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NSLS-II Insertion Devices

NSLS-II Insertion Devices. Toshi Tanabe George Rakowsky, John Skaritka, Steve Hulbert, Susila Ramamoothy NSLS/BNL NSLS-II Accelerator Systems Advisory Committee 2006/10/9-11. Outline. List of NSLS-II insertion devices (baseline + options) Comment on Phase Errors

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NSLS-II Insertion Devices

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  1. NSLS-II Insertion Devices Toshi Tanabe George Rakowsky, John Skaritka, Steve Hulbert, Susila Ramamoothy NSLS/BNL NSLS-II Accelerator Systems Advisory Committee 2006/10/9-11

  2. Outline • List of NSLS-II insertion devices (baseline + options) • Comment on Phase Errors • Cryo-Permanent Magnet Undulator (CPMU) for hard X-rays • Cold Measurement Issues • New magnet and pole materials • Elliptically Polarized Undulator (EPU) • Apple-II v.s. HiSOR (SPring-8) Design • Permanent Magnet Damping Wiggler • Superconducting Wiggler (SCW) • Superconducting Undulator (SCU) • Conventional, VPU and HTS versions • No QPU, Figure-8, Revolver options are discussed

  3. List of NSLS-II IDs

  4. RMS Phase Errors • Improving the rms phase error from 3.0° to 2.0° changes the relative intensities by 86% -> 98% for harmonic 7 (D = 12% points), 81% -> 96% for harmonic 9 (D = 15% points), and 75% -> 93% for harmonic 11 (D = 18% points). Roger Dejus

  5. CPMU • Cryo-Permanent Magnet Undulator (Hara, et. al., 2004) • Simple Concept: NdFeB has a negative thermal coefficient of remanent field (Br) [-0.1 % / K@20ºC], and of intrinsic coercivity (Hcj) [-0.5% / K@20ºC ] • Higher field and higher radiation damage resistance simply by cooling the magnet array in lower temperature (~150K) • Remaining Issues • Cold measurement system • Cold shimming technique if required • New Material R&D • PrFeB magnet and Dy pole combination for operation at lower temperature than 150K

  6. History of Mini-Gap Undulators at the NSLS Currently Installed Proposed

  7. X-25 MGU Installed in the NSLS X-Ray Ring

  8. Direct Gap Measurement by Keyence LS-7030 Measurement accuracy of ±2mm and repeatability of ±0.15mm Upper Array Detector Emitter Lower Array

  9. Direct Gap Measurement at Micron Resolutions Keyence gap readings track with post temperatures 35C° 10 min Upstream Gap 10 mm Post temperatures Downstream Gap 30C°

  10. Cold Measurement System Cold In-Situ Field Measurement In-vacuum mapper with Hall probe. The postion accuracy is maintained by laser tracker and piezo controller. • In-vacuum streched / pulsed wire systems are also in consideration

  11. EPUs • Apple-II v.s. HiSOR EPU (eventually in-vacuum) • Apple-II : bigger tuning range, simpler structure • HiSOR EPU: easier shimming and more benign field profile • Better vacuum chamber design to reduce the radiation damage of permanent magnets maybe needed

  12. Peak Field Profile Comparison • HiSOR • Apple-II Tracking studies are needed to determine the effect of dynamic aperture reduction due to these roll-offs.

  13. MPW (1.8T / 15mm Gap) • Conventional Hybrid Design with Permendur Poles • Close to the limit with simple block structures • Reducing the gap with soft-iron poles will certainly reduce the cost

  14. Superconducting Wiggler • NSLS-I Three Mode SCW by Oxford • 11 pole @ 3.0T (lu=17.6cm, gvac=19.5mm) • 5 pole @ 4.7T • 1 pole @ 5.5T • HTS version will be investigated

  15. Superconducting Undulator (NSLS proto type) Bifilar SC winding APC-type NbTi with integral He gas cooling @ 4K • APC-type NbTi expected to run at Je=2000A/mm2 • Cooling channel underneath the coils to ensure maximum cooling (Ceramic) isolating spacer Beam tube with integral cooling by He gas > 4K Low carbon steel yoke Yoke: 1006 Steel Embedded He Gas Cooling Channel

  16. Other Insertion Device R&Ds • New (In-vacuum) Gap Separation Mechanism • Superconducting EPU • High-Temperature Superconducting Undulator • Cryocooler capacity increases drastically with higher temperature (ex. 300W@40K, 600W@77K by Cryomech, Inc.) • Splices do not create quench problem if cooled sufficiently • Quench propagation is on order of magnitude slower than LTS  Simpler and cheaper protection scheme Innercage S. Chouhan

  17. Summary • CPMU • Cold measurement and shimming are main remaining issues • New material R&Ds for further enhancement of the performance • SCW • OK for LTS • Higher field version / HTS version will be investigated • EPU • Apple-II or other structure to be determined after tracking study • Better vacuum chamber design to minimize radiation damage on magnets • In-vacuum EPU design will be a R&D subject • DW • Design and cost issues only • Possible candidate for new gap separation mechanism • SCU • Low temperature SCUs still require R&Ds • HTS versions are promising candidates in the future

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