Abstract: An optically pumped, flowing gas, alkali metal laser includes a gas passageway transporting an alkali metal vapor and a hydrocarbon buffer gas, and a laser propagation passageway intersects the gas passageway and forms a main cell at the intersection. A pump laser is directed into the main cell and produces a main laser beam in the laser propagation passageway. The flowing hydrocarbon buffer gas is disposed in the main cell with a density to induce spin-orbit relaxation in the alkali metal vapor. At least one window is disposed in the laser propagation passageway, and the window is protected from deposits of alkali metal or carbon by a heated leading edge in the laser propagation passageway that re-vaporizes alkali metal and returns it to the gas passageway via a convective gas flow. The window is further protected by a cold block that liquefies alkali metal and by a colder block that solidifies alkali metal in the laser propagation passageway.