Browsing by Author "Engelbrecht, N.E."
Now showing items 1-11 of 11
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An ab initio approach to modelling time-dependent cosmic-ray modulation in the heliosphere
Moloto, K.D. (North-West University (South Africa), 2020)The ab initio approach to cosmic ray modulation places a strong, primary emphasis on understanding the basic causes of cosmic-ray modulation. This requires knowledge and an understanding of both the large and small-scale ... -
An ab initio approach to the historical modulation of cosmic rays
Wolmarans, Carel Pieter (North-West University (South Africa), 2021)The relationship between observed cosmic-ray intensities and the heliospheric magnetic field during the early space age is generally considered to be anomalous, relative to their relationship observed at later times. ... -
An AB initio model for cosmic-ray modulation
Engelbrecht, N.E.; Burger, R.A. (IOP Publishing, 2013)A proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays (CRs) is of vital importance for a better understanding of CR modulation in the heliosphere. This study presents an ab initio ... -
An AB initio model for the modulation of galactic cosmic-ray electrons
Engelbrecht, N.E.; Burger, R.A. (IOP Publishing, 2013)The modulation of galactic cosmic-ray electrons is studied using an ab initio three-dimensional steady state cosmicraymodulation code in which the effects of turbulence on both the diffusion and drift of these cosmic-rays ... -
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, ... -
Cosmic-ray modulation: an ab initio approach
Engelbrecht, N.E.; Burger, R.A. (Springer Verlag, 2014)A better understanding of cosmic-ray modulation in the heliosphere can only be gained through a proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays. We present an ab initio model ... -
Effects of various dissipation range onset models on the 26-day variations of low-energy galactic cosmic-ray electrons
Engelbrecht, N.E.; Burger, R.A. (Elsevier, 2010)The effect of various models presented by Leamon et al. (2000) for the dissipation range cutoff wavenumber on the 26-day variations of galactic cosmic-ray electrons in a Fisk-Parker hybrid field is investigated, by means ... -
A Fisk-Parker hybrid heliospheric magnetic field with a solar-cycle dependence
Burger, R.A.; Krüger, T.P.J.; Hitge, M.; Engelbrecht, N.E. (IOP Publishing, 2008)We present a refinement of the Fisk-Parker hybrid field of Burger and Hitge which now includes a region bordering the solar rotational equator where magnetic field footpoint motion occurs only through diffusive reconnection. ... -
Possible evidence for a Fisk-type heliospheric magnetic field. 1. Analyzing Ulysses/Ket electron observations
Sternal, O.; Engelbrecht, N.E.; Burger, R.A.; Ferreira, S.E.S.; Potgieter, M.S.; Kopp, A. (IOP Publishing, 2011)The propagation of energetic charged particles in the heliospheric magnetic field is one of the fundamental problems in heliophysics. In particular, the structure of the heliospheric magnetic field remains an unsolved ... -
The solar-cycle dependence of the heliospheric diffusion tensor
Nel, Amoré Elsje (North-West University, 2015)Long-term cosmic-ray modulation studies using ab initio numerical modulation models require an understanding of the solar-cycle dependence of the heliospheric diffusion tensor. Such an understanding requires information ... -
Time-dependent cosmic ray modulation
Manuel, R.; Ferreira, S.E.S.; Potgieter, M.S.; Strauss, R.D.; Engelbrecht, N.E. (Elsevier, 2011)Time-dependent cosmic ray modulation is calculated over multiple solar cycles using our well established two-dimensional time-dependent modulation model. Results are compared to Voyager 1, Ulysses and IMP cosmic ray ...