Development of a plasma lens as a fine focusing lens for heavy-ion beams

Within the framework of the “High Energy Density in Matter” program, a plasma lens has been designed to focus a heavy-ion beam onto a 200 µm diameter spot (FWHM). This value is desired to get the necessary energy density on the target to create a plasma by means of a heavy-ion beam. It is determined by the parameters of the SIS-accelerator at GSI-Darmstadt. The calculated discharge current in an ideal plasma lens has to be between 300 and 400 kA for an emittance limited spot, dependent on initial beam radius and distance of the spot from lens exit. A flexible system has been built in order to investigate the various discharge mechanisms and their influence on the focusing properties at these high currents. Design considerations, the first beam tests and investigations of the plasma development at plasma lens currents up to 200 kA are discussed.