Paper  Title  Page 

WEPPR024  Motion of Charged Particle Dense Bunch in Nonuniform External Fields  2985 


At the output of a linear resonance accelerator, a charged particle beam consists of a bunch series, with the relation between bunch length and transverse bunch size changing widely. It is of importance to describe bunch dynamics in a selfconsistent manner*,** . Usually the charged bunch is described as ellipsoid with uniform density. Such description allows easy consideration of its own bunch fields. In the case of a nonstationary distribution it is difficult to build distribution function describing 3Dellipsoid with uniform density** . In this paper such function is found for bunch formed as rotation ellipsoid. Radii ellipsoid equations are obtained for a bunch moving in nonuniform stationary external fields.
* A.S. Chikhachev. Kinetic theory of quasystationary state of charged particle beams. Moscow,2001. ** I.M. Kapchinsky. Theory of linear resonanse accelerators. Particle dynamics. Moscow,1982. 

WEPPR025  Effective Emittance Growth in Beam with Gaussian Density Profile  2988 


In a continuous beam with nonuniform charge density profile transverse oscillations are nonlinear resulting in effective emittance growth. It is of great practical interest to find this growth scaling law in the case of beam with Gaussian density distribution. To study the effect for a sheet beam with parabolic density profile, a fully kinetic and selfconsistent model was built. The model allows one to obtain equations for envelope radius and rms emittance in a selfconsistent manner, as the KVmodel does it. The only model requirement is a special type of distribution function depending on the integral of nonlinear motion equations that automatically satisfies the Vlasov equation. The envelope equation is proved to be an ODE of 4th order. It was solved by the RungeKutta method. The beam parameter range was found where rms emittance growth is absent. The stationary equilibrium solution was found, too. The stability of solutions near equilibrium one was studied. An analysis of results shows that when there is no energy dissipation in the channel, rms emittance rises due to phase mixing between envelope oscillations and density distribution shape oscillations.  