Recent results from the electron cyclotron heated plasmas in Tokamak à Configuration Variable (TCV)

Henderson, M.; Alberti, S.; Angioni, C.; Arnoux, G.; Behn, R.; Blanchard, P.; Bosshard, P.; Camenen, Y.; Coda, S.; Condrea, I.; Goodman, T. P.; Hofmann, F.; Hogge, J.‐P.; Karpushov, A.; Manini, A.; Martynov, An.; Moret, J.M.; Nikkola, P.; Nelson‐Melby, E.; Pochelon, A.; Porte, L.; Sauter, O.; Ahmed, Sharique; Andrèbe, Y.; Appert, K.; Chavan, R.; Degeling, A. W.; Duval, B. P.; Étienne, P.; Fasel, D.; Fasoli, A.; Favez, J.-Y.; Furno, I.; Horáček, J.; Isoz, P. F.; Joye, B.; Klimanov, I.; Lavanchy, P.; Lister, J.B.; Llobet, X.; Magnin, J.-C.; Marlétaz, B.; Marmillod, P.; Martin, Yves; Mayor, J. M.; Mylnar, J.; Paris, P.; Pérez, A.; Peysson, Y.; Pitts, R.A.; Raju, D.; Reimerdes, H.; Scarabosio, A.; Scavino, Edgar; Seo, S. h.; Siravo, U.; Sushkov, A. V.; Tonetti, G.; Tran, M.Q.; Weisen, H.; Wischmeier, M.; Zabolotsky, A.; Yhuang, G.

doi:10.1063/1.1562167

Cited by 27 publications

(17 citation statements)

References 18 publications

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“…ions with energies much larger than the background plasma. These can be generated by coherent or turbulent acceleration mechanisms or by shocks (Reames 1999;Perri and Zimbardo 2012), or directly by external sources (neutral beams and/or EC resonance heating (ECRH and current drive (CD), (Goodman et al 2003;Henderson et al 2003)) or nuclear reactions, as in the case of magnetic fusion devices. Common to all of these systems is the question of how plasma turbulence influences suprathermal particles and, in turn, how suprathermal particles influence turbulence.…”

Section: Suprathermal Ion Physicsmentioning

confidence: 99%

Plasma turbulence, suprathermal ion dynamics and code validation on the basic plasma physics device TORPEX

et al. 2015

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The TORPEX basic plasma physics device at the Center for Plasma Physics Research (CRPP) in Lausanne, Switzerland is described. In TORPEX, simple magnetized toroidal configurations, a paradigm for the tokamak scrape-off layer (SOL), as well as more complex magnetic geometries of direct relevance for fusion are produced. Plasmas of different gases are created and sustained by microwaves in the electron-cyclotron (EC) frequency range. Full diagnostic access allows for a complete characterization of plasma fluctuations and wave fields throughout the entire plasma volume, opening new avenues to validate numerical codes. We detail recent advances in the understanding of basic aspects of plasma turbulence, including its development from linearly unstable electrostatic modes, the formation of filamentary structures, or blobs, and its influence on the transport of energy, plasma bulk and suprathermal ions. We present a methodology for the validation of plasma turbulence codes, which focuses on quantitative assessment of the agreement between numerical simulations and TORPEX experimental data.

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Section: Suprathermal Ion Physicsmentioning

confidence: 99%

Plasma turbulence, suprathermal ion dynamics and code validation on the basic plasma physics device TORPEX

et al. 2015

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“…15 The initial Ohmic current is designed to be close to the value that the noninductive sources are able to drive. In typical scenarios with two 0.45 MW beams aimed at Ӎ 0.3, we set I p Ӎ 80-100 kA.…”

Section: Formation Of the Eitbmentioning

confidence: 99%

“…13͒ in the past few years has contributed to research along the advanced tokamak path from a unique perspective. 11,14,15 TCV plasmas are heated with secondharmonic ECRH at extremely high power densities ͑flux-surface averages in excess of 30 MW/ m 3 ͒ and at low plasma density ͑Շ3 ϫ 10 19 m −3 , dictated by ECRH accessibility͒. An important consequence of the low operational density is poor coupling between electrons and ions, which causes the electron temperature to be much larger than the ion temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The latter two parameters have reached 75% and 5, respectively, for durations exceeding 3 ϫ CRT . 15,19 ͑In this paper, the confinement enhancement will be characterized by the parameter H RLW , expressing the ratio of the electron energy confinement time eE to that predicted by the Rebut-LalliaWatkins scaling. 20 The latter is an excellent predictor of TCV L-mode confinement, which owing to the poor confinement properties of electrons is typically a factor of 2-3 lower than the ITER-L-98 scaling.…”

Section: Introductionmentioning

confidence: 99%

“…15,19 The discharge is initiated as a canonical Ohmic discharge. After the beginning of the current flat top, co-ECCD is applied off-axis, between = 0.2 and 0.5 ͑ being a normalized radial coordinate proportional to the square root of the enclosed plasma volume͒.…”

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High-bootstrap, noninductively sustained electron internal transport barriers in the Tokamak à Configuration Variable

Coda¹,

Goodman²,

Henderson³

et al. 2005

Physics of Plasmas

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Important ingredients of the advanced-tokamak route to fusion have been explored in depth in the Tokamak à Configuration Variable ͓F. Hofmann, J. B. Lister, M. Anton et al., Plasma Phys. Controlled Fusion 36, B277 ͑1994͔͒ over the past two years. Using a uniquely powerful and flexible electron-cyclotron resonance heating ͑ECRH͒ system as the primary actuator, fully noninductive, steady-state electron internal transport barrier discharges have been generated with an electron-energy confinement time up to five times longer than in L mode, poloidal ␤ up to 2.4, and bootstrap fraction up to 75%. Interpretative transport modeling confirms that the safety factor profile is nonmonotonic in these discharges. The formation of the barrier is a discrete event resulting in rapid and localized confinement improvement consistent with the time and location of magnetic-shear reversal. In steady state, however, the confinement quality appears to depend on the current gradient in a broader negative-shear region enclosed by the barrier, improving with increasing shear: in particular, the width and depth of the barrier can be controlled and finely tuned, along a magnetohydrodynamic-stable path, by manipulating the current profile with ECRH ͑six independently steerable 0.45 MW launchers͒. The crucial role of the current profile has been clearly demonstrated by applying small Ohmic current perturbations which dramatically alter the properties of the barrier, enhancing or reducing the confinement with negative and positive current, respectively, with negligible Ohmic heating. These results are in agreement with theoretical estimates: first-principle-based numerical simulations of microinstability dynamics and turbulence-driven transport predict a substantial suppression of turbulence and anomalous energy diffusivity near the location of the minimum in the safety factor.

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Observation of inward and outward particle convection in the core of electron cyclotron heated and current driven plasmas in the Tokamak à Configuration Variable

Furno

Weisen

2003

Physics of Plasmas

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In the Tokamak à Configuration Variable [F. Hofmann, J.B. Lister, M. Anton et al., Plasma Phys. Controlled Fusion 36, B277 (1994)], inward or outward convection in the core of electron cyclotron heated and current driven plasmas is observed, depending on discharge conditions. In sawtoothing discharges with central electron cyclotron heating, outward convection is observed when a quasicontinuous m=1 kink mode is present, resulting in inverted sawteeth on the central electron density, while in the absence thereof, inward convection between successive sawtooth crashes leads to “normal” sawteeth. The occurrence of a kink mode depends sensitively on plasma triangularity. When sawteeth are stabilized with central co- or counterelectron cyclotron current drive, stationary hollow electron density profiles are observed in the presence of m=1 modes, while peaked or flat profiles are observed in magnetohydrodynamic quiescent discharges. The observation of peaked density profiles in fully electron cyclotron driven plasmas demonstrates that pinch processes other than the Ware pinch must be responsible for these phenomena.

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Recent results from the electron cyclotron heated plasmas in Tokamak à Configuration Variable (TCV)

Cited by 27 publications

References 18 publications

Plasma turbulence, suprathermal ion dynamics and code validation on the basic plasma physics device TORPEX

Plasma turbulence, suprathermal ion dynamics and code validation on the basic plasma physics device TORPEX

High-bootstrap, noninductively sustained electron internal transport barriers in the Tokamak à Configuration Variable

Observation of inward and outward particle convection in the core of electron cyclotron heated and current driven plasmas in the Tokamak à Configuration Variable

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