Anode spot plasma deposition of insulating layers on aluminum

The deposition of an insulating layer upon an aluminum plate in an argon plasma is described. The process is effected in a low-power DC discharge to which a small amount of sulfur hexafluoride (SF₆) has been added, causing the formation of anode spots at sharp metallic surfaces. The insulator is deposited in the region beneath the spot     

On a solution to the single-mode model of superradiance

A self-similar solution of the diffusion equation for the atomic quasi-probability function discussed by Narducci and Bluemel is derived.     

A two-dimensional soliton in a positive ion-negative ion plasma

The authors describe a series of experiments performed in a positive ion-negative ion plasma that were designed to study the reflection and focusing properties of solitons. The nonlinear wave was compared with a theoretical model using linear waves. The two-dimensional soliton was created by reflecting an incident planar soliton from a concave hemispherical surface. The experimental results are interpreted in terms of the linear waves that can exist in a focused Fabry-Perot resonator     

On the soliton,invariant, and shock solutions of a fourth-order nonlinear equation

A particular transmission line containing a nonlinear capacitance is shown to satisfy the equation V_xxtt + ω₀²V_xx ? C_s^?1[VC_n(V)]_tt = 0, ω₀² = (LC_S)^?1. This equation is shown to permit the propagation of solitary waves (solitons). In addition, it admits an invariant (similar) solution under the spiral group. Lastly, we demonstrate two implicit traveling wave solutions that permit the evolution of a discontinuity in the first derivatives (shocks).     

Expansion of an Ion Sheath into a Collision-Dominated Plasma

If a large negative voltage is applied to an insulated disc inserted in a collision-dominated plasma, the electrons are expelled from the region near the disc leaving a bare cloud of ions. This "transient sheath" is well documented in ion acoustic wave experiments. This paper examines the evolution of the ions in this sheath into a collision-dominated plasma. A new sheath whose dimension is of the order of twice the transient sheath dimension if found.     

Extracting double layer charge density distributions using themethod of moments

Using the method of moments, it is shown that the charge distribution can be directly extracted from a measured potential profile. The technique is described and placed on a theoretical foundation. The predicted charge distribution for a potential profile V=V₀ tanh (x/L) using this technique is compared with a direct solution of Poisson's equation. It is shown that similar results are obtained even if random noise is present in the system     

Experimental Technique to Measure Phase-Space Diagrams in Plasma Experiments

An experimental technique is described which allows one to easily measure and rapidly display the particle distribution function in phase-space in nonlinear wave-plasma interaction experiments. An application to the study of Pseudowaves is also presented.     

Synchronization of the coupled FitzHugh–Nagumo systems

Buri and Todorovi recently studied the coupling of FitzHugh–Nagumo equations that can be used to describe neurological signal propagation. Using techniques from modern control theory, a nonlinear controller is obtained that results in two of the Buri and Todorovi systems being synchronized with each other. The detailed derivation that leads to the controller and numerical results that verify the controller’s ability to synchronize the two systems together are included.     

Radiation of ion acoustic waves in a dispersive positiveion-negative ion plasma

Experimental results that illustrate some properties of the radiation of a longitudinal ion acoustic wave launched from a solid metal disk antenna inserted in a dispersive positive-ion-negative-ion plasma are presented. The negative ions replace the free electrons in the plasma and increase the electron Debye length, hence increasing the dispersion of the plasma. It is observed that the radiation of waves in a dispersive media is significantly more complicated than in a nondispersive media. It is not possible to draw one universal radiation pattern for the radiation of the waves in this case, since so many frequency components are present in the wave and they change as the wave evolves