Browsing Natural and Agricultural Sciences by Subject "Cosmic rays"

Now showing items 1-10 of 29

    • An ab initio approach to the heliospheric modulation of galactic cosmic rays 

      Minnie, Jaco (North-West University, 2006)
      In the present study we aim to further our understanding of charged particle transport in a magnetized medium. To this end, we perform direct numerical simulations of particle transport in a turbulent magnetic field. From ...

    • Acceleration of cosmic rays in the outer heliosphere 

      Prinsloo, Phillip Lourens (North-West University (South Africa), Potchefstroom Campus, 2016)
      Shortly before the Voyager spacecraft crossed the heliospheric termination shock, they encountered narrow, peak-like enhancements in the intensities of low-energy electrons. These enhancements were associated at the time ...

    • Aspects of the modulation of cosmic rays in the outer heliosphere 

      Ngobeni, Mabedle Donald (North-West University, 2006)
      A time-dependent two-dimensional (2D) modulation model including drifts, the solar wind tennination shock (TS) with diffusive shock acceleration and a heliosheath based on the Parker (1965) transport equation is used to ...

    • Aspects of the time-dependent modulation of galactic cosmic rays throughout a three-dimensional heliosphere 

      Mohlolo, Selwana Timothy (North-West University (South Africa), 2021)
      A dominant feature in the heliosphere is the heliospheric current sheet, separating regions of opposite polarity of the heliospheric magnetic field. This structure is dependent on solar activity through the tilt angle, ...

    • A calibration neutron monitor for long-term cosmic ray modulation studies 

      Krüger, Helena (North-West University, 2006)
      The propagation of high-energy cosmic rays is influenced by the time-varying heliospheric magnetic field embedded in the solar wind, and by the geomagnetic field. To penetrate through this geomagnetic field, they must ...

    • A comparative study of cosmic ray modulation models 

      Raath, Jan Louis (North-West University, 2015)
      Until recently, numerical modulation models for the solar modulation of cosmic rays have been based primarily on finite difference approaches; however, models based on the solution of an appropriate set of stochastic ...

    • Cosmic ray modulation processes in the heliosphere 

      Vos, Etienne Eben (North-West University, 2011)
      The solar minimum of 2009 has been identified as an exceptional event with regard to cosmic ray (CR)modulation, since conditions in the heliosphere have reached unprecedented quiet levels. This unique minimum has been ...

    • Cosmic ray propagation in the galaxy and the heliosphere 

      Bisschoff, Driaan (North-West University, 2018)
      The local interstellar spectra (LIS’s) for cosmic rays (CRs) are still not fully determined over all energy ranges. Numerical modelling, such as with the GALPROP code, can be used to calculate LIS’s for a wide set of CR ...

    • The effect of a Fisk-Parker hybrid magnetic field on cosmic rays in the heliosphere 

      Krüger, Tjaart Petrus Jakobus (North-West University, 2005)
      The existence of a Fisk-type heliospheric magnetic field (HMF) is one of the most debated questions in cosmic-ray modulation. Recently, Burger and Hitge [2004] developed a divergence-free Fisk-Parker hybrid magnetic field ...

    • The effect of the heliospheric current sheet on cosmic-ray modulation 

      Moloto, Katlego Daniel (North-West University (South Africa), Potchefstroom Campus, 2015)
      The heliospheric current sheet is a dominant feature of the heliosphere. As solar activity increases, the tilt angle of the current sheet increases, and so does the region swept out by this structure, to cover most of ...