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, 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

SCU R&D Review, Jan. 31, 2014 Development of SCU at the APS 3 ActivityYears A proposal of the helical SCU for the LCLS1999 Development of the APS SCU concept R&D on SCU in collaborations with LBNL and NHFML R&D on SCU0 in collaborations with FNAL and UW-Madison Design (in the collaboration with the BINP) and manufacture of SCU SCU0 installed into the APS storage ringDecember 2012 SCU0 is in routine user operationSince February 2013

SCU R&D Review, Jan. 31, 2014 SCU performance comparison 4 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.

SCU R&D Review, Jan. 31, 2014 First SC undulators for the APS 5 APS superconducting undulator specifications Test Undulator SCU0 Prototype Undulator SCU1 Goal- Check design concept; - Study SCU behavior in SR - Increase magnetic length Photon energy at 1 st harmonic keV12-25 keV Undulator period 16 mm18 mm Magnetic gap9.5 mm Magnetic length0.330 m1.140 m Cryostat length2.063 m Beam stay-clear dimensions 7.0 mm vertical × 36 mm horizontal SuperconductorNbTi SCU0 and SCU1 spectral tuning curves

SCU R&D Review, Jan. 31, 2014 Main milestones of the ANL part of the project Design of the NbTi undulator magnet Design of the cryostat for both 1.5 m undulators Design of the vacuum system Procurement of undulator cores, cryostat, cryocoolers, vacuum components Assembly and test of cryogenic and vacuum systems for NbTi undulator Magnetic measurements of the NbTi undulator Assembly, test and magnetic measurements of the Nb 3 Sn undulator Total duration of the project: 18 months

SCU R&D Review, Jan. 31, 2014 Superconducting planar undulator topology 7 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-e- coil pole Cooling tube Beam chamber

SCU R&D Review, Jan. 31, 2014 SCU0 Assembly 8 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 massCold 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

SCU R&D Review, Jan. 31, 2014 SCU0 cryostat 10 Cryostat vacuum vessel He fill/vent turret Cryocooler Current leads Cryocooler Vacuum pump Cryocooler Beam chamber flange

SCU R&D Review, Jan. 31, 2014 SCU0 design 11 LHe vessel SC magnet He fill/vent turret 20 K radiation shield 60 K radiation shield Beam chamber thermal 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 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 R&D Review, Jan. 31, 2014 SCU cold mass Cold mass base frame LHe vessel (StSteel/Cu bimetal ) Cu bar Flexible Cu braids He recondenser flange SC magnet Beam chamber

SCU R&D Review, Jan. 31, 2014 SCU0 cryo-performance 13 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

SCU R&D Review, Jan. 31, 2014 SCU0 Cold Test – Cryogenic Performance: Cool down 14 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 1 st stage providing shield cooling and the 2 nd stage cooling the liquid helium reservoir and superconducting magnet.

SCU R&D Review, Jan. 31, 2014 SCU magnetic measurement system design: Mechanical overview 15 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

SCU R&D Review, Jan. 31, 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 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 R&D Review, Jan. 31, 2014 SCU magnet measurement system 17 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 R&D Review, Jan. 31, 2014 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 B y above and below the mid-plane separated by ~1mm. Third sensor measures B x. The assembly was calibrated from room to LHe temperature. B y1 BxBx 3.8 mm OD 29 mm length B y2

SCU R&D Review, Jan. 31, 2014 SCU0 magnetic measurement results Hall probe data, trajectory and phase errors 19 Trajectory Phase errors 0.73 deg rms No magnetic tuning

SCU R&D Review, Jan. 31, 2014 Calculated SCU0 peak field versus gap

SCU R&D Review, Jan. 31, 2014 SCU0 on the APS storage ring SCU0 design, fabrication, magnetic measurements, testing: SCU0 installed: December Completed detailed commissioning plan during extended machine startup: January 2013 (~130 hr). SCU0 released for User operation: January 29,

SCU R&D Review, Jan. 31, 2014 Chamber alignment 22 sensor 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.

SCU R&D Review, Jan. 31, 2014 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). 23 sensor core

SCU R&D Review, Jan. 31, 2014 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 hybrid mA 247.3―18.2―30.1― ―9.2―4.6― chamber heater calibration thermal model Added Al and both SS sections Al length 1.33 m * Image-current heat load only; does not include 0.25 W synchrotron radiation heat load. 19

SCU R&D Review, Jan. 31, 2014 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

SCU R&D Review, Jan. 31, 2014 Main milestones of the ANL part of the project Design of the NbTi undulator magnet Design of the cryostat for both 1.5 m undulators Design of the vacuum system Procurement of undulator cores, cryostat, cryocoolers, vacuum components Assembly and test of cryogenic and vacuum systems for NbTi undulator Magnetic measurements of the NbTi undulator Assembly, test and magnetic measurements of the Nb 3 Sn undulator Total duration of the project: 18 months

SCU R&D Review, Jan. 31, 2014 Schedule of the ANL part of the project

SCU R&D Review, Jan. 31, 2014 Cost of the ANL part of the project Cost Level 02 TaskTask 1Task 2Task 3Non_LaborLaborGrand Total SCU Prototype Schedule SCU PrototypeUndulatorSpecifications $14,594 Magnet:$224,000$304,995$528,995 Cryostat:$896,000$199,477$1,095,477 Undulator Assembly $191,506 Undulator Tests $137,776 Undulator Total $1,120,000$848,348$1,968,348 Measurement SystemSpecifications $28,982 Conceptual Design $62,794 Conceptual Design Review $39,448 Detailed Design $65,557 Detailed Design Review $42,787 Measurement System Material Procurements$56,000 Fabrication $64,266 Tests $25,744 Measurement System Total$56,000$329,580$385,580 Grand Total $1,176,000$1,177,928$2,353,928

SCU R&D Review, Jan. 31, 2014 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 operations Developed SCU technology is ready to be applied for the future generation of radiation sources 29

SCU R&D Review, Jan. 31, 2014 Back up slides

SCU R&D Review, Jan. 31, 2014 Hall probe data, vertical field and 1 st field integral 31 <Typical B y field with Main coil current of 500A and correction coil current of 51.7A 1 st field integral of above data>

SCU R&D Review, Jan. 31, 2014 SCU0 and Undulator A at the APS Sector 6 32  SCU0 cryomodule has been installed in the downstream end of 6-ID on December 2012

SCU R&D Review, Jan. 31, 2014 Mechanical vibration Cryocooler 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 Cryocoolers off0.38 Cryocoolers on0.68 Cryocoolers off0.06 Cryocoolers on0.57 Integrated power density (μm rms), from 2 Hz to 100 Hz Amplitude at Hz (  m rms)

SCU R&D Review, Jan. 31, 2014 Thermal sensors map, SCU0 chamber 34 6-IDSCU0 SCU0 temperatures monitored in the lab Transition temperatures monitored in the ring (100 mA)

SCU R&D Review, Jan. 31, 2014 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. 35

SCU R&D Review, Jan. 31, 2014 First integral of the vertical field during a quench. 36

SCU R&D Review, Jan. 31, 2014 Impact of SCU0 on beam operation 37 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.

SCU R&D Review, Jan. 31, 2014 Quenches Quench event induced by sudden loss of 20 mA of the stored beam Magnet temperatures were recovered quickly (2-3 min). 38 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.

SCU R&D Review, Jan. 31, 2014 SCU0 X-ray performance 39 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.