2013 International Conference on Lightning and Static Electricity (ICOLSE), September 18-20, 2013
NASA Langley Research Center (LaRC) is conducting research to develop an open circuit SansEC (Sans Electric Connection) sensor to provide lightning strike protection (LSP) in conjunction with damage detection and diagnosis for composite aircraft. SansEC sensors are simplistic devices consisting of an open circuit conductive trace shaped in a planar geometric spiral. The length and width of the conductive trace as well as the gap separation between adjacent turns determines the inductance, resistance and capacitance of the LRC circuit and its associated resonant response. When the sensor is placed on a composite substrate, the electric impedance of the substrate is reflected in the sensors resonant response thus enabling it to detect permittivity and conductivity changes associated with composite damage. SansEC sensors can be designed in various shapes and sizes depending on the application. For applications on exterior aircraft surfaces, the sensor must be designed to perform the required lightning strike protection in addition to damage detection and diagnosis.  
Lightning-direct effect current tests were conducted on multiple SansEC sensor configurations to evaluate their ability to withstand the incident lightning energy and protect the underlying composite. Test results indicated several SansEC sensor geometric configurations demonstrated an intrinsic ability to steer the lightning current along the corner of the sensor. To investigate this phenomenology, electromagnetic computational simulations were conducted to calculate the electric field distribution on the SansEC sensor’s conductive trace to determine if the associated electromagnetic radiation preceding lightning attachment establishes modal structures on the conductive trace which predisposition the direction of the current flow. The simulations provide a means to visualize the trace’s modal structure and identify electric field regions residing on the sensor. This paper presents a correlational study of the SansEC sensor’s computed electric field distribution to the measured lightning propagation direction for various SansEC sensor configurations. The study suggests the direction of lightning propagation follows strong electric field regions resident on the conductive trace.
Original Publication Citation
Farrow, K. M., & Vahala, L. L. (2013). Correlational Study of Open Circuit Resonant (SansEC) Sensor’s Electric Field Distribution on Lightning Attachment. Paper presented at the 2013 International Conference on Lightning and Static Electricity (ICOLSE).
Farrow, Kayla M. and Vahala, Linda L., "Correlational Study of Open Circuit Resonant (SansEC) Sensor’s Electric Field Distribution on Lightning Attachment" (2013). Electrical & Computer Engineering Faculty Publications. 127.