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The space-dependent electron kinetics in the anode region of a cylindrical glow discharge is studied. In particular, the relevant Boltzmann equation of electrons is solved in two space dimensions to reveal the formation of the electron kinetic properties in the radial and axial directions. The solution method is based on a two-term expansion of the velocity distribution and the introduction of a total energy coordinate. The space-dependent description allows the investigation of the influence of electron absorption at the anode as well as the impact of anode fall on the spatial structure of the electron kinetic properties. The impact of radial space-charge confinement and its modification is studied in the transition region from the radially inhomogeneous positive column to the equipotential anode surface. A rigorous kinetic description allows among others the determination of axial and radial particle and energy fluxes of electrons in the anode region. Results are presented for a neon discharge at a pressure of about half a Torr.

Two-particle (exciton) states in equilibrium electron-hole plasmas of highly excited semiconductors are determined. In the framework of the Green's function technique, an effective (two-particle) wave equation allows to account for the influence of the surrounding plasma in terms of (dynamic) single-particle self-energies, Pauli blocking factors, and a dynamic effective potential correction. This equation is solved by expansion of the wave function in terms of Coulomb eigcnfimctions. No rational or pole approximation for the dielectric function is used. Exciton binding mcrgics and their imaginary parts (damping of the states) as well as continuum edges are given for Ge and GaAs model systems.Es werden Zwei-Teilchen-(Exzitonen-)Zustande in Elektron-Loch-Gleichgewichtsplasmen in hochangeregten Halbleitern bestimmt. Im Rahmen der Green-Funktionstechnik kann in einer effektiven (Zwei-Teilchen-) Wellengleichung der EinfluB des umgebenden Plasmas durch (tlynarnische) Ein-Teilchen-Selbstenergien, Phasenraumverbrauchsfaktoren und eine dynamische effektive Potcntialkorrektur beriicksichtigt werden. Diese Gleichung wird mittels Entwicklung der Wellenfunktion nach Coulomb-Eigenfunktionen gelost. Eine rationale oder Pol-Naherung fur die diclektrische Furiktion wird nicht verwendet . Exzitonen-Bindungsenergien und ihre Imaginarteile (Dampfung der Ziistande) sowie Kontinuumskanten werden fur ein Ge-und ein GaAs-Iblodellsystein angegeben.

The response of a neon glow discharge plasma on a disturbance caused by a floating Langmuir probe is studied by a fully self-consistent, spatially one-dimensional hybrid method as well as by measurements. The theoretical description is based on the coupled solution of the hydrodynamic equations of electrons, ions, and excited atoms and the Poisson equation. The space-dependent transport and rate coefficients of the electron component are determined by a strict solution of the non-uniform electron kinetic equation. For the measurements, a probe was inserted in radial direction into the discharge several cm in front of the anode. The spatial evolution of the densities of the excited atoms in the 1s 3 , 1s 5 , and 2p 8 states was determined by spectroscopic methods. Pronounced modulations of basic plasma parameters have been observed around the probe, decaying periodically and damped toward the anode. The measured density profiles of the excited atoms agree well with the numerically determined ones. The analysis of the electron kinetic quantities shows that the response of the plasma to the disturbance is widely determined by the nonlocal behaviour of the electrons in the distinctly disturbed electrical field.

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A neural network which models multistable perception is presented. The network consists of sensor and inner neurons. The dynamics is established by a stochastic neuronal dynamics, a formal Hebb-type coupling dynamics and a resource mechanism that corresponds to saturation effects in perception. From this a system of coupled differential equations is derived and analyzed Single stimuli are bound to exactly one percept, even in ambiguous situations where multistability occurs. The network exhibits discontinuous as well as continuous phase transitions and models various empirical findings, including the percepts of succession, alternative motion and simultaneity, the percept of oscillation is explained by oscillating percepts of a continuous phase transition.

A brief introduction into the progress of the analysis of the electron kinetics in spatially one-and two-dimensional steady-state plasmas and in spatiotemporal transition processes of spatially one-dimensional plasma configurations is given. The wide spectrum of the involved kinetic problems is briefly characterized, main aspects of its kinetic studies are outlined and the progress reached in recent years is illustrated by the kinetic study and deduced results of some selected problems.