Untersuchungen am Elektronenstrahlplasma

Abstract

The beam plasma exists in at least two states: The “quiescent” state with low pressures and the "turbulent" state with high pressures of the neutral gas (argon in most experiments). The quiescent state is described theoretically. It is shown that the system should transport growing waves with frequencies just below the upper hybrid frequency ωH2=ωp 2+ωc 2. These oscillations are found experimentally for ωp > k1 ωc, where k1 has a value of about 0.35 in the experiments described. Increasing the pressure and the plasma density as well raises the amplitude of the oscillations. Then at the critical pressure the turbulent state with high density is produced very abruptly. The essential feature of this second state is the high energy loss of the beam particles. The dependence of the losses on the parameters of the system is studied in detail. The maximum losses may attain 50% of the original beam energy. Some other properties of the system are described.