BEAM VOLTAGE MANIPULATION FOR TIME-OF-FLIGHT MASS ANALYSIS OF CONTINUOUS ION-BEAMS

Beam voltage manipulation has been used for time-of-flight mass analysis of a continuous ion beam without separation of pulses from the continuous beam. The procedure defines a pulse of ions in the continuous beam by tagging the pulse with a slightly different beam energy. This is accomplished, in a remarkably simple fashion, by directing the ion beam through a short tube to which a 10-V square wave is applied. Ions that have had their beam energy manipulated leave a hole at the time they would have arrived and accumulate at their new arrival time. These changes in the ion current are readily detected when observed on the time scale of ion flight through the beam line. It is hoped that this particular application indicates a general utility for beam voltage manipulation-specifically the ability to modulate a continuous ion beam with great control over the wave form of the ion beam's resulting intensity. This attribute should prove useful in a variety of ion optical applications.