Navegação Ciências Exatas e da Terra por Autor "Pakter, Renato"
Resultados 1-20 de 64
-
Adiabatic-nonadiabatic transition in warm long-range interacting systems : the transport of intense inhomogeneous beams
(2012) [Artigo de periódico]We investigate the role of the temperature in the onset of singularities and the consequent breakdown in a macroscopic fluid model for long-range interacting systems. In particular, we consider an adiabatic fluid description ... -
Alternate islands of multiple isochronous chains in wave-particle interactions
(2013) [Artigo de periódico]We analyze the dynamics of a relativistic particle moving in a uniform magnetic field and perturbed by a standing electrostatic wave. We show that a pulsed wave produces an infinite number of perturbative terms with the ... -
An analytical model to determine equilibrium quantities of azimuthally symmetric and mismatched charged particle beams under linear focusing
(2008) [Artigo de periódico]The model developed here analytically allows to obtain equilibrium quantities of interest from high-intensity charged particle beams such as the emittance, beam envelope, and the number of beam halo particles. The results ... -
Bifurcations leading to stochasticity in a cyclotron-maser system
(1994) [Artigo de periódico]This paper is concerned with the orbital dynamics of electrons in a cyclotron maser [CO Chen, Phys. Rev. A 46,6654 (1992)] with modulated maser fields. Amplitude modulation is a natural result of wave-particle energy ... -
Centroid motion in periodically focused beams
(2005) [Artigo de periódico]The role of the centroid dynamics in the transport of periodically focused particle beams is investigated. A Kapchinskij–Vladimirskij equilibrium distribution for an off-axis beam is derived. It is shown that centroid and ... -
Chaos and coherence in the conservative three-mode decay interaction
(2000) [Artigo de periódico]In this work we analyze the influence of chaos on the coherence of the mismatched three-wave interaction. Chaos starts to play a decisive role in the problem when adiabatic approximations leading to an integrable model for ... -
Chaos and relaxation to equilibrium in systems with long-range interactions
(2015) [Artigo de periódico]In the thermodynamic limit, systems with long-range interactions do not relax to equilibrium, but become trapped in nonequilibrium stationary states. For a finite number of particles a nonequilibrium state has a finite ... -
Chaotic dynamics induced by space-charge waves in cyclotron resonance accelerators
(1996) [Artigo de periódico]In this work, we analyze the effects produced by the inclusion of space-charge waves in a Hamiltonian model for a cyclotron resonant accelerator. We find that space charges impose limits on acceleration and that these ... -
Chaotic particle heating due to an obliquely propagating wave in a magnetized plasma
(2013) [Artigo de periódico]We study the dynamics of a relativistic charged particle in the presence of a uniform magnetic field and a stationary electrostatic wave that propagates at an arbitrary angle. The wave is considered as a series of periodic ... -
Coherence–incoherence transition in nonlinear wave interactions
(2005) [Artigo de periódico]In this paper we analyze the transition from coherent to incoherent wave dynamics in a broad-band triplet interaction, where, in contrast to previous models, wave vector selection rules are imposed on the nonlinear terms ... -
Cold-fluid equilibrium for a corkscrewing elliptic beam in a variably focusing channel
(2000) [Artigo de periódico]It is shown that there exists a new class of cold-fluid corkscrewing elliptic beam equilibria for ultrahigh-brightness, space-charge-dominated beam propagation through a linear focusing channel consisting of uniform ... -
Collisionless relaxation in gravitacional systems from violent relaxation to gravothermal collapse
(2008) [Artigo de periódico]Theory and simulations are used to study collisionless relaxation of a gravitational N-body system. It is shown that when the initial one-particle distribution function satisfies the virial condition—potential energy is ... -
Collisionless relaxation in non-neutral plasmas
(2008) [Artigo de periódico]A theoretical framework is presented which allows us to quantitatively predict the final stationary state achieved by a non-neutral plasma during a process of collisionless relaxation. As a specific application, the theory ... -
Combined centroid-envelope dynamics of intense, magnetically focused charged beams surrounded by conducting walls
(2006) [Artigo de periódico]In this paper we analyze the combined envelope-centroid dynamics of magnetically focused high-intensity charged beams surrounded by conducting walls. Similar to the case where conducting walls are absent, it is shown that ... -
Comment on "Thermostatistics of overdamped motion of interacting particles"
(2011) [Artigo de periódico] -
Controlling chaos in wave-particle interactions
(2012) [Artigo de periódico]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 ... -
Core-halo boundary in a sheet beam model
(2021) [Artigo de periódico]In this paper, halo formation in a sheet beam model is investigated. Special attention is given to the core-halo boundary. In particular, a the ory to determine the final stationary state achieved by an initially mismatched ... -
Core-halo distribution in the Hamiltonian mean-field model
(2011) [Artigo de periódico]We study a paradigmatic system with long-range interactions: the Hamiltonian mean-field (HMF) model. It is shown that in the thermodynamic limit this model does not relax to the usual equilibrium Maxwell-Boltzmann distribution. ... -
Correlation decay and partial coherence in nonlinear wave interactions
(2003) [Artigo de periódico]In the present analysis we study the broad-band triplet interaction in regimes of large amplitudes. Linear response theories associated with nonlinear arguments are used to show that even though coherence of highfrequency ... -
Driven one-component plasmas
(2009) [Artigo de periódico]A statistical theory is presented that allows the calculation of the stationary state achieved by a driven one-component plasma after a process of collisionless relaxation. The stationary Vlasov equation with appropriate ...
