The study of helium ionization process stability in the channel of plasma accelerator

Numerical study of the ionization process stability in a flow of ionizing helium in the channel of the quasi-stationary plasma accelerator is presented. The model of two-dimensional axisymmetric flows is based on the modified MHD equations for the multicomponent medium consisting of atoms, electrons, and multiply charged ions with different ionization multiplicity. The numerical model takes into account the electrical conductivity and thermal conductivity. Results of modeling of the ionizing gas flows and the integral characteristics of the radiation are presented. As a result of a series of calculations, the empirical condition for the stability of ionizing helium flows was obtained in terms of the experimentally measured parameters.

Influence of Ionizing Gas Flow on Structural Homogeneity of Type IV Silica Glass

Type IV silica glass is the key material in inertial navigation and optical field due to its high purity and unbroken structural network. Structural homogeneity of type IV silica glass, which is mainly affected by producing process, is one of the most important properties and determines its usability. The influence of ionizing gas flow of plasma was studied in this paper. Flow rate of working gas and protecting gas was changed and the depositing temperature field was measured. Structural homogeneity of deposited silica glass was discussed by optical homogeneity, fictive temperature and stress birefringence. Results show that more uniform temperature field can be obtained with higher working gas flow and lower protecting gas flow, and the structural homogeneity of type IV silica glass is better. But the proportion of working gas and protecting gas should not be larger than 2. When the working gas and protecting gas are 5 m3/h and 2.5 m3/h respectively, the structural homogeneity of type IV silica glass is the best.