Status of Impedance studies G. Arduini, R. Calaga, E. Metral, D. Quatraro, G. Rumolo, B. Salvant and many others

Zbase TMCI in the SPS Impedance assessment

4 -weighed Wakefields / kicker Two available methods MAD-X Kickers geometry Kickers geometry Twiss file ZBase (rewall) ZBase (rewall) MAD-X 4 -weighed Wakefields / kicker 4 Wakefields/kicker Twiss file ZBase (sum) HeadTail With Lattice 4 -weighed Wakefields HeadTail Coherent motion Coherent motion See Diego’s talk for more details

ZBase : what to do next Urgent: A bit less urgent: Include other SPS elements and calculate the wake fields (simulated RF cavities, IPMs, BPMs, beam pipe, etc.) Include longitudinal impedance calculations A bit less urgent: Link MAD-X to Zbase, and not only the MAD-X output twiss file.

Zbase TMCI in the SPS Impedance assessment

HEADTAIL Simulations Vertical There is a beam current range around 8e10 where the vertical is stable and the horizontal is slightly unstable Horizontal

Vertical growth rate: Comparison between measurements and simulations Growth rate is difficult to measure as the instability is fast and losses occur quickly

Measured loss pattern Stable beam  Nb  [0; 6] & [6.3;7.6] 1010 p Unstable beam  Nb  [6; 6.3] 1010 p Unstable beam  Nb > 7.6 1010 p

Simulated loss patterns Stable beam  Nb  [0; 5] & [8;9] 1010 p Unstable beam  Nb  [5.5; 7.5] 1010 p Unstable beam  Nb > 9.5 1010 p

Measured loss pattern 0.2 sec 0.2 sec

Zbase TMCI in the SPS Impedance assessment See yesterday AB seminar from Rama