Impact of The High-Energy Product Materials on Magnetic Circuit Design
- PDF / 1,847,140 Bytes
- 28 Pages / 420.48 x 639 pts Page_size
- 50 Downloads / 141 Views
IMPACT OF THE HIGH-ENERGY PRODUCT MATERIALS ON MAGNETIC CIRCUIT DESIGN HERBERT A. LEUPOLD, ERNEST POTENZIANI II, JOHN P. CLARKE, AND DOUGLAS J. BASARAB Electronics Technology and Devices Laboratory, Fort Monmouth, NJ 07703-5000 ABSTRACT Many devices that employ magnetic fields are encumbered by massive solenoids with their equally bulky power supplies or by inefficient permanentmagnet structures designed for use with obsolescent magnet materials. This paper describes how the high-energy product materials are employed in several structures to afford mass and bulk reductions of an order of magnitude or more. Also discussed are novel designs that are not attainable with the older materials such as the alnicos. Substitution of solenoids with permanent magnets also eliminates considerable energy consumption and the attendant problems arising from generation of heat. In many cases, all this is accomplished within leakage-free systems. Among the designs described are: nuclear magnetic resonance imagers; cylindrical solenoidal field structures for klystrons and nonperiodic field TWT's; cylindrical field structures with arbitrary axial gradients for advanced gyrating beam sources; annular field sources for high harmonic gyrotrons; helical transverse field sources for circularly polarized radiation sources; miniature periodic permanent-magnet configurations; and clad permanent-magnet circuits for biasing fields in millimeter-wave filters. Where alternate designs exist, they are compared with regard to performance, bulk, and economy. All of the structures are in various stages of design and construction, and, for completed structures, comparisons are made between theoretical projections and actual performance. INTRODUCTION While the rare-earth permanent magnets (REPM) afford greatly enhanced performance when substituted for older magnets in conventional devices, such employment amounts to mere improvements in degree, rather than the revolution in kind of which these remarkable materials are capable. Not only do their high-energy products enable them to supply higher fields to greater volumes with less material, but their extreme magnetic rigidity under the influence of large antiparallel (coercivity) and orthogonal (anisotropy) fields greatly simplifies magnet design and fabrication. It also makes possible efficient permanent-magnet configurations that are unviable with conventional permanent magnets. A number of such structures have been designed at the U. S. Army Electronics Technology and Devices Laboratory (ETDL) for use in a variety of light, compact, millimeter-wave, microwave, and optical devices for electronbeam lenses; Faraday rotators; radiation sources; amplifiers; filters; isolators; and circulators. A selection of these structures is described in this paper to illustrate the design methods appropriate for high-energy product magnet materials, to suggest further uses and development of such devices and to highlight future research on permanent magnets needed to further expand their efficacy and range of usefulness
Data Loading...
