Publications by Henri Weisen | EPFL Graph Search

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The paper is dedicated to the characterisation of multi-strap ICRH antenna coupling to plasma. Relevance of traditional concept of coupling resistance to antennas with mutually coupled straps is revised and the importance of antenna port excitation consist ...

This paper presents the first application to real JET data of the new equilibrium code NICE which enables the consistent resolution of the inverse equilibrium reconstruction problem in the framework of non-linear free-boundary equilibrium coupled to the St ...

The electron temperature, pressure and density pro les from an extreme variety of shaped Ohmically heated sawtoothing plasmas in TCV ( Tokamak a Configuration Variable, B-T < 1.5T, R-0 = 0.88 m, a < 0.25 m) are compared to model predictions drawing from two bodies of theory. One of these is based on the assumption of stationary magnetic entropy and predicts sti toroidal current, and consequently Ohmically relaxed electron temperature pro les. The second theory is based on the assumption of approximate conse

Reliable algorithms for disruption avoidance and prediction are foreseen to play a fundamental role in the JET control system for the successful operation of the machine in the upcoming deuterium-tritium campaigns. The integration of such algorithms is exp ...

Alfven eigenmodes (AEs) driven by energetic alpha particles can lead to enhanced fast ion transport and losses, thereby degrading the plasma performance in ITER and future magnetic confinement fusion reactors. Unexpectedly, AEs with negative toroidal mode ...

The required heating power, P-LH, to access the high confinement regime (H-mode) in tritium containing plasmas is investigated in JET with ITER-like wall at a toroidal magnetic field of B-t = 1.8 T and a plasma current of I-p = 1.7 MA. PLH, also referred t ...

The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called ...

The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scra ...

A synthetic diagnostic has been developed for the JET lost alpha scintillator probe, based on the ASCOT fast ion orbit following code and the AFSI fusion source code. The synthetic diagnostic models the velocity space distribution of lost fusion products i ...

Recent studies (Maggi et al 2015 Nucl. Fusion 55 113031; Maggi et al 2017 Nucl. Fusion 57 116012) have shown that on JET with the Be/W ITER-like wall (JET-ILW) in high beta discharges with high D-2 gas rates, the inter-ELM temperature pedestal growth is sa ...

Ohmic H-mode has been regularly obtained on the TCV tokamak. This paper describes the change in magnetic activity occuring at the transition, the coherent activity during H-mode, a brief description of the dithering phase, and the activity associated with large and grassy ELMs.

A 'standard', single null lower diverted discharge has been developed to enable continuous monitoring of the first wall conditions and to characterise the effectiveness and influence of wall conditioning in the TCV tokamak. Measurements over a period encompassing nearly 2000 ohmic discharges of varying configuration and input power show the global confinement time and main plasma impurity concentrations to be good general indicators of the first wall condition, whilst divertor target profiles demonstrate st

Moderately peaked electron density profiles are observed in virtually all plasma conditions in TCV. The existence of an anomalous pinch is unambiguously demonstrated by the observation of peaked density profiles in stationary, fully relaxed, fully current driven electron cyclotron current drive (ECCD) discharges with V-loop = 0. The behaviour of the density profiles from a database of 300 Ohmic L- and H-mode, as well as electron cyclotron heating and ECCD discharges, is compared to predictions of models bas

A power-balance model, with radiation losses from impurities and neutrals, gives a unified description of the density limit (DL) of the stellarator, the L-mode tokamak, and the reversed field pinch (RFP). The model predicts a Sudo-like scaling for the stel ...

This paper examines the possibility of using the principle of conservation of canonical momentum applied to heavy ion beam orbits to obtain an estimate of the local poloidal flux at the position of ionization in a tokamak plasma. The presence of a nonaxisy ...

Post mortem analysis shows that mid and high atomic number metallic impurities are present in deposits on JET plasma facing components with the highest amount of Ni and W, and therefore the largest sink, being found at the top of the inner divertor. Source ...

The TCV tokamak contributes to the physics understanding of fusion plasmas, broadening the parameter range of reactor relevant regimes, by investigations based on an extensive use of the existing main experimental tools: flexible shaping and high power rea ...

The energy confinement time of TCV Ohmic, L-mode discharges is observed to depend strongly on the plasma shape, improving slightly with elongation and degrading strongly as triangularity is increased from zero to positive values. The thermal conductivity of these plasmas is found to be independent of the shape. This observation, combined with geometrical effects on the temperature gradient and a degradation with increasing input energy flux, can explain the observed variation in the energy confinement time.

The effects of plasma shape on confinement and sawtooth stability are studied for positive and negative discharge triangularity and for different elongations with 1.5 MW centrally deposited ECH power

The recently developed Monte-Carlo code ERO2.0 is applied to the modelling of limited and diverted discharges at JET with the ITER-like wall (ILW). The global beryllium (Be) erosion and deposition is simulated and compared to experimental results from pass ...

Henri Weisen

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ICRH antenna &ITS&IT-matrix measurements and plasma coupling characterisation at JET

Equilibrium reconstruction at JET using Stokes model for polarimetry

Evidence for the role of magnetic entropy and turbulent equipartition in stationary Ohmic tokamak discharges

A First Analysis of JET Plasma Profile-Based Indicators for Disruption Prediction and Avoidance

Evidence for Alfven eigenmodes driven by alpha particles in D-He-3 fusion experiments on JET

The role of isotope mass and transport for H-mode access in tritium containing plasmas at JET with ITER-like wall

Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall

Synthetic diagnostic for the JET scintillator probe lost alpha measurements

Inter-ELM evolution of the edge current density in JET-ILW type I ELMy H-mode plasmas

Mhd Activity During H-Mode Discharges on the Tcv Tokamak

Divertor target profiles and recycling studies in TCV single null lower standard discharges

Observation and empirical modelling of the anomalous particle pinch in TCV

A power-balance model of the density limit in fusion plasmas: application to the L-mode tokamak

On The Possibility Of Using A Heavy Ion Beam Probe For Local Poloidal Flux Measurements In A Tokamak

Deposition of impurity metals during campaigns with the JET ITER-like Wall

A scoping study of the application of neutral beam heating on the TCV tokamak

Influence of plasma shape on transport in the TCV Tokamak

Energy Confinement in Shaped TCV Plasmas with Electron Cyclotron Heating

Beryllium global erosion and deposition at JET-ILW simulated with ERO2.0