A 6 cm diameter, 6 cm long multicusp ion source was used to test the extraction characteristics of both the surface‐produced and volume‐produced Li−ion beams. The ion source was equipped with a Li oven, a Cs oven, and a heat shield to increase the recirculation of alkali metals. A preliminary test with a low arc power discharge showed that the amount of Li−current extracted from a Li plasma can be doubled by the addition of Cs into the discharge. Merits and demerits of using a volume production Li−source for plasma diagnostic applications are discussed by comparing the performance with that of a surface conversion Li−source.