Computational investigation of dissipation and reversibility of space-charge driven processes in beams

Kishek, R. A.; Bohn, C.L.; Haber, I.; O’Shea, P.G.; Reiser, M.; Kandrup, Henry E.

doi:10.1109/pac.2001.987456

Cited by 5 publications

(5 citation statements)

References 10 publications

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“…Their failure to reappear again would seem to reflect some collisionless process that, in effect, causes the particles to 'forget' their initial conditions. Detailed simulations using the particle-in-cell code WARP [36], which do an extremely good job of reproducing what is actually seen, demonstrate seemingly unambiguously that, because of the time-dependent space-charge potential, a large fraction of the particles in the beam experience the effects of strong, possible transient, macrochaos [37,38]. This is, e.g., evident from Fig.…”

Section: Similarities Between Galaxies and Nonneutral Plasmassupporting

confidence: 60%

Chaos and Chaotic Phase Mixing in Galaxy Evolution and Charged Particle Beams

Kandrup

2003

Galaxies and Chaos

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Abstract. This paper discusses three new issues that necessarily arise in realistic attempts to apply nonlinear dynamics to galaxy evolution, namely: (i) the meaning of chaos in many-body systems, (ii) the time-dependence of the bulk potential, which can trigger intervals of transient chaos, and (iii) the self-consistent nature of any bulk chaos, which is generated by the bodies themselves, rather than imposed externally. Simulations and theory both suggest strongly that the physical processes associated with galactic evolution should also act in nonneutral plasmas and charged particle beams. This in turn suggests the possibility of testing this physics in real laboratory experiments, an undertaking currently underway.

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Section: Similarities Between Galaxies and Nonneutral Plasmassupporting

confidence: 60%

Chaos and Chaotic Phase Mixing in Galaxy Evolution and Charged Particle Beams

Kandrup

2003

Galaxies and Chaos

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“…Performing honest N -body integrations of interacting systems for very large N is not viable using current computational resources. However, fully self-consistent grid code simulations of intense charged beams have been found to exhibit both regular and chaotic phase mixing qualitatively similar to what has been found in smooth two-and three-dimensional potentials [4,22].…”

Section: Introductionsupporting

confidence: 56%

“…However, there is emerging evidence that, in at least some settings relevant to galactic astronomy [3] and accelerator dynamics [4], one is confronted with strongly nonintegrable chaotic dynamics. The manifestations of phase mixing in chaotic systems are very different from those in nearly integrable systems [5], a fact which has led galactic astronomers to speak of a new phenomenon called chaotic mixing [6].…”

Section: Introductionmentioning

confidence: 99%

Phase Mixing in Unperturbed and Perturbed Hamiltonian Systems

Kandrup

Novotny

2004

Celestial Mechanics and Dynamical Astronomy

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This paper summarises a numerical investigation of phase mixing in time-independent Hamiltonian systems that admit a coexistence of regular and chaotic phase space regions, allowing also for low amplitude perturbations idealised as periodic driving, friction, and/or white and colored noise. The evolution of initially localised ensembles of orbits was probed through lower order moments and coarse-grained distribution functions. In the absence of time-dependent perturbations, regular ensembles disperse initially as a power law in time and only exhibit a coarse-grained approach towards an invariant equilibrium over comparatively long times. Chaotic ensembles generally diverge exponentially fast on a time scale related to a typical finite time Lyapunov exponent, but can exhibit complex behaviour if they are impacted by the effects of cantori or the Arnold web. Viewed over somewhat longer times, chaotic ensembles typical converge exponentially towards an invariant or near-invariant equilibrium. This, however, need not correspond to a true equilibrium, which may only be approached over very long time scales. Time-dependent perturbations can dramatically increase the efficiency of phase mixing, both by accelerating the approach towards a near-equilibrium and by facilitating diffusion through cantori or along the Arnold web so as to accelerate the approach towards a true equilibrium. The efficacy of such perturbations typically scales logarithmically in amplitude, but is comparatively insensitive to most other details, a conclusion which reinforces the interpretation that the perturbations act via a resonant coupling. PACS number(s): 05.60.+w, 05.40.+j, 51.10.+y, 98.10.+z

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“…Recently, we have begun to take advantage of the close connection between galactic dynamics and chargedparticle-beam dynamics 3 to explore the correspondences and the possibility of setting up beam experiments to investigate questions in galactic dynamics. 4,5 This paper describes the University of Maryland electron ring (UMER), the facility on which we intend to perform such experiments.…”

Section: Introductionmentioning

confidence: 99%

The University of Maryland Electron Ring: A Platform For Study of Galactic Dynamics on a Laboratory Scale

Kishek

O’Shea

Bernal

et al. 2005

Annals of the New York Academy of Sciences

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The University of Maryland electron ring (UMER) is a novel experimental storage ring designed to investigate the dynamics of large systems of collisionless particles that nevertheless interact via collective mechanisms. Heavily diagnosed and designed to circulate a 100 mA electron beam at 10 keV for several turns, UMER allows us to follow the evolution of the beam over a large number of dynamical periods. Given the similarity of dynamics between the Coulomb forces and gravitational forces, it is possible to design beam experiments that will simulate such astrophysical events as galactic merger, for instance. The cross-comparison of beam experiments with accelerator simulation codes provides invaluable benchmarks of transient processes akin to, for example, violent relaxation in stellar systems that are otherwise impossible to obtain.

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Computational investigation of dissipation and reversibility of space-charge driven processes in beams

Cited by 5 publications

References 10 publications

Chaos and Chaotic Phase Mixing in Galaxy Evolution and Charged Particle Beams

Chaos and Chaotic Phase Mixing in Galaxy Evolution and Charged Particle Beams

Phase Mixing in Unperturbed and Perturbed Hamiltonian Systems

The University of Maryland Electron Ring: A Platform For Study of Galactic Dynamics on a Laboratory Scale

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