Electron momentum relaxation in non-collisional beam plasma

The theoretically predicted phenomenon of isotropisation of an intensive monoenergetic electron beam (MEEB) was shown for the first time in interactions with plasma oscillations, as a result of probe investigations in a non-collisional low-voltage discharge plasma in helium. The MEEB relaxation was shown to take place gradually: at first the process of isotropisation under constant beam energy is indicated by the energy relaxation of a weakly anisotropic beam to a state with a plateau-shaped electron velocity distribution function. The effective cross section of quasi-elastic electron-plasmon 'collisions' was estimated. (author)