  Plasma properties inside a hydrogen-filled capillary discharge waveguide were
modeled with dissipative magnetohydrodynamic simulations to enable analysis of
capillaries of circular and square cross-sections implying that square
capillaries can be used to guide circularly-symmetric laser beams. When the
quasistationary stage of the discharge is reached, the plasma and temperature
in the vicinity of the capillary axis has almost the same profile for both the
circular and square capillaries. The effect of cross-section on the electron
beam focusing properties were studied using the simulation-derived magnetic
field map. Particle tracking simulations showed only slight effects on the
electron beam symmetry in the horizontal and diagonal directions for square
capillary.
