TECHNOLOGY AREAS: Sensors, Electronics, Weapons

ACQUISITION PROGRAM: Office of Naval Research Code 352: Railgun Innovative Naval Prototype (INP)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop diagnostic techniques for measuring field quantities in a railgun during launch.

DESCRIPTION: The US Navy is pursuing the development of an electromagnetic launcher (also known as a railgun) for long range naval surface fire support. An electromagnetic launcher consists of two parallel electrical conductors, called rails, and a moving element, called the armature. Current is passed down one rail, through the armature, and back through the other rail. The armature is accelerated down the barrel due to the interaction between this magnetic field and current flow (Lorentz Force).

The extreme electromagnetic field, current, temperatures and stresses in the rails and armature create a harsh environment within the launcher. This severe environment makes direct measurements of these field quantities during firing difficult with conventional diagnostics. It is desirable that the instrumentation survive repeated exposure to this environment to allow for health monitoring.

In order to create M&S tools to aid in design and predict performance, several different field quantities need to me measured. This effort would develop diagnostics to measure one or more quantities such as temperature, strain, magnetic field, electric field, and current density in the armature and rails. Other measurements of interest are spectroscopy and multi-axis acceleration of the armature. Fields within the rails evolve over timescales of approximately 10 microseconds, and so a frequency response of at least 1MHz is desired. Fields within the armature evolve over a much longer timescale, approximately 1 millisecond, and so a frequency response of 10 kHz for armature diagnostics may be adequate. While small access holes in the rails and armatures may be allowable, it is not desired.

Two classes of diagnostics are envisioned. First, diagnostics suitable for laboratory use and second, diagnostics that can be used as a health monitoring tool. It is hoped that this will allow a tradeoff between performance and robustness. The awardee is encouraged to explore innovative transducer technologies that are insensitive to EMI especially, but are also immune to high temperatures, strains, and temperature and strain rates.

PHASE I: Investigate transducer technologies that will provide one, some, or all the necessary data to characterize the behavior of the launcher. Conduct bench-top tests of promising technologies that demonstrate the proposed transducer(s) will survive static magnetic fields of 10 Tesla and temperatures of 300 deg. C. The outcome should be two transducers that show promise for further study.

PHASE II: Design and fabricate prototype transducers, signal cable, and data acquisition and test in a transient environment similar to the railgun. Magnetic fields should be 30 Tesla and temperatures of 300 deg. C. The outcome should be at least one transducer that show promise for testing in a railgun. Also in phase II, a design study should be performed to show the robustness of the concept against all environments expected in the railgun, particularly strain and strain rate. Perform a trade study to show the tradeoff between a diagnostics system suitable for laboratory use vs. one suitable for shipboard installation for health monitoring.

PHASE III: Incorporate the instrumentation into an existing launcher. Perform measurements in an EM gun during firing. The EM gun may be available as a gov�t furnished test asset or as a teaming relationship with other EM gun test sites. Potential test sites include various scale railguns operated by Universities and Defense contractors. If successful, work with Navy contractors to incorporate the instrumentation into advanced launcher concepts being developed by industry. If necessary, modify design to allow for use in an at-sea environment to enable transition to PEO IWS, PMS 405, ONR Program Office and integration with industry launcher manufacturers' production weapon systems that will be sent to the fleet.

The results of testing may be classified. The Phase III product may become classified.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The measurement techniques that are developed could have application for large scale, high power electric motors for electric ships or UAV�s, switch diagnostics, and high current electric transportation (cars, trains, etc.). The measurement techniques developed may also be used in the automotive and aviation industry for safety monitoring and non-destructive evaluation as well as for any structural diagnostic requiring high frequency response such as magneforming operations.

REFERENCES:
1. Allison, S.W.; Cates, M.R.; Goedeke, S.M.; Akerman, A.; Crawford, M.T.; Ferraro, S.B. Stewart, J.; Surls, D., "In-Flight Armature Diagnostics", Magnetics, IEEE Transactions on, Volume: MAG-43 Issue: 1, January 2007, Page(s): 329-333.

2. Knoth, E.A.; Challita, A., "A Diagnostic Technique for Understanding Startup of Metal Armatures", Magnetics, IEEE Transactions on, Volume: MAG-33 Issue: 1, January 1997, Page(s): 115-118.

3. Derbidge, T.C.; Micali, J.V., "A Gage for Measuring Heat Transfer to the bore of electromagnetic Railguns", Magnetics, IEEE Transactions on, Volume: MAG-27 Issue: 1, January 1991, Page(s): 202-206.

4. Zelinsky, A.E.; Le, C.D.; Bennett, J.A., "In-bore Electric and Magnetic Field Environment", Magnetics, IEEE Transactions on, Volume: MAG-35 Issue: 1, January 1999, Page(s): 457-462.

KEYWORDS: Electromagnetic launcher; railgun; measurement; diagnostic; stress; temperature

TPOC: Benjamin McGlasson
Phone: (540)653-1647
Fax: (540)653-5304
Email: [email protected]
2nd TPOC: Roger Ellis
Phone: (703)696-9504
Fax: (703)696-4274
Email: [email protected]
3rd TPOC: Moises Iglesias
Phone: (540)653-1260
Fax: (540)-284-0413
Email: [email protected]

** TOPIC AUTHOR (TPOC) **

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