IN TORE SUPRA

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15 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

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1

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

PIONEERING SUPERCONDUCTING MAGNETS IN
LARGE TOKAMAKS : EVALUATION AFTER 16
YEARS OF OPERATING EXPERIENCE

IN TORE SUPRA


P. Libeyre
,

J.
-
L. Duchateau,
B. Gravil,

D. Henry, J.Y. Journeaux, M. Tena, D. van Houtte


Association EURATOM
-
CEA, CEA/DSM/DRFC

CEA Cadarache (France)


2

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004


The Tore Supra tokamak at CEA Cadarache

3

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

1.
Introduction


2.

Status

of

the

Tore

Supra

Toroidal

Field

(TF)

system


3.
Normal

operation


4.
Fast

safety

discharges


5.
The

cryogenic

system


6.
Can

the

magnet

experience

of

Tore

Supra

be

useful

for

ITER

?


7.
Conclusion

4

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

1.

Introduction (1/4)

The Tore Supra TF magnet during assembly

5

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

1.

Introduction (2/4)


Tore Supra TF coil structure

Supercritical helium
(4.5 K) in thick casing
channels

Superfluid helium
(1.8 K) in thin casing

bare conductors

in superfluid helium !


6

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

1.

Introduction (3/4)



one of the largest

superconducting system in operation


(600 MJ magnetic energy)



Relying

on

a

refrigerator

including

for

the

first

time



industrial

quantities

of

superfluid

helium

(

Claudet

bath)

The Tore Supra TF system is :


O
perated daily close to nominal conditions (1250 A)


since November 1989.

Continuous toroidal field on the whole day

7

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

1.

Introduction (4/4)


The path to
steady
-
state
operation


Introduction of a new type of refrigeration for
superconducting magnets on an industrial level :



Thousands of litres in TS (1988)



Hundreds of thousands litres in LHC (2007) !





the continuous toroidal field allows long duration
plasma experiments to be performed


The revolution
of

superfluid
helium

The Tore Supra TF system contribution

J.L Duchateau et al.
“Monitoring and controlling Tore Supra toroidal field system: status


after a year of operating experience at nominal current“
1991 IEEE Trans.
On Magn. 27 2053


8

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

2
.

Status of the Tore Supra TF system (1/3)


1982
-
1988

coil manufacture and magnet assembly





all coils

tested up to
nominal current

(1 400 A) at Saclay

1988

start of operation





short circuit

in BT17 during a fast safety discharge

1989

replacement of BT17 by spare coil BT19




acceptance tests of TF coils up to 1450 A (9.3 T)





quench

of BT13 during fast safety discharge (FSD)






limitation of operating current to
1250 A






temperature increase observed in BT13 during FSD

1995

disparition of defect on BT13





no more temperature increase in BT13 during FSD


2002

continuous data acquisition system

9

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

2
.

Status of the Tore Supra TF system (2/3)


Similar behaviour of

BT13 compared to
the other coils

1.65
1.70
1.75
1.80
1.85
1.90
1.95
2.00
2.05
2.10
2.15
-500
1500
3500
5500
7500
9500
Time (s)
Coil temperature (K)
4.4
4.6
4.8
5
5.2
5.4
5.6
5.8
6
6.2
6.4
Thick casing helium temperature (K)
BT13
Temperature
BT16, BT17
Temperatures
Thick casing
coil helium
temperature
Green light


for TF operation

1.87 K


No more apparent defect on BT13

Temperature increase in coils during FSD (2003)

10

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

1000
1100
1200
1300
1400
1500
1600
1700
1800
6
7
8
9
10
11
12
13
Magnetic Field [T]
Current [A]
Coil Critical
current at 1.8 K
(except BT19)

Operation point

Critical point


Large margin
(2.4 K)

reduced

nominal

Load line

Coil Critical
current at 4.2 K
(except BT19)

Safe operation of the TF magnet since 1989 at 1250 A, 8 T

2
.

Status of the Tore Supra TF system (3/3)

BT19

BT19

11

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

3.

Normal operation (1/4)

Tore Supra

TF activity

Since 1988

0
100
200
300
400
500
600
700
800
120/600
600/900
900/1200
>1200
Range of TF current (A)
Number of TF cycles
Since 1988 :





13

thermal cycles from room to LHe temperature





1 090

TF cycles




20 074

plasma discharges

12

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

3.

Normal operation (2/4)


Winding
-
pack temperature during one day of operation

0
0.2
0.4
0.6
0.8
1
1.2
5
7
9
11
13
15
17
19
21
23
Time ( h )
Plasma current (MA) and
TF current (kA)
1.60
1.62
1.64
1.66
1.68
1.70
1.72
1.74
1.76
1.78
1.80
BT15 coil temperature (K)
TF system current
BT15
Temperature

Plasma
discharges
Long Plasma
discharges
Cleaning Plasma
discharges
Temperature increase at current ramping
-
up and down (0.06 K)

Green light


for TF operation

1.87 K


13

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

3.

Normal operation (3/4)


0
0.2
0.4
0.6
0.8
1
1.2
5
7
9
11
13
15
17
19
21
23
Time ( h )
Plasma current (MA) and TF
current(kA)
4.40
4.50
4.60
4.70
4.80
4.90
5.00
Thick casing helium temperature (K)
TF system current
Thick casing
helium
temperature

Plasma
discharges
Long Plasma
discharges
Cleaning Plasma
discharges
Thick casing helium temperature during one day of operation

Temperature increase linked to cleaning plasma discharges

14

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

3.

Normal operation (4/4)


Temperature increase due to a disruption from 1.7 MA


2.69

2.70

2.71

2.72

2.73

2.74 s

-
400

-
200

0

200

400

600

800

1000

1200

1400

1600

TS#31828

dI
P
/dt (MA/s)

I
P
(kA)

Plasma disruption


Thick casing : + 0.83 K

4.5
4.6
4.7
4.8
4.9
5
5.1
5.2
5.3
5.4
5.5
-50
50
150
250
350
450
time (s)
Thick casing helium temperature (K)
1.695
1.7
1.705
1.71
1.715
1.72
1.725
Coil temperature (K)
Coil temperature
Thick casing
helium temperature
Winding
-
pack : + 0.02 K

18/09/03

15

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

4.

Fast Safety Discharges (1/3)


FSD


Largest voltage
at terminals
(320 V at 1400 A)

Risk of short circuit

(bare conductors)

To be
avoided !


thermal load on
cryogenic system

2h30 to recover

0
2
4
6
8
10
12
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2001
2002
2003
Number of Fast safety discharges
Since 1989 : 75 Fast Safety Discharges of the TF magnet


(on 1090 TF cycles)

0
20
40
60
80
100
120
140
160
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2001
2002
2003
Number of TF current cycles
FSD

TF cycles

16

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

4.

Fast Safety Discharges (2/3)


0
2
4
6
8
10
12
14
16
electric interference
cryogenic system
detection system
power supply
control software
quench
Origin of Fast Safety Discharges since 1994

No FSD due to a
quench !

17

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

4.

Fast Safety Discharges (3/3)


Remedies to Fast Safety Discharges




Increase of trigger delays on alarms as much as possible

without affecting the protection of the coil

in case of a real quench




Sensor conditioning to decrease sensitivity to electric

interference

Optimisation of the protection

18

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

5.

The cryogenic system (1/2)


Availability

sources of unavailability
0
20
40
60
80
100
2002
2003
% of time
control
magnet safety
system
HeII cold
compressor
Manpower : 12 persons

Electric power : 1.1 MW

Cost : 0.5 M

/year

(excluding staff and energy)

92
97
0
10
20
30
40
50
60
70
80
90
100
2003

:

97

%

2002

:

92
%

availability

19

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

5.

The cryogenic system (2/2)


The major tendencies of the cryoplant ageing




loss of electrical insulation of many temperature

sensors located in the depth of the cryostats.



drift of adjustment of the electronic components

dedicated to the magnetic bearings of the cold

compressors.

Preventive
maintenance of
compressor units

Good availability
of the refrigerator

Nevertheless, ageing signs are visible :

20

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

TF system

Tore Supra

ITER

Magnetic energy

0.6 GJ

40 GJ

Superconductor

NbTi

Nb
3
Sn

Conductor type

monolithic bare
conductor



2.8 mm x 5.6 mm

Cable
-
in
-
conduit




TFMC (40.7 mm
Ø)

Conductor current

1.4 kA

68 kA

Discharge voltage

0.5 kV

10 kV

Cooling system

Superfluid helium
bath

Supercritical helium
forced flow

Cryogenic power

1.1 MW

~ 35 MW

6.

Can the TF magnet experience of Tore Supra


be useful for ITER ? (1/4)


21

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

0
10
20
30
40
50
60
70
80
90
100
6
7
8
9
10
11
12
13
14
15
16
Magnetic Field (T)
Critical cable current density
(A/mm2)
NbTi,
1.8 K

NbTi,
4.5 K

Nb
3
Sn,TFMC

-
0.65%, 4.5 K

Tore Supra

ITER

6.

Can the TF magnet experience of Tore Supra

be useful for ITER ? (2/4)


Operation of ITER TF at 11.8 T doesn’t allow NbTi to be used

22

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

6.

Can the TF magnet experience of Tore Supra

be useful for ITER ? (3/4)



Extrapolation of the operation of the TF magnet


from Tore Supra to ITER is not straightforward

Forced flow cooling

Very high voltage
monitoring

Fast safety discharge

Tore Supra : no quench

ITER : quench of all coils

23

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

6.

Can the TF magnet experience of Tore Supra

be useful for ITER ? (4/4)


experience of the CEA
magnet team in conductor
and coil design


16 years of reliable plasma
operation with a TF
superconducting magnet

Decision to build ITER
is possible

ITER magnet R&D
programme

Still to be done

Experience in TS can help :

Design of protection and
monitoring system

Impact on cryoplant

Detailed magnet
operation

Impact on scenarios

24

Association

Euratom
-
CEA

P. Libeyre


Pioneering superconductivity 23rd SOFT, Venice 21 September 2004

7.

Conclusion

The

Tore

Supra

tokamak

is

the

first

important

meeting

between

Superconductivity

and

Plasma

Physics
.


Superconducting magnets can be operated
successfully with plasma physics on the long term



Continuous operation of the toroidal field simplifies

plasma discharge preparation



No significant heat load is associated to long shots



Continuous operation limits fatigue degradation

The Tore Supra TF magnet is a useful tool to
prepare ITER construction and operation