Successful large-scale copper plating: GSI Electroplating achieves important milestone for FAIR


An important success has been achieved in the Electroplating Department of the GSI Helmholtzzentrum für Schwerionenforschung: The copper plating of a cavity with two meter in diameter was successfully realized. This is also of great importance for the future accelerator center FAIR. In order to achieve the FAIR parameters, the existing linear accelerator UNILAC, which will serve as a pre-accelerator in the future, has to be partially upgraded with new cavities.

Cavities or cavity resonators are central elements of accelerators. Therein, strong electromagnetic fields oscillate, transferring their energy to the particles flying along the tube axis. To improve electrical conductivity, the surfaces are copper-plated. At GSI and FAIR, the Electroplating Department is responsible for coating the tanks and components of the particle accelerators with a layer of high-gloss copper from inside. The task of electroplating is challenging, the demands on surface quality are high.

Currently, the Alvarez accelerator structure, a section of GSI-UNILAC, has to be replaced for future top performance so that FAIR can deliver the planned high beam quality. One of the critical points in this upgrade is the copper plating of particularly large cavity sections. This is a challenge that was last faced at GSI more than 20 years ago. Nevertheless, the GSI Electroplating Department has now succeeded in demonstrating its ability to copperplate a cavity of this size on the very first attempt. Thus, a very crucial aspect of the Alvarez replacement has been addressed and positively solved.

The electroplating facility, which has developed in the course of the accelerator expansion on the GSI and FAIR campus, is unique. It allows high-polish copper plating of metal surfaces such as steel and stainless steel up to 200 micrometers thickness. It is above all the size of the elements to be copper-plated that makes the plant exceptional. Even a crane is used during maneuvering to move the heavy components back and forth between the various cleaning and coating baths. Elements can be copper-plated up to a maximum length of 2.5 meters and a diameter of up to 2.5 meters. (BP)