Accession Number : AD0474598


Title :   THE INSTABILITY OF CENTRIFUGAL- ELECTROSTATIC-FOCUSED FLOW.


Descriptive Note : Research rept.,


Corporate Author : CALIFORNIA UNIV BERKELEY ELECTRONICS RESEARCH LAB


Personal Author(s) : Lundgren, Ronald


Report Date : 23 Sep 1965


Pagination or Media Count : 102


Abstract : The stability of thin centrifugal- electrostatic-focused (CEF) streams is investigated. It is found that these streams can be unstable for axially asymmetric perturbations, but that perturbation growth stops or is severely damped after the beam attains some specific thickness. Linear analysis of the thin stream model shows that it is usually unstable for two-dimensional perturbations, with exponential time growth dependent on the azimuthal wave number. Moving the coaxial focusing walls closer to the stream first causes the growth rate at small n to decrease, then vanish, and finally to reappear accompanying a stream-image charge instability. The physical mechanism of growth is examined in detail and compared to its dual, the magnetically focused model of Kyhl-Webster-Pierce. The large-amplitude growth region is examined by numerical integration using a two-dimensional charged-rod model. The accuracy of the numerical method is checked against the results of a single-rod small-amplitude analysis. Starting points for the non-linear calculations are small density perturbations for n = 5, and 15 = 30. Growth of the stream thickness is exponential for approximately one or two stream revolutions, then quickly limits, going to a much slower or zero growth rate. (Author)


Descriptors :   *ELECTRON BEAMS , AXISYMMETRIC FLOW , ELECTROSTATIC FIELDS , STABILITY , FOCUSING , ELECTRON DENSITY , MAGNETIC FIELDS , EQUATIONS OF MOTION , PARTICLE TRAJECTORIES , MATHEMATICAL ANALYSIS


Subject Categories : Electricity and Magnetism


Distribution Statement : APPROVED FOR PUBLIC RELEASE