Micromachined Ion Shutters

Micromachined shntters of comparable dimensions and structures were described in detail and used in a time-of-flight mass spectrometer (MS). The wires or electrodes were spaced at distances ranging from 25 to 100 pm and with a thickness of 20 pm. Other parameters for this shatter were 400 pm total thickness 20-pm electrode depth 100-pm electrode pitch 128-pF capacitance 80% transmission and 25 mm total area of the grid with a 5 by 5 mm shape. The transmission efficiency was comparable to wire shutters, and performance was good, with rise and fall times of 0.2 ps. 

FIGURE 5.3 Grid for ion shutter. Two grids of this design have been employed on drift tubes built for 3QB in Israel. (Courtesy Z. Karpas.) 

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