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

Conference · Thu Jul 01 04:00:00 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
• Country of Publication: United States
• Language: English

Related Subjects

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