Observation of a periodic pattern in the persistent-current fields of the superconducting HERA magnets

Conference · Wed May 01 00:00:00 EDT 1991

OSTI ID:5528743

Brueck, H; Gall, D; Krzywinski, J; Meinke, R; Preissner, H ^[1]; Halemeyer, M; Schmueser, P; Stolzenburg, C ^[2]; Stiening, R ^[3]; ter Avest, D; van de Klundert, L J.M. ^[4]

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1. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.)
2. Hamburg Univ. (Germany, F.R.). 2. Inst. fuer Experimentalphysik
3. Superconducting Super Collider Lab., Dallas, TX (USA)
4. Technische Hogeschool Twente, Enschede (Netherlands

The time dependence of persistent current multipoles in superconducting magnets is still unexplained. The decay is too large to be accounted for by flux creep and it does not show the expected dependence on temperature. Furthermore the decay is influenced by a preceding field sweep in the magnet, it becomes more pronounced if the magnet was previously excited to its maximum field. For a detailed study of the decay mechanism a special sensor has been developed which allows to record small sexupole components in superconducting dipole magnets. During an experimental study of the time dependence of a HERA dipole it was found that the sextupole field exhibits a sinusoidal structure along the axis of the magnet. A similar periodic structure was found for the main dipole field with the help of a nuclear magnetic resonance probe. The wavelength of the periodic pattern is compatible with the transposition pitch of the Rutherford-type cable in the magnet coils. The structure was found to exist in all HERA dipoles measured afterwards and also in a superconducting coil without iron yoke. With a specially developed 2 cm long pickup coil it was found that all accessible multipole components in dipole and quadrupole magnets are modulated along their axis. 3 refs., 6 figs.

• Research Organization: Superconducting Super Collider Lab., Dallas, TX (USA)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC02-89ER40486
• OSTI ID: 5528743
• Report Number(s): SSCL-414; CONF-910505-339; ON: DE91014888; TRN: 91-019014
• Resource Relation: Conference: 1991 Institute of Electrical and Electronics Engineers (IEEE) particle accelerator conference (PAC), San Francisco, CA (USA), 6-9 May 1991
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
MAGNETIC FIELDS
VARIATIONS
SUPERCONDUCTING MAGNETS
FLUCTUATIONS
HERA STORAGE RING
MAGNETIC DIPOLES
MULTIPOLES
QUADRUPOLES
QUENCHING
TIME DEPENDENCE
DIPOLES
ELECTRICAL EQUIPMENT
ELECTROMAGNETS
EQUIPMENT
MAGNETS
STORAGE RINGS
SUPERCONDUCTING DEVICES
430400* - Particle Accelerators- Storage Rings
430303 - Particle Accelerators- Experimental Facilities & Equipment