Speaker
Ms
Anna-Maria Bachmann
(CERN)
Description
AWAKE develops a new plasma wakefield accelerator using the CERN SPS proton bunch as a driver. The proton bunch propagates through a 10m long rubidium plasma, induced by an ionizing laser pulse that also seeds the wakefields for the self-modulation instability (SMI). Current diagnostics for the occurrence of the SMI focus on the proton bunch.
The SMI transforms the bunch in a train with hundreds of bunchlets driving hundreds of plasma wave periods. We therefore investigate the possibility of measuring frequency modulation of a CW laser propagating perpendicularly to the wakefields to determine some of the wakefields characteristics. Wakefields period information will appear in the position of satellites in the laser beam spectrum, whereas wakefields amplitude information will be in the satellites intensity. Satellites at the harmonics of the plasma period would indicate nonlinear modulation of the plasma density and wakefields amplitude. Measuring the wakefields amplitude at two points of the plasma cell, near the plasma entrance and near the exit, would provide proof of the growth of the SMI.
Primary author
Ms
Anna-Maria Bachmann
(CERN)
Co-author
Prof.
Patric Muggli
(Max-Planck-Institut für Physik)
