Visualization of 4-D particle data sets

We examine the phase space evolution of electrons under the influence of two counter-propagating electrostatic waves that move obliquely to an ambient magnetic field. The waves are driven by proton beams and their interaction with the electrons yields phase space structures that involve one spatial and three velocity components. We show how using color allows us to integrate the full four-dimensional electron data provided by a particle-in-cell (PIC) simulation into a single image. We find an initially developing antisymmetric electron phase space distribution and what appears to be a locking of the phase of the trapped electrons relative to the magnetic field. The phase space distribution at later times shows that there is no separatrix between the trapped electron islands of both waves.