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in subjects: "Magnetic Fields"

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Numerical simulation of a short RFQ resonator using the MAFIA codes

The electrical characteristics of a short (2{beta}{lambda}=0.4 m) resonator with large modulation (m=4) have been studied using the three dimensional codes, MAFIA. The complete resonator, including the modulated electrodes and a complex support structure, has been simulated using {approximately} 350,000 mesh points. Important characteristics studied include the resonant frequency, electric and magnetic fields distributions, quality factor and stored energy. The results of the numerical simulati… more

Date: January 1, 1991

Creator: Wang, H.; Ben-Zvi, Ilan; Jain, A.; Paul, P. (State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The limited streamer tubes system for the SLD warm iron calorimeter

The SLD detector at the Stanford Linear Accelerator Center is a general purpose device for studying e{sup +}{epsilon}{sup {minus}} interaction at the Z{sup 0}. The SLD calorimeter system consists of two parts: a lead Liquid Argon Calorimeter (LAC) with both electromagnetic (22 radiation lengths) and hadronic sections (2.8 absorption lengths) housed inside the coil, and the Warm Ion limited streamer tubes Calorimeter (WIC) outside the coil which uses as radiator the iron of the flux return for t… more

Date: January 1, 1992

Creator: Benvenuti, A. C.; Camanzi, B.; Piemontese, L.; Zucchelli, P.; Calcaterra, A.; De Sangro, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A unified theory of resonant excitation of kinetic ballooning modes by energetic ions/alpha particles in tokamaks

A complete theory of wave-particle interactions is presented whereby both circulating and trapped energetic ions can destabilize kinetic ballooning modes in tokamaks. Four qualitatively different types of resonances, involving wave-precessional drift, wave-transit, wave-bounce, and precessional drift-bounce interactions, are identified, and the destabilization potential of each is assessed. For a characteristic slowing-down distribution function, the dominant interaction is that which taps thos… more

Date: October 1, 1991

Creator: Biglari, H. & Chen, L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Magnetic field, closed orbit, and energy measurement in the Bevatron

This report provides the information necessary for a better evaluation of particle energy in the Bevatron. Previously, the nominal magnetic field value and radius were used to calculate the value for the kinetic energy of the particle. This value was good to a few percent. Today, more and more experimenters would like to know the energy to a more precise value. To this end, corrections to the measured magnetic field values and the radial closed orbit are provided.

Date: November 1, 1981

Creator: Crebbin, K. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Non-linear instability of DIII-D to error fields

Otherwise stable DIII-D discharges can become nonlinearly unstable to locked modes and disrupt when subjected to resonant m = 2, n = 1 error field caused by irregular poloidal field coils, i.e. intrinsic field errors. Instability is observed in DIII-D when the magnitude of the radial component of the m = 2, n = 1 error field with respect to the toroidal field is B{sub r21}/B{sub T} of about 1.7 {times} 10{sup {minus}4}. The locked modes triggered by an external error field are aligned with the … more

Date: October 1, 1991

Creator: La Haye, R. J. & Scoville, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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An update on passive correctors for the SSC dipole magnets

The concept of correction of the magnetization sextupole became a topic of discussion as soon as it was realized that superconductor magnetization could have a serious effect on the SSC beam during injection. Several methods of correction were proposed. These included (1) correction with active bore tube windings like those on the HERA machine which correct out magnetization sextupole and the sextupole due to iron saturation, (2) correction with persistent sextupole windings mounted on the bore… more

Date: May 1, 1991

Creator: Green, Michael A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Environmental assessment for the Satellite Power System (SPS) Concept Development and Evaluation Program (CDEP). [Microwave and non-microwave health and ecological assessment]

In the satellite power system (SPS), satellites in geosynchronous earth orbit would collect solar energy in space, convert it to microwaves, and transmit the microwaves to receiving antennas (rectennas) on earth. At the rectennas, the microwave energy would be converted to electricity. This SPS environmental assessment considers the microwave and nonmicrowave effects on the terrestrial environment and human health, atmospheric effects, and effects on electromagnetic systems. No environmental pr… more

Date: August 1, 1980

Creator: Valentino, A.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Estimates of SASE power in the short wavelength region

Given a sufficiently bright electron beam, the self-amplified-spontaneous emission (SASE) can provide gigawatts of short wavelength coherent radiation. The advantages of SASE approach are that is requires neither optical cavity nor an imput seed laser. In this note, we estimate the peak power performance of SASE for wavelengths shorter than 1000 {Angstrom}. At each wavelength, we calculate the saturated power from a uniform parameter undulator and the enhanced power from a tapered undulator. Th… more

Date: March 1, 1992

Creator: Kim, Kwang-Je.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Internal magnetic fields in hcp-iron

The magnetic behavior of hcp-Fe (epsilon iron) has been investigated by the Moessbauer Effect over a wide range of temperature T, pressure P, and applied magnetic field H/sub 0/. The internal field H/sub i/ of the induced moment is given by H/sub i/ = 0.20 +- .01 H/sub 0/ and is independent of T and P. Enhanced paramagnetism is suggested as the most likely origin for a contribution of this magnitude to H/sub i/.

Date: January 1, 1982

Creator: Taylor, R. D.; Cort, G. & Willis, J. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Detection of plasma equilibrium shifts with fiber optic sensing of image currents

The radial equilibrium position of Reverse Field Pinch experiments is determined by the j x B force on the plasma. The current density is that of the toroidal plasma current and the B field is the vertical magnetic field which is present in the plasma. This magnetic field is the result of several components. The main field, generated by the toroidal current windings, is corrected by adjustable trim windings to achieve a desired equilibrium position. There is an additional component to the field… more

Date: January 1, 1988

Creator: Forman, P.R.; Jahoda, F.C. & Miller, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sources of polarized ions and atoms

In this presentation we discuss methods of producing large quantities of polarized atoms and ions (Stern-Gerlach separation, optical pumping, and spin-exchange) as well as experimental methods of measuring the degree of polarization of atomic systems. The usefulness of polarized atoms in probing the microscopic magnetic surface properties of materials will also be discussed. 39 refs., 5 figs., 2 tabs.

Date: January 1, 1988

Creator: Cornelius, W.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Optimization of microchannel plate multipliers for tracking minimum-ionizing particles

The progress in development of special Microchannel Plates for particle tracking is reported. The requirements of (1) high spatial resolution; (2) high density of information; and (3) rate capability were found to be satisfied in a thick Microchannel Plate with a CsI coating operating in a focusing magnetic field. The measurements of the Microchannel Plate detection efficiency, gain and noise are presented for several detectors. The pictures of the passage and interaction of the high energy cha… more

Date: January 1, 1981

Creator: Oba, K.; Rehak, P. & Potter, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Close-in Magnetic Fields of a Lightning Return Stroke

This report address a close-in magnetic fields of a lightning return stroke.

Date: June 1, 1975

Creator: Jones, R. D. & Watts, H. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Performance of trim coils made by a novel method

A precision, automated method of manufacturing trim coils based on printed circuit technology has been developed. Excellent quench performance and increased radiation resistance have been achieved in recently-tested models of sextupole trim coils developed for operation inside 40 mm-aperture SSC Main Collider dipoles. 6 refs., 2 figs.

Date: January 1, 1991

Creator: Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Static magnetic fields: A summary of biological interactions, potential health effects, and exposure guidelines

Interest in the mechanisms of interaction and the biological effects of static magnetic fields has increased significantly during the past two decades as a result of the growing number of applications of these fields in research, industry and medicine. A major stimulus for research on the bioeffects of static magnetic fields has been the effort to develop new technologies for energy production and storage that utilize intense magnetic fields (e.g., thermonuclear fusion reactors and superconduct… more

Date: May 1, 1992

Creator: Tenforde, T.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Results of magnetic field measurements of 40 mm aperture 17-m long SSC model collider dipole magnets

Magnetic field measurements have been made on twelve 17 m-long, 40 mm-aperture R D superconducting dipoles. Data on dipole field strength, multipole coefficients, and alignment have been obtained. The data indicate that the magnets as built are generally within the expectations for this design. 7 refs., 5 figs.

Date: January 1, 1991

Creator: Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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High-field bipolar loss measurement apparatus

An apparatus was constructed to measure dissipation in superconducting wire in high alternating fields. The apparatus will be used to make measurements on conductors which must operate in fields up to 7.0 T and rates of field change up to 15 T/s. The magnet for this facility is wound of uninsulated, 15 strand Rutherford cable in which the strand is a 0.812 mm diameter, fully mixed matrix, Cu plus CuNi, multifilament NbTi conductor. The coil is wound in a bath cooled configuration with an overal… more

Date: January 1, 1980

Creator: Thullen, P.; Weldon, D. & Wollan, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Alternative dipole magnets for ISABELLE

A dipole magnet, intended as a possible alternative for the ISABELLE main-ring magnet, was designed at LBL. Three layers of FNAL Doubler/Saver conductor were used. Two 1.3-m-long models were built and tested, both with and without an iron core, and in both helium I and helium II. The training behavior, cyclic energy loss, point of quench initiation, and quench velocity were determined. A central field of 6.5 tesla was obtained in He I (4.4 K), and 7.6 tesla in He II (1.8K).

Date: May 1, 1982

Creator: Taylor, C.; Althaus, R.; Caspi, S.; Gilbert, W.; Hassenzahl, W.; Meuser, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Nonlinear gyrokinetic theory for finite-BETA plasmas

A self-consistent and energy-conserving set of nonlinear gyrokinetic equations, consisting of the averaged Vlasov and Maxwell's equations for finite-..beta.. plasmas, is derived. The method utilized in the present investigation is based on the Hamiltonian formalism and Lie transformation. The resulting formation is valid for arbitrary values of k/perpendicular//rho//sub i/ and, therefore, is most suitable for studying linear and nonlinear evolution of microinstabilities in tokamak plasmas as we… more

Date: February 1, 1988

Creator: Hahm, T. S.; Lee, W. W. & Brizard, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Time-Dependent Two-Dimensional Radiation Hydrodynamics of Accreting Matter Onto Highly Magnetized Neutron Stars

We present for the first time, the self-consistent solution of the two-dimensional, time-dependent equations of radiation-hydrodynamics governing the accretion of matter onto the highly magnetized polar caps of luminous x-ray pulsars. The calculations show a structure in the accretion column very different from previous one-zone uniform models. We have included all the relevant magnetic field corrections to both the hydrodynamics and the radiative transport. We include a new theory for the diff… more

Date: November 24, 1989

Creator: Klein, R.I. (California Univ., Los Angeles, CA (USA). Dept. of Astronomy Lawrence Livermore National Lab., CA (USA) California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics) & Arons, J. (California Univ., Berkeley, CA (USA). Dept. of Astronomy California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics CEA Centre d'Etudes Nucleaires de Saclay, 91 -

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Interaction of biological systems with static and ELF electric and magnetic fields

Although background levels of atmospheric electric and geomagnetic field levels are extremely low, over the past several decades, human beings and other life forms on this planet have been subjected to a dramatically changing electromagnetic milieu. An exponential increase in exposure to electromagnetic fields has occurred, largely because of such technological advances as the growth of electrical power generation and transmission systems, the increased use of wireless communications, and the u… more

Date: January 1, 1987

Creator: Anderson, L.E.; Kelman, B.J. & Weigel, R.J. (eds.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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X-Y spacial distribution experiments with Parmela or, what I did on my summer vacation

Experiments using the Parmela simulation program predict that the potentially uneven spacial distributions in the electron beam generated by laser emission from the photo cathode gun has no appreciable effect on the beam outcome when compared to a the more uniform thermionic gun. 23 figs., 4 tabs.

Date: August 1, 1991

Creator: Houston, J.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Anomalous rf magnetoresistance in copper at 4/degree/K

We have measured the effect of a magnetic field on the surface resistance of polycrystalline Cu at f = 1.2 GHz and at 4.4/degree/K; under these conditions the surface resistance is well into the anomalous skin effect regime but has not reached its limiting value. We find that the transverse and longitudinal magnetoresistance are an order of magnitude smaller than the DC magnetoresistance and depend quadratically on the field. At low fields we observe a decrease in surface resistance with increa… more

Date: March 1, 1988

Creator: Halama, H. J.; Prodell, A. G.; Rogers, J. T.; De Panfilis, S.; Melissinos, A. C.; Moskowitz, B. E. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Extracting maximal information on positive muon diffusion in metals

It is discussed how combining zero- and longitudinal-field ..mu..SR can give more information on the motion of the ..mu../sup +/ in the target than zero-field studies alone.

Date: January 1, 1982

Creator: Leon, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department