Development of the self-modulation instability of a relativistic proton bunch in plasma
Physics of Plasmas AIP Publishing 30 (2023) 083104
Abstract:
Self-modulation is a beam-plasma instability that is useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size of the bunch and the plasma skin depth, the instability occurs later along the bunch, or not at all, over a fixed plasma length, because the amplitude of the initial wakefields decreases. We show cases for which self-modulation does not develop and we introduce a simple model discussing the conditions for which it would not occur after any plasma length. Changing bunch size and plasma electron density also changes the growth rate of the instability. We discuss the impact of these results on the design of a particle accelerator based on the self-modulation instability seeded by a relativistic ionization front, such as the future upgrade of the AWAKE experiment.Quasi-Alvarez drift-tube linac structures for heavy ion therapy accelerator facilities
Physical Review Accelerators and Beams American Physical Society (APS) 26:2 (2023) 022001
Design of the proton and electron transfer lines for AWAKE Run 2c
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Elsevier 1049 (2023) 168094
Abstract:
The Advanced Wakefield (AWAKE) Run 1 experiment, which concluded in 2018, achieved electron acceleration to 2GeV via plasma wakefield acceleration driven by 400GeV, self-modulated proton bunches extracted from the CERN SPS. The Run 2c phase of the experiment aims to advance these results by demonstrating acceleration up to about 10GeV while preserving the quality of the accelerated electron beam. For Run 2c, the Run 1 proton transfer line will be reconfigured to shift the first plasma cell 40m longitudinally and a second plasma cell will be added 1m downstream of the first. In addition, a new 150MeV beamline will be required to inject a witness electron beam, with a beam size of several microns, into the second plasma cell to probe the accelerating fields. Proposed adjustments to the proton transfer line and the design of the 150MeV electron transfer line are detailed in this paper.The AWAKE Run 2 programme and beyond
Symmetry MDPI 14:8 (2022) 1680