Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Plasma Physics
Volume 57, Number 12
Monday–Friday, October 29–November 2 2012; Providence, Rhode Island
Session CI2: Beams and Coherent Radiation
2:00 PM–5:00 PM,
Monday, October 29, 2012
Room: Ballroom DE
Chair: Eric Esarey, Lawrence Berkeley National Laboratory
Abstract ID: BAPS.2012.DPP.CI2.3
Abstract: CI2.00003 : Self-modulated plasma wakefield accelerators*
3:00 PM–3:30 PM
Preview Abstract Abstract
Carl B. Schroeder
(Lawrence Berkeley National Laboratory)
A long, relativistic, particle beam propagating in an overdense plasma is subject to the self-modulation instability. This instability modulates the beam radius and density at the plasma wavelength, exciting a large plasma wave that potentially could be used for high-gradient acceleration of particle beams. Self-modulation of proton beams (such as those available at CERN) are actively being considered to drive compact plasma accelerators. The beam self-modulation instability is analyzed in homogeneous and inhomogeneous plasma. While undergoing modulation, the phase velocity of the plasma wave is significantly less than the beam velocity, which severely limits the energy gain of the accelerated electron beam. Tapering (i.e., a plasma density that increases along the direction of beam propagation) offers the possibility to compensate for the slow wave phase velocity, improving the efficiency of the accelerator, and the optimal form of the taper is presented. Small plasma density inhomogeneities may result in decoherence effects that will suppress the instability, making experimental realization challenging. The transverse stability of the drive beam (e.g., the growth of beam hosing) is a critical concern for beam-driven plasma wakefield accelerators, and, in particular, for long beams. Coupling of the beam envelope self-modulation to the beam centroid displacements (hosing) is described. Methods to mitigate hosing by seeding the self-modulation will be presented. Implications for proton-beam-driven plasma accelerator experiments will be discussed.
*Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.DPP.CI2.3
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