Simulations of coronal shock acceleration in self-generated turbulence

Abstract We have recently presented a numerical model to simulate the acceleration and transport of energetic particles at coronal shock waves, which includes the back-reaction of the energetic particles on the Alfven waves responsible for their scattering in the ambient medium [Vainio, R., Laitinen, T., 2007. Monte Carlo simulations of coronal diffusive shock acceleration in self-generated turbulence. Astrophysical Journal 658, 622–630]. The model results imply that the acceleration of energetic protons to energies exceeding 100 MeV can occur in some minutes in parallel coronal shocks driven by fast CMEs. In this paper we give a detailed description of the numerical model and its foreseen extensions. We extend the parameter study presented in the first paper to cover (shorter and) longer time scales, and present the intensities observed in the interplanetary medium during the initial phases of an SEP event. We also study the scattering mean free path resulting from the self-consistent computations. Finally, the potential of the model to explain ion acceleration up to relativistic energies is discussed.

[1]  T. Horbury,et al.  The rate of turbulent evolution over the Sun's poles , 1996 .

[2]  G. Krymskiĭ.  A regular mechanism for the acceleration of charged particles on the front of a shock wave , 1977 .

[3]  Jeremiah P. Ostriker,et al.  Particle Acceleration by Astrophysical Shocks , 1978 .

[4]  A. Bell.  The acceleration of cosmic rays in shock fronts – I , 1978 .

[5]  W. I. Axford.  THE ACCELERATION OF COSMIC RAYS BY SHOCK WAVES , 1981 .

[6]  R. Vainio,et al.  Interplanetary and Interacting Protons Accelerated in a Parallel Shock Wave , 2000 .

[7]  Frank C. Jones,et al.  The plasma physics of shock acceleration , 1989 .

[8]  Martin A. Lee.  Coupled Hydromagnetic Wave Excitation and Ion Acceleration at an Evolving Coronal/Interplanetary Shock , 2005 .

[9]  W. Rice,et al.  Particle acceleration and coronal mass ejection driven shocks: Shocks of arbitrary strength , 2003 .

[10]  R. Vainio,et al.  Adiabatic Deceleration of Solar Energetic Particles as Deduced from Monte Carlo Simulations of Interplanetary Transport , 1998 .

[11]  K. Morton,et al.  Numerical Solution of Partial Differential Equations , 1995 .

[12]  Rami Vainio,et al.  On the generation of Alfvén waves by solar energetic particles , 2003 .

[13]  R. Vainio,et al.  Monte Carlo Simulations of Coronal Diffusive Shock Acceleration in Self-generated Turbulence , 2007 .

[14]  Rami Vainio,et al.  A simple analytical expression for the power spectrum of cascading Alfvén waves in the solar wind , 2003 .