A description is given of experimental work on the damping ofa second order electron plasma wave echo due to velocity space diffusionin a low temperature magnetoplasma. Sufficient precision wasobtained to verify the theoretically predicted cubic rather thanquadratic or quartic dependence of the damping on exciter separation.Compared to the damping predicted for Coulomb collisions in a thermalplasma in an infinite magnetic field, the magnitude of the dampingwas approximately as predicted, while the velocity dependence of thedamping was weaker than predicted. The discrepancy is consistent withthe actual non-Maxwellian electron distribution of the plasma.
In conjunction with the damping work, echo amplitude saturationwas measured as a function of the velocity of the electrons contributingto the echo. Good agreement was obtained with the predicted J1Bessel function amplitude dependence, as well as a demonstration thatsaturation did not influence the damping results.
