Centre de Recherches en Physique des PlasmasEPFL, Association Euratom-Fédération Suisse, Lausanne,
Switzerland
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010
Progress and scientific resultsin the TCV tokamak
for the TCV team*S. Coda
*including collaborating institutions:IPP, Czech Republic ENEA-CNR Padova,
ItalyEHU, Spain
CEA, France ENEA-CNR Milan, Italy
CCFE Culham, UK
IPP Garching, Germany
ITER-JCT U. Warwick, UK
IPP Greifswald, Germany
NIFS, Japan LLNL, US
F-Z Jülich, Germany IST, Portugal PSFC MIT, US
KFKI, Hungary RRC Kurchatov, RF General Atomics, US
IPR, India Keldysh Institute, RF
CompX, US
ENEA Frascati, Italy CIEMAT, Spain
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
2
• TCV parameters and capabilities• Scientific mission and guidelines• Technical progress• Scientific highlights
Torque-free generation and transport of rotation
Particle and energy transport, turbulence Advanced real-time control Alternative confinement topologies
• Summary and outlook
Outline
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
3
TCV
R = 0.88 m, a = 0.25 m
Ip < 1 MA, BT < 1.54 T
k < 2.8, -0.6 < d < 0.9
4.5 MW ECRH power, 7 steerable launchers
×4
×2
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
4
• Experiments in preparation for ITER• Alternative configurations,
tokamak concept improvement
Scientific guidelines of the TCV program
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
5
ITER preparation + alternative pathsMultiple steerable EC launchers, r/t control
NTM stabilization
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
6
ITER preparation + alternative pathsFlexible shaping
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Highlights of technical progress
• Improved charge exchange spectroscopy
resolution
(from 2 to 1 cm) + sensitivity (5-10×): Ti, vf,
v q , nC
• New digital real-time network to control coils
and EC systems
potential to use massively multichannel
diagnostics
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
8
• TCV parameters and capabilities• Scientific mission and guidelines• Technical progress• Scientific highlights
Torque-free generation and transport of rotation
Particle and energy transport, turbulence Advanced real-time control Alternative confinement topologies
• Summary and outlook
Outline
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
9
Symmetry breaking toroidal momentum transport by turbulenceNew theory validated by TCV experiments
• Static, up-down symmetric plasma: fundamental symmetry upon reversal of v// and poloidal angle net turbulence-driven momentum flux is zero
• Symmetry breaking net momentum flux: from vf, vf, or up-down asymmetry(Y. Camenen et al, PRL 2009)
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Same Bf, Ip
inward
outward
Turbulent momentum transport
Y. Camenen et al, PRL 105, 135003 (2010)
• Radial turbulent momentum flux changes signas expected from up-down flip
• vf varies most at edge where asymmetry is greatest
Bdrif
t
Bq
• Direction of radial fluxshould reverse withBf sign, Ip sign, up-down flip
• All reversals have been confirmed by experiment
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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• observed systematically in TCV L-modes
(no torque)
• at low to moderate current (qedge >3),
vf is counter-current in core
• central rotation is limited by sawtooth
crashes imparting a co-current spin
• vf changes sign at high current and
density
Spontaneous plasma rotation
A. Fasoli, IAEA 2008 overview
New experiments performed to
quantify and document effect of sawteeth
(i.e., 1/1 internal kink) and other MHD modes
study effect of ECRH on rotation
A. Bortolon et al, PRL 2006B.P. Duval et al, PPCF 2007B.P. Duval et al, PoP 2008
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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• Reproducible co-current spin-up inside the inversion radius
• Rapid relaxation (in <15% of sawtooth period)
• Enhanced CXRS time resolution by coherent averaging over multiple sawteeth
Plasma spin-up at sawtooth crash
B.P. Duval et al, EXC/P4-01 (this afternoon)
Inv. radius
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Slightly hollow inside the mixing radius......to the point of changing sign at high enough current
Average effect of sawteeth on rotationSelf-similar gradients outside the mixing radius
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Influencing rotation with ECRHthrough sawteeth
• EC power inside mixing radius hollows out vf profile
• Similar to Ip increase: consistent with effectof current profile peaking on sawteeth
O. Sauter et al,EXS/P2-17
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
15
• TCV parameters and capabilities• Scientific mission and guidelines• Technical progress• Scientific highlights
Torque-free generation and transport of rotation
Particle and energy transport, turbulence Advanced real-time control Alternative confinement topologies
• Summary and outlook
Outline
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Stronger flattening by sawteeth for impuritiesStronger peaking for impurities than for electronsSawteeth affect particle transportsimilarly to momentum transport
Electrons Carbon ions
Similar edge gradients
Y. Martin et al, EXC/P8-13 (Friday afternoon)
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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The effect of shape on turbulence
• Triangularity strongly influences transport: confinement of EC-heated d=-0.4 plasmas is up to twice as good as for d=+0.4 (for similar profiles)
• Gyrokinetic simulations explain this through the effect of toroidal precessional drift of trapped electrons on TEM turbulence
A. Fasoli, IAEA 2008 overview
Y. Camenen et al, NF 2007A. Marinoni et al, PPCF 2009
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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The effect of shape on turbulence• Measurements of temperature fluctuations by
a tunable 2-channel correlation ECE system reveal a broadband spectrum in the expected 20-150 kHz range
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Longer correlation length at d>0larger random-walk step, consistent with more
transport
B. Labit et al, EXC/P8-08 (Friday afternoon)
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
20
• TCV parameters and capabilities• Scientific mission and guidelines• Technical progress• Scientific highlights
Torque-free generation and transport of rotation
Particle and energy transport, turbulence Advanced real-time control Alternative confinement topologies
• Summary and outlook
Outline
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
21
Real-time control in TCV• All algorithms developed in powerful and
intuitive Simulink environment• Real-time nodes generate C code
automatically from Simulink
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Profile control with ECRH
J.I. Paley et al, PPCF 51, 124041 (2009)F. Felici, Ph.D. thesis (2011)
• Based on soft X-ray profile• Simple system with 2 actuators: on-
and off-axis ECRH powers to control amplitude and width
• Model parametrized through System Identification from random binary modulation of the EC power
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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Profile peak amplitude
Profile control with ECRH
J.I. Paley et al, PPCF 51, 124041 (2009)F. Felici, Ph.D. thesis (2011)
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
24
• TCV parameters and capabilities• Scientific mission and guidelines• Technical progress• Scientific highlights
Torque-free generation and transport of rotation
Particle and energy transport, turbulence Advanced real-time control Alternative confinement topologies
• Summary and outlook
Outline
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
25
The “snowflake” divertor
• 2nd order null point (Bq=0, Bq=0)• Six separatrix branches, four divertor legs• Increased flux expansion and connection
lengthmay alleviate divertor heat loads
• Snowflake (SF) is a point along a continuumfrom SF+ to SF-
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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The snowflake divertor in TCVSF+ SF SF-
F. Piras et al, PPCF 51 055009 (2009)
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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SFcompared to
single-null:• similar L-H threshold
SFcompared to
single-null:• similar L-H threshold• 2-3× slower ELMs
Snowflake H-modeSF compared to single-null:• 2-3× slower (type-I) ELMs• only 20-30% more energy loss per ELM
F. Piras et al, PRL 105, 155003 (2010)B. Labit et al, EXC/P8-08
Promising scaling for average power loss
B. Labit et al, EXC/P8-08 (Friday afternoon)
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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• Studies aligned with ITER requirements: spontaneous generation and transport of
momentum particle and energy transport effect of shape on turbulence real-time profile and MHD control
• Concept improvement and theory testing: new mechanism for turbulent momentum
transport snowflake divertor in L- and H-mode
Summary
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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• Up to 3 MW NBI heating• Up to 3 MW additional X3 ECRH heating• Refurbished LFS first wall for increased power
handling• In-vessel ergodization and error-field coils
for ELM control
Outlook: major upgrades
TCV research is built on unique flexibilityin ECRH and plasma shaping
further empower these unique characteristics
diversify and expand operational domain
S. Coda, 23rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010Progress and scientific results in TCV
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• TCV EXS/P2-17: O. Sauter et al, “Effects of ECH/ECCD on tearing modes in
TCV and link to rotation profile”, Tue pm EXC/P4-01: B.P. Duval et al, “Momentum transport in TCV across
sawteeth events”, Wed pm EXC/P8-08: B. Labit et al, “Transport and turbulence with innovative
plasma shapes in the TCV tokamak”, Fri pm EXC/P8-13: Y. Martin et al, “Impurity transport in TCV: neoclassical and
turbulent contributions”, Fri pm• Fusion technology
FTP/P1-16: N. Baluc et al, “From materials development to their test in IFMIF: an overview”, Tue am
• JET THS/9-1: J.P. Graves et al, “Sawtooth control relying on toroidally
propagating ICRF waves”, Sat am EXW/P7-27: D.S. Testa et al, “Recent JET experiments on Alfvén
eigenmodes with intermediate toroidal mode numbers: measurements and modelling, Fri am
• Basic plasma physics EXC/P8-09: A. Fasoli et al, “Turbulence and transport in simple
magnetized toroidal plasmas”, Fri pm
CRPP contributions