dipole design at the 16 t frontier - magnet r&d for a future circular collider (fcc) at fermilab...

Dipole design at the 16 T frontier -Magnet R&D for a Future Circular Collider (FCC)

at Fermilab

Alexander ZlobinFermilab

FCC-hh Magnet target parameters

B / G(T) / (T/m)

Bpeak

(T)Bore(mm)

Length(units x

m)

MB 16 16.4 504500 x 14.3

MQ 450 13 50 800 x 6

MQX 225 13 100

D1 12 13 60 4x2 x 12

D2 10 10.5 60 4x3 x 10Inter-aperture distance ≈ 250 mmYoke diameter ≤ 700 mmStray field ≤ 100 mT

2015 FCC meeting Magnet R&D for a Future Circular Collider (FCC) at Fermilab 2

Present record – 13.8 T in ~35 mm aperture (HD2, LBNL, 2008)

FNAL HFM Program

FNAL HFM R&D plan was coordinated with recent P5 recommendations and updated DOE-HEP GARD program• Recommendation 24: “Participate in global conceptual

design studies and critical path R&D for future very high-energy proton-proton colliders. Continue to play a leadership role in superconducting magnet technology focused on the dual goals of increasing performance and decreasing costs.”

In collaboration with the U.S. National laboratories, universities and industry o Develop accelerator magnets with world record parameters

Small-aperture 15 T Nb3Sn dipole, suitable for FCC, and 2 T HTS insert

Large-aperture 15 T Nb3Sn dipole and 5+ T HTS insert with stress management

Small-aperture 20 T accelerator dipole based on LTS (Nb3Sn) and HTS (Bi-2212 or YBCO) coils

o Perform magnet cost optimization studies.o Continue superconductor and structural material R&D for

15-20 T accelerator magnets.2015 FCC meeting Magnet R&D for a Future Circular Collider (FCC) at Fermilab 3

Program Timeline

FY15-17:o Focus on 15 T Nb3Sn dipole demonstrator


VLHC HL-LHCLARP

FCC

Record field 13.8 T

HFDA HFDM-LM 43.5 mm Dipole mirror

10 T dipole

TQC TQM-LQM90 mm 200 T/m Quadrupole

quadrupole mirror

HFDC (R&W)40 mm 10 T dipole

MBHDP 60 mm 11 T dipole

MBHSP MBHSM60 mm 11 T dipole Dipole mirror

Magnet Design Choice

Coil design:o cos-thetao block-type o common coil

Technology: W&R, R&W Mechanical structure:

o with and w/o collaro Stainless Steel or Al

shell o stress management

Field range: 10-13.8 T o 13.8 T - record since

2008

Focus on the cos-theta (shell-type) design w/o collar


MBHSP (FNAL) 11.6 T, 2012-2014

MBHDP (FNAL) 11.5 T, 2015

HFDA (FNAL)10 T, 2003-2006

D20 (LBNL),13.4 T, 1997

HD2 (LBNL),13.8 T, 2008

RD3c (LBNL),10 T, W&R, 2003

DCC017 (BNL), 10 T, R&W, 2007

HFDC (FNAL),~6 T, R&W, 2004

General considerations

Magnet field B ~ λJ×w Bmax~λJc(Bmax,T,…)×w

Small aperture dipole (~50 mm)oQuench protection: Coil enthalpy can absorb the stored energy in <50% of the coil volume with Tmax=250 K

oCoil maximum azimuthal stress is ~150 MPa


Tmax=250 K

150 mm bore

50 mm bore

P. Fessia et al., IEEE TAS, 19, 3, 2009.

1.9 K

Jc(12T,4.2K)=3.5 kA/mm2

Strand and Cable

Strando RRP 127, 169 or 217 o Strand ID – 1 and 0.7 mmo Jc(12T, 4.2K) ~2700 A/mm2

Cableo N=28 (HFDA)o N=40 (MBH)o Ic degradation ~5%o stainless steel coreo cable prototypes are

available R&D

o increase Jc(15 T, 4.2 K)o increase strand D, cable

widtho reduce filament size


RRP-127 RRP-169 RRP-217

Coil Design Study


Coil aperture: 60 mm Coil cross-section: 4 layers, graded Design parameters: Bmax, field quality, coil volume, az. stress Design choice: 4L-5 – minimal coil size and stress

4L-1 4L-2 4L-3 4L-4 4L-5

15 T Dipole Demonstrator

Design concept:• Coil bore: 60-mm • Coil length: 1 m• Optimized design: 4-layer graded coil

• Interim design: with 11 T coil

• Cold iron yoke

Design fields:• Jc(15T, 4.2K)=1.35 kA/mm2

• Coil Bmax= 16.3/15.2 T at 4.3 K

• Bore Bmax= 15.6/14.6 T at 4.3 K

• + ~1.5 T at 1.9 K• Additional margin –

higher Jc


Optimized graded coil

Interim coil design

Mechanical Design

Lorentz forcesHorizontal support

Structure:Thin stainless steel coil-yoke spacerVertically split yoke Stainless steel clampsBolted skin (from 11 T dipole) Cold mass length: 1 mCold mass OD<610 mm (VMTF)

Protection heaters:Outer-layerInter-layer (2-3)Up to 80% of coil volume


Test goals

Demonstration of 15-16 T field level Study and optimization of

o magnet quench performance training, degradation, memory, effect of coil pre-load

o ramp rate sensitivityo operation margino quench protection

heater efficiency, radial quench propagation, coil quench temperature

o field quality geometrical harmonics, coil magnetization, iron saturation, dynamic effects


FNAL 15 T 2-in-1 Demonstrator Parameters

1 m diameter “cryostat” envelope

Number of apertures 2Aperture(mm) 60Aperture spacing (mm) 250Coil current (A) 11100Operating temperature (K) 4.3Max bore field at 4.3 K (T) 16.48Max coil field at 4.3 K (T) 16.96Margin along the load line 0Stored energy (MJ/m) TBDInductance (mH/m) TBDYoke ID (mm) 190.8Yoke OD (mm) 650


Is this magnet good for FCC?

Magnet Cost Reduction

Cost reduction strategy: –Reduce magnet cross-section

– cold mass (coil, structure)

– cryostat

–Increase magnet length– 15 m => 20 m

–Reduce component cost– superconductor (use NbTi

in low fields)– structural components

–Reduce labor– number of coil layers

–Improve performance – Bop, Top


B. Palmer (BNL), 2014

Conclusion

FCC needs cost-effective main dipole magnets with nominal operation fields of ~16 T based on Nb3Sn technologyo Special magnets with operation fields up to 20+ T based

on HTS/LTS coils Timely (by CDR in 2018) demonstration of 16-T-class

accelerator quality dipole for FCC is a key milestone

FNAL has a promising dipole design and a plan to achieve this milestone by 2018o Design Bmax is above 17 T @1.9K with conservative Jco Accelerator quality features

Issues to be understood and resolved for FCCo demonstration of 15-16 T nominal field and accelerator

class parameters, improvement of magnet training, reduction of conductor degradation, magnet cost optimization


Infrastructure

Use the 11 T dipole components, tooling, and FNAL fabrication and test infrastructure => R&D cost and time reduction


dipole design at the 16 t frontier - magnet r&d for a future circular collider (fcc) at fermilab...

Documents