Experimental Observation of the Deformation of the Electron Distribution Function due to a Damped Electrostatic Wave

The change in the electron distribution function due to a damped electron plasma wave is observed by means of an electron energy analyzer. The results show that the number of particles with velocities greater than that of the wave phase velocity is increased and that the number of particles with velocities less than the wave decreases. The distance between the antenna and analyzer is varied to show the increase in the deformation of the velocity distribution due to wave‐particle interaction through space. For sufficiently high wave power and large separation a plateau is formed in the vicinity of the wave phase velocity.