Mitigation of Electron Cloud Instabilities in the LHC using Sextupoles and Octupoles.

Coherent electron cloud instabilities pose a serious limitation for luminosity upgrades in the Large Hadron Collider (LHC) at CERN. In particular, when bunch spacings reach below 50 ns electron cloud formation is enhanced which in turn drives beam instabilities. The beam can be stabilised by shifting the tune and increasing the tune spread using sextupoles and octupoles, respectively. The resulting values for the chromaticity and the detuning parameters must be selected with care, however, in order not to run into head-tail instabilities or to considerably reduce the dynamic aperture, respectively. A simulation study has been launched to estimate the parameters necessary for stabilisation of the beam under the influence of electron clouds.