title: Controlling chaos in wave-particle interactions.
abstract: We analyze the behavior of a relativistic particle moving under the influence of a uniform magnetic field and a stationary electrostatic wave. We work with a set of pulsed waves that allows us to obtain an exact map for the system. We also use a method of control for near-integrable Hamiltonians that consists of the addition of a small and simple control term to the system. This control term creates invariant tori in phase space that prevent chaos from spreading to large regions, making the controlled dynamics more regular. We show numerically that the control term just slightly modifies the system but is able to drastically reduce chaos with a low additional cost of energy. Moreover, we discuss how the control of chaos and the consequent recovery of regular trajectories in phase space are useful to improve regular particle acceleration.
authors.affiliation: Instituto de Física, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: M C
authors.initials: MC
authors.lastname: de Sousa
authors.forename: I L
authors.initials: IL
authors.lastname: Caldas
authors.forename: F B
authors.initials: FB
authors.lastname: Rizzato
authors.forename: R
authors.initials: R
authors.lastname: Pakter
authors.forename: F M
authors.initials: FM
authors.lastname: Steffens
mesh_terms: D000054:Acceleration; D003198:Computer Simulation; D004574:Electromagnetic Fields; D005246:Feedback; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D011789:Quantum Theory