Advanced copper lining for accelerator components

We developed a pure copper lining process for RF cavities using a new copper electro-forming, a periodic reverse copper electro-forming (PR process) with a low Cu-content acid copper sulfate bath which contains no organic additives. The PR process offers pure copper that contains impurities less than 35 ppm or so, and that has equivalent IACS (International Annealed Copper Standard) value to that of oxygen-free copper. The lining process can be applied to complex accelerator components such as hollow coils for quadruple magnet. We produced the trial mode of DTL (drift tube linac) by using this new electro-formed copper lining process and achieved high vacuum and excellent Q value. (author)