ICRH simulations for the Wendelstein 7-X stellarator

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Simulating the most external plasma region of a tokamak, the scrape-off layer (SOL), is of crucial importance in the way toward a fusion reactor as heat load on the vessel wall, impurity generation, overall plasma confinement, all depend on the plasma dynamics in this region. In the last few years a numerical code, GBS, has been developed for solving the drift-reduced Braginskii equations (DRBE), which describe turbulence in the tokamak SOL. In the present work, we re-formulate the DRBE in a general form th

The first-principle understanding of the processes in the Scrape-Off-Layer (SOL) of a tokamak is crucial for the development of a thermonuclear reactor. Since the plasma temperature in the SOL is rather low, the plasma is typically not fully ionized, and the neutral atoms play an important role in determining the SOL regimes. We have derived a kinetic model for neutral atoms in the SOL that contains the fundamental elements of neutral dynamics, while remaining relatively simple. The model has been coupled t

Turbulence in the scrape-off-layer (SOL) of magnetic fusion devices is one of the most outstanding issues in magnetic fusion. This open fied lines region determines the boundary condition of the core plasma and controls the plasma refueling, heat losses and impurity dynamics, therefore governing the fusion power output of the entire device. In this work, we present the global fluid code GBS [Ricci et al., Plasma Phys. Control. Fusion 54, 124047, 2012]. It employs a 5 field drift-reduced Braginskii model for

Earthing of electrical installations is mainly governed by safety rules. Electromagnetic compatibility also deals with earthing, among other circuit characteristics. Tokamaks are large-scale electrical installations that are known to generate large and low frequency magnetic fields as well as large and high frequency electric fields. Four European Tokamak installations have been investigated, from the earthing point of view, to identify appropriate techniques to earth the electrical equipment and to provide

This paper reports on the results of recent experiments performed on the JET tokamak on Alfven Eigenmodes (AEs) with toroidal mode number (n) in the range |n|=3-15. The stability properties of these medium-n AEs are investigated experimentally using a set of compact in-vessel antennas, providing a direct and real-time measurement of the frequency, damping rate and amplitude for each individual toroidal mode number. First, we describe the development of a new algorithm for real-time mode detection and discri

To ensure sufficient divertor target lifetime, the loss in plasma stored energy due to ELMs in ITER should be restricted to Delta W-ELM

Four of the 16 ITER upper port plugs will be devoted to electron cyclotron resonance heating (ECRH) in order to control the magneto-hydrodynamic (MHD) instabilities. In order to achieve the stabilisation of the neoclassical tearing modes (NTM) and sawtooth oscillation, a deposition of a very localized and peaked current density profile over a broad poloidal steering range is required. In the present optical configuration eight 2MW mm-wave beams enter each of the four upper launchers (UL) through waveguides

Advanced tokamak regimes obtained in ASDEX Upgrade, DIII-D, FF-U, JET, JT-60U, TCV and Tore Supra experiments are assessed both in terms of their fusion performance and capability for ultimately reaching steady-state using data from the international internal transport barrier database. These advanced modes of tokamak operation are characterized by an improved core confinement and a modified current profile compared to the relaxed Ohmically driven one. The present results obtained in these experiments are s

Magnetic reconnection in collisionless magnetohydrodynamic plasmas is studied under controlled conditions in toroidal X-line configurations formed in the center of the Versatile Toroidal Facility [J. Egedal , Rev. Sci. Instrum. 71, 3351 (2000)]. Profiles of key parameters are measured during driven reconnection pulses in the reproducible plasma discharges. The experimental results prove to be highly sensitive to the boundary conditions applied. In the configuration with "open" boundaries reconnection is fas

Recent results from the ASDEX Upgrade experimental campaigns 2001 and 2002 are presented. An improved understanding of energy and particle transport emerges in terms of a 'critical gradient' model for the temperature gradients. Coupling this to particle diffusion explains most of the observed behaviour of the density profiles, in particular, the finding that strong central heating reduces the tendency for density profile peaking. Internal transport barriers (ITBs) with electron and ion temperatures in exces

The Tokamak Configuration Variable (TCV) tokamak (R = 0.88 m, a < 0.25 m, B < 1.54 T) programme is based on flexible plasma shaping and heating for studies of confinement, transport, control and power exhaust. Recent advances in fully sustained off-axis electron cyclotron current drive (ECCD) scenarios have allowed the creation of plasmas with high bootstrap fraction, steady-state reversed central shear and an electron internal transport barrier. High elongation plasmas, kappa = 2.5, are produced at low nor

Measurement of the plasma generated diamagnetic flux on tokamak a configuration variable (TCV) is used to derive the plasma pressure, as on other magnetic confinement experiments. However, specificities of the device make the measurement more difficult: for passive stabilization of the vertical position of highly elongated plasmas, the vessel has a low electrical resistivity, leading to large image currents in the vessel. For the same reason the plasma must also be kept close to the conducting wall, so that

ICRH simulations for the Wendelstein 7-X stellarator

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A flexible numerical scheme for simulating plasma turbulence in the tokamak scrape-off layer

The interaction between neutral particles and turbulent plasma in the tokamak SOL

Recent numerical developments in scrape-off-layer global fluid simulations using the GBS code

ITER-Earthing

Measurement and Theoretical Modeling of the Damping Rate of Medium-N Toroidal Alfven Eigenmodes in JET

The impact of large ELMs on JET

Design and manufacturing of the ITER ECRH Upper launcher mirrors

Status of and prospects for advanced tokamak regimes from multi-machine comparisons using the 'International Tokamak Physics Activity' database

Experimental evidence of fast reconnection via trapped electron motion

Overview of ASDEX upgrade results

An overview of results from the TCV tokamak

Fast single loop diamagnetic measurements on the TCV tokamak