status on hq coil design and fabrication

Helene Felice11/16/2011

LARP Collaboration Meeting 171st HiLumi Collaboration Meeting

CERN

Status on HQ Coil Design and Fabrication

2

HQ01 series Overview

11/16/2011 H. Felice - 1st HiLumi/ LARP Collaboration Meeting

HQ01a HQ01b HQ01c HQ01d HQ01eCoilsTest

1-2-3-4April 2010

1- 4 -5-6June 2010

1 -5-7-8Oct. 2010

5-7-8-9April 2011

5-7-8-9July 2011

80

90

100

110

120

130

140

150

160

170

180

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Grad

ient

(T/m

)

Quench #

HQ01aHQ01bHQ01c - regular trainingHQ01c - 30 to 50 A/s or profileHQ01d HQ01e

HQ01a – 157 T/m – 79 % Iss – unusual ramp-rateHQ01b – 153 T/m – 77 % Iss – electrical failureHQ01c – 138 T/m – 70 % Iss – unusual ramp-rateHQ01d – 170 T/m – 86 % Iss - mechanical limitHQ01e – 170 T/m – 86 % Iss

9 coils (54/61 or 108/127 RRP) 5 tests at 4.4 K at LBNL

H. Felice - 1st HiLumi/ LARP Collaboration Meeting 3

Overview of HQ01 coil fabrication

11/16/2011

Coil Strand Cable Core Magnet Note

1 54/61 992R No HQ01 a-b-c (LBL) Limiting coil

2 54/61 992R No HQ01 a (LBL) Electrical failure

3 108/127 991R No HQ01 a (LBL) Limiting coil

4 108/127 1000R No HQ01 a-b (LBL)

5 108/127 1000R No HQ01 b-c-d-e (LBL)

6 108/127 1000R No HQ01 b (LBL) Electrical failure

7 108/127 1000R No HQ01 c-d-e (LBL)

8 54/61 996R No HQ01 c-d-e (LBL)

9 54/61 996R No HQ01 d-e (LBL)

10 54/61 996R No Not impregnated Broken strands

11 108/127 (Ti) 1010R No Not tested

12 54/61 1012 SS - 25 mm HQM01 FNAL Special coil

13 54/61 1008 No HQM02 FNAL Special coil


HQ01b Electrical breakdown possible causes

11/16/2011

• Extensive mechanical analysis performed ruled out the participation of the support structure

• Autopsy of coil #6 revealed origin of the short in the interlayer pointed out end design weakness both Lead end and Return end

• Review of the coil fabrication process: high compaction

• Combination of these effects => electrical failure in HQ01b

Lead endView of the return end


High compaction: a common symptom of HQ01 coils

11/16/2011

• 9 coils tested in HQ01 : same observations during fabrication very high compaction after reaction tendency to spring out of the reaction fixture (unlike TQ/LQ)

• Broken strands in coil 10observed post-reaction

Coil 3

Coil 7

Coil 10

• Some corrective actions taken to reduce the compaction

reduction of the radial build-up of material in the cavity

• Coil / cavity size mismatch post reaction? Nb3Sn formation?• Not seen in TQ/LQ


Dimensional changes during heat treatment

Study on unconfined cables

Study on sections of LQ - TQ and HQ coils

ThicknessLQ and TQ: 5.6 and 6% of increaseHQ: only 1 to 2 % of increase

WidthLQ and TQ => 1 to 2 % of increaseHQ => 1 % of increase

Meas. Performed at FNAL D. Bocian, M. Bossert

11/16/2011

width

Meas. performed at LBNL by J. Krishnan

axial contraction: 0.1 to 0.3 % thickness increase: 1.4 to 4 % width increase: 1.5 to 2 %


What is different in HQ?

11/16/2011

• Comparison of the coil fabrication tooling between TQ/LQ and HQ

consistency with a constant cavity size at each step of the fabrication

• Comparison of the coil cross-sections difference in the nominal design insulation

125 mm in LQ 100 mm in HQ

Creating a buffer of 80 mm per turn in LQ ~ 6% of LQ cable thicknessCreating a buffer of 30 mm per turn in HQ ~ 2% of HQ cable thickness

Effective insulation: 86 mm thick

More room in the cavity required for radial and azimuthal expansion


Accounting for axial dimensional changes

11/16/2011

• Axial tension in the conductor ~ 5MPa => Relaxation due to winding tension• Contraction during reaction• Axial gaps in the pole pieces during winding

Axial contraction due to reaction estimated to be 2 to 3 mm/m

Total gap size 3 to 4 mm/m

Winding relaxation estimated to 1mm/m

Modulus vs. Stress for 100lb Cycle

2500

7500

12500

17500

22500

27500

32500

3 13 23Stress (MPa)

Mod

ulus

(MP

a)1000R

1010R1014R5

1014S

1014P1

1014P2

Stress (MPa)

Mod

ulus

(MPa

)

Measured by Brett Collins

Young modulus measured on various HQ unreacted cables:


Test Coils

11/16/2011

Coil 12 – 54/61 – cored cable• By adjusting mid-plane shimming

~3 % per turn of additional space

• Assembled and tested in FNAL HQM01 Limited by mid-plane turn Improved performance at 150 A/s

=> 82 % Iss

“Compaction theory” tested with test coils• Increase of the azimuthal space in the cavity• Still radial compaction

• Unusual coil size => FNAL mirror test

Rodger Bossert & Guram Chlachidze

Coil 13 – 54/61 – no core• By removing the mid-plane turn in both layers

~5 % per turn of additional space Axial gap increased from 0.8 mm to 2 mm

Þ closed after reactionÞ contraction of ~ 3mm/m

• Assembled in HQM02 tested at FNAL 91 % of Iss at 4.6 K 89 % of Iss at 2.2 K


HQ02 coils: reduced compaction

11/16/2011

• A new series of HQ magnets: HQ02

• Main requirement: using the same tooling as HQ01• Interlayer insulation increased to 500 mm • Accounting for dimensional changes and interlayer insulation

Smaller cable with smaller strand => 0.778 mm => 14.8 mm x 1.375 mm Axial gap size 4 mm/m

• All coils made with 108/127 conductor • Revision of the end parts design

• New approach for the magnetic cross-section Reacted cable dimension based on some assumptions

on cable dimensional changes Conductor alignment on the OD of the pole piece


Overview of HQ02 coil fabrication

11/16/2011

Coil Strand Cable Core Status Magnet

14 108/127 1017 No Completed To be tested in mirror

15 108/127 1020B SS / 8 mm / 25 mm Wound & cured To be tested in mirror / HQ02

16 108/127 1020D SS / 8 mm / 25 mm To be tested in HQ02

Coil 14 post-reaction: limited protrusion ~1.5 / 2 mm

Total axial contraction: 3.5 mm/m • Gap: ~4 mm/m • 0.5 mm/m post curing

Coil 15 post-curing:

Total axial contraction: NA• Gap: 4 mm/m • 1 mm/m post curing

Ongoing cored cable measurement to get reference numbers for cored cable dimensional changes


HQ persisting electrical weaknesses

Coil Coil to island Coil to endshoe IL endshoe to OL endshoe Magnet

5 LE – 290 V HQ01 b-c-d-e

7 12.5 kW LE 700-800 V LE – high leakage current HQ01 c-d-e

8 RE – 7.6 kW HQ01 c-d-e

9 RE - 340 V HQ01 d-e

11 Not tested

12 20 kW LE 700-900 V LE – 500 MW HQM01

13 Dead short HQM02

14 LE IL(35 V) / OL (0.5 W) LE – 35 V Not tested

• Despite increased interlayer insulation• Despite outer layer end-shoe revision• Despite reduced compaction

ÞTask force set up to address this issueÞ Possible revision in HQ and LHQ

11/16/2011


Damaged insulation post-reaction

11/16/2011

Insulation fragmentation after reactionPossibly caused by the use of CTD binder

Decision to stop using “precured” glass or Nextel ceramic for the interlayer insulation in the new generation of coils

S-glass placed on the OD of the coil

during reaction (combination of

the brittleness and high

compaction)

Nextel ceramic interlayer insulation, not treated with binder


Summary

• 11 coils fabricated with the HQ01 design Observations: coil high compaction, electrical breakdown, somewhat limited

performance Possible cause of limitations

initial coil design – fabrication process: high compaction

• 2 test coils with reduced compaction tested in FNAL mirror

• HQ02 design implemented in coils 14 and 15 108/127 conductor, smaller cable, OL end-shoe revision Introduction of SS cored cable in all coils starting with coil 15

11/16/2011


Some open questions

• Electrical weaknesses observed in almost all the coils Failure of the hipot coil to metallic components

• Some insulation issues – compatibility with binder

• Some uncertainties about the coil dimensional changes

• Need to understand if the HQ somewhat limited performance come only from the coil high compaction

urgency to get HQ02 coils ready for test

• Ongoing investigation Dimensional changes in cored cables Task force for end-shoe redesign and improvement

11/16/2011

status on hq coil design and fabrication

Documents