Simulations on the effect of internal structure of shock fronts on particle acceleration

We have studied the effect of internal structure of shock fronts on their efficiency of particle acceleration. We present a simple model of the width of a, parallel shock front depending oil the spectral index of the ambient magnetic turbulence. Using Monte-Carlo simulations, we determine the spectral index of energy distribution of shock accelerated particles in this model as well as in a case, where the shock width is independent of the ambient turbulence. In both cases, the acceleration capability of a wide shock structure is shown to be much smaller than for a step-like shock front.