A5091859675- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Laser-induced spectroscopy and plasma
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- Electron and X-Ray Spectroscopy Techniques
- High-pressure geophysics and materials
- Physics of Superconductivity and Magnetism
- Nuclear Physics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Laser Design and Applications
- High-Energy Particle Collisions Research
- Particle Accelerators and Free-Electron Lasers
- European and International Law Studies
- Terahertz technology and applications
- Gyrotron and Vacuum Electronics Research
Chalmers University of Technology
2016-2025
University of Oxford
2025
Kingston College
2025
Culham Science Centre
2024
Culham Centre for Fusion Energy
2024
CEA DAM Île-de-France
2018
Max Planck Society
2013-2017
Max Planck Institute for Plasma Physics
2017
Budapest University of Technology and Economics
2008-2012
Institute for Particle and Nuclear Physics
2008
The SPARC tokamak is a critical next step towards commercial fusion energy. designed as high-field ( $B_0 = 12.2$ T), compact $R_0 1.85$ m, $a 0.57$ m), superconducting, D-T with the goal of producing gain $Q>2$ from magnetically confined plasma for first time. Currently under design, will continue path Alcator series tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in device. achievable conservative...
An overview of the present status research toward final design ITER disruption mitigation system (DMS) is given. The DMS based on massive injection impurities, in order to radiate plasma stored energy and mitigate potentially damaging effects disruptions. this will be extremely challenging due many physics engineering constraints such as limitations port access amount species injected impurities. Additionally, questions relevant remain unsolved mechanisms for mixing assimilation impurities...
Pellets of frozen material traveling into a magnetically confined fusion plasma are accelerated by the so-called pellet rocket effect. The nonuniform heats ablation cloud asymmetrically, producing pressure-driven, rocketlike propulsion pellet. We present semianalytical model this process perturbing spherically symmetric model. Predicted accelerations match experimental estimates in current tokamaks (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"...
In this Letter we investigate factors that influence the effective critical electric field for runaway-electron generation in plasmas. We present numerical solutions of kinetic equation and discuss implications threshold field. show necessary significant formation often is higher than previously calculated due to both (1) extremely strong dependence primary on temperature (2) synchrotron radiation losses. also address context a transition from runaway growth decay. find agreement with recent...
In high-current tokamak devices such as ITER, a runaway avalanche can cause large amplification of seed electron population. We show that disruption mitigation by impurity injection may significantly increase the growth rate in devices. This effect originates from increased number target electrons available for process weakly ionized plasmas, which is only partially compensated friction force on fast electrons. derive an expression plasmas and investigate effects multiplication factor final...
Avoidance of the harmful effects runaway electrons (REs) in plasma-terminating disruptions is pivotal design safety systems for magnetic fusion devices. Here, we describe a computationally efficient numerical tool, that allows self-consistent simulations plasma cooling and associated RE dynamics during disruptions. It solves flux-surface averaged transport equations density, temperature poloidal flux, using bounce-averaged kinetic equation to self-consistently provide electron current, heat,...
Abstract This study systematically explores the parameter space of disruption mitigation through shattered pellet injection in ITER with a focus on runaway electron (RE) dynamics, using modeling tool Dream . The physics fidelity is considerably increased compared to previous studies, by e.g. realistic magnetic geometry, resistive wall configuration, thermal quench onset criteria, as well including additional effects, such ion transport and enhanced RE during quench. work aims provide fairly...
Disruptions in large tokamaks can lead to the generation of a relativistic runaway electron beam that may cause serious damage first wall. To mitigate disruption and suppress application resonant magnetic perturbations has been suggested. In this work we investigate effect on confinement electrons by simulating their drift orbits magnetostatic perturbed fields calculating orbit losses for various initial energies perturbation magnitudes. simulations use TEXTOR-like configuration solve...
We analyze the dynamics of fast electrons in plasmas containing partially ionized impurity atoms, where screening effect bound must be included. derive analytical expressions for deflection and slowing-down frequencies, show that they are increased significantly compared to results obtained with complete screening, already at subrelativistic electron energies. Furthermore, we modifications slowing down frequencies equal importance describing runaway current evolution. Our greatly affect...
Runaway electrons are generated in a magnetized plasma when the parallel electric field exceeds critical value. For such with energies typically reaching tens of MeV, Abraham–Lorentz–Dirac (ALD) radiation force, reaction to synchrotron emission, is significant and can be dominant process limiting electron acceleration. The effect ALD force on runaway dynamics homogeneous investigated using relativistic finite-difference Fokker–Planck codes LUKE (Decker Peysson 2004 Report EUR-CEA-FC-1736,...
SPARC is being designed to operate with a normalized beta of $\beta _N=1.0$ , density $n_G=0.37$ and safety factor $q_{95}\approx 3.4$ providing comfortable margin their respective disruption limits. Further, low poloidal _p=0.19$ at the $q=2$ surface reduces drive for neoclassical tearing modes, which together frozen-in classically stable current profile might allow access robustly tearing-free operating space. Although inherent stability expected reduce frequency disruptions, loading...
An effective disruption mitigation system in a tokamak reactor should limit the exposure of wall to localized heat losses and impact high current runaway electron beams, avoid excessive forces on structure. We evaluate with respect these aspects two-stage deuterium-neon shattered pellet injection an ITER-like plasma, using simulations DREAM framework [M. Hoppe et al (2021) Comp. Phys. Commun. 268, 108098]. To minimize obtained currents optimal range injected deuterium quantities is found....
The generation of an autoresonantly phase-locked high-amplitude plasma waves to the chirped beat frequency two driving lasers is studied in dimensions using particle-in-cell simulations. two-dimensional and laser parameters correspond those that optimized wave amplitude one-dimensional Near start autoresonant locking, simulations appear similar results (Luo et al. , Phys. Rev. Res. vol. 6, 2024, p. 013338) with amplitudes above Rosenbluth–Liu limit. Later, just below breaking, simulation...
Magnetosonic-whistler waves may be destabilized by runaway electrons both in fusion and astrophysical plasmas. A linear instability growth rate of these the presence a avalanche is calculated perturbatively numerical solution full dispersion equation. The local threshold depends on fraction runaways, magnetic field, temperature background plasma. quasilinear analysis shows that main result scattering pitch-angle. It appears possible this could explain why number generated tokamak disruptions...
Disruptions in a large tokamak can cause serious damage to the device and should be avoided or mitigated.Massive gas killer pellet injection are possible ways obtain controlled fast plasma shutdown before natural disruption occurs.In this work, scenarios with different types of impurities studied for an ITER-like plasma.Plasma cooling, runaway generation associated electric field diffusion calculated 1D-code taking Dreicer, hot-tail avalanche processes into account.Thin, radially localised...
Improved understanding of the dynamics runaway electrons can be obtained by measurement and interpretation their synchrotron radiation emission. Models for emitted relativistic are well established, but question how various geometric effects -- such as magnetic field inhomogeneity camera placement influence measurements remains open. In this paper we address issue simulating images spectra using new synthetic diagnostic tool SOFT (Synchrotron-detecting Orbit Following Toolkit). We identify...
The potential formation of multi-mega-ampere beams relativistic "runaway" electrons (REs) during sudden terminations tokamak plasmas poses a significant challenge to the tokamak's development as fusion energy source. Here, we use state-of-the-art modeling disruption magnetohydrodynamics coupled with self-consistent evolution RE generation and transport show that non-axisymmetric in-vessel coil will passively prevent beam disruptions in SPARC tokamak, compact, high-field, high-current device...
Autoresonant phase locking of the plasma wakefield to beat frequency two driving lasers offers advantages over conventional acceleration methods, since it requires less demanding laser parameters and is robust variations in target density. Here, we investigate kinetic nonlinear processes that come into play during autoresonant beat-wave electrons, their impact on field amplitude accelerating structure, efficiency. Particle-in-cell simulations show process depends density a nontrivial way but...
Disruptions in large tokamaks can lead to the generation of a relativistic runaway electron beam that may cause serious damage first wall. To suppress application resonant magnetic perturbations (RMPs) has been suggested. In this work we investigate effect RMPs on confinement electrons by simulating their drift orbits magnetostatic perturbed fields and calculating transport orbit losses for various initial energies different perturbation configurations. simulations model ITER RMP...
This paper investigates the effect of ITER-like wall (ILW) on runaway electron (RE) generation through a comparative study similar slow argon injection JET disruptions, performed with different materials. In carbon case, plateau is observed, while in current quench slower and negligibly small. The aim to shed light reason for these differences by detailed numerical modelling which factors affected RE formation. post-disruption profile calculated one-dimensional model electric field,...
The synchrotron radiation emitted by runaway electrons in a fusion plasma provides information regarding the particle momenta and pitch-angles of electron population through strong dependence spectrum on these parameters. Information about density its spatial distribution, as well time evolution above quantities, can also be deduced. In this paper, we present spectra for typical avalanching distributions. Spectra obtained distribution are compared with emission mono-energetic prescribed...
The current status of the mechanical and electromagnetic design for ICRF antenna system W7-X is presented. Two plugins are discussed: one consisting a pair straps with pre-matching to cover first frequency band, 25–38 MHz, second two short strap triplets band around 76 MHz. This paper focusses on lower band. Power coupling reference plasma profile studied help codes TOPICA Microwave Studio that deliver scattering matrix needed optimization geometric parameters box. Radiation power spectra...
Abstract Improved understanding of runaway-electron formation and decay processes are prime interest for the safe operation large tokamaks, dynamics runaway electrons during dynamical scenarios such as disruptions particular concern. In this paper, we present kinetic modelling with time-dependent plasma parameters; in particular, investigate hot-tail generation a rapid drop temperature. With goal studying self-consistent electric-field evolution, also discuss implementation collision...