Direct observation of strong wave/particle interactions in electron-beam-driven plasma wave bursts

We present detailed observations of bursting wave behavior at f≃fpe/2 driven by an electron beam in a laboratory plasma, including high-time-resolution measurements of the wave bursts' interaction with the electron beam. A burst of wave activity is observed when a threshold electron beam density relative to the background plasma density is exceeded. Wave bursts varying in their time duration are observed, but the fundamental structure of the bursts appears to be structures with a symmetric time envelope. Wave bursts with amplitudes large enough to substantially heat the electron beam, disrupt the beam, and eventually trap beam electrons at the phase speed of the waves are observed. These behaviors observed in the laboratory are able to be reproduced via numerical simulations. The laboratory results are applicable to a variety of conditions in space plasmas.