Preliminary Design Review Prepared by Robert Chave Robert Chave Applied Physics Inc.

1. Robust, Low Cost Cryo-coolerGoniometer for ARCSusing available, commercial grade, instrument components Preliminary Design Review Prepared by Robert Chave Robert Chave Applied Physics Inc. Altadena, California robert@chave.net 626-622-8562 Cryo-Cooler Goniometer for ARCS

2. Design Approach • A design which permits a range of options for sample mounting, and leaves opportunity for future modification for presently unspecified needs • Selection and placement of materials so as to avoid signal to noise reduction through scattering or a radioactive waste problem • Maximal use of off-the-shelf, or build-to-existing print major components to reduce cost both of primary build and availability of spares • Separate motion controller, independent from data computer for increased reliability, communicating with data computer through IEEE488 • Integrated system of motion controller, stepper drivers, motors, software and cables from an “all in one box” vendor of motion control technology Cryo-Cooler Goniometer for ARCS

3. Requirements / Goals Cryo-Cooler Goniometer for ARCS

4. Design Trade Studies • Basic Configuration Trade Study • Cooler on center, mechanical & thermal paths combined, single large built-to-user-specification, seal-bearing unit. • Cooler off-center, mechanical & thermal paths separate, standard seal-bearing unit, located on instrument centerline. • Cooler on center, mechanical & thermal paths, separate, main bearing on center & in vacuum, smaller standard seal. ☼ Cryo-Cooler Goniometer for ARCS

5. Configuration Trade Study Cryo-Cooler Goniometer for ARCS

6. Design Trade Studies Thermal Rotary Joint Trade Study Slip joint Conduction through mechanical flexure joint Thermal strap of fully annealed, three thousand strand, thin-strand, copper Litz wire. ☼ Vacuum Condensable Materials Reduction Trade Study Motors in and out of vacuum Ferroseal vs O-rings Lubricants, BraygreaseTM and DichroniteTM Cryo-Cooler Goniometer for ARCS

7. Cryo-cooler Goniometer for ARCS stepper motor NEMA23, 2 stack APD Sumitomo Cooler, 2 stage, 80 W max Worm drive,180:1 ratio, no back-lash stepper motor NEMA17, vacuum type harmonic drive, vacuum type ferrofluidic seal video camera drag link, w/ DelrinTM rod end bearings thin section, KaydonTM bearing assemblies thin section isolation tube, G10 or SS radiation shield flexible Litz wire thin wall SS axle sample mounting plate, aluminum thin section bearings Cryo-Cooler Goniometer for ARCS

8. ARCS Goniometer & Vacuum Jacket Cryo-Cooler Goniometer for ARCS

9. Design Trade Studies • Thermal Isolation Performance Trade Study • SS down tube • G10 down tube • Vibration Susceptibility Trades Study • Fundamental Frequencies • Brace approach Cryo-Cooler Goniometer for ARCS

10. Thermal Modeling • Isolation Links • Sources • Heat capacity of structure during cool down • Radiation (small compared with above) • Sinks • Cooler • Top plate System Sensitivities: The number and preparation of thermal joints drives cool down times, and lowest sample temperature attainable more strongly than other system parameters Cryo-Cooler Goniometer for ARCS

11. Cryocooler & Thermal Isolation Structure APD Sumitomo Cooler, 2 stage, 80 W maximum thin section isolation tube, G10 or SS radiation shield tubular SS axle flexible Litz wire sample mounting plate, aluminum thin section bearings Cryo-Cooler Goniometer for ARCS

12. Cooler Power APD 408S vs Cryotiger • SHI-APD 408 S • two stage • 80 Watts initial • final sample temp of 10 K • $ 27,800 • IGC-CryoTiger • 1 hour to 100 K • 10 Watts initial • final sample temp of 77 K • $ 8,655 each unit Cryo-Cooler Goniometer for ARCS

13. Cooler Performance & Conductor Performance cooler power conductivity integral for copper Specific Heat of Copper image credit: Cooner Wire Cryo-Cooler Goniometer for ARCS

14. Resistance of Thermal & Structural Elements • the number of mechanical joints between source and sink and their state of preparation is an influential design parameter • rougher surfaces are sometimes more effective than smooth ones • indium gaskets desirable on conductive joints Cryo-Cooler Goniometer for ARCS

15. Isolation System – Steady State Temperatures Down Tube G10 Down Tube G10 Bearing Spokes Sample Litz Wire Litz Wire Spokes Sample Bearings Cryo-Cooler Goniometer for ARCS

16. Cold End Thermal Isolation System • Spoke Properties • maximum heat flow ~ 550 mW • heat flow steady state < 50 mW • commercial product • titanium or stainless • low cost, high stiffness, readily available Cryo-Cooler Goniometer for ARCS

17. Mechanical Properties of Spokes Fundamental freq: ~ 2 kHz Factor of Safety: 10.5 Nom. Load per Spoke: 50 lbs Diameter: 1.5 mm Cryo-Cooler Goniometer for ARCS

18. Drive Train, 2 Axes stationary APD cooler head stepper motor NEMA23, 2 stack, Compumotor harmonic drive, 30:1, zero back-lash Worm drive,180:1 ratio, zero back-lash stepper motor NEMA17, 2 stack, vacuum rated ferrofluidic seal drag link, w/ DelrinTM rod end bearings drag link, w/ DelrinTM rod end bearings thin section, KaydonTM bearing assemblies sample mounting plate Cryo-Cooler Goniometer for ARCS

19. Expected Accuracy for Drive Train Primary Axis Secondary Axis Cryo-Cooler Goniometer for ARCS

20. Harmonic Drive image credits: HD Systems Inc. Cryo-Cooler Goniometer for ARCS

21. Thermal & Motion Sensors & Limit Switches • Sensors • Hall effect for end of travel and home position sensing, in vacuum • Motor temperature for in-vacuum motor • End effector temperature sensing with Lake Shore silicon diodes • Control System Switch Configuration Hard (switch) stops and soft (programmed) stops, with hard stops normally never encountered • Hard stops are wired directly to individual axis drive electronics Peperol & Fuchs NBB 1.5 – 8 GM60 Cryo-Cooler Goniometer for ARCS

22. Motion Control Software • Test scripts in Python • Communication w/ Controller either by Ethernet, or serial cable • Controller software is "Motion Planner" TM by Compumotor • well characterized, large installed user base, well supported • Point to point motion and calibration routines • S-curve accelerations, to limit ringing in mechanical components, from acceleration and braking Cryo-Cooler Goniometer for ARCS

23. Block Diagram, Drive Components Cryo-Cooler Goniometer for ARCS

24. Video Camera Video Camera for Sample in Vacuum Monitoring COHU Camera, to special performance specification for LLNL vacuum & radiation rated production run of 1000 for LLNL reduces price COHU 2600 b/w camera Cryo-Cooler Goniometer for ARCS

25. Preventing Binding During Insertion Cryo-Cooler Goniometer for ARCS

26. Virtual Leak Attenuation & Pump Down Speed • Methods Employed: Fastener holes and tapped holes drilled through to back side of part, such that these vent freely Use of center vented fasteners where back side vent ports are not practical No enclosed volumes & easy vacuum conductance from partially enclosed volumes Vapor degreasing, plus solvent cleaning to remove vacuum condensible material Cryo-Cooler Goniometer for ARCS

27. Instrument Case, Storage & Transfer • rapid instrument insertion • rapid instrument lock down • device cleanliness retained • fork lift o.k. • 3’ x 3’ x 3¼’ h Cryo-Cooler Goniometer for ARCS

28. References Papers Gimbal Mechanism For Cryogenic Alignment Of 1 Meter Diameter Optics, R. G. Chave, A. E. Nash, J. Hardy, SPIE Proceedings, 40th Annual Meeting, 1995 Handbook on Materials for Superconducting Machinery, ARPA order No. 2569, Program Code 4D10, Contract No. CST-8303, Cryogenics Division, NIST, 1977 Thermal Boundary Resistance of Mechanical Contacts Between Solids at Sub-Ambient Temperatures, E. Gmelin, M. Asen-Palmer, M. Reuther and R. Villar, Review Article, Journal of Physics D: Applied Physics 32 R19-R43, 1999. Texts Cryogenic Process Engineering, Timmerhaus & Flynn, Plenum Press, International Cryogenics Monograph Series, 1989 Experimental Techniques in Condensed Matter Physics at Low Temperatures, Richardson & Smith, Addison Wesley, 2nd Edition1998 Matter and Methods at Low Temperatures, F. Pobell, Springer Verlag 2nd Edition 1996 Cryo-Cooler Goniometer for ARCS

29. Budget - Purchased Parts Cryo-Cooler Goniometer for ARCS

30. Budget – Cost to Complete Cryo-Cooler Goniometer for ARCS

31. Schedule to Completion Cryo-Cooler Goniometer for ARCS