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Title: Kinetic description of the sideband instability in a helical-wiggler free-electron laser

Journal Article · · Phys. Fluids; (United States)
DOI:https://doi.org/10.1063/1.865511· OSTI ID:5657534

The Vlasov--Maxwell equations are used to investigate properties of the sideband instability for a tenuous, relativistic electron beam propagating in the z-italic direction through a constant-amplitude helical-wiggler magnetic field B/sub w-italic/(x) = B-italic-circumflex/sub w-italic/(cos k-italic/sub 0/ z-italice-circumflex/sub x-italic/+sin k-italic/sub 0/ z-italice-circumflex/sub y-italic/). The theoretical model neglects longitudinal perturbations (deltaphiapprox. =0) and transverse spatial variations (partial/partialx-italic = 0 = partial/partialy-italic). Moreover, the analysis is carried out for perturbations about an equilibrium BGK state in which the distribution of beam electrons G-italic/sub s-italic/(..gamma..') and the wiggler magnetic field (normalized amplitude a-italic/sub w-italic/ = e-italicB-italic-circumflex/sub w-italic//m-italicc-italic/sup 2/k-italic/sub 0/) coexist in quasisteady equilibrium with a finite-amplitude, circularly polarized, primary electromagnetic wave (..omega../sub s-italic/,k-italic/sub s-italic/) with normalized amplitude a-italic/sub s-italic/ = e-italicB-italic-circumflex/sub s-italic//m-italicc-italic/sup 2/k-italic/sub s-italic/.

Research Organization:
Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
OSTI ID:
5657534
Journal Information:
Phys. Fluids; (United States), Vol. 29:8
Country of Publication:
United States
Language:
English