Kinetic stability properties of an intense relativistic electron ring in a high-current betatron accelerator

Journal Article · Thu Aug 01 04:00:00 EDT 1985 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.865261· OSTI ID:5573116

Uhm, H S; Davidson, R C; Petillo, J J

The kinetic stability properties of an intense relativistic electron ringlocated at the midplane of an externally applied betatron field are investigatedwithin the framework of the linearized Vlasov--Maxwell equations, including the important influence of electromagnetic effects and surface-wave perturbations. Stability properties are calculated for eigenfrequency ..omega.. near harmonics of the relativistic cyclotron frequency ..omega../sub c/z in the applied betatron field. Making use of the large-aspect-ratio assumption (R/sub 0/>>a/sub c/), a closed algebraic dispersion relation is obtained for the longitudinal instability, assuming that the electron ring is located inside a perfectly conducting toroidal shell. Several points are noteworthy in this analysis. First, transverse electromagnetic effects can provide complete stabilization provided the ring current is sufficiently large. Second, for the case where there are no ions (f = 0) and the betatron focusing force exceeds the self-field defocusing force (2..omega../sup 2//sub ..beta../ = ..omega../sup 2//sub c/z -..omega../sup 2//sub P/b/..gamma../sup 2//sub b/ >0), it is found that stabilization occurs at sufficiently low transverse temperature of the beam electrons. Third, for the case where ..omega../sup 2//sub ..beta../ <0 and the transverse temperature of the beam electrons is sufficiently low, it is found that surface perturbations on the electron beam drive a radial kink instability.

• Research Organization: Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
• OSTI ID: 5573116
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 28:8; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200* -- Particle Accelerators-- Beam Dynamics
Field Calculations
&amp; Ion Optics
ACCELERATORS
ASPECT RATIO
BETATRONS
BOLTZMANN-VLASOV EQUATION
CYCLIC ACCELERATORS
CYCLOTRON HARMONICS
DIFFERENTIAL EQUATIONS
DISPERSION RELATIONS
DISTURBANCES
DYNAMICS
EIGENVALUES
ELECTROMAGNETIC FIELDS
ELECTRON RINGS
ENERGY RANGE
EQUATIONS
HARMONICS
INSTABILITY
MECHANICS
OSCILLATIONS
PARTIAL DIFFERENTIAL EQUATIONS
RELATIVISTIC RANGE