Yasushi Matsunaga

Evaluation of improved efficiency with a diamond coating for a plasma display panel electrode

Application of diamond to electrode coating of a plasma display panel (PDP) is evaluated, since we expect diamond to emit much secondary electron due to the Auger neutralization induced by Xe ions. In a conventional magnesium oxide-xenon (MgO/Xe) system, the most abundant Xe+ produced in the discharge does not effectively cause the secondary electron emission, because the condition of the Auger neutralization is not satisfied. In order to increase the efficiency of ultraviolet (UV) radiation, being especially important for engineering, we should avoid such inefficiency. Under suitable conditions in diamond/Xe system the Auger neutralization can occur. Further, if the electron affinity χ is negative, i.e., negative electron affinity (NEA), the condition of the Auger neutralization in diamond/Xe system is sufficiently satisfied. First, we calculate the coefficients of the secondary electron emission on diamond of clean surface or of hydrogenated surface where the dangling bonds are terminated, on the basis ...

Linear Response Theory Reformulated from the Chaotic Dynamics

Inadequacy of perturbation treatment in chaotic dynamics is pointed out, especially for phase space distribution function. The coarse graining is introduced into phase space distribution function for describing macroscopic thermodynamic process as a necessary and inevitable procedure for the transition from microscopic to macroscopic levels. A concept of convergence in law is employed for coarse graining. Thus a new approach to the linear response theory is presented, which can remove the various difficulties in the conventional linear response theory. The derivation of the distribution function in the sense of convergence in law is left open, but it is expected that the principal results such as fluctuation-dissipation theorem, Kubo formula for kinetic coefficient remain valid, provided that an appropriate interpretation is applied. Furthermore the entropy is shown to increase and the susceptibility derived in this theory is adiabatic susceptibility expected as a thermodynamic process. The present formul...

Analysis of Nonlinear Oscillation in Gas Discharge

Nonlinear oscillation that indicates chaotic behavior at low frequency in a gas discharge plasma is investigated by analytic and numerical solutions. The electric field in plasma is determined through the Poisson equation by assuming charge distribution: ions distribute spatially uniform, beam electrons from hot cathode are described by an exponentially decreasing distribution, and plasma electrons are in thermal equilibrium and described by the Boltzmann distribution. The electrostatic potential that is obtained analytically by using linear approximation contains the Debye shielding effect. Low frequency motion of the ions in this electric field is calculated numerically. Period-doubling bifurcation and chaotic oscillation are obtained for a region of parameters and they agree with the experimental results qualitatively.

Simple Model Analysis of Hysteresis Phenomenon of Gas Discharge Plasma

The hysteresis and multiple-steady states of gas discharge plasma are analyzed by a simple model of chemical-reaction system. In our analysis the emergence of multiple-steady states is explained by using a fact that a function describing the energy balance has three different real roots. The condition that the function has three roots depends on the ratio of the bulk energy increase to the surface energy loss of plasma. The criterion of taking place of the jump between two steady states is examined in a similar manner to order-disorder transition. The critical parameter contains the non-thermodynamic variables such as conductivity and surface quantities. Stabilities of three obtained solutions are discussed by using linear analysis of differential equations and we find that a root represents a saddle point and other two roots represent stable points. The first step to explain the hysteresis phenomenon in Ar gas discharge plasma is found.

THERMODYNAMIC TIME ASYMMETRY AND NONEQUILIBRIUM STATISTICAL MECHANICS

A review of recent advances in nonequilibrium statistical mechanics is presented. These new results explain how the time reversal symmetry is broken in the statistical description of nonequilibrium processes and the thermodynamic entropy production finds its origin in the time asymmetry of nonequilibrium fluctuations. These advances are based on new relationships expressing the time asymmetry in terms of the temporal disorder and the probability distributions of nonequilibrium fluctuations. These relationships apply to driven Brownian motion and molecular motors.

Kinetic simulation of nonlinear phenomena of an ion acoustic wave in gas discharge plasma with convective scheme

Nonlinear phenomena of the ion acoustic wave in a negatively charged plasma–sheath system are observed in the simulation with a convective scheme described by a two-dimensional phase space, and are theoretically analyzed. Subharmonics of a fundamental mode are excited and show the bifurcation phenomena when the intensity of the ion source relating to the ionization is increased. A reversed electric field from the cathode to anode reveals that the ponderomotive force due to a high frequency mode pushes the ions toward the cathode. A nonlinear coupling of two modes through the ponderomotive force is a key idea to construct the model. Nonlinear dynamical model equations involving the coupling of the two modes and an interaction of the sheath with the two modes, i.e., two nonlinear effects, are proposed. The period-doubling bifurcations of the fundamental mode are examined by using the same growth rates with the flow velocity as in our previously published linear theory.

Kinetic simulation on ion acoustic wave in gas discharge plasma with convective scheme

In a one-dimensional plasma-sheath system representing a concave quasistationary electric potential typical of a negatively charged system, oscillations of ion are simulated by the aid of a convective scheme useful for weakly ionized plasma, and are theoretically investigated. The frequency spectra of the ion current through a cathode reveal to us that two modes of ion acoustic waves are dominant; a high and a low frequency mode. By deriving a linear differential equation with a dissipation and an ion flow, and taking for granted the sheath width and the distribution of ion flow velocity, the dispersion relation for a finite length system can be calculated. The simulation results, such as the reinforcement of the low frequency mode and the suppression of the high frequency mode, are satisfactorily corroborated by the linear theory. The instabilities of the waves are caused by the asymmetry of boundary conditions and by the dissipative effect.

A Landau mode in current-carrying carbon nanotube and effects on electrical breakdown

On the basis of the Landau quantization, the bound state is discussed, which includes the finite length effect, induced magnetic field, and electric field in a current-carrying nanotube. Using a slab model and evaluating the matching of the wave function in the radial direction, the authors obtained the conditions of a Landau mode in which the momentum in the axial direction is reversed in the outer side and inner side of the nanotube shell. The mode arises over a threshold electric current, influences more long tubes than short tubes, and does not contribute to the net electric current. The authors compared the theoretical results to the experimental data, estimating the minimum voltage condition, the relations between the tube length and the current for the obtained Landau mode, and the tube length and current data in the experiments. It is plausible that the Landau mode plays an important role in the eventual electrical breakdown and the thinning phenomena. The wave function broadly spreading in the ou...

Selective production of armchair-type carbon nanotubes

The controllability and promotion of the production of metallic nanotubes by imposing an external electric field are examined based on a numerical simulation. The electronic states of the π electrons are described by the Huckel method and their electric interactions are self-consistently taken into account through the Poisson equation. The frontier electron density at both ends of the nanotubes with open ends is evaluated. For armchair tubes, the frontier electron density at both ends becomes a maximum near the electric field of 1 V/nm. The ratio of the frontier density of the armchair tubes to zigzag tubes is 3:1 near this electric field. The frontier density for zigzag tubes shows a maximum in the absence of an external electric field, while, by imposing an electric field, the frontier density decreases. The optimal intensity of a direct current electric field to efficiently make metallic nanotubes is determined.

Kinetic Simulation of an Ion Acoustic Wave with Charge Exchange Process in Direct Current Discharge Plasma

A charge exchange model is set and its simulation results are compared to those of previous friction model in the lower current branch of a discharge plasma. A remarkable delocalization of a high f...