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MD: Variable T ransverse Damper Gain, Tune Measurement and Emittance Preservation

MD: Variable T ransverse Damper Gain, Tune Measurement and Emittance Preservation. presented by W. Hofle. Participants : D. Valuch , W. Hofle , F. Dubouchet , V. Kain , M. Kuhn, F. Roncarolo , M. Gasior , R. Steinhagen , and. Proposal from Chamonix 2012.

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MD: Variable T ransverse Damper Gain, Tune Measurement and Emittance Preservation

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  1. MD: Variable Transverse Damper Gain, Tune Measurement and Emittance Preservation presented by W. Hofle Participants: D. Valuch, W. Hofle, F. Dubouchet, V. Kain, M. Kuhn, F. Roncarolo, M. Gasior, R. Steinhagen , and LHC MSWG

  2. Proposal from Chamonix 2012 lower ADT gain for first bunch train of 12 bunches implement in ADT observation of two selectable bunches observe results of lower gain, incl. on BBQ (gated BBQ ?) check practical feasibility of tune from residual damper signa LHC MSWG

  3. ADT through the cycle LHC MSWG

  4. How we ran in 2011 with 50 ns beam damper gain hor beam 1 (linear scale) HIGH @450 GeV before prepare for ramp increase of damper (electronic) gain in ramp To maintain approx. same damping rate ramp (energy) drop of damper gain increased BBQ amplitude = more residual beam oscillations => potentially leading to blow-up; but signal needed for tune feedback which is switched on here BBQ hor Beam 1 amplitude prepare for ramp ramp Injection plateau LHC MSWG

  5. Objectives of proposed MD • investigate if higher ADT FB gain is cure for blow-up in ramp • improve compatibility of ADT and tune feedback by • witness bunch(es) with lower ADT gain • collect data for investigation of practical feasibility of tune • measurement from ADT PU data New features prepared on ADT side for 2012 (D. Valuch) • New 16k memory block(s) on FPGA for quasi continuous observation, for example 8 bunches each 2048 turns • Gain modulation, bunch selective, batch-by-batch (limited only by bandwidth of power system) in digital part of FB loop LHC MSWG

  6. Proposal for 1st MD Block 2012 (1) • inject 8 bunches per beam • one bunch per beam shall have 20% more intensity • (the “witness” bunch) • witness bunch without transverse feedback (zero gain) •  check if good BBQ signal at 450 GeVwhen • changing ADT FB gain for remaining 7 bunches • if OK, enable gain modulation for the 7 bunches • if OK lock tune feedback, then ramp with tune feedback and gain modulation LHC MSWG

  7. Proposal for 1st MD Block 2012 (2) Observations • bunch-by-bunch wire scanners • cleanliness of BBQ signal • ADT bunch-by-bunch data (tune dip, offline) • losses bunch-by-bunch Time • 6 hours, 1 ramp + preparation • Both beams, 8 nominal bunches per beam, nominal conditions, except ADT • stop MD at 4 TeV, if bunches good, can be used by other MD users LHC MSWG

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