Ricerc@Sapienza

Active plasma lenses are promising technologies for the focusing of high brightness electron beams due to their radially symmetric focusing and their high field gradients (up to several kT/m). However, in a number of experimental situations, the transverse non-uniformity of the current density flowing in the lens causes beam emittance growth and increases the minimum achievable spot size. To study the physics of the capillary discharge processes employed as active plasma lenses, we developed a 2-D hydrodynamic computational model.

Beam injection and extraction from a plasma module is still one of the crucial aspects to solve in order to producehigh quality electron beams with a plasma accelerator. Proper matching conditions require to focus the incominghigh brightness beam down to few microns size and to capture a high divergent beam at the exit without loss ofbeam quality. Plasma-based lenses have proven to provide focusing gradients of the order of kT/m with radiallysymmetric focusing thus promising compact and affordable alternative to permanent magnets in the design oftransport lines.

The current activity of the SPARC_LAB test-facility is focused on the realization of plasma-based accelerationexperiments with the aim to provide accelerating field of the order of several GV/m while maintaining theoverall quality (in terms of energy spread and emittance) of the accelerated electron bunch. In the following,the current status of such an activity is presented. We also show results related to the usability of plasmas asfocusing lenses in view of a complete plasma-based focusing and accelerating system