Experimental study on excitation and suppression of a multimode beam-plasma instability in a bounded system

Experimental study on excitation and suppression of a multimode beam-plasma instability in a bounded system

Creators Fukumasa O.

Creators Fukumasa Osamu

Four or five longitudinal electron waves of axial beam modes are excited simultaneously in a bounded electron beam-plasma system. They are accompanied with an ion-acoustic wave of an axial mode under appropriate plasma conditions. This ion-acoustic wave can not be excited directly by beam-plasma interaction, where v_b/v_<te>≧3. When a beam density is modulated by an external r.f. signal whose frequency is close to any one of frequencies of electron waves excited spontaneously, all of the electron waves and the ion-acoustic wave are suppressed simultaneously. It is verified experimentally that quenching of the ion-acoustic wave is not brought about directly by the beam modulation, but by the damping of the electron wave which constitutes an energy source of the ion-acoustic wave.

[ISSN]0032-1028

[NCID]AA0077562X