1
Ramesh Gupta
BNL, NY USA
Rare Isotope Science Project
Institute for Basic Science, Korea
August 23, 2012
Superconducting Magnet Division
Slide No. 2 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Outline
• High Temperature Superconductors (HTS)
• HTS magnet program at BNL
• Benefits of HTS magnets in FRIB (and in RISP)
• HTS Magnet R&D for FRIB
– Phase I (including Energy deposition studies)
– Phase II (including Radiation damage studies)
• Other HTS magnets for FRIB (quad, dipole, corrector)
• HTS magnets for other projects (including 40 T for MAP)
• Summary
Superconducting Magnet Division
Slide No. 3 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnet Technology
Superconducting Magnet Division
Slide No. 4 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Conventional Low Temperature Superconductors (LTS)
and New High Temperature Superconductors (HTS)
Resistance of Mercury falls suddenly
below meas. accuracy at very low (4.2)
temperature
Low Temperature Superconductor Onnes (1911)
Temperature (K)
Re
sis
tan
ce
(O
hm
s)
New materials (ceramics) loose their resistance
at NOT so low temperatures (Liquid Nitrogen)!
High Temperature Superconductors (1986)
Superconducting Magnet Division
Slide No. 5 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Applied Field, T
Jc, A
/mm
2
Another Remarkable Property of HTS The High Field Current Carrying Capacity
R vs. T
HTS
Compare Jc Vs. B
between
conventional Low
Temperature
Superconductors
(LTS) and High
Temperature
Superconductors
(HTS)
Superconducting Magnet Division
Slide No. 6 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Advantages of using HTS in Accelerator Magnets
• HTS based magnets can operate at elevated temperatures
• a rise in temperature from, e.g., decay particles can be tolerated
• the operating temperature doesn’t have to be controlled precisely
• HTS has the potential to produce very high field magnets
As compared to Low Temperature Superconductors (LTS), the
critical current in High Temperature Superconductors falls slowly
• as a function of temperature
• as a function of field
Translate this to magnet design and accelerator operation:
Superconducting Magnet Division
Slide No. 7 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Possible Application of HTS in Accelerator Magnets
High Field, Low Temperature Application
Example: Interaction Region (IR) Magnets for large luminosity
• At very high fields (~18 T or more), no superconductor has as high a critical current
density as HTS does.
Medium Field, Higher Temperature Application
Example: Quads for Rare Isotope Science Project (RISP)
• These applications don’t require very high fields.
• The system design benefits enormously from HTS because HTS offers the
possibility of magnets which operate at a temperature higher than 4K, say at 20-40 K.
• In both cases, HTS magnets can tolerate a large increase in coil temperature with
only a small decrease in magnet performance.
• Moreover, the operating temperature need not be controlled precisely
One can relax about an order of magnitude in controlling temperature variations
HTS allows a few degrees variation, as compared to a few tenth of a degree in LTS.
Superconducting Magnet Division
Slide No. 8 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnet Program
at BNL
Superconducting Magnet Division
Slide No. 9 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnet Programs at BNL (1)
• BNL has been active in developing HTS technology for well
over a decade.
• We have used all types of HTS
– Bi2212 (tape and Rutherford cable)
– Bi2223
– MgB2
– YBCO (Second Generation)
• The size of our HTS program is significant. It can be gauged
by the amount of HTS coming in. We have received or are in
the process of receiving over 50 km of HTS (normalized to the
standard 4 mm tape equivalent) for various programs.
Superconducting Magnet Division
Slide No. 10 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnet Programs at BNL (2)
• Designed, built and tested a large number of HTS magnets:
– Number of HTS coils built: >>100
– Number of magnet structures built and tested: >10
• HTS magnet R&D on a wide range of programs:
– High T, low B
– Medium T, medium B
– Low T, high B
• These varieties of programs help each other in developing a
wider understanding while efficiently sharing resources
Superconducting Magnet Division
Slide No. 11 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
BNL Role in HTS Magnet Development for FRIB
• BNL proposed HTS magnets for FRIB and has been the primary
institution for developing HTS magnet technology for FRIB
• BNL has designed, built and tested 1st and 2nd generation HTS quad
for FRIB
• BNL has carried out energy deposition experiments
• BNL has carried out radiation damage experiments
• BNL is involved in developing variety of HTS magnets for FRIB
(quads, dipoles, correctors)
• BNL is involved in transferring HTS magnet technology to FRIB
Superconducting Magnet Division
Slide No. 12 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Benefits of
HTS Magnets in FRIB
(also in RISP)
Superconducting Magnet Division
Slide No. 13 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Radiation and Heat Loads in
Fragment Separator Magnets
Exposure in the first magnet itself:
Head Load : ~10 kW/m, 15 kW
Fluence : 2.5 x1015 n/cm2 per year
Radiation : ~10 MGy/year
Pre-separator quads and dipole
To create intense rare isotopes, 400 kW beam hits the production target.
Quadrupoles in Fragment Separator (following that target) are exposed
to unprecedented level of radiation and heat loads
Courtesy: Zeller, MSU
Radiation resistant
Superconducting Magnet Division
Slide No. 14 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Technical Requirements
High fields and large apertures require superconducting magnets!
Magnets in the fragment separator target area that survive the
high-radiation environment
• Require that magnets live at least 10 years at full power
• Require refrigeration loads that can be handled by the cryo-
plant
• Require magnets that facilitate easy replacement
Reduced operational costs
• No down time for magnet replacement
• Higher acceptance reduces experimental times
• Robust and resistant to beam-induced quenches
Courtesy: Al Zeller, FRIB/MSU
Superconducting Magnet Division
Slide No. 15 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Possible Technologies for
Fragment Separator Magnets
1. Radiation resistant magnets with copper coils with special
conductor using ceramic or other similar insulator
2. NbTi conventional superconducting magnets with radiation
tolerant epoxy
3. Low temperature superconducting magnets with cable-in-
conduit conductor (CICC), either NbTi or Nb3Sn
4. Radiation resistant and magnets with High Temperature
Superconductor (HTS) that can operate at elevated
temperature and can easily tolerate large energy and radiation
deposition
Detailed investigation gave a surprised answer: Not only HTS provided a technically superior solution, it was also a cheaper solution, when all costs were included
Superconducting Magnet Division
Slide No. 16 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnets in Fragment Separator
HTS magnets in Fragment Separator region over Low
Temperature Superconducting magnets provide:
Technical Benefits:
HTS provides large temperature margin – HTS can tolerate a large local
and global increase in temperature, so are resistant to beam-induced heating
Economic Benefits:
Removing large heat loads at higher temperature (40-50 K) rather than at
~4 K is over an order of magnitude more efficient.
Operational Benefits:
In HTS magnets, the temperature need not be controlled precisely. This
makes magnet operation more robust, particularly in light of large heat loads.
HTS Quad is now the baseline design in the fragment separator of FRIB
Superconducting Magnet Division
Slide No. 17 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Review of the First Generation
HTS Magnet R&D for FRIB
• Demonstration of a HTS magnet built with ~5 km of
~4 mm wide first generation (1G) HTS tape
• Demonstration of stable operation in a large heat
load (energy deposition) environment
Superconducting Magnet Division
Slide No. 18 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
FRIB Quadrupole Design To Minimize Heat Load
Cutout at the middle
of the magnet
Coils inside the cryostat
at the end of the magnet
Coil
Cryostat
(coil inside)
Yoke
(warm iron)
Pole inserts
(warm iron)Coil
Cryostat
(coil inside)
Yoke
(warm iron)
Pole inserts
(warm iron)
Significantly large neutron yield
(radiation load) at small angles
The magnet is designed with warm iron and a compact cryostat to significantly
reduce the amount of cold-mass on which the heat and radiation are deposited.
Quad is designed with two coils (NOT four) to reduce radiation load in ends.
Coils are moved further out to reduce radiation dose.
This design reduces the heat load from ~15 kW to ~0.13 kW on cold structure.
Superconducting Magnet Division
Slide No. 19 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Coil Winding
A coil being wound in a computer
controlled winding machine.
SS Tape
HTS Tape
Earlier coils were
wound with a machine
that has more manual
controls.
Superconducting Magnet Division
Slide No. 20 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Insulation in HTS Coils in High Radiation Environment
Radiation damage to insulation is a major issue for magnets in high radiation area.
Kapton, epoxy and other organic insulation may not be able to survive the
unpredented amount of radiation present in FRIB (or in RISP).
Stainless steel tape (very good insulator as compared to superconductor), being a
metal is highly radiation resistant. SS tape serves as a turn-to-turn insulation.
Superconducting Magnet Division
Slide No. 21 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Design Parameters of 1st Generation HTS R&D Quadrupole for FRIB/RIA
Parameter Value
Aperture 290 mm
Design Gradient 10 T/m
Magnetic Length 425 mm (1 meter full length)
Coil Width 500 mm
Coil Length 300 mm (1125 mm full length)
Coil Cross-section 62 mm X 62 mm (nominal)
Number of Layers 12 per coil
Number of Turns per Coil 175 (nominal)
Conductor (Bi-2223) Size 4.2 mm X 0.3 mm
Stainless Steel Insulation Size 4.4 mm X 0.038 mm
Yoke Cross-section 1.3 meter X 1.3 meter
Minimum Bend Radius for HTS 50. 8 mm
Design Current 160 A (125 A full length)
Operating Temperature 30 K (nominal)
Design Heat Load on HTS coils 5 kW/m3
Superconducting Magnet Division
Slide No. 22 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Magnet Structures for FRIB/RIA HTS Quad (Several R&D structures were built and tested)
6 feet
1.3 m
Mirror Iron
Return YokeIron Pole
HTS Coils
in Structure
Mirror cold iron
Mirror warm iron
Superconducting Magnet Division
Slide No. 23 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Assembled Coils with Internal Splice
Three pairs of coils during their assembly a support structure.
Superconducting Magnet Division
Slide No. 24 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
LN2 (77 K) Test of Coils Made with ASC 1st Generation HTS
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10 11 12 13
Coil No.
Cu
rre
nt
(@0
.1 m
V/c
m) Single Coil Test
Double Coil Test
Note: A uniformity in performance of a large number of HTS coils.
It shows that the HTS coil technology has matured !
13 Coils made HTS tape in year #1 12 coils with HTS tape in year #2
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10 11 12
Double Coil Test
Coil No.
Each single coil uses ~200 meter of tape
Superconducting Magnet Division
Slide No. 25 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Mirror Model Test Results (operation over a large temperature range)
A summary of the temperature dependence of the current in two, four, six and twelve coils in
the magnetic mirror model. In each case voltage first appears on the coil that is closest to the
pole tip. Magnetic field is approximately three times as great for six coils as it is for two coils.
More coils
create
more field
and hence
would have
lower
current
carrying
capacity
0
50
100
150
200
250
300
0 10 20 30 40 50 60 70 80 90 100
Tempratue (K)
Cu
rre
nt
@ 0
.1 m
V/c
m (
A)
Two Coils
Four Coils
Six Coils
Twelve Coils
Superconducting Magnet Division
Slide No. 26 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Full Model Test Results (operation over a large temperature range)
0
50
100
150
200
250
300
0 10 20 30 40 50 60 70 80 90 100
Tempratue (K)
Cu
rre
nt
@ 0
.1 m
V/c
m (
A)
Series I coils (older, in mirror configuration)
Series II coils (newer, in full magnet)
Newer (series II) conductor was not only better at 77 K but also
had relatively better performance at lower temperature.
Superconducting Magnet Division
Slide No. 27 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Energy Deposition Experiments
• Energy deposition experiments were carried out at different
operating temperature.
•The amount of energy deposited on the HTS coils is controlled by
the current in heaters placed between the two coils.
Stainless steel tape
heaters for energy
deposition experiments
Superconducting Magnet Division
Slide No. 28 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Energy Deposition Experiment During Cool-down at a Constant Helium Flow-rate
Note: HTS coil remained superconducting during these tests when
operated somewhat below the critical surface.
Energy Deposition Experiments
at a flow rate of 135 standard cubic feet per hour
28
28.5
29
29.5
30
30.5
31
160 180 200 220 240 260 280
Time (minutes)
Tem
p (
K)
Heaters at
19.4 Watts
Heaters at
29.4 WattsSteady state at
~26 W (estimated)
Heaters between HTS coils were turned on while the magnet was cooling
with a constant helium flow rate of 135 standard cubic feet (SCF)
Temperature decreased
at 19.4 W
Temperature increased
at 29.4 W
Heat load for steady
state ~26 Watts
Superconducting Magnet Division
Slide No. 29 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Large Energy Deposition Experiment
Magnet operated in a stable fashion with large heat loads (25 W, 5kW/m3)
at the design temperature (~30 K) at 140 A (design current is 125 A).
Sta
ble
op
erati
on
for
~40
min
ute
s
Voltage spikes are related to the noise
Superconducting Magnet Division
Slide No. 30 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Review of the Second Generation HTS Magnet R&D for FRIB
• HTS magnets with significant quantities of 12 mm wide
2G tape from two vendors (SuperPower and ASC)
~9 km equivalent of 4 mm tape
• Radiation damage test in high radiation environment
Superconducting Magnet Division
Slide No. 31 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Why 2G HTS
• Allows higher gradient at higher operating temperature
15 T/m instead of 10 T/m
40-50 K operation rather than ~30 K
• Conductor of the future
Projected to be less expensive (uses much less silver)
and have better performance
Superconducting Magnet Division
Slide No. 32 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Para
mete
r List
Parameter Value
Pole Radius 110 mm
Design Gradient 15 T/m
Magnetic Length 600 mm
Coil Overall Length 680 mm
Yoke Length ~550 mm
Yoke Outer Diameter 720 mm
Overall Magnet Length(incl. cryo) ~880 mm
Number of Layers 2 per coil
Coil Width (for each layer) 12.5 mm
Coil Height (small, large) 26 mm, 39 mm
Number of Turns (nominal) 110, 165
Conductor (2G) width, SuperPower 12.1 mm ± 0.1 mm
Conductor thickness, SuperPower 0.1 mm ± 0.015 mm
Cu stabilizer thickness SuperPower ~0.04 mm
Conductor (2G) width, ASC 12.1 mm ± 0.2 mm
Conductor (2G) thickness, ASC 0.28 mm ± 0.02 mm
Cu stabilizer thickness ASC ~0.1 mm
Stainless Steel Insulation Size 12.4 mm X 0.025 mm
Field parallel @design (maximum) ~1.9 T
Field perpendicular @design (max) ~1.6 T
Minimum Ic @2T, 40 K (spec) 400 A (in any direction)
Minimum Ic @2T, 50 K (expected) 280 A (in any direction)
Nominal Operating Current ~280 A
Stored Energy 37 kJ
Inductance ~1 Henry
Operating Temperature 50 K (nominal)
Design Heat Load on HTS coils 5 kW/m3
Superconducting Magnet Division
Slide No. 33 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Magnetic Design
Neck
Ne
ck
Uses 12 mm tape rather than 4 mm tape
Benefits of 12 mm Tape:
• Minimizes the number of coils and joints
• Current is higher (inductance is lower)
• Relative impact of local weak micro-spot less
Superconducting Magnet Division
Slide No. 34 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Cryo-mechanical Structure
Cryosta
tSS Clam
ps
CoilsH
e
Lin
e
Cryosta
tSS Clam
ps
CoilsH
e
Lin
e
R&D Magnet in cryo-stat
(allows independent testing of
four HTS coils)
Warm Iron
Cut-away isometric view of the
assembled magnet
(compact cryo design allowed larger space
for coils and reduction in pole radius)
Superconducting Magnet Division
Slide No. 35 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Winding of Second Generation HTS Racetrack Coil for FRIB
Two vendors:
ASC and
SuperPower
Superconducting Magnet Division
Slide No. 36 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Coils Made with ASC HTS
~210 m (~125 turns), 12 mm
double HTS tape per coil.
One coil was wound
without any splice
Superconducting Magnet Division
Slide No. 37 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
FRIB Coil Made With SuperPower Tape
SuperPower coil uses ~330 m 2G tape (~213 turns) per coil.
Fully wound coil with SuperPower tape with one splice
Superconducting Magnet Division
Slide No. 38 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Coils Assembled in Quadrupole Support Structure
Superconducting Magnet Division
Slide No. 39 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Quad in Unique Cryostat
Superconducting Magnet Division
Slide No. 40 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Yoke Iron for FRIB Quad
Superconducting Magnet Division
Slide No. 41 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Aperture of 2G HTS Quad for FRIB
Superconducting Magnet Division
Slide No. 42 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Completed 2G HTS Quad for FRIB
Superconducting Magnet Division
Slide No. 43 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Proud Team Members
Superconducting Magnet Division
Slide No. 44 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
77 K Test Results of an Individual Coil
0
1000
2000
3000
4000
5000
6000
7000
8000
0 20 40 60 80 100 120 140 160 180 200 220
Co
il V
olt
ag
e(m
V)
Current (A)
Measurement in liquid nitrogen (~77 K) of critical
current in FRIB coil (large, outer, 126 turns made with
~210 meter tape from American Superconductor
Corporation). The critical current in coil with 0.1 mV/cm
definition (total coil voltage 2100 mV) is 193.4 A.
Superconducting Magnet Division
Slide No. 45 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Performance of SuperPower Coils (four of eight coils powered)
Field on SuperPower
coils at 100 A
Ic defined at 0.1 mV/cm
Four ASC coils were
not powered
Internal splice on wrong tape side shows higher resistance.
This is not an operational issue as the heat generated is
negligible as compared to the energy deposition.
Industry standard 1 mV/cm
Superconducting Magnet Division
Slide No. 46 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Performance of ASC Coils (four coils of eight powered)
Field on ASC coils at 100 A
ASC Tape:
2 plies of HTS
and 2 plies of Cu
Ic defined at 0.1 mV/cm
Four SuperPower coils not powered
Superconducting Magnet Division
Slide No. 47 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
77 K Test in Quadrupole Mode (all eight coils powered)
Currents used in quadrupole mode test at 77 K
SP ASC
40 69.3
50 86.7
60 104
Design: SuperPower coils ~172 A and ASC coils ~300 A (at 40-50 K).
Coils reached over 1/3 of the design current at 77 K itself.
Extrapolation to 40-50 K indicates a significant margin (next slides).
Field with ASC coils at 200A and
SuperPower coils at 115.5 A
Actual 40 K test is expected in a few months.
Superconducting Magnet Division
Slide No. 48 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Quench Protection in FRIB HTS Quad
• Quench protection of HTS coils (particularly at 4 K where current densities are high) is
considered a major challenge in light of low quench velocities
• To overcome these challenge, an advanced quench protection system with fast
electronics and low noise has been developed.
• Modern data acquisition and processing system is also developed.
• A number of v-taps are installed in the coil to detect quench in small sections.
• As such quench protection in HTS magnets for FRIB is much less of an issue as
compared to that in other HTS magnets. This is because of the fact that operating
current is much lower at 40-50 K (instead of 4 K), and therefore, the current densities in
copper (hence temperature rise) is much lower.
Superconducting Magnet Division
Slide No. 49 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Quench Protection Studies in FRIB
2G HTS Coils
ASC YBCO Coil (with nano-dots)
SP YBCO Coil (without doping)
ASC BSCCO Coil (1st series)
0
100
200
300400
500
600
700
800
900
10001100
1200
1300
1400
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Temp (K)
Je, A
/mm
2 (
0.1
mV
/cm
)
ASC YBCO Coil
ASC Bi2223 Coil
SP
YBCO
Coil
• Experimental studies were performed as a function of temperature to see
what happens when coil go normal (due to quench, thermal runaway, etc).
Coils with very high current density in copper at quench survived:
~1500 A/mm2(ASC); ~3000 A/mm2(SuperPower)
FRIB design is more conservative (low risk, large margin for real machine):
Current density in Cu is much lower: ~300 A/mm2 (ASC) or ~700 A/mm2 (SP)
0
50
100
150
200
250
300
350
400
450
500
550
600
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
I c, A
(0
.1 m
V/c
m)
Temp (K)
ASC YBCO Coil (with nano-dots)
SP YBCO Coil (without doping)
ASC BSCCO Coil (1st series)
ASC YBCO Coil
ASC Bi2223
SP YBCO Coil
Superconducting Magnet Division
Slide No. 50 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Radiation Damage Experiments
Superconducting Magnet Division
Slide No. 51 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Radiation Damage Studies at BLIP
The Brookhaven Linac Isotope Producer (BLIP) consists of a linear
accelerator, beam line and target area to deliver protons up to 200 MeV energy
and 145 µA intensity for isotope production. It generally operates parasitically
with the BNL high energy and nuclear physics programs.
From a BNL Report (11/14/01)
Superconducting Magnet Division
Slide No. 52 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Key Steps in Radiation Damage Experiment
142 MeV,
100 mA protons
Superconducting Magnet Division
Slide No. 53 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Samples Examined
• Samples of YBCO (from SuperPower and ASC), Bi2223 (from
ASC and Sumitomo) and Bi 2212 (from Oxford) were irradiated.
• This presentation will discuss the test results of YBCO only.
• Twenty samples were irradiated – 2 each at five doses (1016, 1017,
2 x 1017, 3 x 1017 and 4 x 1017 protons/cm2) from both vendors.
• 1017 protons/cm2 (25 mA-hrs integrated dose) is equivalent to over
15 years of FRIB operation (the goal is 10 years).
Superconducting Magnet Division
Slide No. 54 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Relative Change in Ic due to Irradiation of SuperPower and ASC Samples
Radiation Damage Studies on YBCO by 142 MeV Protons
by G. Greene and W. Sampson at BNL (2007-2008)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
0 25 50 75 100 125
Radiation Dose (mA.Hours)
I c (Ir
rad
iate
d)
/ I c
(O
rig
inal)
SuperPower Sample#1
SuperPower Sample#2
SuperPower Average
ASC Sample#1
ASC Sample#2
ASC Average
100 mA.hr dose is ~ 3.4 X 1017
protons/cm2 (current and dose scale linearly)
Ic Measurements at 77 K, self field
Ic of all original (before irradiation) was ~100 Amp
Ramesh Gupta, BNL 3/2008 Su
pe
rPo
wer
an
d A
SC
sa
mp
les
sh
ow
ve
ry
sim
ilar
rad
iati
on
dam
ag
e a
t 77 K
, self
fie
ld
Superconducting Magnet Division
Slide No. 55 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
~ 1.7 X 1017
protons/cm2
Ic (1mV/cm) as a function of temperature
T (kelvin)
I c (
A)
@1m
V/c
m
~ 3.4 X 1017
protons/cm2
Change in Critical Temperature (Tc) of YBCO Due to Large Irradiation
Before Irradiation
• Radiation
has an impact
on the Tc of
YBCO, in
addition to
that on the Ic.
• However,
the change in
Tc is only a
few degrees,
even at very
high doses.
Superconducting Magnet Division
Slide No. 56 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Measurements of Radiation Damage in Presence of Field
1
90
1
89
0.00
10,000.00
20,000.00
30,000.00
40,000.00
50,000.00
60,000.00
arbitrary
intensity
scale
mm below tab
mm E towards tab
Foil Irradiation Surface Plot
50,000.00-60,000.00
40,000.00-50,000.00
30,000.00-40,000.00
20,000.00-30,000.00
10,000.00-20,000.00
0.00-10,000.00
Tab ->
(Up) East
West
Down
Voltage taps
I
HTS sample
is under the
G-10
cover
Voltage taps
I
Voltage taps
I
HTS sample
is under the
G-10
cover
A B C
B
TOP VIEW
B
TOP VIEW
B
TOP VIEW
B
TOP VIEW
B
TOP VIEW
B
TOP VIEW
Field angle
is zero here
Superconducting Magnet Division
Slide No. 57 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Radiation Damage from 142 MeV protons in SP & ASC Samples (measurements at @77K in 1 T Applied Field)
0
5
10
15
20
25
30
0 30 60 90 120 150 180 210 240 270 300 330 360
Ic (
A)
Field Angle (degrees)
Ic Measurements of SuperPower Samples at 77 K in bacground field of 1 T
B_2.5 B_25 B_100
B_100
B_2.5
B_25
~1 year
>15 years
>60 years
0
5
10
15
20
25
30
0 30 60 90 120 150 180 210 240 270 300 330 360
Ic (A
)
Angle (degrees)
Ic Measurements of ASC at 77K in background field of 1T
B_2.5 B_25 B_100
> 1 year
> 15 year
> 60 year
0
5
10
15
20
25
30
0 25 50 75 100 125
Ic(m
in),
Ic(m
ax),
Am
p
Dose (mA-hours)
Ic Measurements of SuperPower and ASC at 77K in field of 1T
Imin(SP)
Imax(SP)
Imin(ASC)Imax(ASC)
SuperPower
ASC
SuperPower
ASC
Minimum
and
maximum
values of Ic
are
obtained
from the
graphs on
the right
• While the SuperPower and ASC samples
showed a similar radiation damage pattern in
the absence of field, there is a significant
difference in the presence of field (particularly
with respect to the field angle).
• HTS from both vendors, however, show
enhancement to limited damage during the
first 10 years of FRIB operation (good news)!!!
Superconducting Magnet Division
Slide No. 58 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Other HTS Magnets
in FRIB/RISP
Superconducting Magnet Division
Slide No. 59 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnets in FRIB/RISP
• HTS offers a unique magnet solution for challenging fragment
separator environment of FRIB.
• HTS is the baseline design for fragment separator quad Q1.
• HTS is also being seriously considered for fragment separator
dipole and corrector magnets.
• BNL has already working on aspects of these magnets with
funding from FRIB and from other governmental agencies.
HTS magnets can be also be used in a large number of other
magnets in FRIB or RISP.
Superconducting Magnet Division
Slide No. 60 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Dipole for Fragment Separator
Muons,
Inc.
High Radiation Environment Nuclear Fragmentation
Separator Dipole Magnet
Stephen A. Kahn1 and Ramesh C. Gupta2 1Muons, Inc., Batavia, IL 60510, 2Brookhaven National Laboratory,
Upton, NY 11973
From IPAC2012 Paper
Pre-separator quads and dipole
Superconducting Magnet Division
Slide No. 61 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Dipole for FRIB with Curved Coil
Muons,
Inc.
From IPAC2012 Paper
FABRICATION AND TESTING OF CURVED TEST
COIL FOR FRIB FRAGMENT SEPARATOR DIPOLE*
S.A. Kahn, Muons, Inc., Batavia, IL 60510, U.S.A.
J. Escallier, R.C. Gupta, G. Jochen and Y.
Shiroyanagi, BNL, Upton, NY 11973, U.S.A.
Superconducting Magnet Division
Slide No. 62 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Corrector for FRIB
Muons,
Inc.
RADIATION TOLERANT MULTIPOLE CORRECTION COILS FOR FRIB QUADRUPOLES*
S.A. Kahn#, Muons, Inc., Batavia, IL 60510, U.S.A.
R.C. Gupta, BNL, Upton, NY 11973, U.S.A.
From IPAC2012 Paper
Funding from FRIB for initial R&D and request for funding from other sources
Superconducting Magnet Division
Slide No. 63 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
Cryo-cooler based HTS Magnets (an alternate option for FRIB and elsewhere)
Cryo-cooler based HTS
magnet option offers an
alternative to Helium
based cryo-system.
• Coils reached <40 K
overnight with cryo-
coolers
• 25 W heat load at 50 K
can be removed by a
number of cryo-coolers
Superconducting Magnet Division
Slide No. 64 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
HTS Magnets can be used at
several other places in FRIB/RISP
Superconducting Magnet Division
Slide No. 65 Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL RISP, ISB, Korea, August 22, 2012
High Field HTS Magnet
Test Results
Superconducting Magnet Division
Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL Slide No. 66 RISP, ISB, Korea, August 22, 2012
High Field Solenoid (~35 T) R&D for Muon Accelerator Program (with PBL)
• A hybrid design with HTS inserts and LTS outsert(s) to generate ~35 T field
• 38 HTS pancake coils have been built and individually tested at 77 K
• Record field (>15 T) achieved in HTS insert#1
• Record conductor (1.2 km) used in high field 4 K application in ½ HTS insert #2
• Full insert#1 + Full insert#2 to be tested soon with a target field of over 20 T
• Major challenges: Large stresses, quench protection, new material.
~55 mm
~64 mm
½ midsert insert
1 2
3
Superconducting Magnet Division
Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL Slide No. 67 RISP, ISB, Korea, August 22, 2012
• Field on axis: over 15 T
• Field on coil: over 16 T
• Highest field in an all HTS solenoid
(previous best SP/NHMFL ~10.4 T)
• Overall Jo in coil: >500 A/mm2 at 16 T
14 pancake coils with ~25 mm aperture
Test stopped at 285 A
High Field HTS Solenoid Test Results
HTS Coil #1
0
25
50
75
100
125
150
175
200
225
250
275
300
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Cu
rre
nt
(A)
Temp(K)
Peak Field on Coil at 250 A : ~9.2 T
Coil operated with margin at 250 A
PBL/BNL 100 mm HTS Solenoid Test for Muon Collider
12 pancake coils with ~100 mm aperture
• Field on axis: 6.4 T
• Field on coil: 9.2 T
• Test stopped at 250 A to protect electronics
• Largest use of HTS (1.2 km) in a high
field HTS magnet operating at 4K
• Full magnet will generate over 10 T and
use 2.4 km conductor in 24 pancakes
HTS Coil #2
Superconducting Magnet Division
Superconducting Magnets for Particle Accelerators Ramesh Gupta , BNL Slide No. 68 RISP, ISB, Korea, August 22, 2012
Summary
• HTS offers a unique magnet solution for challenging fragment
separator environment of FRIB and RISP.
• In addition to fragment separator, HTS magnets could be
beneficial in several other regions.
• R&D for FRIB has demonstrated that HTS magnets can be
successfully built using a large amount of HTS
• It has been demonstrated that HTS can be reliably operated at
elevated temperatures in presence of large heat loads.
• Experiments show that HTS is robust against radiation damage.
• FRIB or RISP could be the 1st major accelerator with HTS
magnets playing a crucial role.