Compensation for the effect of vacuum chamber eddy current by digital signal processing for closed orbit feedback

Conference · Thu Jul 01 00:00:00 EDT 1993

OSTI ID:10175712

Chung, Y; Emery, L; Kirchman, J

The Advanced Photon Source (APS) will implement both global and local beam position feedback systems to stabilize the particle and X-ray beams. The relatively thick (1/2 inch) aluminum storage ring vacuum chamber at corrector magnet locations for the local feedback systems will induce significant eddy current. This will reduce the correction bandwidth and could potentially destabilize the feedback systems. This paper describes measurement of the effect of the eddy current induced in the APS storage ring vacuum chamber by a horizontal/vertical corrector magnet and its compensation using digital signal processing at 4 kHz sampling frequency with proportional, integral, and derivative (PID) control algorithm for closed orbit feedback. A theory of digital feedback to obtain the linear system responses and the conditions for optimal control will also be presented. The magnet field in the vacuum chamber shows strong quadrupole and sextupole components varying with frequency, in addition to significant attenuation and phase shift with bandwidth ({minus}3 dB) of 20 Hz for horizontal and 4 Hz for vertical fields relative to the magnet current. Large changes in the magnet resistance and inductance were also observed, as the result of reduced total magnetic energy and increased Ohmic heat loss.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 10175712
• Report Number(s): ANL/ASD/CP-78357; CONF-930511-307; ON: DE93017700; TRN: 93:018011
• Resource Relation: Conference: PAC `93: international particle accelerator conference,Washington, DC (United States),17-20 May 1993; Other Information: PBD: [1993]
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ADVANCED PHOTON SOURCE
COMPUTERIZED CONTROL SYSTEMS
VACUUM SYSTEMS
DESIGN
MAGNETIC FIELDS
FEEDBACK
ORBIT STABILITY
EDDY CURRENTS
CORRECTIONS
DATA PROCESSING
ALGORITHMS
PHASE SHIFT
QUADRUPOLES
BEAM POSITION
BEAM MONITORS
POSITRON BEAMS
PHOTON BEAMS
DIGITAL FILTERS
DIGITAL SYSTEMS
IMPEDANCE
OPTIMAL CONTROL
430400
430300
STORAGE RINGS
AUXILIARIES AND COMPONENTS