Controlling chaos in area-preserving maps

We describe a method of control of chaos that occurs in area-preserving maps. This method is based on small modifications of the original map by addition of a small control term. We apply this control technique to the standard map and to the tokamap

Long-time discrete particle effects versus kinetic theory in the self-consistent single-wave model

The influence of the finite number N of particles coupled to a monochromatic wave in a collisionless plasma is investigated. For growth as well as damping of the wave, discrete particle numerical simulations show an N-dependent long time behavior resulting from the dynamics of individual particles. This behavior differs from the one due to the numerical errors incurred by Vlasov approaches. Trapping oscillations are crucial to long time dynamics, as the wave oscillations are controlled by the particle distribution inhomogeneities and the pulsating separatrix crossings drive the relaxation towards thermal equilibrium.Comment: 11 pages incl. 13 figs. Phys. Rev. E, in pres

Dynamical Behaviour of a Plasma Discharge in the Current Regime Limited by the Cathode Temperature

Experimental observations of plasma self-oscillations are presented. In the current regime limited by the cathode temperature of a continuous multipolar discharge, they appear for low gas pressure (collisionless plasma), low cathode heating current and above a discharge voltage threshold. Their frequency and amplitude are strongly dependent on the discharge parameters. The scaling laws of their variation and an example of a period-doubling route to chaos are reported

Laser Induced Fluorescence Observation of the Ion Velocity Distribution Function Modifications Induced by Electrostatic Ion Shock Waves

Time resolution is added to a Laser Induced Fluorescence (LIF) diagnostic used to probe plasma ions. It is applied to investigate the effects induced by the propagation of electrostatic ion shock waves in a low density collisionless argon plasma. Preliminary results show the first LIF observation of the velocity distribution function of the “precursor” ions reflected by the shock front

Steady state behavior of a multipolar plasma device

International audienceA low pressure discharge plasma, with magnetic multipolar confinement, is produced in a cylindrical ultrahigh vacuum device. The device has been specially designed to allow both moving Langmuir probe measurements and laser induced fluorescence diagnostic for the plasma ions. It is well suited to explore the sheaths region in a bounded plasma and to study wave and turbulence in a laboratory plasma. The main characteristics of the experimental setup and of the produced plasma are described

Nonlinear Dynamics and Chaos in Gas Discharge Systems

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