Abstract: A thermal structure and cooling system for an argon-ion laser that is virtually free of thermal asymmetries includes a laser cathode having a housing constructed of a material of high thermal conductivity and relatively low thermal expansion in conjunction with a cooling structure configuration which readily and uniformly dissipates heat. In a specific embodiment the support structure is fabricated of copper material of at least a minimal thickness and the cooling fins are disposed in one and two stages of radial fins at specified regions along the support structure forming the discharge tube and enclosed by a tubular thermally conductive band.