DI Mag. Dr Bernhard Seiwald

DI Mag. Dr Bernhard Seiwald
Department
Plasma Research Laboratory
Office phone
53684
Email
Office
Oliphant 4 25

Biography

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Information about me may be found on my homepage

And my CV

 

Research interests

Research related information may be found on the Research Section of my homepage and in particular project related information may be found here.

Please find here an incomplete list of my activities and projects.

Fields of activity

  • Computational Physics
  • Plasma and Fusion Physics
  • Nonlinear Dynamics
  • Astronomy and Astrophysics
  • Interests in: Photovoltaics - Solar Cells and Energy System Modeling

Projects

  • Classification of Magnetic Field Lines - in progress

    In toroidal fusion devices a magnetic field line may form either a magnetic flux surface, magnetic islands or a stochastic zone. For various problems (e.g. optimization of stellarators in real space coordinates) it is of interest to classify magnetic field lines according these three groups. The classification should be based purely on the coordinates of the magnetic field line without any further assumptions.

    What shall I say - no funding, so it is leisure activities.

    Keywords: topology, magnetic field line integration

  • Accurate Mapping of Vacuum Magnetic Flux Surfaces and Islands - in progress

    In H-1 experiments a systematic exploration of magnetic islands and flux surfaces is of interest. For this purpose a high resolution electron-beam wire-tomography system is installed. For numerical treatment one needs a extreme accurate model of the experiments magnetic system. Based on the measurements of the electron-beam wire-tomography system the existing numerical models of the magnetic system will be optimized.

    Keywords: optimization, image processing, magnetic field line integration

  • Nearest Point in Complex Magnetic Field Geometry - in progress

    To measure magnetic field fluctuations an array of Mirnov coils is installed in H-1. Data obtained by the Mirnov coils are further analyzed an processed in a magnetic coordinate system, in particular in Boozer coordinates. As the Mirnov coils are located outside the last closed magnetic flux surface (LCMS) and Boozer coordinates exist only for magnetic flux surfaces the position of the Mirnov coils can't be determined in Boozer coordinates. Therefore, one has to find the points on the LCMS which are next neighbours to the corresponding Mirnov coil.

    Keywords: optimization, magnetic coordinates, inversion

  • Stellarator Optimization - in progress

    An energy optimizing method for stellarators is developed and numerically implemented in the code SORSSA. SORSSA is developed for optimizing stellarators with fixed coil design. The figure of merit is the total stored energy in the plasma volume. In the used model, the energy depends on the effective ripple εeff, which is a measure for the neoclassical transport. To optimize the configurations, the currents of the magnetic field coils are varied such that the energy in the plasma is maximized. In addition to the coil currents, it is possible to vary, the coil positions and the angles between the coils. Thus, it is possible to use the code for the design of simple stellarators. The magnetic field is computed directly from the coil currents with help of a Biot-Savart code. Because magnetic field lines are independent of each other in vacuum magnetic fields, the computation of the field lines has been parallelized which significantly increases the speed of the computations. For the optimization process, the Simulated Annealing algorithm is used.

    Currently some upgrades/tasks are ongoing/planned:

    • automatic magnetic axis finder - in progress
    • computation of α-particle confinement properties - not started
    • optimization of H-1 configurations exhibiting stellarator symmetry - in progress
    • optimization of H-1 configurations without stellarator symmetry - not started

    SORSSA has been successfully applied to the following fusion experiments:
    TJ-II (CIEMAT, Spain), U-2M (Kharkov, Ukraine), CNT (Columbia University, New York, USA).

    Keywords: stochastic optimization, neoclassical transport, parallel processing (MPI)

Collaborations

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