The passage of energetic charged particles through interplanetary space

Parker, E. N.

doi:10.1016/0032-0633(65)90131-5

Cited by 1,476 publications

(995 citation statements)

References 25 publications

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“…A similar structure was also found for collisional diffusion coefficients in a plasma in thermal equilibrium [19]. Furthermore, regarding τ as the scattering time, these expressions can also be obtained by treating the magnetic disturbances as hard-sphere scattering centers [20], and is known as the "classical scattering result" [21,22,23].…”

Section: Calculation Of Transverse and Hall Diffusion Coefficientssupporting

confidence: 54%

Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum

Candia¹,

Roulet²,

Epele³

2002

J. High Energy Phys.

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We reconsider the scenario in which the knee in the cosmic ray spectrum is explained as due to a change in the escape mechanism of cosmic rays from the galaxy from one dominated by transverse diffusion to one dominated by drifts. We solve the diffusion equations adopting realistic galactic field models and using diffusion coefficients appropriate for strong turbulence (with a Kolmogorov spectrum of fluctuations) and consistent with the assumed magnetic fields. We show that properly taking into account these effects leads to a natural explanation of the knee in the spectrum, and a transition towards a heavier composition above the knee is predicted.

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Section: Calculation Of Transverse and Hall Diffusion Coefficientssupporting

confidence: 54%

Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum

Candia¹,

Roulet²,

Epele³

2002

J. High Energy Phys.

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“…Their model assumes that the diffusion coefficient (k) is a separable function of radial distance (r) and GCR rigidity (R). The model retains much of the physics of Parker's [1965] equation (diffusion, convection, and adiabatic energy loss), only drifts are left out. It may be argued that drift contributions [Parker, 1963] are small, since the low GCR density region inside an ICME survives far into the heliosphere.…”

Section: Discussionmentioning

confidence: 99%

Cosmic ray detector response to transient solar modulation: Forbush decreases

Ahluwalia

Fikani

2007

J. Geophys. Res.

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[1] The observed modulation of galactic cosmic ray (GCR) intensity, on time and spatial scales, contains information regarding their transport in the heliosphere. One way to extract crucial information from the data is to study the rigidity dependence of modulation. A methodology is described to study the rigidity dependence of the short-term variations in galactic cosmic ray intensity Earth, in terms of the median rigidity of detector response (R m ) to cosmic ray spectrum. We define R m as the rigidity below which lies 50% of detector counting rate. For neutron monitors (NMs), it is easily calculated from the latitude survey obtained at sea level and higher elevations. We compute R m values for some NM sites; solar cycle dependence for them is shown to be small. Their practical utility is demonstrated in a study of transient cosmic ray solar modulation (Forbush decreases (FDs)), using data published in the literature. We plot the rigidity dependence of the amplitudes of three large Forbush decreases that occurred during the declining phase of three solar cycles (19, 20, and 21). We show that the Forbush decrease amplitude varies inversely with R m over a large range (1 to 300 GV) of GCR rigidities. Thereby, we rule out the existence of a ''transition rigidity'' suggested by Jokipii even for a short-term modulation (large Forbush decreases). We speculate that the force field model may be applicable to large Forbush decreases.

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“…in the interplanetary medium can be described in terms of a sphericallysymmetric Fokker-Planck equation (Parker, 1965;Gleeson and Axford, 1967):…”

Section: Modulation Equations and The Distribution Functionmentioning

confidence: 99%

“…As can be seen from the second term in (1) or (13), taking V constant, this is just the rate of change in kinetic energy due to the expansion of the solar wind (Parker, 1965).…”

Section: Low Energiesmentioning

confidence: 99%

Solar modulation of galactic cosmic rays: 3. Implications of the Compton-Getting Coefficient

Fisk

Forman²,

Axford

1973

J. Geophys. Res.

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It is useful to express spectra of modulated galactic cosmic rays in terms of the Compton‐Getting coefficient C. This parameter can reveal the energy range over which the force field approximation is valid and the range where convection effects dominate over those of diffusion. A value of C near zero over an extended low‐energy range (according to recent observations this is the situation for protons) implies that the radial gradient at low energies cannot be large. This small gradient may imply, in turn, that the diffusion coefficient increases beyond 1 AU less rapidly than if it were proportional to heliocentric radial distance and/or that there is essentially no scattering for a sizeable distance from the sun to earth. The behavior of C with rigidity (or energy) is discussed in terms of the omnidirectional distribution function ƒ0. Contours of constant ƒ0 in the heliocentric distance versus rigidity plane are useful for illustrating the mean rigidity loss experienced by cosmic rays in the interplanetary medium.

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The passage of energetic charged particles through interplanetary space

Cited by 1,476 publications

References 25 publications

Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum

Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum

Cosmic ray detector response to transient solar modulation: Forbush decreases

Solar modulation of galactic cosmic rays: 3. Implications of the Compton-Getting Coefficient

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