An electric excitation signal having a frequency " f " will therefore resonate with ions having a mass-to-charge ratio " m / z " given by
2.
Subsequently, in the 90s, CRGs with magneto-electric excitation and readout were produced by American based Inertial Engineering, Inc . in California, and piezo-ceramic variants by Watson Industries.
3.
Between 1945 and 1960, the French researcher No�l Felici developed a series of high-power electrostatic generators, based on electric excitation and using cylinders rotating at high speed and hydrogen in pressurized containers.