THIN FILM GETTER COATING FOR THE SIS 18 UPGRADE M.C.Bellachioma GSI- Vacuum Group Beschleunigerpalaver 14 September 2006
THIN FILM GETTER COATING FOR THE SIS 18 UPGRADE The SIS 18 upgrade: requirements and strategy Non evaporable thin films getter: definition and properties The magnetron sputtering facility Characterization techniques for the produced coated chambers Conclusions
The FAIR project/Stage 1 M. C. Bellachioma, Beschleunigerpalaver, 14 September The realization of the FAIR project will be achieved in 3 stages
The FAIR project/Stage 1 M. C. Bellachioma, Beschleunigerpalaver, 14 September The realization of the FAIR project will be achieved in 3 stages
The FAIR project/Stage 1 M. C. Bellachioma, Beschleunigerpalaver, 14 September The realization of the FAIR project will be achieved in 3 stages In the stage 1 The SIS 18 will be upgraded and will serve as high energy accelerator, providing the primary beam for the radioactive beam program involving the Super Fragment Separator and the connected storage rings CR and NESR
The SIS 18 Upgrade: Requirements and Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September Beam lifetime has to be significantly larger than cycling time of the SIS18 (Lifetime of at least 10 seconds for all kinds of operation)
The SIS 18 Upgrade: Requirements and Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September Beam lifetime has to be significantly larger than cycling time of the SIS18 (Lifetime of at least 10 seconds for all kinds of operation) Total pressure lower 1∙ mbar with a small fraction of high Z gases even for highest beam intensities
The SIS 18 Upgrade: Requirements and Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September Beam lifetime has to be significantly larger than cycling time of the SIS18 (Lifetime of at least 10 seconds for all kinds of operation) Total pressure lower 1∙ mbar with a small fraction of high Z gases even for highest beam intensities optimized dynamic conditions: efficient ion beam loss control, low desorption at localized ion beam losses ( Desorption / ERDA Experiments), maximized local pumping speed at locations of ion beam loss ( collimation Desorption / ERDA). optimized static conditions: minimized outgassing rate by material and production control, cleaning, bakeout (quality control established), removal of contaminations or "micro-leaks" ( measurements during shutdowns on TSP + SIP) first “big shutdown”: 9/2006
The SIS 18 Upgrade: Requirements and Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September Beam lifetime has to be significantly larger than cycling time of the SIS18 (Lifetime of at least 10 seconds for all kinds of operation) Total pressure lower 1∙ mbar with a small fraction of high Z gases even for highest beam intensities optimized dynamic conditions: efficient ion beam loss control, low desorption at localized ion beam losses ( Desorption / ERDA Experiments), maximized local pumping speed at locations of ion beam loss ( collimation Desorption / ERDA). optimized static conditions: minimized outgassing rate by material and production control, cleaning, bakeout (quality control established), removal of contaminations or "micro-leaks" ( measurements during shutdowns on TSP + SIP) first “big shutdown”: 9/2006 efficient and distributed pumping NEG coating
Definition of NEG M. C. Bellachioma, Beschleunigerpalaver, 14 September Getters are materials capable of chemically adsorbing gas molecules. To do so their surface must be clean. For Non-Evaporable Getters a clean surface is obtained by heating to a temperature high enough to dissolve the native oxide layer into the bulk.
Definition of NEG M. C. Bellachioma, Beschleunigerpalaver, 14 September Getters are materials capable of chemically adsorbing gas molecules. To do so their surface must be clean. For Non-Evaporable Getters a clean surface is obtained by heating to a temperature high enough to dissolve the native oxide layer into the bulk. The getter materials should provide: high binding energies for reactive gases; high absorption capacity; high oxygen diffusivity to allow reasonable low activation temperature; high oxygen solubility limit to allow many venting-air exposure cycles. La High O solubility limit
NEG film coatings properties M. C. Bellachioma, Beschleunigerpalaver, 14 September Non-Evaporable Getter thin film coatings, produced by sputtering, after in-situ activation provide: 0.5 l s -1 cm -2 for H 2 5 l s -1 cm -2 for CO Large and uniformly distributed pumping speed for most of the residual gases: ≈ 0.5 l s -1 cm -2 for H 2 and ≈5 l s -1 cm -2 for CO (CH 4 and rare gases are not pumped by NEGs). Monolayer Monolayer surface capacity for saturating gases. Photon and electron desorption yields lower than those for standard vacuum materials. Very low SEY (≈1.1 peak value) NEG films trap the gas coming from the substrate material (no more distinction between degassing and capturing surfaces). o NEG films trap the gas coming from the substrate material (no more distinction between degassing and capturing surfaces). o The role of the structural material can be separated from that of the vacuum material.
NEG applications M. C. Bellachioma, Beschleunigerpalaver, 14 September At present, Ti-Zr-V coatings are already in use to: Reduce bremsstrahlung radiation produced in undulators for synchrotron radiation facilities (ELETTRA, ESRF). Eradicate the problem of electron cloud instability in high energy proton accelerators (RHIC,..).
NEG applications M. C. Bellachioma, Beschleunigerpalaver, 14 September At present, Ti-Zr-V coatings are already in use to: Reduce bremsstrahlung radiation produced in undulators for synchrotron radiation facilities (ELETTRA, ESRF). Eradicate the problem of electron cloud instability in high energy proton accelerators (RHIC,..). Many new accelerators will profit from the NEG technology: FAIR (SIS 18 upgrade) LHC (6 km of Long Straight Sections) ALBA SOLEIL DIAMOND
The SIS 18 Upgrade: Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September First step of the SIS upgrade: Mounting (during the actual shutdown) in 1 sector 2 coated dipoles and 1 coated quadrupole
The SIS 18 Upgrade: Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September First step of the SIS upgrade: Mounting (during the actual shutdown) in 1 sector 2 coated dipoles and 1 coated quadrupole
The SIS 18 Upgrade: Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September First step of the SIS upgrade: Mounting (during the actual shutdown) in 1 sector 2 coated dipoles and 1 coated quadrupole
The SIS 18 Upgrade: Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September First step of the SIS upgrade: Mounting (during the actual shutdown) in 1 sector 2 coated dipoles and 1 coated quadrupole
The SIS 18 Upgrade: Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September mm mm 4 m First step of the SIS upgrade: Mounting (during the actual shutdown) in 1 sector 2 coated dipoles and 1 coated quadrupole
The SIS 18 Upgrade: Strategy M. C. Bellachioma, Beschleunigerpalaver, 14 September mm mm 4 m 190.7mm 70.7mm 3 m 15° bending angle 0,3 mm wall thickness First step of the SIS upgrade: Mounting (during the actual shutdown) in 1 sector 2 coated dipoles and 1 coated quadrupole
The SIS Quadrupole chambers M. C. Bellachioma, Beschleunigerpalaver, 14 September In April 2005 a license agreement (N°.: K1157/TT/TS/02L) for non-evaporable thin film getters was established between CERN and GSI, and in the frame of the technology transfer the first quadrupole chamber has been coated at CERN in December 2005.
The SIS Quadrupole chambers M. C. Bellachioma, Beschleunigerpalaver, 14 September In April 2005 a license agreement (N°.: K1157/TT/TS/02L) for non-evaporable thin film getters was established between CERN and GSI, and in the frame of the technology transfer the first quadrupole chamber has been coated at CERN in December o Coating units
The SIS Quadrupole chambers M. C. Bellachioma, Beschleunigerpalaver, 14 September In April 2005 a license agreement (N°.: K1157/TT/TS/02L) for non-evaporable thin film getters was established between CERN and GSI, and in the frame of the technology transfer the first quadrupole chamber has been coated at CERN in December o Coating units
The SIS Quadrupole chambers M. C. Bellachioma, Beschleunigerpalaver, 14 September In April 2005 a license agreement (N°.: K1157/TT/TS/02L) for non-evaporable thin film getters was established between CERN and GSI, and in the frame of the technology transfer the first quadrupole chamber has been coated at CERN in December o Coating units
The SIS dipole chambers: sputtering facility M. C. Bellachioma, Beschleunigerpalaver, 14 September To build the dipole coating facility we had to consider:
The SIS dipole chambers: sputtering facility M. C. Bellachioma, Beschleunigerpalaver, 14 September To build the dipole coating facility we had to consider: o the chamber bending angle (15°) horizontal mounting How to integrate the dipole chamber into the sputtering system?
The SIS dipole chambers: sputtering facility M. C. Bellachioma, Beschleunigerpalaver, 14 September To build the dipole coating facility we had to consider: o the chamber bending angle (15°) horizontal mounting How to integrate the dipole chamber into the sputtering system? 40 cm One coil is removed
The SIS dipole chambers: sputtering facility M. C. Bellachioma, Beschleunigerpalaver, 14 September To build the dipole coating facility we had to consider: o the chamber bending angle (15°) horizontal mounting o elliptical aperture 2 cathodes for uniform coating
The SIS dipole chambers: sputtering facility M. C. Bellachioma, Beschleunigerpalaver, 14 September To build the dipole coating facility we had to consider: o the chamber bending angle (15°) horizontal mounting o elliptical aperture 2 cathodes for uniform coating Magnetron sputtering was chosen to perform the coating B V - 500
The SIS dipole chambers: sputtering facility Power Supplies, Controllers Computer Coil dimensions: L = 800 mm =350 mm Each coil is powered independently Pumping unit M. C. Bellachioma, Beschleunigerpalaver, 14 September 2006.
The coating parameters M. C. Bellachioma, Beschleunigerpalaver, 14 September Discharge gas -> Kr Current I -> 0,4 A Potential U -> -500 V Pressure -> 7x10-3 Torr Magnetic field -> 180 G Supply atoms for the ionization process. Defines the energy of the ions. Deposition rate -> 0.1 m/h => Increase the ionization efficiency improving stability and allowing lower discharge pressure Defines the rate of the ions hitting the cathode. Noble gas. Kr chosen in order to minimize the discharge gas trapping on the coating. 10h for a 1 m coating
The SIS dipole chambers: how we proceed… Before coating Visual inspection of the dipole chamber; Leak detection M. C. Bellachioma, Beschleunigerpalaver, 14 September 2006.
The SIS dipole chambers: how we proceed… Before coating Visual inspection of the dipole chamber; Leak detection During coating The voltage and current of the cathode and the Kr pressure are continually monitored. Additionally the partial pressure evolution is recorded (particular attention is given to the mass 20). M. C. Bellachioma, Beschleunigerpalaver, 14 September 2006.
The SIS dipole chambers: how we proceed… Before coating Visual inspection of the dipole chamber; Leak detection During coating After coating Visual inspection of the coated chamber; Surface analysis: SEM, EDX, XPS (for the moment performed at CERN) and in future ERDA. Evaluation of the sticking coefficient. The voltage and current of the cathode and the Kr pressure are continually monitored. Additionally the partial pressure evolution is recorded (particular attention is given to the mass 20). M. C. Bellachioma, Beschleunigerpalaver, 14 September 2006.
The NEG characterization: film morphology Scanning Electron Microscopy – Energy Dispersive X-ray spectroscopy M. C. Bellachioma, Beschleunigerpalaver, 14 September 2006.
The NEG characterization: chemical composition Scanning Electron Microscopy – Energy Dispersive X-ray spectroscopy M. C. Bellachioma, Beschleunigerpalaver, 14 September Region of lowest activation temperature (180°C-24hrs) Well crystallised structure (grain size ≥ 100 nm) Nanocrystalline (3÷5 nm grain size) structure as confirmed by TEM
The NEG characterization: chemical composition Scanning Electron Microscopy – Energy Dispersive X-ray spectroscopy M. C. Bellachioma, Beschleunigerpalaver, 14 September Region of lowest activation temperature (180°C-24hrs) [At. %]TiVZr Dipole S06 MU1 30,54524,5 Dipole S06 MU2 31,8846,9221,19 Quadrupole S05 QS 1/2 30,4444,1824,43 EDX Results
The NEG characterization: activation properties M. C. Bellachioma, Beschleunigerpalaver, 14 September The produced non evaporable getters show good activation properties X-ray Photoelectron Spectroscopy
The NEG characterization: pumping speed M. C. Bellachioma, Beschleunigerpalaver, 14 September o How the produced coated chambers will perform in the SIS ?
The NEG characterization: pumping speed M. C. Bellachioma, Beschleunigerpalaver, 14 September Pumping speed is an important property of non evaporable getters and it is normally studied (for short pipes) by means of the Fischer-Mommsen dome TMP H2H2 CO Ar Standard dome NEG coated vacuum chamber L 2R o How the produced coated chambers will perform in the SIS ? P1 P2 L/R =10
The NEG characterization: sticking coefficient M. C. Bellachioma, Beschleunigerpalaver, 14 September For L/R as high as 50, H 2 transmission measurements should be preferred to the pumping speed measurements. NEG coated vacuum chamber TMP H2H2 L P1P1 P2P2
The NEG characterization: sticking coefficient M. C. Bellachioma, Beschleunigerpalaver, 14 September For L/R as high as 50, H 2 transmission measurements should be preferred to the pumping speed measurements. A complete MC simulation of the system is necessary to evaluate the P 1 /P 2 =f (sticking) relation. Whenever: P 1 is not different from the pressure at the entrance of vacuum chamber the molecular distribution is maxwellian at the entrance simple relations can be obtained by using the tabulated elementary probability t, b and s. NEG coated vacuum chamber TMP H2H2 L P1P1 P2P2
The NEG characterization: sticking coefficient M. C. Bellachioma, Beschleunigerpalaver, 14 September Parameters for the MC:
The NEG characterization: sticking coefficient M. C. Bellachioma, Beschleunigerpalaver, 14 September t transmission b backscattering s capture Elementary molecular probability t s b b + t + s = 1 Parameters for the MC: For a known sticking
The NEG characterization: sticking coefficient M. C. Bellachioma, Beschleunigerpalaver, 14 September t transmission b backscattering s capture Elementary molecular probability t s b b + t + s = 1 Parameters for the MC: For a known sticking H 2 Sticking probability measured for a coated dipole chamber after activation at 200°C (4 hrs) corresponding H 2 pumping speed: 0,4 l s -1 cm -2 CO Due to the system resolution, it was not possible to measure sticking factor for CO.
Sector S05/S06: actual situation… M. C. Bellachioma, Beschleunigerpalaver, 14 September At the end of July the quadrupole and dipoles chambers were coated and characterised…. 2.5m DN 200 DN 150 2m..pushed by the promising results we decided to modified the dipole coating facility to coat 2 additional straight pipes for the sector S05/S06
The SIS chambers: assembling M. C. Bellachioma, Beschleunigerpalaver, 14 September The assembly of the coated chambers in the sector S05/06 has been carried out at the beginning of September…. …and the activation of the NEG is foreseen during the week 39
What do we expect for one coated sector? M. C. Bellachioma, Beschleunigerpalaver, 14 September Increase of the beam lifetime Better base pressure Ageing of the NEG film P.Chiggiato et al.
Conclusions M. C. Bellachioma, Beschleunigerpalaver, 14 September The coating system build at GSI allows to coat easily bended chambers. o The coating system build at GSI allows to coat easily bended chambers. o The coating of the first chambers for the SIS 18 upgrade has been successfully performed, as proofed by the surface analysis results. o The coating of the dipole and quadrupoles chambers of the remaining sectors of the SIS 18 is foreseen o The application of the ERDA technique to follow the NEG activation process is taken into consideration. o A LabVieW program has been developed to control the bakeout and the NEG activation: the heating cycle will be automatically stopped if leaks occur K.Welzel
Acknowledgements Hartmut Reich-Sprenger, Jörg Kurdal, Holger Kollmus, Markus Bender, Andreas Krämer, Josè Cavaco, Dietrich Schäfer, Graziano Savino, Knut Welzel and Ludwig Heyl Special thanks to: Sergio Calatroni, Vladimir Rouzinov, Paolo Chiggiato and Cristoforo Benvenuti Paolo Chiggiato and Cristoforo Benvenuti for support in design and commissioning of the sputtering system and for the useful discussions for training and technical assistance M. C. Bellachioma, Beschleunigerpalaver, 14 September 2006.