Superconducting Undulator (SCU) Development at ANL Efim Gluskin on behalf of the APS/ANL team Superconducting Undulator R&D Review Jan. 31, 2014

Superconducting Undulator (SCU)Development at ANL

Efim Gluskin on behalf of the APS/ANL team

Superconducting Undulator R&D Review

Jan. 31, 2014

SCU R&D Review, Jan. 31, 2014

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Outline

• Developments of the APS superconducting undulator • SCU design and performance

- cryogenic design and performance- magnetic measurements and SCU performance- integration at the APS storage ring- reliability and spectral performance

• Future developments• R&D for the LCLS-II SCU prototype


Development of SCU at the APS

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Activity Years

A proposal of the helical SCU for the LCLS 1999

Development of the APS SCU concept 2000-2002

R&D on SCU in collaborations withLBNL and NHFML

2002-2008

R&D on SCU0 in collaborations withFNAL and UW-Madison

2008-2009

Design (in the collaboration with the BINP) and manufacture of SCU0

2009-2012

SCU0 installed into the APS storage ring December 2012

SCU0 is in routine user operation Since February 2013


SCU performance comparison

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Brightness Tuning Curves (SCUs1.6 cm vs. UA 3.3 cm vs. Revolver U2.3 cm & U2.5 cm)

Tuning curves for odd harmonics of the SCU and the “Advanced SCU” (ASCU) versus planar permanent magnet hybrid undulators for 150 mA beam current.

The SCU 1.6 cm surpasses the U2.5 cm by a factor of ~ 5.3 at 60 keV and ~ 10 at 100 keV. The tuning range for the ASCU assumes a factor of two enhancement in the magnetic field compared to

today’s value – 9.0 keV can be reached in the first harmonic instead of 18.6 keV.


First SC undulators for the APS

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APS superconducting undulator specifications

Test Undulator SCU0

Prototype UndulatorSCU1

Goal - Check design concept;- Study SCU behavior in SR

- Increase magnetic length

Photon energy at 1st harmonic

20-25 keV 12-25 keV

Undulator period 16 mm 18 mm

Magnetic gap 9.5 mm 9.5 mm

Magnetic length 0.330 m 1.140 m

Cryostat length 2.063 m 2.063 m

Beam stay-clear dimensions

7.0 mm vertical × 36 mm horizontal

7.0 mm vertical × 36 mm horizontal

Superconductor NbTi NbTi

SCU0 and SCU1 spectral tuning curves


Main milestones of the ANL part of the project

Design of the NbTi undulator magnetDesign of the cryostat for both 1.5 m undulatorsDesign of the vacuum systemProcurement of undulator cores, cryostat, cryocoolers, vacuum componentsAssembly and test of cryogenic and vacuum systems for NbTi undulatorMagnetic measurements of the NbTi undulatorAssembly, test and magnetic measurements of the Nb3Sn undulator

Total duration of the project: 18 months


Superconducting planar undulator topology

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Current directions in a planar undulator Planar undulator winding scheme

Magnetic structure layout

On-axis field in a planar undulator

• • +

• + • +

Period

• + • + • + •

• + • + • + •

+

Current direction in coil

e-

coil pole

Cooling tube

Beam chamber


SCU0 Assembly

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SCU0 being assembled in the new facility

• SCU0 was assembled at the APS in a new SCU facility

• Several sub-systems were first assembled including cold mass and current lead blocks

• Current lead assemblies were tested in a dedicated cryostat before installation into the SCU0 cryostat

• LHe tank with He circuits were leak checked

• Several fit tests were done• SCU0 assembly was

completed in May 2012

Fully assembled cold mass Cold mass and current lead assemblies fit test

Winding SCU coils up to 2.5 m long

Vacuum epoxy impregnation

Cryogenic and magnetic Testing

2 m cryostat

4 m cryostat

Curing Oven

SCU magnetic measurement system


SCU0 cryostat

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Cryostat vacuum vessel

He fill/vent turret

Cryocooler

Current leads

Cryocooler

Cryocooler

Vacuum pumpCryocooler

Beam chamber flange


SCU0 design

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LHe vessel

SC magnet He fill/vent turret

20 K radiation shield

60 K radiation shield

Beam chamber

Beam chamberthermal link to cryocooler

LHe piping

SCU0 Design Conceptual Points:• Cooling power is provided by four

cryocoolers• Beam chamber is thermally

insulated from superconducting coils and is kept at 12-20 K

• Superconducting coils are indirectly cooled by LHe flowing through the channels inside the coil cores

• LHe is contained in a 100-liter buffer tank which with the LHe piping and the cores makes a closed circuit cooled by two cryocoolers

• Two other cryocoolers are used to cool the beam chamber that is heated by the electron beam

SCU0 structure


SCU cold mass

Cold mass base frame

LHe vessel(StSteel/Cu bimetal )

Cu bar

Flexible Cu braids

Flexible Cu braids

He recondenser flange

SC magnet

Beam chamber


SCU0 cryo-performance

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The measured temperatures in the SCU0 cryostat at beam current of 100 mA (24 bunches), SCU0 magnet is off.

• Designed for operation at 500 A, SCU0 operates reliably at 650 A-680 A.

• The magnet cores remain at 4 K even with 16 W of beam power on the beam chamber

• No loss of He was observed in the period

of 12-month


SCU0 Cold Test – Cryogenic Performance: Cool down

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• A design concept of cooling the undulator down with compact cryocoolers has been confirmed. The system achieved cool-down during a day, using cryocooler power alone

The temperatures of the 4-K cryocoolers during initial cool-down of SCU0. The cryocoolers are 2-stage devices, with the 1st stage providing shield cooling and the 2nd stage cooling the liquid helium reservoir and superconducting magnet.


SCU magnetic measurement system design: Mechanical overview

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• One 3.5 m travel linear stage• Three ±1 cm travel transverse linear stages• Three manual vertical stages• Two rotary stages• Warm Ti tubing installed inside cold Al beam

chamber as guide for carbon fiber Hall probe assembly


Undulator Parameters

SCUO

LCLS-II SCU prototype

Magnet gap, mm 9.5 7.5

Vacuum chamber OD, mm 8.7 6.9

Vacuum chamber ID, mm 7.2 5.7

Ti tube OD, mm 6.35 5.0

Ti tube ID, mm 5.35 4.0

Hall Probe holder OD, mm 3.8 3.0

- Estimated heat load on cold beam chamber in this configuration is 1 W. - The beam chamber is cooled by two cryocoolers with cooling capacity of 40 W @ 20 K.

Cold (20K) Al beam chamber

Warm (~300K) carbon fiber tube holding Hall probe /coils

Warm (~300K) Ti guiding tube

Warm guiding tube approach


SCU magnet measurement system

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SCU horizontal measurement system was built at the APS. The concept is based on a warm-bore system developed at the Budker Nuclear Physics Institute for superconducting wigglers.The measurement system includes- Scanning Hall probe:

- Three-sensor rotatable Hall probe- Stretched wire coils:

- Rectangular, delta and figure-8 coils.Longitudinal stage linear travel : 3.5 m; positioning accuracy: 1 micron.Transverse stage linear travel: 1.0 cm.


SCU magnetic measurement Hall sensor assembly

Three Arepoc Hall sensors and one temperature sensor mounted to a ceramic holder which is then installed in a carbon fiber tube

Two sensors measure By above and below the mid-plane separated by ~1mm.

Third sensor measures Bx.

The assembly was calibrated from room to LHe temperature.

By1

Bx

3.8 mm OD29 mm length

By2


SCU0 magnetic measurement resultsHall probe data, trajectory and phase errors

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Trajectory

Phase errors 0.73 deg rms

No magnetic tuning


Calculated SCU0 peak field versus gap

4 5 6 7 8 9 10 11 120

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Planar NbTi SCU field vs. Magnetic gap(period = 16 mm)

PredictionSCU0 measured

Magnetic gap, mm

Peak

fiel

d, T


SCU0 on the APS storage ringSCU0 design, fabrication, magnetic measurements, testing: 2010-2012SCU0 installed: December 2012.Completed detailed commissioning plan during extended machine startup: January 2013 (~130 hr).SCU0 released for User operation: January 29, 2013

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Chamber alignment

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sensor 0 1

2 3 4 5 6

7 8 core

• Chamber alignment critical to protect SCU0 from excessive beam-induced heat loads.

• Alignment corrected for cool-down.

• Beam-based alignment using ID steering and ΔT, giving 100-μm accuracy.

• Alignment is stable over time.


Thermal analysis of beam-induced heat load

Analytical image-current heat load modeled using ANSYS.

Modeled chamber temperatures are within 10% of the measured temperatures.

Results are very satisfying, in light of 2-to-10-fold underestimated heat loads at ESRF, MAX (in-vac).

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sensor 0 1

2 3 4 5 6

7 8 core


Predicted vs. Measured chamber temps & power

Bunch mode

Calculated power *

(W)

Power from

measured T (W)

Predicted T (K)

Measured T (K)

Total RW heat load

(W)

Total 10-K heat load (W)

100 mA

24 3.8 3.3 13.6 12.8 16.0 14.3

324 0.5 0.7 7.9 8.3 2.0 3.4

hybrid 2.7 2.7 11.8 11.9 11.1 11.5

150 mA

24 7.3 ― 18.2 ― 30.1 ―

324 1.2 ― 9.2 ― 4.6 ―

chamber heater calibration thermal model

Added Al and both SS sectionsAl length 1.33 m

* Image-current heat load only; does not include 0.25 W synchrotron radiation heat load.

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Next SCUs for APS Upgrade

The APS Upgrade program includes two types of SCU:– SCU1: a 1-m long magnet in 2-m long SCU0-type cryostat – SCU2: a 2.0−2.3-m long magnet in 3-m long cryostat

Currently the SCU1 is under construction and planned for the installation on the APS ring in December 2014

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Main milestones of the ANL part of the project

Design of the NbTi undulator magnetDesign of the cryostat for both 1.5 m undulatorsDesign of the vacuum systemProcurement of undulator cores, cryostat, cryocoolers, vacuum componentsAssembly and test of cryogenic and vacuum systems for NbTi undulatorMagnetic measurements of the NbTi undulatorAssembly, test and magnetic measurements of the Nb3Sn undulator

Total duration of the project: 18 months


Schedule of the ANL part of the project


Cost of the ANL part of the project

Cost Level 02 Task Task 1 Task 2 Task 3 Non_Labor Labor Grand Total

SCU Prototype Schedule

SCU Prototype Undulator Specifications $14,594 $14,594

Magnet: $224,000 $304,995 $528,995 Cryostat: $896,000 $199,477 $1,095,477 Undulator Assembly $191,506 $191,506 Undulator Tests $137,776 $137,776 Undulator Total $1,120,000 $848,348 $1,968,348 Measurement System Specifications $28,982 $28,982 Conceptual Design $62,794 $62,794 Conceptual Design Review $39,448 $39,448 Detailed Design $65,557 $65,557 Detailed Design Review $42,787 $42,787

Measurement System Material Procurements $56,000 $56,000

Fabrication $64,266 $64,266 Tests $25,744 $25,744 Measurement System Total $56,000 $329,580 $385,580Grand Total $1,176,000 $1,177,928 $2,353,928


Summary

APS has developed, implemented and extensively tested robust cryogenic design for a planar SCU. The design employs closed loop LHe system.APS has developed and implemented magnetic measurement system that permits to characterize SCUs with the state-of-the-art accuracy and reproducibility.APS has successfully integrated SCU magnet, vacuum system and cryostat in the APS storage ring.SCUO has demonstrated superb operational record through one year of user operationsDeveloped SCU technology is ready to be applied for the future generation of radiation sources

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Back up slides


Hall probe data, vertical field and 1st field integral

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<Typical By field with Main coil current of 500A and correction coil current of 51.7A

1st field integral of above data>


SCU0 and Undulator A at the APS Sector 6

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SCU0 cryomodule has been installed in the downstream end of 6-ID on December 2012


Mechanical vibrationCryocooler vibrations do not adversely affect the beam motion.Vibration measured at three locations:

1. Beam chamber, 40 cm upstream of SCU0

2. Vacuum vessel, beam height

3. Support girder base (not shown)

Results for beam chamber shown at right.

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1 2

3

Cryocoolers off 0.38Cryocoolers on 0.68

Cryocoolers off 0.06Cryocoolers on 0.57

Integrated power density (μm rms),from 2 Hz to 100 Hz

Amplitude at 8.375 Hz (mm rms)


Thermal sensors map, SCU0 chamber

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6-ID SCU0

SCU0 temperatures monitored in the lab

Transition temperatures monitored in the ring (100 mA)


Beam-based alignment of SCU0 chamber using thermal sensors

Net resistive wall heating increases when the beam is not centered in the chamber.This can be used to find the vertical center of the chamber.

Radiation from the upstream bending magnet can potentially strike the cold chamber.BPMs at the dipole are used to steer the beam and minimize the temp.**Beam steering in the dipole also shows a vertical chamber displacement, consistent with the ID beam steering.

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First integral of the vertical field during a quench.

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Impact of SCU0 on beam operation

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First field integral measured with beam– Variation in first field integral was

inferred from effort of nearby steering correctors.

– Field integrals agree reasonably well with magnetic measurements in stand-alone tests.

Effect of quench on beam– Beam motion is small, even without

fast orbit feedback running, as in this example.

– Quench does not cause loss of beam– Beam position limit detectors were

not triggered.


Quenches

Quench event induced by sudden loss of 20 mA of the stored beam

Magnet temperatures were recovered quickly(2-3 min).

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Device has quenched during unintentional beam dumps. Procedures to mitigate these quenches are under investigation. Device is powered down prior to planned beam dumps.With the exception of beam dumps, the device quenched only twice in 8 months of user operations, operating above its 500-A design current. Stored beam was not lost, and total SCU0 downtime was < 1 hr.


SCU0 X-ray performance

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At 85 keV, the 0.34-m-long SCU0 produced ~45% higher photon flux than the 2.3-m-long U33.

Photon flux comparisons at 85 keV. Main: Simulated and measured SCU0 photon flux . Inset: Measured photon flux for in-line U33.

Documents

Superconducting Undulator (SCU) Development at ANL Efim Gluskin on behalf of the APS/ANL team Superconducting Undulator R&D Review Jan. 31, 2014