Optical investigation of intense electron beams and target plasma

Wladimir An, Georg Müller, Hansjoachim Bluhm, Vladimir Engelko*

*Efremov Institut of Electrophysical Apparatus, St.Petersburg

abstract

Measurements of the spatial distribution of the beam current density in the GESA-facilities [1] shows that the current density oscillates in time although the total beam current is stable. To investigate the nature of these oscillations and the plasma formation process at the target surface, a special optical diagnostic system was developed. The most reasonable explanation for beam precession is the electron drift in crossed FxB-fields. The radial force F has electrical nature and can be caused either by the ions inside the transport channel or by induced wall charge. For the first case the target plasma is the most probable ion source [2]