Author: Huck, M.
Paper Title Page
WEPAB133 First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II 2925
 
  • M. Huck, J. Bahrdt, A. Meseck
    HZB, Berlin, Germany
  • A. Meseck
    KPH, Mainz, Germany
  
  While the new in-vac­uum cryo­genic un­du­la­tor is in its last com­mis­sion­ing stages, a world­wide new in-vac­uum APPLE II un­du­la­tor is being de­signed and con­structed for BESSY II stor­age ring. Be­sides the chal­leng­ing me­chan­i­cal de­sign of these small-gap and short-pe­riod un­du­la­tors, chal­lenges arise due to in­ter­ac­tion with the elec­tron beam. There­fore, de­tailed stud­ies of this in­ter­ac­tion is re­quired to min­i­mize the ad­verse ef­fects on beam dy­nam­ics and the de­vice it­self. For this pur­pose, the wake­field ef­fects have been com­puted nu­mer­i­cally for crit­i­cal parts of these de­vices i.e. the RF-shields, flex­i­ble ta­pers and taper sec­tions. A brief overview of sim­u­la­tion re­sults and dis­cus­sions are pre­sented in this paper.  
poster icon Poster WEPAB133 [0.795 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133  
About • paper received ※ 19 May 2021       paper accepted ※ 23 July 2021       issue date ※ 23 August 2021  
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WEPAB134 Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II 2929
 
  • M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke
    HZB, Berlin, Germany
  
  A new in-vac­uum cryo­genic per­ma­nent mag­net un­du­la­tor (CP­MU17) has been in­stalled in sum­mer 2018 in the BESSY II stor­age ring at HZB. Such a small gap in-vac­uum un­du­la­tor de­vice in­creases the im­ped­ance of the stor­age ring and can con­tribute to the in­sta­bil­i­ties that ad­versely af­fect the beam qual­ity and the de­vice it­self. To iden­tify and ex­plore the ef­fects of CP­MU17 on the in­sta­bil­i­ties at BESSY II, grow-damp and drive-damp ex­per­i­ments have been con­ducted using the in­stalled bunch-by-bunch feed­back sys­tem. In this paper, the first re­sults of the mode and gap analy­sis of these stud­ies with a brief overview of other im­ped­ance stud­ies will be pre­sented.  
poster icon Poster WEPAB134 [1.079 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134  
About • paper received ※ 17 May 2021       paper accepted ※ 02 July 2021       issue date ※ 23 August 2021  
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THPAB057 Goubau-Line Set Up for Bench Testing Impedance of In-Vacuum Undulator Components 3883
 
  • P.I. Volz, S. Grimmer, M. Huck, 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 soft X-ra­di­a­tion 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. Since its com­plex struc­ture makes nu­mer­i­cal cal­cu­la­tions, such as CST sim­u­la­tions, at high fre­quency very re­source in­ten­sive, bench test­ing the de­vice may proof in­valu­able. 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. This can be used to mea­sure the im­ped­ance of vac­uum cham­ber com­po­nents. A con­cept op­ti­mized for bench test­ing IVUE32-com­po­nents will be dis­cussed and progress to­wards the test bench set up will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB057  
About • paper received ※ 19 May 2021       paper accepted ※ 23 July 2021       issue date ※ 21 August 2021  
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