For parameters that are applicable to the conditions at young supernova remnants, we present results of twodimensional, three-vector (2D3V)particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at a  45 angle to the simulation plane to approximate three-dimensional (3D) physics. We developed an improved clean setup that uses the collision of two plasma slabs with different densities and velocities, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations due to shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales produced by the gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but is commensurate withÉ B drift. We observe a stable supra-thermal tail in the ion spectra, but no electron acceleration because the amplitude of the Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other twodimensional (2D) simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but the pre-acceleration efficacy might be reduced with respect to the 2D results once 3D effects are fully accounted for. Other microphysical factors may also play a part in limiting the amplitude of the Buneman waves or preventing the return of electrons to the foot region.

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For parameters that are applicable to the conditions at young supernova remnants, we present results of 2D3V particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field. We developed a new clean setup that uses the collision of two plasma slabs with different density and velocity, leading to the development of two distinctive shocks and a contact discontinuity without artificial transients that may limit the veracity of the simulation. The Alfvenic Mach number of both shocks is M A 30, whereas the sonic Mach numbers differ with values M s 250 and M s 750. Both the forward and the reverse shocks are mediated by a Weibel-like filamentation instability that produces mainly magnetic turbulence. We observe significant shock rippling and strong fluctuations in the turbulent shock structure, and also features of the shock self-reformation. Proton reflection at the shocks leads to shocksurfing acceleration that generates a moderate non-thermal tail in the particle spectra measured downstream, suggesting that few ions undergo more than one reflection cycle. Electrons are preaccelerated in a layer of Buneman waves at the shock foot, but are very efficiently isotropized upon passage through the shock ramp, and hence their downstream spectrum is quasi-thermal with high temperature. We note that electrons and ions show the same transverse drift in the ramp region, which is commensurate with ExB drift, but not the gradient drift that is usually invoked for shock drift acceleration. Thus, electrons loose energy by drifting. We discuss the impact of our findings on pre-acceleration of electrons at high-Mach-number perpendicular shocks and their injection into diffusive shock acceleration. First results of the studies of oblique quasiperpendicular shocks will also be presented.