Abstract: A hand-held probe assembly has two fixed probe legs and two movable probe legs disposed in a linear array. A pair of probe legs, one of which is fixed and one of which is movable, is engageable with a first plate edge portion. A second pair of fixed and movable probe legs is engageable with a second plate edge portion. Retractable alignment legs engage a joint between the plate edge portions to aid in positioning the probe assembly relative to the plate edge portions. In an alternative embodiment of the invention, an alignment leg engages opposite sides of a joint between the plate edge portions to hold the probe assembly centered relative to the joint. The probe assembly generates electrical signals corresponding to the extent of movement of the movable probe legs. Using these electrical signals, a microcomputer calculates the peak angle and the mismatch at the joint between the plate edge portions.

Abstract: Electrostatic cooling apparatus with a needle emitter insulated along the shank thereof except for a sharp needle tip. The insulated needle emitter is supported along the axis of a funnel tube so as to augment the velocity of the ionic wind generated by the needle emitter. The needle emitter is axially adjusted within the funnel tube to tune the resonant cavity formed by the needle emitter and funnel tube to just below the space charge oscillation frequency.