Author: Hans, O.
Paper Title Page
MOPS013 Transverse Low Frequency Broad-band Impedance Measurements in the CERN PS 622
 
  • S. Aumon
    EPFL, Lausanne, Switzerland
  • P. Freyermuth, S.S. Gilardoni, O. Hans, E. Métral, G. Rumolo
    CERN, Geneva, Switzerland
  
  The base-line sce­nario for the High-Lu­mi­nos­i­ty LHC up­grade fore­sees an in­ten­si­ty in­crease de­liv­ered by the in­jec­tors. With its 53 years, the CERN PS would have to op­er­ate be­yond the limit of its per­for­mances to match the fu­ture re­quire­ments. Beam in­sta­bil­i­ties driv­en by trans­verse impedance are an im­por­tant issue for the op­er­a­tion of high in­ten­si­ty beams as for the high-bright­ness LHC beams. Mea­sure­ments of trans­verse tune de­pen­dence with beam in­ten­si­ty were per­formed at in­jec­tion ki­net­ic en­er­gy 1.4~GeV and at LHC beam ex­trac­tion mo­men­tum 26~GeV/c. This al­lows de­duc­ing the low fre­quen­cy in­duc­tive broad-band impedance of the ma­chine. Then an es­ti­ma­tion of the real part of the impedance is made by the rise time mea­sure­ment of a fast trans­verse in­sta­bil­i­ty be­lieved to be a TMCI type. Those are the first step to­wards a glob­al ma­chine impedance char­ac­ter­i­za­tion in order to push for­ward the per­for­mances of the ac­cel­er­a­tor.  
 
MOPS009 Probing Intensity Limits of LHC-type Bunches in the CERN SPS with Nominal Optics 610
 
  • B. Salvant, G. Adrian, D.J. Allen, O. Andujar, T. Argyropoulos, J. Axensalva, J. Baldy, H. Bartosik, S. Cettour Cave, F. Chapuis, J.F. Comblin, K. Cornelis, D.G. Cotte, K. Cunnington, H. Damerau, M. Delrieux, J.L. Duran-Lopez, A. Findlay, J. Fleuret, F. Follin, P. Freyermuth, H. Genoud, S.S. Gilardoni, A. Guerrero, S. Hancock, K. Hanke, O. Hans, R. Hazelaar, W. Höfle, L.K. Jensen, J. Kuczerowski, Y. Le Borgne, R. Maillet, D. Manglunki, S. Massot, E. Matli, G. Metral, B. Mikulec, E. Métral, J.-M. Nonglaton, E. Ovalle, L. Pereira, F.C. Peters, A. Rey, J.P. Ridewood, G. Rumolo, J.L. Sanchez Alvarez, E.N. Shaposhnikova, R.R. Steerenberg, R.J. Steinhagen, J. Tan, B. Vandorpe, E. Veyrunes
    CERN, Geneva, Switzerland
  
  Some of the up­grade sce­nar­ios of the high-lu­mi­nos­i­ty LHC re­quire large in­ten­si­ty per bunch from the in­jec­tor chain. Sin­gle bunch beams with in­ten­si­ties of up to 3.5 to 4·1011 p/b and nom­i­nal emit­tances were suc­cess­ful­ly pro­duced in the PS Com­plex and de­liv­ered to the SPS in 2010. This con­tri­bu­tion pre­sents re­sults of stud­ies with this new in­tense beam in the SPS to probe sin­gle bunch in­ten­si­ty lim­i­ta­tions with nom­i­nal gamma tran­si­tion. In par­tic­u­lar, the ver­ti­cal Trans­verse Mode Cou­pling In­sta­bil­i­ty (TMCI) thresh­old with low chro­matic­i­ty was ob­served at 1.6·1011 p/b for sin­gle nom­i­nal LHC bunch­es in the SPS. With in­creased ver­ti­cal chro­matic­i­ty, larg­er in­ten­si­ties could be in­ject­ed, stored along the flat bot­tom and ac­cel­er­at­ed up to 450 GeV/c. How­ev­er, sig­nif­i­cant loss­es and/or trans­verse emit­tance blow up were then ob­served. Lon­gi­tu­di­nal and trans­verse op­ti­miza­tion ef­forts in the PSB, PS and SPS were put in place to min­i­mize this beam degra­da­tion and suc­ceed­ed to ob­tain sin­gle 2.3·1011 p/b LHC type bunch­es with sat­is­fy­ing pa­ram­e­ters at ex­trac­tion of the SPS.