mm aperture
- Gmax(1.9K)=270-310 T/m
**Plan:**
- Coil conceptual design - FY2006
- Concept of mechanical structure - FY2007
- 1-m long models – FY2008-2009

- Magnet Systems Department

- 01/09/2006

## Summary

**Fermilab has sound SC accelerator magnet R&D program which already produced substantial contribution to national and international efforts in the development of new accelerator magnet technologies **
- Development and successful test of two cost-effective 10 T Nb3Sn dipole models for VLHC-stage II provides an important input to strategic planning of national and international HEP Programs
- Studies of Nb3Sn coil magnetization and iron saturation effects on magnet field quality, their compensation using passive correction techniques allows expanded dynamic range of High Field Accelerator Magnets
- Studies and understanding of electromagnetic instabilities in modern Nb3Sn strands and cables and their effect on magnet performance provided guidance for national HFM and Conductor development programs
- Coil fabrication technology was accepted as the baseline technology for LARP IRQ
- Strand and cable measurement methods and techniques form the core of LARP conductor development and characterization

- Magnet Systems Department

- 01/09/2006

## Next Steps

**The main goal of HFM Program in FY2006-2009 is support of LARP Magnet R&D.**
**To reach this goal, HFM Program will focus on:**
**Conductor stability improvement (FY06-07)**
- focus on RRP process (OST)
- collaboration with DOE CDP and industry
**Increase field to ~12-15 T (FY06-08)**
- 11-12 T: 2-layer coil and HFDA mechanical structure
- 12-15 T: 3-4 layer coils and new, stronger structure
**Nb3Sn technology scale up (FY06-07)**
- Prepare infrastructure
- Use HFDM design
- Two steps: 2m and then 4m coil
- Superconductor
- Start with more stable PIT
- Use RRP when stability problem resolved

- Magnet Systems Department

- 01/09/2006

##  Team

- Magnet Systems Department

- 01/09/2006