ABSTRACT
This chapter shows that the linear theory of electron-ion and electron-electron instabilities is in good agreement with the experimental data on the thresholds of beam excitation of oscillations and on their dispersion properties. Until the mid-1960s, the experimental data on the limiting currents of a quasineutral electron beam were incomplete and largely contradictory. The beam instability in the experiments was caused by the interaction of two components of the system: beam particles and one species of particles of a fixed medium. The chapter considers the effect of the third component, that is, of the electrons of the 'excess' plasma injected into the quasineutral electron beam, on the thresholds of the electron-ion instabilities and of the Pierce instability. The beam propagated in vacuum, there was no beam charge neutralization and a strong external magnetic field along the beam direction was present.
