Beam based alignment of C-shaped quadrupole magnets

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Description

Many storage rings have implemented a method of finding the positional offset between the electrical center of the beam position monitors (BPM) and the magnetic center of the adjacent quadrupole magnets. The algorithm for accomplishing this is usually based on modulating the current in the quadrupole magnet and finding the beam position that minimizes the orbit perturbation. When the quadrupole magnet is C-shaped, as it is for many light sources, the modulation method can produce an erroneous measurement of the magnetic center in the horizontal plane. When the current in a C-shaped quadrupole is changed, there is an additional dipole ... continued below

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4 p.

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Portmann, G. & Robin, D. June 1, 1998.

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Description

Many storage rings have implemented a method of finding the positional offset between the electrical center of the beam position monitors (BPM) and the magnetic center of the adjacent quadrupole magnets. The algorithm for accomplishing this is usually based on modulating the current in the quadrupole magnet and finding the beam position that minimizes the orbit perturbation. When the quadrupole magnet is C-shaped, as it is for many light sources, the modulation method can produce an erroneous measurement of the magnetic center in the horizontal plane. When the current in a C-shaped quadrupole is changed, there is an additional dipole component in the vertical field. Due to nonlinearities in the hysteresis cycle of the C-magnet geometry, the beam-based alignment technique at the Advanced Light Source (ALS) deviated horizontally by .5 mm from the actual magnetic center. By modifying the technique, the offsets were measured to an accuracy of better than 50 {micro}m.

Physical Description

4 p.

Notes

INIS; OSTI as DE98057485

Source

  • EPAC 1998: 6. European particle accelerator conference, Stockholm (Sweden), 22-26 Jun 1998

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  • Other: DE98057485
  • Report No.: LBNL--41249
  • Report No.: CONF-980671--
  • Grant Number: AC03-76SF00098
  • Office of Scientific & Technical Information Report Number: 674706
  • Archival Resource Key: ark:/67531/metadc703507

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  • June 1, 1998

Added to The UNT Digital Library

  • Sept. 12, 2015, 6:31 a.m.

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  • Nov. 4, 2015, 3:20 p.m.

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Portmann, G. & Robin, D. Beam based alignment of C-shaped quadrupole magnets, article, June 1, 1998; United States. (digital.library.unt.edu/ark:/67531/metadc703507/: accessed August 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.