Cylindrical-shaped graphite field emitters with total emission areas of about 100 and 800 cm(2) Were used to construct an x-ray source in which the anode consists of a 107 cm long quartz tube, 7.7 cm outer diameter, and a wall thickness of 0.4 cm. Except for the end portions, the tube is coated with a 5 mu m Cu film. The emitter surface is 0.35 cm separated from the quartz tube. Electrons originating from the emitter surface impinge upon the copper film and some of them are converted into x rays. The x rays penetrating the quartz tube can be utilized for irradiation experiments where ionizing radiation is desirable. X-ray spectra, photon count rate, and dose rate were measured, as well as current-voltage characteristics of the two field emitter configurations. Within the "hot" zone of the. 5 and 30.5 cm long emitter regions, the dose is uniform within +/- 20% in the lateral direction and +/- 20% along the inner surface of the quartz tube. (The "hot" zone is defined as the region where the x rays are generated). It was established that the photon count and the dose scale proportional with the emission current and increase exponentially with target voltage. The x-ray source was operated to 42.5 kV at a pressure of 5 x 10(-7) Torr. (c) 2005 American Vacuum Society.