Parametrization of nonlinear and chaotic oscillations in driven beam-plasma diodes

Nonlinear phenomena in a driven plasma diode are studied using a fluid code and the particle-in-cell simulation code XPDPI. When a uniform electron beam is injected to a bounded diode filled with uniform ion background, the beam is destabilized by the Pierce instability and a perturbation grows to exhibit nonlinear oscillations including chaos. Two standard routes to chaos, period doubling and quasiperiodicity, are observed. Mode lockings of various winding numbers are observed in an ac driven system. A new diagnostic quantity is used to parametrize various nonlinear oscillations.open10

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

International audienc