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The 'Kinetic Stabilizer' has been proposed as a means of MHD stabilizing an axisymmetric tandem mirror system. The K-S concept is based on theoretical studies by Ryutov, confirmed experimentally in the Gas Dynamic Trap experiment in Novosibirsk. In the K-S beams of ions are directed into the end of an 'expander' region outside the outer mirror of a tandem mirror. These ions, slowed, stagnated, and reflected as they move up the magnetic gradient, produce a low-density stabilizing plasma. At the Lawrence Livermore National Laboratory we have been conducting theoretical and computational studies of the K-S Tandem Mirror. These studies have employed a low-beta code written especially to analyze the beam injection/stabilization process, and a new code SYMTRAN (by Hua and Fowler) that solves the coupled radial and axial particle and energy transport in a K-S TM. Also, a 'legacy' MHD stability code, FLORA, has been upgraded and employed to benchmark the injection/stabilization code and to extend its results to high beta values. The FLORA code studies so far have confirmed the effectiveness of the K-S in stabilizing high-beta (40%) plasmas with stabilizer plasmas the peak pressures of which are several orders of magnitude smaller than those of the confined plasma.more » Also the SYMTRAN code has shown D-T plasma ignition from alpha particle energy deposition in T-M regimes with strong end plugging. Our studies have confirmed the viability of the K-S-T-M concept with respect to MHD stability and radial and axial confinement. We are continuing these studies in order to optimize the parameters and to examine means for the stabilization of possible residual instability modes, such as drift modes and 'trapped-particle' modes. These modes may in principle be controlled by tailoring the stabilizer plasma distribution and/or the radial potential distribution. In the paper the results to date of our studies are summarized and projected to scope out possible fusion-power versions of the K-S T-M« less

The Kinetic Stabilizer, employing injected and mirror-reflected ion beams, represents a method for stabilizing axisymmetric mirror and tandem mirror systems. Building on earlier work, this paper presents further calculations on the concept and explores some new options that promise to enhance its capabilities.

Arising out of research at the Lawrence Livermore National Laboratory on passive magnetic bearings, a new magnetic levitation system, the Inductrack, has been developed and tested at model scale. The system employs special arrays of permanent magnets (Halbach arrays) on the moving car. The magnetic field from the arrays induces repelling currents in a close-packed array of shorted circuits in the track. Above a low transition speed (a few kilometers per hour), levitation forces approach a constant value, while drag forces decrease inversely with speed, with L/D reaching 200:1 or more at operating speeds. The high magnetic efficiency of the Halbach arrays, plus the use of close-packed track circuits, results in levitating forces approaching 40 metric tonnes per square meter (using NdFeB permanent magnet arrays, whose weight in typical cases is a few percent of the levitated weight). The system is passively stable: only motion is required for levitation. Failure of the drive system only results in the train slowing down and settling onto auxiliary wheels at a low speed. A detailed theoretical analysis of the Inductrack was made, on the basis of which a small-scale model was constructed and operated. The Laboratory is building a new small-scale model system (under NASA sponsorship) to demonstrate the acceleration rates and speeds (10-g and Mach 0.4 in the model) needed to magnetically launch rockets.

This Resource Letter is intended to introduce the reader to the history of fusion research, and to provide references covering the research since its first beginnings and up to the present for those who wish to dig deeper.

A summary of the attractive characteristics of mirror devices is presented. Recent progress in development of axisymmetric mirror devices is described. Potentialities of mirrors as a basis for D{sup 3}He fusion power generators and high flux neutron sources for fusion material tests are discussed. 16 refs., 2 figs.

A small-scale model track of a new type of magnetic levitation system (dubbed the ``Inductrack`` system), and a passively magnetically levitated cart, has been designed, constructed and operated. The track consists of a close-packed array of rectangular levitation coils, 15 centimeters in width transversely and 20 meters in length. The array of coils is inductively loaded above and below its lower horizontal section with ferrite tiles. Paralleling the levitation coils on each side are aluminum-channel rails on which ride auxiliary wheels attached to the cart. The cart has, on its lower surface and on its sides, fore and aft, special arrays (``Halbach arrays``) of permanent magnet bars that produce a strong periodic magnetic field below the cart. This magnetic field, when the cart is in motion, induces repelling currents in the Inductrack coils, levitating it and centering it transversely. When mechanically launched (with a pulley- and-weight system) at speeds substantially above a ``transition speed`` of about 2 meters per second, the cart levitated and flew stably down the track, settling to rest on its wheels near the end of the track. In the last phase of the program an electromagnetic launching section consisting of another array of coils, connected to pulse-driver circuits, was added at the beginning of the track. Aided by an initial launch (from stretched ``bungee`` cords), this electromagnetic launching system was operated successfully, resulting again in levitation and subsequent stable flight of the cart.

Back-reflections from a target, lenses, etc. can gain energy passing backwards through a laser just like the main beam gains energy passing forwards. Unless something blocks these back-reflections early in their path, they can seriously damage the laser. A Mechanical Beam Isolator is a device that blocks back-reflections early, relatively inexpensively, and without introducing aberrations to the laser beam.

Magnetic confinement systems that use externally generated magnetic fields can be divided topologically into two classes:“closed”and“open”, The tokamak, the stellarator, and the reversed-field-pinch approaches are representatives of the first category, while mirror-based systems and their variants are of the second category. While the recent thrust of magnetic fusion research, with its emphasis on the tokamak, has been concentrated on closed geometry, there are significant reasons for the continued pursuit of research into open-ended systems. The paper discusses these reasons, reviews the history and the present status of open-ended systems, and suggests some future directions for the research.

This report describes theoretical and experimental investigations of a new approach to the problem of the magnetic levitation of a moving object. By contrast with previously studied levitation approaches, the Inductrack concept concept represents a simpler, potentially less expensive, and totally passive means of levitating a high-speed train. It may also be applicable to other areas where simpler magnetic levitation systems are needed, for example, high-speed test sleds for crash testing applications, or low-friction conveyer systems for industrial use.

This report describes the design of a passive magnetic bearing system to be used in electromechanical batteries (flywheel energy storage modules) suitable for vehicular use. One or two such EMB modules might, for example, be employed in a hybrid-electric automobile, providing efficient means for power peaking, i.e., for handling acceleration and regenerative braking power demands at high power levels. The bearing design described herein will be based on a ''dual-mode'' operating regime.

As a bonus from an existing LDRD-supported project (Electromechanical Battery Research and Development) a new concept for the magnetic levitation of a moving object evolved. To initiate a study of the merits of the concept mid-year ``seed money`` LDRD funding was provided. The FY94 activities resulted in a preliminary evaluation of the merits of this concept through calculations, laboratory measurements, and the design of a simple test model. There is now considerable international interest in the ``Maglev`` concept for highspeed trains. Wear, rolling friction, and speed limitations of conventional rail technology make this technology unsuitable for such trains, whence the use of magnetic levitation. In present Maglev trains, however, such as those constructed in Germany and Japan, servo-controlled magnetic systems are required, involving sensor and control circuitry and non-trivial on-board power requirements. In such systems the failure of a control system can have serious consequences, so that redundant systems may be required, thus adding to the cost and complexity. It would be highly desirable to replace the present ``active``, servo-controlled magnetic levitation systems with a totally passive one, one for which neither control circuits nor on-board power would be required. Failure of such a system could be made to be much more benign in its consequences than for servo-controlled ones, and the cost, particularly of the on-board equipment, might be greatly reduced.

New materials and new design concepts are being incorporated in a new approach to an old idea -- flywheel energy storage -- to create an important alternative to the electrochemical storage battery for use in electric vehicles or for stationary applications, such as computer back-up power or utility load-leveling. We visualize such EMBs (electromechanical batteries) as being modular in character, with small (1--5 kWh) modules being used for power-conditioning and for vehicular use, and paralleled 25 kWh modules being used for bulk storage, i.e., load-leveling, applications. In a funded program at the Laboratory two fractional kWh, 200 kW (design peak power) modules have been constructed and subjected to shake-down testing. Their design for high peak power was prompted by awareness of a particular commercial need, as a component in a power-line conditioning device. In addition to such stationary applications, the high power capability of our EMB designs makes them attractive for use in hybrid-electric vehicles. Important elements of the LLNL program include the development of passive magnetic bearings and the application of new high-efficiency permanent magnet arrays to an ironless generator/motor. Use of these particular elements, together with a multi-ring design for the flywheel rotor, is particularly conducive to amore » systemic approach to the design of an EMB module. These particular design developments have been motivated by the economic issues of simplification, lowered cost, and extended maintenance-free service life.« less

Numerical simulations and experimental studies have been made related to the possibility of employing an externally imposed electrostatic potential wave to separate isotopes. This wave/ion interaction is a sensitive function of the wave/ion difference velocity and for the appropriate wave amplitude and wave speed, a lighter faster isotope will be reflected by the wave to a higher energy while leaving heavier, slower isotopes virtually undisturbed in energy--allowing subsequent ion separation by simple energy discrimination. In these experiments, a set of some 200 individual electrodes, which surrounded a microamp beam of neon ions, was used to generate the wave. Measurements of the wave amplitudes needed for ion reflection and measurements of the final energies of those reflected ions are consistent with values expected from simple kinetic arguments and with the more detailed results of numeric simulations.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This report was prepared in late 1965 at the request of the U.S. House-Senate Joint Committee on Atomic Energy (JCAE) to review its program on controlled thermonuclear research (CTR), now called just “fusion energy research.” It was transmitted to them on June 11, 1966 by then chairman of the U.S. Atomic Energy Commission (AEC) Glenn T. Seaborg. The AEC is the predecessor agency of the current U.S. Department of Energy (DOE). The report has previously only been available as AEC report TID-23277. This version of the report is complete except for the omission of lengthy discussions of the then current fusion research activities at various AEC sites. This paper includes, as does the original report, a copy of Seaborg’s June 11, 1966 transmittal letter and, as appendices, copies of a 1962 review of the fusion program by the AEC’s General Advisory Committee (GAC), a review of the Policy Paper by a special 1965 AEC committee, prior to its submittal to the JCAE, comments on the report by the GAC and the President’s Science Advisory Committee, and the charter for then newly established CTR Standing Committee.

In the fields of controlled fusion research and high-energy nuclear physics it is becoming evident that means for the efficient generation of very high magnetic fields must be sought. Since ferromagnetic materials are of no help at the required fields of 105 gauss, one can only rely on the use of air core coils, so that the fields which can be reached depend only on the ampere-turns achievable and simple geometrical factors. In this case the limitations on attainable fields usually come down to a question of available electrical power, or, more fundamentally, to limitations imposed by heating of the coil conductors and problems of heat transfer within the coil. For laboratory — sized magnets, the limit is reached in magnets such as the Bitter magnet, where the ultimate limit is nearly reached in power density and heat transfer while achieving steady fields of 105 gauss in volumes of the order of 1 liter.

The attenuation of (319\ifmmode\pm\else\textpm\fi{}4)-Mev photons in liquid hydrocarbons has been measured and has been used to infer the cross section for pair production in the field of the orbital electrons (triplet production).Targets of benzene (${\mathrm{C}}_{6}$${\mathrm{H}}_{6}$) and cyclohexane (${\mathrm{C}}_{6}$${\mathrm{H}}_{12}$) were used in good geometry. A pair spectrometer with three fast counter channels was used to measure the intensity of the transmitted photon beam. The synchrotron was monitored with a modified pair spectrometer that was sensitive only to the bremsstrahlung spectrum above 300 Mev.The total absorption cross sections in hydrogen and carbon at 319 Mev have been found to be 18.0\ifmmode\pm\else\textpm\fi{}1.8 mb per hydrogen atom, and 321.1\ifmmode\pm\else\textpm\fi{}2.8 mb per carbon atom, respectively.Subtraction of the theoretical nuclear pair and electron Compton cross sections and the experimental photomeson cross sections in hydrogen from the total hydrogen absorption cross section gives 6.8\ifmmode\pm\else\textpm\fi{}1.8 mb for the experimental triplet cross section, as compared with the theoretical value of 7.68 mb. Similarly, when one subtracts the cross sections for competing processes in carbon, one gets for the triplet cross section at 319 Mev the value 46.6\ifmmode\pm\else\textpm\fi{}6.4 mb, compared with the theoretical value of 44.4 mb. The large uncertainty in the carbon triplet cross section is due to uncertainties in the cross sections for the competing processes.

The correlation and theoretical analysis of a large number of transmission measurements made in the Potomac River and Chesapeake Bay areas warrants the conclusions which follow. Given a source of audiofrequency sound in water, the sound pressure level which may be measured at appreciable distances will be influenced in a complicated way by the boundaries, especially by the bottom. The sea bottom may be classified by its behavior for sound as “soft,” “hard,” or intermediate in character. Specifically, the velocity of sound and the density of the bottom may be estimated from acoustic measurements (hydrophone soundings and range runs), by sampling, and from hydrographic data. The effect of the boundaries on sound propagation from a ship‐mounted source may be determined from an analysis of the normal modes of vibration of the acoustic system of the sea between surface and bottom. The analysis is particularly effective for frequencies at which the wave‐lengths are comparable to the physical dimensions of the s...