Status of and prospects for advanced tokamak regimes from multi-machine comparisons using the...

JET Seminar 15 December 2003 and 9th IAEA Technical meeting on H-mode Physics & Transport Barriers, 24-26 Sept. 2003 by X. Litaudon et al 1

Status of and prospects forAdvanced Tokamak regimes

from multi-machine comparisons using the‘International Tokamak Physics Activity’ database

By Xavier LITAUDON

In collaboration withE. Barbato, A. Bécoulet, E.J. Doyle, T. Fujita, P. Gohil, F. Imbeaux, G. Sips

for the ITPA Group on Transport and ITB Physicsand for the

International ITB Database Working Group and the RO for the ITPAcollaborative experiments on the ‘hybrid’ and ‘steady-state’ regimes

Euratom


Author listX. Litaudon1, E. Barbato2, A. Bécoulet1, E.J. Doyle3, T. Fujita4, P. Gohil5, F. Imbeaux1, G. Sips6,for the International Tokamak Physics Activity (ITPA) Group on Transport and Internal Transport Barrier (ITB) Physics: J. W.Connor7, E.J. Doyle3,Yu. Esipchuk8, T. Fujita4, T. Fukuda9, P. Gohil5, J. Kinsey10, N. Kirneva8, S. Lebedev11, X. Litaudon1, V. Mukhovatov12, J. Rice13, E. Synakowski14, K.Toi15, B. Unterberg16, V. Vershkov8, M. Wakatani17* and for the International ITB Database Working Group and the responsible officers for the ITPAcollaborative experiments on the ‘hybrid’ and ‘steady-state’ regimes : T. Aniel1, Yu.F. Baranov7, E. Barbato2, A. Bécoulet1, C. Bourdelle1, G.Bracco2, R.V. Budny14, P. Buratti2, E.J. Doyle3, Yu. Esipchuk8, B. Esposito2, S. Ide4, A.R. Field7, T. Fujita4, T. Fukuda4, P. Gohil5, C. Gormezano2,C. Greenfield5, M. Greenwald13, T.S. Hahm14, G.T. Hoang1, J. Hobirk6, D. Hogeweij18, S. Ide4, A. Isayama4, F. Imbeaux1, E. Joffrin1, Y. Kamada4, J.Kinsey9, N. Kirneva8, X. Litaudon1, T.C. Luce5, M. Murakami19, V. Parail7, Y-K M. Peng19, F. Ryter6, Y. Sakamoto4, H. Shirai4, G. Sips6, T. Suzuki4,E. Synakowski14, H. Takenaga4, T. Takizuka4, T. Tala20, M.R. Wade19 and J. Weiland21

1 Association EURATOM-CEA, 13108 St Paul lez Durance, France2 Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati, Italy3 University of California, Los Angeles, CA 90095, USA4 JAERI, Naka Fusion Research Establishment, Naka, Japan5 General Atomics, P.O. Box 85608, San Diego, California, 92186-5608 USA6 Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germany7 UKAEA-EURATOM Association, Culham Science Centre, Abingdon, OX14 3DB, UK8 Kurchatov Institute of Atomic Energy, Moscow, Russia9 Osaka University, Suita, Japan10 Lehigh University, Bethlehem, PA 18015, USA11 Ioffe Institute, St Petersburg, Russia12 ITER JWS, Naka, Japan13 Massachusetts Institute of Technology, Cambridge, MA 02139, USA14 Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543, USA15 National Institute of Fusion Science, Toki City, Japan16 Institut für Plasmaphysik, Forschungszentrum Jülich GmbH Association EURATOM-FZJ, Jülich, Germany.17 Kyoto University, Kyoto, Japan18 FOM Insituut voor Plasmafisica, ‘Rijnhuizen’, Nieuwegein, The Netherlands19 Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA20 VTT Processes, Association Euratom-Tekes, P.O. Box 1608, FIN-02044 Finland21 Chalmers University and EURATOM-VR association, Gothenburg, Sweden* Deceased


International Tokamak Physics Activity (ITPA)

• The ITPA is a collaboration involving the European Union, Japan,Russia, United States and China� Activity formally commenced in September 2001� Replaced the ITER Expert Group Activity

• The primary role of the ITPA is the coordination of VoluntaryPhysics R&D within the the Participant’s Fusion Programs

• ITPA structures essentially continue the ITER Physics EGactivities, but with broader scope relating to Burning PlasmaPhysics� Organized into seven Topical Groups, including Transport andITB Physics TG (Chairman E.J. Doyle)� ‘Transport and ITB physics’ group has been renamed ‘Transportphysics’ in Sept. 2003


Research priorities for the Transport Physics group• Develop worldwide multi-machine international database of

advanced tokamak regimes : global and profile data• Test of physics of ITB formation & sustainement• Test of transport simulations (empirical and theory based models)• Pursue understanding of critical issues for reactor relevant

advanced tokamak regimes• Provide predictive capability of AT regimes for burning plasmas• Demonstrate burning plasma compatible operating regimes based

on improved core transport properties• Propose international collaborative experiments

Fukuda T et al 2001 in proc. 28th Eur. EPS Conf. (Funchal, 2001)

Sips A C C et al 2002a Plasma Phys. Control. Fusion 44 A391

Hoang G T et al 2002 Proc. 29th EPS Conf. (Montreux, 2002) Vol. 26B P-4.068

Gohil P et al 2003 Nucl. Fusion 43 708

Fujita T et al 2003 in proc. 30th EPS, 7-11 July 2003, St Petersburg (EPS)

Connor et al 2003 to be published in Nuc. Fusion

Recent publications


Motivation for this work

• To date, the international ITB database has been mainly used tostudy the ITB formation conditions (prelude phase)

• In this paper, assessment of the present fusion performance of theadvanced tokamak regimes for non-inductive operation (highperformance phase of the scenario)

• Map the operational domain of AT regimes in terms of performancebut also in term of dimensionless plasma physics quantities such asnormalised Larmor radius��collisionality,��Mach Number and ratio ofion to electron temperature

• Quantify the gap between present day and future advanced tokamakexperiments

• Identify the required experimental effort to reduce the uncertaintieswhen extrapolating non-inductive regimes to next step experiments


ITER non-inductive scenarios• ITER scenarios :

� inductive (high current ELMy H-mode)� ‘hybrid’ scenario� Fully non-inductive current drive operation

• ‘Hybrid’ scenario�Long pulse operation� Q ~ 5-10 �q95 ~3-4 � monotonic q-profile q0 ~ 1-1.5 � HH ~ 1 �N ~ 2 � Ibs/Ip ~ 20%

References : Green B J et al 2003 Plasma Phys. Control. Fusion 45 687ITPA Group on Steady-state Operation and Energetic Particles

• ‘Steady-State’ scenario�fully non-inductive operation�Q ~ 5�q95 ~4-5�Non-monotonic q-profileqmin ~ 2 �0.5 q0 – qmin <0.5� HH ~ 1.5-2 �N ~ 3� Ibs/Ip > 50%

• Attractive Steady-State reactor operation Ibs/Ip > 80% �N > 4


Typical q-profiles for advanced scenariosexample from JET

Major radius [m] Major radius [m]

q(R) q(R)

"Hybrid" scenario "Steady-State" scenario

#58179t ~ 4.2s

#57971t ~ 4.6s

1< qmin < 1.5qmin 2

shear reversal


Data selected for this paper (1/2)

• New entries have been added to the international database thatconsist of data taken during the well developed high performancephase of the discharges

• Data from both the ‘hybrid’ (without necessarily an ITB) or the‘steady-state’ scenarios. These scenarios are the two candidatesfor the ITER non-inductive current drive operation [1-2] .

• Advanced regimes from ASDEX Upgrade, DIII-D, FT-U, JET, JT-60Uand TORE SUPRA

[1] Campbell D.J. et al 2001 Phys. of Plasmas 8 2041[2] Green B J et al 2003 Plasma Phys. Control. Fusion 45 687


743 AT discharges selected for this paper (2/2)

ASDEX Upgrade 372 Ion/electron ITB (94)‘Hybrid’ scenario (218)

Wolf et al 1999Sips et al 2002b

FT-U 3 Electron ITB (3) V. Pericoli et al 2003

DIII-D 9 ITB with weak and reversedmagnetic shear (4)‘Quiescent Double Barrier’ (2)Steady-state scenario (2)‘Hybrid’ scenario (1)

Strait E J et al 1995Wade et al 2003Doyle et al 2001Luce et al 2003

JET UndertakingEFDA-JET

25277

ITB regime with weak and reversedmagnetic shear‘Hybrid’ scenario (27)

JET team 1999 Gormezanoet al 1999Challis et al 2001&2002Litaudon et al 2003Joffrin et al 2001Sips et al 2003

JT-60U 17 High �p regime (9)Negative magnetic shear (8)

Kamada et al 2001Ide et al 2002Fujita et al 2001Fujita et al 2002

Tokamak Entries Advanced regime References

TORE SUPRA 40 Full current drive operation (22)Electron ITB (4)High �p (Fast Wave electron heating)(13)Pellet Enhanced mode (1)

Jacquinot et al 2002Litaudon et al 2001Equipe TS 1996Saoutic et al 1994Géraud et al 1994


Operational diagram for AT operation : Figure of merit of fusion performances vs �p

• The filled symbols �D�� > 10, where �D/�E the duration of the highperformance phase, �D , normalised to the energy confinement time, �E

• �D is defined as the duration where Wdia� 85%max(Wdia)

� Bootstrap current fraction

� F

usio

n pe

rform

ance

• Three domains ofoperationdepending onperfomance &steady-statecapability

0.8

0.6

0.4

0.2

0

HIT

ER-8

9Px�

N/q

2 95

1.61.20.80.40�

��

�p

2.8�q95<3.43.4�q95<44�q95<55�q95<6q95�6

ITER Q~5non-inductive

ITER Q~10inductive


Operational diagram for AT operation : Figure of merit of fusion performances vs bootstrap fraction

0.8

0.6

0.4

0.2

0

HIT

ER-8

9Px�

N/q

2 95

1.00.80.60.40.20Iboot./Ip

2.8�q95<3.43.4�q95<44�q95<55�q95<6q95�6

ITER Q~5non-inductive

ITER Q~10inductive

• 89 discharges• Bootstrap currentfrom neo-classicalcodes using 1-Dprofiles [ACCOME,ASTRA, CRONOS,TRANSP]


Relevance of this operational diagram

• Assess the progress both in terms of Fusion Performances andprospect for steady-state through the optimisation of the bootstrapcurrent fraction

• Machine size independent that allows a multi-machine and multi-regime comparison:

� H�N/q295 is machine size independent parameter that quantifies both the

fusion power density � ��

N/q295 �and triple fusion product � H2/q2

95

� Bootstrap current fraction is either calculated or � �� p : The machine

dependence is included within �

• In this diagram, there is a continuous progression from the‘inductive’ to the ‘hybrid’ and ‘steady-state’ tokamak operatingmode


Triple fusion performance versus duration

Maintaining performances for a long duration requires operatingrelatively

far from the maximum operational limit

0.01

0.1

1

10

100n io

T io�� [1

019m

-3 k

eV s

]

10-1 100 101 102 103 104

�D/�E

ITER Q=5 ASDEX-U DIIID FT-U JET JT-60U Tore Supra


Operational limit: towards high density

80.01

2 4 6 80.1

2 4 6 81

2

��

ITER Q~5

1.00.80.60.40.20nel�nG

ITER Q~5

4

3

2

1

HITER-89P

1086420nel [1019 m-3]

ITER Q~5

0��<0.10.1��<0.20.2��<0.30.3��<0.4��0.4

• difficulties to reach high density + confinement : is it an edge or core limit ?• high � is favourable• at nel/nG~0.8-1 increasing H > 2 require a wide ITB ?• but reduced density allows operation close to ITER collisionality


Operational limit : towards high �N

• High �N requires broad pressure peaking, i.e. a wide zone ofimproved core confinement: � in ITB plasmas, a wide ITBs should be formed and sustained.

4

3

2

1

0

�N

121086420Pressure peaking factor

�D / ��10

�D / ��10 •x ‘hybrid regime’ with

qo~1-1.5 and q95 � 4

• pressure peaking isdefined as neoTeo/nel‹Te ›


Operational domain in term of normalised quantities

• �e* the effectivecollision frequency forthe trapped particlesnormalised to theirbounce frequency,�e*�neqR/(�3/2Te

2)

• �*=�s/a the normalisedion Larmor radius at thesound speed where�s=cs/�ci�Te

1/2mi1/2/(ZaB

�)

JET : domain of reduced �e* and �* (�e*<0.05 and �*<3x10-3)� high field, Bo�3.5T, high te~3keV, moderate density,ne~2x1019m-3 at q95~4-5 (Ip~3MA)

0.01

2

468

0.1

2

468

1

2

�*

0.0012 3 4 5 6 7 8 9

0.01��

ASDEX -U DIIID FT-U JET JT-60UTore Supra

ITERQ~5

Filled symbols H�N >4


�N and fusion figure of merit versus �* for various �*

• High HITER-89P�N/q295 obtained close to ITER �e*

• Low values of �* expected in ITER have been obtained butat low performances (�N< 1.5 and HITER-89P�N/q2

95<0.2) and highcollisionality (�e*~0.1)

4

3

2

1

0

�N

0.0012 3 4 5 6 7 8

0.012

��

��<0.030.03��<0.1��0.1ITERQ~5

0.8

0.6

0.4

0.2

0

H ITE

R-8

9Px�

N/q

2 95

0.0012 3 4 5 6 7 8

0.012

��

��<0.030.03��<0.1��0.1

ITERQ~5


Confinement enhancement versus Tio/Teo

at various Mach numbers

• Higher confinement factor should be obtained at Ti/Te ~1

4

3

2

1

0

HIT

ER-8

9P

43210Tio/Teo

M�<0.4

0.4�M�<1.2

M��1.2

ITERQ=5

• M�

~ v�o/cs


�N and fusion figure of merit versus Tio/Teoat various Mach numbers

• M��

=V��

/cs where V� is the core toroidal rotation and cs is the ion sound speed

• Data at Tio/Teo~1 and HITER-89P�N/q295~0.3-0.4 have been obtained in the ‘hybrid’

regime : ASDEX, JET and JT-60U (‘high �p’)• High performances at low M

��(�N >2, HITER-89P�N/q2

95>0.4 and M��): ASDEX-U

(hybrid regime) and JT-60U with a combination of co and counter current NBI

4

3

2

1

0

�N

43210Tio/Teo

M�<0.4

0.4�M�<1.2

M��1.2

ITERQ~5

0.8

0.6

0.4

0.2

0

HIT

ER-8

9PX�

N/q2 95

43210Tio/Teo

M�<0.4

0.4�M�<1.2

M��1.2ITER

Q~5


Discussion and conclusion (1/3)

• Extensive database on Advanced Tokamak operation (743 discharges)

• A new operational diagram characterising advanced tokamakoperation using multi-machine database : the figure of merit for fusionperformance and confinement HITER-89P�N/q2

95, versus the bootstrapcurrent fraction

• In this diagram, there is a continuous progression from the ‘inductive’to the ‘hybrid’ and ‘steady-state’ tokamak operating mode

• Significant progress: HITER-89P�N/q295~0.3-0.4 at �p ~ 1, Iboot/Ip~50% and

q95 ~ 5. This range of performances is expected for Q=5 non-inductivecurrent drive operation for ITER.

• High performance regime with Iboot/Ip >70% is still unexplored.


• fusion performances tend to decrease with the pulse duration :extending the plasma performances achieved on a short timescale requires operating safely far from the operational limits

• difficulties to reach high density + confinement : at �ne�/nG~0.8-1H � 2

� is it an edge or core limits ?� at �ne�/nG~0.8-1 increasing H > 2 might require a wide ITB ?� High ��seems favourable for increasing the density

• but reduced density allows operation close to ITER collisionality

• High �N ~ 3 requires broad pressure profiles� wide region with improved core confinement



• ITER plasmas : different domain of dimensionless parameters, low values of��e�� M��

and with Ti/Te~1

• These parameters have been widely scanned in present day AT experiments

• Advanced regimes allow to operate close to ITER �e��. At ITER �e� (�e��,HITER-89P�N/q2

95 ~0.3-0.4 at �� x��i.e.�2 or 3 times above ��for ITER Q=5non-inductive regime.

� cross-machine experiments : assess the variation of ��e��TI/Te …�on AT

performances��

• JET and JT-60U could be considered as ‘test bed’ for AT regimes beforeextrapolating their performances to future larger tokamaks

• experimental effort should be devoted to developing high fusion yieldregimes with a larger fraction of electron heating to operate at Ti/Te closer tounity while simultaneously keeping low values of ��and �e�



Figure of merit versus durationof the high performance phase

��D/�E the duration of the high performance phase, �D , normalised tothe energy confinement time, �E

• The challenge is toextend the duration of thefusion performance:� technical and scientificissues

0.0012

46

0.012

46

0.12

46

1

HIT

ER-8

9px�

N/q

2 95

10-1 100 101 102 103 104

�D/�E

ASDEX FT-U DIIID JETJT-60U TS

ITER Q=5


Confinement enhancement versus �* and Tio/Teo

• Higher confinement factor should be obtained at Ti/Te ~1

4

3

2

1

HIT

ER-8

9P

0.0012 3 4 5 6 7 8

0.012

��

��<0.030.03��<0.1��0.1ITER

Q=5

4

3

2

1

0H

ITER

-89P

43210Tio/Teo

M�<0.4

0.4�M�<1.2

M��1.2

ITERQ=5

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