Analysis of radiation focusing and guiding in the free-electron laser by use of a source-dependent expansion. Interim report

Technical Report · Mon Apr 20 00:00:00 EDT 1987

OSTI ID:6288653

Sprangle, P; Ting, A; Tang, C M

In the free-electron laser (FEL) the resonant interaction between the radiation field and electron beam can result in radiation focusing (optical guiding). If the centroid of the electron beam is transversely displaced off-axis, the radiation field, under certain conditions, will follow and be steered by the electron beam. The effect of a spatial modulation on the electron-beam envelope can also modify the propagation characteristics of the radiation. These and other phenomena are analytically and numerically studied using a novel source-dependent Laguerre-Gaussian modal representation of the fully three-dimensional radiation field. Unlike the vacuum Laguerre-Gaussian modal expansion, the longitudinal spatial dependence of the radiation waist and curvature are determined and characterized by the source term in the wave equation. Among the advantages of this general source-dependent-expansion (SDE) approach is that few modes are needed to accurately describe the radiation. Hence, fast and accurate numerical solutions of the fully three-dimensional FEL problem can be obtained over distances of many Rayleigh lengths. Furthermore, this expansion allows development of an envelope equation for the radiation beams as well as an expression for the centroid of the beam.

• Research Organization: Berkeley Scholars, Inc., CA (USA)
• OSTI ID: 6288653
• Report Number(s): AD-A-180923/5/XAB
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
FREE ELECTRON LASERS
FOCUSING
CONTROL
ELECTRON BEAMS
EXPANSION
INTERACTIONS
MODULATION
NUMERICAL ANALYSIS
RESONANCE
SPATIAL DISTRIBUTION
WAVE EQUATIONS
BEAMS
DIFFERENTIAL EQUATIONS
DISTRIBUTION
EQUATIONS
LASERS
LEPTON BEAMS
MATHEMATICS
PARTIAL DIFFERENTIAL EQUATIONS
PARTICLE BEAMS
420300* - Engineering- Lasers- (-1989)