Ground current in plastic target for ion sources.

Delle Side D., Krasa J., Nassisi V., Monteduro L., Buccolieri G., Caricato A.P.
  Venerdì 15/09   09:00 - 12:00   Aula A222   VI - Fisica applicata, acceleratori e beni culturali
It is known that exposure of targets to focused laser beams results in the occurrence of a time-varying current between the target and the grounded vacuum chamber. During ablation of polymers with an UV KrF laser, negative target current peaks are observed, whose origin is still unknown. The current values depend on the ratio between target and support surface. It has a maximum when the ratio is 1. We investigate the dependence of these current structures on the thickness of the target, using ultra-high molecular weight polyethylene disks of different diameter and thickness.