TECHNOLOGY AREAS: Materials/Processes, Sensors, Weapons

ACQUISITION PROGRAM: ONR FEL Program and NAVSEA PMS 405

OBJECTIVE: The FEL generates intense photon beams by extracting kinetic energy from very well defined and energetic electron beams. The process requires the production of modest energy (<10 MeV), bright [low emittance - 10 micron] electron pulses. Unlike the entire FEL laser system, the injector and its auxiliary equipment are relatively compact and can be installed in most manufacturing facilities.

The primary objective of this solicitation is to determine if the electron beam characteristics of the FEL injector can be used to good advantage in such applications as e-beam lithography, atmospheric welding, and others. The applications sought must be compelling, have significant utility, be affordable, and provide a unique Navy and/or commercial capability.

DESCRIPTION: Many material processing applications require the controlled input of thennal energy to achieve the desired properties. While the processing of large bulk materials can be adequately achieved with thermally controlled furnaces, some products would greatly benefit by applying varying amounts of heat to local areas to produce unique spatial characteristics. The use of high energy (<10 MeV) electron beams ability to locally deliver thennal energy for material processing opens up some potentially interesting opportunities for both manufacturing military hardware and commercial products.

The interaction of electrons with most manufacturing materials is fundamentally different than that occurring with photon beams. Photon beams tend to deposit most of their energy on the front surface (only a few microns in metals and opaque solids) causing ablation even for relative low power laser beams. This limits the useful amount of energy that can be deposited into materials thus restricting the rate of heating that can be reasonably used for bulk processing. Electron beams deposit their energy in depth; for example a 10 MeV electron can penetrate about one centimeter of aluminum. Since the electrons deliver their energy in to a larger volume of material, faster processing rates can be achieved. Furthermore, the more energetic FEL injector beams do not require the work piece to be maintained in a vacuum as do conventional electron beam welders. An important feature of the FEL injector is that it is deigned to produce high quality beams, which means the electrons can be focused to a relatively small spot size, thereby producing a small heat affected zone.

The FEL uses an electron gun/injector to produce megawatt-class, high-brightness beams that can span a large operational (voltage x current) parameter space. The beam energy can be set to control the electron depth of penetration while the current pulse amplitude and length control the delivered energy. At the electron energies of interest, the e-beam can propagate through controlled atmospheres. This eliminates the need for vacuum chambers used by conventional e-beam welders.

The development of non-weapon gun/injector technologies will require improving the human machine interface for operational and maintenance considerations. Improvements in this area will greatly benefit the FEL INP weapons program much as fiber laser based weapons studies have profited from the advancement of fiber welders.

The purpose of this solicitation is to identify compelling materials processing applications using the FEL INP gun/injector system. From those applications, quantify the beam requirements and describe improvements that e-beam processing provides over conventional heat treatments.

PHASE I: In Phase I, the respondent to this solicitation should identify applications of high power electron beams that will provide a unique and compelling military and/or industrial capability. For each application identified, the respondent shall quantify the required electron beam characteristics such as electron energy, beam brightness, peak power, average power, etc. In addition to the advantages of the e-beam as a quality heat source a listing of the technical challenges such as estimating the amount of ionizing radiation shielding required, a description of methodes) for steering/focusing the beam, a conceptual description of the vacuum interface. In the Phase I report, the respondent should identify first generation applications that can be demonstrated with existing FEL injectors. The study should also provide first order estimates of capital and operating costs for each application, and suggest injector design improvements for making the equipment more user friendly.

PHASE II: The respondent shall perform demonstrations, consistent with available budget to demonstrate the advantages of a high power electron beams identified in Phase 1.
Phase I operating cost estimates shall be revised using results of Phase II. The Phase II study shall include a quality and quantity comparison of e-beam processed materials with those treated with current methods, and estimates of facility production rates.

PHASE III: The respondents shall survey market the e-beam system which shall concentrate on the most compelling applications for military (ship, aircraft and submarine construction; weapons development), and commercial uses. A detailed conceptual engineering facility design(s) for the most promising application(s) should be presented in Phase III report. Special emphasis shall be given to human factors engineering for operations, safety and maintenance.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Several industrial applications could benefit from a successful demonstration of the use of electron beams as a quality focused heat source. Potential examples would be near net shape lithography oflarge components, uniform thermal gradation of turbo-fan blades, pre-stressing of ceramic bearings, food preservation using non-radioactive sources, curing thermo-set plastics, and controlled atmospheric e-beam welding.

REFERENCES:
1. W. A. Barletta, et. al.; "Free Electron Lasers: Present Status and Future Challenges"; Nuclear Instruments and Methods in Physics Research A.; 28 February 2010.

2. "Advanced Materials by Design;" Office of Teclmology Assessment Report, Library of Congress Catalog Card No. 87-619860, Dec 1988 and Materials Science and engineering for the 1990s; Maintaining Competitiveness in the Age of Materials ; National Academy Press ISBN 0-309-03928-2, Washington D.C., 1989;the problems of large rocket booster case welding are descIibed in "The Space Shuttle Advanced Solid Rocket Motor ," National Research Council Report, National Academy Press, Washington, DC, 1991.

3. R. B. Miller; An Introduction to the Physics oflntense Charged Particle Beams, Plenum Press, New York, 1982.

4. W.B. Colson, et al; Proceedings of the 2009 Accelerator Conference, Liverpool, UK, 2009.

KEYWORDS: Free Electron Laser (FEL); Injector; E-Beam; Materials Processing; Manufacturing; Intense Electron Beams (lEB)

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 10 and December 12, 2010, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 13, 2011, when DoD begins accepting proposals for this solicitation.

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