E. Viezzer
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View article: Linear and quasi-linear modeling in view of ELM control in MAST-U including effects of error fields
Linear and quasi-linear modeling in view of ELM control in MAST-U including effects of error fields Open
Edge localized modes (ELMs) pose a critical challenge to the safety and performance of plasma-facing components in tokamaks due to their periodic expulsion of heat and particles. This study investigates the behavior of various figures of m…
View article: Investigation of multi-ion heat and neoclassical transport using new edge main ion measurements at ASDEX Upgrade
Investigation of multi-ion heat and neoclassical transport using new edge main ion measurements at ASDEX Upgrade Open
This study provides new insights into multi-ion heat transport and the validation of neoclassical theory at the edge of H-mode plasmas. Utilizing a high-resolution main ion charge exchange recombination spectroscopy system, the first chara…
View article: Reducing turbulent transport in tokamaks by combining intrinsic rotation and the low momentum diffusivity regime
Reducing turbulent transport in tokamaks by combining intrinsic rotation and the low momentum diffusivity regime Open
Based on the analysis of a large number of high-fidelity nonlinear gyrokinetic simulations, we propose a novel strategy to improve confinement in spherical tokamak plasmas by combining up-down asymmetric flux surface shaping with the Low M…
View article: Impact of the plasma boundary on machine operation and the risk mitigation strategy on JET
Impact of the plasma boundary on machine operation and the risk mitigation strategy on JET Open
This work examines the separatrix and Scrape-off-Layer (SOL) characteristics in three scenarios on JET: the Quasi-Continuous Exhaust (QCE) regime, the ITER Baseline scenario, and the X-point Radiator (XPR) regime. All three scenarios are p…
View article: Progress in pedestal and edge physics: Chapter 3 of the special issue: on the path to tokamak burning plasma operation
Progress in pedestal and edge physics: Chapter 3 of the special issue: on the path to tokamak burning plasma operation Open
This paper describes the extensive progress that has been made in the understanding of tokamak pedestal physics since the 2007 publication of ‘Progress in the ITER Physics Basis’ (Ikeda 2007 Nucl. Fusion 47 E01–S500). It serves as Chapter …
View article: Experimental observations of fast-ion losses induced by neoclassical tearing modes in the MAST-U spherical tokamak
Experimental observations of fast-ion losses induced by neoclassical tearing modes in the MAST-U spherical tokamak Open
Neoclassical tearing modes (NTMs) have been identified as the most deleterious perturbations in high-performance plasmas at Mega Amp Spherical Tokamak Upgrade (MAST-U). They produce magnetic islands that flatten the electron temperature pr…
View article: The quasi-continuous exhaust regime in ASDEX Upgrade and JET
The quasi-continuous exhaust regime in ASDEX Upgrade and JET Open
The quasi-continuous exhaust (QCE) regime is a type-I ELM-free high confinement regime obtained at high plasma shaping and high separatrix density. A comparison with various ELM-free regimes in the literature is presented together with pot…
View article: EDA H-mode in ASDEX Upgrade: scans of heating power, fueling, and plasma current
EDA H-mode in ASDEX Upgrade: scans of heating power, fueling, and plasma current Open
Electron cyclotron resonance heating (ECRH) staircase discharges in strongly shaped plasmas were performed at the full-tungsten ASDEX Upgrade tokamak to investigate the enhanced D α (EDA) H-mode, a high-confinement regime without edge loca…
View article: The quasi-continuous exhaust regime in JET
The quasi-continuous exhaust regime in JET Open
The quasi-continuous exhaust (QCE) regime is a regime that is naturally type-I ELM-free. It combines the high density at the plasma edge needed for power exhaust with the high normalised energy confinement typical for H-mode operation. In …
View article: Hybrid hydrogen-electricity production using spherical tokamaks: a cost-driver sensitivity study and techno-economic analysis
Hybrid hydrogen-electricity production using spherical tokamaks: a cost-driver sensitivity study and techno-economic analysis Open
Hybrid fusion power plants, which produce both hydrogen and electricity, are proposed as a way to decarbonise the fossil-fuel-dominated primary energy market and improve plant economics. The main cost drivers of a fusion power plant based …
View article: Effect of energetic ions on edge-localized modes in tokamak plasmas
Effect of energetic ions on edge-localized modes in tokamak plasmas Open
View article: Velocity-space analysis of fast-ion losses measured in MAST-U using a high-speed camera in the FILD detector
Velocity-space analysis of fast-ion losses measured in MAST-U using a high-speed camera in the FILD detector Open
A fast-ion loss detector (FILD) was installed for the first time at the mega amp spherical tokamak—upgrade (MAST-U) spherical tokamak during its upgrade in 2021. A new CMOS camera was installed in the MAST-U FILD acquisition system to prov…
View article: Thermal helium beam diagnostic for 2D profile measurements in the divertor of ASDEX Upgrade
Thermal helium beam diagnostic for 2D profile measurements in the divertor of ASDEX Upgrade Open
A new thermal helium beam diagnostic has been implemented in the outer lower divertor of the ASDEX Upgrade tokamak. The purpose of this diagnostic is to measure two-dimensional profiles of electron density (ne) and temperature (Te) with hi…
View article: Performance prediction applying different reduced turbulence models to the SMART tokamak
Performance prediction applying different reduced turbulence models to the SMART tokamak Open
The SMall Aspect Ratio Tokamak (SMART) is currently being commissioned at the University of Seville and will be able to compare the performance of positive and negative triangularity plasmas at low aspect ratio. Predictive simulations have…
View article: Reducing turbulent transport in tokamaks by combining intrinsic rotation and the low momentum diffusivity regime
Reducing turbulent transport in tokamaks by combining intrinsic rotation and the low momentum diffusivity regime Open
Based on the analysis of a large number of high-fidelity nonlinear gyrokinetic simulations, we propose a novel strategy to improve confinement in spherical tokamak plasmas by combining up-down asymmetric flux surface shaping with the Low M…
View article: MHD stability analysis against pressure and current-driven modes in the SMall Aspect Ratio Tokamak
MHD stability analysis against pressure and current-driven modes in the SMall Aspect Ratio Tokamak Open
Linear magnetohydrodynamic (MHD) simulations for the SMall Aspect Ratio Tokamak (SMART) have been carried out for the first time, for both positive (PT) and negative triangularity (NT) shaped plasmas using the MARS-F code. The MHD stabilit…
View article: Design of a Thomson scattering diagnostic for the SMall Aspect Ratio Tokamak (SMART)
Design of a Thomson scattering diagnostic for the SMall Aspect Ratio Tokamak (SMART) Open
We describe the design of a Thomson scattering (TS) diagnostic to be used on the SMall Aspect Ratio Tokamak (SMART). SMART is a spherical tokamak being commissioned in Spain that aims to explore positive triangularity and negative triangul…
View article: Physics of the low momentum diffusivity regime in tokamaks and its experimental applicability
Physics of the low momentum diffusivity regime in tokamaks and its experimental applicability Open
Strong $E\times B$ plasma flow shear is beneficial for reducing turbulent transport. However, traditional methods of driving flow shear do not scale well to large devices such as future fusion power plants. In this paper, we use a large nu…
View article: First observation of RMP ELM mitigation on MAST Upgrade
First observation of RMP ELM mitigation on MAST Upgrade Open
The first experimental attempts at controlling edge localised modes (ELMs) via the application of resonant magnetic perturbations on the MAST Upgrade tokamak are reported. Using the linear MHD model MARS-F, the phase shift between the uppe…
View article: Visible core spectroscopy at <b>Wendelstein 7-X</b>
Visible core spectroscopy at <b>Wendelstein 7-X</b> Open
This paper presents an overview of recent hardware extensions and data analysis developments to the Wendelstein 7-X visible core spectroscopy systems. These include upgrades to prepare the in-vessel components for long-pulse operation, nin…
View article: Design and development of the magnetic diagnostic systems for the first operational phase of the SMART tokamak
Design and development of the magnetic diagnostic systems for the first operational phase of the SMART tokamak Open
A set of magnetic diagnostics has been designed, manufactured, and calibrated for the first operational phase of the small aspect ratio tokamak. The sensor suite comprises of Rogowski coils; 2D magnetic probes; and poloidal, saddle, and di…
View article: Design of a Thomson scattering diagnostic for the SMART tokamak
Design of a Thomson scattering diagnostic for the SMART tokamak Open
We describe the design of a Thomson scattering (TS) diagnostic to be used on the SMall Aspect Ratio Tokamak (SMART). SMART is a spherical tokamak being commissioned in Spain that aims to explore positive triangularity (PT) and negative tri…
View article: Non-linear MHD investigations of high-confinement regimes without type-I ELMs in ASDEX Upgrade and JT-60SA
Non-linear MHD investigations of high-confinement regimes without type-I ELMs in ASDEX Upgrade and JT-60SA Open
Large edge localised modes (ELMs) would cause an unacceptable reduction of material lifetime in future large tokamaks due to the significant amount of energy expelled from the magnetically confined region towards the plasma facing componen…
View article: Poloidal structure of the edge parallel flow in H-mode, L-mode and I-mode confinement regimes
Poloidal structure of the edge parallel flow in H-mode, L-mode and I-mode confinement regimes Open
Impurity profiles have been measured with the edge high field side (HFS) and low field side (LFS) charge exchange recombination spectroscopy suite at ASDEX Upgrade enabling the study of the poloidal structure of the edge parallel flow in H…
View article: Physical insights from the aspect ratio dependence of turbulence in negative triangularity plasmas
Physical insights from the aspect ratio dependence of turbulence in negative triangularity plasmas Open
In this work, we study the impact of aspect ratio (the ratio of major radius R 0 to minor radius r) on the confinement benefits of negative triangularity (NT) plasma shaping. We use high-fidelity flux tube gyrokinetic GENE simula…
View article: Experiments and gyrokinetic simulations of TCV plasmas with negative triangularity in view of DTT operations
Experiments and gyrokinetic simulations of TCV plasmas with negative triangularity in view of DTT operations Open
Negative triangularity (NT) scenarios in TCV have been compared to positive triangularity (PT) scenarios using the same plasma shapes foreseen for divertor tokamak test tokamak operations. The experiments provided a NT/PT L-mode pair and a…
View article: Wave–particle interactions in tokamaks
Wave–particle interactions in tokamaks Open
Transport consequences of the wave–particle interactions in the quasilinear plateau (QP) regime are presented. Eulerian approach is adopted to solve the drift kinetic equation that includes the physics of the nonlinear trapping (NT) and QP…
View article: Tomographic reconstructions of the fast-ion phase space using imaging neutral particle analyser measurements
Tomographic reconstructions of the fast-ion phase space using imaging neutral particle analyser measurements Open
In this paper we demonstrate how the inversion, in energy and major radius (E, R) coordinates, of imaging neutral particle analyser (INPA) measurements can be used to obtain the fast-ion distribution. The INPA is most sensitive to passing …
View article: Measurement of toroidal Alfvén eigenmode-driven fast-ion flows using an imaging neutral particle analyzer at ASDEX Upgrade
Measurement of toroidal Alfvén eigenmode-driven fast-ion flows using an imaging neutral particle analyzer at ASDEX Upgrade Open
Alfvén Eigenmodes-driven fast-ion flows have been measured for the first time at the ASDEX Upgrade tokamak using an imaging neutral particle analyzer. The flow is such that particles are expelled from the mode location, losing energy as th…
View article: NBI optimization on SMART and implications for scenario development
NBI optimization on SMART and implications for scenario development Open
The SMall Aspect Ratio Tokamak (SMART) under commissioning at the University of Seville, Spain, aims to explore confinement properties and possible advantages in confinement for compact/spherical tokamaks operating at negative vs. positive…