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
Roger Dejus
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).

5. CPMU Cryo-Permanent Magnet Undulator (Hara, et. al., 2004)
Simple Concept: NdFeB has a negative thermal coefficient of remanent field (Br) [-0.1 % / and of intrinsic coercivity (Hcj) [-0.5% / ]
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
Apple-II
HiSOR
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 3.0T (lu=17.6cm, gvac=19.5mm)
5 4.7T
1 5.5T
HTS version will be investigated

15. Superconducting Undulator (NSLS proto type)
Bifilar SC winding APC-type NbTi with integral He gas 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
Inner cage
S. Chouhan
High-Temperature Superconducting Undulator
Cryocooler capacity increases drastically with higher temperature (ex. 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

17. Summary CPMU EPU DW SCW SCU
Cold measurement and shimming are main remaining issues
New material R&Ds for further enhancement of the performance
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
SCW
OK for LTS
Higher field version / HTS version will be investigated
SCU
Low temperature SCUs still require R&Ds
HTS versions are promising candidates in the future