Pinhole detection in thin foils used in space plasma diagnostic instrumentation

The efficiency of thin foils which are used for charge state modification, start/stop pulse triggering, and UV shielding in space plasma diagnostic instrumentation is highly sensitive to pinholes in the foil. In this study, we present a high resolution method to map pinhole locations and sizes in thin foils based on the different transmission properties of incident ions through holes and hole-free regions of the foil. Results are presented for 200-eV ions transmitted through 0.2-, 0.5-, and 1.0-μg/cm2 carbon foils. Acceleration of transmitted ions into the imaging detector increases both the imaging resolution and the contrast between holes and hole-free regions of the foil.