H-mode physics studies on TCV supported by the EUROfusion pedestal database

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JT-60SA is the world’s largest superconducting tokamak in operation jointly built and exploited by Europe and Japan in the framework of the Broader Approach. JT-60SA aims at addressing some of the technological and physics challenges, such as the long pulse steady-state plasma operation at high beta. The start-up of JT-60SA, which culminated in the first JT-60SA plasma achieved on 23 October 2023 and Operation-1 (OP-1) until the end of 2023, including the achievement of >1 MA diverted plasmas, paves the way

The EC Upper Launcher (UL) and Ex-vessel waveguide (EW) are integral components of the ITER Electron Cyclotron (EC) system [1], which plays a key role in achieving and maintaining the high temperatures required for nuclear fusion within the tokamak, providing plasma heating and current drive, and magnetohydrodynamics (MHD) stabilization, which are crucial for ITER’s operational success. The EC system is increasingly becoming the reference mechanism for plasma heating in both present and future devices. Nota

The Swiss Plasma Center is upgrading the TCV tokamak to test a tightly baffled, long-legged divertor (TBLLD), a novel concept that promises to enhance power exhaust capabilities with minimal modification to the magnetic configuration [1,2]. Simulations using the SOLPS-ITER code indicate that a TBLLD can improve TCV’s power exhaust capability by an order of magnitude compared to the unbaffled configuration [2]. Tight baffling sustains a high poloidal neutral density gradient, thereby, increasing the neutral

This contribution will present a feasibility study and conceptual design of a tangential phase-contrast imaging (PCI) diagnostic for the new JT60SA tokamak. PCI is a well-known technique for measuring density fluctuations. Tangential launching, combined with an appropriate spatial filtering technique, affords the measurement highly improved spatial localization, as demonstrated in particular on the TCV tokamak. Tangential ports of 20cm diameter are envisioned to be used on JT60SA, obviating the need to moun

In a multi-gyrotron system such as the one presently designed for the ITER ECH & ECCD system, stray magnetic fields can significantly alter the operational capabilities of the global system. A numerical study was carried out within the European Gyrotron Consortium (EGYC) to assess the importance of the different effects and their impact on the gyrotron operation. Using the Ariadne++ 3D code, and based on the geometrical layout of the ITER-EC system, the effect of the ITER stray magnetic field combined toget

A detailed study of the operational capabilities of the W7-X/1MW gyrotron operated at 126GHz/TE26,7 is presented. This study is associated with the foreseen upgrade of TCV in which it is planned to add to the present EC system 3MW of additional RF power bringing the total EC-power to 7.5MW. This study is extended to a possible operation of the gyrotron at the ITER relevant frequency of 168GHz in the TE35,9 mode without implementing any further modification neither in the gyrotron nor in the gyrotron superco

All tokamak experiments using ECCD require setting of the beam elliptical polarization for proper coupling to the plasma. This is done either in the matching optics unit (MOU) at the output of the gyrotron, or in a couple of miter bends of the transmission line. Similarly, oblique ECE receivers require selection of the correct elliptical polarization to provide localized measurements. For the TCV tokamak at the CRPP, gyrotron and oblique-ECE polarizers are characterized during either high- or low- power tes

The main objective of the ITER ECRH Upper Launcher (UL) is to control magnetohydrodynamic (MHD) activity: sawtooth oscillations and neoclassical tearing modes. 170GHz RF beams are oriented and focused to obtain a maximum overlapping of the waists of all the beams throughout the deposition location range in the plasma. The steering of the beams is done using 8 independent steering mirrors (SM) placed in the front par t of each one of the four dedicated por t plugs. Accurate and rapid control of the SMs for d

Long period sawteeth have been observed to result in low-beta triggering of neo-classical tearing modes, which can significantly degrade plasma confinement. Consequently, a detailed physical understanding of sawtooth behaviour is critical, especially for ITER where fusion-born a particles are likely to lead to very long sawtooth periods. Many techniques have been developed to control, and in particular to destabilize the sawteeth. The application of counter-current neutral beam injection (NBI) in JET has re

In burning plasma experiments, the very energetic alpha (alpha) particles resulting from a deuterium-tritium fusion reaction will be the dominant heating mechanism and will give rise to new physics issues. Recent experiments performed on the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] and aiming to investigate burning plasma physics are reported in this paper. In the presence of very energetic particles, the magnetohydrodynamic stability of plasmas is affected. Sawteeth

In a tokamak fusion reactor the energetic alpha particles will transiently stabilize the magnetohydrodynamic activity causing sawtooth oscillations. The crash events terminating long sawtooth free periods can provide seed islands for neoclassical tearing modes [O. Sauter et al., Phys. Rev. Lett. 88, 105001 (2002)]. To shorten the sawtooth periods localized current drive near the q=1 surface is a possibility. This Letter provides the first experimental evidence for the effectiveness of this method in the dif

Ion cyclotron heating and current drive at omega approximate to 2omega(cH) in JET deuterium plasmas with a hydrogen concentration n(H)/(n(D)+n(H)) in the range of 5-15% are analysed, comparing results of numerical computer modelling with experiments. Second harmonic hydrogen damping is found to be maximized by placing the resonance on the, low-field side (LFS) of the torus, which minimizes competing direct electron damping and parasitic high-harmonic D damping in the presence of D beams. The shape of the ca

Recent experiments at the Joint European Torus [Rebut , Fusion Eng. Des. 22, 7 (1993)] aim to improve confinement quality in high-confinement-mode (H-mode) plasmas at high densities. Energy confinement time as predicted by the International Thermonuclear Experimental Reactor ITER-H98(y,2) scaling at densities near or in excess of 85% of the Greenwald density limit scaling has been obtained by (i) strong plasma shaping (triangularity 0.35

The development of high power CW gyrotrons for ECRH heating of fusion relevant plasmas has been in progress for several years in a joint collaboration between different European research institutes and an industrial partner. Two development are on going, aiming, respectively, towards a 0.51-MW-210-s gyrotron at 118 GHz for the tokamaks TCV of CRPP (2 s pulse length) and Tore Supra of CEA (210 s pulse length), and towards a 1 MW-CW gyrotron at 140 GHz for the stellarator W7-X under construction in Greifswald

Fast particle driven instabilities are investigated at low toroidal field B-0 approximate to 1 T in tritium, deuterium and hydrogen plasmas. Tritium, deuterium and hydrogen neutral beams with energies of 160, 140 and 110 keV were injected, respectively, into tritium, deuterium and hydrogen plasmas. The destabilization of Alfven eigenmodes was observed during injection of tritium beams into a tritium plasma and during the injection of deuterium beams into a deuterium plasma but not during the injection of hy

Within the range of plasma shapes and plasma currents investigated, the electron confinement time, Tau_E increases with density, elongation and negative triangularity (-0.4

Planned experiments in the Joint European Torus [Plasma Physics and Controlled Fusion Research, Proceedings, 13th International Conference, Washington, D.C., 1990 (International Atomic Energy Agency, Vienna, 1991), Vol. 1, p. 27] (JET) with deuterium-tritium (D-T) plasmas require high fusion performance for alpha-particle heating studies and for investigation of isotope dependence in conditions relevant to the International Thermonuclear Experimental Reactor [Plasma Phys. Controlled Fusion 37, A19 (1995)].

Results from the first experiments to drive Alfven Eigenmodes (AEs) with antennas external to a tokamak plasma are presented. In ohmically heated plasma discharges, direct experimental measurements of the damping of toroidicity induced AEs (TAEs) have allowed an identification of different regimes corresponding to different dominant TAE absorption mechanisms with a wide range of damping rates, 10(-3) less than or equal to gamma/omega less than or equal to 10(-1). In plasmas heated by ion cyclotron resonance

H-mode physics studies on TCV supported by the EUROfusion pedestal database

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Overview of first JT-60SA plasma operation and plans in view of ITER and DEMO

The design of the EC Upper Launcher and Ex-vessel waveguide systems for ITER

Assessing the Tightly-Baffled, Long-Legged Divertor (TBLLD) concept in TCV

Tangential phase-contrast imaging for fluctuation measurements in JT–60SA: a conceptual study

Calculation of Stray Magnetic Field Effects on the Operation of the ITER Electron Cyclotron System

Design studies of the dual-frequency operation of the W7-X/140GHz/1MW gyrotron at 126GHz for TCV and 168GHz for ITER

Polarization Issues with High Power Injection and Low Power Emission in Fusion Experiments

Progress on the ITER Upper Launcher Control Systems

The physics of sawtooth stabilization

Studies of burning plasma physics in the Joint European Torus

Destabilization of fast-ion-induced long sawteeth by localized current drive in the JET tokamak

Analysis of ion cyclotron heating and current drive at omega approximate to 2 omega(cH) for sawtooth control in JET plasmas

High density, high performance high-confinement-mode plasmas in the Joint European Torus (JET)

European high-power CW gyrotron development for ECRH systems

Beam driven Alfven eigenmodes and fishbones in JET

Preliminary Confinement Studies during ECRH in TCV

High performance Joint European Torus (JET) plasmas for deuterium-tritium operation with the MkII divertor

Overview of alfven eigenmode experiments in jet