A hybrid coil system for high frequency electromagnetic induction sensing

2017 ◽  
Author(s):  
John B. Sigman ◽  
Benjamin E. Barrowes ◽  
Yinlin Wang ◽  
Hollis J. Bennett ◽  
Janet E. Simms ◽  
...  
Keyword(s):  
High Frequency ◽  
Electromagnetic Induction ◽  
Coil System

Coil design considerations for a high-frequency electromagnetic induction sensing instrument

2016 ◽  
Author(s):  
John B. Sigman ◽  
Benjamin E. Barrowes ◽  
Yinlin Wang ◽  
Hollis J. Bennett ◽  
Janet E. Simms ◽  
...  
Keyword(s):  
High Frequency ◽  
Electromagnetic Induction ◽  
Coil Design ◽  
Design Considerations

scholarly journals High-Frequency Electromagnetic Induction (HFEMI) Sensor Results from IED Constituent Parts

2019 ◽  
Vol 11 (20) ◽  
pp. 2355 ◽  
Author(s):  
Benjamin Barrowes ◽  
Mikheil Prishvin ◽  
Guy Jutras ◽  
Fridon Shubitidze
Keyword(s):  
High Frequency ◽  
Electromagnetic Induction ◽  
Low Frequency ◽  
Test Site ◽  
Frequency Range ◽  
Discrimination Capability ◽  
Metal Detectors ◽  
Metallic Parts ◽  
Ground Penetrating ◽  
Improvised Explosive

The detection and classification of subsurface improvised explosive devices (IEDs) remains one of the most pressing military and civilian problems worldwide. These IEDs are often intentionally made with either very small metallic parts or less-conducting parts in order to evade low-frequency electromagnetic induction (EMI) sensors, or metal detectors, which operate at frequencies of 50 kHz or less. Recently, high-frequency electromagnetic induction (HFEMI), which extends the established EMI frequency range above 50 kHz to 20 MHz and bridges the gap between EMI and ground-penetrating radar frequencies, has shown promising results related to detecting and identifying IEDs. In this higher frequency range, less-conductive targets display signature inphase and quadrature responses similar to higher conducting targets in the LFEMI range. IED constituent parts, such as carbon rods, small pressure plates, conductivity voids, low metal content mines, and short wires respond to HFEMI but not to traditional low-frequency EMI (LFEMI). Results from recent testing over mock-ups of less-conductive IEDs or their components show distinctive HFEMI responses, suggesting that this new sensing realm could augment the detection and discrimination capability of established EMI technology. In this paper, we present results of using the HFEMI sensor over IED-like targets at the Fort AP Hill test site. We show that results agree with numerical modeling thus providing motives to incorporate sensing at these frequencies into traditional EMI and/or GPR-based sensors.

High-Frequency Electromagnetic Induction Sensing of Nonmetallic Materials

2017 ◽  
Vol 55 (9) ◽  
pp. 5254-5263 ◽  
Author(s):  
John Brevard Sigman ◽  
Benjamin E. Barrowes ◽  
Kevin O'Neill ◽  
Yinlin Wang ◽  
Janet E. Simms ◽  
...  
Keyword(s):  
High Frequency ◽  
Electromagnetic Induction

scholarly journals Contactless Ultrasonic Cavitation in Alloy Melts

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3610 ◽  
Author(s):  
Koulis Pericleous ◽  
Valdis Bojarevics ◽  
Georgi Djambazov ◽  
Agnieszka Dybalska ◽  
William D. Griffiths ◽  
...  
Keyword(s):  
High Frequency ◽  
Electromagnetic Induction ◽  
Acoustic Resonance ◽  
Grain Refiner ◽  
Melt Treatment ◽  
Treatment Volume ◽  
Added Benefit ◽  
Flow Heat ◽  
Higher Temperature ◽  
Software Coupling

A high frequency tuned electromagnetic induction coil is used to induce ultrasonic pressure waves leading to cavitation in alloy melts. This presents an alternative ‘contactless’ approach to conventional immersed probe techniques. The method can potentially offer the same benefits of traditional ultrasonic treatment (UST) such as degassing, microstructure refinement and dispersion of particles, but avoids melt contamination due to probe erosion prevalent in immersed sonotrodes, and it can be used on higher temperature and reactive alloys. An added benefit is that the induction stirring produced by the coil, enables a larger melt treatment volume. Model simulations of the process are conducted using purpose-built software, coupling flow, heat transfer, sound and electromagnetic fields. Modelling results are compared against experiments carried out in a prototype installation. Results indicate strong melt stirring and evidence of cavitation accompanying acoustic resonance. Up to 63% of grain refinement was obtained in commercial purity (CP-Al) aluminium and a further 46% in CP-Al with added Al–5Ti–1B grain refiner.

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