An apparatus capable of producing current or voltage controlled positive and negative ion beams in 1‐atm oxidizing and nonoxidizing ambients between 25° and 950 °C is presented. The apparatus utilizes a point‐to‐plane corona discharge in the gas phase. Room‐temperature experiments revealed that the small differences in ion beam shape between the two polarities is primarily due to the difference in applied voltage required to produce the same current for the two polarities. Due to increased ion mobility and decreased threshold voltage at higher temperatures, a slight broadening of the ion beam current‐density profiles for both positive and negative ions is predicted.