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Published byRalph Harrington Modified over 9 years ago
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BIW 2006 Simultaneous Tune and Coupling Feedback during RHIC Run 6 Peter Cameron
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BIW 2006
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Acknowledgements Tom Shea – the foundation and foresight Mike Harrison, Steve Peggs, Alex Ratti –US LHC Accelerator Research Program RHIC HF Instrumentation –Earlier efforts BNL C-AD Instrumentation – Tom Russo et al –The present effort
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BIW 2006 Outline System Architecture Direct Diode Detection (3D) AFE Eigenmodes, set and measured tunes,… Coupling and de-coupling –essential for tune feedback Ramping with and w/o feedbacks 3D AFE ‘Beam Noise’ Susceptibility Plans
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BIW 2006
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10nm
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BIW 2006 eigenmodes rotated wrt horizontal and vertical planes due to coupling. special case general case
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BIW 2006 Set and Measured Tunes Measured tunes –The ‘eigenvalues’ – physical observables –Rotated from H and V by coupling Set tunes –What tune would be in the absence of coupling –dQ min – forbidden zone complicates tune control without feedback breaks feedback –can be calculated with knowledge of coupling
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BIW 2006 Set and Measured Tunes set measured
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BIW 2006 tune feedback would break here
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BIW 2006 Manual Decoupling Skew chrom 0 Chrom measurement
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BIW 2006 dQ min <.001
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BIW 2006
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Coupling Echoes ½ synchrotron period 1 sec Coupling coefficient ‘C’ 0.02
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BIW 2006 Outline System Architecture Direct Diode Detection (3D) AFE Eigenmodes, set and measured tunes,… Coupling and de-coupling –essential for tune feedback Ramping with and w/o feedbacks 3D AFE ‘Beam Noise’ Susceptibility Plans
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BIW 2006 First Ramp with Feedbacks
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BIW 2006 First Ramp with Feedbacks 2
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BIW 2006 Last Blue Ramp with Feedbacks
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BIW 2006 Next Ramp with Feedbacks Off
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BIW 2006 Beam Noise Steve Peggs – “declare Victory” Peter Cameron – “Mission Accomplished” One messy little detail –3D AFE sensitivity to ‘beam noise’ –No free lunch
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BIW 2006 3D AFE ‘beam noise’ Beautiful when looking at amplitude –Very sensitive ~10nm –Resistant to dynamic range problems (bunch length, beam offset,…) But, when you put it in a phase loop…. Possible sources –Beam loss –High frequencies - longitudinal ‘hot spots’ –Low frequencies quadrupole cryostat vibrations mains harmonics –Instabilities (weak – not noticed by anything except 3D AFE) –Long range beam-beam
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BIW 2006 Immediate plans Further investigation of ‘beam noise’, and how to cope with this Chromaticity measurement and feedback Movement of the system into the CERN architecture – DAB board
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BIW 2006Conclusions World’s first implementation of simultaneous tune and coupling feedback is successful The door remains open for simultaneous tune, coupling and chromaticity feedback at LHC
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BIW 2006 Back-up slides
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BIW 2006 3D on the Ramp - 1 Jan 05 dominant spacing is 180Hz 60Hz onset 60Hz end IPM every 100 turns (780 Hz)
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BIW 2006 Transverse instability Not fixed by chrom Frequently present at a level not detectable by anything other than BBQ Upper half of sideband
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BIW 2006 Summary of Chromaticity tt tt vert horiz +5 -5 dp/p of +/-10 -4 gives ~+/-100 radial modulation (RHIC&LHC) -5 +5 Q' ramp 6380 ramp 6382 ramp 6381 in RHIC modulation is at 1Hz chrom - good results under sequencer control
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