Time‐of‐flight spectrometer for an ECR ion source

A time‐of‐flight ion spectrometer using electrostatic grids for ion gating is described. The spectrometer was built to monitor the charge state distribution of endloss ions passing from the midplane region of an ECR‐heated, simple magnetic‐mirror plasma experiment. Design considerations of the spectrometer are presented as well as the gating pulse circuit and signal amplifier circuit. An example of a time‐averaged spectrum is included to illustrate the achievable resolution of the spectrometer. Also a method is described to determine the ion energy distribution of a given charge state in the ion endloss.