Centre de Recherches en Physique des Plasmas EPFL, Association Euratom-Fédération Suisse, Lausanne, Switzerland S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in the TCV tokamak for the TCV team* S. Coda *including collaborating institutions: S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010

Progress 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 3 TCV R = 0.88 m, a = 0.25 m I p < 1 MA, B T < 1.54 T  < 2.8, -0.6 <  < MW ECRH power, 7 steerable launchers ×4 ×2

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 4 Experiments in preparation for ITER Alternative configurations, tokamak concept improvement Scientific guidelines of the TCV program

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 5 ITER preparation + alternative paths Multiple steerable EC launchers, r/t control NTM stabilization

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 6 ITER preparation + alternative paths Flexible shaping

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 7 Highlights of technical progress ×Improved charge exchange spectroscopy resolution (from 2 to 1 cm) + sensitivity (5-10×): T i, v , v   n C New digital real-time network to control coils and EC systems  potential to use massively multichannel diagnostics

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 9 Symmetry breaking  toroidal momentum transport by turbulence New 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 v ,  v , or up-down asymmetry (Y. Camenen et al, PRL 2009)

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 10 Same B , I p inward outward Turbulent momentum transport Y. Camenen et al, PRL 105, (2010) Radial turbulent momentum flux changes sign as expected from up-down flip  v  varies most at edge where asymmetry is greatest  B drift BB Direction of radial flux should reverse with B  sign, I p sign, up-down flip All reversals have been confirmed by experiment

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 11 observed systematically in TCV L-modes (no torque) at low to moderate current (q edge >3), v  is counter-current in core central rotation is limited by sawtooth crashes imparting a co-current spin v  changes sign at high current and density Spontaneous plasma rotation A. Fasoli, IAEA 2008 overview experiments performed to 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 2006 B.P. Duval et al, PPCF 2007 B.P. Duval et al, PoP 2008

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 12 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 13 Slightly hollow inside the mixing radius......to the point of changing sign at high enough current Average effect of sawteeth on rotation Self-similar gradients outside the mixing radius

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 14 Influencing rotation with ECRH through sawteeth EC power inside mixing radius hollows out v  profile Similar to I p increase: consistent with effect of current profile peaking on sawteeth O. Sauter et al, EXS/P2-17

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 16 Stronger flattening by sawteeth for impuritiesStronger peaking for impurities than for electrons Sawteeth affect particle transport similarly to momentum transport ElectronsCarbon ions Similar edge gradients Y. Martin et al, EXC/P8-13 (Friday afternoon)

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 17 The effect of shape on turbulence Triangularity strongly influences transport: confinement of EC-heated  =-0.4 plasmas is up to twice as good as for  =+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 2007 A. Marinoni et al, PPCF 2009

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 18 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 kHz range

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 19 Longer correlation length at  >0 larger random-walk step, consistent with more transport B. Labit et al, EXC/P8-08 (Friday afternoon)

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 22 Profile control with ECRH J.I. Paley et al, PPCF 51, (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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 23 Profile peak amplitude Profile control with ECRH J.I. Paley et al, PPCF 51, (2009) F. Felici, Ph.D. thesis (2011)

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 25 The “snowflake” divertor 2 nd order null point (B  =0,  B  =0) Six separatrix branches, four divertor legs Increased flux expansion and connection length may alleviate divertor heat loads Snowflake (SF) is a point along a continuum from SF+ to SF-

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 26 The snowflake divertor in TCV SF+SFSF- F. Piras et al, PPCF (2009)

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 27 SF compared to single-null: similar L-H threshold SF compared to single-null: similar L-H threshold 2-3× slower ELMs Snowflake H-mode SF compared to single-null: 2-3× slower (type-I) ELMs only 20-30% more energy loss per ELM F. Piras et al, PRL 105, (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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 28 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, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 29 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 flexibility in ECRH and plasma shaping  further empower these unique characteristics  diversify and expand operational domain

S. Coda, 23 rd IAEA Fusion Energy Conference, OV/5-2, Daejeon, 13 October 2010 Progress and scientific results in TCV 30 TCVTCV  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 technologyFusion technology  FTP/P1-16: N. Baluc et al, “From materials development to their test in IFMIF: an overview”, Tue am JETJET  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 physicsBasic plasma physics  EXC/P8-09: A. Fasoli et al, “Turbulence and transport in simple magnetized toroidal plasmas”, Fri pm CRPP contributions