Electron Destruction Research Articles

Two-Dimensional Numerical Study on Characterization of Low-Pressure Capacitively Coupled Argon Discharges

This paper presents an investigation of argon capacitively coupled plasma at low pressure. A two-dimensional, time-dependent fluid model is used to describe the production, transport, and destruction of electrons and positive ions. The model is solved for a GEC(gaseous electronics conference) Cell reactor type (with 4cm diameter and 2.5cm interelectrode distance) operating at frequency 13.56MHz, pressure 1Torr and applied voltage 1000V, in pure argon. Two-dimensional distributions are presented in the stationary state, including electron temperature and species density i.e. electron, ion and metastable atom. The electric field and electric potential at different phases in one RF cycle is also studied.

Systematic characterization of low-pressure capacitively coupled hydrogen discharges

This paper presents a systematic characterization of pure hydrogen capacitively coupled discharges, produced in a parallel plate cylindrical setup. A two-dimensional, time-dependent fluid model is used to describe the production, transport, and destruction of electrons and positive ions H+, H2+, and H3+, at different frequencies (13.56–60 MHz), pressures (0.2–8 Torr), rf applied voltages (50–450 V) and geometric dimensions (1.6–12.8 cm radii and 1.6–6.4 cm interelectrode distances). A good agreement is found between calculation results and experimental measurements for the coupled electrical power, the plasma potential, and the self-bias potential, at various frequencies and rf applied voltages. However, the model generally underestimates the electron density with respect to its measured values. The paper discusses different space-time events, such as the development of double-ionization structures or the occurrence of field inversion and field reversal phenomena. The dependencies on pressure and frequency of the time-average electric field distribution are analyzed and related to the electron displacement within space-charge sheaths. This study is later used to understand the variations of the hydrogen dissociation rate, with changes in discharge operating conditions. The influence of reactor dimensions on the spatial profiles of the plasma potential, the rf electric field, the electron density, and the electron mean energy are analyzed in terms of discharge symmetry. An investigation of the space-time averaged rf electric field variations, with changes in the applied voltage, pressure, and geometric dimensions is carried out. These variations are shown to follow a universal similarity curve, if an adequate normalization is used when plotting the rf electric field as a function of pressure. This innovative representation of rf discharges allows a univocal definition of a reactor working point, for given operating conditions.

Electron destruction in a fractionized system.

Several experimental techniques, such as photoemission, Compton scattering, and positron annihilation, use the excitation or destruction of an electron to measure the momentum distribution of the electrons. The structure in these momentum distributions that results from the Fermi surface of a Fermi liquid is well known, but structure can also arise from the electron correlations in a strongly correlated system. The momentum distribution of a highly correlated two-dimensional electron system in which the spin and charge degrees of freedom are decoupled is examined using, as a model system, a noninteracting spinon-holon description of the excitations of the two-dimensional Hubbard model.

Analytic and experimental electrical conductivity between the stratosphere and the ionosphere

Data on atmospheric conductivity obtained experimentally in the altitude region between 35 and 80 km by use of rocket-borne Gerdien condensers are presented. Analytic expressions based on ion equilibrium and ionization by cosmic rays only are derived for comparison. The experimental technique is described, and several factors that might influence the measurements are evaluated. There is good agreement between the measured and predicted values of negative conductivity at altitudes up to 50 km. Low conductivity values observed between 50 and 80 km are attributed to ionic diffusion to particulate matter, the reduction agreeing quantitatively with that calculated from present estimates of the radius and concentration of noctilucent cloud particles. It is suggested that meteoritic dust may be an important agent for electron destruction in the ionosphere.