TQC Status and Plans

1
TQC Status and Plans
R. Bossert
LARP Collaboration meeting CM-12 April 9, 2009
2
Outline

• Past TQC Models
• TQ Mirror Design
• TQM01 and TQM02
• HQ Mirror Design
• TQC02Eb and TQC03
• Conclusion

3
TQC Models to Date
Magnet Conductor Coils Island Temperature Test
TQC01a MJR (1900 A/mm2) 9, 10, 12, 13 Bronze 4.4 K 1.9K Aug 2006 FNAL
TQC01b MJR 7, 8, 10, 12 Bronze 4.4 K 1.9K May 2007 FNAL
TQC02E RRP (2800 A/mm2) 20, 21, 22, 23 Titanium 4.4 K 1.9 K Nov 2007 FNAL
TQC02a RRP 17, 19, 24, 27 Bronze 4.4 K 1.9 K Jan 2008 FNAL
TQC02b MJR/RRP 10, 12, 17, 19 Bronze 4.4 K 1.9 K Aug 2008 FNAL
Model No. Max SSL at 4.5K Max SSL at 1.9K Max Gradient at 4.5K (T/m) Max Gradient at 1.9K (T/m)
TQC01a 72 87 154 200
TQC01b 86 90 178 200
TQC02E 87 79 201 199
TQC02a 68 65 157 164
TQC02b 85 78 175 173
of SSL in TQC models
4
TQ Mirror - Concept
The magnetic mirror concept was developed
within the FNAL base program, beginning with the
HFM dipole and now expanded to include the
90-120mm quadrupole coils .
Specific coil and cable features can be tested
and optimized efficiently using mirrors.
Mirror fabrication time is short. Completion is
3 weeks from receipt of coil. Only one coil
needs to be fabricated, reducing total time
significantly.
The mirror assembly consists of 2 iron blocks,
one TQ coil and uses standard TQC yoke and
bolt-on skin.
Iron blocks are made of 2 inch thick segments, as
in the dipole mirror design.
5
TQ Mirror Concept
Mirror blocks are manufactured to be identical in
outside dimensions to TQC collar and control
spacer.
Standard TQC ground wrap system is used with
collar-yoke shims and G-10 spacer at midplane.
6
Mirror Magnetic Design
Coil cross-sections of TQC magnet (left) and TQM
(right) with flux density distribution at 14 kA
current.
V. Kashikhin
7
Mirror Magnetic Design
The iron yoke was extended over the coil end,
similar to TQC01b and later models. The magnetic
mirror and spacer were of the same length as the
iron yoke. 3D models indicate that the global
peak field point in the magnet end, as in the TQC
structure.
Mechanical stresses in the coil are also similar
to those in TQC structure and are shown at 300K,
4K and at full field in the Appendix.
V. Kashikhin
8
Magnetic Design - SSL
The estimated magnet quench currents based on the
reference current density of 2800 A/mm2 at 4.5
K and 1.9 K are shown below. This SSL is based
on the mirror magnetic features and the
presentation by Paolo Ferracin, TQ Performance
Overview on Sept. 8, 2008 at the TQ discussion
teleconference. Load lines for these values are
shown on slide 9. The maximum field point in
both cases is located in the outer layer pole
turn of the magnet return end.
SSL in TQS, TQC and TQM structures compared.
Magnet Iss (kA) Iss (kA)
4.3K-4.5K 1.9K
TQM01 (2800 A/mm2) 13.0 14.4
TQS02 (2800 A/mm2) 13.8 15.1
TQC02 (2800 A/mm2) 13.9 15.1
There is also indication from witness samples
(shown in Appendix) that the SSL for the coils
used in TQM01 and TQM02 are lower than the
numbers indicated above.
V. Kashikhin
9
Magnetic Design - SSL
Magnet load lines together with the critical
current curves at 4.5 K (left) and 1.9K (right)
based on reference current density of 2800
A/mm2 (from P. Ferracin talk TQ Performance
Overview Sept. 8, 2008)
V. Kashikhin
10
TQ Mirror Shim System
Assumptions made for analysis to determine shims

• Coil behaves in plastic manner with azimuthal
  MOE of 20 MPa/44 MPa during first pressing and
  subsequent pressings, respectively.
• Final yoked peak preload goal of 120-140 MPa.
• Final cold peak preload goal of 110-130 MPa.
• Specific size of vertical shims based on
  desired preload and measured coil size.
• Shim system shown based on measured size of coil
  19.

11
TQM01
The initial mirror, TQM01, was tested in January
of 2009. It contained Coil 19, an RRP 54/61 coil
with bronze poles that included inner layer pole
slots filled with G-10. Coil 19 had been
previously used in TQC02a and TQC02b, but had not
limited either magnet. Strain gauges were located
at positions positions on the inner surface of
the coil as well as on the inner layer bronze
pole section.
Strain gauge readings during construction are
shown in the Appendix, and indicate that coil
pole gauges reached almost identical values as
TQC02b at 300K (the construction goal).
A conservative approach was taken on TQM01, and
only .004 inches of shim were removed during
yoking, limiting the cold preload to a level
slightly below that shown in the FEA.
Test plan for TQM01 included training and ramp
rate dependence at 4.5K and 1.9K, temperature
dependence studies, manipulation of heaters to
explore instabilities at 1.9K, and thermal margin
studies using mid-plane heaters (similar to but
more extensive that those done on TQC02b).
12
TQM01 Training
Highest quench at 12417A reached over 95 of
reference SSL.
Preliminary quench locations based on Quench
Antenna information only. Preliminary data
indicated that all quenches above 12300 amps were
located in outer layer, at or near the RE (high
field area). Most quenches below 12300 amps in
inner layer pole turn.
13
TQM compared to TQC and TQS
Quench training curves of TQM01, TQC02E and
TQS02a (shown together at left) are very similar.
Coil 19 with bronze poles demonstrated the same
quench performance as the coils with Ti poles.
Ramp rate dependence is less severe in TQM01
compared to TQC, due to lower perpendicular field
component and better cable cooling at midplane.
14
TQM01 test results and TQM02

• Quench plateau of TQM01 reached above 95 of SSL
  with respect to reference SSL, and even higher
  based on witness sample data (shown in Appendix).
  

• Ramp-rate dependence less severe than seen on
  other TQ structures due to lower perpendicular
  field component and better cable cooling in the
  mirror midplane.

• Gauges on inside surface of coil show 30-40 MPa
  decrease in preload during cool-down, expected
  due to the modified shim system used in TQM01.
  End preload bolts remained loaded during
  cool-down and excitation. Skin gauges show 90
  MPa increase during cool-down and slight increase
  during excitation, as expected.

• After training at 4.5K, a short developed
  between one quench protection heater and ground,
  resulting in a discontinuation of the test.

• TQM01 has been disassembled. Coil TQ19 has been
  replaced with coil TQ17, a coil with almost
  identical features and history. The test plan
  for TQM02 will be identical to that proposed for
  TQM01. TQM02 will be tested beginning in
  mid-April.

15
Future Mirrors

• Coils are being fabricated for future mirrors,
  TQM03 and TQM04. Coil 34, shown below, uses
  108/127 conductor and e-glass tape (40-50
  overlap) as cable insulation. It is reacted and
  will be impregnated during the week of April 6th.
  Mirror TQM03 with coil 34 will be tested in May.

• Coil 35, made of 108/127 conductor, includes a
  stainless core and uses the standard S-2 glass
  sleeve as do all other TQ coils. It has been
  wound and cured and is awaiting reaction.

• Both coils include titanium poles.

16
HQ Mirror
The mirror concept can be easily adapted to test
120mm (HQ) coils, the size used for the LHC
upgrade.
Components for the 120mm mirror are being
fabricated using FNAL base program funds.
17
Dipole Style Collar Design

• Traditional vertical collaring uses 4-jaw press
  and quadrupole-symmetric collar laminations.

• Horizontal collaring uses dipole press and
  dipole-symmetric collar laminations.

• Collaring can be done in a single pass,
  eliminating degradation risk and reducing
  construction time.

• Collaring must be done in many passes,
  incrementally. Time consuming process which can
  risk degradation in fragile Nb3Sn coils

18
TQC02Eb and TQC03E

• TQC03Eb will be fabricated using the same set of
  coils previously used for the TQS02 series and
  TQC02E. Stresses and performance will be
  evaluated. If successful, TQC03E and eventually
  LQC01 can be constructed using this collaring
  system.

• TQC03Eb construction will begin as soon as the
  coils are delivered from LBNL. It should be
  completed and tested in June of 2009.

19
Conclusions

• TQC program had demonstrated that the collar
  structure can be used to build successful Nb3Sn
  magnets.

• TQC dipole style collar configuration can
  provide improved reliability and efficiency of
  construction, and can easily be adapted to long
  (for example LQC) structures.

• Specific coil and cable features can be tested
  and optimized efficiently using quadrupole
  mirrors, developed within the FNAL base program.

• TQ mirror provides similar level of field and
  stress distribution as TQ.

• Coil quench performance of mirror is similar to
  that of TQC and TQS.

• Mirror approach can easily be adapted to fit HQ
  coils.

• The mirror structure can provide a very
  efficient way to test long LQ and QA coils.

20
Appendix
The following slides provide additional
information related to the presentation.
21
TQ Mirror Magnetic Design
Figure 1. Horizontal and vertical Lorentz force
components (left) and azimuthal Lorentz force
component (right) of the TQ mirror as functions
of magnet current.
V. Kashikhin
22
TQ Mirror Magnetic Design
The peak field point in the end is in the pole
turn of the outer layer, similar to the original
TQC magnet. Fig. 2 shows the ratio between the
peak field in the end and in the straight section
as function of the magnet current. That ratio is
not constant because of the large iron saturation.
Figure 2. Ratio between the peak fields in the
end and the straight section as function of the
magnet current.
V. Kashikhin
23
TQ Mirror SSL from Witness samples
The magnet short sample limit was estimated
based on the critical current measurements of the
strand witness samples reacted with the coils
17-19 that were made of the same billet (8647).
Table 1 shows the critical currents of three
witness samples measured on Ti barrels and Table
2 shows critical currents of two witness samples
measured on stainless steel barrels. A
least-square fits of the Summers parameterization
of the critical current density for Nb3Sn
superconductor was applied to the measured data,
separately for the Ti and stainless steel
barrels. It resulted in the upper critical field
of Bc2026.70 T and the reference critical
current density at 12 T, 4.2 K of Jcref2428
A/mm2 for Ti barrels and Bc2026.13 T, Jcref2428
A/mm2 for stainless steel barrels. Since there
was no temperature dependence measured on the
witness samples, a theoretical value of Tc018 K
was used. No stress/strain correction was
applied. Fig. 3-4 show the measured data together
with the fitting Summers parameterization at 4.2
K. The magnet quench current was estimated as
an intersection of the critical current curves
with the load lines. Fig. 5-6 show the critical
currents together with the load lines
corresponding to the peak fields in the straight
section and the coil end at 4.5 K and 1.9 K.
The estimated magnet quench currents are 12.461
kA and 13.819 kA at 4.5 K and 1.9 K respectively
based on Ti barrel data and 12.453 kA and 13.817
kA at 4.5 K and 1.9 K respectively based on
stainless steel barrel data. The quench origin in
both cases is located in the outer layer pole
turn of the magnet return end that has the
maximum field point.
V. Kashikhin
24
TQ Mirror SSL from Witness samples
B, T Coil 19 sample 1 Coil 19 sample 1 Coil 19 sample 2 Coil 19 sample 2 Coil 17 sample Coil 17 sample
B, T Ic, A Jc_nonCu, A/mm2 Ic, A Jc_nonCu, A/mm2 Ic, A Jc_nonCu, A/mm2
15 232 1137 268 1314 235 1152
14 288 1412 346 1696 312 1530
13 369 1809 438 2147 392 1922
12 452 2216 537 2633 489 2397
11 562 2755 660 3236 610 2991
10 683 3349 797 3907 749 3672
Table 1. Critical currents of coils 17-19
witness samples measured on Ti barrels at 4.2 K.
B, T Coil 19 sample Coil 19 sample Coil 17 sample Coil 17 sample
B, T Ic, A Jc_nonCu, A/mm2 Ic, A Jc_nonCu, A/mm2
15 237 1162 231 1133
14 314 1539 304 1490
13 402 1971 392 1922
12 504 2471 492 2412
11 621 3045 610 2991
10 756 3706 744 3648
Table 2. Critical currents of coils 17-19
witness samples measured on SS barrels at 4.2 K.
V. Kashikhin
25
TQ Mirror SSL from Witness samples
Figures 3 and 4. Measured critical current
densities and the corresponding fitting function
at 4.2 K for Ti barrels (left) and SS barrels
(right).
V. Kashikhin
26
TQ Mirror SSL from Witness samples
Figure 5. Magnet load lines together with the
critical current curve at 4.5 K based on witness
samples at 2428 A/mm2
V. Kashikhin
27
TQ Mirror SSL from Witness samples
Figure 6. Magnet load lines together with the
critical current curve at 1.9 K based on witness
samples at 2428 A/mm2
V. Kashikhin
28
TQ Mirror SSL from Witness samples
The estimated magnet quench currents based on
witness samples are 12.457 kA and 13.818 kA at
4.5 K and 1.9 K respectively. The quench origin
in both cases is located in the outer layer pole
turn of the magnet return end that has the
maximum field point.
The estimated magnet quench currents based on the
reference current density of 2800 A/mm2 at 4.5
K and 1.9 K are also shown. This SSL is based on
the mirror magnetic features and the presentation
by Paolo Ferracin, TQ Performance Overview on
Sept. 8, 2008 at the TQ discussion
teleconference.
Table 3. SSL in TQS, TQC and TQM structures
compared.
Magnet Iss (kA) Iss (kA)
4.3K-4.5K 1.9K
TQM01 (2428 A/mm2) 12.5 13.8
TQM01 (2800 A/mm2) 13.0 14.4
TQS02 (2800 A/mm2) 13.8 15.1
TQC02 (2800 A/mm2) 13.9 15.1
29
TQ Mirror Magnetic Design
Figures 7 and 8 below present the inductance
(left) and stored energy (right) of TQM01 as
functions of the magnet current. Both values are
approximately ¼ of the original TQ magnet values
at 14 kA current. There is a large non-linearity
in inductance due to the iron saturation.
V. Kashikhin
30
TQ Mirror Structural Analysis
FEA stress plots at 300K, 4.5K and under Lorenz
forces at 14KA, respectively, are shown in
Figures 9, 10 and 11. The examples use the shim
system shown on slide 10, and plastic properties
for the coil.
300K
Figure 9 . TQM01 stresses at 300K.
I. Novitski
31
TQ Mirror Structural Analysis
4K
Figure 10. TQM01 stresses at 4K.
I. Novitski
32
TQ Mirror Structural Analysis
4K, 14kA
Figure 11. TQM01 stresses at 4K, 14kA.
I. Novitski
33
TQ Mirror Structural Analysis
The 2D Finite Element mechanical model of the TQ
mirror is shown at left. It consists of a coil,
an iron mirror with attached iron spacer, top and
bottom iron yoke and stainless skin, an alignment
tube, and is symmetric about the vertical axis.
The coil is modeled as two separate layers glued
together with bronze pole parts. The inner poles
include pole slots with G-10 inserts as exist on
coil 19.
Figure 12. Mechanical Model.
I. Novitski
34
TQ Mirror Structural Analysis
Table 4. Material properties used in Mechanical
Analysis
Structural element Material Thermal contraction (300-4 K), Elasticity modulus, GPa Elasticity modulus, GPa
mm/m Warm 300K Cold 4K
Coil Nb3Sn composite plastic plastic
Azimuthal direction 3.5 44 44
Radial direction 2.6 44 50
Pole Al-Bronze 3.3 110 120
Mirror Soft iron 2.0 210 225
Yoke Soft iron 2.0 210 225
Skin 316L 3.0 210 225
I. Novitski
35
TQM01 Strain Gauges on Coil
The initial mirror, TQM01, contained Coil 19, an
RRP 54/61 coil with bronze poles that included
inner layer pole slots filled with G-10. Coil 19
had been previously used in TQC02a and TQC02b,
but had not limited either magnet. Strain gauge
positions on inner coil surface are shown below.
36
TQM01 Yoking Procedure

1. Assemble coil and mirror into yoke with .019
   total shim placed on top of each vertical
   control spacer. This is .005 inches more than
   the final desired amount.
2. Press magnet in yoke press until coil strain
   gauges bottom out, indicating that the yoke has
   made contact with the control spacers. Verify
   that stresses are as expected (lower than needed
   for final preload).
3. Remove .005 inches of shim and press again until
   strain gauges indicate contact has been made with
   control spacers.
4. Read stress as shown by strain gauges. Continue
   adjusting shims until the appropriate stress in
   coil is reached when contact with control spacers
   has been made. (this was expected to be .014
   inches on TQM01, and was confirmed by the
   assembly).
5. Release press pressure and remove .006 inches of
   shim.
6. Press magnet again until the strain gauges read
   the same values as they did before the shims in
   step 5. were removed. The .006 inch space is
   sufficient to allow the yoke to close onto the
   control spacers during cool-down, maintaining the
   appropriate preload.

Note A conservative approach was taken on
TQM01, and only .004 inches of shim were removed
in step 6, limiting the cold preload to a level
slightly below that shown in the FEA.
37
Strain Gauge Readings during Yoking
Strain gauges were read during yoking. Slides 38
and 39 show readings in strain and stress
respectively. Readings of gauges bonded to
inner surface of the coil near both mid-plane and
pole are shown, as well as gauges bonded to
bronze pole. Red lines on plots show the values
reached by these gauges in TQC02b, for
reference. Data shows that coil pole gauges
reached almost identical values as TQC02b at
300K, mid-plane pole gauges reached a slightly
higher value, while gauges on bronze poles were
lower than in TQC02b.
T
Note Absolute values of bronze pole gauges
mounted on inner poles with slots have not proven
to be reliable in past magnets. However, smaller
numbers in the mirror than in the TQC structure
are predicted by the analysis.
NT
38
TQM01 Azimuthal strain gauge data during yoking
Red lines and strains listed in plot represent
final values read in TQC02b, for reference.
39
TQM01 Azimuthal strain gauge data during Yoking
Red lines in plot represent final assembled
values of TQC02b, and are based on coil MOE of 40
GPa and bronze MOE of 110 GPa.
40
TQM01 Stress Summary
Table 5. Stresses from finite element analysis
for TQM (as designed) and for TQM01 (as built)
Inner pole max Inner pole min Inner pole max Inner pole min
300K 90 105 90 105
4K 75 90 60 70
9kA 35 55 18 40
10kA 30 50 8 30
11kA 18 44 3 25
12kA 14 38 0 15
13kA 6 30 0 0
I. Novitski
41
TQM01 Ramp Rate Dependence at 4.5K
All quenches in the outer coil layer either
middle or return end.
42
TQM01 Heater Ground Short
43
TQM01 Position of Ground Short
44
TQM01 Coil 19 after Test
45
TQM01 Coil 19 after Cleaning
46
List of TQ Coils
This is a list of coils used in TQ magnets, and
the reels from which they came
Coil 001 Practice cable Coil 002 Practice
cable Coil 003 Practice cable Coil 004
Practice cable Coil 005 TQS01, TQS01c, Reel
928 Coil 006 TQS01, Reel 928 Coil 007 TQS01,
TQS01b, TQS01c, TQC01b Reel 928 Coil 008 TQS01,
TQS01b, TQS01c, TQC01b Reel 928 Coil 009 TQC01,
Reel 928 Coil 010 TQC01, TQC01b, TQC02b Reel
928 Coil 011 Practice cable Coil 012 TQC01,
TQC01b, TQC02b Reel 932 Coil 013 TQC01, Reel
932 Coil 014 TQS01b, Reel 932 Coil 015
TQS01b, TQS01c, Reel 928
Coil 016 Damaged, Reel 940 Coil 017 TQC02a,
TQC02b, TQM02 Reel 940 Coil 018 Damaged, Reel
946 Coil 019 TQC02a, TQC02b, TQM01 Reel
946 Coil 020 TQS02, TQC02E Reel 946 Coil 021
TQS02, TQC02E Reel 946 Coil 022 TQS02, TQC02E,
TQS02b Reel 947 Coil 023 TQS02, TQC02E, TQS02b
Reel 947 Coil 024 TQC02a, Reel 946 Coil 025
Tin leaks, Reel 946 Coil 026 Not yet used,
Reel 947 Coil 027 TQC02a, Reel 947 Coil 028
TQS02b, Reel 947 Coil 029 TQS02b, Reel 953
Reels 928 and 932 are MJR. Reels 940, 946, 947
and 953 are RRP.