Stable, tunable, quasimonoenergetic electron beams produced in a laser wakefield near the threshold for self-injection

Authors

Sudeep Banerjee, University of Nebraska-LincolnFollow
Serguei Y. Kalmykov, University of Nebraska-LincolnFollow
Nathan D. Powers, University of Nebraska-LincolnFollow
Grigory V. Golovin, University of Nebraska-LincolnFollow
Viswanathan Ramanathan, Rensselaer Polytechnic Institute
Nathaniel J. Cunningham, Nebraska Wesleyan UniversityFollow
Kevin J. Brown, University of Nebraska-LincolnFollow
Shouyuan Chen, University of Nebraska - LincolnFollow
Isaac A. Ghebregziabher, University of Nebraska - LincolnFollow
Bradley Allan Shadwick, University of Nebraska-LincolnFollow
Donald Umstadter, University of Nebraska-LincolnFollow
B. M. Cowan, Tech-X Corporation, Boulder, CO
D. Bruhwiler, University of Colorado at Boulder
A. Beck, CEA, DAM, DIF, Arpajon Cedex, France
E. Lefebvre, CEA, DAM, DIF, Arpajon Cedex, France

Date of this Version

2013

Citation

Phys. Rev. ST Accel Beams 16, 031302 (2013).

DOI: 10.1103/PhysRevSTAB.16.031302

Comments

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License.

Abstract

Stable operation of a laser-plasma accelerator near the threshold for electron self-injection in the blowout regime has been demonstrated with 25–60 TW, 30 fs laser pulses focused into a 3–4 millimeter length gas jet. Nearly Gaussian shape and high nanosecond contrast of the focused pulse appear to be critically important for controllable, tunable generation of 250–430 MeV electron bunches with a low-energy spread, ∼10  pC charge, a few-mrad divergence and pointing stability, and a vanishingly small low-energy background. The physical nature of the near-threshold behavior is examined using three-dimensional particle-in-cell simulations. Simulations indicate that properly locating the nonlinear focus of the laser pulse within the plasma suppresses continuous injection, thus reducing the low-energy tail of the electron beam.