HQ coils:
History & Performance
F. Borgnolutti
November 14th 2012
2nd HiLumi Collaboration Meeting
Frascati
Outline
• HQ Coil Design
• Main issues met during HQ coils fabrication
• HQ Coil production summary (coil 1 to coil 20)
• Tests results
• Next generation of HQ coils (starting from coil 21)
• Summary
11/14/2012
HQ Coils: History & Performance
2
HQ Coil Design
Coil main parameters:
• 120 mm aperture diameter
• 1 m long
• 20 turns in L1 / 25 turns in L2
• 87 m of cable/coil
• Cable:
o
o
o
o
o
35 strands
Width = 14.75 mm
Mid-thickness = 1.375 mm
Keystone angle = 0.75 º
Insulation thickness = 100 um
Magnet Expected Performance:
• Short Sample gradient of 214 T/m @ 1.9 K
•
“
“
195 T/m @ 4.4 K
• Nominal Ramp rate 20 A/s
H. Felice et al., “Design of HQ – A High Field Large Bore Nb3Sn Quadrupole Magnet for LARP”, IEEE trans. On Applied Supercond. VOL. 19, NO. 3, JUNE 2009
11/14/2012
HQ Coils: History & Performance
3
Status of the HQ coil production
• From May 2009, 20 HQ Coils have been
fabricated
• 5 tests involving 9 coils (coil 1 to coil 9) have been
performed in a quadrupole structure at 4.4 K
(HQ01a-b-c-d-e )
o HQ01e has been tested a second time (HQ01e-2) at CERN
at both 4.4 K and 1.9 K.
Horizontal “side
shims” are placed here
• 3 tests involving 3 coils (coil 12, 13 and 15) have been
performed at 4.4 K in the mirror structure (individual
coil test, HQM01-02-04)
11/14/2012
HQ Coils: History & Performance
G-10 and
Kapton
midplane shims
Long High-Field Quad
120 mm bore – Length T
Side “ear”
Stainless Skin
Iron Mirror
Block
Iron Yoke
4
Main issues met during the coils fabrication
 Coil expansion/contraction
Coil 3 in the reaction fixture, after reaction
Broken strands in coil 10 (post reaction)
Sign of high radial
compression
Corrective13
actions
COIL
•
Implementation of an axial gap (0.76 mm for coil 3 to 13, 3.2 mm from coil 14)
•
Reduction of the strand diameter from 0.8 mm to 0.778 mm (Starting coil 14)
•
Cable reduced by:
3.8 % azimuthally
2.6 % radially
Some concern
The coils still spring out from the reaction fixture (~2mm, half
of what before making room for cable expansion)

•
Coil springing out of the reaction
fixture
Is the room left for expansion suitable?
Coil 20
The pole gap in coil 17 stayed open


Effect of the braided insulation?
Problem during winding (winding tension)?
11/14/2012
HQ Coils: History & Performance
5
Main issues met during the coils fabrication
 Pole gap in the coils before and after reaction
0.14
IL and OL Pole Gap [inch]
0.12
0.1
L1 Gap after curing
L2 Gap after curing
0.08
GAP L1 after reaction
GAP L2 After reaction
0.06
0.04
0.02
0
13
14
15
16
17
18
19
20
21
Coil #
The pole gap seems optimum since it is at the limit of closing totally after reaction
11/14/2012
HQ Coils: History & Performance
6
Main issues met during the coils fabrication
 Weak electrical insulation between the coil and the coil parts (saddles, spacer,…)
•
•
Recurrent insulation issues between the coil and the parts within the coil
Weak insulation between the coil and the trace (arcing between the trace
and the coil)
Corrective actions
•
Decrease coil compaction and increase insulation
thickness under the trace
•
Starting coil 17: Coating of the coil splice block
and saddles parts ( 5 mils coating thickness)
•
From coil 21: All the parts are fully coated with 10 mils ALO3
coating (10 mils coating thickness, voltage breakdown > 1 kV)
Some concern
•
•
The tolerance we ask for the flat surface of the pole pieces is 9 mils ±1 mil (0.23 mm ± 0.024 mm),
but the tolerance for the pole piece of coil 21 was found between 6 and 9 mils (0.15 - 0.23 mm)
what is acceptable for the field quality?
What happen when the coil is energized and pulls on the coating (debonding?)? Coil 20 could give
an answer..
11/14/2012
HQ Coils: History & Performance
7
Main issues met during the coils fabrication
 Cable mechanically unstable (new issue?)
• Popped strands may cause strand and insulation damages:
o For instance, coil 18 had a lot of inter-turn shorts because of
popped strands
Strands popping out when winding the
L2 (unfavorable winding direction)
• It seems that only the second generation of cable was affected (starting coil 14):
o Smaller strand diameter (from 0.8 mm to 0.778 mm)
o Introduction of a core (8 mm*25 um)
o 2 pass cable (cable fabrication, annealing, re-rolling) to 1 pass cable (strand annealing,
cable fabrication)
Which of these modification contributes to make the cable mechanically less stable?
Maybe a combination of the three…
11/14/2012
HQ Coils: History & Performance
8
HQ Coil production summary
Coil Number
1
2
3
RRP 54/61
4
5
6
7
8
RRP 108/127
9
10
RRP 54/61
11
108/127
(Ti)
1 turn less in L1 &
L2 to provide room
for cable expansion
12
13
15
19
20
108/27
(Ti)
(cable width = 14.75, cable mid-thickness = 1.375 mm,
keystone = 0.75º
Cable with stainless steel core (8 mm*25 um)
L1-RE key fully
Original ends design
Revised end design coated (10 mil)
Wire annealed (185ºC)  cable fabrication
Cable fabrication  annealing (200ºC)  re-rolling (2 pass cable)
All the parts (end saddles, poles pieces, spacers) are left uncoated
11/14/2012
18
3.2-3.3 mm axial pole gap
Cable without a core
H. Felice et al., “Impact of coil compaction on Nb3Sn LARP HQ
Magnet”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE
2012
17
108/127
(Ta)
0.778 mm diameter strand
0.76 mm axial pole gap
Tested in HQ01
16
RRP 54/61 RRP 108/127 (Ta doped)
0.8 mm diameter strand (cable width = 15.15 mm , cable mid-thickness = 1.437mm)
No axial
pole gap
14
Not
tested
Broken
strands
Turn to turn
short
Tested in
Not
mirror
tested
Structure
Good but
not used
HQ Coils: History & Performance
Weak
electrical
insulation
(1 pass cable)
Will be
tested
in
HQ02
Gap did
not close
End saddles are
coated with ALO3Wrong twist
applied to L2
Will not
be used
matrimid
Cyanateester
9
Magnet test results
Limiting coil is underlined
HQ01
HQM
•
•
RRP 54/61
RRP 108/127
Coil
Number
Tested
at
Max gradient
@ 4.4 K [T/m]
% Iss
a
1-2-3-4
LBNL
157
79
Coil 2 damaged (arcing)
b
1-4-5-6
LBNL
153
77
First quench, then
c
1-5-7-8
LBNL
138
70
No training, Intrinsic damage in coil 1
d
5-7-8-9
LBNL
170
86 (4.5 K)
e
5-7-8-9
LBNL
170
86 (4.5 K)
e-2
5-7-8-9
CERN
184 (2.2 K)
85 (4.5 and 1.9 K)
01
12
FNAL
82 (4.6 K)
77 (2.2 K)
Increased azimuthal space made for coil
azimuthal expansion (5.4% / 4.6%)
02
13
FNAL
91 (4.6 K)
89 (2.2 K)
The coil has one turn less in each layer
Azimuthal space (7.6% / 6.3%)
04
15
FNAL
98 (4.6 K)
94 (2.2 K)
Reduced coil compaction (new strand)
Azimuthal space (6.8%/6.8%)
Comment
Pre-load increased wrt HQ01-d
Tested at Cern
S. Caspi et al., “Test results of 15 T Nb3Sn quad. Magnet HQ01 with 120 mm bore for the LHC lumi. upgrade”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012
M. Marchevsky et al., “Quench performance of HQ01, a 120 mm bore Larp quad. For the LHC upgrade”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012
R. Bossert et al., “Optimization and test of 120 mm LARP Nb3Sn quad. Coils using magnetic mirror structure”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012
G. Chlachidze et al., “Test of optimized 120mm Larp Nb3Sn quad. Coil using magnetic mirror structure”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012
11/14/2012
HQ Coils: History & Performance
10
Next generation of HQ coils
6
7
RRP 108/127
8
9
10 11 12 13 14 15 16 17 18 19 20 21
22
23
24
RRP RRP 108/127 (Ta
108/127
Ti
(Ta)
54/61
doped)
(Ta)
?
?
? ?
RRP 54/61
Ti
0.8 mm diameter strand
No axial
pole gap
0.778 mm diameter strand
0.76 mm axial pole gap
3.2-3.3 mm axial pole gap
Cable without a core
Cable with stainless steel core
Original ends design
Revised end design
Cable fabrication  annealing (200ºC)  rerolling (2 pass cable)
All the parts (end saddles, poles pieces, spacers, are left
uncoated
HQ01
25
26
?
?
5
?
4
Delivery July 2013
RRP
54/61
3
Delivery mid-March 2013
2
Delivery January 2013
1
Delivery may 2013
Coil Number
Wire annealed (185ºC) 
cable fabrication
(1 pass cable)
End saddles are All the parts are fully coated
coated with AlO3
(10 mils / 254 um)
HQ02
HQ03
Goal: to have a consistent set of coils for HQ03 and to have LHQ coils consistent with HQ03 coils
11/14/2012
HQ Coils: History & Performance
11
Summary
• The pole gap in the coils allowing longitudinal contraction seems optimized (~3.2 mm)
o The issue of coil 17 (pole gap which did not close) seems to be related to a
mistake made during winding
• Next generation of HQ coils (starting from coil 21) will implement most of the features
of HQ02 coils. In additon they will have:
o All the part fully coated with 10 mils of ALO3 coating
o The coil will be made in a consistent way (the goal is to have all the coils identical)
o We are putting effort in order to get fabrication constitency between HQ and LHQ coils
• We are constantly trying to improve the coil fabrication process:
o Constant evolution of the coil fabrication travelers (tight collaboration between BNL, LBL and FNAL)
o Upgrading and improving the winding tooling (thigh collaboration with FNAL)
•Are the radial and azimuthal room left for expansion suitable?
• There are still unanswered question regarding the coating of the coil parts:
o Acceptable tolerance for the coating thickness to ensure good field quality?
o Unkown regarding the coating to coil interface.
• Cable mechanically unstable:
o Second generation cable is less mechanically stable – several possible causes, need to understand also
also in support of QXF cable
11/14/2012
HQ Coils: History & Performance
12
Back Up Slide 1
 Coil 17 : a mistake made during winding?
Overall length layer 2
before/after Curing
(from RE end saddle to LE splice block)
Overall length coil layer 1
before/after curing
(from RE end saddle to LE splice block)
46.9
46.9
Before L1 curing
46.8
After L2 Curing
After L1 Curing
46.7
length [inch]
length [inch]
46.8
Before L2 curing
46.6
46.5
46.7
46.6
46.5
46.4
46.4
46.3
46.3
46.2
15
16
17
18
19
20
21
46.2
15
coil number
11/14/2012
16
17
18
19
20
21
coil number
HQ Coils: History & Performance
13
Back up slides:
Presentation made by
H. Felice
at the 1st HiLumi collaboration meeting
HQ01 series Overview
Coils
Test
HQ01a
HQ01b
HQ01c
HQ01d
HQ01e
1-2-3-4
April 2010
1- 4 -5-6
June 2010
1 -5-7-8
Oct. 2010
5-7-8-9
April 2011
5-7-8-9
July 2011
180
170

160

9 coils (54/61 or 108/127 RRP)
5 tests at 4.4 K at LBNL
Gradient (T/m)
150
HQ01a – 157 T/m – 79 % Iss – unusual ramp-rate
HQ01b – 153 T/m – 77 % Iss – electrical failure
HQ01c – 138 T/m – 70 % Iss – unusual ramp-rate
HQ01d – 170 T/m – 86 % Iss - mechanical limit
HQ01e – 170 T/m – 86 % Iss
140
130
120
HQ01a
HQ01b
HQ01c - regular training
HQ01c - 30 to 50 A/s or profile
HQ01d
HQ01e
110
100
90
80
0
2
4
11/16/2011
6
8
10
12
14 16 18
Quench #
20
22
24
26
28
30
H. Felice - 1st HiLumi/ LARP Collaboration Meeting
15
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
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
10
54/61
996R
No
Not impregnated
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
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
(LBL)
Electrical failure
(LBL)
Broken strands
16
HQ01b Electrical breakdown possible causes
• 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


Lead end
View of the return end
• Review of the coil fabrication process: high compaction
• Combination of these effects => electrical failure in HQ01b
11/16/2011
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
17
High compaction: a common symptom of HQ01 coils
• 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)


Coil 3
• Broken strands in coil 10
observed post-reaction
• Some corrective actions taken to reduce the
compaction
reduction of the radial
build-up of material in the
cavity
Coil 7

Coil 10
11/16/2011
• Coil / cavity size mismatch post reaction? Nb3Sn formation?
• Not seen in TQ/LQ
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
18
Dimensional changes during heat treatment
Meas. performed at
LBNL by J. Krishnan
Study on unconfined cables
axial contraction: 0.1 to 0.3 %
 thickness increase: 1.4 to 4 %
 width increase: 1.5 to 2 %

Study on sections of LQ - TQ and HQ coils
Thickness
LQ and TQ: 5.6 and 6% of increase
HQ: only 1 to 2 % of increase
Width
LQ and TQ => 1 to 2 % of increase
HQ => 1 % of increase
11/16/2011
Meas. Performed at FNAL D. Bocian, M.
Bossert
width
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
19
What is different in HQ?
• 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
Effective insulation: 86 mm thick
100 mm in HQ



Creating a buffer of 80 mm per turn in LQ ~ 6% of LQ cable thickness
Creating a buffer of 30 mm per turn in HQ ~ 2% of HQ cable thickness
More room in the cavity required for radial and azimuthal expansion
11/16/2011
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
20
Accounting for axial dimensional changes
• Axial tension in the conductor ~ 5MPa => Relaxation due to winding tension
• Contraction during reaction
• Axial gaps in the pole pieces during winding
Modulus (MPa)
Young modulus
measured on
various HQ
unreacted
cables:
Modulus (MPa)
Modulus vs. Stress for 100lb Cycle
32500
27500
1000R
22500
1010R
17500
1014S
1014R5
1014P1
12500
1014P2
7500
2500
3
13
Stress (MPa)
Stress (MPa)
Axial contraction due to reaction
estimated to be 2 to 3 mm/m
11/16/2011
Winding relaxation
estimated to 1mm/m
23
Measured by
Brett Collins
Total
gap
size 3
to 4
mm/m
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
21
Test Coils
“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 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
11/16/2011
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
 closed after reaction
 contraction of ~ 3mm/m
• Assembled in HQM02 tested at FNAL
 91 % of Iss at 4.6 K
 89 % of Iss at 2.2 K
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
22
HQ02 coils: reduced compaction
• 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
11/16/2011
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
23
Overview of HQ02 coil fabrication
Coil
Strand
Cable
Core
14
108/127
1017
No
15
108/127
1020B
SS / 8 mm / 25 mm
16
108/127
1020D
SS / 8 mm / 25 mm
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
11/16/2011
Status
Magnet
Completed
To be tested in mirror
Wound & cured
To be tested in mirror / HQ02
To be tested in HQ02
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
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
24
HQ persisting electrical weaknesses
• Despite increased interlayer insulation
• Despite outer layer end-shoe revision
• Despite reduced compaction
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
Task force set up to address this issue
 Possible revision in HQ and LHQ
11/16/2011
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
25
Damaged insulation post-reaction
Insulation fragmentation after reaction
Possibly 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
11/16/2011
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
26
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
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
27
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
H. Felice - 1st HiLumi/ LARP Collaboration
Meeting
28