Neutron Beam Extraction System Engineering Developments at ESS

1. Neutron Beam Extraction System Engineering Developments at ESS Daniel Lyngh1, Naja Dornonville de la Cour1, Lennart Åström1, Jarich Koning1, Bengt Jönsson1, Yannick Beßler2, Patrick Heldmann2, Christopher Hall2 , 1EuropeanSpallation Source ERIC, 2Forschungszentrum Jülich ICANS XXII - Chattanooga Tennessee Oct 17th 2019

2. Outline • Beam Extraction Design • Guide integration • Installation • Prototyping and Testing • Light Shutter System

3. In memory of our dear colleagues Reinhard Blum Anton Kohle

4. ESS Source to sample Neutron Beam Extraction System Nuclear Physics Institute + Monolith BEER NMX + C-SPEC BIFROST MIRACLES MAGIC T-REX ODIN HEIMDAL DREAM • Neutron beam extraction • Offers 42 double decker neutron beam ports • Allows neutron science instruments choose between viewing top or bottom moderator • First 15+1 instruments that are part of the Construction Project will view the top moderator • 26 non used available ports will be plugged awaiting instruments. LoKI VESPA FREIA SKADI ESTIA +

5. ESS Target Station • Moderators • Provisional locations of moderators above and beneath the target wheel, i.e. monolith centre • 1st MR plug exploits the upper space, offering: • Cold, 30 mm high, liquid H2 moderators, 17K. • Thermal, 30 mm high, H2O moderator, 300K. • Target • Rotating solid tungsten target: • 36 sectors, synchronized rotation of 23.3 rpm with the pulsed proton beam 14 Hz. • Mass, total 11 Ton, whereof 3 Ton of W. • Helium cooling of target material: • Mass flow 3 kg/s@11 Bar • Temperature inlet/outlet 40 °C/240 °C • Monolith Vessel and Port Tubes • Rough Vacuum: 1 mBar, 2 Bar (a) Design Pressure. • Ø5.5m filled with stainless steel shielding • Surrounded by another 2.7 m steel shielding • Diagnostics & instrumentation • Controlled and integrated commissioning and operation of the accelerator and target • Fluorescent coating of PBW and target front face • Optical paths, grid profile monitor, aperture monitor • Wheel monitoring including position, temperature, vibration, as well as internal structure • Target Safety System • Monitors target coolant flow, pressure and temperature, monolith pressure, & target wheel rotation • Prohibit beam on target if parameters are outside specified limits

6. Monolith Vessel • Monolith • In contrary to other facilities, ESS does not have heavy shutters to minimize the distance to the first pulse chopper system to extend the dynamical range at the instrument Proton Beam Neutron Beam Extraction Port Target Wheel Moderator & Reflector ProtonBeam Window

7. Beam Port Arrangement • 42x double decker beam ports @ 6m radius leads to very tight space constraints between the beam ports, limiting access and design of the beam port inserts as well as bunker layout of choppers etc. Division is 5.3/6.7°C to minimize beam line interference during installation and maintenance. • Lines for cooling the insert as well as to provide the atmosphere for the optical guide needs to penetrate the monolith pressure vessel at the port entrance location.

9. Double decker design “ESS Target Station #2” Top Bottom

10. Double decker design “ESS Target Station #2” Part of exchangeable Moderator & Reflector Plug Part of exchangeable Neutron Beam Port Insert Flightpath Top Moderator Possible Flightpath Bottom Moderator

11. Neutron Beam Extraction Path

12. Neutron Beam Extraction System Neutron Flight Path • Neutron Beam Port Insert: • Integrates 3 pieces of Copper Beam Guides that guides the beam from R2 to R5,5m • Maintains a protective atmosphere for the integrity of the guide (He@1Bar) • Cooled to maintain a temperature <60°C using water channels through the stainless steel chassis • Enables positioning of the Optical Assembly within 50𝞵m • 3.5 meters long, 70cm high, made out of a solid piece of low cobalt 316L forged piece of steel • Can fit optics looking at top or bottom moderator (or possibly both) • Light Shutter System • Positions Bridge Beam Guide that passes neutrons from NBOA to the instrument system, including chopper and guide system right outside the Monolith • Shuts beam path and blocks gamma with a ~45cm thick block hindering gamma radiation during bunker maintenance • Enables switching between multiple optical guides

13. Neutron Beam Port Insert and Optical Assemblies Optical guide customisation • Large, intricately machined piece made out of low cobalt (<0.05%) 316 stainless steel holding the Optical Assemblies • The main purpose being aligning and maintaining the Neutron Beam Optics Assemblies processed atmosphere while enabling fine alignment of the optics assemblies within it, 50µm. • All 16 instruments are unique and have their own insert/guide design • 14 out of 16 planned Inserts have integrated optics • The two remaining instruments have collimating voids Neutron Beam Optics Assembly Neutron Beam Port Insert

14. Neutron Beam Optic Assemblies Customisation and Integration • Differ in shape, size, curvature • Need customisation of NBPI for: • Cooling channels • Alignment feature access • Helium Atmosphere void • Atmosphere separating windows • Backfilling

15. Neutron Beam Port Insert Windows • Separates the helium atmosphere of the Optic Assembly from the Monolith Vessel vacuum • Customized sealing solution defined by ESS vacuum group • 1.5-2mm thick depending on Instrument geometry • Al 6061 T6 or Al 6061 T651 can be used • Gasket material Al1050-H24 • Windows are calculated for deflection and plastic strain due to NBOA atmosphere/Monolith Vessel atmosphere difference • Profile is small trapezoid milled into body and lid compressing gasket material • Same solution used for alignment features

16. Neutron Beam Port Inserts Insertion Tolerances Courtesy of Alan Takibayev

17. Neutron Beam Port Insert Installation Alignment • Beam Port Tube adjustment features are adjusted to a nominal ”perfect position” 5 DOF • Insert is rolled in and lands on defined surfaces FRONT BACK

18. Heat Analysis of NBPI C-SPEC Peak heat load vs Instrument position • Neutronic Heat Load Calculation • Highest Heat Load: C-SPEC • C-SPEC geometry is narrow and hard to cool • NSS requirement of keeping NBOA below 60 C • Chosen as instrument to verify calculations Courtesy of Alan Takibayev

19. Heat Analysis of NBPI Insert customized for C-SPEC 200 mm increased length & moved 50 mm to top 50 mm 200 mm original Modified water cooling max temp 71 C Original, max temp 77 C Temperature of NBPI body Modified water cooling max temp 57 C Original, max temp 64 C Temperature of NBOA geometry exceeding requirement of 60 C Courtesy of Jörg Wolters, FZJ

20. Neutron Beam Port Insert Optical guide cooling and protective atmosphere • The Neutron Beam Window that sits between the Neutron Beam Port Insert and the Bridge Beam Guide acts as a jumper to transfer fluid/gas into the unit in the vessel. • The Insert has deep hole drilled cooling lines that circulates water as cooling medium maintaining the insert and especially the Optical Guide at correct temperature (<60°C). Neutron Beam Window Seal Media Connector Insert Media Connector Outside

21. Bridge Beam Guide Light Shutter Frame • The Bridge Beam Guide sits between the Neutron Beam Window and the instrument guide providing optical guiding of the neutron beam from the insert to the first piece of bunker optical guide. • The Light Shutter System carries and positions the Bridge Beam Guide Optics with a precision of 50-500µm depending on dof. • Could enable switching between up to three optical guides. • Bridge Beam Guide Optics has an own vacuum environment and is uncooled. Bridge Beam Guide Bridge Beam Guide Vessel Neutron Beam Port Insert Neutron Beam Window

22. Prototyping and Testing Light Shutter System Light Shutter Frame • Verification of the design of the current concept for the Light Shutter System • Testing the function of: • Positioning of Gamma Beam Shutter • High precision positioning of Bridge Beam Guide Optical Assembly in 6 DOF • Handling Procedure • Required Forces • Deformation • Function of Shock Absorbers • Temperature and Vibration Gamma Beam Shutter NBW/Port Block Flange Mock-up Bridge Beam Guide Vertical Test Stand Frame Floor Filler Block MPS/PSS safety bar/switch Shock absorber

23. Neutron Beam Extraction System Bunker Area Handling NBPI Horizontal Handling via Bunker Light Shutter System Vertical Handling via Basement Insert Exchange Tool Basement

24. Prototyping and Testing Neutron Beam Port Insert • Verificationof the design of the Neutron Beam Port Insert • Testing the functionof: • Wheels/Rollers • Alignment and alignment features • Rails • Handling Procedure • RequiredForces • Functionof Installation Tool • Media connectorconcept • Temperature and Vibration • Deformation Neutron Beam Port Insert Prototype Horizontal Handling Test Stand Insert Installation Tool

25. Neutron Beam Port Guide Insert - Prototype • Main purpose of the NBPI prototype was to verify the manufacturability of the instrument void. • All instrument voidsareunique, LOKI was chosen for the prototypebecause it is the mostechallengingbeingverydeep and narrow • Manufacturingshowedthat the bottomsurface in the guide voidrequired a lotof hand finishing. Tolerancessubsequentlyrelaxed to allow for steppedmachining

26. Neutron Beam Port Guide Insert - prototype

27. Thank you!