2003-2004 Assessment of the Army Research Laboratory (2005)

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4 Sensors and Electron Devices Directorate INTRODUCTION The Sensors and Electron Devices Directorate (SEDD) was reviewed by the Panel on Sensors and Electron Devices. SEDD has four divisions that are reviewed by the Panel: Electro-Optics and Photonics, Radio Frequency and Electronics, Signal and Image Processing, and Directed Energy and Power Gen- eration. SEDD also has responsibility for the Advanced Sensors Collaborative Technology Alliance (CTA) and the Power and Energy CTA, and it contributes to the Robotics CTA managed by ARL’s Weapons and Materials Research Directorate (WMRD). Each CTA began in 2001 and has a 5-year term, with an option for 3 more years. Tables A.1 and A.2 in Appendix A respectively characterize the funding profile and the staffing profile for SEDD. CHANGES SINCE THE PREVIOUS REVIEW SEDD continues to do an excellent job of maintaining and building its capabilities. During the period from FY 2000 through FY 2003, 92 new staff members were hired, as opposed to the loss of 79, and the percentage of staff with Ph.D.s has steadily increased. The SEDD staff remains enthusiastic about their research, technically competent, and highly qualified. In past years, the Future Combat Systems (FCS) program provided a focal point for much of SEDD’s research, but in the 2004 presentations, FCS was barely mentioned in the SEDD overview. In past years, FCS capability goals frequently provided starting points for the flow from military needs, to technical problem definition, to motivation for specific research; but many of this year’s technical presentations lacked discussion of this essential flow. This change is probably at least partially due to 21 

22 2003–2004 ASSESSMENT OF THE ARMY RESEARCH LABORATORY the Army’s current focus on Afghanistan and Iraq and to uncertainties with respect to FCS procurement methods and emphasis. The Army’s decision to give the FCS’s system integration contractor (Boeing) an unprecedented level of influence on the definition and development of major combat systems has the potential for great impact on SEDD. In the past, the Training and Doctrine Command (TRADOC) was the major source of requirements for new capabilities, and the Research, Development, and Engineering Centers (RDECs) were the major insertion points for SEDD science and technology. The apparent latitude in Boeing’s FCS contract seems to have potential for disrupting traditional ways of establishing require- ments and making technology development and insertion decisions. If this proves to be the case, it will have major impact on SEDD’s fundamental business relationships with contractors and other govern- ment organizations. ACCOMPLISHMENTS AND OPPORTUNITIES Most Significant Advances SEDD has identified some of the Army’s most pressing technology needs and is engaged in a wide array of promising research endeavors focused on these needs and opportunities. For example, SEDD has recognized that improved power generation and management are essential to the reduction of logistics requirements and to realizing a wide array of important new capabilities. SEDD is developing many important new technologies. They include fuel cells, rechargeable batter- ies, matrix power converters, silicon carbide (SiC) power management devices, and high-energy battery technology. Improved sensors are critical to giving lighter forces an essential edge by winning the information battle, and SEDD is deeply engaged in a multitude of efforts focused on sensor develop- ment. As evidenced by the presentation to the Panel on cold atom optics, SEDD is also addressing new developments in basic science that may provide solutions to problems of critical importance, such as underground facility detection and high-accuracy, jamproof navigation. The radio-frequency (RF) group is to be commended for outstanding performance and clearly defined objectives that are aligned with ARL goals. The group is well known in the RF community and is highly regarded for its expertise. SEDD’s work on acoustic detection is especially impressive. The Panel and the Board commend the focus of SEDD on acoustic sniper- and mortar-location systems assembly for field units as an immediate response by SEDD to an urgent Army problem. Opportunities and Challenges SEDD has exceptional strength in a number of areas, including RF radar and communications, acoustic sensing, advanced sensors, and image processing. The current resource level for the program in Power and Energy Systems appears to be inadequate to achieve the goals and roadmaps, but the earmarking of $600 million for the next 5 years for the Army’s Power and Energy program is applauded. Hybrid Electric Propulsion and Power is a promising project, but issues pertaining to energy storage that may be the limiting factors for this technology (battery, flywheel, and supercapacitors) need more consideration. The Board recommends continued examination of the appropriateness of spending 6.1 (basic research) funds on the Power and Energy CTA, which is clearly development-oriented as opposed to being long-range research. This is an impor- 

SENSORS AND ELECTRON DEVICES DIRECTORATE 23 tant issue, since 6.1 funds are generally more difficult to obtain than are 6.2 (applied research) or 6.3 (advanced technology development) funds. In the area of fuel cells, and particularly with regard to fuel reformation, the Panel and the Board note apparent gaps within some of the projects. For example, ARL-funded research at the University of Minnesota produces a gas stream containing hydrocarbons, but none of the downstream processing deals with these hydrocarbons. Good coordination is necessary among the programs developing the components of the fuel reformation system if sufficiently clean hydrogen for the polymer electrolyte membrane fuel cell (PEM FC) is to be produced. There does not appear to be a direct connection between the fuel cell work being performed at SEDD and the work being performed at major automotive companies or at other corporations involved in fuel cell development. SEDD should proactively inves- tigate commercial fuel cell activities and the potential for use of commercially available fuel cells for Army applications. For the High Power Li-Ion Batteries project, more work involving cell cycling under high power conditions at high and low temperature is justified. Now that some interesting electrolyte compositions and some alternative cathode materials are available, the choices should be narrowed on the basis of the performance and life testing of cells from commercial vendors. The general methodology is appropriate, but some important variables affecting the capacity of the air electrode of the lithium (Li)/air cell are not being pursued (i.e., the porosity and pore size distribution are variables that are very likely to yield improved specific capacities). Li-ion batteries should continue to be examined in light of the focus on low-temperature performance. A clear roadmap for Li-ion battery development and deployment would be useful. Considering the Army needs for alternating current (ac)/ac, direct current (dc)/ac, and ac/dc con- verters and switches of different ratings and application constraints, a valuable research project would be to seek a building-block approach that is based on the repetitive use of a limited number of module designs. Work on advanced silicon (Si)-based symmetrical devices should also be undertaken, and research and development on converters should include converters other than matrix converters. With respect to SEDD’s work on electric power systems for FCS and robotic platforms, it is important that SEDD maintain strong connections with the community at large. These connections are important because of the extensive work being done by nonmilitary laboratories such as those of the major auto companies and by agencies such as the Department of Energy (DOE). The Panel and the Board are particularly impressed with SEDD’s extremely important programs focusing on SiC-based converters, such as ac-ac mobile electric power converters and pulse converters for distributed electromagnetic armor. However, the objectives for SiC-based converters are not stretched sufficiently and should be accelerated and expanded to 200 kilowatts (kW) for all SiC-based converters by FY 2005. SEDD needs to make a full assessment of the ongoing developments by industry of SiC diodes to target only needed development areas with ARL research. The work on high-energy lasers for directed-energy weapons is fairly limited compared with that of other services and of agencies such as the DOE. It is recommended that SEDD keep abreast of these other programs and their potential applications and adoption by the Army. Acoustics is especially important to the Army at this time. The scope, high level of activity, and importance of acoustics would suggest that more personnel and a significant long-term investment for this area should be considered. A long-term plan of basic research to advance acoustic sensors (not just signal processing) is needed. It might start with a clear definition of what might be done with better sensitivity, better range, and other performance goals and then continue with a focus on how to get there. Piezoelectric microelectromechanical systems (MEMS) and nanodevice research comprise an area that merits more emphasis and is related to MEMS reliability. While the group is focused on the 

24 2003–2004 ASSESSMENT OF THE ARMY RESEARCH LABORATORY production of working devices with specific performance goals—and robust performance is one of those goals—more specific reliability performance goals should be included, because reliability remains one of the top issues for MEMS. CONTRIBUTIONS TO ARMY NEEDS AND THE BROADER COMMUNITY Contributions to Army Needs SEDD is serving the Army and the United States very well. It is responding to wartime needs in an effective and timely manner, without losing its focus on developing technologies for the Army’s future. An organization that can give good presentations on acoustic sniper- and mortar-location systems that were fielded within 45 days and on something as futuristic as cold atom optics is truly impressive. SEDD is continuing to attract highly qualified scientists and engineers and to develop its infrastructure of facilities and capital equipment. The quality of SEDD research appears to be high in most areas. As mentioned, this directorate has identified some of the Army’s most pressing technology needs and is engaged in a wide array of promising research endeavors focused on these needs and opportuni- ties. This effective focus was suggested by the discussion of SEDD accomplishments above. They include SEDD’s work to improve power generation and management in order to reduce logistics re- quirements and to realize important new capabilities; SEDD’s development of important new technolo- gies, such as fuel cells, rechargeable batteries, matrix power converters, silicon carbide power manage- ment devices, and high-energy battery technology; improved sensors; and contributions to information warfare. Also, as indicated above, SEDD is addressing new developments in basic science that may provide solutions to problems of critical importance, such as underground facility detection and high- accuracy, jamproof navigation. While there may be a few problems with specific details of the research, it is important to recognize that SEDD is deeply engaged and generally making good progress. The acoustic detection work being done by the directorate is impressive, and the focus on the assembly of acoustic sniper- and mortar-location systems for field units is commended as an immediate response by SEDD to an urgent Army problem. The use of acoustic impulse localization addresses a significant problem in countermortar operations in a terrorist context: that of making engagement decisions and acting on them before the enemy mortar crew disperses. It might be possible for SEDD to help with this problem by developing a real-time information display and communication system that could be kept sufficiently updated with friendly force locations and collateral-damage avoidance zones to enable timely decisions on artillery engagement and effective prepositioning or ad hoc assignment of maneuver elements for countermortar operations in areas where collateral-damage potential prevents use of artillery. Contributions to the Broader Community SEDD does an excellent job of coordinating its research with the broader scientific community. It has an extensive record of publication and patents, with presentations at appropriate conferences and workshops. For example, SEDD scientists and engineers were involved with and published at the Institute of Electrical and Electronics Engineers (IEEE) Microwave Week and at the Government Microsystems Applications Conference. The status and recognition of SEDD in the community at large is reflected in the honors awarded to SEDD personnel. In the past 2 years, SEDD staff have been elected fellows of the IEEE, the Interna- tional Society for Optical Engineering (SPIE), and the Washington Academy of Sciences. 

SENSORS AND ELECTRON DEVICES DIRECTORATE 25 RELEVANCE OF CROSSCUTTING ISSUES TO THIS DIRECTORATE A number of projects within SEDD, such as image processing and acoustic sensing, make extensive use of computation and modeling. It would be beneficial to this directorate to expand the use of computational science and modeling. Additional modeling activities would prove useful in the develop- ment of semiconductor devices such as quantum cascade lasers and quantum well infrared photodetec- tors, as well as sensors, microwave and millimeter wave systems, and even fuel cell design. Information security is relevant to SEDD in areas such as quantum cryptography and wireless communications. The nanotechnology crosscutting initiative offers significant interdirectorate opportunities. SEDD has associated activities in molecular electronics, quantum-effect devices, and advanced materials.