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An Intrinsic Fiber-Optic Sensor for Structure Lightning Current Measurement
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Author and Affiliation:
Nguyen, Truong X.(NASA Langley Research Center, Hampton, VA, United States);
Ely, Jay J.(NASA Langley Research Center, Hampton, VA, United States);
Szatkowski, George N.(NASA Langley Research Center, Hampton, VA, United States);
Mata, Carlos T.(NASA Kennedy Space Center, Cocoa Beach, FL, United States);
Mata, Angel. G.(Stinger Ghaffarian Technologies, Inc. (SGT, Inc.), Kennedy Space Center, FL, United States);
Snyder, Gary P.(NASA Kennedy Space Center, Cocoa Beach, FL, United States)
Abstract: An intrinsic optical-fiber sensor based on Faraday Effect is developed that is highly suitable for measuring lightning current on aircraft, towers and complex structures. Originally developed specifically for aircraft installations, it is light-weight, non-conducting, structure conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can measure total current down to DC. When used on lightning towers, the sensor can help validate other sensors and lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. A broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with a 60 dB dynamic range. Two systems were built that are similar in design but with slightly different sensitivities. The 1310nm laser system can measure 300 A - 300 kA, and has a 15m long sensing fiber. It was used in laboratory testing, including measuring current on an aluminum structure simulating an aircraft fuselage or a lightning tower. High current capabilities were demonstrated up to 200 kA at a lightning test facility. The 1550nm laser system can measure 400 A - 400 kA and has a 25m fiber length. Used in field measurements, excellent results were achieved in the summer of 2012 measuring rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida. In both systems increased sensitivity can be achieved with multiple fiber loops. The fiber optic sensor provides many unique capabilities not currently possible with traditional sensors. It represents an important new tool for lightning current measurement where low weight, complex shapes, large structure dimension, large current, and low frequency capabilities are important considerations.
Publication Date: Mar 18, 2014
Document ID:
20140003896
(Acquired May 02, 2014)
Subject Category: AIR TRANSPORTATION AND SAFETY
Report/Patent Number: NF1676L-17508
Document Type: Conference Paper
Meeting Information: International Lightning Detection Conference (ILDC); 23rd; 18-19 Mar. 2014; Tucson, AZ; United States
International Lightning Metrology Conference (ILMC); 5th; 20-21 Mar. 2014; Tucson, AZ; United States
Contract/Grant/Task Num: WBS 648987.02.04.07.20
Financial Sponsor: NASA Langley Research Center; Hampton, VA, United States
Description: 12p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: ALTERNATING CURRENT; DYNAMIC RANGE; FARADAY EFFECT; FIBER OPTICS; LASERS; LIGHTNING; LOW FREQUENCIES; LOW WEIGHT; MAGNETIC FIELD CONFIGURATIONS; POLARIMETRY; POLARIZATION (WAVES)
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