BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:The LHC Transverse coupled-Bunch Instability
DTSTART;VALUE=DATE-TIME:20120426T121500Z
DTEND;VALUE=DATE-TIME:20120426T131500Z
DTSTAMP;VALUE=DATE-TIME:20130525T185024Z
UID:indico-event-187663@cern.ch
DESCRIPTION:We address here the problem of the transverse coupled-bunch in
 stabilities created by the Large Hadron Collider (LHC) beam-coupling imped
 ance\, that can possibly limit the machine operation. A rather complete vi
 sion of the problem is proposed\, going from the calculation of the impeda
 nces and wake functions of individual machine elements\, to the beam dynam
 ics study. New results are obtained in the theory of the beam-coupling imp
 edance for an axisymmetric two-dimensional structure\, generalizing Zotter
 's theories\, and a new general theory is derived for the impedance of an 
 infinite flat two-dimensional structure. Then\, a new approach is found to
  compute the wake functions from such analytically obtained beam-coupling 
 impedances\, overcoming limitations that could be met with standard discre
 te Fourier transform procedures. Those results are used to obtain an imped
 ance and wake function model of the LHC\, based on the (resistive-) wall i
 mpedances of various contributors (collimators\, beam screens and vacuum p
 ipe) and additional estimations of the geometrical impedance contributions
 . Finally\, the existing code HEADTAIL is improved to make possible the si
 mulation of multibunch trains. All those theories and tools are used to ob
 tain new results concerning the LHC transverse coupled-bunch instabilities
 \, comparing them with actual measurements in the LHC\, providing a very g
 ood agreement at injection energy and a correct order of magnitude at 3.5 
 TeV/c.\n\nATS Seminars\nOrganisers: H. Burkhardt (BE)\, S. Sgobba (EN)\, G
 . deRijk (TE)\n\nhttp://indico.cern.ch/conferenceDisplay.py?confId=187663
LOCATION:CERN Kjell Johnsen Auditorium
URL:http://indico.cern.ch/conferenceDisplay.py?confId=187663
END:VEVENT
END:VCALENDAR