Update of the vacuum system of the European X-ray free electron laser XFEL Sven Lederer (MVS) Lutz Lilje (MVS) Torsten Wohlenberg (MVS) DESY, HAMBURG OLAV III July 11-14, 2011 Oak Ridge, Tennessee How to edit the title slide Upper area: Title of your talk, max. 2 rows of the defined size (55 pt) Lower area (subtitle): Conference/meeting/workshop, location, date, your name and affiliation, max. 4 rows of the defined size (32 pt) Change the partner logos or add others in the last row.

Outline Outline Introduction Vacuum- & RF-requirements for the warm vacuum system Warm vacuum section & components Gun Injector Bunch compressors (BC1, BC2) Collimator Beam distribution Undulator chamber & Intersection Exit-window for the main dumps Summary and Outlook Before you start editing the slides of your talk change to the Master Slide view: Menu button “View”, Master, Slide Master: Edit the following 2 items in the 1st slide: 1) 1st row in the violet header: Delete the existent text and write the title of your talk into this text field 2) The 2 rows in the footer area: Delete the text and write the information regarding your talk (same as on the Title Slide) into this text field. If you want to use more partner logos position them left beside the DESY logo in the footer area Close Master View OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Introduction European X-ray free electron laser (XFEL) is a light source of the 4th generation. Comparable with LCLS in California and SACLA in Japan Spring-8 OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Introduction Location of the European XFEL: The 3.4-km-long X-ray laser will begin on the DESY site in Hamburg-Bahrenfeld and run mostly underground to the research site, south of the town of Schenefeld (Schleswig-Holstein). DOP, FHH, Landesbetrieb Geoinf. und Vermessung, LGV41-07-130//DOP, (c) LVermA S-H 2007, S OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Introduction Research examples: Deciphering the structure of biomolecules: Exploring the nanoworld in 3D: Filming chemical reactions: Observing small objects in strong fields: Investigating extreme states of matter: OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

XFEL- vacuum sections: Introduction XFEL- vacuum sections: 5 m Undulator Warm vacuum system at room temperature Cold vacuum system superconducting linear accelerator in TESLA-technologie OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Vacuum and RF requirements for the warm vacuum system Goal: Avoid effects that causes of significant beam losses or beam quality deterioration Pressure requirements beam loss from scattering on residual gas PCO=10-7m bar (Ptot=5·10-7 mbar), calculation 10 e- from each bunch negligible! Bremsstrahlung is small, mirrors! Emittance growth negligible as well Fast ion instability: ionized molecules interact with bunches along train, initial small offset is exponentially amplified along bunch train; for XFEL bunch distance of 200 ns only ion masses beyond M≈100 can be captured → no thread independent of pressure OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Vacuum and RF requirements for the warm vacuum system Caused by the short elctron bunch length, wake fields are a critical issue to the performance of the machine.To minimize the deterioration of the beam quality for each vacuum section requirements on… rms surface roughfness Oxide layer Relative permeability Maximal step at flange connections Maximal gap in longitudinal direction RF-shielding of bellows, valves and pump ports are specified in the „High level specifications for aligment and surface properties of vacuum components“ OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Vacuum and RF requirements for the warm vacuum system High Level Specifications for Alignment and Surface Properties of Vacuum Components, Available at EDMS D00000001914751. OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Gun & Injector : RF-gun copy of the prototype RF- gun”4” 1.5 cell L-band normal conducting Cu cavity. Tuning to the resonance frequency is done by controlling the cooling water temperature of 14 separated cooling channels Average pressure in the gun section p <1∗ 10 −10 mbar due to the photocathode & the accelerating module (high density of pumps 10 SIPs & 5 TSPs) RF-gun has to be particle free cleaned to ensure operation with high accelerating gradients and long RF-pulses High density of diagnostic components RF-gun, coupler solenoids & photocathode load-lock-system RF-gun 4 Double diagnostic cross OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Bunch compressors (BC1, BC2) Bunch compressors section particle free cleaned due to the accelerating modules Average pressure in the bunch compressor section: 1.8∗ 10 −8 mbar Pressure stage on both ends of each section to reduce the pressure in a short distance 1.5 m over two orders of magnitude due to the transitions to the cold vacuum Fast shutter Chicane 21m long TDS Pump vessel 4 TSPs Gate valve TSP 𝑒 − Slotted beam pipe 300l/s SIPs Gate valve Pressure stage 1.5m long, pressure reduction from 10 −8 mbar to 10 −10 mbar Inside of the pump vessel of the pressure stage Pressure profil along BC1 OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Bunch compressors (BC1, BC2) Girder concept: ( 8 girder in BC1& 12 girder in BC2) The beamline components of the girders will be assembly particle free in a clean room The connection of the girders in the tunnel will be done under local clean rooms Vertical bunch compressor chicane (design by BINP) brazing solution with Cu & stainless steel and flat seal flanges BC1 chicane Example for a BC1 girder Cross sections of the vacuum chamber OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Collimator: Collimator concept: Vacuum vessel with a vertical movable collimator inside Collimator itself will made in „sandwich“ technology: copper(in the front)/titanium (on the back) Manipulator for shifting Collimator with different holes diamter Vacuum vessel Colimator with vacuum vessel(design by BINP) Cooling tube OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Beam distribution Standard inner beam pipe diameter 40.5 mm Beam pipe material: Copper Cu-HCP (CW021A) tube or copper coated stainless steel (1.4435) tube Standard flange CFX50 (modified CF50 conflat flange) Particle cleanliness is in general not required (some exceptions) Required average pressure is 2∗ 10 −8 mbar (some exceptions) Simulated pressure profile along a standard transport line of 11 elements with 6.3 m distance between the SIPs (blue); same simulation but assuming malfunction of one SIP represented by red curve. OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Beam distribution: Some Details RF-noses with 0.2mm gap Flange 1 Flange 2 Conflat sealing Beam axis 𝑒 − Standard CFX50 flange connection Alignment tool for standard flange connections OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Beam distribution: Inline sputter ion pump Inline vacuum pump wich are directly mounted into the beam line without T-piece Symmetric arrangment of the magnets around the beam Tube No effect on the beam e.g. kick on the beam ! Integrated RF shielding Pumping speed measured corresponding to DIN 28429 Rough pump connection HV feedthrough Space for magnets Magnetic shielding (iron) Copper tube with pumping slits Vacuum CFX50 flange Magnetic stray field measurement OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Extruded aluminium profile with high tolerance for wall thickness & straightness A good survey and alignment concept are essential due to the small aperture of the beam pipe! Small aperture for the undulator chamber: VERTICAL 8.8 mm HORIZONTAL 15.0 mm Very high surface quality needed to minimize the wake fields losses Material with a high electrical conductivity Low surface roughness rms < 300 nm rms in beam direction (longitudinally) Thin oxide layer ≤ 5 nm Water cooling Two wire corrector (inner channels) Friction welding flanges transition SS/Al Cross section of the 5.5 m long Undulator chamber OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection The calculation of the vacuum chamber deforming due to its vacuum pressure: Requirement for the deforming: < 0.05 mm Chamber dimensions: height 9.6 mm wall thickness 0.4 mm (like sFLASH chamber) FEM analysis result: deforming 3.7·10-4 mm on each side → in line 3.7·10-4 mm M. Rüter M. Rüter OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection The calculation of the vacuum chamber deflection due to its dead weight: Requirement for the deflection: < 0.05 mm The distance of two chamber holder : 550 mm FEM analysis result: 0.034 mm → in line M. Rüter OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Support system for the Undulator vauum chamber Undulator vacuum chamber fixation and aligment OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Detail of the alignment system Proof of principle of this alignment concept was done at sFlash, and PETRAIII where the undulator gap could be closed to design value: sFlash 9 mm & PETRAIII 12.5 mm PETRAIII Horizontal adjustment Vertical adjustment Angular adjustment Undulator vacuum chamber sFLASH OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & intersection Surface roughness: Roughness: nearly 200 nm r.m.s. for untreated vacuum chamber Minimize the surface roughness with AFM (abrasive flow machinig) treatment by a factor of three AFM Extruded Profile roughness 100nm r.m.s. Roughness 27nm r.m.s. Mirrow like finish Surface of the aluminium before and after the AFM (abrasive flow machining) OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Oxide layer Oxide layer: nearly 10(Al-Oxid)+13(Al-Silikat) nm for untreated vacuum chamber Chemical cleaning: Aluminiumoxid 10nm 3,5nm Oxidlayer Aluminiumsilikat 13nm Oxide layer on the AFM polishing Aluminium before and after the chemical cleaning OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Wakefield`s calculations: That a roughness off 300 nm r.m.s. and an oxide layer of 5 nm are acceptable. (Martin Dohlus, Igor Zagorodnov (MPY)) Al or Cu coating inside is essential if the material choice is stainless steel ! With the exception of the Cavity-BPM ! RF-shielding of flanges, bellows and pump ports are essential. A good survey and alignment concept are essential due to the small aperture of the beam pipe! Pressure profile along 10 undulator segments where 1 SIP malfunctions (red), and normal operation for comparison (blue). OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Intersection details OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Absorber details For the spontaneous radiation of the SASE Undulators top view –large shadow angle horizontal taper from 15mm to 9 mm side view –small shadow angle, vertical from 8.8 mm to 8 mm front view Transition from elliptical beam pipe (v. 8.8 mm x h. 15 mm) to the round beam pipe 10 mm. The calculation of photo desorption through the tapered absorber done by Ulrich Hahn (HASYLAB) and Horst Schulte-Schrepping (HASYLAB). → Result: the power lost at the last absorber is 51 W at 17.5 GeV and 30k bunches OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Pump cross details: 6 Pump slits: 2.6 mm wide, 30 mm long Roughness of the beam pipe ≤ 300 nm r.ms. Beam tube inside coated with Cu or Al oxide layer ≤ 5 nm As an example: Company Dockweiler: Ultron® seamless tube 316l(1.4435) electro polish ≤ 162 r.m.s. Picture taken from Company Dockweiler: Ultron® tube electro polish Cross section of the pump cross OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Flange connection: UHV flange connection with UHV- RF-flat seal to reduce wakefields effects. Four connection at each intersection A very good and reliably RF- transition! Flange connection are pinned to minimize the mismatch < 0.1 mm on the Undulator side & flange connection with male and female concept with small tolerance to minimize the mismatch on the cavity BPM side Flange design for the link to the Undulator vacuum chamber Flange design for the link to the cavity BPM (Female flange) Elliptical RF-UHV-connection with a step in the aperture of 0.05 mm (vertical 8.85 mm, horizontal 15.05 mm) The transition from round to elliptical aperture placed at the UHV-flange Round RF-UHV-connection with a step in the aperture of 0.05 mm (Ø 10.05 mm) OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Undulator chamber & Intersection Bellow details: Needed for assembling the components Needed for length compensation Needed to provide decoupling of transversal forces into the BPM region Longitudinal off-set ± 2 mm, 2 mm gab after installation Lateral off-set ± 0.1 mm after installation Simple bellow design from BINP OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Warm vacuum section & components Exit window for the main dumps Separation of the machine vacuum and the absorber vacuum Particle cleanness is not required We need a reliable design concept High reliably for the leak thightness Dismounting is difficult due to the high radioactive activation Copper Titanium foil (0.5 mm) for leak thightness Aluminium oxid ceramic (𝐴𝑙 2 𝑂 3 ) for beam diagnostic Graphite Water cooling Exit window in braze technology , diameter 200 mm OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Several requirements to be fulfilled Summary & Outlook Several requirements to be fulfilled Baseline pressure not too ambitious in the warm sections of the XFEL, but: Particle cleanliness required in the cold part and warm parts adjacent to the cold linac High beam quality requires several solutions Surface quality in chambers with small diameter (undulators) Alignment Steps between flanges Etc. Project is progressing well! OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg

Thank you for your attention! OLAV III July 11-14, 2011 Oak Ridge, Tennessee Update of the vacuum system of the European X-ray free electron laser Torsten Wohlenberg MVS DESY, Hamburg