Publication Date:
1985-01-01
Description:
It is well recognized that the pitch angle diffusion coefficients of cosmic rays with large pitch angle in random magnetic fields in interplanetary space will be understood by nonlinear theory. For a decade, several nonlinear theories (Volk, 1973; Jones et al., 1973; Owens, 1974; Goldstein, 1976, 1977) have been proposed to predict the pitch angle diffusion coefficient through 90° pitch angle. However, no consistency has been obtained among them. On this situation, several studies by computer simulations (Kaiser et al., 1978; Moussas et al., 1978; Sakai and Kato, 1984) have been carried out to check the pitch angle scattering coefficients obtained by the above theories. In those computations, the simulated interplanetary magnetic field fluctuations are necessary to calculate the trajectories of charged particles. Kaiser et al (1978) generated magnetic field fluctuations by supposing simply a Markov process. The power spectrum obtained from the simulated fluctuations shows k-2 dependence for a higher value of k, where k is a wavenumber. However, the observed power spectra in the interplanetary space so far show k-1.5 rather than k-2 dependence (Hedgecock, 1975). Also, Sari and Ness (1969) shows k-2~k-1.7 dependence in some period of observations. Hence, in order to obtain the scattering coefficients of cosmic rays in the random magnetic fields in the interplanetary space, it is desirable to be able to yield random magnetic fields corresponding to any type of power spectrum having arbitrary values of spectral index. © 1985, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.
Print ISSN:
0022-1392
Topics:
Geosciences
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