A5030604107- Magnetic confinement fusion research
- Laser-Plasma Interactions and Diagnostics
- Ionosphere and magnetosphere dynamics
- Advanced Fiber Laser Technologies
- Dust and Plasma Wave Phenomena
- Solar and Space Plasma Dynamics
- Nonlinear Photonic Systems
- Fluid Dynamics and Turbulent Flows
- Laser-Matter Interactions and Applications
- Nonlinear Waves and Solitons
- Quantum chaos and dynamical systems
- Laser-induced spectroscopy and plasma
- Nonlinear Dynamics and Pattern Formation
- Fusion materials and technologies
- Optical Network Technologies
- Plasma Diagnostics and Applications
- Theoretical and Computational Physics
- Geomagnetism and Paleomagnetism Studies
- Superconducting Materials and Applications
- High-pressure geophysics and materials
- Meteorological Phenomena and Simulations
- Ammonia Synthesis and Nitrogen Reduction
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Mathematical Physics Problems
- Statistical Mechanics and Entropy
Heinrich Heine University Düsseldorf
2014-2024
Max Planck Institute for Plasma Physics - Greifswald
2019-2021
École Polytechnique
2014
University of California, San Diego
2008
Forschungszentrum Jülich
2006-2007
Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute
2002
Advisory Board Company (United States)
1994-1999
Universitätsmedizin Greifswald
1999
Fondazione "Ugo Bordoni"
1997
Internationale Akademie Berlin
1994-1997
A study of three-dimensional (3D) perturbed magnetic field structures and transport for edge localized mode control experiments with resonant perturbations at DIII-D is presented. We focus on ITER-Similar Shape plasmas ITER relevant electron pedestal collisionalities . This performed in comparison results from TEXTOR-Dynamic Ergodic Divertor circular limiter plasmas. For both the structure analyzed vacuum paradigm—superimposing external RMP unperturbed equilibrium. TEXTOR L-mode this...
The magnetic-field perturbation produced by the dynamic ergodic divertor in TEXTOR changes topology of magnetic field plasma edge, creating an open chaotic system. spectrum contains only a few dominant harmonics and therefore it can be described analytical model. modeling is performed vacuum approximation without assuming backreaction does not rely on any experimentally obtained parameters. It shown that this predicts many details observed structure. Several experiments have been to prove...
An analytical approach based on the perturbed discrete Ablowitz-Ladik equation is applied to investigate intrinsic localized modes for two different models of one-dimensional anharmonic lattices, namely, a chain with nonlinear interatomic interaction and on-site potential. It shown that motion strongly affected by an effective periodic (Peierls-Nabarro) potential, but former model moving may still exist in wide region mode parameters, whereas latter one they will be always captured lattice...
In DIII-D the splitting and deformation of separatrix due to externally applied resonant magnetic perturbations is calculated using a vacuum field line integration code (TRIP3D–MAFOT). The resulting footprint pattern on divertor target plates shown in high resolution by contour plots connection lengths penetration depths lines. Substructures inside stripes are discovered. Regions deep penetrating long connecting lines, which related internal resonances their manifolds, alternate with regions...
The decay of a circularly polarized electromagnetic wave propagating parallel to an external magnetic field into another and ion acoustic in homogeneous plasma is considered.
The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating m/n=3/1 mode configuration, are presented. deeply penetrating external magnetic field perturbation this configuration increases toroidal plasma rotation. Staying below excitation threshold for m/n=2/1 tearing mode, rotation is always direction current, even if projection rotating opposite direction. observed consistent with a radial electric field, generated by an enhanced electron transport ergodic layers near...
This paper considers the nonlinear propagation of an intense laser pulse in plasmas. The equation for wave envelope is derived accounting nonlinearities originating from electron-mass variation as well self-interaction field. It shown that and equations governing slow plasma response can be represented terms energy integral a classical particle. analysis potential reveals existence localized solutions. criteria latter to occur are obtained. A small-amplitude limit also discussed.
The decay of a high-frequency wave into scattered and an electrostatic is investigated for homogeneous magnetized plasma. For propagation in arbitrary directions, equation the obtained accounting effect non-linear current density produced by three-wave interaction process. As illustration, electromagnetic waves perpendicular to external magnetic field considered. growth rates thresholds stimulated scattering modulational instabilities are obtained. influence weak inhomogeneity also
Parametric plasma processes received renewed interest in the context of generating ultra-intense and ultra-short laser pulses up to exawatt-zetawatt regime. Both Raman as well Brillouin amplifications seed were proposed. Here, we investigate one-dimensional (1D) backscattering geometry with help numerical simulations. For optimal amplification, scattering is considered so called strong coupling (sc) Special emphasis lies on dependence amplification process finite duration initial pulses....
Asymptotical and mapping methods to study the structure of magnetic field perturbations line dynamics in a tokamak ergodic divertor toroidal geometry are developed. The investigation is applied Dynamic Ergodic Divertor under construction for Torus Experiment Technology Oriented Research (TEXTOR-94) Tokamak at Jülich [Fusion Eng. Design 37, 337 (1997)]. An ideal coil configuration designed create resonant plasma edge considered. In cylindrical geometry, analytical expressions vacuum such...
Parametric excitation of convective cells by drift waves is considered. Noting that the convective-cell fluctuation electrostatic potential much larger than density, we derive a set coupled differential equations describing interaction and cells. For weak pump, general dispersion relation which describes three-wave decay modulational instabilities given. The growth rate latter found to be generally smaller instability. Our analytical result agrees with computer simulation in enhanced appear...
Numerical modeling of the typical footprint structures on target plates a divertor tokamak is presented. In DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] toroidal mode number n=3 resonant magnetic perturbations are responsible for characteristic stripes. The numerics can resolve substructures within each stripe, which related to internal topology. It shown that inner plate be predicted by unstable manifolds separatrix and q=4 surface. By their intersection with form boundary within....
A plasma photonic crystal consists of a density grating which is created in underdense by counterpropagating laser beams. When high-power pulse impinges the crystal, it might be reflected or transmitted. So far only one type polarization, namely so-called s wave (or TE mode) was investigated (when electric field vector perpendicular to plane incidence). Here, when investigating also p waves TM modes, where magnetic incidence), detected that transmission and reflection properties depend on...
Symplectic twist mapping is proposed to model magnetic field line dynamics in the ergodic divertor at tokamak plasma edge. The relationship between a perturbation function and found. specified for Dynamic Ergodic Divertor being Torus Experiment Technology Oriented Research (TEXTOR-94) [Fusion Eng. Design, 37, 337 (1997)]. spectrum of poloidal harmonics assumed be localized around m=12. It creates stochastic layer near resonant surface q=3. applied formation diffusivity For moderate...
Ultrashort laser pulse propagation in a generalized nonconservative system is considered. Slopes appearing the form of third-order time derivative for narrow widths, nonlinear dispersion, and self-frequency shift arising from stimulated Raman scattering are taken into account. An exact analytical solitonlike solution presented femtosecond solitary pulse. The stability latter has been shown numerically by applying perturbations amplitude chirp, as well adding white noise. results indicate...
Drift vortices in plasmas described by the Petviashvili equation case of strong temperature inhomogeneities or Hasegawa–Mima density gradients are investigated. Both equations allow for two-dimensional vortex solutions. The models reviewed and forms discussed. In temperature-gradient case, stationary solutions only known numerically, whereas gradient analytical expressions exist. latter called modons; here ground states result a stability calculation is that both types solutions, as well...
The ergodization of the magnetic field lines imposed by dynamic ergodic diverter (DED) in TEXTOR can lead both to confinement improvement and deterioration. cases substantial are resonant ways related particular conditions which flux tubes starting at $X$ points induced islands connected with wall. This opening process is a characteristic modification heat deposition pattern divertor target plate leads increase steepening core plasma density pressure. tentatively attributed electric...
Ultra-intense and ultra-short laser pulses may be generated up to the exawatt-zetawatt regime due parametric processes in plasmas. The minimization of unwanted plasma leads operational limits which are discussed here with respect filamentation. Transverse filamentation, originally was derived for plane waves, is being investigated seed pulse propagation so called π-pulse limit. A three-dimensional (3D) three-wave-interaction model basis present investigation. To demonstrate applicability...
Laser-driven plasma density gratings in underdense are shown to act as photonic crystals for high power lasers. The created by counterpropagating laser beams that trap electrons, followed ballistic ion motion. This leads strong periodic modulations with a lifetime on the order of picoseconds. grating structure is interpreted crystal time-dependent property, e.g., band gap width. In Maxwell–Vlasov and particle-in-cell simulations it demonstrated may frequency filter mirror ultra-short...
The stability problem for the so-called continuous-discrete solitons in a nonlinear fiber array is examined. We prove that ground states are unstable if first derivative of ``energy'' integral P=${\mathit{tsum}}_{\mathit{n}}$F\ensuremath{\Vert}${\mathrm{\ensuremath{\Psi}}}_{\mathit{n}}$${\mathrm{\ensuremath{\Vert}}}^{2}$dt with respect to soliton parameter ${\ensuremath{\lambda}}^{2}$ negative.
New results from the generation of runaways and loss runaway electrons in an ergodized magnetic field are presented. For process, a clear difference between 'normal' clean, freshly boronized wall condition has been found. Under clean conditions, one observes at low densities not only with energies up to 30 MeV discharges even lower electron density finds more but energy low-MeV regime. The utilized as test particles for revealing line structure. measurements m/n = 6/2 base mode configuration...
Experimental observations of heat fluxes on divertor plates tokamaks show typical structures (boomerang wings) for varying edge safety factors. The flux patterns follow from general principles nonlinear dynamics. pattern selection is due to the unstable and stable manifolds hyperbolic fixed points last intact island chain. Based manifold analysis, experimental can be explained in full detail. Quantitative results are presented terms penetration depths field lines.