Improvement of electron beam quality in optical injection schemes using negative plasma density gradients

Journal Article · Wed Feb 15 04:00:00 EST 2006 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

DOI:https://doi.org/10.1103/PHYSREVE.73.0· OSTI ID:20778706

Fubiani, G; Esarey, E; Schroeder, C B; Leemans, W P ^[1]

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1. Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

Enhanced electron trapping using plasma density down-ramps as a method for improving the performance of laser injection schemes is proposed and analyzed. A decrease in density implies an increase in plasma wavelength, which can shift a relativistic electron from the defocusing to the focusing region of the accelerating wakefield, and a decrease in wake phase velocity, which lowers the trapping threshold. The specific method of two-pulse colliding pulse injector is examined in detail using a three-dimensional test particle tracking code. A density down-ramp with a change of density on the order of tens of percent over distances greater than the plasma wavelength leads to an enhancement of charge by two orders in magnitude or more, up to the limits imposed by beam loading. The accelerated bunches are ultrashort (fraction of the plasma wavelength--e.g., {approx}5 fs), high charge (>20 pC at modest injection laser intensity {approx}10{sup 17} W/cm{sup 2}), with a relative energy spread of a few percent at a mean energy of {approx}25 MeV, and a normalized root-mean-square emittance of the order of 0.5 mm mrad.

• OSTI ID: 20778706
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics Journal Issue: 2 Vol. 73; ISSN PLEEE8; ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAM INJECTION
BEAM-PLASMA SYSTEMS
ELECTRON BEAMS
ELECTRONS
FOCUSING
LASERS
MEV RANGE 10-100
PERFORMANCE
PHASE VELOCITY
PLASMA
PLASMA DENSITY
PULSES
RELATIVISTIC RANGE
TEST PARTICLES
THREE-DIMENSIONAL CALCULATIONS
TRAPPING
WAVELENGTHS