Full absorption of third harmonic ECH in TCV tokamak plasmas in the presence of second harmonic ECCD

Alberti, S.; Goodman, T. P.; Henderson, M.; Manini, A.; Moret, J.M.; Gomez, P.; Blanchard, P.; Coda, S.; Sauter, O.; Peysson, Y.; Team, Tcv

doi:10.1088/0029-5515/42/1/306

Cited by 33 publications

(41 citation statements)

References 27 publications

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“…4 for 110 GHz and 170 GHz. The intersection between the single particle resonant energies for the X2 and X3 waves defines the same radial position where both waves can interact with electrons of the same kinetic energy, but there is no intersection for 110 GHz and 170 GHz in KSTAR like TcV case [1]. However, there is overlap resonance zone in 2-D as seen in raytracing and quasi-linear Fokker-Planck calculation in fig.…”

Section: Synergy Effectmentioning

confidence: 94%

“…But TcV experiment [1,2] showed the enhanced X3 absorption through the synergetic effect of the X3 EC wave absorption when X2 electron cyclotron current drive (ECCD) is applied together. According to TcV experiments, there is evidence that some of the injected X3 EC power is absorbed by supra-thermal electrons in an energetic tail created by the X2 ECCD preheating.…”

Section: Introductionmentioning

confidence: 99%

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Study of Synergetic Effect of X2 and X3 EC Wave in KSTAR

Bae

Decker

Jeong

et al. 2015

EPJ Web of Conferences

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Abstract. An experimental study of the X-mode absorption at the second and the third harmonic frequencies has been performed in KSTAR tokamak. The X2 EC frequency is 110 GHz and the X3 EC frequency is 170 GHz at the nominal KSTAR operating toroidal magnetic field. From the 1-D model of the synergetic effect, the X3 cold resonance should lie at low field side with the X2 cold resonance at the high field side to meet the condition which both X2 and X3 EC waves interact with the same resonant electron at the same radial position. However, 170 GHz X3 cold resonance lies at the high field side with distance of 54 mm from the X2 cold resonance position in KSTAR. This paper presents the study of the synergetic effect of X3 absorption by the X2 ECCD with a scheme of two beam target positions at the same flux surface by scanning the poloidal and toroidal beam injection angles to enhance X3 absorption even in the low temperature plasma in KSTAR. For this study, the3D relativistic ray/tracing and Fokker-Planck codes C3PO/LUKE is used for the quantitative prediction of its synergetic effect. The C3PO/LUKE codes are appropriate for X2 and X3 synergy calculations as the distribution function can be calculated with either one or both waves affecting the absorption rate of each other. This paper also introduces the future ECH system upgrade plan.

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Section: Synergy Effectmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Study of Synergetic Effect of X2 and X3 EC Wave in KSTAR

Bae

Decker

Jeong

et al. 2015

EPJ Web of Conferences

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“…6), when the new dualfrequency gyrotron will be operational, the transmission lines of the three 118GHz gyrotron will be reconfigured for low-field side injection using the existing X2 launchers. This configuration has been used and validated during the first X3 heating experiments [5].…”

Section: X3 Single-pass Absorption Propertiesmentioning

confidence: 99%

Recent progress in the upgrade of the TCV EC-system with two 1MW/2s dual-frequency (84/126GHz) gyrotrons

et al. 2017

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Abstract. The upgrade of the EC-system of the TCV tokamak has entered in its realization phase and is part of a broader upgrade of TCV. The MW-class dual-frequency gyrotrons (84 or 126GHz/2s/1MW) are presently being manufactured by Thales Electron Devices with the first gyrotron foreseen to be delivered at SPC by the end of 2017. In parallel to the gyrotron development, for extending the level of operational flexibility of the TCV EC-system the integration of the dual-frequency gyrotrons adds a significant complexity in the evacuated 63.5mm-diameter HE 11 transmission line system connected to the various TCV low-field side and top launchers. As discussed in [1], an important part of the present TCV-upgrade consists in inserting a modular closed divertor chamber. This will have an impact on the X3 top-launcher which will have to be reduced in size. For using the new compact launcher we are considering employing a Fast Directional Switch (FADIS), combining the two 1MW/126GHz/2s rf-beams into a single 2MW rf-beam.

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“…The X3 absorption in these discharges is enhanced by the large elongation, 16 increased central density, and generation of a fast electron tail by co-ECCD, whose role in absorption has been previously demonstrated on TCV. 18 When the X3 deposition is optimized for the high elongation discharge, the DML diagnostic measures up to 100% absorption using modulation of the EC power. TORAY-GA calculates ϳ70% absorption in these discharges.…”

Section: Absorption Of Top Launched X3mentioning

confidence: 99%

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

et al. 2003

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In noninductively driven discharges, 0.9 MW second harmonic ͑X2͒ off-axis co-electron cyclotron current drive deposition is combined with 0.45 MW X2 central heating to create an electron internal transport barrier ͑eITB͒ in steady plasma conditions resulting in a 1.6-fold increase of the confinement time ( Ee ) over ITER-98L-mode scaling. The eITB is associated with a reversed shear current profile enhanced by a large bootstrap current fraction ͑up to 80%͒ and is sustained for up to 10 current redistribution times. A linear dependence of the confinement improvement on the product of the global shear reversal factor (q 0 /q min ) and the reversed shear volume ( q-min 2 ) is shown. In other discharges heated with X2 the sawteeth are destabilized ͑respectively stabilized͒ when heating just inside ͑respectively outside͒ the qϭ1 surface. Control of the sawteeth may allow the avoidance of neoclassical tearing modes that can be seeded by the sawtooth instability. Results on H-mode and highly elongated plasmas using the newly completed third harmonic ͑X3͒ system and achieving up to 100% absorption are also discussed, along with comparison of experimental results with the TORAY-GA ray tracing code ͓K. Matsuda, IEEE Trans. Plasma Sci. PS-17, 6 ͑1989͒; R. H. Cohen, Phys. Fluids 30, 2442 ͑1987͔͒.

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Full absorption of third harmonic ECH in TCV tokamak plasmas in the presence of second harmonic ECCD

Cited by 33 publications

References 27 publications

Study of Synergetic Effect of X2 and X3 EC Wave in KSTAR

Study of Synergetic Effect of X2 and X3 EC Wave in KSTAR

Recent progress in the upgrade of the TCV EC-system with two 1MW/2s dual-frequency (84/126GHz) gyrotrons

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

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