Author: Hidaka, Y.
Paper Title Page
MOPAB039 Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II 175
 
  • L.H. Yu, G. Bassi, Y. Hidaka, B. Podobedov, V.V. Smaluk, G.M. Wang, X. Yang
    BNL, Upton, New York, USA
  
  The com­par­i­son of am­pli­tude tune de­pen­dence mea­sured for NSLSII lat­tices with mod­els in­di­cated the large change of am­pli­tude tune de­pen­dence over time ap­par­ently can not be solely ex­plained by mag­nets vari­a­tion or beta func­tion changes, but it seems can be ex­plained by en­ergy changes. On the other hand, the en­ergy change re­quired by fit­ting with the am­pli­tude tune de­pen­dence change is too large to be ex­plained by the RF fre­quency change and the change of the sum of cor­rec­tors in the pe­riod of the mea­sure­ments. To ex­plain this ap­par­ent con­tra­dic­tion, our analy­sis shows the long term stor­age ring cir­cum­fer­ence change can ex­plain the ap­par­ent en­ergy change. Our data in­deed shows a sea­sonal change of the am­pli­tude tune de­pen­dence over long term ob­ser­va­tion. This clearly also in­di­cated a re­la­tion to long term closed orbit drift. Hence the cur­rent work in­di­cates a new strat­egy to study how to use am­pli­tude tune de­pen­dence as a guide­line to an­a­lyze long term lat­tice pa­ra­me­ter shifts and closed orbit drift, and im­prove the orbit and ma­chine per­for­mance sta­bil­ity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039  
About • paper received ※ 09 May 2021       paper accepted ※ 26 May 2021       issue date ※ 26 August 2021  
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MOPAB041 Convergence Map with Action-Angle Variables Based on Square Matrix for Nonlinear Lattice Optimization 182
 
  • L.H. Yu, Y. Hidaka, F. Plassard, V.V. Smaluk
    BNL, Upton, New York, USA
  • Y. Hao
    FRIB, East Lansing, Michigan, USA
  
  We apply square ma­trix method to ob­tain in high speed a "con­ver­gence map", which is sim­i­lar but dif­fer­ent from fre­quency map. The con­ver­gence map is ob­tained from solv­ing non­lin­ear dy­nam­i­cal equa­tion by it­er­a­tion of per­tur­ba­tion method and study the con­ver­gence. The map pro­vides in­for­ma­tion about the sta­bil­ity bor­der of dy­nam­i­cal aper­ture. We com­pare the map with fre­quency map from track­ing. The re­sult in­di­cates the new method may be ap­plied in non­lin­ear lat­tice op­ti­miza­tion, tak­ing the ad­van­tage of the high speed (about 10~50 times faster) to ex­plore x, y and the off-mo­men­tum phase space.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB041  
About • paper received ※ 09 May 2021       paper accepted ※ 26 May 2021       issue date ※ 18 August 2021  
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TUPAB227 Simultaneous Compensation of Phase and Amplitude Dependent Geometrical Resonances Using Octupoles 1960
 
  • F. Plassard, Y. Hidaka, Y. Li, T.V. Shaftan, V.V. Smaluk, G.M. Wang
    BNL, Upton, New York, USA
  
  As the new gen­er­a­tion of light sources are push­ing to­ward dif­frac­tion lim­ited stor­age rings with ul­tra-low emit­tance beams, non­lin­ear beam dy­nam­ics be­come in­creas­ingly dif­fi­cult to con­trol. It is a com­mon prac­tice for mod­ern de­signs to use a sex­tu­pole scheme that al­lows si­mul­ta­ne­ous cor­rec­tion of nat­ural chro­matic­ity and en­ergy in­de­pen­dent, or geo­met­ri­cal, sex­tupo­lar res­o­nances. How­ever, the re­main­ing higher order terms aris­ing from the cross talks of the sex­tu­pole fam­i­lies set a strong lim­i­ta­tion on the achiev­able dy­namic aper­ture. This paper pre­sents a sim­u­la­tion-based recipe to use oc­tupoles to­gether with this sex­tu­pole scheme to pro­vide si­mul­ta­ne­ous self-com­pen­sa­tion of lin­ear am­pli­tude de­pen­dent tune shift to­gether with phase-de­pen­dent oc­tupo­lar and higher order geo­met­ri­cal res­o­nant dri­ving terms. The cor­rec­tion method was built based on ob­ser­va­tions made on a sim­ple FODO model, then ap­plied to a re­al­is­tic low emit­tance lat­tice, de­signed in the frame­work of the up­grade of the Na­tional Syn­chro­tron Light Source II (NSLS-II).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB227  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 14 August 2021  
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THXB04 Non-Invasive Dispersion Function Measurement during Light Source Operations 3720
 
  • B. Podobedov, Y. Hidaka
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
We im­ple­mented a com­pletely par­a­sitic mea­sure­ment of lat­tice dis­per­sion func­tions in both hor­i­zon­tal and ver­ti­cal planes, which is fully com­pat­i­ble with light source user op­er­a­tions. The mea­sure­ment is per­formed by ap­ply­ing prin­ci­pal com­po­nent analy­sis and adap­tive fil­ter­ing to very small resid­ual orbit noise com­po­nents in­tro­duced by the RF sys­tem and de­tected in the beam orbit data, sam­pled at 10 kHz. No changes in RF fre­quency are re­quired. The mea­sure­ment, per­formed once a minute, was shown to be ro­bust and im­mune to changes in the beam cur­rent, resid­ual orbit noise am­pli­tude and fre­quency con­tent as well as other fac­tors. At low cur­rent it was shown to pro­vide sim­i­lar ac­cu­racy to the tra­di­tional method (which shifts the 500 MHz RF fre­quency by ±500 Hz). In this paper we will ex­plain our mea­sure­ment tech­nique and pre­sent typ­i­cal dis­per­sion func­tion sta­bil­ity achieved dur­ing NSLS-II op­er­a­tions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXB04  
About • paper received ※ 26 June 2021       paper accepted ※ 13 July 2021       issue date ※ 23 August 2021  
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THPAB197 Enhancing Efficiency of Multi-Objective Neural-Network-Assisted Nonlinear Dynamics Lattice Optimization via 1-D Aperture Objectives & Objective Focusing 4156
 
  • Y. Hidaka, D.A. Hidas, F. Plassard, T.V. Shaftan, G.M. Wang
    BNL, Upton, New York, USA
  
  Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704.
Mutli-ob­jec­tive op­ti­miz­ers such as multi-ob­jec­tive ge­netic al­go­rithm (MOGA) have been quite pop­u­lar in dis­cov­er­ing de­sir­able lat­tice so­lu­tions for ac­cel­er­a­tors. How­ever, even these suc­cess­ful al­go­rithms can be­come in­ef­fec­tive as the di­men­sion and range of the search space in­crease due to ex­po­nen­tial growth in the amount of ex­plo­ration re­quired to find global op­tima. This dif­fi­culty is even more ex­ac­er­bated by the re­source-in­ten­sive and time-con­sum­ing ten­dency for the eval­u­a­tions of non­lin­ear beam dy­nam­ics. Lately the use of sur­ro­gate mod­els based on neural net­work has been draw­ing at­ten­tion to al­le­vi­ate this prob­lem. Fol­low­ing this trend, to fur­ther en­hance the ef­fi­ciency of non­lin­ear lat­tice op­ti­miza­tion for stor­age rings, we pro­pose to re­place typ­i­cally used ob­jec­tives with those that are less time-con­sum­ing and to focus on a sin­gle ob­jec­tive con­structed from mul­ti­ple ob­jec­tives, which can max­i­mize uti­liza­tion of the trained mod­els through local op­ti­miza­tion and ob­jec­tive gra­di­ent ex­trac­tion. We demon­strate these en­hance­ments using a NSLS-II up­grade lat­tice can­di­date as an ex­am­ple. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB197  
About • paper received ※ 20 May 2021       paper accepted ※ 23 June 2021       issue date ※ 10 August 2021  
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THPAB198 Commissioning of Current Strips for Elliptically Polarizing Undulators at NSLS-II 4160
 
  • Y. Hidaka, O.V. Chubar, T. Tanabe
    BNL, Upton, New York, USA
  • C.A. Kitégi
    SOLEIL, Gif-sur-Yvette, France
  
  Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704.
Most of the El­lip­ti­cally Po­lar­iz­ing Un­du­la­tors (EPUs) at NSLS-II are equipped with cur­rent strips (or flat wires), at­tached to their vac­uum cham­bers. These strips com­pen­sate the dy­namic field in­te­grals of the EPU to min­i­mize un­de­sir­able non­lin­ear beam dy­nam­ics ef­fect that can lead to re­duc­tion in in­jec­tion ef­fi­ciency and beam life­time. For each EPU, we mea­sured the field in­te­grals of the in­ser­tion de­vice alone, the cur­rent strips alone, and both, while cre­at­ing hor­i­zon­tal bumps of dif­fer­ent am­pli­tudes at the straight sec­tion to as­sess the ef­fec­tive­ness of the com­pen­sa­tion pro­vided by the de­sign cur­rent val­ues for the strips. The com­mis­sion­ing re­sults of these cur­rent strips are re­ported in this ar­ti­cle. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB198  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 28 August 2021  
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