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Advanced Optics Based Magnetic Field Diagnostic for NWE Testing


RT&L FOCUS AREA(S): 5G, General Warfighting Requirements (GWR); Nuclear TECHNOLOGY AREA(S): Nuclear; Sensors; Electronics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: The objective of this effort is to develop an advanced optics based magnetic field sensor for Nuclear Weapon Effects (NWE) testing. The sensor should be low-cost and able to operate with high accuracy in a wide range of X-ray and gamma environments. DESCRIPTION: Military system components are tested in X-ray and gamma radiation simulators, for time-varying Nuclear Weapon Effects (NWE), such as System Generated Electromagnetic Pulse (SGEMP), Internal EMP (IEMP), and Open Cavity SGEMP. These effects are caused by electrons emission from conducting surfaces which generate surface currents (with associated electric and magnetic fields). These magnetic fields can have strengths of order 1 to 1000 Amps/meter with rise times of order of nanoseconds (ns). It is important to measure the magnetic fields produced by pulsed X-ray exposures to validate models of a system’s response. Traditionally, the magnetic fields of these NWE effects are measured with small B-Dot probes (simple induction coils), placed close to the external or internal surfaces of the test object. These sensors face challenges related to their miniaturization, Electromagnetic Interference (EMI) susceptibility and fielding considerations within a test object [1, 2]. Optical fiber based magnetic field sensors, offer several advantages which includes having a smaller size, reduced susceptibility to EMI noise and increased dynamic range [1]. These sensors are seldom fielded for NWE testing due to the requirement to be high speed, minimally intrusive and able to operate in a harsh environment [3]. The objective of this effort is to develop an advanced optics based magnetic field sensor appropriate for NWE testing. DTRA seeks innovative ideas for the development of an advanced optics based magnetic field sensor suitable for NWE testing. The proposed magnetic field sensor should include the sensor probe as well as the measurement and recording instrumentation capable of nanosecond time resolution. The system must maintain the integrity of the magnetic field information sensed at the probe and transmitted to the recording instrumentation. The sensor probe should be low-cost, easily replaceable, small and able to operate with high accuracy in a wide range of X-ray and gamma environments. Phase 1 development should result in a conceptual design of the proposed sensor and demonstrates its feasibility for NWE related testing. Phase II development will further optimize the design of the sensor, fabricate and demonstrate that the design meets or exceeds the following threshold {objectives}: 1. B-Field Measurement Range: 0.01 to >1000 A/m 2. Accuracy: better than 5% 3. Bandwidth: >100 MHz 4. Rise Time: <3.5 ns 5. Be low cost and have a replaceable sensing element. 6. Be compact: the sensing element to be no larger than 1cm3. PHASE I: Investigation will develop a conceptual design of the optics based magnetic field sensor that, at a minimum, addresses the stated objectives presented in the Description. Demonstrate the feasibility of the sensor design with performance predictions based on peer-reviewed literature, physics-based modeling and simulation, and/or data obtained from laboratory testing of sensor components. Develop a Phase development II plan. PHASE II: Based on the results of Phase I, develop and deliver a prototype that demonstrates the performance of the chosen technology for this application and meets all stated minimum requirements stated in the Phase II development plan and objectives stated in the Description. Collaborate with Government personnel to test the prototype over its full dynamic range to ensure the capability meets the performance goals. PHASE III DUAL USE APPLICATIONS: Optimize sensor design and demonstrate performance in an operational environment. Develop manufacturing and commercialization plans for implementing the research in production and dissemination of the sensors, respectively. This technology would benefit any organization seeking a low cost, small, robust magnetic field sensor. REFERENCES: 1. Alberto, Neilia et al. “Optical Fiber Magnetic Field Sensors Based on Magnetic Fluid: A Review”, Sensors (Basel, Switzerland) Vol 18, 12 4325. 7 Dec 20182. 2. K.B. Fournier et al. “Conducting Open-Mouth-Cavity SGEMP Experiments at the Helen Laser Facility”, JRE, Vol 27, Num 1, pg 51-71, July 20103. 3. R.D. McBride et al. “Implementing and Diagnosing Magnetic Flux Compression on the Z Pulsed Power Accelerator”, SAND2015-9860, 9 November 2015
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