MC2: Photon Sources and Electron Accelerators
T15: Undulators and Wigglers

Paper	Title	Page
WEIYSP1	New Designs of Short-Period Undulators for Producing High-Brightness Radiation in Synchrotron Light Sources	1624
	E.J. Wallén LBNL, Berkeley, California, USA
	We re­view mod­ern state-of-the-art and new con­cepts of un­du­la­tors planned for new gen­er­a­tion light sources. Both su­per­con­duct­ing and per­ma­nent-mag­net-based in­ser­tion de­vices fea­ture unique so­lu­tions to reach high pre­cisely tun­able fields in the pe­riod range of 10-18 mm, 2-4 me­ters in length and with the ID gaps of less than 5 mm. The same quest for small gaps and short­est pos­si­ble pe­riod length ex­ists also for el­lip­ti­cally po­lar­iz­ing un­du­la­tors. A re­view of new de­signs in Eu­rope, Asia and Amer­i­cas will be in the focus of this pre­sen­ta­tion.
	Slides WEIYSP1 [21.171 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIYSP1
About •	Received ※ 15 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 07 July 2022
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THPOPT002	Beam Power Deposition on the Cryogenic Permanent Magnet Undulator	2556
	L.R. Carver, C. Benabderrahmane, P. Brumund, N. Carmignani, J. Chavanne, G. Le Bec, R. Versteegen, S.M. White ESRF, Grenoble, France
	X-rays with high bril­liance and low phase er­rors are gen­er­ated in the Cryo­genic Per­ma­nent Mag­net Un­du­la­tor (CPMU) cur­rently in use at the ESRF. In the event of a fail­ure of the cryo­genic cool­ing the beam will con­tinue to de­posit power into the mod­ule, even when the un­du­la­tor jaws are fully opened. This could lead to un­ac­cept­ably high heat­ing of the mag­net blocks which could cause their de­mag­neti­sa­tion. Im­ped­ance sim­u­la­tions were per­formed using IW2D and CST to com­pute the power de­posited by the beam in both the closed and open jaw set­tings. This was fol­lowed by ther­mal sim­u­la­tions to com­pute the ex­pected tem­per­a­ture rise. These re­sults will help ad­vise the op­er­a­tional pro­ce­dure in the event of a cool­ing fail­ure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT002
About •	Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 27 June 2022
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THPOPT032	SUNDAE2 at EuXFEL: A Test Stand to Characterize the Magnetic Field of Superconducting Undulators	2649
	J.E. Baader, S. Abeghyan, S. Casalbuoni, D. La Civita, B. Marchetti, M. Yakopov, P. Ziolkowski EuXFEL, Schenefeld, Germany H.-J. Eckoldt, A. Hauberg, S. Lederer, L. Lilje, T. Wohlenberg, R. Zimmermann DESY, Hamburg, Germany A.W. Grau KIT, Eggenstein-Leopoldshafen, Germany
	Eu­ro­pean XFEL fore­sees a su­per­con­duct­ing un­du­la­tor (SCU) af­ter­burner in the SASE2 hard X-ray beam­line. It con­sists of six 5m-long un­du­la­tor mod­ules with a 5mm vac­uum gap, where each mod­ule con­tains two 2m-long coils and one phase shifter. Prior to in­stal­la­tion, the mag­netic field must be mapped ap­pro­pri­ately. Two mag­netic mea­sure­ment test stands named SUN­DAE 1 and 2 (Su­per­con­duct­ing UN­Du­lA­tor Ex­per­i­ment) are being de­vel­oped at Eu­ro­pean XFEL. While SUN­DAE1 will be a ver­ti­cal test stand to mea­sure SCU coils up to two me­ters with Hall probes in a liq­uid or su­per­fluid he­lium bath, SUN­DAE2 will mea­sure the SCU coils as­sem­bled in the final cryo­stat. This con­tri­bu­tion pre­sents the de­vel­op­ment sta­tus of SUN­DAE2 and its main re­quire­ments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT032
About •	Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 28 June 2022
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THPOPT050	Development and Construction of Cryogenic Permanent Magnet Undulators for ESRF-EBS	2712
	C. Benabderrahmane, P. Brumund, J. Chavanne, D. Coulon, G. Le Bec, B. Ogier, R. Versteegen ESRF, Grenoble, France
	The ESRF Ex­tremely Bril­liant Source (ESRF-EBS) is on op­er­a­tion for Users since Au­gust 2020 after 20 months of shut­down. This first of a kind fourth gen­er­a­tion high en­ergy syn­chro­tron is based on a Hy­brid Multi-Bend Achro­mat lat­tice. The main goal of the ESRF-EBS is to re­duce the hor­i­zon­tal emit­tance, which leads to a sig­nifi-cant in­crease of the X-ray source bril­liance. To cover the in­ten­sive de­mand of short pe­riod small gap un­du­la­tors at ESRF-EBS, a new de­sign for a 2 m Cryo­genic Per­ma­nent Mag­net Un­du­la­tor (CPMU) has been de­vel­oped. Six CPMUs will be in­stalled in the next years; the first two CPMUs have been con­structed and ac­tu­ally used on ID15 and ID16 beam­line, the third one is under con-struct­ing. An in­ten­sive re­fur­bish­ment work has been done on the ex­ist­ing in­ser­tion de­vices to adapt them to the new ac­cel­er­a­tor which has shorter straight sec­tion and closer dipoles to the IDs than in the old one. This con­tri­bu­tion will re­view the de­vel­op­ment, con­struc-tion and com­mis­sion­ing of the new CPMUs, and the re­fur­bish­ment work done on the ex­ist­ing ones to adapt them to the new ac­cel­er­a­tor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT050
About •	Received ※ 02 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 18 June 2022
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THPOPT052	The Status of the In-Vacuum-APPLE II Undulator IVUE32 at HZB / BESSY II	2716
	J. Bahrdt, J. Bakos, S. Gaebel, S. Gottschlich, S. Grimmer, S. Knaack, C. Kuhn, F. Laube, A. Meseck, C. Rethfeldt, E.C.M. Rial, A. Rogosch-Opolka, M. Scheer, P.I. Volz HZB, Berlin, Germany
	At BESSY II, two new beam­lines for RIXS and for X-Ray-mi­croscopy de­mand a short pe­riod vari­ably po­lar­iz­ing un­du­la­tor. For this pur­pose, the first in-vac­uum APPLE un­du­la­tor world­wide is under con­struc­tion. The pa­ra­me­ters are as fol­lows: pe­riod length=32mm, mag­netic length=2500mm, min­i­mum gap=7mm. The de­sign in­cor­po­rates a force com­pen­sa­tion scheme as pro­posed by two of the au­thors at the SRI2018. All pre­ci­sion parts of the drive chain are lo­cated in air. New trans­verse slides for the trans­ver­sal slit ad­just­ment have been de­vel­oped and tested. Op­ti­cal mi­crom­e­ters mea­sure the gap and shift po­si­tions, sim­i­lar to the sys­tem of the CP­MU17 at BESSY II. They pro­vide the sig­nals for motor feed­back loops. A new UHV-com­pat­i­ble sol­der­ing tech­nique, as de­vel­oped with in­dus­try, re­laxes fab­ri­ca­tion tol­er­ances of mag­nets and mag­net hold­ers and sim­pli­fies the mag­net as­sem­bly. A 10-pe­riod pro­to­type has been setup for life­time tests of the new mag­netic keeper de­sign. The paper de­scribes first re­sults of the pro­to­type and other key-com­po­nents and sum­ma­rizes the sta­tus of the full-scale un­du­la­tor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT052
About •	Received ※ 19 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 22 June 2022
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THPOPT053	Goubau-Line Set Up for Bench Testing Impedance of IVU32 Components	2719
SUSPMF023	use link to see paper's listing under its alternate paper code
	P.I. Volz, A. Meseck HZB, Berlin, Germany A. Meseck KPH, Mainz, Germany
	The world­wide first in-vac­uum el­lip­ti­cal un­du­la­tor, IVUE32, is being de­vel­oped at Helmholtz-Zen­trum Berlin. The 2.5 m long de­vice with a pe­riod length of 3.2 cm and a min­i­mum gap of about 7 mm is to be in­stalled in the BESSY II stor­age ring. It will de­liver ra­di­a­tion in the soft X-ray range to sev­eral beam­lines. The prox­im­ity of the un­du­la­tor struc­ture to the elec­tron beam makes the de­vice sus­cep­ti­ble to wake­field ef­fects which can in­flu­ence beam sta­bil­ity. A com­plete un­der­stand­ing of its im­ped­ance char­ac­ter­is­tics is re­quired prior to in­stal­la­tion and op­er­a­tion, as un­fore­seen heat­ing of com­po­nents could have cat­a­strophic con­se­quences. To un­der­stand and mea­sure the IVU’s im­ped­ance char­ac­ter­is­tics a Goubau-Line test stand is being de­signed. A Goubau-line is a sin­gle wire trans­mis­sion line for high fre­quency sur­face waves with a trans­verse elec­tric field re­sem­bling that of a charged par­ti­cle beam out to a cer­tain ra­dial dis­tance. A con­cept op­ti­mized for bench test­ing IVUE32-com­po­nents will be dis­cussed, mi­crowave sim­u­la­tions will be pre­sented to­gether with first mea­sure­ments from a test stand pro­to­type.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT053
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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THPOPT058	Status and Powering Test Results of HTS Undulator Coils at 77 K for Compact FEL Designs	2726
SUSPMF024	use link to see paper's listing under its alternate paper code
	S.C. Richter, A. Bernhard, A.-S. Müller KIT, Karlsruhe, Germany A. Ballarino, T.H. Nes, S.C. Richter, D. Schoerling CERN, Meyrin, Switzerland
	Funding: This work has been supported by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E18CHA). The pro­duc­tion of low emit­tance positron beams for fu­ture lin­ear and cir­cu­lar lep­ton col­lid­ers, like CLIC or FCC-ee, re­quires high-field damp­ing wig­glers. Just as com­pact free-elec­tron lasers (FELs) re­quire high-field but as well short-pe­riod un­du­la­tors to emit high en­er­getic, co­her­ent pho­tons. Using high-tem­per­a­ture su­per­con­duc­tors (HTS) in the form of coated ReBCO tape su­per­con­duc­tors al­lows higher mag­netic field am­pli­tudes at 4 K and larger op­er­at­ing mar­gins as com­pared to low-tem­per­a­ture su­per­con­duc­tors, like Nb-Ti. This con­tri­bu­tion dis­cusses the de­vel­op­ment work on su­per­con­duct­ing ver­ti­cal race­track (VR) un­du­la­tor coils, wound from coated ReBCO tape su­per­con­duc­tors. The pre­sented VR coils were mod­u­larly de­signed with a pe­riod length of 13 mm. Pow­er­ing tests in liq­uid ni­tro­gen of mul­ti­ple ver­ti­cal race­track coils were per­formed at CERN. The re­sults from the mea­sure­ments are pre­sented for three VR coils and com­pared with elec­tro­mag­netic sim­u­la­tions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT058
About •	Received ※ 17 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 21 June 2022
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THPOPT060	Tolerance Study on the Geometrical Errors for a Planar Superconducting Undulator	2734
	V. Grattoni, S. Casalbuoni, B. Marchetti EuXFEL, Schenefeld, Germany
	At the Eu­ro­pean XFEL, a su­per­con­duct­ing af­ter­burner is con­sid­ered for the SASE2 hard X-ray beam­line. It will con­sist of six un­du­la­tor mod­ules. Within each mod­ule, two su­per­con­duct­ing un­du­la­tors (SCU) 2 m long are pre­sent. Such an af­ter­burner will en­able pho­ton en­er­gies above 30 keV. A high field qual­ity of the SCU is cru­cial to guar­an­tee the qual­ity of the elec­tron beam tra­jec­tory, which is di­rectly re­lated to the spec­tral qual­ity of the emit­ted free-elec­tron laser (FEL) ra­di­a­tion. There­fore, the ef­fects of the SCU’s me­chan­i­cal im­per­fec­tions on the re­sul­tant mag­netic field have to be care­fully char­ac­ter­ized. In this con­tri­bu­tion, we pre­sent pos­si­ble me­chan­i­cal er­rors af­fect­ing the un­du­la­tor struc­ture, and we per­form an an­a­lyt­i­cal study aimed at de­ter­min­ing the tol­er­ances on these er­rors for our SCUs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT060
About •	Received ※ 03 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 27 June 2022
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THPOPT061	European XFEL Undulators - Status and Plans	2737
	S. Casalbuoni, S. Abeghyan, J.E. Baader, U. Englisch, V. Grattoni, S. Karabekyan, B. Marchetti, H. Sinn, F. Wolff-Fabris, M. Yakopov, P. Ziolkowski EuXFEL, Schenefeld, Germany
	Eu­ro­pean XFEL has three un­du­la­tor lines based on per­ma­nent mag­net tech­nol­ogy: two for hard and one for soft X-rays. The pla­nar un­du­la­tors can be tuned to cover the ac­cep­tance in terms of pho­ton beam en­ergy of the re­spec­tive pho­ton beam­lines: 3.6-25 keV (SASE1/2) and 0.25-3 keV (SASE3) by chang­ing the elec­tron en­ergy range be­tween 11.5 GeV and 17.5 GeV and/or the un­du­la­tor gap. In order to ob­tain dif­fer­ent po­lar­iza­tion modes, as re­quired by the soft X-ray beam­lines, a he­li­cal af­ter­burner con­sist­ing of four APPLE X un­du­la­tors de­signed by PSI has been in­stalled at the down­stream end of the pre­sent SASE3 un­du­la­tor sys­tem. The Eu­ro­pean XFEL plans to de­velop the tech­nol­ogy of su­per­con­duct­ing un­du­la­tors, which is of strate­gic im­por­tance for the fa­cil­ity up­grade. In order to ex­tend the en­ergy range above 30 keV a su­per­con­duct­ing un­du­la­tor af­ter­burner is fore­seen to be in­stalled at the end of SASE2. This con­tri­bu­tion pre­sents the cur­rent sta­tus and the planned up­grades of the un­du­la­tor lines at Eu­ro­pean XFEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT061
About •	Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 04 July 2022
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THPOPT063	Design of Scilab Xcos Simulation Model for Pulsed Wire Method Data Analyses	2741
	H. Jeevakhan NITTTR, Bhopal, India S.M. Khan, G. Mishra Devi Ahilya University, Indore, India
	Pulsed wire method (PWM)is used for un­du­la­tor char­ac­ter­i­sa­tion. Scilab Xcos sim­u­la­tion model is de­signed for the analy­ses of data ob­tained by PWM. The data ob­tained from PWM is given as input to the model and its out­put gives the mag­netic field of the un­du­la­tor. Scilab Xcos model can also be uti­lized for de­ter­min­ing the phase error of the un­du­la­tor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT063
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 09 July 2022
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THPOPT064	Hall Probe Magnetic Measurement of 50 mm Period PPM Undulator	2744
SUSPMF025	use link to see paper's listing under its alternate paper code
	S.M. Khan, G. Mishra Devi Ahilya University, Indore, India M. Gehlot MAX IV Laboratory, Lund University, Lund, Sweden H. Jeevakhan NITTTR, Bhopal, India
	In this paper, we pre­sent the lat­est upgra­da­tion of Hall Probe mag­netic mea­sure­ment sys­tem. The Hall Probe mea­sure­ment sys­tem is up­graded with po­si­tion mea­sur­ing de­tec­tors and 3D F.W. Bell Tes­lame­ter. The field in­te­grals and the phase er­rors are cal­cu­lated with a new user friendly MAT­LAB code. The in­te­grated mul­ti­poles both nor­mal and skew com­po­nents are mea­sured and dis­cussed in the paper. The pro­posed ac­tiv­i­ties on 300 mm length pro­to­type asym­met­ric un­du­la­tor and 50 mm quasi pe­riod, six pe­riod length at Laser In­stru­men­ta­tion and In­ser­tion De­vice Ap­pli­ca­tion lab­o­ra­tory of Devi Ahilya Vishwa Vidyalaya (DAVV), In­dore, India has been dis­cussed and de­sign com­po­nents are pre­sented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT064
About •	Received ※ 06 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022
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THPOPT066	Helical Wiggler Design for Optical Stochastic Cooling at CESR	2751
	V. Khachatryan, M.B. Andorf, I.V. Bazarov, J.A. Crittenden, S.J. Levenson, J.M. Maxson, D.L. Rubin, J.P. Shanks, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA W.F. Bergan BNL, Upton, New York, USA
	Funding: The authors thank the Center for Bright Beams, NSF award PHY-1549132; W.F.B. was supported by the NSF Graduate Research Fellowship Program under grant number DGE-1650441. A he­li­cal wig­gler with pa­ra­me­ter kund=4.35 has been de­signed for the Op­ti­cal Sto­chas­tic Cool­ing (OSC) ex­per­i­ment in the Cor­nell Elec­tron Stor­age Ring (CESR). We con­sider four Hal­bach ar­rays, which di­men­sions are op­ti­mized to get the re­quired he­li­cal field pro­file, as well as, to get the best Dy­namic Aper­ture (DA) in sim­u­la­tions. The end poles are de­signed with dif­fer­ent di­men­sions to min­i­mize the first and sec­ond field in­te­grals to avoid the need of ad­di­tional cor­rec­tors for the beam orbit. The de­sign is adopted to min­i­mize the risks for the mag­net blocks de­mag­ne­ti­za­tion. To quan­tify the tol­er­ances, we sim­u­lated the ef­fects of dif­fer­ent types of geo­met­ri­cal and mag­netic field er­rors on the OSC damp­ing rates. In ad­di­tion, to un­der­stand the chal­lenges for the con­struc­tion, as well as, to val­i­date the model field cal­cu­la­tions, we pro­to­typed a small two pe­riod ver­sion. The pro­to­type field is com­pared to the model, and the re­sults are pre­sented in this work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT066
About •	Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 14 June 2022
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THPOTK010	Development of a Short Period Superconducting Helical Undulator	2788
	A.G. Hinton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J. Boehm, L. Cooper, B. Green, T. Hayler, P. Jeffery, C.P. Macwaters, B.J.S. Matthews STFC/RAL, Chilton, Didcot, Oxon, United Kingdom S. Milward DLS, Oxfordshire, United Kingdom B.J.A. Shepherd, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Su­per­con­duct­ing tech­nol­ogy pro­vides the pos­si­bil­ity to de­velop short pe­riod, small bore un­du­la­tors that can gen­er­ate much larger mag­netic fields than al­ter­na­tive tech­nolo­gies. This may allow an XFEL with op­ti­mised su­per­con­duct­ing un­du­la­tors to cover a broader range of wave­lengths than tra­di­tional un­du­la­tors. At STFC, we have un­der­taken work to de­sign and build a pro­to­type su­per­con­duct­ing he­li­cal un­du­la­tor mod­ule with pa­ra­me­ters suit­able for use on a fu­ture XFEL fa­cil­ity. This work in­cludes the de­sign of an un­du­la­tor with 13 mm pe­riod and 5 mm mag­netic gap, as well as the sup­port­ing cryo­genic and vac­uum sys­tems re­quired for op­er­a­tion. We pre­sent here the up­dated de­sign of the su­per­con­duct­ing he­li­cal un­du­la­tor that rep­re­sents the re­sults of pro­to­typ­ing work. Im­proved meth­ods for man­u­fac­tur­ing the un­du­la­tor for­mer and wind­ing the su­per­con­duct­ing wire have been de­vel­oped. The mea­sured me­chan­i­cal tol­er­ances and the im­pact on the field qual­ity will be pre­sented. The fields pro­duced by pro­to­type un­du­la­tors will soon be mea­sured using a Hall probe sys­tem.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK010
About •	Received ※ 06 June 2022 — Accepted ※ 10 June 2022 — Issue date ※ 17 June 2022
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