A system for circulating an alkali vapor to operate as, for example, a gain medium in a diode pumped alkali laser. The system includes a pump configured to pump a buffer gas to a metal source. A source heat exchanger heats the alkali metal source to produce a metal vapor that flows with the buffer gas. An action chamber receives the metal vapor and buffer gas combination and contains the combination while the metal vapor performs its required functions. The metal vapor and buffer combination continue to flow to a metal vapor trap and heat exchanger that cools the metal vapor and buffer gas combination. The metal vapor trap collects alkali metal condensate as the combination cools. The diffuser transport channel provides an inflow of clean buffer gas to the pump. The pump provides a circulating gas flow through the closed loop system.