Properties of the electron beam in a room-temperature electron beam ion source investigated by position sensitive x-ray detection

The evolution of the charge state distribution inside an electron beam ion source or trap (EBIS/T) is determined by interactions of the electron beam with the ions in the trap region. Hence, detailed information about the electron beam is required for evaluations of spectroscopic and ion extraction measurements performed at EBIS/T facilities. This article presents the results of investigations on the electron beam properties of an ion source of the Dresden EBIS type. For the first time theoretical predictions of the shape of the beam were tested for a noncryogenic EBIS working with low magnetic flux densities provided by permanent magnets. Position and width of the electron beam were measured at different electron energies showing an oscillation in the beam structure. At an energy of $Ee=16keV$ and an emission current of $Ie=30mA$ the beam is compressed to a radius of $re=57μm$ (80% current). This refers to an average current density of $⟨je⟩=232A/cm2$⁠.