Oscillations Present in Plasma-Electron Heating by an Electron Beam

Oscillations of electrostatic fields present when electrons are strongly heated by electron-beam plasma interaction reveal large-amplitude oscillations with $\frac{\omega }{k_{\parallel }}\lesssim v_b$, the electron-beam speed; $\omega \approx \frac{{\omega }_{\mathrm{ce}}}{10}$, where ${\omega }_{\mathrm{ce}}$ is the electron gyrofrequency; coherence lengths of roughly a few wavelengths (« plasma length); and maximum electrostatic potential in the wave approaching the applied beam voltage. A gross compatibility is found between the observed frequencies and wavelengths and the predictions of a linear theory.