Explanipedia

Experimental characterization of the edge fluctuations during I-phase at ASDEX Upgrade Open

J. Kalis, G. Birkenmeier, M. Griener, G. Grenfell, E. Wolfrum , et al. · 2025

The intermediate phase (I-phase) is a plasma regime that exists at the transition from the low-confinement mode (L-mode) to the fully developed high-confinement mode (H-mode), or vice versa. This regime is characterized by improved particl…

Two-dimensional dynamics of divertor detachment at ASDEX Upgrade Open

S. Hörmann, M. Cavedon, M. Griener, D. Wendler, D. Brida , et al. · 2025

A newly installed thermal helium beam diagnostic in the outer divertor of ASDEX Upgrade (Hörmann et al 2024 Rev. Sci. Instrum. 95 113507) was used for the first time to analyse two-dimensional (2D) electron temperature, density and pressur…

Progress in pedestal and edge physics: Chapter 3 of the special issue: on the path to tokamak burning plasma operation Open

M.E. Fenstermacher, L. R. Baylor, E. de la Luna, M. Dunne, G.T.A. Huijsmans , et al. · 2025

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 …

Impact of shape and global <i>β</i> on ASDEX Upgrade pedestal structure Open

L. Radovanovic, E. Wolfrum, M. Dunne, G. Harrer, F. Aumayr · 2025

The stability and confinement of the pedestal, the outermost region of the confined plasma in a tokamak, are crucial for its efficient operation and performance. This work describes ASDEX Upgrade experiments designed to analyse the pedesta…

Bayesian inference of radial impurity transport in the pedestal of ASDEX Upgrade discharges using charge-exchange spectroscopy Open

Tabea Gleiter, R. Dux, F. Sciortino, T. Odstrčil, Daniel Fajardo , et al. · 2025

We present a novel framework for quantifying radial impurity transport in the pedestal of ASDEX Upgrade (AUG) discharges. Our method is based on charge-exchange recombination spectroscopy measurements of line radiation from multiple impuri…

The quasi-continuous exhaust regime in ASDEX Upgrade and JET Open

M. Faitsch, Michael P. Dunne, E. Lerche, P. Lomas, I. Balboa , et al. · 2025

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…

Transport and confinement physics: Chapter 2 of the special issue: on the path to tokamak burning plasma operation Open

M. Yoshida, R. M. McDermott, C. Angioni, Y. Camenen, J. Citrin , et al. · 2025

Progress in physics understanding and theoretical model development of plasma transport and confinement (TC) in the ITPA TC Topical Group since the publication of the ITER Physics Basis (IPB) document (Doyle et al 2007 Nucl. Fusion 47 S18)…

EDA H-mode in ASDEX Upgrade: scans of heating power, fueling, and plasma current Open

L. Gil, T. Pütterich, C. Silva, D. Hachmeister, G. D. Conway , et al. · 2025

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…

Model for the X-point radiator height and its energetic coupling to the plasma edge Open

U. Stroth, M. Bernert, T. Lunt, O. Pan, E. Wolfrum · 2025

The physics governing the height of the X-point radiator (XPR) and the influence of the related radiation losses on the edge temperature profiles is studied with a reduced power balance model, which is an extension of a model developed to …

Quasi-continuous exhaust operational space Open

M. Dunne, M. Faitsch, L. Radovanovic, E. Wolfrum · 2024

The IPED predictive pedestal code has been used to determine the critical gradients for the onset of 1) separatrix ballooning modes and 2) global peeling-ballooning modes as a function of plasma shaping. This results in a scaling of the on…

Effect of local wall clearance on scrape-off layer electron density profiles in ASDEX Upgrade Open

B. Tál, E. Wolfrum, M. Bernert, G. Birkenmeier, D. Brida , et al. · 2024

The plasma electron density is measured with multiple diagnostics in the scrape-off layer of the ASDEX Upgrade tokamak. The recorded values are typically in good agreement in the case of exponentially decaying profiles at low densities, bu…

Characterization of highly radiating nitrogen-seeded H-mode plasmas in unfavorable B<sub>T</sub> at ASDEX Upgrade Open

L. Chen, E. Wolfrum, O. Pan, B. Kurzan, M. Bernert , et al. · 2024

The highly radiating nitrogen-seeded H-mode plasmas in unfavorable B T has been characterized in the ASDEX Upgrade tokamak (AUG). Three levels of nitrogen puffing rates have been injected into a fully detached H-mode plasma, which is run i…

The multi-faced nature of the quasicoherent mode in EDA H-mode Open

G. Grenfell, L. Gil, P. Mänz, C. Silva, Jiřı́ Adámek , et al. · 2024

In order to extend the enhanced D-Alpha H-mode to future devices, it is crucial to understand the properties of the main signature of this regime, the quasicoherent mode (QCM), that likely clamps the pressure gradient below the ideal magne…

Non-linear MHD investigations of high-confinement regimes without type-I ELMs in ASDEX Upgrade and JT-60SA Open

A. Cathey, M. Hoelzl, L. Meier, M. Dunne, G. T. A. Huijsmans , et al. · 2024

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…

Influence of the magnetic configuration on the high-field side scrape-off layer at ASDEX Upgrade and the role of the secondary separatrix Open

D. Hachmeister, C. Silva, J. Santos, G. D. Conway, L. Gil , et al. · 2024

In tokamaks, radial transport is ballooning, meaning it is enhanced at the low-field side (LFS). This work investigates the effect of the magnetic configuration on the high-field side (HFS) scrape-off layer. Our experiments involved L-mode…

The radial localization of the transition from low to high confinement mode in the ASDEX Upgrade tokamak Open

M. Cavedon, T. Happel, P. Hennequin, R. Dux, K. Höfler , et al. · 2024

A novel experimental method is applied to localize the initial suppression of turbulence, in the form of density fluctuations, at the transition from the low (L-) to the high (H-) confinement mode in toroidal magnetic fusion plasmas. The h…

Complex structure of turbulence across the ASDEX Upgrade pedestal Open

L. Leppin, T. Görler, M. Cavedon, M. Dunne, E. Wolfrum , et al. · 2023

The theoretical investigation of relevant turbulent transport mechanisms in H-mode pedestals is a great scientific and numerical challenge. In this study, we address this challenge by global, nonlinear gyrokinetic simulations of a full ped…

Structure of the electron temperature profile around the separatrix Open

S Díaz Esteban, M. Griener, E. Wolfrum, R. Fischer, D. Wendler , et al. · 2023

The temperature decay length ( ) in the near scrape-off layer (SOL) reflects the ratio between the transport parallel to the magnetic field lines via Spitzer–Härm electron conduction and the perpendicular mechanisms involving neoc…

Experimental characterization of the quasi-coherent mode in EDA H-Mode and QCE scenarios at ASDEX Upgrade Open

J. Kalis, G. Birkenmeier, P. Mänz, T. Eich, M. Griener , et al. · 2023

The quasi-coherent mode (QCM), appearing in enhanced D high confinement mode (EDA H-mode) and quasi-continuous exhaust (QCE) plasmas has been analysed in detail at ASDEX Upgrade via thermal helium beam spectroscopy under various discha…

Two-dimensional reconstruction of filament temperatures and densities with the thermal helium beam at ASDEX Upgrade Open

D. Wendler, G. Birkenmeier, M. Griener, R. Dux, R. Fischer , et al. · 2023

In the scrape-off layer (SOL) of fusion plasmas, radial particle and energy transport is mainly carried by plasma filaments. The plasma parameters of such filaments can be measured by the thermal helium beam diagnostic (THB). By means of a…

Impact of toroidal rotation on the resistive ballooning modes in ASDEX Upgrade tokamak Open

B. Vanovac, J. Puchmayr, R. Bielajew, M. Willensdorfer, E. Wolfrum , et al. · 2023

In this work, we investigate the behavior of instabilities appearing between type-I edge localized modes (ELMs), with increasing neutral beam injection (NBI) power concomitant increase in toroidal rotation, and compare it to the modeling r…

Dynamic edge transport investigations at ASDEX Upgrade using gas puff modulation Open

C. Schuster, E. Wolfrum, T. Görler, E. Fable, R. Fischer , et al. · 2023

Gas puff modulation experiments are performed at ASDEX Upgrade in L-mode, EDA H-mode and quasi-continuous exhaust discharges. Plasma density and temperatures are measured and their temporal development is analyzed simultaneously, revealing…

Analysis and expansion of the quasi-continuous exhaust (QCE) regime in ASDEX Upgrade Open

M. Faitsch, T. Eich, G. Harrer, E. Wolfrum, D. Brida , et al. · 2023

The quasi-continuous exhaust (QCE) regime, formerly known as either type-II ELM or small ELM regime is studied in ASDEX Upgrade. The regime is a natural type-I ELM-free H-mode. The operational space of QCE discharges in ASDEX Upgrade with …

Probing non-linear MHD stability of the EDA H-mode in ASDEX Upgrade Open

A. Cathey, M. Hoelzl, L. Gil, M. Dunne, G. Harrer , et al. · 2023

Regimes of operation in tokamaks that are devoid of large edge localised modes have to be better understood to extrapolate their applicability to reactor-relevant devices. This paper describes non-linear extended magnetohydrodynamic (MHD) …

Electron temperature fluctuation levels of the quasi-coherent mode across the plasma radius Open

B. Vanovac, J. Stöber, E. Wolfrum, M. Willensdorfer, L. Gil , et al. · 2023

EDA H-mode is an ELM-free regime in which the edge quasi-coherent mode (QCM) replaces the ELMs. The estimated location of the quasi-coherent mode is in a partly optically thin region of steep gradients localized between ρ pol = 0.96 -1. Re…

Compensation of plasma fluctuation induced shadowing effects in gas puff imaging data Open

M. Griener, J. Kalis, D. Wendler, G. Birkenmeier, E. Wolfrum , et al. · 2022

For gas puff imaging (GPI) studies of turbulent processes in the plasma edge, it is often assumed that the emitted light is mainly proportional to the local electron density. This, however, only holds for low electron densities in the far …

Quasicontinuous Exhaust Scenario for a Fusion Reactor: The Renaissance of Small Edge Localized Modes Open

G. Harrer, M. Faitsch, L. Radovanovic, E. Wolfrum, Christopher G. Albert , et al. · 2022

Tokamak operational regimes with small edge localized modes (ELMs) could be a solution to the problem of large transient heat loads in fusion reactors. A ballooning mode near the last closed flux surface governed by the pressure gradient a…

Simulations of turbulence and profile evolution across the edge and scrape-off-layer of diverted tokamaks Open

W. Zholobenko, T. Body, A. Stegmeir, M. Griener, G. D. Conway , et al. · 2022

Developing a physics understanding of the quasi-continuous exhaust regime: pedestal profile and ballooning stability analysis Open

L. Radovanovic, M. Dunne, E. Wolfrum, G. Harrer, M. Faitsch , et al. · 2022

It has been experimentally observed that at ASDEX Upgrade (AUG) plasmas at relatively high shaping, an increase of gas fuelling corresponds to an increase of the frequency and intensity of the type-I edge localised modes (ELMs). At high en…

Non-parametric inference of impurity transport coefficients in the ASDEX Upgrade tokamak Open

T. Nishizawa, R. Dux, R. M. McDermott, F. Sciortino, M. Cavedon , et al. · 2022

We present a non-parametric inference of impurity transport coefficients by using charge exchange recombination spectroscopy measurements of Ne X, Ne VIII, O VIII, and C VI lines. Due to their close atomic numbers, neon, oxygen and carbon …

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