A V Dem'yanov

Multidimensional modeling of excimer laser

The full-detailed kinetic model of XeCl laser is developed, which includes self-consistent solution of the electron Boltzmann equation, taking into account the electron collisions both with other and with vibrationally and electronically excited particles as well as the system of equations of plasma chemical kinetics and radiation transfer. 1-D, 2-D and 3-D models are worked out by simplifying the full kinetic model. The approximate kinetics have been verified to agree well with the detailed kinetics for the conditions investigated. These models have been applied to describe the effects of nonuniform pumping and spatial distribution of plasma components on the laser characteristics. The 1-D model of the electric discharge-pumped excimer laser will be presented and the results of 3-D mathematical simulation of the e-beam pumped amplifier with a large aperture will be reported. This model includes 2-D Monte- Carlo simulation of the fast electron transport and 3-D calculation of the amplified spontaneous radiation transfer. The amplified beam intensity distribution is calculated and the optical quality of the output beam is estimated, taking into account the refraction index variation across the amplifier aperture. A fast procedure to find out the laser resonator parameters for the maximal efficiency will be proposed, including the effects of spatial nonuniformity of the active medium.

Oxygen assisted iodine atoms production in an RF discharge

Experiments and modeling of CH3I dissociation in the plasma generated by a 40 MHz RF discharge were performed. A discharge chamber of an original design, consisting of quartz tubes between two planar electrodes, permitted the production of iodine atoms with number densities up to 2×1016 cm-3. In this discharge chamber, contamination of the walls of the tubes did not hinder discharge stability, providing a good iodine production rate. Addition of oxygen into Ar:CH3I mixture resulted in a substantial increase in iodine extraction efficiency. When the discharge power reached 200 W, complete CH3I dissociation in a Ar:CH3I:O2 mixture was observed. The fraction of discharge power spent on iodine atom production at a 0.17 mmol/s CH3I flow rate was 16%.

Zero- and one-dimensional modeling of phenomena in XeCl laser discharge

A large volume XeCl discharge pumped laser is studied by using several self-consistent models differing for assumptions regarding vibrational kinetics of HCl in the discharge mixture, volume stability, and microarc formation. Volume stability is studied by modeling the discharge plasma as a parallel resistor network, while a single microarc is introduced as a further network element with zero surface. It is stated that only models including microinstabilities as well as an accurate description of HCl vibrational kinetics could be used for large volume XeCl laser devices.