The helical instability of an arc column with electrical conductivity of the parabolic distribution and macro velocity is discussed in an axial magnetic field. The magnetohydrodynamic equations serve as the starting point of the theory, in an electrostatic approximation and a linear time dependent perturbation theory, the perturbation equations for the arc column movement are deduced. Solutions of these equations are obtained analytically, from which the stability limit of the cylindrical arc and the growth rate of the helical instability are given.

The Boltzmann transport equation and the new results obtained in the interaction between the particle and solid materials research are applied to calculate the ion range in targets. The results calculated are compared favorably with experimental results and the results calculated by the famous Monte carlo code TRIM.

Electron energy distributions of direct-curent argon discharges at low pressures were calculated by numerically solving the homogeneous Baltzmann equation. The calculations cover the whole range of low electron densities to sufficiently high electron densities. Typical values of the ratios of the electric field to the gas density in this work are in the renges of 10^-16 < E/N < 10^-15 Vcm². The influence of electron-electron collisions and the electric field on the electron energy distribution function was studied.

The stopping powers and energy stragglings for implanted ions in strongly coupled degenerate electron gas were investigated using local-field correction dielectric function.The numerical results have shown thst the stopping powers and energy stragglings were considerably increased due to local-field correction at low volecities and high valuse r_s.