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LARP Magnet ProgramG. Ambrosio

Many slides from (with a few modifications): Jim Kerby for the LARP Magnet Collaboration

25 October 2006

Rad-Hard Insulation WorkshopFermilab – Apr 20, 2007

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Mission Statement:The US LHC Accelerator Research Program enables U.S. accelerator specialists to take an active and important role in the LHC accelerator during its commissioning and operations, and to be a major collaborator in LHC performance upgrades. In particular, LARP will support U.S. institutions in LHC commissioning activities and accelerator science, accelerator instrumentation and diagnostics, and superconducting magnet R&D to help bring the LHC on and up to luminosity quickly, to help establish robust operation, and to improve and upgrade LHC performance. Furthermore, the work we do will be at the technological frontier and will thereby improve the capabilities of the U.S. accelerator community in accelerator science and technology to more effectively operate our domestic accelerators and to position the U.S. to be able to lead in the development of the next generation of high-energy colliders.

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US LHC Accelerator Research Program Magnet Systems

Provide options for future upgrades of the LHC Interaction Regions

Primary Focus: Demonstrate by 2009 that Nb3Sn magnets are a viable choice for an LHC IR upgrade

– The major issues: Nb3Sn technology, consistency, bore/gradient (field), length

– Three phase approach

1. Predictable and reproducible performance

TQ models (1 m, 90 mm aperture, Gnom > 200 T/m, Bcoil > 12 T)

2. Long magnet fabrication

LQ models (4 m, 90 mm aperture, Gnom > 200 T/m, Bcoil > 12 T)

3. High gradient in large aperture

HQ models (1 m, 90+ mm aperture, Gnom > 250 T/m, Bcoil > 15 T)

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Technological Quadrupoles

Two mechanical designs are under development

Same coils / Aperture = 90 mm / Gradient > 200 T/m @ 4.2K

2 layers

FillerKeys

4 pads

Bladder

Yoke

Aluminum shell

YokeGap

PreloadShim

ControlSpacer

Skin

Collar

YokeCollaringKey

Stress Relief Slotin inner pole

TQC: using collarsCollar laminations from LHC-IR quads1st time applied to Nb3Sn coils

TQS: using Al-shellPre-loaded by bladders and keys1st time applied to shell-type coils

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TQ Coil Design and Fabrication

Design features:

• Double-layer, shell-type• One wedge/octant (inner layer) • TQ01: OST-MJR strand, 0.7 mm• TQ02: OST-RRP strand, 0.7 mm• 27-strand, 10.05 mm width• Insulation: S-2 glass sleeve

Winding & curing (FNAL - all coils) Reaction & potting (LBNL - all coils)

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“Baseline Strand”

• Rod Re-Stack Process, RRP 54/61 Design

– 0.7mm diameter

– Filament diameter ~ 70 m

– Jc in the range of 2400-3000 A/mm2 at 12T

– RRR of stabilizer Cu > 100

– low field stability current Is

~ 1000 A and higher depending on reaction time/temperature

126/

127

126/

127

OST-RRP 54/61 design

-600

-400

-200

0

200

400

600

-4 -3 -2 -1 0 1 2 3 4 5 6

APPLIED FIELD [T]

MA

GN

ET

IZA

TIO

N [

kA

/m]

70 m

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Conductor (2)

54/61 RRP conductor is in house

60/61 RRP under evaluation

- larger filament spacing, same Cu/non_Cu ratio (Cu = 47%)

108/127 or 120/127

- More thinner subelements more stable (flux jumps)1.

60/61 restack with spaced SE’s

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S-Glass Sleeve application on Cable

S-Glass sizing removal

S-Glass is baked @ 875 F

Teflon Tube

S-Glass Sleeve

S-Glass: Palmitic Acid application

Insulation Procedure

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Winding & Curing

After winding a ceramic binder is applied (painted) on the coil,the binder is cured at 150 C for 30 minutes (becoming a strong bonding agent),Coils are ready for heat treatment (~650 C in argon)

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Impregnation

Choice of epoxyCTD-101K and EPON828/DMP30 (used in Main Injector Magnets) were tested

CTD-101 K was chosen because:

the pot life is much higher than DMP-30,

very good penetration inside the coil

good mechanical properties

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Goal

By the end of 2009 LARP should deliver a successful Long Nb3Sn Quadrupole

It will be a Proof of Principle that Nb3Sn is a viable option for the LHC luminosity upgrade

In order to have a complete Proof of Principle we will have to address this question:

“Can this magnet withstand the expected radiation dose?”

We should be able to reply either:

“Yes it can, and we have data to demonstrate it”

“No it cannot, but we have tested a TQ with an insulation/impregnation scheme that can withstand the expected dose”

Plan A

Plan B

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Plan A

Identify the most critical parameters of TQ-like magnets that can deteriorate under high radiation dose

– Depending on material and magnet design– Share/tension, swelling, thermal conductivity …

Plan tests of these properties before and after high dose irradiation (a few different doses)

Challenges: – Energy spectrum and dose: reactors, beams (size?), LHC?– Need hot cell?– Need to keep samples cold?

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Plan A possible results

OK, the present insulation/impregnation

scheme can withstand the expected dose We can optimize the

absorbers so that it can withstand the expected

dose

No way,We need a plan B!

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Plan B

Goal: select a material for coil impregnation that can withstand the expected max dose and is compatible with LARP Nb3Sn coil fabrication technology

– Possible candidates: cyanate ester, mixture with epoxy, matrimid, other polyimides…

– Evaluate mechanical, electrical and thermal properties• Literature, cable stack measurement

– Evaluate compatibility with Nb3Sn coil fabrication technology

• Good impregnation, binder compatible, …

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Time frame

Plan A Plan B

FY07 Develop plans, schedule, cost

Select alternative material

FY08

Q1-Q2

Prepare samples and fixtures

FY08

Q3-Q4

Irradiation & tests

Irradiation & tests

FY09 SQ and/or TQ

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Rad-Hard Insulation Workshop AGENDA: 1:30 Introduction 20 G. Ambrosio LARP Magnets Mechanical Analysis 20 I. Novitzky Radiation Environment in the LARP IR Magnets

and Needs for Radiation Tests 30 N. Mokhov

Radiation Effects to Nb3Sn, Copper and Inorganic Materials

20 A. Zeller

3:30 Break 20 Current Knowledge of Radiation Tolerance of

Epoxies 20 R. Reed

Radiation-Resistant Insulation for High-Field Magnet Applications

30 M. Hooker

New Wind-and-React Insulation Application Process

10 M. Hooker

Discussion about test needs, samples, and available test facilities

All

Summary and plans All

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Questions

Develop plan to arrive to these answers:

“Can this magnet withstand the expected radiation dose?”

We should be able to reply either:

- “Yes it can, and we have data to demonstrate it”

- “No it cannot, but we have tested a TQ with an insulation/impregnation scheme that can withstand the expected dose”

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Appendix

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939R

946R

Facet Size Determination

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LR/LM/LQ: Long Magnet Fabrication

Long Racetrack (4m)

– Coil fabrication scale-up based on well-understood sub-scale coils

– Explore length scale-up of coils in shell-based support structure

– LR design complete– BNL practice winding, installation of necessary

tooling underway, oven shipped this week– Tech transfer to BNL w/ SRS01 test successful

Mirror dipole scale-up via FNAL core program

– 2m practice coils under reaction, winding of 2m coils underway 4 m coils to follow

Long quadrupole (LQ)

– 3.6 m quadrupole based on TQ cross-section—initial coils and tooling designs in study

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Beyond TQ: High Gradient Quadrupoles

TABLE II PERFORMANCE PARAMETERS

Parameter Symbol Unit HQ1 HQ2 Short sample gradient* Gss T/m 308 317 Short sample current* Iss kA 10.7 12.6 Coil peak field Bpk (Iss) T 15.6 15.8 Copper current density Jcu (Iss) kA/mm2 2.2/2.2 2.1/2.6 Inductance L (Iss) mH/m 24.5 18.0 Stored energy U (Iss) MJ/m 1.3 1.4 Lorentz force/octant (r) Fr (Iss) MN/m 1.7 1.7 Lorentz force/octant () F (Iss) MN/m -6.0 -6.1 Average coil stress () (Iss) MPa 150 152 Dodecapole (22.5 mm) b6 -0.2 0.0 10-pole (22.5 mm) b10 -0.05 -0.92

(*) Assuming Jc(12 T, 4.2 K) = 3.0 kA/mm2; operating temperature Top=1.9K

HQ1 HQ2

Goals:

• Explore field and stress limits• Feedback to IR optimization

TABLE III LORENTZ STRESS AT 300 TESLA/METER (MPA)

Coil ANSYS (Fig 3) Mid-plane stress: F/(layer width) Design L1&2 L3&4 L1 L2 L3 L4

HQ1 176 167 139 98 179 150 HQ2 178 131 148 143 159 114

The reference cross-sections were selected taking into account stress considerations:

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LHC-IR PrototypeHigh Gradient in a Large Aperture

LHC IR Upgrade Prototype – Aperture: 100-120 mm– Gradient > 200 T/m

– Design will depend on • results form previous parts of

the LARP program• LHC performance in first years• Feedback from AP experts

Example: 4-layer, G=280-310 T/m