Influence of energy and axial momentum spreads on the cyclotron maser instability in intense hollow electron beams
The influence of energy and axial momentum spreads on the cyclotron maser instability in an intense hollow electron beam propagating parallel to a uniform axial magnetic field B/sub 0/e/sub z/ is investigated. The stability analysis is carried out within the framework of the linearized Vlasov--Maxwell equations. It is assumed that ..nu../gamma-circumflexvery-much-less-than1, where ..nu.. is Budker's parameter and gamma-circumflexmc/sup 2/ is the characteristic electron energy. Stability properties are investigated for the choice of electron distribution function in which all electrons have a step-function distribution in energy (H=..gamma..mc/sup 2/) and a step-function distribution in axial momentum (p/sub z/). The instability growth rate is calculated including the important stabilizing influence of energy spread (epsilon=..delta gamma..) and axial momentum spread (..delta..=..delta..p/sub z/). It is shown that a modest energy spread (epsilonapprox. = a few percent) is sufficient to stabilize perturbations with high magnetic harmonic number (s> or =2). Moreover, a relatively small axial momentum spread (..delta../mcapprox. =0.1) can easily stabilize perturbations with axial wavenumber satisfying vertical-barkc/..omega../sub c/vertical-bar> or approx. =0.2, for typical beam parameters of experimental interest.
- Research Organization:
- Naval Surface Weapons Center, White Oak, Silver Spring, Maryland 20910
- OSTI ID:
- 6044514
- Journal Information:
- Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 22:9; ISSN PFLDA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ANALYTICAL SOLUTION
BEAMS
BOLTZMANN-VLASOV EQUATION
CYCLOTRON INSTABILITY
DIFFERENTIAL EQUATIONS
DISPERSION RELATIONS
DISTRIBUTION FUNCTIONS
ELECTRON BEAMS
ENERGY RANGE
ENERGY SPECTRA
EQUATIONS
INSTABILITY
LEPTON BEAMS
MAGNETIC FIELDS
MAXWELL EQUATIONS
MOTION
NORMAL-MODE ANALYSIS
NUMERICAL SOLUTION
PARTICLE BEAMS
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
RELATIVISTIC RANGE
ROTATION
SPECTRA