NEG COATING RESULTS AND TRENDS R Kersevan Vacuum

NEG COATING RESULTS AND TRENDS R. Kersevan, Vacuum Group, Tech. Serv. Division, ESRF, Grenoble ALBA-Max. Lab Workshop on Vacuum Systems for Synchrotron Radiation Light Sources, Barcelona, 12 -13 Sept 2005 1

Status of NEG-Coated ID Chambers for RUN 05 -4 (18/8 – 17/10/2005): NEG-COATED CHAMBERS: 10 mm ALU CV 5073: 11 x 15 mm ALU CV 5073: 2 x 15 mm ALU CV 2093: 4 x 10 mm SS CV 5175: 1 x Total NEG-coated length, m: 79. 5 • NO ADVERSE EFFECT ON RESISTIVE-WALL IMPEDANCE* • LONG-TERM STABILITY (>5 YRS) ESTABLISHED • PROGRAM OF UPGRADE OF REMAINING (6+1) 15 -19 mm CHAMBERS (SS NEG/Al) UNDERWAY *T. Perron, “Single Bunch-Related Impedance Measurements on the ESRF Storage Ring", Ph. D thesis, November 2005, Université Joseph Fourier, Grenoble 2

Cross-Sections of NEG-Coated ID Chambers: “ 10 mm” SS CV 5175 (50 x 8 mm 2 version) 1 left in the ring (ID 28), obsolete design “ 15 mm”extruded-Al CV 5073/2093 (2 x CV 5073 + 4 x CV 2093) “ 10 mm”extruded-Al CV 5073 (11 x CV 5073) (CV 2093 version under design) 3

“Pump-less”Quadrupole-Type Vacuum Chambers: Fact: The ESRF has in excess of 700 lumped pumps installed around the ring Q: “Does the vacuum engineer of a state-of-the-art SR light source need all those expensive, appendage pumps and the related power supplies and cabling? ” A: “If we believe the results of 5+ years of machine operation at the ESRF (and Elettra), the answer might be ‘NO’ ” • • Proven fact: pump-less chambers, characterized by extremely low conductances, have been operated without major effects on the operation of the 6 Ge. V light source for over 5 years. Long-term issues settled: no need for re-activation unless vented. One chamber activated 6 times (vented 4), and still good Why? Because the NEG-coating technology has removed the need for appendage pumps, by reducing drastically the SR-induced gas load CV 3 chamber of cell 6: 3. 53 m long, 3 pumping ports, 2 x GP 200 + 1 x 45 l/s SIP installed; SS with OFH Cu absorber (brazing, eb-welding) Two types tested: Soleil extrusion and “Esrf-2” extrusion Prototypes coated in-house and installed in Cell 6 Vacuum and bremsstrahlung conditioning followed closely Both the Soleil-type and the ESRF-2 type have been successful 4

CV 3 -Type Vacuum Chambers, 3530 mm long: GP 200 45 l/s Star. Cell Standard CV 3 chamber: 2 x. NEG + 1 SIP ESRF-2 extrusion: 30 x 20 mm 2 (Hx. V) Hi-temp brazing of Cu absorber ; precision eb-welding of SS parts chamber NO pumps, only NEG-coating Soleil-type CV 3: Al extrusion 70 x 35 mm 2; NO pumps, only NEGcoating 5

Vacuum and Bremsstrahlung Measurements of NEG-Coated Vacuum Chambers on cell 6/ID 6: • Each new NEG-coated CV 5000 is pre-installed and pre-conditioned on ID 6, where its bremsstrahlung level can be measured precisely (dedicated hutch). Very effective way (the only way) of characterizing vacuum inside the ID chamber • The conditionings of Soleil- and ESRF-2 -type CV 3 chambers have been monitored on ID 6’s hutch Extra gauges, measuring along the chamber RUN 05 -1 RUN 05 -3 6

Vacuum Conditioning of a Standard ESRF-type CV 3 Chambers: RUN 05 -4: new CV 3 RUN 02 -1: new CV 3 7

Comparison of Standard and Pump-less CV 3 s Conclusions: • • • Comparable, if not better, pressures (PEN 4) Comparably low, if not better, bremsstrahlung levels (not discussed in detail here) Much easier fabrication, lower cost NEG-coated types allow much smaller quadrupole and sextupole openings, ideal for advanced machine, with demanding lattices No need for many appendage pumps, and all that goes with them (cabling, power supplies, control software, etc…). Only places where ion-pumps would be needed is at (crotch) absorbers What is needed: A new project which dares implementing the pump-less concept on a global scale 8

ESRF: R&D and Chamber Production: • • A second NEG-coating tower is being commissioned now, and production of NEG-coated chambers for some of Soleil’s in-air IDs is underway New tower is equipped with 2 m-long (1. 9 m effective length) solenoid, with increased field (first system has 1 m-long, 80 cm-effective length) New tower has movable upper fixation point, allowing easier handling of short chambers (Soleil, SLS) Still some open issues concerning quality of NEG coating: had to reject a couple of chambers (10 mm extruded alu ESRF CV 5073) Chemical stripping of NEG film seems to be the cause of some failures Testing Soleil’s quadrupole chambers (1556 mm long, with pumping ports) on D 31 Lower limit on the size/cross-section of ‘coatable’ chambers seems to have been reached: the 57 x 8 mm 2 “ 10 mm” cross-section: no way to coat smaller chambers, unless new technology is discovered 9

Many thanks to…: -The “NEG-Coating Team” – E. Burtin (software) F. Demarcq, I. Parat (deposition and assembly) M. Hahn, R. Kersevan (supervision, planning, R@D) D. Cognie, F. Bodart (mechanical set-up) V. Marion (Soleil contract) G. Debut (measurements on D 31, D 15) B. Plan (Mech. Engineering Group) (design of tools and chambers) The constant support and encouragement of the present (P. Elleaume) and past (JM. Filhol) machine directors is gratefully acknowledged 10