Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

Abstract

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton

Electron beam characterization with beam loss monitors

“…AWAKE [1], the Advanced WAKEfield experiment at CERN, recently demonstrated acceleration of externally injected electrons in plasma wakefields resonantly excited by a self-modulated [2] [3] relativistic proton bunch [4].…”

Accelerating field enhancement due to ion motion in plasma wakefield accelerators

“…The effect of wakefield enhancement was first noticed in numerical simulations of the AWAKE experiment. In AWAKE [18][19][20], a long proton bunch undergoes seeded self-modulation in the plasma [21][22][23] and transforms into a train of short micro-binches that resonantly drive the plasma wave [24,25]. The number of micro-bunches depends on the plasma density and is typically about one hundred, so the plasma wave exists sufficiently long to move the ions.…”

A compact electron injector for the EIC based on plasma wakefields driven by the RHIC-EIC proton beam

“…Proton beams that are produced at accelerator facilities typically have small transverse sizes (σ r ∼ 100 µm) but are long (σ z ∼ 10 cm) and therefore do not appear to be suitable as drive beams for PWFA. However, it is possible to take advantage of an intrinsic plasma response to a long drive beam known as self-modulation that acts to split it into a series of microbunches [3], as demonstrated in Figure 1.…”