Model-based electron density estimation using multiple diagnostics on TCV

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An approach to analysis of time series of edge localized modes (ELMs) is proposed. It is based on the use of the autoregressive moving average model, which decomposes time series into deterministic and noise components. Despite the inclusion of nonlinearity in the model, the resulting deterministic equations for the ELM time series measured on Axially Symmetric Divertor Experiment Upgrade tokamak turn out to be linear. This contrasts with the findings on JAERI tokamak (JT-60U) and tokamak a configuration va

This paper shows the importance and feasibility of real-time tomography in fusion experiments for the example of soft X-ray (SXR) position measurements. The requirement of non-magnetic real-time diagnostics in low frequencies for ITER is discussed. This is illustrated by recent results of rapid tomographic inversion of SXR measurements on tokamak TCV. Comparison with the magnetic reconstruction data has not only shown the valuable resolution capabilities of both techniques, but also revealed a slight depend

Though helium plasmas are one option for the low activation phase of ITER, little effort has thus far been devoted to studying them in a large, diverted tokamak. A recent campaign on JET has therefore sought to address some of the important questions related to helium operation (He concentrations near 90%) in single null configuruations, particularly with regard to edge and divertor physics. This contribution compiles a selection of results from these experiments, in which, in each case, discharges have bee

A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, beta(Nonset), is increased. The scenario has been explored experimentally in the Joint European Torus (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance hav

Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak à Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuat

An electron cyclotron resonance heating (ECRH) system is presently under construction at Commissariat A l'Energie Atomique (CEA) Cadarache for the Tore Supra experiment. The generator is planned to be made of six gyrotrons giving RF waves with a frequency of 118 GHz and a unit power of 400 kW (500 kW) for a pulse length of 210 s (5 s); two of them are already installed: the prototype was first tested on various dummy loads and on plasma and the first series tube is still being tested on a CW load. The resul

SULTAN, the world wide unique, high field, large bore test facility. has been built as European contribution to the development program for ITER, The facility has primarily been devoted to the qualification of full-size cable-in-conduit-conductors (CICC) foreseen as potential candidates for use in the Central-Solenoid (CS) and the Toroidal-Field (TF) coils of ITER, Fields up to 11 T can be imposed to the vertically inserted CICC-Samples. Horizontal insertion of coiled long conductor samples is possible as d

Electrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed. Diffusion mechanisms have been stud

Ag(111) surface state electrons have been confined in symmetric and asymmetric Fabry-Perot resonators formed by two atomically parallel step edges. The local density of states in the resonators has been measured by means of low-temperature scanning tunneling spectroscopy and can perfectly be explained with a simple Fabry-Perot-like model. The energy dependent reflection amplitudes and scattering phase shifts of the different kinds of Ag(111) step edges have been determined with high accuracy. The model char

The absorption of power is studied with fluid and gyrokinetic plasma models, when Alfven resonances provide for a weak damping in a partially standing wave field. Examples chosen in slab and toroidal geometry show that the fluid predictions based on resonance absorption are generally very different from the Landau damping of mode-converted slow waves. They, in particular, suggest that the continuum damping of toroidal Alfven eigenmodes (TAE) and the power deposition profiles obtained in the ion-cyclotron ra

An analysis of the effect on the wall stabilization of external kink modes due to toroidally continuous gaps in the resistive wall is performed. The effects both with and without toroidal rotation are studied. For a high-beta equilibrium, the mode structure is localized on the outboard side. Therefore, outboard gaps greatly increase the growth rate when there is no rotation. For resistive wall stabilization by toroidal rotation, the presence of gaps has the same effect as moving the wall farther away, i.e.,

This paper presents an overview of results of the 1994/95 experimental campaign on JET with the new pumped divertor and draws implications for ITER in the areas of detached and radiative divertor plasmas, the use of beryllium as a divertor target the material, the confinement properties of discharges with the same dimensionless parameters (except for the dimensionless Larmor radius) as ITER and the effect of varying the toroidal magnetic field ripple in the ITER relevant range. Discharges with high fusion p

Model-based electron density estimation using multiple diagnostics on TCV

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Autoregressive moving average model for analyzing edge localized mode time series on Axially Symmetric Divertor Experiment (ASDEX) Upgrade tokamak

Present and perspective roles of soft X-ray tomography in tokamak plasma position measurements

Comparing scrape-off layer and divertor physics in JET pure He and D discharges

Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET

MHD stability limits in the TCV tokamak

The 118 GHz ECRH experiment on Tore Supra

Facility status and results on ITER full-size conductor tests in SULTAN

Stoichiometry and interdiffusion in PZT thin films studied by transmission electron microscopy

Confinement of surface state electrons in Fabry-Perot resonators

On resonance absorption and continuum damping

The effect of partial poloidal wall sections on the wall stabilization of external kink modes

JET results with the new pumped divertor and implications for ITER