70 research outputs found
Transverse Optical Mode Patterns for an RF Excited Ar-He-Xe Laser
Transverse optical modes for an RF excited Ar-He-Xe laser are studied both experimentally and theoretically. A diffraction model for a waveguide with a nonsaturable gain and refractive index gradients placed between two plane mirrors is formulated. The effects of gain and diffraction index gradients and of diffraction in free space are evaluated for typical experimental conditions. A direct comparison between theoretical mode patterns and experimentally measured ones at distances of 17 and 114 cm from the output mirror demonstrated a satisfactory agreement for various laser wavelengths and gas mixture composition
A Monte Carlo simulation of ion transport at finite temperatures
We have developed a Monte Carlo simulation for ion transport in hot
background gases, which is an alternative way of solving the corresponding
Boltzmann equation that determines the distribution function of ions. We
consider the limit of low ion densities when the distribution function of the
background gas remains unchanged due to collision with ions. A special
attention has been paid to properly treat the thermal motion of the host gas
particles and their influence on ions, which is very important at low electric
fields, when the mean ion energy is comparable to the thermal energy of the
host gas. We found the conditional probability distribution of gas velocities
that correspond to an ion of specific velocity which collides with a gas
particle. Also, we have derived exact analytical formulas for piecewise
calculation of the collision frequency integrals. We address the cases when the
background gas is monocomponent and when it is a mixture of different gases.
The developed techniques described here are required for Monte Carlo
simulations of ion transport and for hybrid models of non-equilibrium plasmas.
The range of energies where it is necessary to apply the technique has been
defined. The results we obtained are in excellent agreement with the existing
ones obtained by complementary methods. Having verified our algorithm, we were
able to produce calculations for Ar ions in Ar and propose them as a new
benchmark for thermal effects. The developed method is widely applicable for
solving the Boltzmann equation that appears in many different contexts in
physics.Comment: 14 page
Phase-locked arrays of antiguides: analytical theory II
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