Diocotron instability of electron beams in magnetic gaps in a magneto-electrostatic trap

Low-frequency (ω<<ωc, ωc - electron cyclotron frequency) potential oscillations excited in the electron layer are investigated; the electron layer consists of runaway and trapped electrons in magnetic gaps of magneto-electrostatic trap. It is shown that the existence of two groups of electrons results in an insignificant decrease of the maximum value of increment occurrence of additional oscillation branches and expansion of wave length instability region as compared with the electron layer consisting of only one type of electrons. Diocotron oscillations are always instable in the presence of even a small fraction of runaway electrons and vacuum gaps between the electron layer and metal walls