An apparatus for purifying a controlled-pressure environment in a chamber, including: a piece of lithium-aluminum alloy located in the chamber; an activation element arranged to impart energy to the piece of lithium-aluminum alloy to sublimate lithium from the piece of lithium-aluminum alloy; a feedback control system including a sensor system arranged to measure a condition within the chamber, and a controller in communication with the sensor and configured to control operation of the activation element according to an evaluation of the condition; and a collection plate located in the chamber and arranged to form a layer of the sublimated lithium on a surface of the collection plate.