A remarkable example of non-neutral plasmas interacting was recorded in 1994 by the O'Neil/Driscoll/Dubin group at the University of California in San Diego.
The two electron plasmas are created in the same trap and begin life as two long cylinders side by side and revolving about each other under the combined action of repulsive electric field and confining magnetic field. The density profiles are recorded in a time sequence 1,4,7.. usec after initial formation. The false color code has red for the densest regions.