Blar i forfatter "Trulsen, Jan Karsten"

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    • Anomalous transport due to large coherent structures in a magnetized toroidal plasma 

      Fredriksen, Åshild; Pécseli, Hans L; Trulsen, Jan Karsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-18)
      Anomalous transport due to large coherent structures, or coherent events, is studied experimentally in a magnetized toroidal discharge plasma. The present analysis emphasizes anomalous plasma losses as well as transport of electron thermal energy density across magnetic field lines. The experiment was carried out in the Blaamann device at the University of Tromsø. The diagnostics are based on data ...

    • Impulse-driven oscillations of the near-Earth's magnetosphere 

      Sato, Hiroatsu; Pecseli, Hans Laszlo; Trulsen, Jan Karsten; Sandholt, Per Even; Farrugia, Charles J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-09)
      It is argued that a simple model based on magnetic image arguments suffices to give a convincing insight into both the basic static as well as some transient dynamic properties of the near-Earth's magnetosphere, particularly accounting for damped oscillations being excited in response to impulsive perturbations. The parameter variations of the frequency are given. Qualitative results can also be ...

    • Magnetic field-aligned plasma currents in gravitational fields 

      Garcia, Odd Erik; Leer, Egil; Pecseli, Hans; Trulsen, Jan Karsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-03)
      Analytical models are presented for currents along vertical magnetic field lines due to slow bulk electron motion in plasmas subject to a gravitational force. It is demonstrated that a general feature of this problem is a singularity in the plasma pressure force that develops at some finite altitude when a plasma that is initially in static equilibrium is set into slow motion. Classical fluid models ...

    • On the applicability of Taylor's hypothesis, including small sampling velocities 

      Pécseli, Hans L; Trulsen, Jan Karsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-03)
      Taylor's hypothesis, or the frozen turbulence approximation, can be used to estimate also the specific energy dissipation rate ϵ by comparing experimental results with the Kolmogorov–Obukhov expression. The hypothesis assumes that a frequency detected by an instrument moving with a constant large velocity <i><b>V</i></b> can be related to a wavenumber by <i><b>ω=kV</i></b>. It is, however, not obvious ...

    • A solvable model for the basic properties of a simple magnetized plasma torus 

      Fredriksen, Åshild; Pécseli, Hans; Trulsen, Jan Karsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-11)
      A simple magnetized plasma torus is modeled by using a 'top-hat' density variation. The benefit of this simplification is an exactly solvable model, allowing for a few additions, such as an externally maintained parabolic steady state potential variation imposed on the plasma. The combined effects of the resulting plasma rotation and the plasma polarization due to magnetic field gradient particle ...