skip to main content

SciTech ConnectSciTech Connect

Title: Enhancement of laser-driven electron acceleration in an ion channel

A laser beam with duration longer than the period of plasma oscillations propagating through an underdense plasma produces a steady-state positively charged channel in the electron density. We consider a test electron in the two-dimensional plane channel under the combined action of the laser field and the transverse static electric field of the channel. At ultrarelativistic laser wave amplitude (a≫1), the electron is pushed primarily forward. As the electron gradually dephases from the wave, the field it samples and its relativistic γ-factor strongly oscillate. The natural frequency of electron oscillations across the channel (betatron frequency) depends on γ, which couples the betatron oscillations to the longitudinal motion induced by the wave. We show that the modulation of the natural frequency makes the oscillations unstable. The resulting amplification of the oscillations across the channel reduces the axial dephasing between the electron and the wave, leading to a considerable electron energy enhancement well above the ponderomotive energy. We find that there is a well-pronounced laser amplitude threshold a{sub *}, above which the enhancement takes place, that scales as a{sub *}∝1/√(n{sub 0}), where n{sub 0} is the ion density. The presented mechanism of energy enhancement is robust with respect to a longitudinal variationmore » of the density, because it relies on a threshold phenomenon rather than on a narrow linear resonance.« less
Authors:
;  [1] ;  [2]
  1. Institute for Fusion Studies, The University of Texas, Austin, Texas 78712 (United States)
  2. Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
Publication Date:
OSTI Identifier:
22251958
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BETATRON OSCILLATIONS; BETATRONS; ELECTRIC FIELDS; ELECTRON DENSITY; ELECTRONS; LASER RADIATION; LASERS; PLASMA WAVES; PONDEROMOTIVE FORCE; RELATIVISTIC RANGE; STEADY-STATE CONDITIONS