Stationary modulation and statistical acceleration of nonrelativistic charged particles in the interplanetary space

On the basis of the last experimental data a joint study of transport and diffusion processes of nonrelativistic charged particles is made in interplanetary turbulent plasma at different distances from the SUn. An analytical solution of the transport equation with regard to diffusion in the momentum space, spatial diffusion, convection and adiabatic deceleration is obtained for the spherically-symmetric case. Energy spectra of protons are presented and a radial gradient of protons with Esub(p)>4 MeV at distances from the Sun r<=1 a.e. is estimated. The calculation results and the experimental measurements obtained at the orbital stations ''Helius 1'' ''Helius-2'' are analyzed. Experimental and theoretical results are in good agreement