DI Mag. Dr Bernhard Seiwald
Department  Department of Electronic Materials Engineering 

Office phone  (02) 612 53684 
Office  Off Campus PRL 
Biography
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 H1 experiments a systematic exploration of magnetic islands and flux surfaces is of interest. For this purpose a high resolution electronbeam wiretomography system is installed. For numerical treatment one needs a extreme accurate model of the experiments magnetic system. Based on the measurements of the electronbeam wiretomography 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 H1. 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 ε_{eff}, 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 BiotSavart 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 αparticle confinement properties  not started
 optimization of H1 configurations exhibiting stellarator symmetry  in progress
 optimization of H1 configurations without stellarator symmetry  not started
SORSSA has been successfully applied to the following fusion experiments:
TJII (CIEMAT, Spain), U2M (Kharkov, Ukraine), CNT (Columbia University, New York, USA).Keywords: stochastic optimization, neoclassical transport, parallel processing (MPI)
Collaborations
 MaxPlanckInstitut für Plasmaphysik, Greifswald (Germany)
 Laboratorio Nacional de Fusión, CIEMAT, Madrid
 Columbia Nonneutral Torus CNT at the Department of Applied Physics and Applied Mathematics at the Columbia University, New York (USA)
 Institute of Plasma Physics, National Science Center Kharkov Institute of Physics and Technology (Ukraine)
 Institut für Theoretische Physik  Computational Physics, TU Graz (Austria): Plasma Physics Division
 Institut für Astronomie der KarlFranzensUniversität, Graz (Austria)
Updated: 27 July 2021/ Responsible Officer: Director, RSPhys/ Page Contact: Physics Webmaster