Browsing College of Engineering and Science by Author "Qin, Gang"
Now showing items 1-12 of 12
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An effect of perpendicular diffusion on the anisotropy of solar energetic particles from unconnected sources
Qin, Gang; He, H. Q.; Zhang, Ming (2011-08-10)Recently, Tan and coworkers studied the 2001 September 24 solar energetic particle (SEP) event observed by the Wind spacecraft at 1AU and found that there is a counter-streaming particle beam with a deep depression of flux ... -
Effects of perpendicular diffusion on energetic particles accelerated by the interplanetary coronal mass ejection shock
Wang, Y.; Qin, Gang; Zhang, Ming (2012-06-10)In this work, based on a numerical solution of the focused transport equation, we obtained the intensity and anisotropy time profiles of solar energetic particles (SEPs) accelerated by an interplanetary shock in the ... -
Interplanetary transport mechanisms of solar energetic particles
Qin, Gang; Zhang, Ming; Dwyer, Joseph R.; Rassoul, Hamid K. (2004-07-10)Numerical simulations of charged particle trajectories in a Parker field with model turbulence are used to study the transport mechanisms of solar energetic particles (SEPs): magnetic focusing, pitch-angle diffusive transport ... -
The model dependence of solar energetic particle mean free paths under weak scattering
Qin, Gang; Zhang, Ming; Dwyer, Joseph R.; Rassoul, Hamid K.; Mason, Glenn M. (2005-07-01)The mean free path is widely used to measure the level of solar energetic particles' diffusive transport. We model a solar energetic particle event observed by Wind STEP at 0.31-0.62 MeV nucleonˉ¹, by solving the focused ... -
Modulation of galactic cosmic rays during the unusual solar minimum between cycles 23 and 24
Zhao, Lingli; Qin, Gang; Zhang, Ming; Heber, Bernd (2014-03-26)During the recent solar minimum between cycles 23 and 24 (solar minimum P23/24), the intensity of galactic cosmic rays (GCR) measured at the Earth was the highest ever recorded since space age. It is the purpose of this ... -
Nonlinear collisionless perpendicular diffusion of charged particles
Matthaeus, William H.; Qin, Gang; Bieber, John William; Zank, Gary Paul (2003-06-10)A nonlinear theory of the perpendicular diffusion of charged particles is presented, including the influence of parallel scattering and dynamical turbulence. The theory shows encouraging agreement with numerical simulations. -
Nonlinear guiding center theory of perpendicular diffusion: General properties and comparison with observation
Bieber, John William; Matthaeus, William H.; Shalchi, Andreas; Qin, Gang (2004-05-28)A nonlinear guiding center (NLGC) theory for diffusion of charged particles perpendicular to the mean magnetic field was recently proposed. Here, we draw attention to a number of attractive features of this theory: (1) The ... -
Nonlinear parallel and perpendicular diffusion of charged cosmic rays in weak turbulence
Shalchi, Andreas; Bieber, John William; Matthaeus, William H.; Qin, Gang (2004-11-20)The problem of particle transport perpendicular to a magnetic background field is well known in cosmic-ray astrophysics. Whereas it is widely accepted that quasi-linear theory (QLT) of particle transport does not provide ... -
A numerical simulation of solar energetic particle dropouts during impulsive events
Zhang, Ming; Wáng, Yì; Qin, Gang; Dalla, Silvia (2014-06-25)This paper investigates the conditions for producing rapid variations of solar energetic particle (SEP) intensity commonly known as "dropouts." In particular, we use numerical model simulations based on solving the focused ... -
Perpendicular transport of charged particles in composite model turbulence: Recovery of diffusion
Qin, Gang; Matthaeus, William H.; Bieber, John William (2002-10-20)The computation of charged particle orbits in model turbulent magnetic fields is used to investigate the properties of particle transport in the directions perpendicular to the large-scale magnetic field. Recent results ... -
Propagation of solar energetic particles in three-dimensional interplanetary magnetic fields: In view of characteristics of sources
He, H. Q.; Qin, Gang; Zhang, Ming (2011-05-26)In this paper, a model of solar energetic particle (SEP) propagation in the three-dimensional Parker interplanetary magnetic field is calculated numerically. We study the effects of the different aspects of particle sources ... -
Transport of solar energetic particles accelerated by ICME shocks: Reproducing the reservoir phenomenon
Qin, Gang; Wang, Y.; Zhang, Ming; Dalla, Silvia (2013-04-01)In this work, gradual solar energetic particle (SEP) events observed by multiple spacecraft are investigated with model simulations. Based on a numerical solution of the Fokker-Planck focused transport equation including ...