EXPERIENCES ON IMPROVED CAVITY PREPARATION CYCLES WITH A VISION ON INDUSTRIALIZATION OF THE XFEL CAVITY PREPARATION

Abstract Within the last decade the production and preparation of superconducting resonators became more and more stable at DESY. Two cycles for the final surface preparation, the final surface removal by electro polishing (EP) and the final surface removal by a short buffered chemical polishing (BCP flash) are the baseline of cavity surface preparation at DESY. Basing on the positive development overtime and in view of industrialization of the processes for the XFEL project, a proposal for a reduced number of work steps was presented on the SRF 2007 workshop in Beijin

UPDATE ON THE JRA1 PROJECT RESULTS OF ELECTRO-POLISHING OF MULTI-CELL SUPER CONDUCTING RESONATORS

Abstract Under the contract RII3-CT-2003-506395 of the European Union improvement on the electro-polishing (EP) of multi cell resonators are made. Several methods to improve resonator performances are studied. Improvement of electrode shape, simulated by numerical computer codes and test set ups are presented. With respect to reproducible cavity performances and industrialization of the EP process, a study for quality control by acid management is started. An automated EP system is developed at INFN Legnaro / Italy and within the collaboration of Legnaro and DESY this automated steering will be integrated into the DESY EP facility. We will report on the status of the WP 5.2.2.and the progress of the transfer of the automated E

UPDATE ON QUALITY CONTROL OF ELECTRO POLISHING ACID

Abstract Electro-polishing has become one of the leading surface preparation processes to reach high gradients in superconducting cavities. For industrialization and for reproducible results in the electro-polishing process a study on acid quality control and quality management was launched under the scope of the European investigations under the CARE. First results of this acid management studies were presented at the TTC meeting 2006 and the JRI-SRF summary reports 2008 A second study with experimental results on the quality control methods proposed was launched where the different methods and instrumentations for acid quality control are studied in detail. We present the results of this following up investigations made on acid quality control for the electro-polishing mixture applied at DESY

Update on Large Grain Cavities with 45 MV/m in a Nine-Cell Cavity at DESY.

Since 2009 a series of eight nine-cell cavities (AC151 – AC158) of TESLA shape fabricated of large grain (LG) niobium material is under preparation and test at DESY. In a first step all cavities were tested after a BCP treatment. In a second step additional electro polishing is applied to all cavities. In this paper the treatment will be discussed and a first excellent result of AC155 will be reported

A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

International audienceThe European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created