TY - JOUR

T1 - The 90° problem of scattering theory revisited

T2 - Dynamical turbulence versus nonlinear effects

AU - Dosch, A.

AU - Kourakis, I.

AU - Shalchi, A.

PY - 2007/12/1

Y1 - 2007/12/1

N2 - The 90° problem of cosmic-ray transport theory is revisited in this paper. By using standard forms of the wave spectrum in the solar wind, the pitch-angle Fokker-Planck coefficient and the parallel mean free path are computed for different resonance functions. A critical comparison is made of the strength of 90° scattering due to plasmawave effects, dynamical turbulence effects and nonlinear effects. It is demonstrated that, only for low-energy cosmic particles, dynamical effects are usually dominant. The novel results presented here are essential for an effective comparison of heliospheric observations for the parallel mean free path with the theoretical model results.

AB - The 90° problem of cosmic-ray transport theory is revisited in this paper. By using standard forms of the wave spectrum in the solar wind, the pitch-angle Fokker-Planck coefficient and the parallel mean free path are computed for different resonance functions. A critical comparison is made of the strength of 90° scattering due to plasmawave effects, dynamical turbulence effects and nonlinear effects. It is demonstrated that, only for low-energy cosmic particles, dynamical effects are usually dominant. The novel results presented here are essential for an effective comparison of heliospheric observations for the parallel mean free path with the theoretical model results.

UR - http://www.scopus.com/inward/record.url?scp=36348974605&partnerID=8YFLogxK

U2 - 10.1088/0954-3899/34/12/006

DO - 10.1088/0954-3899/34/12/006

M3 - Article

AN - SCOPUS:36348974605

SN - 0954-3899

VL - 34

SP - 2595

EP - 2610

JO - Journal of Physics G: Nuclear and Particle Physics

JF - Journal of Physics G: Nuclear and Particle Physics

IS - 12

ER -