Spoof Plasmon Sensing for NDE Applications

NASA is exploring the use of microwave spoof plasmon polaritons to detect defects in metallic structures. This work investigates the detection of simulated defects in the form of aluminum wires as small as 1.6 mm diameter and 2 mm long that are placed in a grooved aluminum test article. The inclusions simulate manufacturing defects, and the sum of the delta impedance is shown to increase with increasing volume of added metal. Based on the results, a threshold value of
$50\Omega$
has been proposed for defect detection. In addition to detecting defects, the technique also estimates the volume of the defect.