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The 1990 May 24 Solar Cosmic-Ray Event
Vainio, R.; Torsti, J.; Anttila, A. +2 more
This paper presents an integrated analysis of GOES 6, 7 and neutron monitor observations of solar cosmic-ray event following the 1990 May 24 solar flare. We have used a model which includes particle injection at the Sun and at the interplanetary shock front and particle propagation through the interplanetary medium. The model does not attempt to s…
A Joint Analysis of High-Energy Neutrons and Neutron-Decay Protons from a Flare
Vainio, R.; Torsti, J.; Usoskin, I. G. +2 more
A joint analysis of neutron monitor and GOES data is performed to study the production of high-energy neutrons at the Sun. The main objects of the research are the spectrum of >50 MeV neutrons and a possible spectrum of primary (interacting) protons which produced those neutrons during the major 1990 May 24 solar flare. Different possible scena…
Stochastic Wave Growth, Power Balance, and Beam Evolution in Type III Solar Radio Sources
Robinson, P. A.
Energy-balance arguments are combined with the stochastic-growth theory of type III radio sources to determine the properties of the source in average dynamical equilibrium with the beam, and the beam's long-term evolution. Purely linear stochastic-growth theory has previously emphasized that the beam evolves to a state close to marginal stability…
A 2D Numerical Study of Explosive Events in the Solar Atmosphere
Inhester, B.; Innes, D.; Jin, S. -P.
Two-dimensional (2D) compressible magnetohydrodynamic simulations are performed to explore the idea that the asymmetric reconnection between newly emerging intranetwork magnetic field flux and pre-existing network flux causes the explosive events in the solar atmosphere. The dependence of the reconnection rate as a function of time on the density …
Theoretical Plasma Distributions Consistent with ULYSSES Magnetic Field Observations in a Solar Wind Tangential Discontinuity
Tsurutani, B. T.; Roth, M.; De Keyser, J. +3 more
The overall multi-layer structure of the magnetic field profile observed by Ulysses across a broad solar wind tangential discontinuity can be reproduced fairly well by means of a kinetic model. Such a simulation provides complementary information about the velocity distribution functions, which are not always available from the plasma experiment d…
Propagation of Solar Cosmic Rays: Diffusion versus Focused Diffusion
Vainio, R.; Torsti, J.; Kocharov, L. G. +1 more
This paper is designed to bring to the attention the fact that the effect of focusing of solar energetic particles is always essential as compared with scattering, no matter how small the value of the mean free path may be. That is why, an ordinary (`focusing-free') diffusion approach can not be applied to the solar cosmic ray transport. In the ca…
A `Ulysses' Cosmic-Ray Latitude Gradient Observation and Modulation Models
Keppler, E.; Quenby, J. J.; Drolias, B. +2 more
The `EPAC' instrument on Ulysses is sensitive to relativistic cosmic rays when far from Jupiter and in the absence of energetic solar particles. Measurement of the latitude gradient of these particles, after correction for time variations, has been made for the 1993-1994 south polar pass. The average magnitude of the gradient is about the same or …
Calculating the Plasma Deformation Tensor and Kinetic Vorticity from Magnetic Field Time Series: Applications to the Solar Wind
Moussas, X.; Polygiannakis, J. M.
It is shown that the magnetic induction equation reduces to an autoregressive model equation. Assuming weakly ergodic field variations in steady mean plasma flow, this model permits the estimation of the mean flow deformation tensor, velocity divergence and kinetic vorticity from magnetic field time series. Applications, made to hourly-averaged, i…