Speaker
Description
The AWAKE experiment at CERN aims at driving plasma wakefields using a long, highly energetic (400GeV) proton bunch from the Super Proton Synchrotron, in principle enabling the acceleration of a witness bunch with a large gradient (>1GeV/m) over hundreds of meters. To drive these large amplitude wakefields, the long bunch must first be split into a train of microbunches through a transverse process, the self-modulation (SM) instability. High-gradient acceleration of a witness bunch can only occur after SM reaches saturation, making measurement of the saturation length crucial for the design of an SM-based accelerator.
We show that, by varying the plasma length and measuring the transverse profile of the bunch at a downstream screen, we directly observe for the first time the development of SM along the plasma. From these measurements, we determine the saturation length of SM, and study its dependence on key parameters, i.e., plasma density and initial wakefield amplitude.
In addition, and by using two independent diagnostics, we show that seeding makes the SM process reproducible from event to event, an essential requirement for producing a high-quality accelerated electron bunch.
We will introduce the AWAKE experiment, present these experimental results and their implications for long-term plans.
| Working group | WG3 |
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