# Presentation: 662821

## 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
- 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*

## List of NSLS-II IDs

## Improving the rms phase error from 3.0° to 2.0° changes the relative intensities by 86% -> 98% for harmonic 7 ( = 12% points), 81% -> 96% for harmonic 9 ( = 15% points), and 75% -> 93% for harmonic 11 ( = 18% points).

***RMS Phase Errors***

**Roger Dejus**

## 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

## History of Mini-Gap Undulators at the NSLS

- Currently Installed

**Proposed**

## X-25 MGU Installed in the NSLS X-Ray Ring

## Direct Gap Measurement by Keyence LS-7030

- Measurement accuracy of ±2m and repeatability of ±0.15m

**Emitter**

**Detector**

**Upper Array**

**Lower Array**

## Direct Gap Measurement at Micron Resolutions

- Keyence gap readings track with post temperatures

**Upstream Gap**

**Post temperatures**

**Downstream Gap**

**10 ********m**

**35C°**

**30C°**

**10 min**

## 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**

## 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

## Peak Field Profile Comparison

- Apple-II

- HiSOR

***Tracking studies are needed to determine the effect ***
***of dynamic aperture reduction due to these roll-offs.***

## 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

## Superconducting Wiggler

***Superconducting Wiggler***

- NSLS-I Three Mode SCW by Oxford
- 11 pole @ 3.0T (u=17.6cm, gvac=19.5mm)
- 5 pole @ 4.7T
- 1 pole @ 5.5T
*HTS version** will be investigated*

## Superconducting Undulator (NSLS proto type)

- APC-type NbTi expected to run at Je=2000A/mm2
- Cooling channel underneath the coils to ensure maximum cooling

- Beam tube with integral cooling by He gas > 4K

- (Ceramic) isolating spacer

- Low carbon steel yoke

- Bifilar SC winding APC-type NbTi with integral He gas cooling @ 4K

**Yoke: **
**1006 Steel**

**Embedded He  Gas Cooling Channel**

## Other Insertion Device R&Ds

- 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

- New (In-vacuum) Gap Separation Mechanism

- Inner** **cage

- S. Chouhan

- Superconducting EPU

## Summary

**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

**CPMU**
- Cold measurement and shimming are main remaining issues
- New material R&Ds for further enhancement of the performance

**SCU**
- Low temperature SCUs still require R&Ds
- HTS versions are promising candidates in the future

**DW**
- Design and cost issues only
- Possible candidate for new gap separation mechanism