Along a narrow road, two caravans approach each other. One is wide and slow, carrying a load of density. The other, a string of light carts with current, slips between the first. Thus, in a magnetron discharge, two structures coexist, rotating in opposite directions: a density spoke and current filaments.

For a long time, it was unclear how a large vortex and small ripples together transport electrons across the magnetic field. They built a computer model where each electron and ion is tracked individually, like caravan drivers on the road. The model reproduced the measured vortex: density rotates in one direction at 90 kHz, while current filaments rotate in the other at 1.0 MHz.

Now we can see how the two caravans share the road. Deep in the plasma, the vortex carries almost all the flow. Near the wall, turbulence takes over half. In between, the vortex is still ahead. The caravans move toward each other but do not hinder one another; they exchange energy with almost no net heating. This exchange is what sustains ionization at the vortex front. The results will help improve magnetron sputtering and Hall thrusters.