OL AV ESRF VACUUM GROUP 05 Preventive Maintenance

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation Michael Hahn reporting for Jean-Louis Bersier, Francis Bodart, Emmanuel Burtin, Dominique Cognie, Gilles Debut, Franck Demarcq, Michel Garrec, Pierre Guerin, Roberto Kersevan, Gildas Le Flem, Laurence Loiacono Levet, Gérard Luce, Isabelle Parat, Daniela 11 / 12 April 2005 Schmied, Jacqueline Tucek and

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • Storage Ring machine parameters – Circumference 844 m – E = 6 Gev – 200 (250) m. A multibunch – 90 m. A 16 bunch – Vertical emittance 0. 025 nm • Booster machine parameters – Circumference 300 m – Repetition rate 10 Hz 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • Storage Ring Vacuum System – Stainless Steel 316 LN Vacuum chambers connected by CF 150 flanges – Lumped pumping by SIP Varian Starcell…. – and NEG St 707 cartridges by SAES – Two long / three short machine shutdowns per year – In-situ baking equipment installed 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • • • Beam-Lifetime is the key quality parameter as far as vacuum is concerned, we obtain 80 hrs at 200 m. A in uniform mode Especially the modifications in the straight sections with the goal of an increased synchrotron light brilliance are critical for restarts: Quick conditioning is crucial in order to obtain acceptable Bremsstrahlungs. Level in the Beamline hutches ESRF follows two main directions to increase the brilliance – low gap Insertion Device vacuum chambers (10 mm externally) with distributed pumping provided by NEG coating produced in-house at ESRF under CERN license – In Vacuum Undulators allow the magnets to come even closer to the electron beam (5. 5 mm), the vacuum tank is equipped with massive pumping by Ti Sublimators, SIPs and a 500 l/s St 707 NEG cartridge 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • topics. . – Definition Preventive Maintenance / Downtime of Accelerators – Control System tools / Systematic Vacuum failure analysis – Additional machine data analysis for correlation – Temporary repair during Machine Shifts – Final repair / Machine Shutdown philosophy: To bake or not to bake…. – Discussion 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • The goal of our activities is to keep the unscheduled downtime of the accelerators due to vacuum as low as possible: One important parameter for the overall performance of the ESRF is (unwanted downtime / scheduled user hours) * total budget ESRF – all interventions and repairs should therefore take place during scheduled downtimes 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • Control System tools 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation This dynamic tool based on the ratio of normalised pressure in a given filling mode, helps us to detect : -In USM, air leaks at a very early stage (ratio > 2) -Ratio >5 signifies real problem on the SR (SR hitting vacuum chamber wall etc. ) Air leak 11 / 12 April 2005 - In MDT, quick pressure peaks can be correlated with HOM’s in the RF cavity areas or bad RF finger contacts in an a transient bellow vacuum vessel can be identified

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation The application is programmed in Labview for Unix, it gives the possibility to compare the vacuum situation in a given mode of the Storage Ring (16 bunch, 1/3, 2/3, hybrid, single, uniform and “exotic” modes) to a stored known as “good” situation. As the data is presented as a factor compared to the reference for all relevant pressures of the SR we can identify degradation or potential vacuum problems in a single view. To store a “reference” situation the application provides a “Save” function that asks for the operation mode and stores the data accordingly with the actual time and date. This data set will be stored independent from the historical database which increases the availability time (HDB data would be saved for one year online, older data on tape). As an additional tool we have LINUX PCs in each cell that store permanently on a FIFO base all the vacuum data with 1 Hz, the intelligence of this “interface PCs” allows also to trigger a higher sampling rate for HDB when something is “happening” on the gauges. The ion pump current is monitored permanently to have an additional confirmation of p behaviour The early recognition of air leaks by means of these methods made that since 2001 all leak detections could be carried out during scheduled downtimes 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation • Additional machine data analysis for correlation Lifetime (h) Change of the slopes on the pressure curve as well as on the lifetime profile 11 / 12 April 2005 Integrated dose (A. h) pressure (mbar)

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation Beamloss detectors cartography 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation The beamloss detectors are scintillators connected to each of the 64 dipole chambers on the SR, a MATLAB application allows to present the data representative and time-resolved. Differing from the real-time buffer as described for “vacgauge” this appliction recalls data from HDB (one hour from the desired starting time) We use also Bremsstrahlung data from XBPMs and a dedicated ionisation chamber in ID 6 beamline hutch to qualify the conditioning of new ID vacuum chambers 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation pressure (mbar) CV 9 (ion pump current) CV 11 (penning gauge) 11 / 12 April 2005 Helium detection + Repair

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation 1. Identification of the leak, localization prediction by reading gauges and SIP currents location: Precision in the range of 1 m 2. Leak detection during machine dedicated time, temporary fixing with varnish 3. Exchange of the Vacuum chamber during ESRF machine shutdown, with bake or warming depending on amount of new surface area - update of the history file 4. Improvements of spare chamber design following 11 / 12 April 2005 analysis of the failure

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation CELL 15 CELL 16 CV 2 CV 4 C 15 -2 CROTCH 1 CV 11 mbar m. A CV 2 CV 11 CROTCH 2 CV 4 CROTCH 1 C 15 -1 C 16 -1 C 17 -1 C 14 -7 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation Due to the water leak on a special absorber (one of a kind) we had to change absorber, dipole chamber, crotch chamber and re-baked the system after careful optical inspection with the endoscope During the restart this weekend we could recover quickly a reasonable average pressure and obtained (yesterday) lifetimes in the > 70 hrs @ 200 m. A 11 / 12 April 2005

OL AV ESRF VACUUM GROUP 05 Preventive Maintenance for Storage Ring Operation ACKNOWLEDGEMENTS The first part of this presentation reports on work initiated and realized by Daniela Schmied, Isabelle Parat and the ESRF Vacuum Measurement & Analysis subgroup. Special thanks to the ESRF Computing Services. Thank you: Gilles Chazot, Graham Naylor, Laurent Farvacque 11 / 12 April 2005