Author: Caiafa, G.
Paper Title Page
SUPAG03 Challenges in Extracting Pseudo-Multipoles From Magnetic Measurements 87
 
  • S. Russenschuck, G. Caiafa, L. Fiscarelli, M. Liebsch, C. Petrone, P. Rogacki
    CERN, Geneva, Switzerland
  
  Ex­tract­ing the co­ef­fi­cients of Fourier-Bessel se­ries, known as pseudo-mul­ti­poles or gen­er­al­ized gra­di­ents, from mag­netic mea­sure­ments of ac­cel­er­a­tor mag­nets in­volves tech­ni­cal and math­e­mat­i­cal chal­lenges. First, a novel de­sign of a short, ro­tat­ing-coil mag­ne­tome­ter is re­quired that does not in­ter­cept any axial field com­po­nent of the mag­net. More­over, dis­plac­ing short mag­ne­tome­ters, step-by-step along the mag­net axis, yields a con­vo­lu­tion of the local mul­ti­pole field er­rors and the sen­si­tiv­ity (test func­tion) of the in­duc­tion coil. The de­con­vo­lu­tion must then con­tent with the low sig­nal-to-noise ratio of the mea­sur­ands, which are in­te­grated volt­ages cor­re­spond­ing to spa­tial flux dis­tri­b­u­tions. Fi­nally, the com­pen­sa­tion schemes, as im­ple­mented on long coils used for mea­sur­ing the in­te­grated field har­mon­ics, can­not be ap­plied to short mag­ne­tome­ters. All this re­quires care­ful de­sign of ex­per­i­ment to de­rive the op­ti­mal length of the in­duc­tion coil, the step size of the scan, and the high­est order of pseudo-mul­ti­poles in the field re­con­struc­tion. This paper pre­sents the the­ory of the mea­sure­ment method, the data ac­qui­si­tion and de­con­vo­lu­tion, and the de­sign and pro­duc­tion of a sad­dle-shaped, ro­tat­ing-coil mag­ne­tome­ter.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG03  
About • paper received ※ 18 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
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