1. High Temperature Superconductivity (HTS) Opportunities & Challenges;
Journée thématique DAPNIA
«Almants supraconducteurs»
High Temperature Superconductivity (HTS)
Opportunities & Challenges;
R&D Activities in the US
Yukikazu IWASA
Francis Bitter Magnet Laboratory
Massachusetts Institute of Technology
Cambridge, MA
Orme des Merisiers, Bât. 774, Amphi Bloch, Saclay
lundi 3 juillet 2006
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

2. Outline Review of LTS & HTS Characteristics
HTS  Current Status (Bi-2223; Bi-2212; YBCO; MgB2)
Key issues
Opportunities
HTS R&D Activities in the US
Challenges
Important Activities for HTS
Market Penetration for HTS
Conclusions
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

3. oHc2 vs.Tc Plots for LTS & HTS
150 50
100
Tc [K]
oHc2 [T]
YBCO
OXIDE
Bi-2212
Bi-2223
Bi2Sr2Can-1CunO2n+4:
(BSCCO)
(n=2)
OXIDES
(n=3)
MgB2
COMPOUND
Nb3Sn
COMPOUND
Nb-Ti
ALLOY
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

4. Jc Data: LTS @4.2 K HTS @4.2 K & Above Useful range for magnet
105
Useful
range for
magnet
YBCO (4.2; 75)
MgB2 (4.2;20)
104
Nb-Ti (1.8; 4.2)
Bi-2212 (4.2)
Bi-2223 (4.2; 20)
103
Jc [A/mm2]
Nb3Al
( 4.2)
Nb3Sn (1.8; 4.2)
102 10 5 10 15 20 25 30
B [T]
[Based on graph by P. Lee (12/2002; UW)]
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

5. Bcenter vs Top Zones for LTS & HTS Magnets 50 40 30 20 10
Top[K]
Bcenter [T]
YBCO
Bi-2223/2212
MgB2
Nb3Sn
Nb-Ti
HTS Opportunities: higher fields over wider Top range
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

6. HTS  Current Status Bi-2223
 Available NOW as “magnet grade conductor”
 Only as TAPE
0.22
4.2 mm
Sumitomo Electric Bi-2223
[T. Kato (Sumitomo) (2006)]
Difficult to reduce AC losses  suitable for DC coils
“Pancake” coils rather than “layered” coils
 many joints
“large” radial gaps needed in multi-coil inserts
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

7. HTS  Current Status (continuation)
Bi-2212
Easier to minimize AC losses
“Layered” coils
 Suitable for multi-coil “inserts”
 Available in WIRE form
0.8 mm
18 sub-element each of
37 filaments
NEXANS Bi-2212 Wire
[Jean-Michel Rey (2006)]
 Still under development
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

8. HTS Current Status (continuation)
YBCO
 Usable at LN2 temperatures (>64 K)
Considered by many that YBCO less expensive than
Bi-2212/2223  low materials costs, e.g., no Ag
 Only as TAPE  same negative points as Bi-2223
Even AFTER MORE THAN 10 years, still the longest
available ~100 m
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

9. HTS  Current Status (continuation)
MgB2
 Available as WIRE  same positive points as Bi-2212
 Considered by many to be price-competitive against Nb-Ti
Jc (>10 K) still much less than Nb-Ti’s K)
More brittle than Nb-Ti
[Mike Tomsic (Hyper Tech) (2006)]
Nb barrier
MgB2 Cu
0.87 mm 36-filament wire
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

10. Key Magnet Issues vs. Top
Difficulty or Cost
Protection
Conductor
Mechanical
Stability
Cryogenics
~100
Top [K]
Range of Operation
for LTS Magnets
Range of Operation
for HTS Magnets
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

11. → higher J Opportunities Stability
HTS magnets VERY stable  immune from disturbances,
e.g., mechanical, that still afflict LTS magnets
→ higher J
ALL HTS magnets should be “adiabatic’’
 Saving in production cost
Unnecessary to epoxy-impregnate HTS windings?
 Saving in production cost
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

12. Opportunities (continuation)
ALL HTS magnets, except those combined with LTS magnets,
should be dry, cryocooled!
 the presence of liquid cryogen
in the system tends to make cryogenics too “visible” to the user
TWO reasons why LHe NOT needed:
1. HTS magnets CAN operate well above LHe temperatures
2. “Large” temperature margins for HTS magnets
[dT/dt  0]LTS not mandatory for HTS magnets
ONE serious disadvantage for dry magnets:
Nearly ZERO thermal mass for the cold body
ENTER: solid-cryogen-cryocooled “dry” HTS magnets
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

13. Cp(T) Plots Phase transition (35.6 K): 8.3 J/cm2 SNe SN2 Pb Ag Cu 2.0
1.5
1.0
0.5 10 20 30 40 50 60
T [K]
Cp [J/cm3 K]
Cp(T) Plots
Llv = 2.56 J/cm3
for LHe
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

14. Opportunities (coontinuation)
When MgB2 can replace Nb-Ti, and Bi-2212/2223 and/or
YBCO can replace Nb3Sn, it should be possible to make
magnets  NMR/MRI; HEP; even FUSION  entirely of
cryocooled HTS operating >10 K, with ZERO possibility of
quenches
“Dry” magnet tends to make cryogenics “invisible”
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

15. Opportunities for LTS & HTS Magnets: Present & Future DC or ~DC
Applications
Current Status
DC or ~DC
LTS: present
HTS: future
LTS (marketplace); HTS (R&D)
Medical MRI
LTS (marketplace); HTS (R&D)
Magnetic Separation
Crystal (Si) grower
LTS (marketplace); HTS (R&D)
LTS (marketplace); HTS (R&D)
NMR/MRI
DC field
RESEARCH MAGNET
LTS (“Teva;” LHC); HTS (R&D)
HEP
LTS (TORE SUPRA; ITER); HTS (R&D)
Fusion
Electric Power  Conversion & Storage
LTS (R&D); HTS (R&D)
HTS bulk disk (R&D)
Generator
SME
Flywheel
DC or ~DC
LTS: proven
HTS: better?
AC or DC
Hope hinges
on HTS
HTS (R&D)
Transmission Transformer
Fault current limiter
Electric Power  Distribution
HTS (R&D)
Motor
Electric Power  End Use
LTS (R&D); HTS (R&D)
MAGLEV
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

16. HTS R&D Activities in the US
Nearly ALL US superconductivity R&D activities on HTS
Major federal government HTS R&D activities targeted to
devices (electric utilities & military) and YBCO
~$40M/Y
1) HTS electric power devices; 2) YBCO
DOE
Budget
Principal Areas
Sponsor
~$10M/Y
YBCO
Air Force
(lightweight magnets; protection)
[a] Total for two motors, 5MW (2003) & 36.5MW (2006)
$80M [a]
Synchronous motors (Bi-2223) for ship propulsion
Navy
[b] National Science Foundation
~$25M/Y
Operates the NHMFL national facilities
NSF [b]
[c] National Institutes of Health
[d] Supports, among others, four HTS NMR/MRI magnet projects currently at MIT
Pays for many LTS NMR & MRI magnets [d]
NIH [c]
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

17. Opportunities (continuation)
Selected 1-GHz NMR Magnet Projects
Based entirely on LTS
1 GHz NRIM (Japan)
1 GHz Oxford Instruments
Based on LTS/HTS
1 GHz: MIT (Bi-2223)
1.2 GHz: Grenoble/Saclay (Bi-2212)
1.3 GHz: NHMFL (Bi-2212)
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

18. 3-Phase MIT 1-GHz LTS/HTS NMR Magnet Project*
Phase 2 ( ): 700 MHz
600 MHz / 100 MHz/ 55 mm RT bore
600 LTS K)
140-mm COLD bore
[JASTEC]
100 HTS K)
40 Double Pancake Coils
55-mm RT bore
Bi-2223-Tape
Double Pancake Coil
126.5
78.2
401.6
* A US HTS activity (supported by NIH)
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

19. 3-Phase MIT 1-GHz LTS/HTS NMR Magnet Project (cont.)
Phase 3 ( )*: 1 GHz
760 MHz / 240 MHz / 63 mm RT bore
175
Nb3Sn
Nb-Ti
760 LTS K)
175-mm COLD bore
[JASTEC (2005)]
Bi-2223
240 HTS K)
63-mm RT bore
64 Double-Pancake Coils 87
* NIH yet to approve Phase 3
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

20. 1.2-GHz LTS/HTS NMR Magnet Project
Grenoble/Saclay
1.2-GHz LTS/HTS NMR Magnet Project
Phase 1: 850 Cu/350 HTS
160
850 (20 T)/20 MW Cu Magnet (Grenoble)
[Jean-Michel Rey (2006)]
3-Coil HTS (Bi-2212) Insert
(Saclay)
136
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

21. March Towards 1 GHz & 1.2 GHz Bo [T] YEAR 50 54 2 4 6 8 10 12 14 16 1820 22 24 26 28
: SUPERCONDUCTING—LTS/HTS [GHz] 1
1.2
March Towards 1 GHz & 1.2 GHz
MIT?
Grenoble/
Saclay?
: SUPERCONDUCTING—LTS [MHz]
200
220
270
360
500
600
750
800
900
930
950
1000
: NON-SUPERCONDUCTING [MHz] 30 40 60
100
MIT
YEAR
[Based on Kobe Steel data (1998)] 58 62 66 70 74 78 82 86 90 94 98 02 06 08 10 12 14
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

22. Challenges Conductor Develop “long” (~10 km) conductors
Reduce AC losses in Bi-2223 & YBCO (tapes)
Reduce price/performance ($/kA m)
For NMR/MRI magnets
Develop superconducting joints
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

23. Current-Carrying Capacity vs. Price/Length Plots
0.1 1 10
100
1,000
10,000
Price [$/m]
103
104
105
I [A] 
Nb3Sn
Tape
(10 K; 1 T)
$10/kA m
Nb-Ti
(4.2K; 6T) 
$1/kA m 
ITER
Nb3Sn
(5.5 K; 13 T)
$100/kA m 
Bi-2223 (2006)
(77.3 K; s.f.)
$200/kA m
YBCO ( )
(77.3 K; s.f.)
MgB2
( )
(20 K; 2 T.)
$2-5/kA m
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

24. Challenges (continuation)
Cryogenics
Easier for HTS than for LTS, but its ratio of compressor power
QRT to refrigeration power at Top, Qop , needs MUCH (QRT /Qop ) 10
100
1000
10000 1
1 W
10 W
100 W
1 kW
100 kW 20 30 40 50 60 70 80
Top [K]
QRT /Qop
QRT /Qop vs. Top for Selected Qop
CARNOT
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

25. Comparison of HTS vs. Cu Devices
For an HTS device to compete its Cu counterpart operating at room temperature (RT), its dissipation at Top, PHTS [W/m], multiplied by the refrigerator’s compressor-to-cooling power ratio, QRT /Qop, < Cu’s Joule dissipation, PCu [W/m]
PHTS  (QRT /Qop) < PCu
PCu /PHTS > QRT /Qop
10 kW
100 W
1 kW
400
180 75 45 20 10
850
380
140 70 30 15
1500
500
220
110 50 22
8000
1650
600
350
120 55
4.2 77
Top [K]
1 W
Qop
QRT /Qop
Challenge: Cryogenics
QRT /Qop  , i.e., refrigerator
efficiency
Challenge: AC Losses
PHTS  to satisfy PCu /PHTS > QRT /Qop
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

26. Comparison of Two Systems: An Illustrative Example
HTS (YBCO) & Cu Transmission “Lines”  Based on HTS
Refrigeration Power Requirement, Qop  PHTS vs. PCu = I2R
HTS w s
s
YBCO
Substrate;
stabilizer,
etc. w
s Cu
Dimensions & Characteristics
of “Basic (Ic =100 A) HTS tape
w = 4x103 m (4 mm)
s = 1x106 m (1 µm)
 = 100
Ic = 100 A (77.3 K, s.f.)
Jc = Ic / (ws)= 2.5x1010 A/m2
s = 1x104 m (100 µm)
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

27. Two-System Comparison (continuation)
Self-Field AC Loss Power/length, PHTS [W/m], of HTS Line
composed of n 100-A “basic” tapes operated at IT = n  (It /Ic)
PHTS
Pcu
Power Density/length, Pcu [W/m], in Cu Tape w
s Cu
Figure-Of-Merit (FOM):
Pcu
PHTS
QRT
Qop
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

28. Pcu /PHTS & FOM vs. i for 10-kA (nominal) Lines @77 K
10000
1000
100 10 1
0.2
0.4
0.6
0.8 i
Pcu / PHTS
Pcu /PHTS & FOM vs. i for 10-kA (nominal) K
33 W/km (PCu/PHTS=6460)
100 K (QRT / Qop =22)
FOM=294
540 W/km (1600)
1 K (QRT / Qop =15); 107
2.8 kW/km (700)
10 K (10); 70
9.1 kW/km (380)
10 K (10); 38
HTS non-competitive to Cu
77-K operation possible, but, at least in
this example, a 10-kA HTS line superior
to the Cu line only when the HTS line operated at currents below 5 kA
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

29. Two-System Comparison (continuation)
Pcu
PHTS
QRT
Qop =
Ways to improve FOM:
Improved YBCO K )
Thinner substrate ( )
Improved refrigerator (QRT / Qop)
Challenges: YBCO
Challenge: Cryogenics
LTS’s Failure in Power Applications:
QRT 4.2 K too large to satisfy PCu /PLTS > [QRT /Qop]4.2 K
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

30. Protection
“Expensive” magnets must be protected from permanent damages
LTS magnets generally rely on NZP
(normal zone propagation) to spread out
the resistive zone to keep the “hot spot”
temperature well below 300 K
NZP
Quench
Initiation
Zone
(“Hot spot”)
In HTS magnets, NZP velocities (longitudinal
& transverse), compared with those in LTS
magnets, very slow, leading to a dangerously
high “hot spot” temperature
for HTS Ccd (T) very large UHTS << ULTS
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

31. Challenges (continuation)
Protection
Develop fail-safe protection techniques
Develop normal-zone detection techniques
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

32. Important Activities for HTS
BUILD and operate MAGNETS: LTS, LTS/HTS, HTS
Enhance test facilities for evaluation of HTS
Ic measurement (up to: 500 A; 30 T; 100 K; 0.5%)
R&D Areas, besides conductor
Protection
Cryogenics
QRT /Qop or efficiency even at 77 K
Make cryogenics LESS visible to the user 
solid-cryogen may help achieve this goal
Superconducting joints (for NMR/MRI)
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

33. Market Penetration for HTS
HTS applications most likely to succeed and benefit
society, i.e., market penetration, include:
DC or nearly DC devices: those already conquered by LTS,
e.g., NMR/MRI; HEP; even fusion
If HTS replacing technology to LTS  its marketplace
penetration to be decided by ECONOMICS
Conductor cost/performance ($/ka m); AC losses;
Cryogenic efficiency
If HTS enabling technology, e.g., high-field NMR and MRI,
its success dictated by HTS PERFORMANCE
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)

34. Merci beaucoup Conclusions HTS for NMR/MRI: work already started
HTS for HEP & fusion: NOT TOO EARLY to begin planning
For the most prized application  in terms of sheer volume 
electric power, LTS NOT ENABLING: hope hinges on HTS
HTS  opportunities & challenges  will keep ALL of us
innovative, relevant, and productive for a long time !
Merci beaucoup
Y. IWASA (FBML)
DAPNIA Day  HTS
Saclay (03/07/2006)