Neutral beam heating on the TCV tokamak

Karpushov, A.; Chavan, R.; Coda, S.; Давыденко, В. И.; Dolizy, F.; Dranitchnikov, A. N.; Duval, B. P.; Ivanov, A. A.; Fasel, D.; Fasoli, A.; Kolmogorov, V. V.; Lavanchy, P.; Llobet, X.; Marlétaz, B.; Marmillod, P.; Martin, Yves; Merle, A.; Pérez, A.; Sauter, O.; Siravo, U.; Shikhovtsev, I. V.; Сорокин, А. В.; Toussaint, M.

doi:10.1016/j.fusengdes.2017.02.076

Cited by 42 publications

(29 citation statements)

References 9 publications

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“…The goal of future studies will be to complement these observations with measurements from additional diagnostics to determine the relation between divertor volume and radiated power and to perform a detailed power balance, and to extend these studies to the forward field direction and scenarios with additional heating and H-mode. This will benefit from the fact that all the geometries developed in this work are compatible with the recently installed 1MW neutral beam heating system at TCV [63].…”

Section: Discussionmentioning

confidence: 99%

Results from recent detachment experiments in alternative divertor configurations on TCV

et al. 2017

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Divertor detachment is explored on the TCV tokamak in alternative magnetic geometries. Starting from typical TCV single-null shapes, the poloidal flux expansion at the outer strikepoint is varied by a factor of 10 to investigate the X-divertor characteristics, and the total flux expansion is varied by 70% to study the properties of the super-X divertor. The effect of an additional X-point near the target is investigated in X-point target divertors. Detachment of the outer target is studied in these plasmas during Ohmic density ramps and with the ion ∇B drift away from the primary X-point. The detachment threshold, depth of detachment, and the stability of the radiation location are investigated using target measurements from the wall-embedded Langmuir probes and two-dimensional CIII line emissivity profiles across the divertor region, obtained from inverted, toroidally-integrated camera data. It is found that increasing poloidal flux expansion results in a deeper detachment for a given line-averaged density and a reduction in the radiation location sensitivity to core density, while no large effect on the detachment threshold is observed. The total flux expansion, contrary to expectations, does not show a significant influence on any detachment characteristics in these experiments. In X-point target geometries, no evidence is found for a reduced detachment threshold despite a Nuclear Fusion Results from recent detachment experiments in alternative divertor configurations on TCVInternational Atomic Energy Agency a See the author list of 'Overview of progress in European Medium Sized Tokamaks towards an integrated plasma-edge/wall solution' by H. Meyer et al, to be published in the Nuclear Fusion

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Section: Discussionmentioning

confidence: 99%

Results from recent detachment experiments in alternative divertor configurations on TCV

et al. 2017

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“…TCV has a flexible set of magnetic coils that enable the creation of a wide range of plasma configurations. Electron cyclotron resonance heating and neutral beam injection 35 systems provide external heating and current drive, as used in the experiment in Fig. 3b .…”

Section: Methodsmentioning

confidence: 99%

Magnetic control of tokamak plasmas through deep reinforcement learning

Degrave

Felici

Buchli

et al. 2022

Nature

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411

218

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Nuclear fusion using magnetic confinement, in particular in the tokamak configuration, is a promising path towards sustainable energy. A core challenge is to shape and maintain a high-temperature plasma within the tokamak vessel. This requires high-dimensional, high-frequency, closed-loop control using magnetic actuator coils, further complicated by the diverse requirements across a wide range of plasma configurations. In this work, we introduce a previously undescribed architecture for tokamak magnetic controller design that autonomously learns to command the full set of control coils. This architecture meets control objectives specified at a high level, at the same time satisfying physical and operational constraints. This approach has unprecedented flexibility and generality in problem specification and yields a notable reduction in design effort to produce new plasma configurations. We successfully produce and control a diverse set of plasma configurations on the Tokamak à Configuration Variable1,2, including elongated, conventional shapes, as well as advanced configurations, such as negative triangularity and ‘snowflake’ configurations. Our approach achieves accurate tracking of the location, current and shape for these configurations. We also demonstrate sustained ‘droplets’ on TCV, in which two separate plasmas are maintained simultaneously within the vessel. This represents a notable advance for tokamak feedback control, showing the potential of reinforcement learning to accelerate research in the fusion domain, and is one of the most challenging real-world systems to which reinforcement learning has been applied.

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“…Power modulation at constant energy [4] is not possible in TCV because the minimum in modulation period is much longer than the fast ions' confinement time (τ≈10ms). This can be done modifying the extracted current at constant voltage, but this modifies as well the beam optics.…”

Section: Real-time Control Of Beam Powermentioning

confidence: 99%

“…Neutral Beam Heating (NBH) has widened the operational scenario of TCV reaching T i /T e >1 with record T i of 3.7 keV [4] (in H-mode), providing direct momentum input to the plasma and generating a large fast ion fraction to study wave-particle interaction phenomena of interest for burning plasmas.…”

Section: Introductionmentioning

confidence: 99%

Status, scientific results and technical improvements of the NBH on TCV tokamak

Vallar

Karpushov

Agostini³

et al. 2019

Fusion Engineering and Design

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The TCV tokamak contributes to physics understanding in fusion reactor research by a wide set of experimental tools, like flexible shaping and high power ECRH. A 1 MW, 25 keV deuterium heating neutral beam (NB) has been installed in 2015 and it was operated from 2016 in SPC-TCV domestic and EUROfusion MST1 experimental campaigns (~50/50%). The rate of failures of the beam is less than 5%. Ion temperatures up to 3.5 keV have been achieved in ELMy H-mode, with a good agreement with ASTRA predictive simulations. The NB enables TCV to access ITER-like β N values (1.8) and T e /T i ~1, allowing investigations of innovative plasma features in ITER relevant ELMy H-mode. The advanced Tokamak route was also pursued, with stationary, fully non-inductive discharges sustained by ECCD and NBCD reaching β N~1 .4-1.7. Real-time control of the NB power has been implemented in 2018 and presented together with the statistics of NB operation on the TCV. During commissioning, the NB showed unacceptable heating of the TCV beam duct, indicating a higher power deposition than expected on duct walls. A high beam divergence has been found by dedicated measurement of 3-D beam power density distribution with an expressly designed device (IR measurement on tungsten target).

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Neutral beam heating on the TCV tokamak

Cited by 42 publications

References 9 publications

Results from recent detachment experiments in alternative divertor configurations on TCV

Results from recent detachment experiments in alternative divertor configurations on TCV

Magnetic control of tokamak plasmas through deep reinforcement learning

Status, scientific results and technical improvements of the NBH on TCV tokamak

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