A hot cathode ion source has been developed to produce pulsed ion beams. The source has a canal electrode whose characteristics resemble those of the grid of a vacuum triode. The characteristics are attributed to sheath formation in the canal. The ratio of the maximum current to the minimum is about 103. A pulsed ion beam of a milliampere of submicrosecond duration has been easily obtained with a low power pulser. The rise time of the pulsed current is 0.1 &mgr;sec.