G. Birkenmeier
A5029025934- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Nuclear Physics and Applications
- Dust and Plasma Wave Phenomena
- Metallurgical Processes and Thermodynamics
- Magnetic Properties and Applications
- Geophysics and Gravity Measurements
- Laser-induced spectroscopy and plasma
- Spacecraft and Cryogenic Technologies
- Magnetic Field Sensors Techniques
- High-Energy Particle Collisions Research
- Laser Design and Applications
- Remote Sensing and Land Use
- Radiation Effects in Electronics
- Nuclear Materials and Properties
- Non-Destructive Testing Techniques
- Astro and Planetary Science
Technical University of Munich
2016-2025
Max Planck Institute for Plasma Physics
2016-2025
Culham Science Centre
2021-2024
Culham Centre for Fusion Energy
2024
Max Planck Society
2012-2021
CEA Cadarache
2018
Institute for Particle and Nuclear Physics
2016
HUN-REN Wigner Research Centre for Physics
2016
Dutch Institute for Fundamental Energy Research
2014
University of California, San Diego
2014
Abstract In 2021 JET exploited its unique capabilities to operate with T and D–T fuel an ITER-like Be/W wall (JET-ILW). This second major campaign (DTE2), after DTE1 in 1997, represented the culmination of a series enhancements—new fusion diagnostics, new injection capabilities, refurbishment plant, increased auxiliary heating, in-vessel calibration 14 MeV neutron yield monitors—as well as significant advances plasma theory modelling community. DTE2 was complemented by sequence isotope...
Abstract The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is high-confinement mode. In this regime, however, periodic relaxations of plasma edge can occur. These edge-localized modes pose a threat to integrity fusion device. Here we reveal strong impact energetic ions on spatio-temporal structure in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between fast at electromagnetic...
A multidiagnostic approach, utilizing Langmuir probes in the midplane, X-point and divertor walls, along with lithium beam infrared measurements is employed to evaluate evolution of scrape-off layer (SOL) ASDEX Upgrade across L-mode density transition leading formation a shoulder. The flattening SOL profiles linked regime change filaments, which become faster larger, similar q∥ profile. This related beginning outer detachment leads onset velocity shear SOL. Experimental are good agreement...
In a wide variety of natural and laboratory magnetized plasmas, filaments appear as result interchange instability. These convective structures substantially enhance transport in the direction perpendicular to magnetic field. According filament models, their propagation may follow different regimes depending on parallel closure charge conservation. This is paramount importance fusion high collisionality scrape-off layer trigger regime transition leading strongly enhanced particle fluxes....
Abstract For the past several years, JET scientific programme (Pamela et al 2007 Fusion Eng. Des . 82 590) has been engaged in a multi-campaign effort, including experiments D, H and T, leading up to 2020 first with 50%/50% D–T mixtures since 1997 ever plasmas ITER mix of plasma-facing component materials. this purpose, concerted physics technology was launched view prepare campaign (DTE2). This paper addresses key elements developed by directly contributing preparation. intense preparation...
The lithium beam emission spectroscopy (Li-BES) is a powerful diagnostic to resolve the plasma edge density with high temporal and spatial resolution.The recent upgrades of Li-BES at ASDEX Upgrade resulting gain in photon flux allow be determined an advanced level accuracy.Furthermore, electron fluctuations are measured using Li-BES.The capabilities limitations measure profiles as well presented.Li-BES suited characterize turbulence scrape off layer (SOL) decreasing sensitivity towards...
A summary of recent results on filamentary transport, mostly obtained with the ASDEX-Upgrade tokamak (AUG), is presented and discussed in an attempt to produce a coherent picture scrape-off layer (SOL) transport. clear correlation found between L-mode density shoulder formation outer midplane transition sheath-limited inertial regimes. Divertor collisionality be parameter triggering transition. reduction ion temperature takes place far SOL after transition, both for background filaments....
In order to understand the mechanisms that determine structure of high confinement mode (H-mode) pedestal, evolution plasma edge electron density and temperature profiles between localised modes (ELMs) is investigated. The onset radial magnetic fluctuations with frequencies above 200 kHz found correlate stagnation pedestal gradient. During presence these gradients are clamped stable against ELM onset. detected fluctuation frequency analysed for a variety discharges different pressure...
Density fluctuations in I-mode discharges ASDEX Upgrade are studied.The specific weakly coherent mode (WCM) appears at the transition from L to I-mode.The WCM but also turbulence general strongly modulated by a low frequency which can be related geodesic acoustic (GAM).The GAM induces an energy transfer away central frequency, indicating underlying instability responsible for WCM.During magnetic close intensified, assigned Alfvénic oscillation.The oscillation is present already L-mode, does...
Blob properties are studied in the scrape-off layer of tokamak ASDEX Upgrade with a fast camera. The gas-puff imaging technique is used to investigate detection rate as well blob size and velocity scaling. experiments were performed L- H-mode phases same discharges study change after L-H transition. In both regimes order few thousand blobs per second, which compatible picture generation by edge micro instabilities. increases H-mode, while radial decreases slightly. changes are, however, not...
The formation of plasma blobs is studied by analyzing their trajectories in a gyrofluid simulation the vicinity separatrix. Most arise at maximum radial electric field outside In general, blob generation not bound to one particular position or instability. A simple model turbulence spreading for scrape-off layer derived. simulations show that dynamics can be represented spreading, which constitutes substantial energy drive far and more suitable quantity study compared skewness.
A stationary H-mode without edge localized modes (ELMs) has been recently achieved in the ASDEX Upgrade tokamak by applying central electron cyclotron resonance heating above L-H power threshold with adequate fueling. It is naturally obtained favorable ∇B configuration and several features which are desirable for future reactors, such as dominant heating, low input torque, possibility of access at power, good energy confinement (), high density no impurity accumulation despite absence ELMs....
In this work we carry out quantitative measurements of particle and heat transport associated to SOL filaments in a tokamak, relate density shoulder formation the advection energy far SOL. For first time, attempt includes direct ion electron temperatures for background filaments. With aim, combine data from number equivalent L-mode discharges ASDEX Upgrade tokamak which different probe heads were installed on midplane manipulator. This approach is validated by comparison with independent...
The relation between the macroscopic input power required at ASDEX Upgrade to access H-mode P thr and microscopic E×B shear has been investigated via fast charge-exchange recombination spectroscopy (CXRS) measurements various toroidal magnetic fields, different electron densities, in both hydrogen deuterium plasmas.For onset, a threshold v minimum, an approximation of shear, found.This identifies not E r as important player for L-H transition.A database including CXRS, Doppler reflectometry...
Abstract We present an overview of results from a series L–H transition experiments undertaken at JET since the installation ITER-like-wall (JET-ILW), with beryllium wall tiles and tungsten divertor. Tritium, helium deuterium plasmas have been investigated. Initial in tritium show ohmic transitions low density power threshold for ( P LH ) is lower than ones densities, while we still lack contrasted data to provide scaling high densities. In there notable shift which minimum <?CDATA...
Abstract The recent deuterium–tritium campaign in JET-ILW (DTE2) has provided a unique opportunity to study the isotope dependence of L-H power threshold an ITER-like wall environment (Be and W divertor). Here we present results from dedicated transition experiments at JET-ILW, documenting tritium plasmas, comparing them with matching deuterium hydrogen datasets. From earlier it is known that as plasma isotopic composition changes deuterium, through varying deuterium/hydrogen concentrations,...
Abstract We study localized edge turbulence in the ASDEX Upgrade tokamak that appears if resonant magnetic perturbations (RMP) are applied to suppress modes (ELMs) high confinement mode. The concomitant density fluctuations detected by microwave reflectometry at outboard midplane. Two can be distinguished, (a) a broadband fluctuation below threshold of RMP field amplitude, and (b) narrow-band quasi-coherent mode (QCM) above threshold. is toroidally spread out but disappears toroidal position...
Abstract Experiments on ASDEX Upgrade (AUG) in 2021 and 2022 have addressed a number of critical issues for ITER EU DEMO. A major objective the AUG programme is to shed light underlying physics confinement, stability, plasma exhaust order allow reliable extrapolation results obtained present day machines these reactor-grade devices. Concerning pedestal physics, mitigation edge localised modes (ELMs) using resonant magnetic perturbations (RMPs) was found be consistent with reduction linear...
Abstract A set of dedicated H-mode discharges with constant heating power combining Neutral Beam Injection and Electron Cyclotron Resonance Heating have been executed at the ASDEX Upgrade tokamak using a high triangularity magnetic geometry in order to investigate impact filamentary transport divertor non-divertor components. The evolution upstream scrape-off layer (SOL) profiles correlated separatrix quantities, mostly turbulence control parameter <mml:math...
The Alfvén instability nonlinearly excited the energetic-particle-driven geodesic acoustic mode on ASDEX-Upgrade tokamak, as demonstrated experimentally. mechanism of excitation and nonlinear evolution is not yet fully understood. In present work, a first-principles simulation using MEGA code investigated properties in both linear growth saturated phases. Here we show that successfully reproduced coexistence these two modes, agreed with experimental results well. Conclusive evidence showed...
Abstract On the basis of several recent breakthroughs in fusion research, many activities have been launched around world to develop power plants on fastest possible time scale. In this context, high-fidelity simulations plasma behavior large supercomputers provide one main pathways accelerating progress by guiding crucial design decisions. When it comes determining energy confinement a magnetic device, which is key quantity interest, gyrokinetic turbulence are considered approach choice –...
The dynamics of filaments or blobs in the scrape-off layer magnetic fusion devices are studied by magnitude estimates a comprehensive drift-interchange-Alfvén fluid model. standard blob models reproduced cold ion case. Even though usually neglected, layer, temperature can exceed electron an order magnitude. pressure affects amongst others adding up to interchange drive and polarisation current. It is shown how both effects modify scaling laws for filament velocity dependence its size....
Abstract Limit-cycle oscillations (LCOs) close to the power threshold of L- H-mode transitions are investigated in plasmas ASDEX Upgrade. During this phase, referred as I-phase, a strong magnetic activity poloidal field <?CDATA ${{\overset{\centerdot}{{B}}\,}_{\theta}}$ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mi>B</mml:mi> <mml:mo>⋅</mml:mo> </mml:mover> </mml:mstyle>...
Abstract The spatio-temporal interplay between turbulence, mean and zonal flows has been investigated at the L–H H–L transitions in edge region of ASDEX Upgrade tokamak. Close to both transitions, an intermediate phase (I-phase) characterized by ‘limit cycle like oscillations’ (LCOs) is observed which periodic bursts turbulence correlate with <?CDATA $\mathbf{E}\times \mathbf{B}$ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false">...