Influence of Incident Velocity on the Penetration for C20 Clusters Moving through Oxides

A theoretical model is established to simulate the penetration process of C20 clusters in oxides （Al2O3, SiO2） at different incident velocities. The induced spatial potential by the incident clusters is described by the dielectric response formalism, in which the Mermin-type dielectric function is adopted to provide a realistic evaluation of the electronic properties of the oxides. The charge distribution of individual ions is derived by using the Brandt-Kitagawa effective charge model, also under the consideration of the asymmetric influence from the wake potential. The stopping power of the clusters and the Coulomb explosion processes are derived by solving the motion equation of the individual ions, when taking into account the multiple scattering effect simulated by using the Monte Carlo method. It is found that the dynamical interaction potential between ions leads to a spatial asymmetry to the cluster structure and the charge distribution for high velocity clusters, and will not be in effect as the incident velocities decrease.

Self-consistent Kinetic Description of the Low-Pressure Solenoidal Inductively Coupled Argon Discharge

Using an one-dimensional slab model, we have studied the electron energy distribution, the anomalous skin effect, and power absorption in the solenoidal-inductively-coupled argon discharge under low pressures (≤ 1.33 Pa). The electron energy distribution function and rf electromagnetic field in the plasma are determined self-consistently by the linearized Bolztmann equation incorporating with the Maxwell equations. The numerical results show that, at low pressures, the electron energy distribution function exhibits a non-Maxwellian distribution with a long high-energy tail. The anomalous skin effect is greatly enhanced under low pressures and the negative power absorption is also obtained.

Interactions of a Charged Particle with Parallel Two-Dimensional Quantum Electron Gases

By using the linearized quantum hydrodynamic （QHD） theory, electronic excitations induced by a charged particle moving between or over two parallel two-dimensional quantum electron gases （2DQEG） are investigated. The calculation shows that the influence of the quantum effects on the interaction process should be taken into account. Including the quantum statistical and quantum diffraction effects, the general expressions of the induced potential and the stopping power are obtained. Our simulation results indicate that a V-shaped oscillatory wake potential exists in the electron gases during the test cha.rge intrusion. Meanwhile, double peaks will occur in the stopping power when the distance of two surfaces is smaller and the test charge gets closer to any one of the two sheets.

Coulomb Explosion and Energy Loss of Energetic C20 Clusters in Dense Plasmas

The molecular dynamics （MD） method is used to simulate the interactions of energetic C20 clusters with the dense plasma targets within the framework of the linear Vlasov-Poisson theory. The influences of various clusters （H2, N2, C20 and C60 respectively） on stopping power are discussed. The simulation results show that the vicinage effects in the Coulomb explosion dynamics and the stopping power are strongly affected by the variations in the cluster speed and the plasma parameters. Coulomb explosions are found to proceed faster for higher speeds, lower plasma densities and higher electron temperatures. In addition, the cluster stopping power is strongly enhanced in the early stages of Coulomb explosions due to the vicinage effect, but this enhancement eventually diminishes, after the cluster constituent ions are sufficiently separated. For the large and heavy clusters, the stopping power ratio reaches much higher values in the early stage of Coulomb explosion owing to the constructive interferences in the vicinage effect.

RF electric field penetration and power deposition into nonequilibrium planar-type inductively coupled plasmas

The RF electric field penetration and the power deposition into planar-type inductively coupled plasmas in low-pressure discharges have been studied by means of a self-consistent model which consists of Maxwell equations combined with the kinetic equation of electrons. The Maxwell equations are solved based on the expansion of the Fourier-Bessel series for determining the RF electric field. Numerical results show the influence of a non-Maxwellian electron energy distribution on the RF electric field penetration and the power deposition for different coil currents. Moreover, the two-dimensional spatial profiles of RF electric field and power density are also shown for different numbers of RF coil turns.