Sep 15 – 21, 2019
Hotel Hermitage, La Biodola Bay, Isola d'Elba, Italy
Europe/Rome timezone

Efficiency and beam quality in a loaded quasilinear plasma wakefield positron accelerator

Sep 17, 2019, 6:20 PM
SB2 (Hotel Hermitage)


Hotel Hermitage

talk WG8 - Advanced and novel accelerators for High Energy Physics WG8 - Positrons


Siyi Yu (Ecole Polytechnique)


Being promising alternatives to conventional accelerators and for application to high-energy physics also linear colliders, it is crucial for plasma accelerators to accelerate positrons, which is much more challenging than electron acceleration that most current researches focus on.

Plasma electron motion is one main source of beam quality degradation for positron acceleration in quasi-linear regime of plasma wakefield acceleration. We study the evolution of a positron witness bunch starting from matched condition in wakefield generated by a drive bunch. For relatively high witness charge, the witness projected emittance can initially grow and rapidly saturate due to non-linear transverse focusing force of loaded wakefield. But it is found that the relative emittance growth stays moderate and that negligible emittance growth occur after equilibrium reached. However, beam loading creates a longitudinal accelerating field that varies both longitudinally and transversely, and generates significant slice correlated energy spread, which grows continuously over propagation distance. The degradation of longitudinal phase space sets a limit on the witness charge that can be accelerated in quasilinear plasma wakefield, which also limits the efficiency of the accelerator. It is found that efficiencies of up to 20% can be obtained for a positron plasma wakefield accelerator in quasi-linear regime.

Primary author

Siyi Yu (Ecole Polytechnique)


Dr Gaurav Raj (Ecole Polytechnique) Dr Olena Kononenko (Ecole Polytechnique) Dr Pablo San Miguel Claveria (Ecole Polytechnique) Spencer Gessner (CERN) Sébastien Corde (Ecole Polytechnique)

Presentation materials