Transcript Feed Forward Compensation

Feed Forward Compensation
This work is mainly done by
Fumihiko Tamura
Feed Forward System of RCS
Multi-Harmonics to compensate
Procedures
Step 1: Get Transfer function (w/o beam)
Step 2: Get Cavity impedance seen by beam
Step 3: Get Transfer function from beam current to FF
Impedance seen by beam
Gap voltage
Synchronous phase
Beam Loss at high intensity
DCCT can not tell but Loss monitor tells
Summary
• Impedance seen by beam becomes less than 25 Ohm from
800 Ohm.
• Waveform distortion on gap voltage disappeared and loss
at the arc sections was also disappeared.
• Feed forward system worked satisfactorily.
– Combination of MA cavity & Digital LLRF
• RCS LLRF is ready to handle 1 MW beam.
• If any questions : [email protected]
• Reference: F. Tamura, et al.: \Multi-harmonic rf
feedforward system for beamloading compensation in
wide-band cavities of a rapid cycling synchrotron", Phys.
Rev. ST Accel. Beams, 14, 051004 (2011).