Self-pulsing of electron transmission by a transversal magnetic field
  The distribution of scattering delay times is analyzed for classical electrons which are transmitted through a finite waveguide. For non-zero magnetic field the distribution shows a regular pattern of maxima (logarithmic singularities). Although their location follows from a simple commensurability condition, there is no straightforward geometric explanation of this self-pulsing effect. Rather it can be understood as a time-dependent analog of transverse magnetic focusing, in terms of the stationary points of the delay time. We also discuss the possibility of singularities in the delay-time distribution for generic 2D scattering systems. 
Manamohan Prusty and Holger Schanz