# Presentation: 657647

## Magnet Progress Report

- P. Wanderer
- LARP Collaboration Meeting #10
- April 23, 2008

## Overview

- LQ (3.6 m, cos, 90 mm) quad:
- Progress in magnet construction
- Review of support structure by outside committee (Nov.)
- LRS (3.6 m, no aperture) racetrack:
- Retest with segmented shell support structure
- TQ (1 m, cos, 90 mm) quad:
- New test results (including a test at CERN)
- Related test results in base programs
- 1 m block coils with open ended coils (LBNL)
- 4 m mirror dipole (Fermilab)
- HQ progress (1 m, cos, 130 mm) quad
- Materials Development
- Phase 1 construction project

## LQ Progress (1)

- Schedule:
- LQS01 (LQ with shell support structure) scheduled for test February 2009 (3 months later than planned last June)
- LQ #2 scheduled for test in July 2009 – collar support
- LQ #3 scheduled for test in December 2009.
- Schedule issues:
- Effect of continuing resolution and omnibus budget bill
- Delays in purchasing
- Fermilab staff furloughs
- Continuing DOE support has been of significant help!
- Technical (reaction fixture)

## LQ support structures

- Collar

- Shell

## LQ Progress (2)

- Fermilab will wind, cure, react, impregnate coils:
- Practice coils have been wound, cured, and reacted.
- Reacted coils:  bowed  strengthen fixture against bowing
- Fixture-only (heat) test:  fixture sufficiently straight
- BNL will react, impregnate coils; make shipping fixture
- Fixturing on order, due July
- LBNL will supply support structure (shell):
- Most components on order, some delivered
- Magnet will be tested at Fermilab

## LQ Coil, reaction fixture at Fermilab

## LQ Support Structure at LBNL

- 1m sections of aluminum shell

## LQ support structure review (Nov. 07)

- LQ goal:
- Good quench performance (200 T/m) by end of 2009
- LQ plan – looking for technical flexibility, cost effectiveness:
- First LQ – shell support structure
- Second LQ – collar support structure, using coils from 1st LQ
- Third LQ – TBD
- Review Committee (closeout):
- LQ plan ok
- Concerns:  peak stresses in coil, recent changes in shell support structure, axial loading, strain sensitivity of conductor, schedule

## LRS – long racetrack, shell support structure

- LRS01 – one-piece support structure  sudden changes in strain due to axial slippage of yoke and shell
- LRS02 – segment shell into ~ 1m sections  minor changes in strain

## LRS02 = LRS01 coils in segmented shell supportExcellent quench performance (96% Iss)

## TQ (technology quads) – 1 m, 90 mm, TQC & TQS

- _“__Projectize” LQ (top priority, all $ from LARP budget)_
-  less $ available for TQ
-  support from FNAL, LBNL magnet base programs for new coils, reassembly
-  support from CERN for magnet assembly, testing
- LBNL staff at CERN ... excellent working relationships
-  MUCH APPRECIATED!

## TQS (shell support structure, 1 m, 90 mm)

- _TQS01a, b, c – strand made w. existing (MJR) process (modest J__c__)_
- abc: replace coils that limited performance with new ones
- quench plateau 180 T/m – 200 T/m (4.4 K)
- _TQS02 a, b – strand made w. current (RRP) process (high J__c__)_
- a:  222 T/m (4.4 K), 90% Iss but didn’t advance much at 1.9 K.
- ab: replace two coils (assembly, test at CERN)
- b: 205 T/m, but all quenches in one of the new coils, in the region where the cable was initially wound the wrong way
- plan: strengthen QA; replace coil, test again

## TQC01, TQC01b: strand made w. existing (MJR) process (modest Jc)
	b: replace coils, increase azimuthal preload to design value
	quench plateau (TQC01b): 178 T/m (4.4 K), 200 T/m (1.9 K)

TQC02E (E = exchange:  use coils from TQS02):
	quench plateau at same Iss level as TQS02 at 4.4 K, 1.9 K

TQC02a: new coils, same assembly plan as TQC02E
	(TQC coils slightly different than TQS coils)
	quench plateau 68% Iss (4.2 K, 1.9 K)
	plateau quenches all at one location
	disassembly, inspection of magnet still underway

- 	b: replace coils, increase azimuthal preload to design value
- 	quench plateau (TQC01b): 178 T/m (4.4 K), 200 T/m (1.9 K)
- _TQC02E (E = exchange:  use coils from TQS02):_
- 	quench plateau at same Iss level as TQS02 at 4.4 K, 1.9 K
- _TQC02a: new coils, same assembly plan as TQC02E_
- 	(TQC coils slightly different than TQS coils)
- 	quench plateau 68% Iss (4.2 K, 1.9 K)
- 	plateau quenches all at one location
- 	disassembly, inspection of magnet still underway

- TQC (collar support structure, 1 m, 90 mm)

## Related, recent base program Nb3Sn magnets (1)

- LBNL Dipole
- Block coils with flared ends
- 36mm bore
- 13.3 T Bmax (bore), 14 T Bmax (coil) in 18 quenches
- 87% Iss
- Rebuild/test ongoing

## Related, recent base program Nb3Sn magnets (2)

- Mirror dipole program at Fermilab:
- 	1 dipole coil + iron “mirror” ... close to 2 dipole coils, much less $$
- 	1 m, 2 m, 4 m lengths
- 1 m (HFDM03) and 2 m long (LM01) **PIT** mirror models reached SSL and Bmax ~10 T. Quench performance - practically identical.
- 1 m mirror model (HFDM06) with **1 mm** **RRP 108/127** strand reached 97% of its SSL and Bmax>11 T.
- 4 m mirror model (LM02) **RRP 108/127** reached 87% Iss,
- 	performance limitations:
- 		stress degradation of inner coil near midplane
- 		conductor instability manifested in outer coil

## HQ progress

- _HQ initially_ = high gradient (4 layers) and/or high aperture (2 layers)
- _HQ currently_:
- Focus on high aperture (110, 130 mm)
- Practice winding
- Coil design (LBNL+Fermilab)
- Mechanical design
- 	 – detailed (LBNL)
- Mechanical design –
- 	overview committee
- 	(LBNL, BNL, Fermilab)
- Test 1m model August 09.

## HQ Mechanical analysis

*Courtesy of Vadim Kashikhin*

**HQ Mechanical analysis**
**LQ-based support structure**

- 40 mm Al shell

- 20 mm iron master

- 25 mm Al pad

- Ti poles

- 97 mm iron yoke

- 622 mm = overall diameter

-  Short Sample Gradient ~ 200 T/m
-  Bladder operation : 55 mm bladder pressurized at 50 MPa

## Materials R&D Issues

- Nb3Sn RRP conductor developed to yield current-carrying capacity and magnet stability suitable for 200 T/m, 90 mm aperture quads.  RRP is now a “standard product.”  (US DOE Conductor Development Program, lab core programs helped.)
- Underway:
- Develop larger-diameter strand (for larger diameter magnets)
- Larger-diameter strand requires more, smaller filaments
- Additional work on self-field instability ongoing (+CERN)
- Measure strand Jc vs. strain for RRP 54/61 at NIST (CY08)
- Test cables (as opposed to testing “extracted” strands) at 4.2 K, with varying transverse preload at NHFML (July)

## Increase Subelement Number 

**RRP Strand Development – OST (Fermilab, LARP)**

**114/127 restack with spaced SE’s**
**Jcmax~3000 A/mm****2**** **

**108/127 restack**
**Jcmax~2400 A/mm****2**** **

**54/61 restack**
**Jcmax~3000 A/mm****2**** ****  **

**60/61 restack with spaced SE’s**
**Jcmax********3000 A/mm****2**** **

**Increase Subelement Number**** **

**Increase Subelement Spacing**** **

**RRP1**

**RRP0**

## Magnet Proposal Options for Phase 1 Upgrade

- Phase 1 time frame:  ready to install Dec. 2012
- 	system test starts summer 2012
- _Limited # of Nb__3__Sn quadrupoles for the inner triplet_
- 	“slot compatible” with NbTi quads built by CERN
- 	Nb3Sn demonstration prior to planning for Phase 2 upgrade
- 	technical advantage: larger temperature margin
- 	challenges: time frame, “qualified for accelerators”
- _NbTi dipoles to replace D1 for ATLAS and CMS_
- 	serious candidate:  RHIC DX (180 mm coil aperture)
- _System engineering_
- 	e.g., interface box (room temp to cold) for cryogens, power

## Overall

- _Considerable progress_
- 	3.6 m racetrack performed at ~ 90% conductor limit
- 	1 m cos quadrupoles reach and exceed 200 T/m
- 	on track to test a 3.6 m quad in less than a year
- 	54/61 conductor ok for present magnets (90 mm), but not fully understood
- _Work to do_
- 	most of LQ construction
- 	more measurements of strand and cable properties
- 	continue conductor development
- 	understand 1.9 K performance of quads
- 	understand why some magnets don’t work as well as expected