Within the next two years the 2.3 km long storage ring PETRA will be rebuild into one of the most brilliant x-ray sources worldwide (PETRA III). The large bending radius and the use of damping wigglers allow to achieve small beam emittances and extremely brilliant x-ray beams. In this paper we describe the design and the expected performance of the vacuum system for the storage ring. It consists of standard arc sections, an experimental octant which is equipped with undulators and several straight sections that include the damping wigglers. Because of the long length of the storage ring a cost effective solution had to be found. Besides the requirement to quickly provide acceptable residual gas pressures the technical challenges of the system include the provision of high thermal stability with respect to magnets and BPM's, and the design of thin walled insertion device chambers as well as high power synchrotron radiation absorbers.

Due to surface treatment with electro-polishing superconducting niobium resonators can potentially reach accelerating gradients well beyond 35 MV/m at a frequency of 1.3 GHz. The anticipated gradient for the 500GeV version of the TESLA collider is 23.4 MV/m. In view of the extendibility of the collider towards higher energies this technology is therefore of great importance for the TESLA project. In this paper we discuss the engineering aspects of the planned electro-polishing facility at DESY. The facility will allow for the treatment of single cell cavities as well as the standard TESLA 9-cell structure, and also a so called superstructure that consists of 2x9 cells. The issues described cover the acid circulation including cooling requirements, the required current densities resulting in the specifications of the electrical circuit, removal of oxyhydrogen gas, rotating feed-through and the overall mechanical layout. Furthermore we report on recent tests of critical components.

Electro polishing of Niobium was invented in the 70 ’ sb y Siemens. Due to research in the last decade at KEK and CERN acceleration voltages around 40 MV/m were established in single cell treatment and first encouraging results were reached in multi-cell treatments done at KEK in collaboration with Nomura Plating company. To study the electro polishing on multi-cell structures of TESLA a facility for electro polishing is under construction at DESY. It will be located in an annex to the existing cleanroom at DESY where the cavity treatment of the 1.3 GHz resonators for TTF takes place. The hardware is designed to handle 1.3 GHz single cells as well as multi-cell resonators up to the 2 x nine cell superstructure as described in the TESLA Design Report. We report on the infrastructure, the hardware and the general layout of the facility and the status of the activities. A flow scheme of the designed incorporation of the electro polishing into the standard handling and treatment sequence will be presented.