Measurements of space potential by the time of flight of heavy ions

A technique has been developed to measure potential variations produced by space charge. The method consists in directing a beam of fast heavy ions through the region of interest and measuring the time of flight. The flight time is measured by intensity-modulating the beam and detecting the resulting phase shift between the collector and the ion source. Results of experiments performed using a simulator show that a direct reading of potential change of a few volts can be obtained with a temporal resolution of about 10 μs. (author)