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Electromagnetic dissociation of radioactive heavy-ion beams
Based on our experience with electromagnetic dissociation of relativistic stable ions, we discuss the prospects for experiments with beams of relativistic radioactive heavy ions.
Electromagnetic dissociation of relativistic Si via giant dipole resonance
A detailed study of the electromagnetic dissociation of {sup 28}Si in extremely peripheral collisions at 14.6 GeV/nucleon was carried out with {sup 28}Si projectiles interacting on Pb, Sn, Cu and Al targets. The excitation energy is determined by measurements of the invariant mass of the excited system. We examine the decay channels 1p+{sup 27}Al, l+{sup 27}Si and 2p+{sup 26}Mg. The excitation energy distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear cross sections. No evidence for double photon excitation of {sup 28}Si is observed.
Electromagnetic dissociation of relativistic {sup 28}Si by nucleon emission
A detailed study of the electromagnetic dissociation of {sup 28}Si by nucleon emission at E{sub lab}/A = 14.6 (GeV/nucleon was carried out with {sup 28}Si beams interacting on {sup 208}Pb). {sup 120}Sn. {sup 64}C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge Z{sub T} and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of {sup 28}Si {yields} p+{sup 27}Al and {sup 28}Si {yields} n+{sup 27}Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in {sup 28}Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear {sup 28}Si({sub {gamma},p}){sup 27}Al and {sup 28}Si({sub {gamma},n}){sup 27}Si. The possibilities of observing double giant dipole resonance excitations in {sup 28}Si have been investigated with cross section measurements as well as with excitation energy reconstruction.
Electromagnetic dissociation of relativistic [sup 28]Si by nucleon emission
A detailed study of the electromagnetic dissociation of [sup 28]Si by nucleon emission at E[sub lab]/A = 14.6 (GeV/nucleon was carried out with [sup 28]Si beams interacting on [sup 208]Pb). [sup 120]Sn. [sup 64]C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge Z[sub T] and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of [sup 28]Si [yields] p+[sup 27]Al and [sup 28]Si [yields] n+[sup 27]Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in [sup 28]Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear [sup 28]Si([sub [gamma],p])[sup 27]Al and [sup 28]Si([sub [gamma],n])[sup 27]Si. The possibilities of observing double giant dipole resonance excitations in [sup 28]Si have been investigated with cross section measurements as well as with excitation energy reconstruction.
Electromagnetic dissociation of sup 238 U in heavy-ion collisions at 120 MeV/A
This thesis describes a measurement of the heavy-ion induced electromagnetic dissociation of a 120 MeV/A {sup 238}U beam incident on five targets: {sup 9}Be, {sup 27}Al, {sup nat}Cu, {sup nat}Ag, and {sup nat}U. Electromagnetic dissociation at this beam energy is essentially a two step process involving the excitation of a giant resonance followed by particle decay. At 120 MeV/A there is predicted to be a significant contribution of the giant quadrupole resonance to the EMD cross sections. The specific exit channel which was looked at was projectile fission. The two fission fragments were detected in coincidence by an array of solid-state {Delta}E-E detectors, allowing the changes of the fragments to be determined to within {plus minus} .5 units. The events were sorted on the basis of the sums of the fragments' charges, acceptance corrections were applied, and total cross sections for the most peripheral events were determined. Electromagnetic fission at the beam energy of this experiment always leads to a true charge sum of 92. Due to the imperfect resolution of the detectors, charge sums of 91 and 93 were included in order to account for all of the electromagnetic fission events. The experimentally observed cross sections are due to nuclear interaction processes as well as electromagnetic processes. Under the conditions of this experiment, the cross sections for the beryllium target are almost entirely due to nuclear processes. The nuclear cross sections for the other four targets were determined by extrapolation from the beryllium data using a geometrical scaling model. After subtraction of the nuclear cross sections, the resulting electromagnetic cross sections are compared to theoretical calculations based on the equivalent photon approximation. Systematic uncertainties are discussed and suggestions for improving the experiment are given.
Electromagnetic dissociation of {sup 238}U in heavy-ion collisions at 120 MeV/A
This thesis describes a measurement of the heavy-ion induced electromagnetic dissociation of a 120 MeV/A {sup 238}U beam incident on five targets: {sup 9}Be, {sup 27}Al, {sup nat}Cu, {sup nat}Ag, and {sup nat}U. Electromagnetic dissociation at this beam energy is essentially a two step process involving the excitation of a giant resonance followed by particle decay. At 120 MeV/A there is predicted to be a significant contribution of the giant quadrupole resonance to the EMD cross sections. The specific exit channel which was looked at was projectile fission. The two fission fragments were detected in coincidence by an array of solid-state {Delta}E-E detectors, allowing the changes of the fragments to be determined to within {plus_minus} .5 units. The events were sorted on the basis of the sums of the fragments` charges, acceptance corrections were applied, and total cross sections for the most peripheral events were determined. Electromagnetic fission at the beam energy of this experiment always leads to a true charge sum of 92. Due to the imperfect resolution of the detectors, charge sums of 91 and 93 were included in order to account for all of the electromagnetic fission events. The experimentally observed cross sections are due to nuclear interaction processes as well as electromagnetic processes. Under the conditions of this experiment, the cross sections for the beryllium target are almost entirely due to nuclear processes. The nuclear cross sections for the other four targets were determined by extrapolation from the beryllium data using a geometrical scaling model. After subtraction of the nuclear cross sections, the resulting electromagnetic cross sections are compared to theoretical calculations based on the equivalent photon approximation. Systematic uncertainties are discussed and suggestions for improving the experiment are given.
An Electromagnetic Drift Instability in the Magnetic Reconnection Experiment (MRX) and its Importance for Magnetic Reconnection
The role which resistivity plays in breaking magnetic field lines, heating the plasma, and plasma field slippage during magnetic reconnection is discussed. Magnetic fluctuations are observed in the MRX (Magnetic Reconnection Experiment) that are believed to provide resistive friction or wave resistivity. A localized linear theory has been proposed for their origin as an obliquely propagating Lower Hybrid Drift Instability. In this paper, the linear theory of the instability is summarized, and the resulting heating and slippage are calculated from quasi-linear theory. Making use of measured amplitudes of the magnetic fluctuations in the MRX the amount of these effects is estimated. Within the experimental uncertainties they are shown to be quite important for the magnetic reconnection process.
Electromagnetic Effects Due to Spin-Orbit Coupling
No Description Available.
Electromagnetic Effects in Relativistic Electron Beam Plasma Interactions
Electromagnetic effects excited by intense relativistic electron beams in plasmas are investigated using a two-dimensional particle code. The simulations with dense beams show large magnetic fields excited by the Weibel instability as well as sizeable electromagnetic radiation over a significant range of frequencies. The possible relevance of beam plasma instabilities to the laser acceleration of particles is briefly discussed. 6 refs., 4 figs.
Electromagnetic effects of plasma disruptions in tokamaks
The tokamak is modeled as typically 100 mutually-coupled toroidal circuits. The self and mutual inductances and the currents and voltages are calculated. Using the calculated currents, the poloidal magnetic field and the electromagnetic forces as functions of space and time are calculated. The major conclusion of the analysis is that the torus sectors should be electrically connected to each other near the plasma. Such connections reduce the structural loads, eliminate arcing, and reduce the induced potentials in the poloidal field coils.
Electromagnetic effects on the FED/INTOR limiter
Electromagnetic effects were among the critical issues of the impurity control system examined in the 1982 FED/INTOR design study. During a plasma disruption, the decaying plasma current induces voltages and currents in the first wall and limiter systems which can produce arcing between limiter segments and large forces and torques on the limiter. The effects of first wall time constant, limiter electrical resistance, and limiter segmentation on the voltages, forces, and torques were studied.
Electromagnetic effects on transportation systems
Electronic and electrical system protection design can be used to eliminate deleterious effects from lightning, electromagnetic interference, and electrostatic discharges. Evaluation of conventional lightning protection systems using advanced computational modeling in conjunction with rocket-triggered lightning tests suggests that currently used lightning protection system design rules are inadequate and that significant improvements in best practices used for electronic and electrical system protection designs are possible. A case study of lightning induced upset and failure of a railway signal and control system is sketched.
Electromagnetic (EM-60) survey in the Panther Canyon Area, Grass Valley, Nevada
Eight frequency domain electromagnetic soundings were measured over the Panther Canyon thermal anomaly in Grass Valley, Nevada. The data were collected with Lawrence Berkeley Laboratory's large moment horizontal loop system (EM-60). At the transmitter site located near the center of the thermal anomaly, square wave currents of up to 70 A were impressed into a fourturn 50 m radius coil at frequencies from 0.033 to 500 Hz. At the eight receiver sites, 0.5 to 1.5 km from the loop, magnetic fields were detected with a three-component SQUID magnetometer and vertical and radial magnetic field spectra were calculated. Data were interpreted with a computer program which fit filled spectra and associated ellipse polarization data to one-dimensional resistivity models and results were compared to interpretations from earlier dipole-dipole resistivity measurements. Comparison of these interpretations indicates fairly close agreement between the two, with both models clearly indicating the presence and dimensions of the conductivity anomaly associated with the thermal zone. Although the dc data was better able to resolve the high resistivity bedrock, the EM-data were able to resolve all major features without distortion at shorter transmitter receiver separations and in about one-third of the field time.
Electromagnetic (EM-69) survey of the McCoy geothermal prospect, Nevada
A frequency-domain electromagnetic survey was conducted at 19 stations over a 200 km/sup 2/ area encompassing the McCoy geothermal prospect, Churchill County, central Nevada. The McCoy area is characterized by high heat flow, mercury mineralization, and recent volcanics. Three horizontal-loop transmitters were used with receivers from 0.5 to more than 4.0 km from the loops. Receiver stations were arranged along a pair of crossing north-south and east-west lines. Data were interpreted first with a simple apparent resistivity formula and then with a least-squares lumped-model inversion program. The rough terrain and complex geology introduce an element of uncertainty to the interpretations.
Electromagnetic energy applied to and gained from lunar materials
Electromagnetic energy may be useful in microwave frequencies for in-situ melting or sintering of lunar regolith. Simple configurations of magnetron or gyrotron tubes might be constructed for unique melting geometries. For energy production, lunar ilmenite has potential applications in photovoltaic devices. 11 refs., 11 figs.
Electromagnetic excitation of nucleon resonances
Theoretical approaches for extracting the {gamma} N {l arrow} {r arrow} {sup *} matrix elements from the data of {gamma} N {r arrow} {pi} N and N(e,e {prime} {pi}) reactions are reviewed. We discuss the physical content of the {Delta} resonance parameters listed in the table of particle properties.
Electromagnetic excitation of nucleon resonances
Theoretical approaches for extracting the {gamma} N {l_arrow} {r_arrow} {sup *} matrix elements from the data of {gamma} N {r_arrow} {pi} N and N(e,e {prime} {pi}) reactions are reviewed. We discuss the physical content of the {Delta} resonance parameters listed in the table of particle properties.
Electromagnetic excitation of nucleon resonances
The status and future prospects of photo- and electroexcitation of nucleon resonances are discussed. Data are compared with calculations within the framework of the constituent quark model. It is shown that measurement of resonance transition amplitudes can be used as a sensitive tool to study the QCD structure of the nucleon.
Electromagnetic experiment to map in situ water in heated welded tuff: Preliminary results
An experiment was conducted in Tunnel Complex G at the Nevada Test Site to evaluate geotomography as a possible candidate for in situ monitoring of hydrology in the near field of a heater placed in densely welded tuff. Alterant tomographs of 200 MHz electromagnetic permittivity were made for a vertical and a horizontal plane. After the 1 kilowatt heater was turned on, the tomographs indicated a rapid and strong drying adjacent to the heater. Moisture loss was not symmetric about the heater, but seemed to be strongly influenced by heterogeneity in the rock mass. The linear character of many tomographic features and their spatial correlation with fractures mapped in boreholes are evidence that drying was most rapid along some fractures. When the heater was turned off, an increase in moisture content occurred around the heater and along the dry fractures. However, this process is much slower and the magnitude of the moisture increase much smaller than the changes observed during heating of the rock. The interpretation of the tomographs is preliminary until they can be processed without the restrictive assumption of straight ray paths for the signals through the highly heterogeneous rock mass. 15 refs., 4 figs.
Electromagnetic exploration system. Progress report
A design for a cost effective, highly flexible, and portable controlled source EM exploration system is presented. The design goals of the CMOS micro-processor based receiver and its companion transmitter are listed. (MHR)
Electromagnetic field analysis of septum magnet for APS positron accumulator ring
This report consists of three parts. The first part describes a numerical analysis method for the electromagnetic field analysis of a septum magnet. A novel improvement to the treatment of exciting currents in the time-domain is proposed. The second part discusses numerical predictions of the electromagnetic characteristics of the APS PAR septum. The time variations of stray field and eddy currents are shown for three magnet designs. The last part explores how decreasing the septum material conductivity affects the stray field. The decrease of conductivity may be caused by an inadequate manufacturing of the septum material. The significance of a high quality septum, or flat interface between copper and iron, is emphasized from a point of view of stray field. An ideal method for joining two different metals without distortion, called HIP (Hot Isostatic Pressing), is introduced and recommended based on the authors` experience.
Electromagnetic field-computation for particle accelerators, today and tomorrow
In this paper, we first review the magnets needed in accelerators, then discuss computations for accelerator magnets performed with present codes, and finally describe a new volume integral code which shows promise, and should be suitable for parallel computation. 9 refs., 10 figs.
Electromagnetic field effects on cells of the immune system: The role of calcium signalling
During the past decade considerable evidence has accumulated demonstrating the exposures of cells of the immune system to relatively weak extremely-low-frequency (ELF) electromagnetic fields (< 300 Hz) can elicit cellular changes which might be relevant to in-vivo immune activity. However, knowledge about the underlying biological mechanisms by which weak fields induce cellular changes is still very limited. It is generally believed that the cell membrane and Ca{sup 2+} regulated activity is involved in bioactive ELF field-coupling to living systems. This article begins with a short review of the current state of knowledge concerning the effects of nonthermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells, and then closely examines new results which suggest a role for Ca{sup 2+} in the induction of these cellular field effects. Based on these findings it is proposed that membrane-mediated Ca{sup 2+} signalling processes are involved in the mediation of field effects on the immune system. 64 refs., 2 tabs.
ELECTROMAGNETIC FIELD MEASUREMENT OF FUNDAMENTAL AND HIGHER-ORDER MODES FOR 7-CELL CAVITY OF PETRA-II
The booster synchrotron for NSLS-II will include a 7-cell PETRA cavity, which was manufactured for the PETRA-II project at DESY. The cavity fundamental frequency operates at 500 MHz. In order to verify the impedances of the fundamental and higher-order modes (HOM), which were calculated by computer code, we measured the magnitude of the electromagnetic field of the fundamental acceleration mode and HOM using the bead-pull method. To keep the cavity body temperature constant, we used a chiller system to supply cooling water at 20 degrees C. The bead-pull measurement was automated with a computer. We encountered some issues during the measurement process due to the difficulty in measuring the electromagnetic field magnitude in a multi-cell cavity. We describe the method and apparatus for the field measurement, and the obtained results.
Electromagnetic field measurements on a mm-wave linear accelerator
Field strength measurements for the determination of the R/Q of a mm-wave, 50-MeV electron linear accelerator using perturbational techniques are described. The perturbation is achieved using optical fibers coated with a thin metallic film to form a hollow cylinder. The perturbational form factors for such a geometry are approximated using several simple analytical expressions which are compared to a finite difference calculation as well as experimental results on a known cavity.
Electromagnetic Fields Due to a Loop Current in a CasedBorehole Surrounded by Uniform Whole Space
Precise evaluation of electromagnetic (EM) response in steel-cased borehole is an essential first step towards developing techniques for casing parameter evaluation, which would ultimately help evaluating the formation response. In this report we demonstrate a numerical scheme for accurately computing EM responses in cased borehole environment. For improved numerical accuracy we use explicit representations of the electromagnetic spectra inside the borehole, in the casing, and in the formation. Instead of conventional Hankel transform, FFT is used to improve the numerical accuracy. The FFT approach allows us to compute fields at positions very close to the source loop, including the center of the transmitter loop.
Electromagnetic fields in an axial symmetric waveguide with variable cross section
A new class of separable variables is found which allows one to find an approximate analytical solution of the Maxwell equations for axial symmetric waveguides with slow (but not necessarily small) varying boundary surfaces. An example of the solution is given. Possible applications and limitations of this approach are discussed.
Electromagnetic fields in axial symmetric waveguides with variable cross section
A new class of separable variables is found which allows one to find an approximate analytical solution of the Maxwell equations for axial symmetric waveguides with slow (but not necessarily small) varying boundary surfaces. An example of the solution is given. Possible applications and limitations of this approach are discussed. 6 refs., 10 figs.
Electromagnetic fields in cased borehole
Borehole electromagnetic (EM) measurements, using fiberglass-cased boreholes, have proven useful in oil field reservoir characterization and process monitoring (Wilt et al., 1995). It has been presumed that these measurements would be impossible in steel-cased wells due to the very large EM attenuation and phase shifts. Recent laboratory and field studies have indicated that detection of EM signals through steel casing should be possible at low frequencies, and that these data provide a reasonable conductivity image at a useful scale. Thus, we see an increased application of this technique to mature oilfields, and an immediate extension to geothermal industry as well. Along with the field experiments numerical model studies have been carried out for analyzing the effect of steel casing to the EM fields. The model used to be an infinitely long uniform casing embedded in a homogeneous whole space. Nevertheless, the results indicated that the formation signal could be accurately recovered if the casing characteristics were independently known (Becker et al., 1998; Lee el al., 1998). Real steel-cased wells are much more complex than the simple laboratory models used in work to date. The purpose of this study is to develop efficient numerical methods for analyzing EM fields in realistic settings, and to evaluate the potential application of EM technologies to cross-borehole and single-hole environment for reservoir characterization and monitoring.
An Electromagnetic Finite Difference Time Domain Analog Treatment of Small Signal Acoustic Interactions
Hyperbolic partial differential equations encompass an extremely important set of physical phenomena including electromagnetics and acoustics. Small amplitude acoustic interactions behave much the same as electromagnetic interactions for longitudinal acoustic waves because of the similar nature of the governing hyperbolic equations. Differences appear when transverse acoustic waves are considered, nonetheless the strong analogy between the acoustic and electromagnetic phenomena prompted the development of a Finite Difference Time Domain (FDTD) acoustic analog to the existing electromagnetic FDTD technique. The advantage of an acoustic FDTD (AFDTD) code are as follows: (1) Boundary condition-free treatment of the acoustic scatterer -- only the intrinsic properties of the scatterer`s material are needed, no shell treatment or other set of special equations describing the macroscopic behavior of a sheet of material or a junction, etc. are required; this allows completely general geometries and materials in the model. (2) Advanced outer radiation boundary condition analogs -- in the electromagnetics arena, highly absorbing outer radiation boundary conditions have been developed that can be applied with little modification to the acoustics arena with equal success. (3) A suite of preexisting capabilities related to electromagnetic modeling -- this includes automated model generation and interaction visualization as its most important components and is best exemplified by the capabilities of the LLNL generated TSAR electromagnetic FDTD code.
Electromagnetic Flowmeter
The following report documents progress the development of an electromagnetic flowmeter that measures the flow of half alloy, covering the period for March 1 to November 30, 1947.
An Electromagnetic Flowmeter for Rocket Research
"A method of measuring instantaneous flow rates of liquid propellants for rocket research is presented. The instrument investigated utilizes the principle of electromagnetic induction. An electromagnetic flowmeter was built, investigated, and satisfactorily placed in service to measure the rate of flow of an oxidant into a rocket" (p. 1).
Electromagnetic Fluctuations during Fast Reconnection in a Laboratory Plasma
Clear evidence for a positive correlation is established between the magnitude of magnetic fluctuations in the lower-hybrid frequency range and enhancement of reconnection rates in a well-controlled laboratory plasma. The fluctuations belong to the right-hand polarized whistler wave branch, propagating obliquely to the reconnecting magnetic field, with a phase velocity comparable to the relative drift velocity between electrons and ions. The short coherence length and large variation along the propagation direction indicate their strongly nonlinear nature in three dimensions.
Electromagnetic form factors of hadrons
A vector meson dominance model of the electromagnetic form factors of hadrons is developed which is based on the use of unstable particle propagators. Least-square fits are made to the proton, neutron, pion and kaon form factor data in both the space and time-like regions. A good fit to the low-energy nucleon form factor data is obtained using only rho, $omega$, and phi dominance, and leads to a determination of the vector meson resonance parameters in good agreement with experiment. The nucleon-vector meson coupling constants obey simple sum rules indicating that there exists no hard core contribution to the form factors within theoretical uncertainties. The prediction for the electromagnetic radii of the proton is in reasonable agreement with recent experiments. The pion and kaon charge form factors as deduced from the nucleon form factors assuming vector meson universality are compared to the data. The pion form factor agrees with the data in both the space and time-like regions. The pion charge radius is in agreement with the recent Dubna result, but the isovector P-wave pion-pion phase shift calculated from the theory disagrees with experiment. A possible contribution to the form factors from a heavy rho meson is also evaluated. (auth)
Electromagnetic gauge measurements of shock initiating PBX9501 and PBX9502 explosives
The authors have used an embedded electromagnetic particle velocity gauge technique to measure the shock initiation behavior in PBX9501 and PBX9502 explosives. Experiments have been conducted in which up to twelve separate measurements have been made in a single experiment which detail the growth from an input shock to a detonation. In addition, another gauge element called a shock tracker has been used to monitor the progress of the shock front as a function of time, thus providing a position-time trajectory of the wave front as it moves through the explosive sample. This provides similar data to that obtained in a traditional wedge test and is used to determine the position and time that the wave attains detonation. Data on both explosives show evidence of heterogeneous initiation (growth in the front) and homogeneous initiation (growth behind the front) with the PBX9502 showing more Heterogeneous behavior and the PBX 9501 showing more homogeneous behavior.
Electromagnetic Gyrokinetic Simulations
A new electromagnetic kinetic electron {delta} particle simulation model has been demonstrated to work well at large values of plasma {beta} times the ion-to-electron mass ratio. The simulation is three-dimensional using toroidal flux-tube geometry and includes electron-ion collisions. The model shows accurate shear Alfven wave damping and microtearing physics. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary, even though the linear behavior of the zonal flow is not significantly affected by kinetic electrons. zonal fields are found to be very weak, consistent with theoretical predictions for {beta} below the kinetic ballooning limit. Detailed spectral analysis of the turbulence data is presented in the various limits.
Electromagnetic Heating Methods for Heavy Oil Reservoirs
The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations.
An electromagnetic helical undulator for polarized x-rays
Linearly and circularly polarized x-rays have been very successfully applied to the study of the properties of materials. Many applications can benefit from the availability of energy-turnable, high-brilliance x-ray beams with adjustable polarization properties. A helical undulator that can generate beams of variable (linear to circular) polarization has been designed and built by the Budker Institute of Nuclear Physics and the Advanced Photon Source. The first harmonic of this 12.8-cm-period device will cover the energy range from 0.4 keV to 3.5 keV. An important feature of this fully electromagnetic device is that it will allow one to generate 100% horizontally (K{sub x}=O)or vertically (K{sub y}=O) plane-polarized radiation, which will enable many experiments otherwise not technically feasible. With symmetric deflection parameters (K{sub x}=K{sub y}), the on-axis radiation will be circularly polarized, with a user-selectable handedness. The polarization can be changed at rates up to 10 Hz.
Electromagnetic hysteretic response calculation for superconductors in demagnetizing geometries
A method has been outlined for calculating the flux front profile for a superconducting sample in either a uniform or nonuniform applied magnetic field possessing azimuthal symmetry. This technique relies upon finding a surface with zero vector potential. This surface is determined by simple integration of its derivative with respect to the external field, found by resolving a linear integral equation of the first kind. Measurement induced voltages and the entire hysteresis loop response can be found by extension of the ZFC magnetization response with increasing external field. Other experimentally measured quantities relating to the critical state can be calculated directly from the hysteresis loop if the time dependence of the external field is known. The technique shown in this report for solving the critical state model in the Bean approximation can be extended to field-dependent critical currents and other azimuthally symmetrical external fields. This work is presently in progress.
Electromagnetic imaging of a fuel oil spill at Sandia/CA
The multifrequency, multisource integral wave migration method commonly used in the analysis of seismic data is extended to electromagnetic (EM) data within the audio frequency range. The method is applied to the secondary magnetic fields produced by a borehole, vertical electric source (VES). The integral wave-migration method is a numerical reconstruction procedure utilizing Green`s theorem where the fields are migrated (extrapolated) from the measuring aperture into the interior of the earth. To form the image, the approach used here is to Fourier transform the constructed image from frequency domain to time domain and set time equal to zero. The image is formed when the in-phase part (real part) is a maximum or the out-of-phase (imaginary part) is a minimum; ie., the EM wave is phase coherent at its origination. In the application here, the secondary magnetic fields are treated as scattered fields. To determine the conductivity, the measured data migrated to a pixel location are equated to calculated data migrated to the same pixel. The conductivity is determined from solving a Fredholm integral equation of the first kind by solving a system of linear algebraic equations. The multifrequency, multisource integral wave-migration method is applied to calculated model data and to actual field data acquired to map a diesel fuel oil spill. For the application discussed here, a two dimensional resistivity slice is calculated from the solution to the Fredholm integral equation. The resistivity image of the fuel oil agrees with the known location.
Electromagnetic Imaging of C02 Sequestration at an Enhanced Oil Recovery Site
Lawrence Livermore National Laboratory (LLNL) is currently involved in a long term study using time-lapse multiple frequency electromagnetic (EM) characterization at a waterflood enhanced oil recovery (EOR) site in California operated by Chevron Heavy Oil Division in Lost Hills, California. The petroleum industry's interest and the successful imaging results from this project suggest that this technique be extended to monitor CO{sub 2} sequestration at an EOR site also operated by Chevron. The impetus for this study is to develop the ability to image subsurface injected CO{sub 2} during EOR processes while simultaneously discriminating between pre-existing petroleum and water deposits. The goals of this study are to combine laboratory and field methods to image a pilot CO{sub 2} sequestration EOR site using the cross-borehole EM technique, improve the inversion process in CO{sub 2} studies by coupling results with petrophysical laboratory measurements, and focus on new gas interpretation techniques. In this study we primarily focus on how joint field and laboratory results can provide information on subsurface CO{sub 2} detection, CO{sub 2} migration tracking, and displacement of petroleum and water over time. This study directly addresses national energy issues in two ways: (1) the development of field and laboratory techniques to improve in-situ analysis of oil and gas enhanced recovery operations and, (2) this research provides a tool for in-situ analysis of CO{sub 2} sequestration, an international technical issue of growing importance.
Electromagnetic Imaging of CO2 Sequestration at an Enhanced-Oil-Recovery Site
No Description Available.
Electromagnetic Imaging of CO2 Sequestration at an Enhanced Oil Recovery Site
Lawrence Livermore National Laboratory (LLNL) is currently involved in a long term study using time-lapse multiple frequency electromagnetic (EM) characterization at a waterflood enhanced oil recovery (EOR) site in California operated by Chevron Heavy Oil Division in Lost Hills, California (Figure 1). The petroleum industry's interest and the successful imaging results from this project suggest that this technique be extended to monitor CO{sub 2} sequestration at an EOR site also operated by Chevron. The impetus for this study is to develop the ability to image subsurface injected CO{sub 2} during EOR processes while simultaneously discriminating between pre-existing petroleum and water deposits. The goals of this study are to combine laboratory and field methods to image a pilot CO{sub 2} sequestration EOR site using the cross-borehole EM technique, improve the inversion process in CO{sub 2} studies by coupling results with petrophysical laboratory measurements, and focus on new gas interpretation techniques. In this study we primarily focus on how joint field and laboratory results can provide information on subsurface CO{sub 2} detection, CO{sub 2} migration tracking, and displacement of petroleum and water over time. This study directly addresses national energy issues in two ways: (1) the development of field and laboratory techniques to improve in-situ analysis of oil and gas enhanced recovery operations and, (2) this research provides a tool for in-situ analysis of CO{sub 2} sequestration, an international technical issue of growing importance.
Electromagnetic Imaging of CO2 Sequestration at an Enhanced-Oil-Recovery Site
The two year LDRD-ER-089 project Electromagnetic Imaging of CO{sub 2} Sequestration at an Enhanced-Oil-Recovery Site used a dual track approach to imaging and interpreting the effectiveness and migration of CO2 injection at an enhanced oil recovery site. Both field data and laboratory data were used together to aid in the interpretation and understanding of CO{sub 2} flow in a heavily fracture enhanced oil recovery site. In particular, project highlights include; {lg_bullet} The development of a low-noise digital field system to measure the EM induction response to CO{sub 2} in a variety of field conditions. Central to this system is a low-noise induction receiver antenna that can measure the low-energy response of the CO{sub 2}. This system has consistently measured a shallow pseudo-miscible CO{sub 2} flood at source frequencies between 2.0 kHz and 10 kHz. In addition, the existing and added oil and brine in the formation have also been characterized. {lg_bullet} Comparisons of cross-well images with induction logs acquired before drilling suggest the EM induction resolution for CO2 imaging is equivalent with applications to waterflood imaging completed at LLNL. {lg_bullet} The development and use of laboratory equipment to conduct fluid and gas time-lapsed injection studies of core samples using fluids acquired in the field. Measurements of the resistivity during this injection process and the ability to make instantaneous measurements of the frequency response provide a unique dataset for interpretation. {lg_bullet} The development of an optimum finite difference grid spacing that allows for stable inversions at different frequencies. {lg_bullet} The use of time-lapse field images to show the change of electrical conductivity in the field scales to the laboratory results. Using this result, we can approximate an interpretation of field images based on the rate-of-change of the laboratory results. {lg_bullet} The application of Q-domain processing is not applicable at this site …
Electromagnetic imaging of dynamic brain activity
Neural activity in the brain produces weak dynamic electromagnetic fields that can be measured by an array of sensors. Using a spatio-temporal modeling framework, we have developed a new approach to localization of multiple neural sources. This approach is based on the MUSIC algorithm originally developed for estimating the direction of arrival of signals impinging on a sensor array. We present applications of this technique to magnetic field measurements of a phantom and of a human evoked somatosensory response. The results of the somatosensory localization are mapped onto the brain anatomy obtained from magnetic resonance images.
Electromagnetic imaging of dynamic brain activity
Neural activity in the brain produces weak dynamic electromagnetic fields that can be measured by an array of sensors. Using a spatio-temporal modeling framework, we have developed a new approach to localization of multiple neural sources. This approach is based on the MUSIC algorithm originally developed for estimating the direction of arrival of signals impinging on a sensor array. We present applications of this technique to magnetic field measurements of a phantom and of a human evoked somatosensory response. The results of the somatosensory localization are mapped onto the brain anatomy obtained from magnetic resonance images.
Electromagnetic Induction by a Tilted Magnetic Dipole in an Electrically Anisotropic Formation
No Description Available.
Electromagnetic Induction in a Fully 3D Anisotropic Earth
No Description Available.
An electromagnetic induction method for underground target detection and characterization
An improved capability for subsurface structure detection is needed to support military and nonproliferation requirements for inspection and for surveillance of activities of threatening nations. As part of the DOE/NN-20 program to apply geophysical methods to detect and characterize underground facilities, Sandia National Laboratories (SNL) initiated an electromagnetic induction (EMI) project to evaluate low frequency electromagnetic (EM) techniques for subsurface structure detection. Low frequency, in this case, extended from kilohertz to hundreds of kilohertz. An EMI survey procedure had already been developed for borehole imaging of coal seams and had successfully been applied in a surface mode to detect a drug smuggling tunnel. The SNL project has focused on building upon the success of that procedure and applying it to surface and low altitude airborne platforms. Part of SNL`s work has focused on improving that technology through improved hardware and data processing. The improved hardware development has been performed utilizing Laboratory Directed Research and Development (LDRD) funding. In addition, SNL`s effort focused on: (1) improvements in modeling of the basic geophysics of the illuminating electromagnetic field and its coupling to the underground target (partially funded using LDRD funds) and (2) development of techniques for phase-based and multi-frequency processing and spatial processing to support subsurface target detection and characterization. The products of this project are: (1) an evaluation of an improved EM gradiometer, (2) an improved gradiometer concept for possible future development, (3) an improved modeling capability, (4) demonstration of an EM wave migration method for target recognition, and a demonstration that the technology is capable of detecting targets to depths exceeding 25 meters.
Electromagnetic induction moisture measurement system acceptance test plan
The purpose of this acceptance test plan (ATP) is to verify that the mechanical, electrical and software features of the ElectroMagnetic Induction (EMI) probe are operating as designed,and that the unit is ready for field service. The accepted EMI and Surface Moisture Measurement Systems (SMMS) will be used primarily in support of Tank Waste Remediation System (TWRS) Safety Programs for moisture measurement of organic and ferrocyanide watch list tanks.
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