In recent years, high-gradient, symmetric focusing with active plasma lenses has regained significant interest due to its potential advantages in compactness and beam dynamics compared to conventional focusing elements. A promising application could be optical matching of highly divergent positrons from the undulator-based ILC positron source into the downstream accelerating structures to increase the positron yield. In a collaboration between University Hamburg and DESY Hamburg a downscaled prototype for this application has been developed and constructed. Here, we present the current status of the prototype development.

In recent years, high-gradient, symmetric focusing with active plasma lenses has regained significant interest due to its potential advantages in compactness and beam dynamics compared to conventional focusing elements. A promising application could be optical matching of highly divergent positrons from the undulator-based ILC positron source into the downstream accelerating structures to increase the positron yield. In a collaboration between University Hamburg and DESY Hamburg a downscaled prototype for this application has been developed and constructed. Here, we present the current status of the prototype development.

The International Linear Collider is a proposed electron-positron linear collider, where the positron beam is generated by undulator radiation hitting a target. The resulting, highly divergent positron beam requires immediate optical matching to improve the luminosity and ensure the success of the intended collision experiments. Here, optical matching refers to the process of capturing particles and making them available for downstream beamline elements like accelerators. In the past, this has been done with sophisticated coils, but more recently the usage of a current-carrying plasma, a so-called plasma lens, has been proposed as an alternative. For the International Linear Collider, idealised particle tracking simulations have already been done in the past with the purpose of finding the optimal plasma lens design with respect to the captured positron yield. The proposed design is conical in shape to accommodate for the large beam divergence [1]. Now further research and development of this design is required, including both experiments with a downscaled prototype set-up as well as corresponding simulations modelling the hydrodynamics of the current-carrying plasma. The accuracy of the latter will benefit greatly from the former. In this work, first preliminary hydrodynamic simulations instil confidence into further endeavours.