A5005158600- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Nonlinear Photonic Systems
- Fluid Dynamics and Turbulent Flows
- Nonlinear Waves and Solitons
- Plasma Diagnostics and Applications
- Dust and Plasma Wave Phenomena
- Fusion materials and technologies
- Advanced Fiber Laser Technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Advanced Mathematical Physics Problems
- Theoretical and Computational Physics
- Quantum chaos and dynamical systems
- Particle accelerators and beam dynamics
- Geomagnetism and Paleomagnetism Studies
- Nonlinear Dynamics and Pattern Formation
- Nuclear reactor physics and engineering
- Fluid Dynamics and Vibration Analysis
- Laser-induced spectroscopy and plasma
- Oceanographic and Atmospheric Processes
- Fractional Differential Equations Solutions
- Ocean Waves and Remote Sensing
- Physics of Superconductivity and Magnetism
Technical University of Denmark
2016-2025
Frederiksberg Hospital
2023
Copenhagen University Hospital
2023
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2021
Space Research Institute
2021
Russian Academy of Sciences
2021
Plasma Technology (United States)
2007-2019
Fusion Academy
2012-2019
Chr. Hansen (Denmark)
2018
European Environment Agency
2013
We investigate the properties of localized waves in cubic nonlinear materials with a symmetric nonlocal response arbitrary shape and degree nonlocality, described by general Schrödinger type equation. prove rigorously bounding Hamiltonian that nonlocality nonlinearity prevents collapse in, e.g., Bose-Einstein condensates optical Kerr media all physical dimensions. The must be have positive definite Fourier spectrum, but can otherwise completely nonlocality. use variational techniques to find...
We present an overview of recent advances in the understanding optical beams nonlinear media with a spatially nonlocal response. discuss impact nonlocality on modulational instability plane waves, collapse finite-size beams, and formation interaction spatial solitons.
We study modulational instability (MI) of plane waves in nonlocal nonlinear Kerr media. For a focusing nonlinearity we show that, although the nonlocality tends to suppress MI, it can never remove completely, irrespective particular profile response function. defocusing stability properties depend sensitively on function profile: for smooth (e.g., Gaussian) are always stable, but MI may occur rectangular response. also find that reduced model weak predicts media arbitrary profiles, as long...
Electron solitary holes were observed in a magnetized collisionless plasma. These identified as Bernstein-Green-Kruskal equilibria, thus being purely kinetic phenomena. The electron hole does not damp even though its velocity is close to the thermal velocity. Two attract each other like particles of negative mass, and coalesce when their relative small.
The modulational instability (MI) of plane waves in nonlocal Kerr media is studied for a general response function. Several generic properties are proven mathematically, with emphasis on how new gain bands formed through bifurcation process when the degree nonlocality, sigma, passes certain values and bandwidth maximum each individual band depends sigma. MI spectrum, including phenomena, then demonstrated exponential rectangular functions. For focusing nonlinearity nonlocality tends to...
We study the formation and interaction of spatial dark optical solitons in materials with a nonlocal nonlinear response. show that unlike local materials, where typically repel, nonlinearity leads to long-range attraction stable bound states solitons.
Fluctuations and particle transport in the scrape-off layer of TCV plasmas have been investigated by probe measurements direct comparison with two-dimensional interchange turbulence simulations at outer midplane. The experiments demonstrate that increasing line-averaged core plasma density, radial density profile scale length becomes broader. flux statistics far exhibit a high degree statistical similarity respect to changes density. onto main chamber wall midplane scales linearly local...
A negative potential barrier on the low-potential side of a moving double layer gives rise to current limitation in collisionless plasma terminated by positively biased cold collector plate $Q$ machine. The is produced front source and moves toward during limitation. When arrives at collector, dissolves increases, causing along whole column. then reforms source.
An electrostatic coherent mode near the electron diamagnetic frequency (20-90 kHz) is observed in steep-gradient pedestal region of long pulse H-mode plasmas Experimental Advanced Superconducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond-coated reciprocating probes. The propagates direction plasma frame with poloidal wavelength ∼8 cm. drives significant outflow particles heat as measured directly probes, thus greatly facilitating sustainment. This shows nature...
The use of low-dimensional dynamical systems as reduced models for plasma dynamics is useful solving an initial value problem requires much less computational resources than fluid simulations. We utilize a data-driven modeling approach to identify model from simulation data convection problem. A with pressure source centered at the inner boundary edge magnetically confined plasma. undergoes sequence bifurcations strength increases. time evolution energies profile, turbulent flow, and zonal...
Two-dimensional fluid simulations of interchange turbulence for geometry and parameters relevant the scrape-off layer magnetized plasmas are presented. The computations, which have distinct plasma production loss regions, reveal bursty ejection particles heat from bulk in form blobs. These structures propagate far into where they dissipated due to transport along open magnetic field lines. From single-point recordings it is shown that blobs asymmetric conditional wave forms lead positively...
Probe measurements of electrostatic plasma fluctuations in the scrape-off layer (SOL) TCV tokamak are compared with results from two-dimensional interchange turbulence simulations. Excellent agreement is found for both radial variation statistical moments and temporal correlations, clearly indicating that turbulent transport SOL due to advection blob-like filamentary structures. This offers an explanation basic mechanism driving anomalous particle now commonly observed broad density...
Two types of solitary structure were investigated experimentally and numerically in a magnetized, plasma-loaded waveguide. One was identified as an ordinary KdV soliton its properties with particular attention to the damping by resonant particles. The other type pulse purely kinetic phenomenon being associated vortex phase space.
The first experimental evidence showing the connection between blob/hole formation and zonal-flow generation was obtained in edge plasma of JET tokamak. Holes as well blobs are observed to be born shear layer, where zonal-flows off meso-scale coherent structures, leading disconnection positive negative pressure perturbations. newly formed transport azimuthal momentum up gradient flow drive while moving outwards. During this process energy is transferred from structures zonal flows via...
A detailed cross-device investigation on the role of filamentary dynamics in high-density regimes has been performed within EUROfusion framework, comparing ASDEX Upgrade (AUG) and TCV tokamaks. Both devices run density ramp experiments at different levels plasma current, keeping toroidal field or q95 constant order to disentangle parallel connection length current. During scan a field, both scrape-off layer (SOL) profiles tend develop clear SOL shoulder lower edge whenever current is...
We study the propagation of intense optical beams in layered Kerr media. With appropriate shapes, with a power close to self-focusing threshold are shown propagate over long distances as quasi-stationary waveguides cubic media supporting periodic nonlinear refractive index.
Numerical fluid simulations of interchange turbulence for geometry and parameters relevant to the boundary region magnetically confined plasmas are shown result in intermittent transport qualitatively similar recent experimental measurements. The two-dimensional simulation domain features a forcing with spatially localized sources particles heat outside which losses due motion along open magnetic-field lines dominate, corresponding edge scrape-off layer, respectively. Turbulent states reveal...
Large-scale radial advection of isolated structures in nonuniformly magnetized plasmas is investigated. The underlying mechanism considered due to the nonlinear evolution interchange motions, without any presumption plasma sheaths. Theoretical arguments supported by numerical simulations reveal an inertial scaling for velocity ideal limit. This increases as square root structure size relative length scale magnetic field. magnitude velocity, well dynamical structures, compares favorably with...
The effect of time-derivative nonlinearity is incorporated into the study modulational instability short pulses propagating through long optical fibers. Conditions for soliton formation are discussed.
A critical review of the literature on similarity solutions nonlinear Schroedinger equations is presented. We demonstrate that self-similar blow-up discovered hitherto are all associated either with a simple stretching invariance, or slightly more complicated conformal invariance and generalizations latter. This generalized "quasi-invariance" reveals nature singularity resolves an old controversy. Most previous work has been done cubic nonlinearity. generalize results to arbitrary power
Low-frequency, flute-type electrostatic fluctuations propagating across a strong, homogeneous magnetic field are studied experimentally. The generated by the Kelvin–Helmholtz instability. presence of relatively long-lived vortexlike structures in background wide-band turbulent is demonstrated conditional sampling technique. Depending on plasma parameters, dominant can appear as monopole or multipole vortices, dipole vortices particular. importance large for diffusion discussed. A statistical...
Viscoelastic vortical fluid motion in a strongly coupled particle system has been observed experimentally. Optical tracking of complex plasma monolayer reveals high grain mobility and large scale vortex flows coexistent with partial preservation the global hexagonal lattice structure. The transport particles is superdiffusive ascribed to Lévy statistics on short time scales memory effects longer influenced by cooperative motion. At these scales, governed covering wide spectrum temporal...
First principles expressions are given for the parameters governing collisional diffusion and parallel losses of mass, momentum energy in tokamak scrape-off layer (SOL) plasmas. These dissipative, or damping, coefficients based on neoclassical perpendicular transport (Pfirsch-Schluter diffusion) classical (sub-sonic advection Spitzer-Harm diffusion). When numerical values derived from these used to compute damping edge-SOL electrostatic (ESEL) turbulence code, simulations correctly reproduce...