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This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) program, is dated 6 April 2010 and is part of a series of advanced technology reports produced in FY 2009. It reviews proposed laboratory generators and detectors of high-frequency gravitational waves for communications. It favors an infrared-excited molecules transmitter and the Li-Baker detector, estimating about 1.9 million bits per second over 7,000 km through the Earth. It also discusses timing standards and interplanetary navigation uses.
“Cooper”1 page
UNCLASSIFIED/ ,'1"1!11'- l!ll"l"U!llltt l!l!ii! s,11!¥ quantitative estimate would be needed to ensure that the non-uniformity is not serious in the present application, but this is not expected to be a problem since field non- uniformity just produces non-uniform PPF generation in the interaction volume. The fractal membrane reflectors would still focus all the PPF at the receivers. The design tradeoff will be whether one or two large magnets are more cost-effective than a larger number of smaller magnets. The design effort will be divided into two major sub-tasks: off-the-shelf electromagnets currently available, and emerging-technology proposed magnets that may become available during the construction phase of the HFGW detector. DDl.7.1 Off-the-shelf hardware: Excepting major installations, iron-core magnets are limited to around 2T over small volumes so that superconducting magnets are expected to be used here. Cryogen-free (more accurately, the cryogen is completely enclosed and re-cycled each time the magnet is cooled for use) superconducting magnets producing fields up to 16T are available commercially from a number of manufacturers including Scientific Magnetics, Oxford Instruments, and Cryogenic Ltd. (all UK). As examples, Oxford Instruments can supply magnets producing 9T in a 20cm bore, and ST in a 1m bore. Typically, cooling is provided by an integral Gifford- McMahon cryo-cooler at 4.2K. Use of a cryogen-free "dry" magnet means that there are no cold seals to be a source of leaks. DDl.7.2 Emerging technology: Since the detection PPF signal is directly proportional to the static magnetic field value, the detector sensitivity will be increased by using larger fields than currently-available commercial designs permit. To this end we will investigate the feasibility of co-developing with a third-party (for example, National High Magnetic Field Laboratory, Tallahassee, Florida) a custom-made high-field design capable of up to 35T (Bird, 2004), which may be realizable during the construction phase of the Li-Baker detector. If successful, achieving this value of magnetic field would improve the sensitivity of the Li-Baker detector by an order of magnitude. In this case, if a separate refrigeration system is required, the specification would include cryogen level-monitoring to ensure safe auto-rundown of the superconducting magnet if the helium level falls below a pre-set value, to reduce the danger associated with cryogenic-system related magnet failure .. I Systems Engineering Tasks Following the completion of the Li-Baker detector development tasks, plans and specifications will be drawn up by LSU in collaboration with TSC. Since overlap of tasks is possible, approximately 18 months will be allowed for the detector design, and approximately 8 months for the preparation of plans and specifications. With approximately two months overlap of the major tasks, a total of two years will be scheduled for the detector's design and development of the plans and specifications. Fig. 4.1a shows a Gannt chart for scheduling the project. For any large engineering project, coordination among investigators is important for the development of a coherent, unified design. This is the role of systems engineering tasks, depicted at the top of Fig. 4.1a. In the present case, the development of the detector will demand the close coordination of the detection link budget very early on, in order to carefully guide the component design for each of the component areas, and to ensure that the sensitivity goals can be met. This task culminates in a review of the predicted signal-to- noise ratio. A follow-on to this task is the development of key component requirements Interface requirements development is the next level of detail in systems engineering 50 UNCLASSIFIED/ ,'P8"1 8PPl81il.k Wliili &•lkl/'
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 57 pages are in the text index: search them above, or from the library's search.