Improved Representation of Heliospheric Magnetic Field Fluctuations in Ab Initio Models of Cosmic Ray Modulation

We construct a theory of solar modulation of cosmic rays using a diffusion tensor based upon ab initio turbulence and scattering theories, employing direct numerical simulations of the steady state cosmic ray transport equation to examine important factors that affect modulation. In most numerical simulations the magnetic field fluctuations, a crucial element in scattering theory, are calculated from very simple theories. Moreover, it is hard to determine these quantities everywhere in the heliosphere from these simple theories and hence these quantities are usually extraploated within 1 AU. An improved procedure would be to numerically solve the governing equations for Elsasser variables in the entire heliosphere taking into account large scale variations of density, solar wind speed etc in the inner and outer heliosphere. Added to it, the fluctuations depend on the abundance and properties of pickup ions and cross helicity of magnetic field. Hence we have taken up the task of finding the fluctuations in every point of our heliospheric domain which extends to almost 100 AU by directly integrating the equations for fluctuations in terms of Elsasser variables . More importantly, we intend to distinguish the inward and outward travelling sense of velocity-magnetic field correlation which has not been taken up in earlier modulation work. Our plan is to use the computed distribution of fluctuations in our ab initio modulation theory.