Volpe, F. A.; Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Olofsson, K. E. J.
2013-04-01
A new non-disruptive error field (EF) assessment technique not restricted to low density and thus low beta was demonstrated at the EXTRAP-T2R reversed field pinch. Stable and marginally stable external kink modes of toroidal mode number n = 10 and n = 8, respectively, were generated, and their rotation sustained, by means of rotating magnetic perturbations of the same n. Due to finite EFs, and in spite of the applied perturbations rotating uniformly and having constant amplitude, the kink modes were observed to rotate non-uniformly and be modulated in amplitude. This behaviour was used to precisely infer the amplitude and approximately estimate the toroidal phase of the EF. A subsequent scan permitted to optimize the toroidal phase. The technique was tested against deliberately applied as well as intrinsic EFs of n = 8 and 10. Corrections equal and opposite to the estimated error fields were applied. The efficacy of the error compensation was indicated by the increased discharge duration and more uniform mode rotation in response to a uniformly rotating perturbation. The results are in good agreement with theory, and the extension to lower n, to tearing modes and to tokamaks, including ITER, is discussed.
Energy Technology Data Exchange (ETDEWEB)
Elliott, C.J.; McVey, B. (Los Alamos National Lab., NM (USA)); Quimby, D.C. (Spectra Technology, Inc., Bellevue, WA (USA))
1990-01-01
The level of field errors in an FEL is an important determinant of its performance. We have computed 3D performance of a large laser subsystem subjected to field errors of various types. These calculations have been guided by simple models such as SWOOP. The technique of choice is utilization of the FELEX free electron laser code that now possesses extensive engineering capabilities. Modeling includes the ability to establish tolerances of various types: fast and slow scale field bowing, field error level, beam position monitor error level, gap errors, defocusing errors, energy slew, displacement and pointing errors. Many effects of these errors on relative gain and relative power extraction are displayed and are the essential elements of determining an error budget. The random errors also depend on the particular random number seed used in the calculation. The simultaneous display of the performance versus error level of cases with multiple seeds illustrates the variations attributable to stochasticity of this model. All these errors are evaluated numerically for comprehensive engineering of the system. In particular, gap errors are found to place requirements beyond mechanical tolerances of {plus minus}25{mu}m, and amelioration of these may occur by a procedure utilizing direct measurement of the magnetic fields at assembly time. 4 refs., 12 figs.
Error field considerations for BPX
International Nuclear Information System (INIS)
LaHaye, R.J.
1992-01-01
Irregularities in the position of poloidal and/or toroidal field coils in tokamaks produce resonant toroidal asymmetries in the vacuum magnetic fields. Otherwise stable tokamak discharges become non-linearly unstable to disruptive locked modes when subjected to low level error fields. Because of the field errors, magnetic islands are produced which would not otherwise occur in tearing mode table configurations; a concomitant reduction of the total confinement can result. Poloidal and toroidal asymmetries arise in the heat flux to the divertor target. In this paper, the field errors from perturbed BPX coils are used in a field line tracing code of the BPX equilibrium to study these deleterious effects. Limits on coil irregularities for device design and fabrication are computed along with possible correcting coils for reducing such field errors
Quantized fields in external field. Pt. 2
International Nuclear Information System (INIS)
Bellissard, J.
1976-01-01
The case of a charged scalar field is considered first. The existence of the corresponding Green's functions is proved. For weak fields, as well as pure electric or scalar external fields, the Bogoliubov S-operator is shown to be unitary, covariant, causal up-to-a-phase. These results are generalised to a class of higher spin quantized fields, 'nicely' coupled to external fields, which includes the Dirac theory, and in the case of minimal and magnetic dipole coupling, the spin one Petiau-Duffin-Kemmer theory. (orig.) [de
Field errors in hybrid insertion devices
International Nuclear Information System (INIS)
Schlueter, R.D.
1995-02-01
Hybrid magnet theory as applied to the error analyses used in the design of Advanced Light Source (ALS) insertion devices is reviewed. Sources of field errors in hybrid insertion devices are discussed
Field errors in hybrid insertion devices
Energy Technology Data Exchange (ETDEWEB)
Schlueter, R.D. [Lawrence Berkeley Lab., CA (United States)
1995-02-01
Hybrid magnet theory as applied to the error analyses used in the design of Advanced Light Source (ALS) insertion devices is reviewed. Sources of field errors in hybrid insertion devices are discussed.
Resistive wall modes and error field amplification
International Nuclear Information System (INIS)
Boozer, Allen H.
2003-01-01
Resistive wall modes and the rapid damping of plasma rotation by the amplification of magnetic field errors are related physical phenomena that affect the performance of the advanced tokamak and spherical torus plasma confinement devices. Elements of our understanding of these phenomena and the code that is used to design the major experimental facilities are based on the electrical circuit representation of the response of the plasma to perturbations. Although the circuit representation of the plasma may seem heuristic, this representation can be rigorously obtained using Maxwell's equations and linearity for plasmas that evolve on a disparate time scale from that of external currents. These and related results are derived. In addition methods are given for finding the plasma information that the circuit representation requires using post-processors for codes that calculate perturbed plasma equilibria
Relaxed plasmas in external magnetic fields
International Nuclear Information System (INIS)
Spies, G.O.; Li, J.
1991-08-01
The well-known theory of relaxed plasmas (Taylor states) is extended to external magnetic fields whose field lines intersect the conducting toroidal boundary. Application to an axially symmetric, large-aspect-ratio torus with circular cross section shows that the maximum pinch ratio, and hence the phenomenon of current saturation, is independent of the external field. The relaxed state is explicitly given for an external octupole field. In this case, field reversal is inhibited near parts of the boundary if the octupole generates magnetic x-points within the plasma. (orig.)
Influence of error fields on the plasma confining field and the plasma confinement in tokamak
International Nuclear Information System (INIS)
Matsuda, Shinzaburo
1977-05-01
Influence of error fields on the plasma confining field and the plasma confinement is treated in the standpoint of design. In the initial breakdown phase before formation of the closed magnetic surfaces, the vertical field properly applied is the most important. Once the magnetic surfaces are formed, the non-axisymmetric error field is important. Effect of the shell gap associated with iron core and with pulsed vertical coils is thus studied. The formation of magnetic islands due to the external non-axisymmetric error field is studied with a simple model. A method of suppressing the islands by choosing the minor periodicity is proposed. (auth.)
Magnetic field errors tolerances of Nuclotron booster
Butenko, Andrey; Kazinova, Olha; Kostromin, Sergey; Mikhaylov, Vladimir; Tuzikov, Alexey; Khodzhibagiyan, Hamlet
2018-04-01
Generation of magnetic field in units of booster synchrotron for the NICA project is one of the most important conditions for getting the required parameters and qualitative accelerator operation. Research of linear and nonlinear dynamics of ion beam 197Au31+ in the booster have carried out with MADX program. Analytical estimation of magnetic field errors tolerance and numerical computation of dynamic aperture of booster DFO-magnetic lattice are presented. Closed orbit distortion with random errors of magnetic fields and errors in layout of booster units was evaluated.
Field errors in superconducting magnets
International Nuclear Information System (INIS)
Barton, M.Q.
1982-01-01
The mission of this workshop is a discussion of the techniques for tracking particles through arbitrary accelerator field configurations to look for dynamical effects that are suggested by various theoretical models but are not amenable to detailed analysis. A major motivation for this type of study is that many of our accelerator projects are based on the use of superconducting magnets which have field imperfections that are larger and of a more complex nature than those of conventional magnets. Questions such as resonances, uncorrectable closed orbit effects, coupling between planes, and diffusion mechanisms all assume new importance. Since, simultaneously, we are trying to do sophisticated beam manipulations such as stacking, high current accelerator, long life storage, and low loss extraction, we clearly need efficient and accurate tracking programs to proceed with confidence
Plasmon instability under four external fields
International Nuclear Information System (INIS)
Pereira, R.B.; Fonseca, A.L.A.; Nunes, O.A.C.
1998-01-01
The plasmon instability in a laboratory produced plasma in the presence of four external fields, namely two laser fields, one strong magnetic field and one static electric field, is discussed. The method of unitary transformations is used to transform the problem of electron motion under the four external fields to that of an electron in the presence only of crossed electric and magnetic fields. A kinetic equation for the plasmon population is derived from which the damping (amplification) rate is calculated. We found that the joint action of the four fields results in a relatively larger amplification rate for some values of the static electric field in contrast to the case where no electric field is present. It was also found that the plasmon growth rate favors plasmon wave vectors in an extremely narrow band i.e., the plasmon instability in four external fields is a very selective mechanism for plasmon excitation. (author)
Atomic excitation and recombination in external fields
International Nuclear Information System (INIS)
Nayfeh, M.H.; Clark, C.W.
1985-01-01
This volume offers a timely look at Rydberg states of atoms in external fields and dielectronic recombination. Each topic provides authoritative coverage, presents a fresh account of a flourishing field of current atomic physics and introduces new opportunities for discovery and development. Topics considered include electron-atom scattering in external fields; observations of regular and irregular motion as exemplified by the quadratic zeeman effect and other systems; Rydberg atoms in external fields and the Coulomb geometry; crossed-field effects in the absorption spectrum of lithium in a magnetic field; precise studies of static electric field ionization; widths and shapes of stark resonances in sodium above the saddle point; studies of electric field effects and barium autoionizing resonances; autoionization and dielectronic recombination in plasma electric microfields; dielectronic recombination measurements on multicharged ions; merged beam studies of dielectronic recombination; Rydberg atoms and dielectronic recombination in astrophysics; and observations on dielectronic recombination
Quantization in presence of external soliton fields
International Nuclear Information System (INIS)
Grosse, H.; Karner, G.
1986-01-01
Quantization of a fermi field interacting with an external soliton protential is considered. Classes of interactions leading to unitarily equivalent representations of the canonical anticommutation relations are determined. Soliton-like potentials compared to trivial ones yield inequivalent representations. (Author)
Analysis of field errors in existing undulators
International Nuclear Information System (INIS)
Kincaid, B.M.
1990-01-01
The Advanced Light Source (ALS) and other third generation synchrotron light sources have been designed for optimum performance with undulator insertion devices. The performance requirements for these new undulators are explored, with emphasis on the effects of errors on source spectral brightness. Analysis of magnetic field data for several existing hybrid undulators is presented, decomposing errors into systematic and random components. An attempts is made to identify the sources of these errors, and recommendations are made for designing future insertion devices. 12 refs., 16 figs
Charged particles in external electromagnetic fields
International Nuclear Information System (INIS)
Giovannini, N.P.D.
1976-01-01
The present study contains a general theoretical group analysis of the problem of a charged massive particle moving in an (arbitrary) classical external electromagnetic field. This analysis is essentially based on the space-time symmetry properties of e.m. fields and e.m. field equations, as well as the fact that the considered equations of motion depend on the field via a potential
Coherent polarization driven by external electromagnetic fields
International Nuclear Information System (INIS)
Apostol, M.; Ganciu, M.
2010-01-01
The coherent interaction of the electromagnetic radiation with an ensemble of polarizable, identical particles with two energy levels is investigated in the presence of external electromagnetic fields. The coupled non-linear equations of motion are solved in the stationary regime and in the limit of small coupling constants. It is shown that an external electromagnetic field may induce a macroscopic occupation of both the energy levels of the particles and the corresponding photon states, governed by a long-range order of the quantum phases of the internal motion (polarization) of the particles. A lasing effect is thereby obtained, controlled by the external field. Its main characteristics are estimated for typical atomic matter and atomic nuclei. For atomic matter the effect may be considerable (for usual external fields), while for atomic nuclei the effect is extremely small (practically insignificant), due to the great disparity in the coupling constants. In the absence of the external field, the solution, which is non-analytic in the coupling constant, corresponds to a second-order phase transition (super-radiance), which was previously investigated.
Crystal growth under external electric fields
International Nuclear Information System (INIS)
Uda, Satoshi; Koizumi, Haruhiko; Nozawa, Jun; Fujiwara, Kozo
2014-01-01
This is a review article concerning the crystal growth under external electric fields that has been studied in our lab for the past 10 years. An external field is applied electrostatically either through an electrically insulating phase or a direct injection of an electric current to the solid-interface-liquid. The former changes the chemical potential of both solid and liquid and controls the phase relationship while the latter modifies the transport and partitioning of ionic solutes in the oxide melt during crystallization and changes the solute distribution in the crystal
Crystal growth under external electric fields
Energy Technology Data Exchange (ETDEWEB)
Uda, Satoshi; Koizumi, Haruhiko; Nozawa, Jun; Fujiwara, Kozo [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)
2014-10-06
This is a review article concerning the crystal growth under external electric fields that has been studied in our lab for the past 10 years. An external field is applied electrostatically either through an electrically insulating phase or a direct injection of an electric current to the solid-interface-liquid. The former changes the chemical potential of both solid and liquid and controls the phase relationship while the latter modifies the transport and partitioning of ionic solutes in the oxide melt during crystallization and changes the solute distribution in the crystal.
Polaron scattering by an external field
International Nuclear Information System (INIS)
Kochetov, E.A.
1980-01-01
The problem of polaron scattering by an external field is studied. The problem is solved using the stationary scattering theory formalism based on two operators: the G Green function operator and the T scattering operator. The dependence of the scattering amplitude on the quasi particle structure is studied. The variation approach is used for estimation of the ground energy level
Spherical tokamak without external toroidal fields
International Nuclear Information System (INIS)
Kaw, P.K.; Avinash, K.; Srinivasan, R.
2001-01-01
A spherical tokamak design without external toroidal field coils is proposed. The tokamak is surrounded by a spheromak shell carrying requisite force free currents to produce the toroidal field in the core. Such equilibria are constructed and it is indicated that these equilibria are likely to have robust ideal and resistive stability. The advantage of this scheme in terms of a reduced ohmic dissipation is pointed out. (author)
Error field generation of solenoid magnets
International Nuclear Information System (INIS)
Saunders, J.L.
1982-01-01
Many applications for large solenoids and solenoidal arrays depend on the high precision of the axial field profile. In cases where requirements of ΔB/B for nonaxial fields are on the order of 10 -4 , the actual winding techniques of the solenoid need to be considered. Whereas an ideal solenoid consisting of current loops would generate no radial fields along the axis, in reality, the actual current-carrying conductors must follow spiral or helical paths. A straightforward method for determining the radial error fields generated by coils wound with actual techniques employed in magnet fabrication has been developed. The method devised uses a computer code which models a magnet by sending a single, current-carrying filament along the same path taken by the conductor during coil winding. Helical and spiral paths are simulated using small, straight-line current segments. This technique, whose results are presented in this paper, was used to predict radial field errors for the Elmo Bumpy Torus-Proof of Principle magnet. These results include effects due to various winding methods, not only spiral/helical and layer-to-layer transitions, but also the effects caused by worst-case tolerance conditions both from the conductor and the winding form (bobbin). Contributions made by extraneous circuitry (e.g., overhead buswork and incoming leads) are also mentioned
Quantized fields in interaction with external fields. Pt. 1
International Nuclear Information System (INIS)
Bellissard, J.
1975-01-01
We consider a massive, charged, scalar quantized field interacting with an external classical field. Guided by renormalized perturbation theory we show that whenever the integral equations defining the Feynman or retarded or advanced interaction kernel possess non perturbative solutions, there exists an S-operator which satisfies, up to a phase, the axioms of Bogoliubov, and is given for small external fields by a power series which converges on coherent states. Furthermore this construction is shown to be equivalent to the one based on the Yang-Kaellen-Feldman equation. This is a consequence of the relations between chronological and retarded Green's functions which are described in detail. (orig.) [de
Magnetic response to applied electrostatic field in external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Adorno, T.C. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); University of Florida, Department of Physics, Gainesville, FL (United States); Gitman, D.M. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Shabad, A.E. [P. N. Lebedev Physics Institute, Moscow (Russian Federation)
2014-04-15
We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to the simple example of a spherically symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space; the pattern of the lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics. (orig.)
Locked modes and magnetic field errors in MST
International Nuclear Information System (INIS)
Almagri, A.F.; Assadi, S.; Prager, S.C.; Sarff, J.S.; Kerst, D.W.
1992-06-01
In the MST reversed field pinch magnetic oscillations become stationary (locked) in the lab frame as a result of a process involving interactions between the modes, sawteeth, and field errors. Several helical modes become phase locked to each other to form a rotating localized disturbance, the disturbance locks to an impulsive field error generated at a sawtooth crash, the error fields grow monotonically after locking (perhaps due to an unstable interaction between the modes and field error), and over the tens of milliseconds of growth confinement degrades and the discharge eventually terminates. Field error control has been partially successful in eliminating locking
Field errors in the RFX magnetic field configuration
International Nuclear Information System (INIS)
Bellina, F.; Campostrini, P.P.; Chitarin, G.; Fauri, M.; Zaccaria, P.L.
1987-01-01
Several factors can jeopardize the desired field configuration in the plasma region of a toroidal machine, namely: the wrong positioning of the coil conductors; the displacement of the coils due to the deflection of the mechanical structure; the currents in the busbars feeding the coils; the ferromagnetic materials around the machine; and the eddy currents in any conducting loop in the neighbourhood of the machine. This paper describes the various methods used for evaluating the effects of each item listed above and the technical solutions which have been adopted, case by case, in order to comply with the requirements on the field errors
Spinning relativistic particles in external fields
International Nuclear Information System (INIS)
Pomeranskii, Andrei A; Sen'kov, Roman A; Khriplovich, Iosif B
2000-01-01
The motion of spinning relativistic particles in external electromagnetic and gravitational fields is considered. The self-consistent equations of motion are built with the noncovariant description of spin and with the usual, 'naive' definition of the coordinate of a relativistic particle. A simple derivation of the gravitational interaction of first order in spin is presented for a relativistic particle. The approach developed allows one to consider effects of higher order in spin. Concrete calculations are performed for the second order. The gravimagnetic moment is discussed, a special spin effect in general relativity. We also consider the contributions of the spin interactions of first and second order to the gravitational radiation of compact binary stars. (from the current literature)
Error Field Correction in DIII-D Ohmic Plasmas With Either Handedness
International Nuclear Information System (INIS)
Park, Jong-Kyu; Schaffer, Michael J.; La Haye, Robert J.; Scoville, Timothy J.; Menard, Jonathan E.
2011-01-01
Error field correction results in DIII-D plasmas are presented in various configurations. In both left-handed and right-handed plasma configurations, where the intrinsic error fields become different due to the opposite helical twist (handedness) of the magnetic field, the optimal error correction currents and the toroidal phases of internal(I)-coils are empirically established. Applications of the Ideal Perturbed Equilibrium Code to these results demonstrate that the field component to be minimized is not the resonant component of the external field, but the total field including ideal plasma responses. Consistency between experiment and theory has been greatly improved along with the understanding of ideal plasma responses, but non-ideal plasma responses still need to be understood to achieve the reliable predictability in tokamak error field correction.
Non-linear instability of DIII-D to error fields
International Nuclear Information System (INIS)
La Haye, R.J.; Scoville, J.T.
1991-10-01
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 r21 /B T of about 1.7 x 10 -4 . The locked modes triggered by an external error field are aligned with the static error field and the plasma fluid rotation ceases as a result of the growth of the mode. The triggered locked modes are the precursors of the subsequent plasma disruption. The use of an ''n = 1 coil'' to partially cancel intrinsic errors, or to increase them, results in a significantly expanded, or reduced, stable operating parameter space. Precise error field measurements have allowed the design of an improved correction coil for DIII-D, the ''C-coil'', which could further cancel error fields and help to avoid disruptive locked modes. 6 refs., 4 figs
Thermodynamic properties of open noncritical string in external electromagnetic field
International Nuclear Information System (INIS)
Lichtzier, I.M.; Odintsov, S.D.; Bytsenko, A.A.
1991-01-01
We investigate the thermodynamics of open noncritical string (charged and neutral) in an external constant magnetic field. The free energy and Hagedorn temperature are calculated. It is shown that Hagedorn temperature is the same as in the absence of constant magnetic field. We present also the expressions for the free energy and Hagedorn temperature of the neutral open noncritical string in an external constant electromagnetic field. In this case Hagedorn temperature depends on the external electric field. (author)
Bifurcated states of the error-field-induced magnetic islands
International Nuclear Information System (INIS)
Zheng, L.-J.; Li, B.; Hazeltine, R.D.
2008-01-01
We find that the formation of the magnetic islands due to error fields shows bifurcation when neoclassical effects are included. The bifurcation, which follows from including bootstrap current terms in a description of island growth in the presence of error fields, provides a path to avoid the island-width pole in the classical description. The theory offers possible theoretical explanations for the recent DIII-D and JT-60 experimental observations concerning confinement deterioration with increasing error field
ERRORS AND FRAUD IN ACCOUNTING. THE ROLE OF EXTERNAL AUDIT IN FIGHTING CORRUPTION
Directory of Open Access Journals (Sweden)
Luminita Ionescu
2017-12-01
Full Text Available Accounting errors and fraud are common in most businesses, but there is a difference between fraud and misinterpretation of communication or accounting regulations. The role of management in preventing fraud becomes important in the last decades and the importance of auditing in curbing corruption is increasingly revealed. There is a strong connection between fraud and corruption, accelerated by electronic systems and modern platforms. The most recent developments tend to confirm that external auditing is curbing corruption, due to international accounting and auditing standards at national and regional levels. Thus, a better implementation of accounting standards and high quality of external control could prevent errors and fraud in accounting, and reduce corruption, as well. The aim of this paper is to present some particular aspects of errors and fraud in accounting, and how external audit could ensure accuracy and accountability in financial reporting.
Estimation of error fields from ferromagnetic parts in ITER
Energy Technology Data Exchange (ETDEWEB)
Oliva, A. Bonito [Fusion for Energy (Spain); Chiariello, A.G.; Formisano, A.; Martone, R. [Ass. EURATOM/ENEA/CREATE, Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy); Portone, A., E-mail: alfredo.portone@f4e.europa.eu [Fusion for Energy (Spain); Testoni, P. [Fusion for Energy (Spain)
2013-10-15
Highlights: ► The paper deals with error fields generated in ITER by magnetic masses. ► Magnetization state is computed from simplified FEM models. ► Closed form expressions adopted for the flux density of magnetized parts are given. ► Such expressions allow to simplify the estimation of the effect of iron pieces (or lack of) on error field. -- Abstract: Error fields in tokamaks are small departures from the exact axisymmetry of the ideal magnetic field configuration. Their reduction below a threshold value by the error field correction coils is essential since sufficiently large static error fields lead to discharge disruption. The error fields are originated not only by magnets fabrication and installation tolerances, by the joints and by the busbars, but also by the presence of ferromagnetic elements. It was shown that superconducting joints, feeders and busbars play a secondary effect; however in order to estimate of the importance of each possible error field source, rough evaluations can be very useful because it can provide an order of magnitude of the correspondent effect and, therefore, a ranking in the request for in depth analysis. The paper proposes a two steps procedure. The first step aims to get the approximate magnetization state of ferromagnetic parts; the second aims to estimate the full 3D error field over the whole volume using equivalent sources for magnetic masses and taking advantage from well assessed approximate closed form expressions, well suited for the far distance effects.
Leite, Maici Duarte; Marczal, Diego; Pimentel, Andrey Ricardo; Direne, Alexandre Ibrahim
2014-01-01
This paper presents the application of some concepts of Intelligent Tutoring Systems (ITS) to elaborate a conceptual framework that uses the remediation of errors with Multiple External Representations (MERs) in Learning Objects (LO). To this is demonstrated a development of LO for teaching the Pythagorean Theorem through this framework. This…
Mitigating Errors in External Respiratory Surrogate-Based Models of Tumor Position
International Nuclear Information System (INIS)
Malinowski, Kathleen T.; McAvoy, Thomas J.; George, Rohini; Dieterich, Sonja; D'Souza, Warren D.
2012-01-01
Purpose: To investigate the effect of tumor site, measurement precision, tumor–surrogate correlation, training data selection, model design, and interpatient and interfraction variations on the accuracy of external marker-based models of tumor position. Methods and Materials: Cyberknife Synchrony system log files comprising synchronously acquired positions of external markers and the tumor from 167 treatment fractions were analyzed. The accuracy of Synchrony, ordinary-least-squares regression, and partial-least-squares regression models for predicting the tumor position from the external markers was evaluated. The quantity and timing of the data used to build the predictive model were varied. The effects of tumor–surrogate correlation and the precision in both the tumor and the external surrogate position measurements were explored by adding noise to the data. Results: The tumor position prediction errors increased during the duration of a fraction. Increasing the training data quantities did not always lead to more accurate models. Adding uncorrelated noise to the external marker-based inputs degraded the tumor–surrogate correlation models by 16% for partial-least-squares and 57% for ordinary-least-squares. External marker and tumor position measurement errors led to tumor position prediction changes 0.3–3.6 times the magnitude of the measurement errors, varying widely with model algorithm. The tumor position prediction errors were significantly associated with the patient index but not with the fraction index or tumor site. Partial-least-squares was as accurate as Synchrony and more accurate than ordinary-least-squares. Conclusions: The accuracy of surrogate-based inferential models of tumor position was affected by all the investigated factors, except for the tumor site and fraction index.
Mitigating Errors in External Respiratory Surrogate-Based Models of Tumor Position
Energy Technology Data Exchange (ETDEWEB)
Malinowski, Kathleen T. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States); McAvoy, Thomas J. [Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States); Department of Chemical and Biomolecular Engineering and Institute of Systems Research, University of Maryland, College Park, MD (United States); George, Rohini [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Dieterich, Sonja [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); D' Souza, Warren D., E-mail: wdsou001@umaryland.edu [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States)
2012-04-01
Purpose: To investigate the effect of tumor site, measurement precision, tumor-surrogate correlation, training data selection, model design, and interpatient and interfraction variations on the accuracy of external marker-based models of tumor position. Methods and Materials: Cyberknife Synchrony system log files comprising synchronously acquired positions of external markers and the tumor from 167 treatment fractions were analyzed. The accuracy of Synchrony, ordinary-least-squares regression, and partial-least-squares regression models for predicting the tumor position from the external markers was evaluated. The quantity and timing of the data used to build the predictive model were varied. The effects of tumor-surrogate correlation and the precision in both the tumor and the external surrogate position measurements were explored by adding noise to the data. Results: The tumor position prediction errors increased during the duration of a fraction. Increasing the training data quantities did not always lead to more accurate models. Adding uncorrelated noise to the external marker-based inputs degraded the tumor-surrogate correlation models by 16% for partial-least-squares and 57% for ordinary-least-squares. External marker and tumor position measurement errors led to tumor position prediction changes 0.3-3.6 times the magnitude of the measurement errors, varying widely with model algorithm. The tumor position prediction errors were significantly associated with the patient index but not with the fraction index or tumor site. Partial-least-squares was as accurate as Synchrony and more accurate than ordinary-least-squares. Conclusions: The accuracy of surrogate-based inferential models of tumor position was affected by all the investigated factors, except for the tumor site and fraction index.
Quantum theory of relativistic charged particles in external fields
International Nuclear Information System (INIS)
Ruijsenaars, S.N.M.
1976-01-01
A study was made on external field theories in which the quantized field corresponds to relativistic elementary particles with non-zero rest mass. These particles are assumed to be charged, thus they have distinct antiparticles. The thesis consists of two parts. The first tries to accommodate the general features of theories of relativistic charged particles in external fields. Spin and dynamics in particular are not specified. In the second part, the results are applied to charged spin-1/2 and spin-0 particles, the dynamics of which are given by the Dirac resp. Klein-Gordon equation. The greater emphasis is on external fields which are rapidly decreasing, infinitely differentiable functions of space-time, but also considers time-independent fields. External fields, other than electromagnetic fields are also considered, e.g. scalar fields
The external field dependence of the BCS critical temperature
DEFF Research Database (Denmark)
Frank, Rupert L.; Hainzl, Christian; Seiringer, Robert
2016-01-01
We consider the Bardeen-Cooper-Schrieffer free energy functional for particles interacting via a two-body potential on a microscopic scale and in the presence of weak external fields varying on a macroscopic scale. We study the influence of the external fields on the critical temperature. We show...
The U(1) Higgs model in an external electromagnetic field
International Nuclear Information System (INIS)
Damgaard, P.H.; Heller, U.M.
1988-01-01
An external electromagnetic field is coupled to the lattice-regularized U(1) Higgs model. We study the phase diagram of this model by both analytical and numerical techniques for different values of the external field strength tensor. The results are compared with expectations based on the analogy with superconducting systems, as described by the phenomenological Ginzburg-Landau theory. (orig.)
Impact of error fields on equilibrium configurations in ITER
Energy Technology Data Exchange (ETDEWEB)
Barbato, Lucio [DIEI, Università di Cassino and Lazio Meridionale, Cassino (Italy); Formisano, Alessandro, E-mail: alessandro.formisano@unina2.it [Department of Industrial and Information Engineering, Seconda Univ. di Napoli, Aversa (Italy); Martone, Raffaele [Department of Industrial and Information Engineering, Seconda Univ. di Napoli, Aversa (Italy); Villone, Fabio [DIEI, Università di Cassino and Lazio Meridionale, Cassino (Italy)
2015-10-15
Highlights: • Error fields (EF) are discrepancies from nominal magnetic field, and may alter plasma behaviour. • They are due to, e.g., coils manufacturing and assembly errors. • EF impact in ITER equilibria is analyzed using numerical simulations. • A high accuracy 3D field computation module and a Grad-Shafranov solver are used. • Deformations size allow using a linearized model, and performing a sensitivity analysis. - Abstract: Discrepancies between design and actual magnetic field maps in tokamaks are unavoidable, and are associated to a number of causes, e.g. manufacturing and assembly tolerances on magnets, presence of feeders and joints, non-symmetric iron parts. Such error fields may drive plasma to loss of stability, and must be carefully controlled using suitable correction coils. Anyway, even when kept below safety threshold, error fields may alter the behavior of plasma. The present paper, using as example the error fields induced by tolerances in toroidal field coils, quantifies their effect on the plasma boundary shape in equilibrium configurations. In particular, a procedure able to compute the shape perturbations due to given deformations of the coils has been set up and used to carry out a thorough statistical analysis of the error field-shape perturbations relationship.
EDITORIAL: Colloidal dispersions in external fields Colloidal dispersions in external fields
Löwen, Hartmut
2012-11-01
Colloidal dispersions have long been proven as pivotal model systems for equilibrium phase transition such as crystallization, melting and liquid-gas phase transition. The last decades have revealed that this is also true for nonequilibrium phenomena. In fact, the fascinating possibility to track the individual trajectories of colloidal particles has greatly advanced our understanding of collective behaviour in classical many-body systems and has helped to reveal the underlying physical principles of glass transition, crystal nucleation, and interfacial dynamics (to name just a few typical nonequilibrium effects). External fields can be used to bring colloids out of equilibrium in a controlled way. Different kinds of external fields can be applied to colloidal dispersions, namely shear flow, electric, magnetic and laser-optical fields, and confinement. Typical research areas can be sketched with the by now traditional complexity diagram (figure 1). The complexity of the colloidal system itself as embodied in statistical degrees of freedom is shown on the x-axis while the complexity of the problem posed, namely bulk, an inhomogeneity in equilibrium, steady state nonequilibrium and full time-dependent nonequilibrium are shown on the y-axis. The different external fields which can be imposed are indicated by the different hatched areas. figure1 Figure 1. Diagram of complexity for colloidal dispersions in external fields: while the x-axis shows the complexity of the system, the y-axis shows the complexity of the problem. Regions which can be accessed by different kinds of external fields are indicated. The arrows indicate recent research directions. Active particles are also indicated with a special complexity of internal degrees of freedom [1]. This collection of papers reflects the scientific programme of the International Conference on Colloidal Dispersions in External Fields III (CODEF III) which took place in Bonn-Bad Godesberg from 20-23 March 2012. This was the
Quantum electrodynamics in strong external fields
International Nuclear Information System (INIS)
Mueller, B.; Rafelski, J.; Kirsch, J.
1981-05-01
We review the theoretical description of quantum electrodynamics in the presence of strong and supercritical fields. In particular, the process of the spontaneous vacuum decay accompanied by the observable positron emission in heavy ion collisions is described. Emphasis is put on the proper formulation of many-body aspects in the framework of quantum field theory. The extension of the theory to the description of Bose fields and many-body effects is presented, and the Klein paradox is resolved. Some implications of the theoretical methods developed here are presented concerning non-abelian gauge theories and the quark confinement puzzle. (orig.)
Field testing for cosmic ray soft errors in semiconductor memories
International Nuclear Information System (INIS)
O'Gorman, T.J.; Ross, J.M.; Taber, A.H.; Ziegler, J.F.; Muhlfeld, H.P.; Montrose, C.J.; Curtis, H.W.; Walsh, J.L.
1996-01-01
This paper presents a review of experiments performed by IBM to investigate the causes of soft errors in semiconductor memory chips under field test conditions. The effects of alpha-particles and cosmic rays are separated by comparing multiple measurements of the soft-error rate (SER) of samples of memory chips deep underground and at various altitudes above the earth. The results of case studies on four different memory chips show that cosmic rays are an important source of the ionizing radiation that causes soft errors. The results of field testing are used to confirm the accuracy of the modeling and the accelerated testing of chips
External magnetic field configurations for EXTRAP
International Nuclear Information System (INIS)
Bonnevier, B.
1982-08-01
The strongly inhomogeneous magnetic field for stabilization of a pinch in an Extrap configuration can be created in various ways. Some possibilities both for the linear case and for the toroidal case are discussed. (author)
Green functions in an external electric field
International Nuclear Information System (INIS)
Gavrilov, S.P.; Gitman, D.M.; Shvartsman, Sh.M.
1979-01-01
In the framework of scalar quantum electrodynamics, when vacuum is unstable as to the birth of electron-positron couples, calculated have been Green functions for the case of stable homogeneous electric field. By summing corresponding solutions of the Klein-Gordon equation of the Green function are obtained in the form of contour integrals according to the proper time. Operation representations of all the calculated Green functions in the mentioned field are presented
Separation of the Magnetic Field into External and Internal Parts
DEFF Research Database (Denmark)
Olsen, Nils; Glassmeier, K.-H.; Jia, X.
2010-01-01
The magnetic field of a planet or a planetary moon contains contributions from a variety of sources in the environment of the body (external sources) and its interior (internal sources). This chapter describes different methods that have been developed for the separation of external and internal...
Unsworth, Nash; Brewer, Gene A; Spillers, Gregory J
2010-06-01
The dynamics of correct and error responses in a variant of delayed free recall were examined in the present study. In the externalized free recall paradigm, participants were presented with lists of words and were instructed to subsequently recall not only the words that they could remember from the most recently presented list, but also any other words that came to mind during the recall period. Externalized free recall is useful for elucidating both sampling and postretrieval editing processes, thereby yielding more accurate estimates of the total number of error responses, which are typically sampled and subsequently edited during free recall. The results indicated that the participants generally sampled correct items early in the recall period and then transitioned to sampling more erroneous responses. Furthermore, the participants generally terminated their search after sampling too many errors. An examination of editing processes suggested that the participants were quite good at identifying errors, but this varied systematically on the basis of a number of factors. The results from the present study are framed in terms of generate-edit models of free recall.
Surface states in an external electric field
International Nuclear Information System (INIS)
Steslicka, M.
1975-10-01
Under conditions typical for field ion microscopy, true surface states can exist. Their shift towards higher energies can be quite significant and, moreover, additional surface levels at still higher energies can appear. The latter can play an important role in the process of tunneling of image gas electrons into surface states
On the relativistic particle dynamics in external gravitational fields
International Nuclear Information System (INIS)
Kuz'menkov, L.S.; Naumov, N.D.
1977-01-01
On the base of the Riemann metrics of an event space, leading to the Newton mechanics at nonrelativistic velocities and not obligatory weak gravitational fields relativistic particle dynamics in external gravitation fields has been considered. Found are trajectories, motion laws and light ray equations for the homogeneous and Newton fields
Superconducting Sphere in an External Magnetic Field Revisited
Sazonov, Sergey N.
2013-01-01
The purpose of this article is to give the intelligible procedure for undergraduate students to grasp proof of the fact that the magnetic field outside the hollow superconducting sphere (superconducting shell) coincides with the field of a point magnetic dipole both when an uniform external magnetic field is applied as when a ferromagnetic sphere…
Plasma cluster acceleration by means of external magnetic fields
International Nuclear Information System (INIS)
Kracik, J.; Maloch, J.; Sobra, K.
1975-01-01
The electromagnetic shock tubes are used not only for shock wave creation and study but also for pulse plasma acceleration. By applying the rail acceleration the external magnetic field perpendicular to the plasma cluster velocity can be increased. In the present work is theoretically and experimentally confirmed the external magnetic field influence on the plasma cluster acceleration when the 'snow plough' model is used. (Auth.)
International Nuclear Information System (INIS)
Coelho, R.; Lazzaro, E.
2000-01-01
The unlocking of static resistive tearing modes by rotating external magnetic perturbations such as those which may arise from the natural tokamak error-field is discussed. For a single mode the balance between the accelerating torque imparted by the error-field and the braking torque due to the interaction of the mode with the wall sets a threshold for the error-field current [H. P. Furth et al. Phys. Fluids 6, 459 (1963)], below which the mode frequency will not lock to the error-field frequency. If the mode resonant with the error-field is coupled to another mode with a rational surface located elsewhere in the plasma, the unlocking process is more elaborated and substantial modifications to the current threshold are expected. The present analysis may contribute to the explanation of some mode unlocking events in tokamak discharges with a non negligible error-field. (orig.)
Calculations in external fields in quantum chromodynamics
International Nuclear Information System (INIS)
Novikov, V.A.; Shifman, M.A.; Vairshtejn, A.I.; Zakharov, V.I.
1983-01-01
The technique of calculation of operator expansion coefficients is reviewed. The main emphasis is put on gluon operators which appear in expansion of n-point functions induced by colourless quark currents. Two convenient schemes are discussed in detail: the abstract operator method and the method based on the Fock-Schwinger gauge for the vacuum gluon field. A large number of instructive examples important from the point of view of physical applications is considered
Field Evaluation of the System Identification Approach for Tension Estimation of External Tendons
Directory of Open Access Journals (Sweden)
Myung-Hyun Noh
2015-01-01
Full Text Available Various types of external tendons are considered to verify the applicability of tension estimation method based on the finite element model with system identification technique. The proposed method is applied to estimate the tension of benchmark numerical example, model structure, and field structure. The numerical and experimental results show that the existing methods such as taut string theory and linear regression method show large error in the estimated tension when the condition of external tendon is different with the basic assumption used during the derivation of relationship between tension and natural frequency. However, the proposed method gives reasonable results for all of the considered external tendons in this study. Furthermore, the proposed method can evaluate the accuracy of estimated tension indirectly by comparing the measured and calculated natural frequencies. Therefore, the proposed method can be effectively used for field application of various types of external tendons.
Schwinger terms from external field problems
Ekstrand, Christian
1999-01-01
The current algebra for second quantized chiral fermions in an external eld contains Schwinger terms. These are studied in two di erent ways. Both are non-perturbative and valid for arbitrary odd dimension of the physical space, although explicit expressions are only given for lower dimensions. The thesis is an introductory text to the four appended research papers. In the rst two papers, Schwinger terms are studied by realizing gauge transformations as linear operators acting on sections of the bundle of Fock spaces parametrized byvector potentials. Bosons and fermions are mixed in a Z2-graded fashion. Charged particles are considered in the rst paper and neutral particles in the second. In the the third and the fourth paper, Schwinger terms are identi ed with cocycles obtained from the family index theorem for a manifold with boundary. A generating form for the covariant anomaly and Schwinger term is obtained in the third paper. The rst three papers consider Yang-Mills while the fourth (in cooperation with Jouko Mickelsson) also includes gravitation. Key words: Schwinger terms, external anomaly, Z2-grading, index theory. eld problems, higher dimensions, chiral iii iv Preface This thesis will be about Schwinger terms. It is terms that appear in equal time commutators of currents in quantum eld theory. As a mathematical physicist I nd it hard to write a thesis about this subject. Both the physical and mathematical aspects should preferably be covered. Ihavedecided to focus on some of the mathematical tools that the Schwinger term and the closely related chiral anomaly have in common. This is part of what I have learned during the years 1994{1999 as a graduate student attheRoyal Institute of Technology. The following conventions and assumptions will be made throughout the thesis: All manifolds are assumed to be second countable and Hausdor . They are assumed to be paracompact whenever a partition of unity argument is needed. In nite-dimensional manifolds are also
Error correcting circuit design with carbon nanotube field effect transistors
Liu, Xiaoqiang; Cai, Li; Yang, Xiaokuo; Liu, Baojun; Liu, Zhongyong
2018-03-01
In this work, a parallel error correcting circuit based on (7, 4) Hamming code is designed and implemented with carbon nanotube field effect transistors, and its function is validated by simulation in HSpice with the Stanford model. A grouping method which is able to correct multiple bit errors in 16-bit and 32-bit application is proposed, and its error correction capability is analyzed. Performance of circuits implemented with CNTFETs and traditional MOSFETs respectively is also compared, and the former shows a 34.4% decrement of layout area and a 56.9% decrement of power consumption.
Polarization of the vacuum by a stochastic external field
International Nuclear Information System (INIS)
Krive, I.V.; Pastur, L.A.; Rozhavskii, A.S.
1988-01-01
The effect of disorder, realized in the form of a fluctuating extra mass term, on the bosonic vacuum and fermionic vacuum of models of quantum field theory is studied. A method is developed for calculating the mean effective potential in the stochastic external field. For a model of interacting scalar and fermion fields in (3+1)-dimensional space-time it is shown that random fluctuations of the mass lead to an increase of the equilibrium mean scalar field in the system
Problems of quantum electrodynamics with external field creating pairs
International Nuclear Information System (INIS)
Fradkin, E.S.; Gitman, D.M.
1979-11-01
This paper is a preliminary version of a review of the results obtained by the authors and their collaborators which mainly concern problems of quantum electrodynamics with the pair-creating external field. In this paper the Furry picture is constructed for quantum electrodynamics with the pair-creating external field. It is shown, that various Green functions in the external field arise in the theory in a natural way. Special features of usage of the unitarity conditions for calculating the total probabilities of transitions are discussed. Perturbation theory for determining the mean electromagnetic field is constructed. Effective Lagrangians for pair-creating fields are built. One of the possible ways to introduce external field in quantum electrodynamics is considered. All the Green functions arising in the theory suggested are calculated for a constant field and a plane wave field. For the case of the electric field the total probability of creation of pairs from the vacuum accompanied by the photon irradiation and the total probability of transition from a single-electron state accompanied by the photon irradiation and creation of pairs are obtained by using the formulated rules for calculating the total probabilities of transitions. (author)
QCD Sum Rule External Field Approach and Vacuum Susceptibilities
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; PING Jia-Lun; CHANG Chao-His; WANG Fan; ZHAO En-Guang
2002-01-01
Based on QCD sum rule three-point and two-point external field formulas respectively, the vector vacuumsusceptibilities are calculated at the mean-field level in the framework of the global color symmetry model. It is shownthat the above two approaches of determination of the vector vacuum susceptibility may lead to different results. Thereason of this contradiction is discussed.
External Mask Based Depth and Light Field Camera
2013-12-08
External mask based depth and light field camera Dikpal Reddy NVIDIA Research Santa Clara, CA dikpalr@nvidia.com Jiamin Bai University of California...passive depth acquisition technology is illustrated by the emergence of light field camera companies like Lytro [1], Raytrix [2] and Pelican Imaging
Confinement of laser plasma expansion with strong external magnetic field
Tang, Hui-bo; Hu, Guang-yue; Liang, Yi-han; Tao, Tao; Wang, Yu-lin; Hu, Peng; Zhao, Bin; Zheng, Jian
2018-05-01
The evolutions of laser ablation plasma, expanding in strong (∼10 T) transverse external magnetic field, were investigated in experiments and simulations. The experimental results show that the magnetic field pressure causes the plasma decelerate and accumulate at the plasma-field interface, and then form a low-density plasma bubble. The saturation size of the plasma bubble has a scaling law on laser energy and magnetic field intensity. Magnetohydrodynamic simulation results support the observation and find that the scaling law (V max ∝ E p /B 2, where V max is the maximum volume of the plasma bubble, E p is the absorbed laser energy, and B is the magnetic field intensity) is effective in a broad laser energy range from several joules to kilo-joules, since the plasma is always in the state of magnetic field frozen while expanding. About 15% absorbed laser energy converts into magnetic field energy stored in compressed and curved magnetic field lines. The duration that the plasma bubble comes to maximum size has another scaling law t max ∝ E p 1/2/B 2. The plasma expanding dynamics in external magnetic field have a similar character with that in underdense gas, which indicates that the external magnetic field may be a feasible approach to replace the gas filled in hohlraum to suppress the wall plasma expansion and mitigate the stimulated scattering process in indirect drive ignition.
Measurement of the magnetic field errors on TCV
International Nuclear Information System (INIS)
Piras, F.; Moret, J.-M.; Rossel, J.X.
2010-01-01
A set of 24 saddle loops is used on the Tokamak a Configuration Variable (TCV) to measure the radial magnetic flux at different toroidal and vertical positions. The new system is calibrated together with the standard magnetic diagnostics on TCV. Based on the results of this calibration, the effective current in the poloidal field coils and their position is computed. These corrections are then used to compute the distribution of the error field inside the vacuum vessel for a typical TCV discharge. Since the saddle loops measure the magnetic flux at different toroidal positions, the non-axisymmetric error field is also estimated and correlated to a shift or a tilt of the poloidal field coils.
Impact of error fields on plasma identification in ITER
Energy Technology Data Exchange (ETDEWEB)
Martone, R., E-mail: Raffaele.Martone@unina2.it [Ass. EURATOM/ENEA/CREATE, Seconda Università di Napoli, Via Roma 29, Aversa (CE) (Italy); Appel, L. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Chiariello, A.G.; Formisano, A.; Mattei, M. [Ass. EURATOM/ENEA/CREATE, Seconda Università di Napoli, Via Roma 29, Aversa (CE) (Italy); Pironti, A. [Ass. EURATOM/ENEA/CREATE, Università degli Studi di Napoli “Federico II”, Via Claudio 25, Napoli (Italy)
2013-10-15
Highlights: ► The paper deals with the effect on plasma identification of error fields generated by field coils manufacturing and assembly errors. ► EFIT++ is used to identify plasma gaps when poloidal field coils and central solenoid coils are deformed, and the gaps sensitivity with respect to such errors is analyzed. ► Some examples of reconstruction errors in the presence of deformations are reported. -- Abstract: The active control of plasma discharges in present Tokamak devices must be prompt and accurate to guarantee expected performance. As a consequence, the identification step, calculating plasma parameters from diagnostics, should provide in a very short time reliable estimates of the relevant quantities, such as plasma centroid position, plasma-wall distances at given points called gaps, and other geometrical parameters as elongation and triangularity. To achieve the desired response promptness, a number of simplifying assumptions are usually made in the identification algorithms. Among those clearly affecting the quality of the plasma parameters reconstruction, one of the most relevant is the precise knowledge of the magnetic field produced by active coils. Since uncertainties in their manufacturing and assembly process may cause misalignments between the actual and expected geometry and position of magnets, an analysis on the effect of possible wrong information about magnets on the plasma shape identification is documented in this paper.
Bakic, Jasmina; Pourtois, Gilles; Jepma, Marieke; Duprat, Romain; De Raedt, Rudi; Baeken, Chris
2017-01-01
Major depressive disorder (MDD) creates debilitating effects on a wide range of cognitive functions, including reinforcement learning (RL). In this study, we sought to assess whether reward processing as such, or alternatively the complex interplay between motivation and reward might potentially account for the abnormal reward-based learning in MDD. A total of 35 treatment resistant MDD patients and 44 age matched healthy controls (HCs) performed a standard probabilistic learning task. RL was titrated using behavioral, computational modeling and event-related brain potentials (ERPs) data. MDD patients showed comparable learning rate compared to HCs. However, they showed decreased lose-shift responses as well as blunted subjective evaluations of the reinforcers used during the task, relative to HCs. Moreover, MDD patients showed normal internal (at the level of error-related negativity, ERN) but abnormal external (at the level of feedback-related negativity, FRN) reward prediction error (RPE) signals during RL, selectively when additional efforts had to be made to establish learning. Collectively, these results lend support to the assumption that MDD does not impair reward processing per se during RL. Instead, it seems to alter the processing of the emotional value of (external) reinforcers during RL, when additional intrinsic motivational processes have to be engaged. © 2016 Wiley Periodicals, Inc.
On Ising - Onsager problem in external magnetic field
International Nuclear Information System (INIS)
Kochmanski, M.S.
1997-01-01
In this paper a new approach to solving the Ising - Onsager problem in external magnetic field is investigated. The expression for free energy on one Ising spin in external field both for the two dimensional and three dimensional Ising model with interaction of the nearest neighbors are derived. The representations of free energy being expressed by multidimensional integrals of Gauss type with the appropriate dimensionality are shown. Possibility of calculating the integrals and the critical indices on the base of the derived representations for free energy is investigated
Momentum dependence in pair production by an external field
Asakawa, M.
1992-08-01
The transverse and the longitudinal momentum dependences of the pair production under an adiabatically exerted uniform abelian external field are calculated with their importance in models for the production of quark-gluon plasma in ultrarelativistic heavy ion collisions in mind. The importance of the initial condition is revealed. We show that superposition of acceleration by the external field and barrier penetration is reflected in the longitudinal momentum dependence. The peculiar nature of the boost invariant system which is expected to be approximately realized in ultrarelativistic nuclear collisions is pointed out.
Momentum dependence in pair production by an external field
International Nuclear Information System (INIS)
Asakawa, M.
1992-01-01
The transverse and the longitudinal momentum dependences of the pair production under an adiabatically exerted uniform abelian external field are calculated with their importance in models for the production of quark-gluon plasma in ultrarelativistic heavy ion collisions in mind. The importance of the initial condition is revealed. We show that superposition of acceleration by the external field and barrier penetration is reflected in the longitudinal momentum dependence. The peculiar nature of the boost invariant system which is expected to be approximately realized in ultrarelativistic nuclear collisions is pointed out. (orig.)
Dirac bound states of anharmonic oscillator in external fields
International Nuclear Information System (INIS)
Hamzavi, Majid; Ikhdair, Sameer M.; Falaye, Babatunde J.
2014-01-01
We explore the effect of the external magnetic and Aharonov–Bohm (AB) flux fields on the energy levels of Dirac particle subjects to mixed scalar and vector anharmonic oscillator field in the two-dimensional (2D) space. We calculate the exact energy eigenvalues and the corresponding un-normalized two-spinor-components wave functions in terms of the chemical potential parameter, magnetic field strength, AB flux field and magnetic quantum number by using the Nikiforov–Uvarov (NU) method. -- Highlights: • Effect of the external fields on the energy levels of Dirac particle with the anharmonic oscillator is investigated. • The solutions are discussed in view of spin and pseudospin symmetries limits. • The energy levels and wave function are presented by the Nikiforov–Uvarov method
Laser ablation of titanium in liquid in external electric field
Energy Technology Data Exchange (ETDEWEB)
Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)
2015-09-01
Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.
Coherent error study in a retarding field energy analyzer
International Nuclear Information System (INIS)
Cui, Y.; Zou, Y.; Reiser, M.; Kishek, R.A.; Haber, I.; Bernal, S.; O'Shea, P.G.
2005-01-01
A novel cylindrical retarding electrostatic field energy analyzer for low-energy beams has been designed, simulated, and tested with electron beams of several keV, in which space charge effects play an important role. A cylindrical focusing electrode is used to overcome the beam expansion inside the device due to space-charge forces, beam emittance, etc. In this paper, we present the coherent error analysis for this energy analyzer with beam envelope equation including space charge and emittance effects. The study shows that this energy analyzer can achieve very high resolution (with relative error of around 10 -5 ) if taking away the coherent errors by using proper focusing voltages. The theoretical analysis is compared with experimental results
On the axial anomalies in external tensor fields
International Nuclear Information System (INIS)
Khudaverdyan, O.M.; Mkrtchyan, R.L.; Zurabyan, L.A.
1985-01-01
Computation of the axial anomaly for Dirac fermions in external tensor fields is studied. The sequence of the supersymmetric one-dimensional models is presented. Their supercharges are equal, after quantization, to Dirac operators in external tensor fields, and the density of Witten's partition function gives the anomaly. It is shown that action in the corresponding path integral differs from the classical one. Gaussian approximation gives the anomaly only in the case of third-rank tensor with zero exterior derivative and in that case anomaly is calculated in all dimensions. The interpretation of that field as the torsion of gravitational field and also connection with the results of Witten and Alvarez-Gaume and Atiyah-Singer index theorem are discussed
Energy Technology Data Exchange (ETDEWEB)
Harrington, B J; Shepard, H K [New Hampshire Univ., Durham (USA). Dept. of Physics
1976-03-22
By fully exploiting the mathematical and physical analogy to the Ginzburg-Landau theory of superconductivity, a complete discussion of the ground state behavior of the four-dimensional Abelian Higgs model in the static tree level approximation is presented. It is shown that a sufficiently strong external magnetic field can alter the ground state of the theory by restoring a spontaneously broken symmetry, or by creating a qualitatively different 'vortex' state. The energetically favored ground state is explicitly determined as a function of the external field and the ratio between coupling constants of the theory.
On the roles of direct feedback and error field correction in stabilizing resistive-wall modes
International Nuclear Information System (INIS)
In, Y.; Bogatu, I.N.; Kim, J.S.; Garofalo, A.M.; Jackson, G.L.; La Haye, R.J.; Schaffer, M.J.; Strait, E.J.; Lanctot, M.J.; Reimerdes, H.; Marrelli, L.; Martin, P.; Okabayashi, M.
2010-01-01
Active feedback control in the DIII-D tokamak has fully stabilized the current-driven ideal kink resistive-wall mode (RWM). While complete stabilization is known to require both low frequency error field correction (EFC) and high frequency feedback, unambiguous identification has been made about the distinctive role of each in a fully feedback-stabilized discharge. Specifically, the role of direct RWM feedback, which nullifies the RWM perturbation in a time scale faster than the mode growth time, cannot be replaced by low frequency EFC, which minimizes the lack of axisymmetry of external magnetic fields. (letter)
Superconductive magnetic energy storage (SMES) external fields and safety considerations
International Nuclear Information System (INIS)
Polk, C.; Boom, R.W.; Eyssa, Y.M.
1992-01-01
This paper addresses preferred SMES configurations and the external magnetic fields which they generate. Possible biological effects of fields are reviewed briefly. It is proposed that SMES units be fenced at the 10 gauss (1 mT) level to keep unrestricted areas safe, even for persons with cardiac pacemakers. For a full size 5000 MWh (1.8 x 10 13 J) SMES the magnetic field decreases to 10 gauss at a radial distance of 2 km from the center of the coil. Other considerations related to the environmental impact of large SMES magnetic fields are discussed briefly
Quantum description of the Brownian movement in an external field
International Nuclear Information System (INIS)
Svin'in, I.R.
1976-01-01
The Schroedinger equation for brownian motion in an external field is obtained on the basis of the classical Langevin equation. The specific features of the approach proposed are illustrated by the example of the brownian motion of the quantum oscillator. The influence of the fluctuations on the various physical quantities is considered
Dielectric permittivity of a plasma in an external electric field
International Nuclear Information System (INIS)
Schweigert, V.A.
2001-01-01
The ion contribution to the dielectric function of a plasma in an external electric field is determined by applying a kinetic approach to the ions in a parent gas in which the main mechanism for ion scattering is resonant charge exchange. The ion scattering frequency is assumed to be constant
Correlation effects in the Ising model in an external field
International Nuclear Information System (INIS)
Borges, H.E.; Silva, P.R.
1983-01-01
The thermodynamic properties of the spin-1/2 Ising Model in an external field are evaluated through the use of the exponential differential operator method and Callen's exact relations. The correlations effects are treated in a phenomenological approach and the results are compared with other treatments. (Author) [pt
Internal and external Field of View: computer games and cybersickness
Vries, S.C. de; Bos, J.E.; Emmerik, M.L. van; Groen, E.L.
2007-01-01
In an experiment with a computer game environment, we studied the effect of Field-of-View (FOV) on cybersickness. In particular, we examined the effect of differences between the internal FOV (IFOV, the FOV which the graphics generator is using to render its images) and the external FOV (EFOV, the
Quantization of fermions in external soliton fields and index calculation
International Nuclear Information System (INIS)
Grosse, H.
1986-01-01
We review recent results on the quantization of fermions in external fields, discuss equivalent and inequivalent representations of the canonical anticommutation relations, indicate how the requirement of implementability of gauge transformations leads to quantization conditions, determine the algebra of charges, identify the Schwinger term and remark finally how one may calculate a ground state charge. (Author)
Holographic gratings in photorefractive polymers without external electric field
DEFF Research Database (Denmark)
Kukhtarev, N.; Lyuksyutov, S.; Buchhave, Preben
1997-01-01
Using anomalous large diffusion we report a recording of reflection type gratings in a PVK-based photorefractive polymer without any external electric field. The diffraction efficiency of the gratings was measured to be 7%. An efficient modulation of beams during two-beam coupling up to 12...
A relativistic colored spinning particle in an external color field
International Nuclear Information System (INIS)
Heinz, U.
1984-01-01
I derive fully covariant equations of motion for a classical colored spinning particle in an external SU(3) color field. Although the total color charge and total spin of the particle are found to be separately constants of motion (here I disagree with a recent paper by Arodz), the dynamics of the orientation of the color and spin vectors are coupled to each other through interaction with the color field, even if the latter is homogeneous. (orig.)
Decadal period external magnetic field variations determined via eigenanalysis
DEFF Research Database (Denmark)
Shore, R. M.; Whaler, K. A.; Macmillan, S.
2016-01-01
to a full solar cycle. Our analysis focuses on geomagnetically quiet days and middle to low latitudes. We use the climatological eigenanalysis technique called empirical orthogonal functions (EOFs), which allows us to identify discrete spatiotemporal patterns with no a priori specification of their geometry...... mean external field distribution. Separate patterns of semiannual and solar-cycle-length periods appear to stem from the amplitude modulations of spatially fixed background fields....
Fluorescence excitation studies of molecular photoionization in external electric fields
International Nuclear Information System (INIS)
Poliakoff, E.D.; Dehmer, J.L.; Parr, A.C.; Leroi, G.E.
1985-01-01
Using molecular nitrogen as an example, we show that fluorescence excitation spectroscopy can be used to measure partial photoionization cross sections of free molecules in external electric fields. The production of the N 2 + (B 2 Σ/sub u/ + ) state was studied and the threshold for this process was found to shift linearly with the square root of the applied field. This behavior is compared with the hydrogenic case and with previously studied systems
Effect of External Electric Field Stress on Gliadin Protein Conformation
Singh, Ashutosh; Munshi, Shirin; Raghavan, Vijaya
2013-01-01
A molecular dynamic (MD) modeling approach was applied to evaluate the effect of external electric field on gliadin protein structure and surface properties. Static electric field strengths of 0.001 V/nm and 0.002 V/nm induced conformational changes in the protein but had no significant effect on its surface properties. The study of hydrogen bond evolution during the course of simulation revealed that the root mean square deviation, radius of gyration and secondary structure formation, all de...
Radiative decay of coupled states in an external dc field
International Nuclear Information System (INIS)
Pal'chikov, V.; Sokolov, Y.; Yakovlev, V.
2001-01-01
This paper examines two theoretical aspects of the interference of atomic states in hydrogen which comes from the application of an external electric field F to the 2s metastable state. The radiative corrections to the Bethe-Lamb formula and anisotropy contribution to the angular distribution, which arises from interference between electric-field-induced E1-radiation and forbidden M1-radiation, are analysed
Radiative decay of coupled states in an external dc field
Energy Technology Data Exchange (ETDEWEB)
Pal' chikov, V. [National Research Inst. for Physical-Technical and Radiotechnical Measurements (VNIIFTRI), Mendeleevo, Moscow Region (Russian Federation); Sokolov, Y. [Kurchatov Inst., Russian Research Centre, Moscow (Russian Federation); Yakovlev, V. [Moscow Engineering Physics Inst., Moscow (Russian Federation)
2001-07-01
This paper examines two theoretical aspects of the interference of atomic states in hydrogen which comes from the application of an external electric field F to the 2s metastable state. The radiative corrections to the Bethe-Lamb formula and anisotropy contribution to the angular distribution, which arises from interference between electric-field-induced E1-radiation and forbidden M1-radiation, are analysed.
A new controller for the JET error field correction coils
International Nuclear Information System (INIS)
Zanotto, L.; Sartori, F.; Bigi, M.; Piccolo, F.; De Benedetti, M.
2005-01-01
This paper describes the hardware and the software structure of a new controller for the JET error field correction coils (EFCC) system, a set of ex-vessel coils that recently replaced the internal saddle coils. The EFCC controller has been developed on a conventional VME hardware platform using a new software framework, recently designed for real-time applications at JET, and replaces the old disruption feedback controller increasing the flexibility and the optimization of the system. The use of conventional hardware has required a particular effort in designing the software part in order to meet the specifications. The peculiarities of the new controller will be highlighted, such as its very useful trigger logic interface, which allows in principle exploring various error field experiment scenarios
Verification of setup errors in external beam radiation therapy using electronic portal imaging
International Nuclear Information System (INIS)
Krishna Murthy, K.; Al-Rahbi, Zakiya; Sivakumar, S.S.; Davis, C.A.; Ravichandran, R.
2008-01-01
The objective of this study was to conduct an audit on QA aspects of treatment delivery by the verification of the treatment fields position on different days to document the efficiency of immobilization methods and reproducibility of treatment. A retrospective study was carried out on 60 patients, each 20 treated for head and neck, breast, and pelvic sites; and a total of 506 images obtained by electronic portal imaging device (EPID) were analyzed. The portal images acquired using the EPID systems attached to the Varian linear accelerators were superimposed on the reference images. The anatomy matching software (Varian portal Vision. 6.0) was used, and the displacements in two dimensions and rotation were noted for each treated field to study the patient setup errors. The percentages of mean deviations more than 3 mm in lateral (X) and longitudinal (Y) directions were 17.5%, 11.25%, and 7.5% for breast, pelvis, and head and neck cases respectively. In all cases, the percentage of mean deviation with more than 5 mm error was 0.83%. The maximum average mean deviation in all the cases was 1.87. The average mean SD along X and Y directions in all the cases was less than 2.65. The results revealed that the ranges of setup errors are site specific and immobilization methods improve reproducibility. The observed variations were well within the limits. The study confirmed the accuracy and quality of treatments delivered to the patients. (author)
Photoproduction of gravitons and dilatons in an external electromagnetic field
International Nuclear Information System (INIS)
Le Khac Huong; Hoang Ngoc Long.
1990-07-01
An attempt is made to present experimental predictions of the Kaluza-Klein based models. We consider the creation of gravitons and dilatons by photons in an external electromagnetic field, namely in the electric field of a flat condenser and in the static magnetic field. The relation between the cross sections of these two processes is given. A numerical evaluation shows that in the present technical scenario the creation of high frequency gravitons and dilatons may be indirectly observable. (author). 10 refs, 2 figs
Lepton-photon interactions in external background fields
Energy Technology Data Exchange (ETDEWEB)
Akal, Ibrahim [Theory Group, Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, D-22607 Hamburg (Germany); Moortgat-Pick, Gudrid [II. Institute for Theoretical Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany)
2016-07-01
We investigate lepton-photon interactions in a class of generalized external background fields with periodic plane-wave character. Considering the full interaction with the background, S-matrix elements are calculated exactly. We apply those general expressions to interaction schemes like Compton scattering in specific field configurations, as for instance provided in modern laser facilities, or in high intense regions of future linear colliders. Results are extended to the case of frontal colliding high-energy field photons with leptons such that new insights beyond the usual soft terms become accessible.
Toroidal plasma reactor with low external magnetic field
International Nuclear Information System (INIS)
Beklemishev, A.D.; Khayrutdinov, R.R.; Petviashvili, V.I.; Tajima, T.; Gordin, V.A.; Tajima, T.
1991-01-01
A toroidal pinch configuration with safety factor q < 0.5 decreasing from the center to periphery without field reversal is proposed. This is capable of containing high pressure plasma with only small toroidal external magnetic field. Sufficient conditions for magnetohydrodynamic stability are fulfilled in this configuration. The stability is studied by constructing the Lyapunov functional and investigating its extrema both analytically and numerically. Comparison of the Lyapunov stability conditions with the conventional linear theory is carried out. Stable configurations are found with average β near 15%, with magnetic field associated mainly with plasma current. The β value calculated with the external magnetic field can be over 100%. Fast charged particles produced by fusion reactions are asymmetrically confined by the poloidal magnetic field (and due to the lack of strong toroidal field). They thus generate a current in the noncentral part of plasma to reinforce the poloidal field. This current drive can sustain the monotonic decrease of q with radius. 20 refs., 9 figs
International Nuclear Information System (INIS)
Lobashev, A.A.; Mostepanenko, V.M.
1993-01-01
Heisenberg formalism is developed for creation-annihilation operators of quantum fields propagating in nonstationary external fields. Quantum fields with spin 0,1/2, 1 are considered in the presence of such external fields as electromagnetic, scalar and the field of nonstationary dielectric properties of nonlinear medium. Elliptic operator parametrically depending on time is constructed. In Heisenberg representation field variables are decomposed over eigenfunction of this operator. The relation between Heisenberg creation-annihilation operators and the operators obtained in the frame of diagonalization of Hamiltonian with Bogoliubov transformations is set up
Calculation of magnetic error fields in hybrid insertion devices
International Nuclear Information System (INIS)
Savoy, R.; Halbach, K.; Hassenzahl, W.; Hoyer, E.; Humphries, D.; Kincaid, B.
1989-08-01
The Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory requires insertion devices with fields sufficiently accurate to take advantage of the small emittance of the ALS electron beam. To maintain the spectral performance of the synchrotron radiation and to limit steering effects on the electron beam these errors must be smaller than 0.25%. This paper develops a procedure for calculating the steering error due to misalignment of the easy axis of the permanent magnet material. The procedure is based on a three dimensional theory of the design of hybrid insertion devices developed by one of us. The acceptable tolerance for easy axis misalignment is found for a 5 cm period undulator proposed for the ALS. 11 refs., 5 figs
Floating and flying ferrofluid bridges induced by external magnetic fields
Ma, Rongchao; Zhou, Yixin; Liu, Jing
2015-04-01
A ferrofluid is a mixture that exhibits both magnetism and fluidity. This merit enables the ferrofluid to be used in a wide variety of areas. Here we show that a floating ferrofluid bridge can be induced between two separated boards under a balanced external magnetic field generated by two magnets, while a flying ferrofluid bridge can be induced under an unbalanced external magnetic field generated by only one magnet. The mechanisms of the ferrofluid bridges were discussed and the corresponding mathematical equations were also established to describe the interacting magnetic force between the ferro particles inside the ferrofluid. This work answered a basic question that, except for the well-known floating water bridges that are related to electricity, one can also build up a liquid bridge that is related to magnetism.
Pair creation by an external non-Abelian field
International Nuclear Information System (INIS)
Hamil, B; Chetouani, L
2014-01-01
The problem of the creation of particle pairs of spin 0 and 1/2 from the vacuum by an external field of a non-Abelian type plane wave on the light cone is considered following the approach of Schwinger. Using simple shifts and only by an algebraic calculation, it is shown that with this form of interaction, there is no creation of particles. (paper)
Photoabsorption of atomic hydrogen in an external DC electric field
International Nuclear Information System (INIS)
Gailitis, Modris; Gailitis, Agris
1996-01-01
An analytical approach is presented which aids the computation of the photoabsorption spectrum of atomic hydrogen in a weak external DC electric field. Separation constants in the parabolic frame and one of the normalization factors are evaluated by the Telnov algorithm. For matrix elements the series expansion after powers of parabolic coordinates is used. An enhanced precision arithmetic is applied to extract the second normalization factor from the power expansion. The results agree with those from the previous calculations and experiment. (Author)
Radical polarization in double switching of external magnetic field
International Nuclear Information System (INIS)
Lukzen, N.N.; Morozov, V.A.; Sagdeev, R.Z.
1999-01-01
Theoretical treatment of radical spin evolution under the action of double switching of external magnetic field is proposed. Account is taken of evolution of the radical spin state during laser pulse which generates paramagnetic particles. It is shown that the most effective beats in the nuclear magnetization of diamagnetic products of recombination occur upon the jump into zero magnetic field after laser pulse. The phase of observed beats bears information about the type of the initial radical polarization. The frequency of the beats is determined by radical hyperfine structure. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
Study on the plasma diode in the external magnetic field
International Nuclear Information System (INIS)
Korenev, S.A.
1981-01-01
The experimental investigations of plasma diode with cathode plasma formation on the basis of an incomplete charge over dielectric surface in the external longitudinal magnetic field with the intensity of Hsub(z) up to 2000 Oe are presented. It is demonstrated that at the 150-250 keV diode voltage and the current density of up to 300 A/cm 2 the homogeneity of the current density over transverse cross section is preserved up to the cell size of metallic grid onto cathode with the change of the magnetic field up to 2000 Oe [ru
Calculation error of collective effective dose of external exposure during works at 'Shelter' object
International Nuclear Information System (INIS)
Batij, V.G.; Derengovskij, V.V.; Kochnev, N.A.; Sizov, A.A.
2001-01-01
Collective effective dose (CED) error assessment is the most important task for optimal planning of works in the 'Shelter' object conditions. The main components of CED error are as follows: error in transient factor determination from exposition dose to equivalent dose; error in working hours determination in 'Shelter' object conditions; error in determination of dose rate at workplaces; additional CED error introduced by shielding of workplaces
Periodical plasma structures controlled by external magnetic field
Schweigert, I. V.; Keidar, M.
2017-11-01
The plasma of Hall thruster type in external magnetic field is studied in 2D3V kinetic simulations using PIC MCC method. The periodical structure with maxima of electron and ion densities is formed and becomes more pronounced with increase of magnetic field incidence angle in the plasma. These ridges of electron and ion densities are aligned with the magnetic field vector and shifted relative each other. This leads to formation of two-dimensional double-layers structure in cylindrical plasma chamber. Depending on Larmor radius and Debye length up to nineteen potential steps appear across the oblique magnetic field. The electrical current gathered on the wall is associated with the electron and ion density ridges.
The Analytical Potential Energy Function of NH Radical Molecule in External Electric Field
International Nuclear Information System (INIS)
Wu Dong-Lan; Tan Bin; Wan Hui-Jun; Xie An-Dong; Ding Da-Jun
2015-01-01
The geometric structures of an NH radical in different external electric fields are optimized by using the density functional B3P86/cc-PV5Z method, and the bond lengths, dipole moments, vibration frequencies and IR spectrum are obtained. The potential energy curves are gained by the CCSD (T) method with the same basis set. These results indicate that the physical property parameters and potential energy curves may change with the external electric field, especially in the reverse direction electric field. The potential energy function of zero field is fitted by the Morse potential, and the fitting parameters are in good accordance with the experimental data. The potential energy functions of different external electric fields are fitted adopting the constructed potential model. The fitted critical dissociation electric parameters are shown to be consistent with the numerical calculation, and the relative errors are only 0.27% and 6.61%, hence the constructed model is reliable and accurate. The present results provide an important reference for further study of the molecular spectrum, dynamics and molecular cooling with Stark effect. (paper)
International Nuclear Information System (INIS)
Efremova, S.A.; Tsarevskij, S.L.
1997-01-01
Magnetic field distribution in a unit cell of the Abrikosov vortex lattice near the surface of monoaxial anisotropic type-ii superconductors in inclined external magnetic field has been found in the framework of London model for the cases when the symmetry axis is perpendicular and parallel to the superconductor surface interface. Distribution of local magnetic field as a function of the distance from the superconductor interface surface and external field inclination angle has been obtained. Using high-Tc superconductor Y-Ba-Cu-O by way of examples, it has been shown that the study of local magnetic field distribution function, depending on external magnetic field inclination angle towards the superconductor symmetry axis and towards the superconductor surface, can provide important data on anisotropic properties of the superconductor [ru
Field error reduction experiment on the REPUTE-1 RFP device
International Nuclear Information System (INIS)
Toyama, H.; Shinohara, S.; Yamagishi, K.
1989-01-01
The vacuum chamber of the RFP device REPUTE-1 is a welded structure using 18 sets of 1 mm thick Inconel bellows (inner minor radius 22 cm) and 2.4 mm thick port segments arranged in toroidal geometry as shown in Fig. 1. The vacuum chamber is surrounded by 5 mm thick stainless steel shells. The time constant of the shell is 1 ms for vertical field penetration. The pulse length in REPUTE-1 is so far 3.2 ms (about 3 times longer than shell skin time). The port bypass plates have been attached as shown in Fig. 2 to reduce field errors so that the pulse length becomes longer and the loop voltage becomes lower. (author) 5 refs., 4 figs
Error field and its correction strategy in tokamaks
International Nuclear Information System (INIS)
In, Yongkyoon
2014-01-01
While error field correction (EFC) is to minimize the unwanted kink-resonant non-axisymmetric components, resonant magnetic perturbation (RMP) application is to maximize the benefits of pitch-resonant non-axisymmetric components. As the plasma response against non-axisymmetric field increases with beta increase, feedback-controlled EFC is a more promising EFC strategy in reactor-relevant high-beta regimes. Nonetheless, various physical aspects and uncertainties associated with EFC should be taken into account and clarified in the terms of multiple low-n EFC and multiple MHD modes, in addition to the compatibility issue with RMP application. Such a multi-faceted view of EFC strategy is briefly discussed. (author)
Dynamics of molecular superrotors in an external magnetic field
Korobenko, Aleksey; Milner, Valery
2015-08-01
We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in an external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of the molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin-rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane into three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation.
Probe branes thermalization in external electric and magnetic fields
International Nuclear Information System (INIS)
Ali-Akbari, M.; Ebrahim, H.; Rezaei, Z.
2014-01-01
We study thermalization on rotating probe branes in AdS 5 ×S 5 background in the presence of constant external electric and magnetic fields. In the AdS/CFT framework this corresponds to thermalization in the flavour sector in field theory. The horizon appears on the worldvolume of the probe brane due to its rotation in one of the sphere directions. For both electric and magnetic fields the behaviour of the temperature is independent of the probe brane dimension. We also study the open string metric and the fluctuations of the probe brane in such a set-up. We show that the temperatures obtained from open string metric and observed by the fluctuations are larger than the one calculated from the induced metric
Dynamics of molecular superrotors in an external magnetic field
International Nuclear Information System (INIS)
Korobenko, Aleksey; Milner, Valery
2015-01-01
We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in an external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of the molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin–rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane into three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation. (paper)
Relativistic covariant wave equations and acausality in external fields
International Nuclear Information System (INIS)
Pijlgroms, R.B.J.
1980-01-01
The author considers linear, finite dimensional, first order relativistic wave equations: (βsup(μ)ideltasub(μ)-β)PSI(x) = 0 with βsup(μ) and β constant matrices. Firstly , the question of the relativistic covariance conditions on these equations is considered. Then the theory of these equations with β non-singular is summarized. Theories with βsup(μ), β square matrices and β singular are also discussed. Non-square systems of covariant relativistic wave equations for arbitrary spin > 1 are then considered. Finally, the interaction with external fields and the acausality problem are discussed. (G.T.H.)
Soliton emission stimulated by sound wave or external field
International Nuclear Information System (INIS)
Malomed, B.A.
1987-01-01
Langmuir soliton interaction with ion-acoustic wave results in soliton radiative decay at the expence of emission by the soliton of linear langmuir waves. Intensity of this radiation in the ''subsonic'' regime as well as the rate of energy transfer from acoustic waves to langmuir ones and soliton decay rate are calculated. Three cases are considered: monochromatic acoustic wave, nonmonochromatic wave packet with a wide spectrum, random acoustic field, for which results appear to be qualitatively different. A related problem, concerning the radiation generation by soliton under external electromagnetic wave effect is also considered. Dissipation effect on radiation is investigated
Approximate representations of propagators in an external field
International Nuclear Information System (INIS)
Fried, H.M.
1979-01-01
A method of forming approximate representations for propagators with external field dependence is suggested and discussed in the context of potential scattering. An integro-differential equation in D+1 variables, where D represents the dimensionality of Euclidian space-time, is replaced by a Volterra equation in one variable. Approximate solutions to the latter provide a generalization of the Bloch-Nordsieck representation, containing the effects of all powers of hard-potential interactions, each modified by a characteristic soft-potential dependence [fr
Two interacting spins in external fields. Four-level systems
Energy Technology Data Exchange (ETDEWEB)
Bagrov, V.G.; Baldiotti, M.C.; Gitman, D.M. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Levin, A.D. [Dexter Research Center (United States)
2007-04-15
In the present article, we consider the so-called two-spin equation that describes four-level quantum systems. Recently, these systems attract attention due to their relation to the problem of quantum computation. We study general properties of the two-spin equation and show that the problem for certain external backgrounds can be identified with the problem of one spin in an appropriate background. This allows one to generate a number of exact solutions for two-spin equations on the basis of already known exact solutions of the one-spin equation. Besides, we present some exact solutions for the two-spin equation with an external background different for each spin but having the same direction. We study the eigenvalue problem for a time-independent spin interaction and a time-independent external background. A possible analogue of the Rabi problem for the two-spin equation is defined. We present its exact solution and demonstrate the existence of magnetic resonances in two specific frequencies, one of them coinciding with the Rabi frequency, and the other depending on the rotating field magnitude. The resonance that corresponds to the second frequency is suppressed with respect to the first one. (Abstract Copyright [2007], Wiley Periodicals, Inc.)
Phase separation in fluids exposed to spatially periodic external fields.
Vink, R L C; Archer, A J
2012-03-01
When a fluid is confined within a spatially periodic external field, the liquid-vapor transition is replaced by a different transition called laser-induced condensation (LIC) [Götze et al., Mol. Phys. 101, 1651 (2003)]. In d=3 dimensions, the periodic field induces an additional phase, characterized by large density modulations along the field direction. At the triple point, all three phases (modulated, vapor, and liquid) coexist. At temperatures slightly above the triple point and for low (high) values of the chemical potential, two-phase coexistence between the modulated phase and the vapor (liquid) is observed; by increasing the temperature further, both coexistence regions terminate in critical points. In this paper, we reconsider LIC using the Ising model to resolve a number of open issues. To be specific, we (1) determine the universality class of the LIC critical points and elucidate the nature of the correlations along the field direction, (2) present a mean-field analysis to show how the LIC phase diagram changes as a function of the field wavelength and amplitude, (3) develop a simulation method by which the extremely low tension of the interface between modulated and vapor or liquid phase can be measured, (4) present a finite-size scaling analysis to accurately extract the LIC triple point from finite-size simulation data, and (5) consider the fate of LIC in d=2 dimensions.
On charged particle equilibrium violation in external photon fields.
Bouchard, Hugo; Seuntjens, Jan; Palmans, Hugo
2012-03-01
In a recent paper by Bouchard et al. [Med. Phys. 36(10), 4654-4663 (2009)], a theoretical model of quality correction factors for idealistic so-called plan-class specific reference (PCSR) fields was proposed. The reasoning was founded on the definition of PCSR fields made earlier by Alfonso et al. [Med. Phys. 35(11), 5179-5186 (2008)], requiring the beam to achieve charged particle equilibrium (CPE), in a time-averaged sense, in the reference medium. The relation obtained by Bouchard et al. was derived using Fano's theorem (1954) which states that if CPE is established in a given medium, the dose is independent of point-to-point density variations. A potential misconception on the achievability of the condition required by Fano (1954) might be responsible for false practical conclusions, both in the definition of PCSR fields as well as the theoretical model of quality correction factor. In this paper, the practical achievability of CPE in external beams is treated in detail. The fact that this condition is not achievable in single or composite deliveries is illustrated by an intuitive method and is also formally demonstrated. Fano's theorem is not applicable in external beam radiation dosimetry without (virtually) removing attenuation effects, and therefore, the relation conditionally defined by Bouchard et al. (2009) cannot be valid in practice. A definition of PCSR fields in the recent formalism for nonstandard beams proposed by Alfonso et al. (2008) should be modified, revising the criterion of CPE condition. The authors propose reconsidering the terminology used to describe standard and nonstandard beams. The authors argue that quality correction factors of intensity modulated radiation therapy PCSR fields (i.e., k(Q(pcsr),Q) (f(pcsr),f(ref) )) could be unity under ideal conditions, but it is concluded that further investigation is necessary to confirm that hypothesis.
On charged particle equilibrium violation in external photon fields
International Nuclear Information System (INIS)
Bouchard, Hugo; Seuntjens, Jan; Palmans, Hugo
2012-01-01
Purpose: In a recent paper by Bouchard et al.[Med. Phys. 36(10), 4654-4663 (2009)], a theoretical model of quality correction factors for idealistic so-called plan-class specific reference (PCSR) fields was proposed. The reasoning was founded on the definition of PCSR fields made earlier by Alfonso et al.[Med. Phys. 35(11), 5179-5186 (2008)], requiring the beam to achieve charged particle equilibrium (CPE), in a time-averaged sense, in the reference medium. The relation obtained by Bouchard et al. was derived using Fano's theorem (1954) which states that if CPE is established in a given medium, the dose is independent of point-to-point density variations. A potential misconception on the achievability of the condition required by Fano (1954) might be responsible for false practical conclusions, both in the definition of PCSR fields as well as the theoretical model of quality correction factor. Methods: In this paper, the practical achievability of CPE in external beams is treated in detail. The fact that this condition is not achievable in single or composite deliveries is illustrated by an intuitive method and is also formally demonstrated. Conclusions: Fano's theorem is not applicable in external beam radiation dosimetry without (virtually) removing attenuation effects, and therefore, the relation conditionally defined by Bouchard et al. (2009) cannot be valid in practice. A definition of PCSR fields in the recent formalism for nonstandard beams proposed by Alfonso et al. (2008) should be modified, revising the criterion of CPE condition. The authors propose reconsidering the terminology used to describe standard and nonstandard beams. The authors argue that quality correction factors of intensity modulated radiation therapy PCSR fields (i.e., k Q pcsr ,Q f pcsr ,f ref ) could be unity under ideal conditions, but it is concluded that further investigation is necessary to confirm that hypothesis.
Particle Production under External Fields and Its Applications
Energy Technology Data Exchange (ETDEWEB)
Yoo, Hojin [Univ. of Wisconsin, Madison, WI (United States)
2014-01-01
The thesis presents studies of vacuum pair productions and its applications in early universe cosmology and high energy astrophysics. Vacuum often becomes unstable and spontaneously decays into pairs of particles in rapidly expanding universes or under strong external electromagnetic fields. Theoretically, spontaneous pair productions due to such non-trivial backgrounds of spacetimes or electromagnetic fields are well-understood. However, the effect of particle productions has not been observed so far because of experiemtal difficulties in obtaining large curvatures of space-times or strong electric fields. Although it may be impossible to observe the pair productions directly via laboratory experiments, there are still powerful sources of space-time curvatures or electric fields in cosmology and astrophysics, which result in observations. In Part I, we explore the inflationary models in early universe utilizing pair productions through gravity. We study observable signatures on the cosmic microwave background, such as isocurvature perturbations and non-Gaussianities, generated from the particle production of WIMPzillas and axions during or after inflation. In Part II, we investigate the electron-positron pair production in the magnetosphere of pulsars whose electromagnetic fields are expected to close to or even greater than the pair production threshold. In particular, we demonstrate that the pair production may be responsible for giant pulses from the Crab pulsar.
Structural stability of interaction networks against negative external fields
Yoon, S.; Goltsev, A. V.; Mendes, J. F. F.
2018-04-01
We explore structural stability of weighted and unweighted networks of positively interacting agents against a negative external field. We study how the agents support the activity of each other to confront the negative field, which suppresses the activity of agents and can lead to collapse of the whole network. The competition between the interactions and the field shape the structure of stable states of the system. In unweighted networks (uniform interactions) the stable states have the structure of k -cores of the interaction network. The interplay between the topology and the distribution of weights (heterogeneous interactions) impacts strongly the structural stability against a negative field, especially in the case of fat-tailed distributions of weights. We show that apart from critical slowing down there is also a critical change in the system structure that precedes the network collapse. The change can serve as an early warning of the critical transition. To characterize changes of network structure we develop a method based on statistical analysis of the k -core organization and so-called "corona" clusters belonging to the k -cores.
Interfacing external sensors with Android smartphones through near field communication
International Nuclear Information System (INIS)
Leikanger, Tore; Häkkinen, Juha; Schuss, Christian
2017-01-01
In this paper, we present and evaluate a new approach to communicate with inter-integrated circuit (I2C) enabled circuits such as sensors over near field communication (NFC). The NFC-to-I2C interface was designed using a non-standard NFC command to control the I2C bus directly from a smartphone, which was controlling both, the read and write operations on the I2C bus. The NFC-to-I2C interface was reporting back the data bytes on the bus to the smartphone when the transaction was completed successfully. The proposed system was tested experimentally, both, with write and read requests to a commercial microcontroller featuring a hardware I2C port, as well as reading a commercial I2C enabled humidity and temperature sensor. We present experimental results of the system which show that our approach enables an easy interface between smartphones and external sensors. Interfacing external sensors is useful and beneficial for smartphone users, especially, if certain types of sensors are not available on smartphones. (paper)
Effect of neoclassical toroidal viscosity on error-field penetration thresholds in tokamak plasmas.
Cole, A J; Hegna, C C; Callen, J D
2007-08-10
A model for field-error penetration is developed that includes nonresonant as well as the usual resonant field-error effects. The nonresonant components cause a neoclassical toroidal viscous torque that keeps the plasma rotating at a rate comparable to the ion diamagnetic frequency. The new theory is used to examine resonant error-field penetration threshold scaling in Ohmic tokamak plasmas. Compared to previous theoretical results, we find the plasma is less susceptible to error-field penetration and locking, by a factor that depends on the nonresonant error-field amplitude.
Relativistic Killingbeck energy states under external magnetic fields
International Nuclear Information System (INIS)
Eshghi, M.; Mehraban, H.; Ikhdair, S.M.
2016-01-01
We address the behavior of the Dirac equation with the Killingbeck radial potential including the external magnetic and Aharonov-Bohm (AB) flux fields. The spin and pseudo-spin symmetries are considered. The correct bound state spectra and their corresponding wave functions are obtained. We seek such a solution using the biconfluent Heun's differential equation method. Further, we give some of our results at the end of this study. Our final results can be reduced to their non-relativistic forms by simply using some appropriate transformations. The spectra, in the spin and pseudo-spin symmetries, are very similar with a slight difference in energy spacing between different states. (orig.)
Gauge invariance of a particle in an external magnetic field
International Nuclear Information System (INIS)
Ekstein, H.
1978-12-01
In the accepted theory of a nonrelativistic particle in an external field, as well as in the Dirac equation, the canonical momentum p plays a strangely elusive role: contrary to the position q, it has no physical interpretation, yet it is a member of the algebra of observables; nor does it have a well-defined meaning as a translation generator. This paper proposes an observation procedure for p which entails a definite choice for the vector potential A: the radiation gauge divergence of A=0. The canonical momentum, so defined operationally, is shown to be the image of the generator of space translations, in the sense of presymmetry, as the position q is the image of the generator of Galilei boosts in nonrelativistic theories
Relativistic Killingbeck energy states under external magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Eshghi, M. [Islamic Azad University, Researchers and Elite Club, Central Tehran Branch, Tehran (Iran, Islamic Republic of); Mehraban, H. [Semnan University, Faculty of Physics, Semnan (Iran, Islamic Republic of); Ikhdair, S.M. [An-Najah National University, Department of Physics, Faculty of Science, Nablus, West Bank, Palestine (Country Unknown); Near East University, Department of Electrical Engineering, Nicosia, Northern Cyprus (Turkey)
2016-07-15
We address the behavior of the Dirac equation with the Killingbeck radial potential including the external magnetic and Aharonov-Bohm (AB) flux fields. The spin and pseudo-spin symmetries are considered. The correct bound state spectra and their corresponding wave functions are obtained. We seek such a solution using the biconfluent Heun's differential equation method. Further, we give some of our results at the end of this study. Our final results can be reduced to their non-relativistic forms by simply using some appropriate transformations. The spectra, in the spin and pseudo-spin symmetries, are very similar with a slight difference in energy spacing between different states. (orig.)
Sensor Interaction as a Source of the Electromagnetic Field Measurement Error
Directory of Open Access Journals (Sweden)
Hartansky R.
2014-12-01
Full Text Available The article deals with analytical calculation and numerical simulation of interactive influence of electromagnetic sensors. Sensors are components of field probe, whereby their interactive influence causes the measuring error. Electromagnetic field probe contains three mutually perpendicular spaced sensors in order to measure the vector of electrical field. Error of sensors is enumerated with dependence on interactive position of sensors. Based on that, proposed were recommendations for electromagnetic field probe construction to minimize the sensor interaction and measuring error.
An investigation of coupling of the internal kink mode to error field correction coils in tokamaks
International Nuclear Information System (INIS)
Lazarus, E.A.
2013-01-01
The coupling of the internal kink to an external m/n = 1/1 perturbation is studied for profiles that are known to result in a saturated internal kink in the limit of a cylindrical tokamak. It is found from three-dimensional equilibrium calculations that, for A ≈ 30 circular plasmas and A ≈ 3 elliptical shapes, this coupling of the boundary perturbation to the internal kink is strong; i.e., the amplitude of the m/n = 1/1 structure at q = 1 is large compared with the amplitude applied at the plasma boundary. Evidence suggests that this saturated internal kink, resulting from small field errors, is an explanation for the TEXTOR and JET measurements of q 0 remaining well below unity throughout the sawtooth cycle, as well as the distinction between sawtooth effects on the q-profile observed in TEXTOR and DIII-D. It is proposed that this excitation, which could readily be applied with error field correction coils, be explored as a mechanism for controlling sawtooth amplitudes in high-performance tokamak discharges. This result is then combined with other recent tokamak results to propose an L-mode approach to fusion in tokamaks. (paper)
Effects of external field on elastic electron-ion collision in a plasma
International Nuclear Information System (INIS)
Na, Sang-Chul; Jung, Young-Dae
2008-01-01
The field effects on elastic electron-ion collision are investigated in a plasma with the presence of the external field. The eikonal method and effective interaction potential including the far-field term caused by the external field is employed to obtain the eikonal phase shift and eikonal cross section as functions of the field strength, external frequency, impact parameter, collision energy, thermal energy and Debye length. The result shows that the effect of the external field on the eikonal cross section is given by the second-order eikonal phase. In addition, the external field effects suppress the eikonal cross section as well as eikonal phase for the elastic electron-ion collision. The eikonal phase and cross section are found to be increased with an increase of the frequency of the external field. It is also shown that the eikonal cross section increases with an increase of the thermal energy and Debye length.
International Nuclear Information System (INIS)
Kanuch, T.; Miglierini, M.; Greneche, J.-M.; Skorvanek, I.; Schaaf, P.
2006-01-01
External magnetic fields are known to modify microstructure of materials during their solidification and/or crystallisation. In an external magnetic field strong particle to particle interactions lead to a highly anisotropic microstructure. If the alloy is in ferromagnetic state, stronger particle magnetization - external field interactions and also particle-to-particle couplings are expected. To reveal the magnetic texture, originally amorphous precursors of Fe 76 Mo 8 Cu 1 B 15 were annealed at 510 grad C and 550 grad C in an external longitudinal and transverse magnetic field of 0.025 T and 0.8 T, respectively. Magnetic measurements were applied to follow the changes of saturation magnetization and coercive force. Moessbauer experiments were performed at room and liquid nitrogen temperature to provide an information about orientation of with respect to an external magnetic field. The obtained results were compared with those achieved on zero field annealed samples. We can conclude that such a low external magnetic fields applied during crystallisation cause no significant changes in the magnetic microstructural anisotropy. Afterwards, magneto-optical Kerr effect (MOKE) was applied to investigate possible changes at the surface of the ribbon as a function of annealing temperature and applied magnetic field. We observed combination of uniaxial anisotropy, which originates from the shape anisotropy, and four-fold anisotropy, which is a contribution from crystallites of nanometre size embedded in the residual amorphous matrix. We expect more pronounced effects on cobalt substituted (Fe1 -x Co x ) 76 Mo 8 Cu 1 B 15 alloy. (authors)
Nonlinear error-field penetration in low density ohmically heated tokamak plasmas
International Nuclear Information System (INIS)
Fitzpatrick, R
2012-01-01
A theory is developed to predict the error-field penetration threshold in low density, ohmically heated, tokamak plasmas. The novel feature of the theory is that the response of the plasma in the vicinity of the resonant surface to the applied error-field is calculated from nonlinear drift-MHD (magnetohydrodynamical) magnetic island theory, rather than linear layer theory. Error-field penetration, and subsequent locked mode formation, is triggered once the destabilizing effect of the resonant harmonic of the error-field overcomes the stabilizing effect of the ion polarization current (caused by the propagation of the error-field-induced island chain in the local ion fluid frame). The predicted scaling of the error-field penetration threshold with engineering parameters is (b r /B T ) crit ∼n e B T -1.8 R 0 -0.25 , where b r is the resonant harmonic of the vacuum radial error-field at the resonant surface, B T the toroidal magnetic field-strength, n e the electron number density at the resonant surface and R 0 the major radius of the plasma. This scaling—in particular, the linear dependence of the threshold with density—is consistent with experimental observations. When the scaling is used to extrapolate from JET to ITER, the predicted ITER error-field penetration threshold is (b r /B T ) crit ∼ 5 × 10 −5 , which just lies within the expected capabilities of the ITER error-field correction system. (paper)
Directory of Open Access Journals (Sweden)
HUANG Motao
2016-11-01
Full Text Available Centred on the support requirement of flying track control for a long range spacecraft, a detail research is made on the computation of external disturbing gravity field, the survey accuracy of gravity anomaly on the earth' surface and the program of surveying line layout for marine gravity survey. Firstly, the solution expression of navigation error for a long range spacecraft is analyzed and modified, and the influence of the earth's gravity field on flying track of spacecraft is evaluated. Then with a given limited quota of biased error of spacecraft drop point, the accuracy requirement for calculating the external disturbing gravity field is discussed and researched. Secondly, the data truncation error and the propagated data error are studied and estimated, and the quotas of survey resolution and computation accuracy for gravity anomaly on the earth' surface are determined. Finally, based on the above quotas, a corresponding program of surveying line layout for marine gravity survey is proposed. A numerical test has been made to prove the reasonableness and validity of the suggested program.
Random errors in the magnetic field coefficients of superconducting magnets
International Nuclear Information System (INIS)
Herrera, J.; Hogue, R.; Prodell, A.; Wanderer, P.; Willen, E.
1985-01-01
Random errors in the multipole magnetic coefficients of superconducting magnet have been of continuing interest in accelerator research. The Superconducting Super Collider (SSC) with its small magnetic aperture only emphasizes this aspect of magnet design, construction, and measurement. With this in mind, we present a magnet model which mirrors the structure of a typical superconducting magnet. By taking advantage of the basic symmetries of a dipole magnet, we use this model to fit the measured multipole rms widths. The fit parameters allow us then to predict the values of the rms multipole errors expected for the SSC dipole reference design D, SSC-C5. With the aid of first-order perturbation theory, we then give an estimate of the effect of these random errors on the emittance growth of a proton beam stored in an SSC. 10 refs., 6 figs., 2 tabs
The dynamics of coupled atom and field assisted by continuous external pumping
International Nuclear Information System (INIS)
Burlak, G.; Hernandez, J.A.; Starostenko, O.
2006-01-01
The dynamics of a coupled system comprising a two-level atom and cavity field assisted by a continuous external classical field (driving Jaynes-Cummings model) is studied. When the initial field is prepared in a coherent state, the dynamics strongly depends on the algebraic sum of both fields. If this sum is zero (the compensative case) in the system, only the vacuum Rabi oscillations occur. The results with dissipation and external field detuning from the cavity field are also discussed. (Author)
The dynamics of coupled atom and field assisted by continuous external pumping
Energy Technology Data Exchange (ETDEWEB)
Burlak, G.; Hernandez, J.A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma de Morelos, Cuernavaca, Morelos (Mexico); Starostenko, O. [Departamento de Fisica, Electronica, Sistemas y Mecatronica, Universidad de las Americas, 72820 Puebla (Mexico)
2006-07-01
The dynamics of a coupled system comprising a two-level atom and cavity field assisted by a continuous external classical field (driving Jaynes-Cummings model) is studied. When the initial field is prepared in a coherent state, the dynamics strongly depends on the algebraic sum of both fields. If this sum is zero (the compensative case) in the system, only the vacuum Rabi oscillations occur. The results with dissipation and external field detuning from the cavity field are also discussed. (Author)
Hessian matrix approach for determining error field sensitivity to coil deviations
Zhu, Caoxiang; Hudson, Stuart R.; Lazerson, Samuel A.; Song, Yuntao; Wan, Yuanxi
2018-05-01
The presence of error fields has been shown to degrade plasma confinement and drive instabilities. Error fields can arise from many sources, but are predominantly attributed to deviations in the coil geometry. In this paper, we introduce a Hessian matrix approach for determining error field sensitivity to coil deviations. A primary cost function used for designing stellarator coils, the surface integral of normalized normal field errors, was adopted to evaluate the deviation of the generated magnetic field from the desired magnetic field. The FOCUS code (Zhu et al 2018 Nucl. Fusion 58 016008) is utilized to provide fast and accurate calculations of the Hessian. The sensitivities of error fields to coil displacements are then determined by the eigenvalues of the Hessian matrix. A proof-of-principle example is given on a CNT-like configuration. We anticipate that this new method could provide information to avoid dominant coil misalignments and simplify coil designs for stellarators.
Extension of Gibbs-Duhem equation including influences of external fields
Guangze, Han; Jianjia, Meng
2018-03-01
Gibbs-Duhem equation is one of the fundamental equations in thermodynamics, which describes the relation among changes in temperature, pressure and chemical potential. Thermodynamic system can be affected by external field, and this effect should be revealed by thermodynamic equations. Based on energy postulate and the first law of thermodynamics, the differential equation of internal energy is extended to include the properties of external fields. Then, with homogeneous function theorem and a redefinition of Gibbs energy, a generalized Gibbs-Duhem equation with influences of external fields is derived. As a demonstration of the application of this generalized equation, the influences of temperature and external electric field on surface tension, surface adsorption controlled by external electric field, and the derivation of a generalized chemical potential expression are discussed, which show that the extended Gibbs-Duhem equation developed in this paper is capable to capture the influences of external fields on a thermodynamic system.
Directory of Open Access Journals (Sweden)
Payam Samadi Miandoab
2016-12-01
Full Text Available Introduction Patient set-up optimization is required in radiotherapy to fill the accuracy gap between personalized treatment planning and uncertainties in the irradiation set-up. In this study, we aimed to develop a new method based on neural network to estimate patient geometrical setup using 4-dimensional (4D XCAT anthropomorphic phantom. Materials and Methods To access 4D modeling of motion of dynamic organs, a phantom employs non-uniform rational B-splines (NURBS-based Cardiac-Torso method with spline-based model to generate 4D computed tomography (CT images. First, to generate all the possible roto-translation positions, the 4D CT images were imported to Medical Image Data Examiner (AMIDE. Then, for automatic, real time verification of geometrical setup, an artificial neural network (ANN was proposed to estimate patient displacement, using training sets. Moreover, three external motion markers were synchronized with a patient couch position as reference points. In addition, the technique was validated through simulated activities by using reference 4D CT data acquired from five patients. Results The results indicated that patient geometrical set-up is highly depended on the comprehensiveness of training set. By using ANN model, the average patient setup error in XCAT phantom was reduced from 17.26 mm to 0.50 mm. In addition, in the five real patients, these average errors were decreased from 18.26 mm to 1.48 mm various breathing phases ranging from inhalation to exhalation were taken into account for patient setup. Uncertainty error assessment and different setup errors were obtained from each respiration phase. Conclusion This study proposed a new method for alignment of patient setup error using ANN model. Additionally, our correlation model (ANN could estimate true patient position with less error.
Kinetic Ising model in a time-dependent oscillating external magnetic field: effective-field theory
International Nuclear Information System (INIS)
Deviren, Bayram; Canko, Osman; Keskin, Mustafa
2010-01-01
Recently, Shi et al. [2008 Phys. Lett. A 372 5922] have studied the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field and presented the dynamic phase diagrams by using an effective-field theory (EFT) and a mean-field theory (MFT). The MFT results are in conflict with those of the earlier work of Tomé and de Oliveira, [1990 Phys. Rev. A 41 4251]. We calculate the dynamic phase diagrams and find that our results are similar to those of the earlier work of Tomé and de Oliveira; hence the dynamic phase diagrams calculated by Shi et al. are incomplete within both theories, except the low values of frequencies for the MFT calculation. We also investigate the influence of external field frequency (ω) and static external field amplitude (h 0 ) for both MFT and EFT calculations. We find that the behaviour of the system strongly depends on the values of ω and h 0 . (general)
International Nuclear Information System (INIS)
Lennernaes, B.; Letocha, H.; Rikner, G.; Magnusson, A.; Nilsson, S.
1995-01-01
The purpose of this work was to study displacement error and internal movements of the prostate during external beam radiotherapy. Verification films in the frontal (n=194) and lateral (n=64) portals were investigated in 14 patients treated with radioactive 198 Au implants. Displacement errors of two implants were investigated. In seven patients, filling of the rectum and the bladder with contrast medium or isotonic saline was performed during CT investigation for planning purposes to detect movements of the prostate. Most (95%) of the displacement errors were less than 10 mm in the frontal portal and less than 15 mm in the lateral portals. No correlation to the patient's weight was found. The displacement errors were randomly distributed. The spatial relations between the implants were not altered during the treatments. Small movements of the prostate were observed. To conclude, the positioning system employed at present (laser) can be sufficient for the margins used (2 cm). In lateral portals, however, the system did not have the ability to detect a possible systematic displacement error from simulator to accelerator. The intention is to decrease the margins to 1 cm, which will necessitate a better positioning system. (orig.)
Particle separation by external fields on periodic surfaces
International Nuclear Information System (INIS)
Sancho, J M; Khoury, M; Lindenberg, K; Lacasta, A M
2005-01-01
Particles moving on perfect periodic surfaces under the influence of external forces may move along directions that deviate from that of the force. We briefly recall previous results for transport of particles on surfaces with periodic traps or periodic obstacles driven by a constant external force, and present new results for particles moving in a harmonic periodic potential. The sorting properties are explored as a function of a number of control parameters, specifically the friction, force amplitude and direction, temperature, and lattice constants
Spin-lattice dynamics simulation of external field effect on magnetic order of ferromagnetic iron
Directory of Open Access Journals (Sweden)
C. P. Chui
2014-03-01
Full Text Available Modeling of field-induced magnetization in ferromagnetic materials has been an active topic in the last dozen years, yet a dynamic treatment of distance-dependent exchange integral has been lacking. In view of that, we employ spin-lattice dynamics (SLD simulations to study the external field effect on magnetic order of ferromagnetic iron. Our results show that an external field can increase the inflection point of the temperature. Also the model provides a better description of the effect of spin correlation in response to an external field than the mean-field theory. An external field has a more prominent effect on the long range magnetic order than on the short range counterpart. Furthermore, an external field allows the magnon dispersion curves and the uniform precession modes to exhibit magnetic order variation from their temperature dependence.
A median filter approach for correcting errors in a vector field
Schultz, H.
1985-01-01
Techniques are presented for detecting and correcting errors in a vector field. These methods employ median filters which are frequently used in image processing to enhance edges and remove noise. A detailed example is given for wind field maps produced by a spaceborne scatterometer. The error detection and replacement algorithm was tested with simulation data from the NASA Scatterometer (NSCAT) project.
Bogachkov, I. V.; Lutchenko, S. S.
2018-05-01
The article deals with the method for the assessment of the fiber optic communication lines (FOCL) reliability taking into account the effect of the optical fiber tension, the temperature influence and the built-in diagnostic equipment errors of the first kind. The reliability is assessed in terms of the availability factor using the theory of Markov chains and probabilistic mathematical modeling. To obtain a mathematical model, the following steps are performed: the FOCL state is defined and validated; the state graph and system transitions are described; the system transition of states that occur at a certain point is specified; the real and the observed time of system presence in the considered states are identified. According to the permissible value of the availability factor, it is possible to determine the limiting frequency of FOCL maintenance.
Possible effects of external electrical fields on the corrosion of copper in bentonite
Energy Technology Data Exchange (ETDEWEB)
Taxen, Claes (Swerea KIMAB (Sweden))
2011-12-15
External potentials that develop across a repository may interact with the copper canister. A study was undertaken to investigate the potential corrosion effects of voltage differences in a repository. A set of experiments was performed to study the tendency of copper in bentonite to corrode under influence of an externally applied electrical field. A model study was made to estimate possible corrosion effects of an external electrical field on a full-scale canister in the KBS-3 concept. The interaction between the repository represented by a copper canister in bentonite, and an external electrical field is illustrated with an example
External-field shifts in precision spectroscopy of hydrogen molecular ions
Energy Technology Data Exchange (ETDEWEB)
Bakalov, Dimitar, E-mail: dbakalov@inrne.bas.bg [INRNE, Bulgarian Academy of Sciences (Bulgaria); Korobov, Vladimir [Joint Institute for Nuclear Research (Russian Federation); Schiller, Stephan [Heinrich-Heine-Universitat Dusseldorf, Institut fur Experimentalphysik (Germany)
2015-08-15
The Effective Hamiltonian of the hydrogen molecular ions is a convenient tool for the evaluation of the shift of the energy levels of the ro-vibrational states and the frequencies of the transitions between them, due to external electric and magnetic fields. Using the Effective Hamiltonian, composite frequencies of suppressed susceptibility to external fields are constructed.
On quantum electrodynamics in an external gravitational field. Part 2. Discussion of the effects
International Nuclear Information System (INIS)
Lotze, K.H.
1978-01-01
The S matrix constructed in Part I of this work is evaluated for processes which it includes. Some of them are discussed in more detail: pair creation and scattering in an external gravitational field, pair creation by a photon and creation of an electron-positron pair and a photon in an external gravitational field. (author)
Duality in the U(1) Higgs model with an external field
International Nuclear Information System (INIS)
Damgaard, P.H.
1988-07-01
An external electromagnetic field is coupled to the lattice U(1) Higgs model in a Villain form. Duality transformations are then used to express the partition function in terms of an effective Lagrangian of topological excitations and their couplings to the external field. Consequences for the phase diagram are derived. (orig.)
External field as the functional of inhomogeneous density and the density matrix functional approach
Bobrov, V.B.; Trigger, S.A.; Vlasov, Y.P.
2012-01-01
Based on the Hohenberg-Kohn lemma and the hypotheses of the density functional existence for the external-field potential, it is shown that the strict result of the density functional theory is the equation of the external-field potential as the density functional. This result leads to the
Chiral symmetry breaking in d=3 NJL model in external gravitational and magnetic fields
Gitman, D. M.; Odintsov, S. D.; Shil'nov, Yu. I.
1996-01-01
The phase structure of $d=3$ Nambu-Jona-Lasinio model in curved spacetime with magnetic field is investigated in the leading order of the $1/N$-expansion and in linear curvature approximation (an external magnetic field is treated exactly). The possibility of the chiral symmetry breaking under the combined action of the external gravitational and magnetic fields is shown explicitly. At some circumstances the chiral symmetry may be restored due to the compensation of the magnetic field by the ...
Use of Earth's magnetic field for mitigating gyroscope errors regardless of magnetic perturbation.
Afzal, Muhammad Haris; Renaudin, Valérie; Lachapelle, Gérard
2011-01-01
Most portable systems like smart-phones are equipped with low cost consumer grade sensors, making them useful as Pedestrian Navigation Systems (PNS). Measurements of these sensors are severely contaminated by errors caused due to instrumentation and environmental issues rendering the unaided navigation solution with these sensors of limited use. The overall navigation error budget associated with pedestrian navigation can be categorized into position/displacement errors and attitude/orientation errors. Most of the research is conducted for tackling and reducing the displacement errors, which either utilize Pedestrian Dead Reckoning (PDR) or special constraints like Zero velocity UPdaTes (ZUPT) and Zero Angular Rate Updates (ZARU). This article targets the orientation/attitude errors encountered in pedestrian navigation and develops a novel sensor fusion technique to utilize the Earth's magnetic field, even perturbed, for attitude and rate gyroscope error estimation in pedestrian navigation environments where it is assumed that Global Navigation Satellite System (GNSS) navigation is denied. As the Earth's magnetic field undergoes severe degradations in pedestrian navigation environments, a novel Quasi-Static magnetic Field (QSF) based attitude and angular rate error estimation technique is developed to effectively use magnetic measurements in highly perturbed environments. The QSF scheme is then used for generating the desired measurements for the proposed Extended Kalman Filter (EKF) based attitude estimator. Results indicate that the QSF measurements are capable of effectively estimating attitude and gyroscope errors, reducing the overall navigation error budget by over 80% in urban canyon environment.
Three-dimensional tokamak equilibria in the presence of resonant field errors
International Nuclear Information System (INIS)
Reiman, A.; Monticello, D.
1992-01-01
Numerical solutions are described for three-dimensional MHD equilibria in the presence of resonant magnetic field perturbations. The effects of a realistic spectrum of resonant field errors are calculated for a range of current profiles. It is found that field errors of the magnitude existing in present day devices, and contemplated for future devices, can produce a set of magnetic islands occupying a significant fraction of the plasma cross-section
Error Propagation dynamics: from PIV-based pressure reconstruction to vorticity field calculation
Pan, Zhao; Whitehead, Jared; Richards, Geordie; Truscott, Tadd; USU Team; BYU Team
2017-11-01
Noninvasive data from velocimetry experiments (e.g., PIV) have been used to calculate vorticity and pressure fields. However, the noise, error, or uncertainties in the PIV measurements would eventually propagate to the calculated pressure or vorticity field through reconstruction schemes. Despite the vast applications of pressure and/or vorticity field calculated from PIV measurements, studies on the error propagation from the velocity field to the reconstructed fields (PIV-pressure and PIV-vorticity are few. In the current study, we break down the inherent connections between PIV-based pressure reconstruction and PIV-based vorticity calculation. The similar error propagation dynamics, which involve competition between physical properties of the flow and numerical errors from reconstruction schemes, are found in both PIV-pressure and PIV-vorticity reconstructions.
Quantum mean-field decoding algorithm for error-correcting codes
International Nuclear Information System (INIS)
Inoue, Jun-ichi; Saika, Yohei; Okada, Masato
2009-01-01
We numerically examine a quantum version of TAP (Thouless-Anderson-Palmer)-like mean-field algorithm for the problem of error-correcting codes. For a class of the so-called Sourlas error-correcting codes, we check the usefulness to retrieve the original bit-sequence (message) with a finite length. The decoding dynamics is derived explicitly and we evaluate the average-case performance through the bit-error rate (BER).
Influence of External Magnetic Fields on Tunneling of Spin-1 Bose Condensate
International Nuclear Information System (INIS)
Yu Zhaoxian; Jiao Zhiyong; Sun Jinzuo
2005-01-01
In this letter, we have studied the influence of the external magnetic fields on tunneling of the spin-1 Bose condensate. We find that the population transfer between spin-0 and spin-±1 exhibits the step structure under the external cosinusoidal magnetic field and a combination of static and cosinusoidal one, respectively. Compared with the longitudinal component of the external magnetic field, the smaller the transverse component of the magnetic field is, the larger the time scale of exhibiting the step structure does. The tunneling current may exhibit periodically oscillation behavior when the ratio of the transverse component of the magnetic field is smaller than that of the longitudinal component, otherwise it exhibits a damply oscillating behavior. This means that the dynamical spin localization can be adjusted by the external magnetic fields.
Electromagnetic-gravitational conversion cross sections in external electromagnetic fields
International Nuclear Information System (INIS)
Hoang Ngoc Long; Dang Van Soa; Tuan Tran, A.
1994-09-01
The classical processes: the conversion of photons into gravitons in the static electromagnetic fields are considered by using Feynman perturbation techniques. The differential cross sections are presented for the conversion in the electric field of the flat condenser and the magnetic field of the solenoid. A numerical evaluation shows that the cross sections may have the observable value in the present technical scenario. (author). 11 refs
Effect of external fields in Axelrod's model of social dynamics
Peres, Lucas R.; Fontanari, José F.
2012-09-01
The study of the effects of spatially uniform fields on the steady-state properties of Axelrod's model has yielded plenty of counterintuitive results. Here, we reexamine the impact of this type of field for a selection of parameters such that the field-free steady state of the model is heterogeneous or multicultural. Analyses of both one- and two-dimensional versions of Axelrod's model indicate that the steady state remains heterogeneous regardless of the value of the field strength. Turning on the field leads to a discontinuous decrease on the number of cultural domains, which we argue is due to the instability of zero-field heterogeneous absorbing configurations. We find, however, that spatially nonuniform fields that implement a consensus rule among the neighborhood of the agents enforce homogenization. Although the overall effects of the fields are essentially the same irrespective of the dimensionality of the model, we argue that the dimensionality has a significant impact on the stability of the field-free homogeneous steady state.
Dose estimation in embryo or fetus in external fields
International Nuclear Information System (INIS)
Gregori, Beatriz N.
2001-01-01
The embryo or the fetus can be irradiated as result of radiological procedures of diagnosis of therapy in where the beam effects directly on the same one or in tissues or peripherical organs. Some authors have suggested that in the first stages of the pregnancy the dose in ovaries can be the good estimated of the dose in embryo or fetus. In advanced conditions of the development, probably also in the early stage, is more appropriated to specify the dose in the embryo or fetus equal of the uterus. The dose in the uterus is a good estimated so much for external irradiation as for radionuclides incorporation
Two interacting spins in external fields and application to quantum computation
International Nuclear Information System (INIS)
Baldiotti, M.C.; Gitman, D.M.; Bagrov, V.G.
2009-01-01
We study the four-level system given by two quantum dots immersed in a time-dependent magnetic field, which are coupled to each other by an effective Heisenberg-type interaction. We describe the construction of the corresponding evolution operator in a special case of different time-dependent parallel external magnetic fields. We find a relation between the external field and the effective interaction function. The obtained results are used to analyze the theoretical implementation of a universal quantum gate
Energy Technology Data Exchange (ETDEWEB)
Dosch, H G [Heidelberg Univ. (F.R. Germany). Inst. fuer Theoretische Physik; Mueller, V F [Trier-Kaiserslautern Univ., Kaiserslautern (F.R. Germany). Fachbereich Physik
1975-01-01
Extending the inductive renormalization procedure of Epstein and Glaser which is essentially based on locality, we show that quantum electrodynamics in an external time independent electromagnetic field has a renormalizable formal perturbation expansion. The interaction involving the quantized radiation field but not the action of the external field is treated by perturbation theory. It turns out that vacuum polarization is undetermined in the framework of such a theory.
Relations between focusing power of space-charge lenses and external electromagnetic fields
International Nuclear Information System (INIS)
Yu Qingchang; Qiu Hong; Huang Jiachang
1991-01-01
Under different external electromagnetic fields, the electron densities of the electron cloud in a self-sustaning spece-charge lens are measured with the radio-frequency method and the energy distributions of the ions produced in ionization are measured with the stopping field method. From them the relations between the focusing power of space-charge lenses and the external electromagnetic fields are determined. The available region of the Lebedev-Morozov formula is discussed
Stable solitary waves in super dense plasmas at external magnetic fields
Ghaani, Azam; Javidan, Kurosh; Sarbishaei, Mohsen
2015-07-01
Propagation of localized waves in a Fermi-Dirac distributed super dense matter at the presence of strong external magnetic fields is studied using the reductive perturbation method. We have shown that stable solitons can be created in such non-relativistic fluids in the presence of an external magnetic field. Such solitary waves are governed by the Zakharov-Kuznetsov (ZK) equation. Properties of solitonic solutions are studied in media with different values of background mass density and strength of magnetic field.
International Nuclear Information System (INIS)
Baryshevskii, V.G.; Skadorov, V.V.
1986-01-01
A dynamical theory is developed of the Moessbauer radiation diffraction by crystals being subjected to an variable external field action. Equations describing the dynamical diffraction by nonstationary crystals are obtained. It is shown that the resonant interaction between Moessbauer radiation and shift field induced in the crystal by a variable external field giving rise to an effective conversion of the incident wave into a wave with changed frequency. (author)
Influence of calculation error of total field anomaly in strongly magnetic environments
Yuan, Xiaoyu; Yao, Changli; Zheng, Yuanman; Li, Zelin
2016-04-01
An assumption made in many magnetic interpretation techniques is that ΔTact (total field anomaly - the measurement given by total field magnetometers, after we remove the main geomagnetic field, T0) can be approximated mathematically by ΔTpro (the projection of anomalous field vector in the direction of the earth's normal field). In order to meet the demand for high-precision processing of magnetic prospecting, the approximate error E between ΔTact and ΔTpro is studied in this research. Generally speaking, the error E is extremely small when anomalies not greater than about 0.2T0. However, the errorE may be large in highly magnetic environments. This leads to significant effects on subsequent quantitative inference. Therefore, we investigate the error E through numerical experiments of high-susceptibility bodies. A systematic error analysis was made by using a 2-D elliptic cylinder model. Error analysis show that the magnitude of ΔTact is usually larger than that of ΔTpro. This imply that a theoretical anomaly computed without accounting for the error E overestimate the anomaly associated with the body. It is demonstrated through numerical experiments that the error E is obvious and should not be ignored. It is also shown that the curves of ΔTpro and the error E had a certain symmetry when the directions of magnetization and geomagnetic field changed. To be more specific, the Emax (the maximum of the error E) appeared above the center of the magnetic body when the magnetic parameters are determined. Some other characteristics about the error Eare discovered. For instance, the curve of Emax with respect to the latitude was symmetrical on both sides of magnetic equator, and the extremum of the Emax can always be found in the mid-latitudes, and so on. It is also demonstrated that the error Ehas great influence on magnetic processing transformation and inversion results. It is conclude that when the bodies have highly magnetic susceptibilities, the error E can
Hargrave, B K
2014-11-01
Speculation as to optical malfunction has led to dissatisfaction with the theory that the lens is the sole agent in accommodation and to the suggestion that other parts of the eye are also conjointly involved. Around half-a-century ago, Robert Brooks Simpkins suggested that the mechanical features of the human eye were precisely such as to allow for a lengthening of the globe when the eye accommodated. Simpkins was not an optical man but his theory is both imaginative and comprehensive and deserves consideration. It is submitted here that accommodation is in fact a twofold process, and that although involving the lens, is achieved primarily by means of a give - and - take interplay between adducting and abducting external muscles, whereby an elongation of the eyeball is brought about by a stretching of the delicate elastic fibres immediately behind the cornea. The three muscles responsible for convergence (superior, internal and inferior recti) all pull from in front backwards, while of the three abductors (external rectus and the two obliques) the obliques pull from behind forwards, allowing for an easy elongation as the eye turns inwards and a return to its original length as the abducting muscles regain their former tension, returning the eye to distance vision. In refractive errors, the altered length of the eyeball disturbs the harmonious give - and - take relationship between adductors and abductors. Such stresses are likely to be perpetuated and the error exacerbated. Speculation is not directed towards a search for a possible cause of the muscular imbalance, since none is suspected. Muscles not used rapidly lose tone, as evidenced after removal of a limb from plaster. Early attention to the need for restorative exercise is essential and results usually impressive. If flexibility of the external muscles of the eyes is essential for continuing good sight, presbyopia can be avoided and with it the supposed necessity of glasses in middle life. Early attention
Oscillations and Stability of Plasma in an External High-Frequency Electric Field
International Nuclear Information System (INIS)
Aliev, Ju.M.; Gorbunov, L.M.; Silin, V.P.; Uotson, H.
1966-01-01
A theory is developed for the oscillations and stability of plasma in a strong external HF electric field. The kinetic equation with self-congruent reciprocity is linearized for weak deviations from the ground state. Since the latter depends on an external HF field, the linearized equation obtained has coefficients with a periodic time dependence. From this equation and also from Maxwell's equations there is derived a dispersion equation for plasma oscillations that represents the zero value of the infinite order determinant, and that is solved both for external field frequencies considerably exceeding the electron Langmuir frequency and for frequencies that are less. The external HF field changes the oscillation branches in a plasma without an external field, and also leads to a new low-frequency oscillation branch. Movement of particles in the HF field gives spatial dispersion. If the frequency of the field exceeds the election Langmuir frequency, the plasma oscillations are stable. At frequencies less than this level there occurs a build-up of low-frequency oscillations. Here the maximum of the build-up occurs when the external field frequencies approach the electron Langmuir frequency and is equal to the product of the Langmuir frequency and the one-third power of the electron-ion mass ratio. Away from the resonance, -the increment of build-up has the same order of magnitude as the ion Langmuir frequency. An external magnetic field increases the number of possible natural plasma oscillations and thereby increases the possibility of resonance with the external HF field. Allowance for the thermal motion of the particles enables one to determine the attenuation of the oscillations in question. Expressions for the decrements are derived. The effect of the external HF field on a plasma in which there are beams is also discussed. An HF field has a destabilizing effect on a system of this kind, since on the one hand there can be a build-up of fresh, low
LENUS (Irish Health Repository)
O’Connell, Emer
2016-07-01
Patient safety requires optimal management of medications. Electronic systems are encouraged to reduce medication errors. Near field communications (NFC) is an emerging technology that may be used to develop novel medication management systems.
Pair production by a constant external field in noncommutative QED
International Nuclear Information System (INIS)
Chair, N.; Sheikh-Jabbari, M.M.
2000-09-01
In this paper we study QED on the noncommutative space in the constant electro-magnetic field background. Using the explicit solutions of the noncommutative version of Dirac equation in such background, we show that there are well-defined in and out-going asymptotic states and also there is a causal Green's function. We calculate the pair production rate in this case. We show that at tree level noncommutativity will not change the pair production and the threshold electric field. We also calculate the pair production rate considering the first loop corrections. In this case we show that the threshold electric field is decreased by the noncommutativity effects. (author)
Effect of Numerical Error on Gravity Field Estimation for GRACE and Future Gravity Missions
McCullough, Christopher; Bettadpur, Srinivas
2015-04-01
In recent decades, gravity field determination from low Earth orbiting satellites, such as the Gravity Recovery and Climate Experiment (GRACE), has become increasingly more effective due to the incorporation of high accuracy measurement devices. Since instrumentation quality will only increase in the near future and the gravity field determination process is computationally and numerically intensive, numerical error from the use of double precision arithmetic will eventually become a prominent error source. While using double-extended or quadruple precision arithmetic will reduce these errors, the numerical limitations of current orbit determination algorithms and processes must be accurately identified and quantified in order to adequately inform the science data processing techniques of future gravity missions. The most obvious numerical limitation in the orbit determination process is evident in the comparison of measured observables with computed values, derived from mathematical models relating the satellites' numerically integrated state to the observable. Significant error in the computed trajectory will corrupt this comparison and induce error in the least squares solution of the gravitational field. In addition, errors in the numerically computed trajectory propagate into the evaluation of the mathematical measurement model's partial derivatives. These errors amalgamate in turn with numerical error from the computation of the state transition matrix, computed using the variational equations of motion, in the least squares mapping matrix. Finally, the solution of the linearized least squares system, computed using a QR factorization, is also susceptible to numerical error. Certain interesting combinations of each of these numerical errors are examined in the framework of GRACE gravity field determination to analyze and quantify their effects on gravity field recovery.
International Nuclear Information System (INIS)
Zhang Fen; Ding Huan-Da; Duan Chao; Tong Chao-Hui; Zhao Shuang-Liang
2017-01-01
Langevin dynamics simulations have been performed to investigate the response of bi-disperse and strong polyacid chains grafted on an electrode to electric fields generated by opposite surface charges on the polyelectrolyte (PE)-grafted electrode and a second parallel electrode. Simulation results clearly show that, under a negative external electric field, the longer grafted PE chains are more strongly stretched than the shorter ones in terms of the relative change in their respective brush heights. Whereas under a positive external electric field, the grafted shorter chains collapse more significantly than the longer ones. It was found that, under a positive external electric field, the magnitude of the total electric force acting on one shorter PE chain is larger than that on one longer PE chain, or vice versa. The effects of smeared and discrete charge distributions of grafted PE chains on the response of PE brushes to external electric fields were also examined. (paper)
Dipole nano-laser: the effect of an external electric field
Energy Technology Data Exchange (ETDEWEB)
Ghannam, T, E-mail: gtalal@hotmail.co [KAIN Institute for Nano-Technology, King Saud University, PO Box 2454, Riyadh 11451 (Saudi Arabia)
2010-08-14
Using the Langevin formalism we study the effects an external electromagnetic field induces in a system made of a pumped two-level system (TLS) and a metallic nano-particle (NP) that interact together via their near-fields. The surface plasmons of the NP greatly enhance the scattered light. With the absence of the external EM field the spectral width of the scattered light is broader than that of the system, covering almost the entire optical range. However, with the inclusion the external EM field, a reduction in the spectral width of the scattered light of order of 10-50 times below that of the system is observed for certain parameter regimes.This system exhibits also bistability in the population difference of the TLS with the external field acting as an order parameter, but only for certain values of the noise quanta.
Effect of external magnetic field on locking range of spintronic feedback nano oscillator
Directory of Open Access Journals (Sweden)
Hanuman Singh
2018-05-01
Full Text Available In this work we have studied the effect of external applied magnetic field on the locking range of spintronic feedback nano oscillator. Injection locking of spintronic feedback nano oscillator at integer and fractional multiple of its auto oscillation frequency was demonstrated recently. Here we show that the locking range increases with increasing external magnetic field. We also show synchronization of spintronic feedback nano oscillator at integer (n=1,2,3 multiples of auto oscillation frequency and side band peaks at higher external magnetic field values. We have verified experimental results with macro-spin simulation using similar conditions as used for the experimental study.
Two-stream instability for a light ion beam-plasma system with external magnetic field
International Nuclear Information System (INIS)
Okada, T.; Tazawa, H.
1992-12-01
For inertial confinement fusion, a focused light ion beam (LIB) is required to propagate stably through a chamber to a target. We have pointed out that the applied external magnetic field is important for LIB propagation. To investigate the influence of the external magnetic field on the LIB propagation, we analysed the electrostatic dispersion relation of magnetized light ion beam-plasma system. The particle in-cell (PIC) simulation results are presented for a light ion beam-plasma system with external magnetic field. (author)
Constant external fields in gauge theory and the spin 0, 1/2, 1 path integrals
International Nuclear Information System (INIS)
Reuter, M.; Schmidt, M.G.
1996-10-01
We investigate the usefulness of the ''string-inspired technique'' for gauge theory calculations in a constant external field background. Our approach is based on Strassler's worldline path integral approach to the Bern-Kosower formalism, and on the construction of worldline (super-) Green's functions incorporating external fields as well as internal propagators. The worldline path integral representation of the gluon loop is reexamined in detail. We calculate the two-loop effective actions induced for a constant external field by a scalar and spinor loop, and the corresponding one-loop effective action in the gluon loop case. (orig.)
Effect of external magnetic field on locking range of spintronic feedback nano oscillator
Singh, Hanuman; Konishi, K.; Bose, A.; Bhuktare, S.; Miwa, S.; Fukushima, A.; Yakushiji, K.; Yuasa, S.; Kubota, H.; Suzuki, Y.; Tulapurkar, A. A.
2018-05-01
In this work we have studied the effect of external applied magnetic field on the locking range of spintronic feedback nano oscillator. Injection locking of spintronic feedback nano oscillator at integer and fractional multiple of its auto oscillation frequency was demonstrated recently. Here we show that the locking range increases with increasing external magnetic field. We also show synchronization of spintronic feedback nano oscillator at integer (n=1,2,3) multiples of auto oscillation frequency and side band peaks at higher external magnetic field values. We have verified experimental results with macro-spin simulation using similar conditions as used for the experimental study.
External field characterization using CHAMP satellite data for ...
Indian Academy of Sciences (India)
The electrical conductivity of the subsurface can be investigated ... the field components have greater power in dusk ... Figure 3. Rotational transformation from GSM to SM frame. ..... second generation of the GFZ reference internal magnetic.
Linear spin-zero quantum fields in external gravitational and scalar fields
International Nuclear Information System (INIS)
Kay, B.S.
1977-10-01
Mathematically rigorous results are given on the quantization of the covariant Klein-Gordon field with an external stationary scalar interaction in a stationary curved space-time. It is shown how, following Segal, Weinless etc., the problem reduces to finding a ''one-particle structure'' for the corresponding classical system. The main result is an existence theorem for such a one-particle structure for a precisely specified class of stationary space-times. Byproducts of our approach are (1)a discussion of when the equal-time hypersurfaces in a given stationary space-time are Cauchy; (2)a proof that when a one-particle structure exists it is unique a result of general interest for the quantization of linear systems; (3)a modification and extension of the methods of Chernoff [3] for proving the essential self-adjointness of ceratin partial differential operators
Linear spin-zero quantum fields in external gravitational and scalar fields
International Nuclear Information System (INIS)
Kay, B.S.
1977-11-01
A general formalism for quantizing the covariant Klein Gordon equation in an arbitrary globally hyperbolic space-time is presented. It is argued that much of the conceptual confusion surrounding ''quantum field theory in curved space-time'' has been caused by the misapplication of a quantization procedure (the single representation formalism) which is really only suitable for quantizing stationary systems. Drawing on a close analogy with time-dependent external field problems in flat space-time, it is argued for the introduction of a new quantization procedure: the many vacuum formalism which accommodates non-stationary situations. In the many vacuum formalism, a whole family of different representations of the field algebra plays a role and dynamics is necessarily described in terms of isomorphisms between different algebras rather than automorphisms of a single algebra. It is shown how this many vacuum approach gives physically sensible results in the flat space-time case. In the curved space-time case, corresponding well defined formalism is obtained relying on rigorous results established in I. A principal feature is that a different vacuum state is obtained for each choice of Cauchy surface together with a choice of lapse and shift functions on that surface. Several questions-mathematical and interpretational- raised by the scheme are discussed
Classical relativistic equations for particles with spin moving in external fields
Dam, H. van; Ruijgrok, Th.W.
1980-01-01
We derive equations of motion for a point particle with spin in an external electromagnetic and in an external scalar field. The derivation is based on the ten conservation laws of linear and angular momentum and on a general expression for the current by which the particle interacts with the
Step-wise potential development across the lipid bilayer under external electric fields
Majhi, Amit Kumar
2018-04-01
Pore formation across the bilayers under external electric field is an important phenomenon, which has numerous applications in biology and bio-engineering fields. However, it is not a ubiquitous event under all field applications. To initiate a pore in the bilayer a particular threshold electric field is required. The electric field alters the intrinsic potential distribution across the bilayer as we as it enhances total potential drop across the bilayer, which causes the pore formation. The intrinsic potential profile has a maximum peak value, which is 0.8 V and it gets enhanced under application of external field, 0.43 V/nm. The peak value becomes 1.4 V when a pore appears in the bilayer and it continues to evolve as along as the external electric field remains switched on.
Effects of an external magnetic field in pulsed laser deposition
García, T.; de Posada, E.; Villagrán, M.; Ll, J. L. Sánchez; Bartolo-Pérez, P.; Peña, J. L.
2008-12-01
Thin films were grown by pulsed laser deposition, PLD, on Si (1 0 0) substrates by the ablation of a sintered ceramic SrFe 12O 19 target with and without the presence of a nonhomogeneous magnetic field of μ0H = 0.4 T perpendicular to substrate plane and parallel to the plasma expansion axis. The field was produced by a rectangular-shaped Nd-Fe-B permanent magnet and the substrate was just placed on the magnet surface (Aurora method). An appreciable increment of optical emission due to the presence of the magnetic field was observed, but no film composition change or thickness increment was obtained. It suggests that the increment of the optical emission is due mainly to the electron confinement rather than confinement of ionic species.
Dirac vacuum: Acceleration and external-field effects
International Nuclear Information System (INIS)
Jauregui, R.; Torres, M.; Hacyan, S.
1991-01-01
The quantization of the massive spin-1/2 field in Rindler coordinates is considered, including the effects of a background magnetic field. We calculate the expectation values of conserved quantities such as the stress-energy tensor, current density, and spin distribution, as detected by an accelerated observer. The ratio of the energy and particle densities is given by a Fermi-Dirac distribution, but the spectrum of these quantities takes in general a complicated form that cannot be simply interpreted as a thermal spectrum. For the free-particle case the spectrum of the energy-stress tensor has a Fermi-Dirac form only in the massless limit. In the presence of the magnetic field the Dirac vacuum is magnetized and exhibits plasmalike properties
Effects of an external magnetic field in pulsed laser deposition
Energy Technology Data Exchange (ETDEWEB)
Garcia, T. [Universidad Autonoma de la Ciudad de Mexico (UACM), Prolongacion San Isidro 151, Col. San Lorenzo Tezonco, C.P. 09790, Mexico DF (Mexico)], E-mail: tupacgarcia@yahoo.com; Posada, E. de [CINVESTAV-IPN Unidad Merida, Applied Physics Department, A.P. 73, Cordemex, C.P. 97130 Merida, Yuc. (Mexico); Villagran, M. [CCADET, Universidad Nacional Autonoma de Mexico (UNAM), A.P. 70-186, C.P. 04510, Mexico DF (Mexico); Ll, J.L. Sanchez [Laboratorio de Magnetismo, Facultad de Fisica-IMRE, Universidad de La Habana, La Habana 10400 (Cuba); Bartolo-Perez, P.; Pena, J.L. [CINVESTAV-IPN Unidad Merida, Applied Physics Department, A.P. 73, Cordemex, C.P. 97130 Merida, Yuc. (Mexico)
2008-12-30
Thin films were grown by pulsed laser deposition, PLD, on Si (1 0 0) substrates by the ablation of a sintered ceramic SrFe{sub 12}O{sub 19} target with and without the presence of a nonhomogeneous magnetic field of {mu}{sub 0}H = 0.4 T perpendicular to substrate plane and parallel to the plasma expansion axis. The field was produced by a rectangular-shaped Nd-Fe-B permanent magnet and the substrate was just placed on the magnet surface (Aurora method). An appreciable increment of optical emission due to the presence of the magnetic field was observed, but no film composition change or thickness increment was obtained. It suggests that the increment of the optical emission is due mainly to the electron confinement rather than confinement of ionic species.
International Nuclear Information System (INIS)
Gavrilov, S.P.; Gitman, D.M.; Fradkin, E.S.
1987-01-01
A generating functional for expectation values is found for QED at a finite temperature with an external field which destroys the stability of the vacuum. The equations for connected Green functions and the effective action for the mean field are written out. Their representation is obtained in the form of an integral over the proper time for the Green function taking into account temperature effects in a constant uniform field. By means of this representation the polarization operator for the mean field in an external constant uniform field has been calculated
International Nuclear Information System (INIS)
Gavrilov, S.P.; Gitman, D.M.; Fradkin, E.S.
1987-01-01
A functional generating expectation values is obtained for QED at a finite temperature in presence of an external field violating the vacuum stability. Equations for connected Green's functions and the effective action for the mean field are derived. The Green function is obtained as an integral with respect of the proper time; the representation takes into account temperature effects in a constant homogeneous field. The polarization operator for the mean field in an external constant homogeneous field is calculated by means of the integral representation
Additional external electromagnetic fields for laser microprocessing of metals.
Schütz, V; Bischoff, K; Brief, S; Koch, J; Suttmann, O; Overmeyer, L
2016-11-14
Ultra-short pulsed laser processing is a potent tool for microstructuring of a lot of materials. At certain laser parameters, particular periodical and/or quasi-periodical µm-size surface structures evolve apparently during processing. With extended plasmonics theory, it is possible to predict the structure formation, and a systematic technology can be derived to alter the surface for laser processing. In this work, we have demonstrated the modification of the laser processing with applying tailored dynamic surface electro-magnetic fields. Possible improvement in applications is seen in the fields of process efficiency of laser ablation and a superior control of the surface topography.
Gauge-independent decoherence models for solids in external fields
Wismer, Michael S.; Yakovlev, Vladislav S.
2018-04-01
We demonstrate gauge-invariant modeling of an open system of electrons in a periodic potential interacting with an optical field. For this purpose, we adapt the covariant derivative to the case of mixed states and put forward a decoherence model that has simple analytical forms in the length and velocity gauges. We demonstrate our methods by calculating harmonic spectra in the strong-field regime and numerically verifying the equivalence of the deterministic master equation to the stochastic Monte Carlo wave-function method.
Periodical plasma structures controlled by external magnetic field
Schweigert, I. V.; Keidar, M.
2017-06-01
The characteristics of two-dimensional periodical structures in a magnetized plasma are studied using kinetic simulations. Ridges (i.e. spikes in electron and ion density) are formed and became more pronounced with an increase of magnetic field incidence angle in the plasma volume in the cylindrical chamber. These ridges are shifted relative to each other, which results in the formation of a two-dimensional double-layer structure. Depending on Larmor radius and Debye length up to 19 potential steps appear across the oblique magnetic field. The electrical current gathered into the channels is associated with the electron and ion density ridges.
Chen, Yue; Cunningham, Gregory; Henderson, Michael
2016-09-01
This study aims to statistically estimate the errors in local magnetic field directions that are derived from electron directional distributions measured by Los Alamos National Laboratory geosynchronous (LANL GEO) satellites. First, by comparing derived and measured magnetic field directions along the GEO orbit to those calculated from three selected empirical global magnetic field models (including a static Olson and Pfitzer 1977 quiet magnetic field model, a simple dynamic Tsyganenko 1989 model, and a sophisticated dynamic Tsyganenko 2001 storm model), it is shown that the errors in both derived and modeled directions are at least comparable. Second, using a newly developed proxy method as well as comparing results from empirical models, we are able to provide for the first time circumstantial evidence showing that derived magnetic field directions should statistically match the real magnetic directions better, with averaged errors ˜ 5°. In addition, our results suggest that the errors in derived magnetic field directions do not depend much on magnetospheric activity, in contrast to the empirical field models. Finally, as applications of the above conclusions, we show examples of electron pitch angle distributions observed by LANL GEO and also take the derived magnetic field directions as the real ones so as to test the performance of empirical field models along the GEO orbits, with results suggesting dependence on solar cycles as well as satellite locations. This study demonstrates the validity and value of the method that infers local magnetic field directions from particle spin-resolved distributions.
Engineering Topological Surface State of Cr-doped Bi2Se3 under external electric field
Zhang, Jian-Min; Lian, Ruqian; Yang, Yanmin; Xu, Guigui; Zhong, Kehua; Huang, Zhigao
2017-03-01
External electric field control of topological surface states (SSs) is significant for the next generation of condensed matter research and topological quantum devices. Here, we present a first-principles study of the SSs in the magnetic topological insulator (MTI) Cr-doped Bi2Se3 under external electric field. The charge transfer, electric potential, band structure and magnetism of the pure and Cr doped Bi2Se3 film have been investigated. It is found that the competition between charge transfer and spin-orbit coupling (SOC) will lead to an electrically tunable band gap in Bi2Se3 film under external electric field. As Cr atom doped, the charge transfer of Bi2Se3 film under external electric field obviously decreases. Remarkably, the band gap of Cr doped Bi2Se3 film can be greatly engineered by the external electric field due to its special band structure. Furthermore, magnetic coupling of Cr-doped Bi2Se3 could be even mediated via the control of electric field. It is demonstrated that external electric field plays an important role on the electronic and magnetic properties of Cr-doped Bi2Se3 film. Our results may promote the development of electronic and spintronic applications of magnetic topological insulator.
Fluctuations in collisional plasma in the presence of an external electric field
International Nuclear Information System (INIS)
Momot, A. I.; Zagorodny, A. G.
2011-01-01
The theory of large-scale fluctuations in a plasma is used to calculate the correlations functions of electron and ion density with regard to particle collisions described within the Bhatnagar-Gross-Krook (BGK) model and the presence of a constant external electric field. The changes of plasma particle distribution functions due to an external electric field and their influence on the plasma dielectric response are taken into account. The dispersion relations for longitudinal waves in such a plasma are studied in details. It is shown that external electric field can lead to the ion-acoustic wave instability and anomalous growth of the fluctuation level. Detailed numerical studies of the general relations for electron number density fluctuations are performed and the effect of external electric field on the fluctuation spectra is studied.
Effect of external electric field on Cyclodextrin-Alcohol adducts: A ...
Indian Academy of Sciences (India)
solid state with organic molecules through host-guest interactions with unique ... for separation of compounds and extraction processes.2. CDs are very attractive ... of external electric field on hydrogen adsorption over activated carbon sepa-.
Conversion of photons into spinless particles in periodic external electromagnetic field
International Nuclear Information System (INIS)
Hoang Ngoc Long; Dang Van Soa
1996-08-01
The conversion of photons into axions and dilatons in a periodic external electromagnetic field, namely in the TE 10 mode, are considered in detail. The differential cross sections are given. (author). 16 refs
Stability properties of a toroidal z-pinch in an external magnetic multipole field
International Nuclear Information System (INIS)
Eriksson, H.G.
1987-01-01
MHD stability of m=1, axisymmetric, external modes of a toroidal z-pinch immersed in an external multipole field (Extrap configuration) is studied. The description includes the effects of a weak toroidicity, a non-circular plasma cross-section and the influence of induced currents in the external conductors. It is found that the non-circularity of the plasma cross-section always has a destabilizing effect but that the m=1 mode can be stabilized by the external feedback if the non-circularity is small. (author)
Energy Technology Data Exchange (ETDEWEB)
Onal, Cem; Dolek, Yemliha; Ozdemir, Yurday [Baskent University, Faculty of Medicine, Adana Dr. Turgut Noyan Research and Treatment Centre, Department of Radiation Oncology, Adana (Turkey)
2017-06-15
To determine whether setup errors during external beam radiation therapy (RT) for prostate cancer are influenced by the combination of androgen deprivation treatment (ADT) and RT. Data from 175 patients treated for prostate cancer were retrospectively analyzed. Treatment was as follows: concurrent ADT plus RT, 33 patients (19%); neoadjuvant and concurrent ADT plus RT, 91 patients (52%); RT only, 51 patients (29%). Required couch shifts without rotations were recorded for each megavoltage (MV) cone beam computed tomography (CBCT) scan, and corresponding alignment shifts were recorded as left-right (x), superior-inferior (y), and anterior-posterior (z). The nonparametric Mann-Whitney test was used to compare shifts by group. Pearson's correlation coefficient was used to measure the correlation of couch shifts between groups. Mean prostate shifts and standard deviations (SD) were calculated and pooled to obtain mean or group systematic error (M), SD of systematic error (Σ), and SD of random error (σ). No significant differences were observed in prostate shifts in any direction between the groups. Shifts on CBCT were all less than setup margins. A significant positive correlation was observed between prostate volume and the z-direction prostate shift (r = 0.19, p = 0.04), regardless of ADT group, but not between volume and x- or y-direction shifts (r = 0.04, p = 0.7; r = 0.03, p = 0.7). Random and systematic errors for all patient cohorts and ADT groups were similar. Hormone therapy given concurrently with RT was not found to significantly impact setup errors. Prostate volume was significantly correlated with shifts in the anterior-posterior direction only. (orig.) [German] Ziel war zu untersuchen, ob Konfigurationsfehler bei der externen Radiotherapie (RT) des Prostatakarzinoms durch die Kombination aus Androgendeprivationstherapie (ADT) und RT beeinflusst werden. Retrospektiv wurden die Daten von 175 wegen eines Prostatakarzinoms behandelten Patienten
External field induced switching of tunneling current in the coupled quantum dots
Mantsevich, V. N.; Maslova, N. S.; Arseyev, P. I.
2014-01-01
We investigated the tunneling current peculiarities in the system of two coupled by means of the external field quantum dots (QDs) weakly connected to the electrodes in the presence of Coulomb correlations. It was found that tuning of the external field frequency induces fast multiple tunneling current switching and leads to the negative tunneling conductivity. Special role of multi-electrons states was demonstrated. Moreover we revealed conditions for bistable behavior of the tunneling curre...
Anisotropic temperature relaxation of plasmas in an external magnetic field
International Nuclear Information System (INIS)
Hassan, M.H.A.
1977-01-01
The magnetized kinetic equation derived in an earlier paper (Hassan and Watson, 1977) is used to study the problem of relaxation of anisotropic electron and ion temperatures in a magnetized plasma. In the case of anisotropic electron temperature relaxation, it is shown that for small anisotropies the exchange of energy within the electrons between the components parallel and perpendicular to the magnetic field direction determine the relaxation rate. For anisotropic ion temperature relaxation it is shown that the essential mechanism for relaxation is provided by energy transfer between ions and electrons, and that the expression for the relaxation rate perpendicular to the magnetic field contains a significant term proportional to ln eta 0 ln (msub(e)/msub(i)) (where eta 0 = Ωsub(e)/ksub(D)Vsub(e perpendicular to)), in addition to the term proportional to the Coulomb logarithm. (author)
Coupled electron/photon transport in static external magnetic fields
International Nuclear Information System (INIS)
Halbleib, J.A. Sr.; Vandevender, W.H.
A model is presented which describes coupled electron/photon transport in the presence of static magnetic fields of arbitrary spatial dependence. The method combines state-of-the-art condensed-history electron collisional Monte Carlo and single-scattering photon Monte Carlo, including electron energy-loss straggling and the production and transport of all generations of secondaries, with numerical field integration via the best available variable-step-size Runge-Kutta-Fehlberg or variable-order/variable-step-size Adams PECE differential equation solvers. A three-dimensional cartesian system is employed in the description of particle trajectories. Although the present model is limited to multilayer material configurations, extension to more complex material geometries should not be difficult. Among the more important options are (1) a feature which permits the neglect of field effects in regions where transport is collision dominated and (2) a method for describing the transport in variable-density media where electron energies and material densities are sufficiently low that the density effect on electronic stopping powers may be neglected. (U.S.)
Numerical simulation of a backward-facing step flow in a microchannel with external electric field
Directory of Open Access Journals (Sweden)
Qing-He Yao
2015-03-01
Full Text Available A backward-facing step flow in the microchannel with external electric field was investigated numerically by a high-order accuracy upwind compact difference scheme in this work. The Poisson–Boltzmann and Navier–Stokes equations were computed by the high-order scheme, and the results confirmed the ability of the new solver in simulation of micro-scale electric double layer effects. The flow fields were displayed for different Reynolds numbers; the positions of the vortex saddle point of model with external electric field and model without external electric field were compared. The average velocity increases linearly with the electric field intensity; however, the Joule heating effects cannot be neglected when the electric field intensity increases to a certain level.
O'Connell, Emer; Pegler, Joe; Lehane, Elaine; Livingstone, Vicki; McCarthy, Nora; Sahm, Laura J; Tabirca, Sabin; O'Driscoll, Aoife; Corrigan, Mark
2016-01-01
Patient safety requires optimal management of medications. Electronic systems are encouraged to reduce medication errors. Near field communications (NFC) is an emerging technology that may be used to develop novel medication management systems. An NFC-based system was designed to facilitate prescribing, administration and review of medications commonly used on surgical wards. Final year medical, nursing, and pharmacy students were recruited to test the electronic system in a cross-over observational setting on a simulated ward. Medication errors were compared against errors recorded using a paper-based system. A significant difference in the commission of medication errors was seen when NFC and paper-based medication systems were compared. Paper use resulted in a mean of 4.09 errors per prescribing round while NFC prescribing resulted in a mean of 0.22 errors per simulated prescribing round (P=0.000). Likewise, medication administration errors were reduced from a mean of 2.30 per drug round with a Paper system to a mean of 0.80 errors per round using NFC (PNFC based medication system may be used to effectively reduce medication errors in a simulated ward environment.
Bifurcated states of a rotating tokamak plasma in the presence of a static error-field
International Nuclear Information System (INIS)
Fitzpatrick, R.
1998-01-01
The bifurcated states of a rotating tokamak plasma in the presence of a static, resonant, error-field are strongly analogous to the bifurcated states of a conventional induction motor. The two plasma states are the open-quotes unreconnectedclose quotes state, in which the plasma rotates and error-field-driven magnetic reconnection is suppressed, and the open-quotes fully reconnectedclose quotes state, in which the plasma rotation at the rational surface is arrested and driven magnetic reconnection proceeds without hindrance. The response regime of a rotating tokamak plasma in the vicinity of the rational surface to a static, resonant, error-field is determined by three parameters: the normalized plasma viscosity, P, the normalized plasma rotation, Q 0 , and the normalized plasma resistivity, R. There are 11 distinguishable response regimes. The extents of these regimes are calculated in P endash Q 0 endash R space. In addition, an expression for the critical error-field amplitude required to trigger a bifurcation from the open-quotes unreconnectedclose quotes to the open-quotes fully reconnectedclose quotes state is obtained in each regime. The appropriate response regime for low-density, ohmically heated, tokamak plasmas is found to be the nonlinear constant-ψ regime for small tokamaks, and the linear constant-ψ regime for large tokamaks. The critical error-field amplitude required to trigger error-field-driven magnetic reconnection in such plasmas is a rapidly decreasing function of machine size, indicating that particular care may be needed to be taken to reduce resonant error-fields in a reactor-sized tokamak. copyright 1998 American Institute of Physics
Polyakov loop fluctuations in the presence of external fields
Lo, Pok Man; Szymański, Michał; Redlich, Krzysztof; Sasaki, Chihiro
2018-06-01
We study the implications of the spontaneous and explicit Z(3) center symmetry breaking for the Polyakov loop susceptibilities. To this end, ratios of the susceptibilities of the real and imaginary parts, as well as of the modulus of the Polyakov loop are computed within an effective model using a color group integration scheme. We show that the essential features of the lattice QCD results of these ratios can be successfully captured by the effective approach. Furthermore we discuss a novel scaling relation in one of these ratios involving the explicit breaking field, volume, and temperature.
κ-deformed Dirac oscillator in an external magnetic field
Chargui, Y.; Dhahbi, A.; Cherif, B.
2018-04-01
We study the solutions of the (2 + 1)-dimensional κ-deformed Dirac oscillator in the presence of a constant transverse magnetic field. We demonstrate how the deformation parameter affects the energy eigenvalues of the system and the corresponding eigenfunctions. Our findings suggest that this system could be used to detect experimentally the effect of the deformation. We also show that the hidden supersymmetry of the non-deformed system reduces to a hidden pseudo-supersymmetry having the same algebraic structure as a result of the κ-deformation.
Properties of color-flavor locked strange quark matter in an external strong magnetic field
Institute of Scientific and Technical Information of China (English)
崔帅帅; 彭光雄; 陆振烟; 彭程; 徐建峰
2015-01-01
The properties of color-flavor locked strange quark matter in an external strong magnetic field are investigated in a quark model with density-dependent quark masses. Parameters are determined by stability arguments. It is found that the minimum energy per baryon of the color-flavor locked (MCFL) matter decreases with increasing magnetic-field strength in a certain range, which makes MCFL matter more stable than other phases within a proper magnitude of the external magnetic field. However, if the energy of the field itself is added, the total energy per baryon will increase.
Particle-in-cell simulations of plasma opening switch with external magnetic field
International Nuclear Information System (INIS)
Chen Yulan; Zeng Zhengzhong; Sun Fengju
2003-01-01
Fully electromagnetic particle-in-cell simulations are performed to study the effects of an external magnetic field on coaxial plasma opening switch (POS). The simulation results show that POS opening performance can be significantly improved only when external longitudinal magnetic field coils are placed at the cathode side, and an additional azimuthal magnetic field is effective whether the central electrode is of positive or negative polarity. Voltage multiplication coefficient K rises with the additional magnetic field increasing till the electron current is completely magnetically insulated during the opening of POS
Earth's external magnetic fields at low orbital altitudes
Klumpar, D. M.
1990-01-01
Under our Jun. 1987 proposal, Magnetic Signatures of Near-Earth Distributed Currents, we proposed to render operational a modeling procedure that had been previously developed to compute the magnetic effects of distributed currents flowing in the magnetosphere-ionosphere system. After adaptation of the software to our computing environment we would apply the model to low altitude satellite orbits and would utilize the MAGSAT data suite to guide the analysis. During the first year, basic computer codes to run model systems of Birkeland and ionospheric currents and several graphical output routines were made operational on a VAX 780 in our research facility. Software performance was evaluated using an input matchstick ionospheric current array, field aligned currents were calculated and magnetic perturbations along hypothetical satellite orbits were calculated. The basic operation of the model was verified. Software routines to analyze and display MAGSAT satellite data in terms of deviations with respect to the earth's internal field were also made operational during the first year effort. The complete set of MAGSAT data to be used for evaluation of the models was received at the end of the first year. A detailed annual report in May 1989 described these first year activities completely. That first annual report is included by reference in this final report. This document summarizes our additional activities during the second year of effort and describes the modeling software, its operation, and includes as an attachment the deliverable computer software specified under the contract.
Control strategies for active noise barriers using near-field error sensing
Berkhoff, Arthur P.
In this paper active noise control strategies for noise barriers are presented which are based on the use of sensors near the noise barrier. Virtual error signals are derived from these near-field sensor signals such that reductions of the far-field sound pressure are obtained with the active
International Nuclear Information System (INIS)
Matyushevskij, E.A.; Morozov, N.A.; Syresin, E.M.
2005-01-01
At the Joint Institute for Nuclear Research (Dubna) the electromagnetic undulator with maximal magnetic field 1.2 T and 40 cm period is under development. The computer models for the undulator magnet system were realized on the basis of POISSON and RADIA codes. The undulator magnetic field imperfections due to the design errors were simulated by the models
Electromagnetic torque on the toroidal plasma and the error-field induced torque
International Nuclear Information System (INIS)
Pustovitov, V. D.
2007-01-01
The electromagnetic torque on the toroidal plasma is calculated assuming a linear plasma response to the applied perturbation, which may be the error field or the field created by the correction coils, or both. The result is compared with recently published expressions for the error field induced torque (Zheng et al 2006 Nucl. Fusion 46 L9, Zheng and Kotschenreuther 2006 Phys. Rev. Lett. 97 165001), and the conclusions of these papers are revised. We resolve the problem of the torque resonance raised there. It is shown that the strong increase in the torque due to the static error field must occur at the resistive wall mode stability limit and not at the no-wall stability limit
SIMULATION OF SYNCHRONIZATION OF NONLINEAR OSCILLATORS BY THE EXTERNAL FIELD
Directory of Open Access Journals (Sweden)
V. M. Kuklin
2017-05-01
Full Text Available In this paper, the self-consistent model was considered, consisting of a system of oscillators, the coupling between them was assumed to be integral (due to the fields formed as a result of their co-radiation. With the help of this model, the features of synchronization by waves of finite amplitude of a system of oscillators were refined, the initial phase values of which are random. The effect of nonlinearity, in particular, due to the change in the mass of the oscillator due to relativistic effects, was taken into account. It was shown that the nonlinearity does not violate the nature of the energy exchange between the wave and the oscillator system, leading only to a slight decrease in the efficiency of such an exchange.
Moving antiphase boundaries using an external electric field
Energy Technology Data Exchange (ETDEWEB)
Vaideeswaran, Kaushik, E-mail: kaushik.vaideeswaran@alumni.epfl.ch; Shapovalov, Konstantin; Yudin, Petr V.; Setter, Nava [Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne (Switzerland); Tagantsev, Alexander K. [Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne (Switzerland); Ferroics Laboratory, Ioffe Physical Technical Institute, 194021 St. Petersburg (Russian Federation)
2015-11-09
Antiphase boundaries (APBs) are unique domain walls that may demonstrate switchable polarization in otherwise non-ferroelectric materials such as SrTiO{sub 3} and PbZrO{sub 3}. The current study explores the possibility of displacing such domain walls at the nanoscale. We suggest the possibility of manipulating APBs using the inhomogeneous electric field of an Atomic Force Microscopy (AFM) tip with an applied voltage placed in their proximity. The displacement is studied as a function of applied voltage, film thickness, and initial separation of the AFM tip from the APB. It is established, for example, that for films with thickness of 15 nm, an APB may be attracted under the tip with a voltage of 25 V from initial separation of 30 nm. We have also demonstrated that the displacement is appreciably retained after the voltage is removed, rendering it favorable for potential applications.
Phase-Field simulation of phase decomposition in Fe-Cr-Co alloy under an external magnetic field
Koyama, Toshiyuki; Onodera, Hidehiro
2004-07-01
Phase decomposition during isothermal aging of a Fe-Cr-Co ternary alloy under an external magnetic field is simulated based on the phase-field method. In this simulation, since the Gibbs energy available from the thermodynamic CALPHAD database of the equilibrium phase diagram is employed as a chemical free energy, the present calculation provides the quantitative microstructure changes directly linked to the phase diagram. The simulated microstructure evolution demonstrates that the lamella like microstructure elongated along the external magnetic field is evolved with the progress of aging. The morphological and temporal developments of the simulated microstructures are in good agreement with experimental results that have been obtained for this alloy system.
Radiation effects on relativistic electrons in strong external fields
International Nuclear Information System (INIS)
Iqbal, Khalid
2013-01-01
The effects of radiation of high energy electron beams are a major issue in almost all types of charged particle accelerators. The objective of this thesis is both the analytical and numerical study of radiation effects. Due to its many applications the study of the self force has become a very active and productive field of research. The main part of this thesis is devoted to the study of radiation effects in laser-based plasma accelerators. Analytical models predict the existence of radiation effects. The investigation of radiation reaction show that in laser-based plasma accelerators, the self force effects lower the energy gain and emittance for moderate energies electron beams and increase the relative energy spread. However, for relatively high energy electron beams, the self radiation and retardation (radiation effects of one electron on the other electron of the system) effects increase the transverse emittance of the beam. The energy gain decreases to even lower value and relative energy spread increases to even higher value due to high radiation losses. The second part of this thesis investigates with radiation reaction in focused laser beams. Radiation effects are very weak even for high energy electrons. The radiation-free acceleration and the simple practical setup make direct acceleration in a focused laser beam very attractive. The results presented in this thesis can be helpful for the optimization of future electron acceleration experiments, in particular in the case of laser-plasma accelerators.
Green functions for an electron in an external electromagnetic field
International Nuclear Information System (INIS)
Khokhlov, I.A.
1982-01-01
New representations permitting to considerably simplify their calculation have been obtained for the Green functions of electron. These representations are based on an idea, used in the quantum electrodynamics formulation in variables of a zero plane, of writing down the Dirac field operator psi through its part psisub((-)). It is shown that T product of psi and psi + operators can be expressed through T product of their parts psisub((-)) and psisub((-))sup(+). At that, if the anticommutator of the operators psisub((-)) and psisub((-))sup(+) satisfies the initial condition, the operations of the chronological ordering of the operator product psi(-) and psisub((-))sup(+) with respect to variable x 0 and variable u 0 playing a part of time in the formulation of the zero plane (Pu 0 product) coincide. In correspondence with this fact all the Green functions of electron can be expressed depending on the convenience of concrete calculations through vacuum averages of either from T product or from Pu 0 product of psisub((-)) and psisub((-))sup(+) operators only [ru
Plasma oscillations in a stationary external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Ciulli, S [Joint Institute for Nuclear Research, Dubna, Moscow (USSR); Micu, M [Institute of Atomic Physics, Bucharest (Romania)
1958-07-01
The stationary distribution function as well as the small deviations from the stationary state of a gas discharge using the Boltzmann equation is studied as a basis for the calculations. The stationary problem which is discussed corresponds to plasma with cylindrical symmetry. It leads to a Maxwell velocity distribution and to a spatial distribution function which has the asymptotic form 1/r{sup 4}. The plasma perturbations are estimated by the deviations of the first order moments from their Maxwell values. A homogeneous system of differential equations is derived for the Fourier amplitudes of the magnetic field and their asymptotic form is studied. The dispersion relation is obtained by joining smoothly a solution regular at the origin with the regular asymptotic one.A number of idealizations and approximations have been made in the present analysis which limit the utility of the formulae obtained. For example, if the collision term is included in the Boltzmann equation additional quantities appear in the final results, i.e., viscosity, thermal and electrical conductivity, etc. Furthermore, the finite dimensions of linear discharge tubes or the toroidal form of some discharges strongly modify the present results. Taking into account these additional effects, exact solutions are to be obtained numerically for different values of the experimental parameters.
International Nuclear Information System (INIS)
Shapiro, B.Y.
1992-01-01
The behavior of a superconductor in time-independent electric field perpendicular to the surface and in the external electromagnetic wave is theoretically investigated. A new type of the resonance interaction between superconducting domains localized along the magnetic field (if the superconducting phase transition takes place in the external magnetic field perpendicular to the surface) and electromagnetic waves is predicted. The surface impedance of the superconductor with domains is calculated. It is shown that the real part of the impedance has a saturation if the skin length equals the domain size. (orig.)
Controlling three-dimensional vortices using multiple and moving external fields
Das, Nirmali Prabha; Dutta, Sumana
2017-08-01
Spirals or scroll wave activities in cardiac tissues are the cause of lethal arrhythmias. The external control of these waves is thus of prime interest to scientists and physicians. In this article, we demonstrate the spatial control of scroll waves by using external electric fields and thermal gradients in experiments with the Belousov-Zhabotinsky reaction. We show that a scroll ring can be made to trace cyclic trajectories under a rotating electric field. Application of a thermal gradient in addition to the electric field deflects the motion and changes the nature of the trajectory. Our experimental results are analyzed and corroborated by numerical simulations based on an excitable reaction diffusion model.
Owens, Alec; Yachmenev, Andrey
2018-03-01
In this paper, a general variational approach for computing the rovibrational dynamics of polyatomic molecules in the presence of external electric fields is presented. Highly accurate, full-dimensional variational calculations provide a basis of field-free rovibrational states for evaluating the rovibrational matrix elements of high-rank Cartesian tensor operators and for solving the time-dependent Schrödinger equation. The effect of the external electric field is treated as a multipole moment expansion truncated at the second hyperpolarizability interaction term. Our fully numerical and computationally efficient method has been implemented in a new program, RichMol, which can simulate the effects of multiple external fields of arbitrary strength, polarization, pulse shape, and duration. Illustrative calculations of two-color orientation and rotational excitation with an optical centrifuge of NH3 are discussed.
Hubbard pair cluster in the external fields. Studies of the magnetic properties
Balcerzak, T.; Szałowski, K.
2018-06-01
The magnetic properties of the two-site Hubbard cluster (dimer or pair), embedded in the external electric and magnetic fields and treated as the open system, are studied by means of the exact diagonalization of the Hamiltonian. The formalism of the grand canonical ensemble is adopted. The phase diagrams, on-site magnetizations, spin-spin correlations, mean occupation numbers and hopping energy are investigated and illustrated in figures. An influence of temperature, mean electron concentration, Coulomb U parameter and external fields on the quantities of interest is presented and discussed. In particular, the anomalous behaviour of the magnetization and correlation function vs. temperature near the critical magnetic field is found. Also, the effect of magnetization switching by the external fields is demonstrated.
Quantum effects in external fields determined by potentials with point-like support
International Nuclear Information System (INIS)
Mamev, S.G.; Trunov, N.N.
1982-01-01
Exact expressions are obtained for the vacuum expectation values of the energy-momentum tensor of a scalar field in external potentials of the delta-function type. The conditions for the onset of the vacuum instability are found and the properties of the resulting condensate are studied. Particle production in the field of a nonstationary delta potential is studied
Processes of arbitrary order in quantum electrodynamics with a pair-creating external field
International Nuclear Information System (INIS)
Gitman, D.M.
1977-01-01
Dyson's perturbation theory analogue for quantum electrodynamical processes with arbitrary initial and final states in an external field creating pairs is discussed. The interaction with the field is taken into account exactly. The possibility of using Feynman diagrams, together with modified correspondence rules, for the representation of the above mentioned processes is demonstrated. (author)
Analysis on optical heterodyne frequency error of full-field heterodyne interferometer
Li, Yang; Zhang, Wenxi; Wu, Zhou; Lv, Xiaoyu; Kong, Xinxin; Guo, Xiaoli
2017-06-01
The full-field heterodyne interferometric measurement technology is beginning better applied by employing low frequency heterodyne acousto-optical modulators instead of complex electro-mechanical scanning devices. The optical element surface could be directly acquired by synchronously detecting the received signal phases of each pixel, because standard matrix detector as CCD and CMOS cameras could be used in heterodyne interferometer. Instead of the traditional four-step phase shifting phase calculating, Fourier spectral analysis method is used for phase extracting which brings lower sensitivity to sources of uncertainty and higher measurement accuracy. In this paper, two types of full-field heterodyne interferometer are described whose advantages and disadvantages are also specified. Heterodyne interferometer has to combine two different frequency beams to produce interference, which brings a variety of optical heterodyne frequency errors. Frequency mixing error and beat frequency error are two different kinds of inescapable heterodyne frequency errors. In this paper, the effects of frequency mixing error to surface measurement are derived. The relationship between the phase extraction accuracy and the errors are calculated. :: The tolerance of the extinction ratio of polarization splitting prism and the signal-to-noise ratio of stray light is given. The error of phase extraction by Fourier analysis that caused by beat frequency shifting is derived and calculated. We also propose an improved phase extraction method based on spectrum correction. An amplitude ratio spectrum correction algorithm with using Hanning window is used to correct the heterodyne signal phase extraction. The simulation results show that this method can effectively suppress the degradation of phase extracting caused by beat frequency error and reduce the measurement uncertainty of full-field heterodyne interferometer.
International Nuclear Information System (INIS)
Goncalves, Bruno; Dias Junior, Mario Marcio
2013-01-01
Full text: The discussion of experimental manifestations of torsion at low energies is mainly related to the torsion-spin interaction. In this respect the behavior of Dirac field and the spinning particle in an external torsion field deserves and received very special attention. In this work, we consider the combined action of torsion and magnetic field on the massive spinor field. In this case, the Dirac equation is not straightforward solved. We suppose that the spinor has two components. The equations have mixed terms between the two components. The electromagnetic field is introduced in the action by the usual gauge transformation. The torsion field is described by the field S μ . The main purpose of the work is to get an explicit form to the equation of motion that shows the possible interactions between the external fields and the spinor in a Hamiltonian that is independent to each component. We consider that S 0 is constant and is the unique non-vanishing term of S μ . This simplification is taken just to simplify the algebra, as our main point is not to describe the torsion field itself. In order to get physical analysis of the problem, we consider the non-relativistic approximation. The final result is a Hamiltonian that describes a half spin field in the presence of electromagnetic and torsion external fields. (author)
Lopsidedness of Self-consistent Galaxies Caused by the External Field Effect of Clusters
Energy Technology Data Exchange (ETDEWEB)
Wu, Xufen [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, 230026 (China); Wang, Yougang [Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Feix, Martin [CNRS, UMR 7095 and UPMC, Institut d’Astrophysique de Paris, 98 bis Boulevard Arago, F-75014 Paris (France); Zhao, HongSheng, E-mail: xufenwu@ustc.edu.cn [School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS (United Kingdom)
2017-08-01
Adopting Schwarzschild’s orbit-superposition technique, we construct a series of self-consistent galaxy models, embedded in the external field of galaxy clusters in the framework of Milgrom’s MOdified Newtonian Dynamics (MOND). These models represent relatively massive ellipticals with a Hernquist radial profile at various distances from the cluster center. Using N -body simulations, we perform a first analysis of these models and their evolution. We find that self-gravitating axisymmetric density models, even under a weak external field, lose their symmetry by instability and generally evolve to triaxial configurations. A kinematic analysis suggests that the instability originates from both box and nonclassified orbits with low angular momentum. We also consider a self-consistent isolated system that is then placed in a strong external field and allowed to evolve freely. This model, just like the corresponding equilibrium model in the same external field, eventually settles to a triaxial equilibrium as well, but has a higher velocity radial anisotropy and is rounder. The presence of an external field in the MOND universe generically predicts some lopsidedness of galaxy shapes.
Lopsidedness of Self-consistent Galaxies Caused by the External Field Effect of Clusters
Wu, Xufen; Wang, Yougang; Feix, Martin; Zhao, HongSheng
2017-08-01
Adopting Schwarzschild’s orbit-superposition technique, we construct a series of self-consistent galaxy models, embedded in the external field of galaxy clusters in the framework of Milgrom’s MOdified Newtonian Dynamics (MOND). These models represent relatively massive ellipticals with a Hernquist radial profile at various distances from the cluster center. Using N-body simulations, we perform a first analysis of these models and their evolution. We find that self-gravitating axisymmetric density models, even under a weak external field, lose their symmetry by instability and generally evolve to triaxial configurations. A kinematic analysis suggests that the instability originates from both box and nonclassified orbits with low angular momentum. We also consider a self-consistent isolated system that is then placed in a strong external field and allowed to evolve freely. This model, just like the corresponding equilibrium model in the same external field, eventually settles to a triaxial equilibrium as well, but has a higher velocity radial anisotropy and is rounder. The presence of an external field in the MOND universe generically predicts some lopsidedness of galaxy shapes.
Externally controlled local magnetic field in a conducting mesoscopic ring coupled to a quantum wire
International Nuclear Information System (INIS)
Maiti, Santanu K.
2015-01-01
In the present work, the possibility of regulating local magnetic field in a quantum ring is investigated theoretically. The ring is coupled to a quantum wire and subjected to an in-plane electric field. Under a finite bias voltage across the wire a net circulating current is established in the ring which produces a strong magnetic field at its centre. This magnetic field can be tuned externally in a wide range by regulating the in-plane electric field, and thus, our present system can be utilized to control magnetic field at a specific region. The feasibility of this quantum system in designing spin-based quantum devices is also analyzed
Dettmer, Jan; Dosso, Stan E
2012-10-01
This paper develops a trans-dimensional approach to matched-field geoacoustic inversion, including interacting Markov chains to improve efficiency and an autoregressive model to account for correlated errors. The trans-dimensional approach and hierarchical seabed model allows inversion without assuming any particular parametrization by relaxing model specification to a range of plausible seabed models (e.g., in this case, the number of sediment layers is an unknown parameter). Data errors are addressed by sampling statistical error-distribution parameters, including correlated errors (covariance), by applying a hierarchical autoregressive error model. The well-known difficulty of low acceptance rates for trans-dimensional jumps is addressed with interacting Markov chains, resulting in a substantial increase in efficiency. The trans-dimensional seabed model and the hierarchical error model relax the degree of prior assumptions required in the inversion, resulting in substantially improved (more realistic) uncertainty estimates and a more automated algorithm. In particular, the approach gives seabed parameter uncertainty estimates that account for uncertainty due to prior model choice (layering and data error statistics). The approach is applied to data measured on a vertical array in the Mediterranean Sea.
Energy-momentum tensor of intermediate vector bosons in an external electromagnetic field
International Nuclear Information System (INIS)
Mostepanenko, V.M.; Sokolov, I.Yu.
1988-01-01
Expressions are obtained for the canonical and metric energy-momentum tensors of the vector field of intermediate bosons in an external electromagnetic field. It is shown that in the case of a gyromagnetic ratio not equal to unity the energy-momentum tensor cannot be symmetrized on its indices, and an additional term proportional to the anomalous magnetic moment appears in the conservation laws. A modification of the canonical formalism for scalar and vector fields in an external field is proposed in accordance with which the Hamiltonian density is equal to the 00 component of the energy-momentum tensor. An expression for the energy-momentum tensor of a closed system containing a gauge field of intermediate bosons and an electromagnetic field is obtained
Self-assembly of colloidal bands driven by a periodic external field
Energy Technology Data Exchange (ETDEWEB)
Nunes, André S.; Araújo, Nuno A. M., E-mail: nmaraujo@fc.ul.pt; Telo da Gama, Margarida M. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, P-1749-016 Lisboa, Portugal and Centro de Física Teórica e Computacional, Universidade de Lisboa, P-1749-016 Lisboa (Portugal)
2016-01-21
We study the formation of bands of colloidal particles driven by periodic external fields. Using Brownian dynamics, we determine the dependence of the band width on the strength of the particle interactions and on the intensity and periodicity of the field. We also investigate the switching (field-on) dynamics and the relaxation times as a function of the system parameters. The observed scaling relations were analyzed using a simple dynamic density-functional theory of fluids.
Plasma coating of nanoparticles in the presence of an external electric field
Ebadi, Zahra; Pourali, Nima; Mohammadzadeh, Hosein
2018-04-01
Film deposition onto nanoparticles by low-pressure plasma in the presence of an external electric field is studied numerically. The plasma discharge fluid model along with surface deposition and heating models for nanoparticles, as well as a dynamics model considering the motion of nanoparticles, are employed for this study. The results of the simulation show that applying external field during the process increases the uniformity of the film deposited onto nanoparticles and leads to that nanoparticles grow in a spherical shape. Increase in film uniformity and particles sphericity is related to particle dynamics that is controlled by parameters of the external field like frequency and amplitude. The results of this work can be helpful to produce spherical core-shell nanoparticles in nanomaterial industry.
Shang, Jimin; Pan, Longfei; Wang, Xiaoting; Li, Jingbo; Wei, Zhongming
2018-03-01
Using density functional theory we explore the band structure of bilayer Indium selenide (InSe), and we find that the van der Waals interaction has significant effects on the electric and optical properties. We then explore the tuning electronic properties by different interlayer distances and by an external vertical electric field. Our results demonstrate that the band gaps of bilayer InSe can be continuously tuned by different interlayer coupling. With decreasing interlayer distances, the tunable band gaps of bilayer decrease linearly, owing to the enhancement of the interlayer interaction. Additionally, the band structure of bilayer InSe under external vertical fields is discussed. The presence of a small external electric field can make a new spatial distribution of electron-hole pairs. A well separation based on the electrons and holes, localized in different layers can be obtained using this easy method. These properties of bilayer InSe indicates potential applications in designing new optoelectronic devices.
Influence of Weak External Magnetic Field on Amorphous and Nanocrystalline Fe-based Alloys
Degmová, J.; Sitek, J.
2010-07-01
Nanoperm, Hitperm and Finamet amorphous and nanocrystalline alloys were measured by Mössbauer spectrometry in a weak external magnetic field of 0.5 T. It was shown that the most sensitive parameters of Mössbauer spectra are the intensities of the 2nd and the 5th lines. Rather small changes were observed also in the case of internal magnetic field values. The spectrum of nanocrystalline Nanoperm showed the increase in A23 parameter (ratio of line intensities) from 2.4 to 3.7 and decrease of internal magnetic field from 20 to 19 T for amorphous subspectrum under the influence of magnetic field. Spectrum of nanocrystalline Finemet shown decrease in A23 parameter from 3.5 to 2.6 almost without a change in the internal magnetic field value. In the case of amorphous Nanoperm and Finemet samples, the changes are almost negligible. Hitperm alloy showed the highest sensitivity to the weak magnetic field, when the A23 parameter increased from 0.4 to 2.5 in the external magnetic fields. The A23 parameter of crystalline subspectrum increased from 2.7 to 3.8 and the value of internal magnetic field corresponding to amorphous subspectrum increased from 22 to 24 T. The behavior of nanocrystalline alloys under weak external magnetic field was analyzed within the three-level relaxation model of magnetic dynamics in an assembly of single-domain particles.
Magnetic structures in ultra-thin Holmium films: Influence of external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, L.J. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Mello, V.D. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Anselmo, D.H.A.L. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Vasconcelos, M.S., E-mail: mvasconcelos@ect.ufrn.br [Escola de Ciência e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil)
2015-03-01
We address the magnetic phases in very thin Ho films at the temperature interval between 20 K and 132 K. We show that slab size, surface effects and magnetic field due to spin ordering impact significantly the magnetic phase diagram. Also we report that there is a relevant reduction of the external field strength required to saturate the magnetization and for ultra-thin films the helical state does not form. We explore the specific heat and the susceptibility as auxiliary tools to discuss the nature of the phase transitions, when in the presence of an external magnetic field and temperature effects. The presence of an external field gives rise to the magnetic phase Fan and the spin-slip structures. - Highlights: • We analyze the magnetic phases of very thin Ho films in the temperature interval 20–132 K. • We show that slab size, etc. due to spin ordering may impact the magnetic phase diagram. • All magnetic phase transitions, for strong magnetic fields, are marked by the specific heat. • The presence of an external field gives rise to the magnetic phase Fan and the spin-slip one.
Problems of an external field in non-Abelian gauge theory
International Nuclear Information System (INIS)
Gavrilov, S.P.; Gitman, D.M.
1992-01-01
In the Abelian gauge field theory QED the principal problems connected with an external field are the problems of exact keeping of an external field in a perturbation theory and appearing in this case the peculiarities of the theory such as the instability of the vacuum and so on. There is the problem of an external field introduction or its interpretation side by side with this problem in Non-Abelian gauge theory. The solution of both these problems in Non-Abelian theory can be considered by analogy with QED. In the present paper, the authors discuss on the example of the spontaneously broken SU(2) x U(1) electroweak theory both the problems of an external field introduction and the problem of exact keeping of this field in the perturbation theory. The Langrangian of this theory in covariant gauge is chosen in the BRST invariant form. In spite of concrete character of the theory studied, the method can be extended to any gauge theory
An Analysis of Ripple and Error Fields Induced by a Blanket in the CFETR
Yu, Guanying; Liu, Xufeng; Liu, Songlin
2016-10-01
The Chinese Fusion Engineering Tokamak Reactor (CFETR) is an important intermediate device between ITER and DEMO. The Water Cooled Ceramic Breeder (WCCB) blanket whose structural material is mainly made of Reduced Activation Ferritic/Martensitic (RAFM) steel, is one of the candidate conceptual blanket design. An analysis of ripple and error field induced by RAFM steel in WCCB is evaluated with the method of static magnetic analysis in the ANSYS code. Significant additional magnetic field is produced by blanket and it leads to an increased ripple field. Maximum ripple along the separatrix line reaches 0.53% which is higher than 0.5% of the acceptable design value. Simultaneously, one blanket module is taken out for heating purpose and the resulting error field is calculated to be seriously against the requirement. supported by National Natural Science Foundation of China (No. 11175207) and the National Magnetic Confinement Fusion Program of China (No. 2013GB108004)
Linear and Nonlinear Response of a Rotating Tokamak Plasma to a Resonant Error-Field
Fitzpatrick, Richard
2014-10-01
An in-depth investigation of the effect of a resonant error-field on a rotating, quasi-cylindrical, tokamak plasma is preformed within the context of resistive-MHD theory. General expressions for the response of the plasma at the rational surface to the error-field are derived in both the linear and nonlinear regimes, and the extents of these regimes mapped out in parameter space. Torque-balance equations are also obtained in both regimes. These equations are used to determine the steady-state plasma rotation at the rational surface in the presence of the error-field. It is found that, provided the intrinsic plasma rotation is sufficiently large, the torque-balance equations possess dynamically stable low-rotation and high-rotation solution branches, separated by a forbidden band of dynamically unstable solutions. Moreover, bifurcations between the two stable solution branches are triggered as the amplitude of the error-field is varied. A low- to high-rotation bifurcation is invariably associated with a significant reduction in the width of the magnetic island chain driven at the rational surface, and vice versa. General expressions for the bifurcation thresholds are derived, and their domains of validity mapped out in parameter space. This research was funded by the U.S. Department of Energy under Contract DE-FG02-04ER-54742.
International Nuclear Information System (INIS)
Phillips, Brooke L.; Jiroutek, Michael R.; Tracton, Gregg; Elfervig, Michelle; Muller, Keith E.; Chaney, Edward L.
2002-01-01
Purpose: Computer-assisted methods to analyze electronic portal images for the presence of treatment setup errors should be studied in controlled experiments before use in the clinical setting. Validation experiments using images that contain known errors usually report the smallest errors that can be detected by the image analysis algorithm. This paper offers human error-detection thresholds as one benchmark for evaluating the smallest errors detected by algorithms. Unfortunately, reliable data are lacking describing human performance. The most rigorous benchmarks for human performance are obtained under conditions that favor error detection. To establish such benchmarks, controlled observer studies were carried out to determine the thresholds of detectability for in-plane and out-of-plane translation and rotation setup errors introduced into digitally reconstructed portal radiographs (DRPRs) of prostate fields. Methods and Materials: Seventeen observers comprising radiation oncologists, radiation oncology residents, physicists, and therapy students participated in a two-alternative forced choice experiment involving 378 DRPRs computed using the National Library of Medicine Visible Human data sets. An observer viewed three images at a time displayed on adjacent computer monitors. Each image triplet included a reference digitally reconstructed radiograph displayed on the central monitor and two DRPRs displayed on the flanking monitors. One DRPR was error free. The other DRPR contained a known in-plane or out-of-plane error in the placement of the treatment field over a target region in the pelvis. The range for each type of error was determined from pilot observer studies based on a Probit model for error detection. The smallest errors approached the limit of human visual capability. The observer was told what kind of error was introduced, and was asked to choose the DRPR that contained the error. Observer decisions were recorded and analyzed using repeated
DEFF Research Database (Denmark)
Moretto, T.; Vennerstrøm, Susanne; Olsen, Nils
2006-01-01
simulated external contributions relevant for internal field modeling. These have proven very valuable for the design and planning of the up-coming multi-satellite Swarm mission. In addition, a real event simulation was carried out for a moderately active time interval when observations from the Orsted...... it consistently underestimates the dayside region 2 currents and overestimates the horizontal ionospheric closure currents in the dayside polar cap. Furthermore, with this example we illustrate the great benefit of utilizing the global model for the interpretation of Swarm external field observations and......, likewise, the potential of using Swarm measurements to test and improve the global model....
Tunneling effect of the spin-2 Bose condensate driven by external magnetic fields
International Nuclear Information System (INIS)
Yu Zhaoxian; Jiao Zhiyong
2004-01-01
In this Letter, we have studied tunneling effect of the spin-2 Bose condensate driven by external magnetic field. We find that the population transfers among spin-0 and spin-±1, spin-0 and spin-±2 exhibit the step structure under the external cosinusoidal magnetic field, respectively, but there do not exist step structure among spin-±1 and spin-±2. The tunneling current among spin-±1 and spin-±2 may exhibit periodically oscillation behavior, but among spin-0 and spin-±1, spin-0 and spin-±2, the tunneling currents exhibit irregular oscillation behavior
Tunneling effect of the spin-2 Bose condensate driven by external magnetic fields
Yu, Zhao-xian; Jiao, Zhi-yong
2003-01-01
In this paper, we have studied tunneling effect of the spin-2 Bose condensate driven by external magnetic field. We find that the population transfers among spin-0 and spin-$\\pm1$, spin-0 and spin-$\\pm2$ exhibit the step structure under the external cosinusoidal magnetic field respectively, but there do not exist step structure among spin-$\\pm1$ and spin-$\\pm2$. The tunneling current among spin-$\\pm1$ and spin-$\\pm2$ may exhibit periodically oscillation behavior, but among spin-0 and spin-$\\p...
Energy Technology Data Exchange (ETDEWEB)
Koizumi, H.; Uda, S.; Fujiwara, K.; Nozawa, J. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 (Japan); Tachibana, M. [Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027 (Japan); Kojima, K. [Department of Education, Yokohama Soei University, 1 Miho-tyou, Midori-ku, Yokohama, 226-0015 (Japan)
2014-10-06
X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.
Electronic properties of phosphorene/graphene heterostructures: Effect of external electric field
Energy Technology Data Exchange (ETDEWEB)
Kaur, Sumandeep; Srivastava, Sunita; Tankeshwar, K. [Department of Physics, Panjab University, Chandigarh-160014 (India); Kumar, Ashok [Centre for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India 151001 (India)
2016-05-23
We report the electronic properties of electrically gated heterostructures of black and blue phosphorene with graphene. The heterostructure of blue phosphorene with graphene is energetically more favorable than black phospherene/graphene. However, both are bonded by weak interlayer interactions. Graphene induces the Dirac cone character in both heterostructure which shows tunabilities with external electric field. It is found that Dirac cone get shifted depending on the polarity of external electric field that results into the so called self induced p-type or n-type doping effect. These features have importance in the fabrication of nano-electronic devices based on the phosphorene/graphene heterostructures.
Improvement of the density limit with an external helical field on JFT-2M tokamak
International Nuclear Information System (INIS)
Tamai, H.; Shoji, T.; Nagashima, K.; Miura, Y.; Yamauchi, T.; Ogawa, H.; Kawashima, H.; Matsuda, T.; Mori, M.; Ida, K.; Ohdachi, S.
1995-01-01
The density limit is increased by the application of an external helical field in the JFT-2M tokamak. The effect of the magnetic stochasticity due to the external field is investigated to study the mechanism of the improved density limit related to the edge plasma behaviour. The improvement is correlated with the retardation of the increase in the plasma inductance. At the improved density limit, local radiation loss is modified by the helical field, in which that from the vicinity of separatrix X-point is remarkably reduced, while that from outboard edge is slightly increased. The formation of a positive radial electric field at the plasma edge is also observed in the presence of the helical field. ((orig.))
Deflection modeling of permanent magnet spherical chains in the presence of external magnetic fields
Energy Technology Data Exchange (ETDEWEB)
O' Donoghue, Kilian, E-mail: kilianod@rennes.ucc.ie; Cantillon-Murphy, Pádraig, E-mail: padraig@alum.mit.edu
2013-10-15
This work examines the interaction of permanently magnetised spheres in the presence of external magnetic fields at the millimetre scale. Static chain formation and deflection models are described for N spheres in the presence of an external magnetic field. Analytical models are presented for the two sphere case by neglecting the effects of magnetocrystalline anisotropy while details of a numerical approach to solve a chain of N spheres are shown. The model is experimentally validated using chain deflections in 4.5 mm diameter spheres in groups of 2, 3 and 4 magnets in the presence of uniform magnetic fields, neglecting gravitational effects, with good agreement between the theoretical model and experimental results. This spherical chain structure could be used as an end effector for catheters as a deflection mechanism for magnetic guidance. The spherical point contacts result in large deflections for navigation around tight corners in endoluminal minimally invasive clinical applications. - Highlights: • We model the interaction of magnetic spheres with uniform external fields. • Analytical models are presented for two spheres interacting with an external field. • Numerical methods are used to model the interaction of N spheres in chain formations. • These models are tested experimentally. • We report good agreement between experiment and theory.
Influence of periodic external fields in multiagent models with language dynamics
Palombi, Filippo; Ferriani, Stefano; Toti, Simona
2017-12-01
We investigate large-scale effects induced by external fields, phenomenologically interpreted as mass media, in multiagent models evolving with the microscopic dynamics of the binary naming game. In particular, we show that a single external field, broadcasting information at regular time intervals, can reverse the majority opinion of the population, provided the frequency and the effectiveness of the sent messages lie above well-defined thresholds. We study the phase structure of the model in the mean field approximation and in numerical simulations with several network topologies. We also investigate the influence on the agent dynamics of two competing external fields, periodically broadcasting different messages. In finite regions of the parameter space we observe periodic equilibrium states in which the average opinion densities are reversed with respect to naive expectations. Such equilibria occur in two cases: (i) when the frequencies of the competing messages are different but close to each other; (ii) when the frequencies are equal and the relative time shift of the messages does not exceed half a period. We interpret the observed phenomena as a result of the interplay between the external fields and the internal dynamics of the agents and conclude that, depending on the model parameters, the naming game is consistent with scenarios of first- or second-mover advantage (to borrow an expression from the jargon of business strategy).
The study of the dynamics of erythrocytes under the influence of an external electric field
Mamaeva, Sargylana N.; Maksimov, Georgy V.; Antonov, Stepan R.
2017-11-01
A mathematical model is considered for the determination of the surface charge of an erythrocyte with its shape approximated by a surface of revolution of the second order, and the investigation of the dynamics of erythrocytes under the influence of an external electric field. In the first part of this work, the electrical surface charge of the erythrocyte of the patient was calculated with the assumption that the change in the shape and size of the red blood cells leads to stabilization of the electric field, providing a normal electrostatic repulsion. In the second part of the work, the research results of dynamics of changes in the morphology of erythrocytes under the influence of an external electric field depending on the values of their surface charge and resistance of blood plasma is presented. In the course of the work, the dependence of the surface charge of red blood cells from their shape and size is presented. The determination of the relationship between the value of the charge field and the surface of erythrocytes in norm and in pathology is shown. The dependence of the velocity of the erythrocytes on the characteristics of the external electric field, surface charge of the erythrocyte and properties of the medium is obtained. The results of this study can be applied indirectly to diagnose diseases and to develop recommendations for experimental studies of hemodynamics under the influence of various external physical factors.
International Nuclear Information System (INIS)
Bojko, V.S.; Lazareva, M.B.; Starodubov, Ya.D.; Chernyj, O.V.; Gorbatenko, V.M.
1992-01-01
The effect of external magnetic fields on the stress at which the critical current starts to degrade (the degradation threshold σ 0 e ) under mechanical loads in superconducting Nb-Ti alloys is studied and a possible mechanism of realization of the effect observed is proposed.It is assumed that additional stresses on the transformation dislocation from the external magnetic fields are beneficial for the growth of martensite inclusions whose superconducting parameters (critical current density j k and critical temperature T k ) are lower then those in the initial material.The degradation threshold is studied experimentally in external magnetic fields H up to 7 T.The linear dependence σ 0 e (H) is observed.It is shown that external magnetic fields play an important role in the critical current degradation at the starting stages of deformation.This fact supports the assumption that the degradation of superconducting parameters under loading are due to the phenomenon of superelasticity,i.e. a reversible load-induced change in the martensite inclusions sizes rather than the reversible mechanical twinning.The results obtained are thought to be important to estimating superconducting solenoid stability in a wide range of magnetic fields
Deflection modeling of permanent magnet spherical chains in the presence of external magnetic fields
International Nuclear Information System (INIS)
O'Donoghue, Kilian; Cantillon-Murphy, Pádraig
2013-01-01
This work examines the interaction of permanently magnetised spheres in the presence of external magnetic fields at the millimetre scale. Static chain formation and deflection models are described for N spheres in the presence of an external magnetic field. Analytical models are presented for the two sphere case by neglecting the effects of magnetocrystalline anisotropy while details of a numerical approach to solve a chain of N spheres are shown. The model is experimentally validated using chain deflections in 4.5 mm diameter spheres in groups of 2, 3 and 4 magnets in the presence of uniform magnetic fields, neglecting gravitational effects, with good agreement between the theoretical model and experimental results. This spherical chain structure could be used as an end effector for catheters as a deflection mechanism for magnetic guidance. The spherical point contacts result in large deflections for navigation around tight corners in endoluminal minimally invasive clinical applications. - Highlights: • We model the interaction of magnetic spheres with uniform external fields. • Analytical models are presented for two spheres interacting with an external field. • Numerical methods are used to model the interaction of N spheres in chain formations. • These models are tested experimentally. • We report good agreement between experiment and theory
DEFF Research Database (Denmark)
Olsen, Nils; Sabaka, T.J.; Lowes, F.
2005-01-01
When deriving spherical harmonic models of the Earth's magnetic field, low-degree external field contributions are traditionally considered by assuming that their expansion coefficient q(1)(0) varies linearly with the D-st-index, while induced contributions are considered assuming a constant ratio...... Q(1) of induced to external coefficients. A value of Q(1) = 0.27 was found from Magsat data and has been used by several authors when deriving recent field models from Orsted and CHAMP data. We describe a new approach that considers external and induced field based on a separation of D-st = E-st + I......-st into external (E-st) and induced (I-st) parts using a 1D model of mantle conductivity. The temporal behavior of q(1)(0) and of the corresponding induced coefficient are parameterized by E-st and I-st, respectively. In addition, we account for baseline-instabilities of D-st by estimating a value of q(1...
Effect of manufacturing errors on field quality of the LBL SSC dipoles
International Nuclear Information System (INIS)
Meuser, R.B.
1984-01-01
A method is developed for determining the field aberrations resulting from specific kinds of manufacturing errors. This method is applied to the 40-mm i.d. dipoles under consideration at LBL, and also to similar ones with 30 and 50 mm i.d. The method is also applied to the CBA and Doubler/Saver magnets and the results compared with the measurements. The results obtained by this method are also compared with those obtained by assigning identical errors to the positions of the edges of all the coil sectors
Random errors in the magnetic field coefficients of superconducting quadrupole magnets
International Nuclear Information System (INIS)
Herrera, J.; Hogue, R.; Prodell, A.; Thompson, P.; Wanderer, P.; Willen, E.
1987-01-01
The random multipole errors of superconducting quadrupoles are studied. For analyzing the multipoles which arise due to random variations in the size and locations of the current blocks, a model is outlined which gives the fractional field coefficients from the current distributions. With this approach, based on the symmetries of the quadrupole magnet, estimates are obtained of the random multipole errors for the arc quadrupoles envisioned for the Relativistic Heavy Ion Collider and for a single-layer quadrupole proposed for the Superconducting Super Collider
The effects of field errors on low-gain free-electron lasers
International Nuclear Information System (INIS)
Esarey, E.; Tang, C.M.; Marable, W.P.
1991-01-01
This paper reports on the effects of random wiggler magnetic field errors on low-gain free-electron lasers that are examined analytically and numerically through the use of ensemble averaging techniques. Wiggler field errors perturb the electron beam as it propagates and lead to a random walk of the beam centroid δx, variations in the axial beam energy δ γz and deviations in the relative phase of the electrons in the ponderomotive wave δψ. In principle, the random walk may be kept as small as desired through the use of transverse focusing and beam steering. Transverse focusing of the electron beam is shown to be ineffective in reducing the phase deviation. Furthermore, it is shown that beam steering at the wiggler entrance reduces the average phase deviation at the end of the wiggler by 1/3. The effect of the field errors (via the phase deviation) on the gain in the low-gain regime is calculated. To avoid significant reduction in gain it is necessary for the phase deviation to be small compared to 2π. The detrimental effects of wiggler errors on low-gain free-electron lasers may be reduced by arranging the magnet poles in an optimal ordering such that the magnitude of the phase deviation is minimized
Communication: Polarizable polymer chain under external electric field in a dilute polymer solution.
Budkov, Yu A; Kolesnikov, A L; Kiselev, M G
2015-11-28
We study the conformational behavior of polarizable polymer chain under an external homogeneous electric field within the Flory type self-consistent field theory. We consider the influence of electric field on the polymer coil as well as on the polymer globule. We show that when the polymer chain conformation is a coil, application of external electric field leads to its additional swelling. However, when the polymer conformation is a globule, a sufficiently strong field can induce a globule-coil transition. We show that such "field-induced" globule-coil transition at the sufficiently small monomer polarizabilities goes quite smoothly. On the contrary, when the monomer polarizability exceeds a certain threshold value, the globule-coil transition occurs as a dramatic expansion in the regime of first-order phase transition. The developed theoretical model can be applied to predicting polymer globule density change under external electric field in order to provide more efficient processes of polymer functionalization, such as sorption, dyeing, and chemical modification.
Measurement of tokamak error fields using plasma response and its applicability to ITER
International Nuclear Information System (INIS)
Strait, E.J.; Buttery, R.J.; Chu, M.S.; Garofalo, A.M.; La Haye, R.J.; Schaffer, M.J.; Casper, T.A.; Gribov, Y.; Hanson, J.M.; Reimerdes, H.; Volpe, F.A.
2014-01-01
The nonlinear response of a low-beta tokamak plasma to non-axisymmetric fields offers an alternative to direct measurement of the non-axisymmetric part of the vacuum magnetic fields, often termed ‘error fields’. Possible approaches are discussed for determination of error fields and the required current in non-axisymmetric correction coils, with an emphasis on two relatively new methods: measurement of the torque balance on a saturated magnetic island, and measurement of the braking of plasma rotation in the absence of an island. The former is well suited to ohmically heated discharges, while the latter is more appropriate for discharges with a modest amount of neutral beam heating to drive rotation. Both can potentially provide continuous measurements during a discharge, subject to the limitation of a minimum averaging time. The applicability of these methods to ITER is discussed, and an estimate is made of their uncertainties in light of the specifications of ITER's diagnostic systems. The use of plasma response-based techniques in normal ITER operational scenarios may allow identification of the error field contributions by individual central solenoid coils, but identification of the individual contributions by the outer poloidal field coils or other sources is less likely to be feasible. (paper)
Nonlinear mechanism for the suppression of error field magnetic islands by plasma flow
International Nuclear Information System (INIS)
Parker, R.D.
1992-01-01
Non-axisymmetric magnetic field perturbations generated, for example, by errors in the alignment of the field coils are known to lead to reduced confinement in a tokamak. By inducing the formation of small, stationary, magnetic islands on all rational surfaces they can enhance radial transport and under certain circumstances interact with MHD instabilities to trigger the onset of locked modes leading, in some cases, to disruption of the plasma discharge. Given the stationary nature of the error field islands it is natural to consider whether they can be reduced significantly by the viscous drag of a sheared flow resulting from a bulk rotation of the plasma. In this paper, we examine this interaction by modelling the nonlinear growth and saturation of force-reconnected magnetic islands driven by a corrugated boundary in a slab plasma with an initially uniform flow. A systematic parameter study is made of the time asymptotic steady state. (author) 3 figs., 5 refs
Near-field visualization of plasmonic lenses: an overall analysis of characterization errors
Directory of Open Access Journals (Sweden)
Jing Wang
2015-10-01
Full Text Available Many factors influence the near-field visualization of plasmonic structures that are based on perforated elliptical slits. Here, characterization errors are experimentally analyzed in detail from both fabrication and measurement points of view. Some issues such as geometrical parameter, probe–sample surface interaction, misalignment, stigmation, and internal stress, have influence on the final near-field probing results. In comparison to the theoretical ideal case of near-field probing of the structures, numerical calculation is carried out on the basis of a finite-difference and time-domain (FDTD algorithm so as to support the error analyses. The analyses performed on the basis of both theoretical calculation and experimental probing can provide a helpful reference for the researchers probing their plasmonic structures and nanophotonic devices.
PREFACE: Quantum Field Theory Under the Influence of External Conditions (QFEXT07)
Bordag, M.; Mostepanenko, V. M.
2008-04-01
This special issue contains papers reflecting talks presented at the 8th Workshop on Quantum Field Theory Under the Influence of External Conditions (QFEXT07), held on 17 21 September 2007, at Leipzig University. This workshop gathered 108 physicists and mathematicians working on problems which are focused on the following topics: •Casimir and van der Waals forces—progress in theory and new experiments, applications at micro- and nano-scale •Casimir effect—exact results, approximate methods and mathematical problems •Vacuum quantum effects in classical background fields—renormalization issues, singular backgrounds, applications to particle and high energy physics •Vacuum energy and gravity, vacuum energy in supersymmetric and noncommutative theories. This workshop is part of a series started in 1989 and 1992 in Leipzig by Dieter Robaschik, and continued in 1995, 1998 and 2001 in Leipzig by Michael Bordag. In 2003 this Workshop was organized by Kimball A Milton in Oklahoma, in 2005 by Emilio Elizalde in Barcelona and in 2007 it returned to Leipzig. The field of physics after which this series of workshops is named is remarkably broad. It stretches from experimental work on the measurement of dispersion forces between macroscopic bodies to quantum corrections in the presence of classical background fields. The underlying physical idea is that even in its ground state (vacuum) a quantum system responds to changes in its environment. The universality of this idea makes the field of its application so very broad. The most prominent manifestation of vacuum energy is the Casimir effect. This is, in its original formulation, the attraction between conducting planes due to the vacuum fluctuations of the electromagnetic field. In a sense, this is the long-range tail of the more general dispersion forces acting between macroscopic bodies. With the progress in nanotechnology, dispersion forces become of direct practical significance. On a more theoretical side
Research on the effect of the external magnetic field in the joule balance at NIM
Xu, Jinxin; You, Qiang; Li, Zhengkun; Bai, Yang; Lu, Yunfeng; Zhang, Zhonghua; He, Qing
2018-06-01
The first determination of the Planck constant with the second generation of the joule balance, NIM-2, was completed in 2017 with an uncertainty of 2.4 × 10‑7. Due to the movement of the magnet during the measurement process, the effect of the external field is a critical problem in NIM-2. At present, the electromagnet system is used in NIM-2. By taking the average of the results with positive and negative exciting currents, the uncertainty from the external field is reduced to 1.7 × 10‑7, which is still the largest source in the uncertainty budget as all the other items are less than 1 × 10‑7. In the near future, a permanent magnet system will be applied in NIM-2 and the main field cannot be reversed. Although the coupling of the external magnetic field in the permanent magnet system is about 40 times less than that in the electromagnet system, further reduction of this effect is still required in the permanent magnet system. In this paper, the effect of the external field is analyzed in both an electromagnet system and a permanent magnet system based on simulations and experiments. Then, the methods of magnetic shielding and compensation coils are proposed and simulated in the permanent magnet system. The results show that it may be possible to reduce the uncertainty of the external field to less than 2 × 10‑8 in the permanent magnet system by employing the two methods.
Mars gravity field error analysis from simulated radio tracking of Mars Observer
International Nuclear Information System (INIS)
Smith, D.E.; Lerch, F.J.; Chan, J.C.; Chinn, D.S.; Iz, H.B.; Mallama, A.; Patel, G.B.
1990-01-01
The Mars Observer (MO) Mission, in a near-polar orbit at 360-410 km altitude for nearly a 2-year observing period, will greatly improve our understanding of the geophysics of Mars, including its gravity field. To assess the expected improvement of the gravity field, the authors have conducted an error analysis based upon the mission plan for the Mars Observer radio tracking data from the Deep Space Network. Their results indicate that it should be possible to obtain a high-resolution model (spherical harmonics complete to degree and order 50 corresponding to a 200-km horizontal resolution) for the gravitational field of the planet. This model, in combination with topography from MO altimetry, should provide for an improved determination of the broad scale density structure and stress state of the Martian crust and upper mantle. The mathematical model for the error analysis is based on the representation of doppler tracking data as a function of the Martian gravity field in spherical harmonics, solar radiation pressure, atmospheric drag, angular momentum desaturation residual acceleration (AMDRA) effects, tracking station biases, and the MO orbit parameters. Two approaches are employed. In the first case, the error covariance matrix of the gravity model is estimated including the effects from all the nongravitational parameters (noise-only case). In the second case, the gravity recovery error is computed as above but includes unmodelled systematic effects from atmospheric drag, AMDRA, and solar radiation pressure (biased case). The error spectrum of gravity shows an order of magnitude of improvement over current knowledge based on doppler data precision from a single station of 0.3 mm s -1 noise for 1-min integration intervals during three 60-day periods
The Effect of External Magnetic Field on Dielectric Permeability of Multiphase Ferrofluids
Dotsenko, O. A.; Pavlova, A. A.; Dotsenko, V. S.
2018-03-01
Nowadays, ferrofluids are applied in various fields of science and technology, namely space, medicine, geology, biology, automobile production, etc. In order to investigate the feasibility of applying ferrofluids in magnetic field sensors, the paper presents research into the influence of the external magnetic field on dielectric permeability of ferrofluids comprising magnetite nanopowder, multiwall carbon nanotubes, propanetriol and deionized water. The real and imaginary parts of the dielectric permeability change respectively by 3.7 and 0.5% when applying the magnetic field parallel to the electric. The findings suggest that the considered ferrofluid can be used as a magnetic level gauge or in design of variable capacitors.
Foucault imaging and small-angle electron diffraction in controlled external magnetic fields.
Nakajima, Hiroshi; Kotani, Atsuhiro; Harada, Ken; Ishii, Yui; Mori, Shigeo
2016-12-01
We report a method for acquiring Foucault images and small-angle electron diffraction patterns in external magnetic fields using a conventional transmission electron microscope without any modification. In the electron optical system that we have constructed, external magnetic fields parallel to the optical axis can be controlled using the objective lens pole piece under weak excitation conditions in the Foucault mode and the diffraction mode. We observe two ferromagnetic perovskite-type manganese oxides, La 0.7 Sr 0.3 MnO 3 (LSMO) and Nd 0.5 Sr 0.5 MnO 3 , in order to visualize magnetic domains and their magnetic responses to external magnetic fields. In rhombohedral-structured LSMO, pinning of magnetic domain walls at crystallographic twin boundaries was found to have a strong influence on the generation of new magnetic domains in external applied magnetic fields. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
International Nuclear Information System (INIS)
Dittrich, W.; Bauhoff, W.
1981-01-01
It is re-examined the problem of spontaneous pair creation in an external magnetic field. In contrast to earlier findings, it is shown that pair production does not occur due to the anomalous magnetic moment interaction. However, pairs may be observed in a situation of thermodynamic equilibrium at finite temperatures. (author)
Some remarks on spinor particle pair creation in alternating homogeneous external field
International Nuclear Information System (INIS)
Perelomov, A.M.
1975-01-01
It is shown that the dynamical symmetry group of the problem of spinor particle pair creation in alternating homogeneous external fields is the SO(5) group. The probability of pair creation is given by the modulus square of the matrix element of spinor representation of this group. (Auth.)
Implementability of gauge transformations and quantization of fermions in external fields
International Nuclear Information System (INIS)
Grosse, H.; Karner, G.
1986-01-01
Quantization of fermions in an external soliton field, leading to a representation of the CAR which is inequivalent to the representation connected to the massive Dirac operator, is studied. We determine classes of gauge and axial gauge transformations which can be unitarily implemented. In the latter case quantization conditions for gauge functions are obtained; integers entering can be interpreted as winding numbers. (Author)
DEFF Research Database (Denmark)
Popa, Paula Irina; Pivnenko, Sergey; Breinbjerg, Olav
2015-01-01
,J.M. Nielsen, O. Breinbjerg, 60 GHz Antenna Measurement Setup using a VNA without External Frequency Conversion,36th Annual Symposium of the Antenna Measurement Technique Association ,October 12-17,Tucson, Arizona, 2014]. In this work we extend the validation of this 60 GHz planar near-field (PNF) set...
The effect of internal and external fields of view on visually induced motion sickness
Bos, J.E.; Vries, S.C. de; Emmerik, M.L. van; Groen, E.L.
2010-01-01
Field of view (FOV) is said to affect visually induced motion sickness. FOV, however, is characterized by an internal setting used by the graphics generator (iFOV) and an external factor determined by screen size and viewing distance (eFOV). We hypothesized that especially the incongruence between
Terahertz Solitons in Biomolecular Systems and their Excitation by External Electromagnetic Field
Directory of Open Access Journals (Sweden)
Bugay А.N.
2015-01-01
Full Text Available Nonlinear dynamics of charge and acoustic excitations in cellular microtubules is considered. Different types of nonlinear solitary waves were studied taking account for dissipation. The mechanism of electro-acoustic pulse excitation by external electromagnetic field of terahertz frequency is recognized.
Effect of an External Electric Field on Positronium Formation in Positron Spur
DEFF Research Database (Denmark)
Mogensen, O. E.
1975-01-01
The decrease of positronium (Ps) formation in condensed matter caused by the presence of an external electric field is discussed in terms of the spur reaction model of Ps formation. The rather few experimental results available are shown to be in good agreement with the predictions of the model...
Vacuum energy induced by an external magnetic field in a curved space
International Nuclear Information System (INIS)
Sitenko, Yu.A.; Rakityansky, D.G.
1998-01-01
The asymptotic expansion of the product of an operator raised to an arbitrary power and an exponential function of this operator is obtained. With the aid of this expansion, the density of vacuum energy induced by a static external magnetic field of an Abelian or a non-Abelian nature is expressed in terms of the DeWitt-Seeley-Gilkey coefficients
Increased particle confinement with the use of external dc bias field in the CTX spheromak
International Nuclear Information System (INIS)
Barnes, C.W.; Hoida, H.W.; Henins, I.; Fernandez, J.C.; Jarboe, T.R.; Marklin, G.J.
1985-01-01
Spheromaks are formed in a mesh flux conserver in the presence of an external dc bias field. The spheromaks remain stable to tilt instabilities with ratios of bias-to-spheromak flux of up to 47 +- 7%. Normally applied bias flux puts the spheromak separatrix inside the metal mesh and improves the particle confinement
Basak, Tista; Basak, Tushima
2018-02-01
In this paper, we demonstrate that the optical properties of finite-sized graphene quantum dots can be effectively controlled by doping it with different types of charge carriers (electron/hole). In addition, the role played by a suitably directed external electric field on the optical absorption of charge-doped graphene quantum dots have also been elucidated. The computations have been performed on diamond-shaped graphene quantum dot (DQD) within the framework of the Pariser-Parr-Pople (PPP) model Hamiltonian, which takes into account long-range Coulomb interactions. Our results reveal that the energy band-gap increases when the DQD is doped with holes while it decreases on doping it with electrons. Further, the optical absorption spectra of DQD exhibits red/blue-shift on doping with electrons/holes. Our computations also indicate that the application of external transverse electric field results in a substantial blue-shift of the optical spectrum for charge-doped DQD. However, it is observed that the influence of charge-doping is more prominent in tuning the optical properties of finite-sized graphene quantum dots as compared to externally applied electric field. Thus, tailoring the optical properties of finite-sized graphene quantum dots by manipulative doping with charge carriers and suitably aligned external electric field can greatly enhance its potential application in designing nano-photonic devices.
Nonlinear diffusion in the presence of a time-dependent external electric field
International Nuclear Information System (INIS)
Lima e Silva, T. de; Galvao, R.M.O.
1987-09-01
The influence of a time-dependent external electric field on the nonlinear diffusion process of weakly ionized plasmas is investigated. A new solution of the diffusion equation is obtained for the case when electron-ion collisions can be neglected. (author) [pt
New Cooperative Mechanisms of Low Energy Nuclear Reactions Using Superlow Energy External Fields
Gareev, F. A.; Zhidkova, I. E.
2005-01-01
We proposed a new mechanism of LENR: cooperative processes in whole system - nuclei+atoms+condensed matter can occur at smaller threshold then corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution inner energy of whole system.
International Nuclear Information System (INIS)
Aquino, V.M. de.
1987-01-01
We have analysed, within a semi classical approach, the influence of external electromagnetic field on phase transitions in gauge theories. The critical temperature was calculated for an Abelian case, scalar electrodynamics, and for an non Abelian case, the Weinberg Salam model. (author)
Spin polarization in high density quark matter under a strong external magnetic field
DEFF Research Database (Denmark)
Tsue, Yasuhiko; Da Providência, João; Providência, Constança
2016-01-01
In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interact...
International Nuclear Information System (INIS)
Zhokhov, R.N.; Kolmakov, P. B.; Zhukovsky, V.Ch.; Klimenko, K.G.
2016-01-01
In the paper there have been studied Gross-Neveu model in (2+1)-dimensional space-time with one compactified dimension in presence of external magnetic field at finite temperature. Magnetic field is directed along the uncompactified dimension that is along the axis of the cylinder on which the system lives. Chiral symmetry breaking and corresponding phase structure of the model is investigated in the leading order of (1/N) expansion
Polarization operator in quantum electrodynamics with a pair-producing external field
International Nuclear Information System (INIS)
Barashev, V.P.; Shvartsman, Sh.M.; Shabad, A.E.
1986-01-01
Various radiative processes with one-photon initial state are treated in QED with pair-producing external field. It is shown that the probabilities of such processes are expressed in terms of two different polarization operators. For the case of a constant field the polarization operator which is expressed through the so-called causal Green electron function, is calculated. This operator has never been calculated previously. It enters the formula for probability of production of N arbitrary pairs by a photon
Nuclear β decay with a massive neutrino in an external electromagnetic field
International Nuclear Information System (INIS)
Ternov, I.M.; Rodionov, V.N.; Zhulego, V.G.; Lobanov, A.E.; Pavlova, O.S.; Dorofeev, O.F.
1986-01-01
Beta decay in the presence of an external electromagnetic field is investigated, taking into account the non-zero neutrino rest mass. The spectrum of electrons and polarisation effects of different orientations of nuclear spin are considered. It is shown that the electromagnetic wave substantially modifies the boundaries of the spectrum of β electrons. The results, which include an analysis of the total decay probability in intense magnetic fields, may have various astrophysical implications. (author)
Brushed permanent magnet DC MLC motor operation in an external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Yun, J.; St Aubin, J.; Rathee, S.; Fallone, B. G. [Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Department of Physics, University of Alberta, 11322-89 Avenue, Edmonton, Alberta T6G 2G7 (Canada); Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada) and Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada)
2010-05-15
Purpose: Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. Methods: The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). Results: In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450{+-}10 G. The carriage motor tolerated up to 2000{+-}10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600{+-}10 G. Conclusions: The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the
Brushed permanent magnet DC MLC motor operation in an external magnetic field.
Yun, J; St Aubin, J; Rathee, S; Fallone, B G
2010-05-01
Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450 +/- 10 G. The carriage motor tolerated up to 2000 +/- 10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600 +/- 10 G. The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the tolerance levels determined, some form of
Brushed permanent magnet DC MLC motor operation in an external magnetic field
International Nuclear Information System (INIS)
Yun, J.; St Aubin, J.; Rathee, S.; Fallone, B. G.
2010-01-01
Purpose: Linac-MR systems for real-time image-guided radiotherapy will utilize the multileaf collimators (MLCs) to perform conformal radiotherapy and tumor tracking. The MLCs would be exposed to the external fringe magnetic fields of the linac-MR hybrid systems. Therefore, an experimental investigation of the effect of an external magnetic field on the brushed permanent magnet DC motors used in some MLC systems was performed. Methods: The changes in motor speed and current were measured for varying external magnetic field strengths up to 2000 G generated by an EEV electromagnet. These changes in motor characteristics were measured for three orientations of the motor in the external magnetic field, mimicking changes in motor orientations due to installation and/or collimator rotations. In addition, the functionality of the associated magnetic motor encoder was tested. The tested motors are used with the Varian 120 leaf Millennium MLC (Maxon Motor half leaf and full leaf motors) and the Varian 52 leaf MKII MLC (MicroMo Electronics leaf motor) including a carriage motor (MicroMo Electronics). Results: In most cases, the magnetic encoder of the motors failed prior to any damage to the gearbox or the permanent magnet motor itself. This sets an upper limit of the external magnetic field strength on the motor function. The measured limits of the external magnetic fields were found to vary by the motor type. The leaf motor used with a Varian 52 leaf MKII MLC system tolerated up to 450±10 G. The carriage motor tolerated up to 2000±10 G field. The motors used with the Varian 120 leaf Millennium MLC system were found to tolerate a maximum of 600±10 G. Conclusions: The current Varian MLC system motors can be used for real-time image-guided radiotherapy coupled to a linac-MR system, provided the fringe magnetic fields at their locations are below the determined tolerance levels. With the fringe magnetic fields of linac-MR systems expected to be larger than the tolerance
Rajnak, Michal; Kurimsky, Juraj; Dolnik, Bystrik; Kopcansky, Peter; Tomasovicova, Natalia; Taculescu-Moaca, Elena Alina; Timko, Milan
2014-09-01
An experimental study of magnetic colloidal particles cluster formation induced by an external electric field in a ferrofluid based on transformer oil is presented. Using frequency domain isothermal dielectric spectroscopy, we study the influence of a test cell electrode separation distance on a low-frequency relaxation process. We consider the relaxation process to be associated with an electric double layer polarization taking place on the particle surface. It has been found that the relaxation maximum considerably shifts towards lower frequencies when conducting the measurements in the test cells with greater electrode separation distances. As the electric field intensity was always kept at a constant value, we propose that the particle cluster formation induced by the external ac electric field accounts for that phenomenon. The increase in the relaxation time is in accordance with the Schwarz theory of electric double layer polarization. In addition, we analyze the influence of a static electric field generated by dc bias voltage on a similar shift in the relaxation maximum position. The variation of the dc electric field for the hysteresis measurements purpose provides understanding of the development of the particle clusters and their decay. Following our results, we emphasize the utility of dielectric spectroscopy as a simple, complementary method for detection and study of clusters of colloidal particles induced by external electric field.
Frants, E. A.; Ganchenko, G. S.; Shelistov, V. S.; Amiroudine, S.; Demekhin, E. A.
2018-02-01
Electrokinetics and the movement of charge-selective micro-granules in an electrolyte solution under the influence of an external electric field are investigated theoretically. Straightforward perturbation analysis is applied to a thin electric double layer and a weak external field, while a numerical solution is used for moderate electric fields. The asymptotic solution enables the determination of the salt concentration, electric charge distribution, and electro-osmotic velocity fields. It may also be used to obtain a simple analytical formula for the electrophoretic velocity in the case of quasi-equilibrium electrophoresis (electrophoresis of the first kind). This formula differs from the famous Helmholtz-Smoluchowski relation, which applies to dielectric microparticles, but not to ion-selective granules. Numerical calculations are used to validate the derived formula for weak external electric fields, but for moderate fields, nonlinear effects lead to a significant increase in electrophoretic mobility and to a transition from quasi-equilibrium electrophoresis of the first kind to nonequilibrium electrophoresis of the second kind. Theoretical results are successfully compared with experimental data.
Solvent effects on ion-receptor interactions in the presence of an external electric field.
Novák, Martin; Foroutan-Nejad, Cina; Marek, Radek
2016-11-09
In this work we investigated the influence of an external electric field on the arrangement of the solvent shells around ions interacting with a carbon-based receptor. Our survey reveals that the mechanism of interaction between a monoatomic ion and a π-type ion receptor varies by the variation in the solvent polarity, the nature of the ion, and the strength of the external field. The characteristics of the ion-surface interaction in nonpolar solvents are similar to those observed in a vacuum. However, in water, we identified two mechanisms. Soft and polarizable ions preferentially interact with the π-receptor. In contrast, two bonded states were found for hard ions. A fully solvated ion, weakly interacting with the receptor at weak field, and a strong π-complex at the strong-field regime were identified. An abrupt variation in the potential energy surface (PES) associated with the rearrangement of the solvation shell on the surface of the receptor induced by an external field was observed both in implicit and explicit solvent environments. The electric field at which the solvation shell breaks is proportional to the hardness of the ion as has been suggested recently based on experimental observations.
Improving Keyhole Stability by External Magnetic Field in Full Penetration Laser Welding
Li, Min; Xu, Jiajun; Huang, Yu; Rong, Youmin
2018-05-01
An external magnetic field was used to improve the keyhole stability in full penetration laser welding 316L steel. The increase of magnetic field strength gave rise to a shorter flying time of the spatter, a weaker size and brightness of the spatter, and a larger spreading area of vapor plume. This suggested that the dynamic behavior of the keyhole was stabilized by the external magnetic field. In addition, a stronger magnetic field could result in a more homogeneous distribution of laser energy, which increased the width of the weld zone, and the height of the bottom weld zone from 381 μm (0 mT) to 605 μm (50 mT). Dendrite and cellular crystal near the weld center disappeared, and grain size was refined. The external magnetic field was beneficial to the keyhole stability and improved the joint quality, because the weld pool was stirred by a Lorentz force resulting from the coupling effect of the magnetic field and inner thermocurrent.
Langel, R. A.; Estes, R. H.
1983-01-01
Data from MAGSAT analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-Earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The MAGSAT data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the Earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results.
Effect of double-shell structure on reduction of field errors in the STP-3(M) reversed-field pinch
International Nuclear Information System (INIS)
Yamada, S.; Masamune, S.; Nagata, A.; Arimoto, H.; Oshiyama, H.; Sato, K.I.
1988-08-01
Reversed-field pinch (RFP) operation on STP-3 (M) proved that the adition of a quasistational vertical field B sub(perpendicular) together with large reduction of irregular magnetic field at the shell gap could remarkably improve properties of the plasma confinement. Here, the gaps of a thick shell is wholely covered with the single primary coil having a shell shape. The measured field error at the gap is as small as 7.5 % of the poloidal field. The application of B sub(perpendicular) sets the plasma at a more perfect equilibrium. In this operation, the plasma resistivety much decreased by a factor 2 and the electron temperature rose up to 0.8 keV. (author)
Sheykhi, A.; Abdollahzadeh, Z.
2018-03-01
We investigate the effects of an external magnetic field as well as exponential nonlinear electrodynamics on the properties of s-wave holographic superconductors. Our strategy for this study is the matching method, which is based on the match of the solutions near the horizon and on the boundary at some intermediate point. When the magnetic field is turned off, we obtain the critical temperature as well as the condensation operator and show that the critical exponent is still 1/2, which is the universal value in the mean field theory. Then, we turn on the magnetic field and obtain the critical magnetic field, B c , in order to study its behavior in terms of the temperature. Interestingly enough, we find that in the presence of exponential nonlinear electrodynamics, the critical temperature decreases, while the critical magnetic field increases compared to the Maxwell case. We also observe that the critical magnetic field increases with increasing the nonlinear parameter b.
International Nuclear Information System (INIS)
Faghihi-Nik, M.; Ghorbanalilu, M.; Shokri, B.
2010-01-01
Complete text of publication follows. Generation of harmonic radiation is an important subject of laser plasma interaction and attracts great attention due to a wide range of applications. It has been seen that intense electromagnetic and quasi-static transverse magnetic fields are generated in laser plasma interaction. An extremely intense magnetic field (up to hundreds of MG) has been observed by experimental measurements in interaction of short laser pulses with plasma. These self-generated or applied magnetic fields affect the propagation of the laser pulses. In most laser interactions with homogeneous plasma, odd harmonics of laser frequency are generated. In this paper, we point out the possibility of even harmonics generation when a linearly polarized laser beam propagates in homogeneous plasma in the presence of a transverse magnetic field. It is shown that applying external field induces a transverse current density oscillating twice of the laser field which leds to generation of second harmonic radiation. This current density is derived using the perturbation method, and the steady state amplitude of the second harmonic obtained by solution of the wave equation. By the same procedure the current density and then the steady state amplitude of higher order harmonics are calculated. The efficiency of harmonic generation (the ratio of harmonic power to incident power) is a drastically function of the strength of external magnetic field. It is found that the efficiency of even harmonics is zero in the absence of magnetic field and increases as the magnetic field is increased. For odd harmonics, applying the external magnetic field enhances the generated harmonics as well. The conversion efficiency also increases with increase in plasma density and intensity of the laser beam.
The importance of matched poloidal spectra to error field correction in DIII-D
Energy Technology Data Exchange (ETDEWEB)
Paz-Soldan, C., E-mail: paz-soldan@fusion.gat.com; Lanctot, M. J.; Buttery, R. J.; La Haye, R. J.; Strait, E. J. [General Atomics, P.O. Box 85608, San Diego, California 92121 (United States); Logan, N. C.; Park, J.-K.; Solomon, W. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Shiraki, D.; Hanson, J. M. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
2014-07-15
Optimal error field correction (EFC) is thought to be achieved when coupling to the least-stable “dominant” mode of the plasma is nulled at each toroidal mode number (n). The limit of this picture is tested in the DIII-D tokamak by applying superpositions of in- and ex-vessel coil set n = 1 fields calculated to be fully orthogonal to the n = 1 dominant mode. In co-rotating H-mode and low-density Ohmic scenarios, the plasma is found to be, respectively, 7× and 20× less sensitive to the orthogonal field as compared to the in-vessel coil set field. For the scenarios investigated, any geometry of EFC coil can thus recover a strong majority of the detrimental effect introduced by the n = 1 error field. Despite low sensitivity to the orthogonal field, its optimization in H-mode is shown to be consistent with minimizing the neoclassical toroidal viscosity torque and not the higher-order n = 1 mode coupling.
Topology optimized and 3D printed polymer-bonded permanent magnets for a predefined external field
Huber, C.; Abert, C.; Bruckner, F.; Pfaff, C.; Kriwet, J.; Groenefeld, M.; Teliban, I.; Vogler, C.; Suess, D.
2017-08-01
Topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics. Additive manufacturing of polymer-bonded magnets with an end-user 3D printer can be used to manufacture permanent magnets with structures that had been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic systems with specific properties. The topology optimization framework is simple, fast, and accurate. It can also be used for the reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generates a linear external field above the magnet is presented. With a volume constraint, the amount of magnetic material can be minimized without losing performance. Simulations and measurements of the printed systems show very good agreement.
Dynamic characteristics of non-ideal plasmas in an external high frequency electric field
Energy Technology Data Exchange (ETDEWEB)
Adamyan, V M [Department of Theoretical Physics, I. I. Mechnikov Odessa National University, 65026 Odessa (Ukraine); Djuric, Z [Silvaco Data System, Silvaco Technology Centre, Compass Point, St. Ives PE27 5JL (United Kingdom); Mihajlov, A A [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro); Sakan, N M [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro); Tkachenko, I M [Department of Applied Mathematics, ETSII, Polytechnic University of Valencia, Camino de Vera s/n, Valencia 46022 (Spain)
2004-07-21
The dynamic electric conductivity, dielectric permeability and refraction and reflection coefficients of a completely ionized gaseous plasma in a high frequency (HF) external electric field are calculated. These results are obtained within the self-consistent field approach developed earlier for the static conductivity determination. The plasma electron density, N{sub e}, and temperature, T, varied within the following limits: 10{sup 19} {<=} N{sub e} {<=} 10{sup 21} cm{sup -3} and 2 x 10{sup 4} {<=} T {<=} 10{sup 6} K, respectively. The external electric field frequency, f, varied in the range 3 GHz{<=} f {<=} 0.05{omicron}{sub p}, where {omicron}{sub p} is the circular plasma frequency. Thus, the upper limit for f is either in the microwave or in the far infrared frequency band. The final results are shown in a parameterized form, suitable for laboratory applications.
Dynamic characteristics of non-ideal plasmas in an external high frequency electric field
International Nuclear Information System (INIS)
Adamyan, V M; Djuric, Z; Mihajlov, A A; Sakan, N M; Tkachenko, I M
2004-01-01
The dynamic electric conductivity, dielectric permeability and refraction and reflection coefficients of a completely ionized gaseous plasma in a high frequency (HF) external electric field are calculated. These results are obtained within the self-consistent field approach developed earlier for the static conductivity determination. The plasma electron density, N e , and temperature, T, varied within the following limits: 10 19 ≤ N e ≤ 10 21 cm -3 and 2 x 10 4 ≤ T ≤ 10 6 K, respectively. The external electric field frequency, f, varied in the range 3 GHz≤ f ≤ 0.05ο p , where ο p is the circular plasma frequency. Thus, the upper limit for f is either in the microwave or in the far infrared frequency band. The final results are shown in a parameterized form, suitable for laboratory applications
The influence of an external magnetic axial field on the autocompression of a plasma column
International Nuclear Information System (INIS)
Zoler, D.
1979-01-01
The results of theoretical research on the autocompression of a plasma column under the influence of its own azimuthal field, in the presence of an external magnetic axial field are presented in this paper. Focussed plasma installations are important both for the fundamental researches which can be undertaken on great density and high temperature plasma and for their possible applications since they can be used as sources of neutrons, Roentgen radiations and to obtain heavy ions. The important parameters of plasma have been studied comparatively in the presence or absence of the external magnetic axial field by means of a method of numerical simulation of phenomena from focussed plasma in a complex MHD system taking into account the dissipative and transport phenomena. The numerical data used in chapter 5 are in agreement with the parameters of the experimental installation produced at IFTAR-Bucharest, which have been indicated to us by the members of the focussed plasma staff. (author)
Tiutiunnyk, A.; Mora-Ramos, M. E.; Morales, A. L.; Duque, C. M.; Restrepo, R. L.; Ungan, F.; Martínez-Orozco, J. C.; Kasapoglu, E.; Duque, C. A.
2017-02-01
In this work we shall present a study of inelastic light scattering involving inter-subband electron transitions in coupled GaAs-(Ga,Al)As quantum wells. Calculations include the electron related Raman differential cross section and Raman gain. The effects of an external nonresonant intense laser field are used in order to tune these output properties. The confined electron states will be described by means of a diagonalization procedure within the effective mass and parabolic band approximations. It is shown that the application of the intense laser field can produce values of the intersubband electron Raman gain above 400 cm-1. The system proposed here is an alternative choice for the development of AlxGa1-xAs semiconductor laser diodes that can be tuned via an external nonresonant intense laser field.
A shear-mode magnetoelectric heterostructure for harvesting external magnetic field energy
He, Wei; Zhang, Jitao; Lu, Yueran; Yang, Aichao; Qu, Chiwen; Yuan, Shuai
2017-03-01
In this paper, a magnetoelectric (ME) energy harvester is presented for scavenging external magnetic field energy. The proposed heterostructure consists of a Terfenol-D plate, a piezoelectric PZT5H plate, a NdFeB magnet, and two concentrators. The external magnetic field is concentrated to the Terfenol-D plate and the PZT5H plate working in shear-mode, which can potentially increase the magnetoelectric response. Experiments have been performed to verify the feasibility of the harvester. Under the magnetic field of 0.6 Oe, the device produces a RMS voltage of 0.53 V at the resonant frequency of 32.6 kHz. The corresponding output power reaches 44.96 μW across a 3.1 kΩ matching resistor.
International Nuclear Information System (INIS)
Zhao, Zixu; Pan, Qiyuan; Jing, Jiliang
2014-01-01
We employ the matching method to analytically investigate the holographic superconductors with Lifshitz scaling in an external magnetic field. We discuss systematically the restricted conditions for the matching method and find that this analytic method is not always powerful to explore the effect of external magnetic field on the holographic superconductors unless the matching point is chosen in an appropriate range and the dynamical exponent z satisfies the relation z=d−1 or z=d−2. From the analytic treatment, we observe that Lifshitz scaling can hinder the condensation to be formed, which can be used to back up the numerical results. Moreover, we study the effect of Lifshitz scaling on the upper critical magnetic field and reproduce the well-known relation obtained from Ginzburg–Landau theory
Collective modes of the Nambu--Jona-Lasinio model with an external U(1) gauge field
International Nuclear Information System (INIS)
Klevansky, S.P.; Jaenicke, J.; Lemmer, R.H.
1991-01-01
The effect of external color fields on the collective modes of the SU L (2)xSU R (2) chiral flavor version of the Nambu--Jona-Lasinio model is studied analytically in a U(1) approximation to the gauge fields. We show that the scalar and pseudoscalar modes respond differently to external chromomagnetic and -electric fields. In the former case, in which chiral asymmetry is enhanced, the modes remain well separated and vary slowly with the field, while in the latter case the scalar mode drops rapidly to become degenerate with the pseudoscalar mode in the chiral limit. In this regime, both modes are weakly coupled to quark matter, and the pseudoscalar pion mode in particular survives as a well-defined excitation as it enters the pair continuum. The Goldberger-Treiman relation, which is shown to hold in the presence of external fields, is responsible for this behavior. Chromoelectric and -magnetic polarizabilities are seen to be equal and opposite with absolute values β σ =2.0α s and β π =0.03α s for the scalar and pseudoscalar modes respectively
Stable magnetization of iron filled carbon nanotube MFM probes in external magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Wolny, Franziska; Weissker, Uhland; Muehl, Thomas; Lutz, Matthias U; Mueller, Christian; Leonhardt, Albrecht; Buechner, Bernd, E-mail: f.wolny@ifw-dresden.d [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany)
2010-01-01
We present results on the application of an iron filled carbon nanotube (Fe-CNT) as a probe for magnetic force microscopy (MFM) in an external magnetic field. If an external field is applied parallel to the sample surface, conventional ferromagnetically coated MFM probes often have the disadvantage that the magnetization of the coating turns towards the direction of the applied field. Then it is difficult to distinguish the effect of the external field on the sample from those on the MFM probe. The Fe-CNT MFM probe has a large shape anisotropy due to the high aspect ratio of the enclosed iron nanowire. Thanks to this the direction of the magnetization stays mainly oriented along the long nanotube axis in in-plane fields up to our experimental limit of 250 mT. Thus, the quality of the MFM images remains unchanged. Apart from this, it is shown that Fe-CNT MFM probe yields a very good magnetic resolution of about 25 nm due to the small diameter of the iron filling.
Effect of sample shape on nonlinear magnetization dynamics under an external magnetic field
International Nuclear Information System (INIS)
Vagin, Dmitry V.; Polyakov, Oleg P.
2008-01-01
Effect of sample shape on the nonlinear collective dynamics of magnetic moments in the presence of oscillating and constant external magnetic fields is studied using the Landau-Lifshitz-Gilbert (LLG) approach. The uniformly magnetized sample is considered to be an ellipsoidal axially symmetric particle described by demagnetization factors and uniaxial crystallographic anisotropy formed some angle with an applied field direction. It is investigated as to how the change in particle shape affects its nonlinear magnetization dynamics. To produce a regular study, all results are presented in the form of bifurcation diagrams for all sufficient dynamics regimes of the considered system. In this paper, we show that the sample's (particle's) shape and its orientation with respect to the external field (system configuration) determine the character of magnetization dynamics: deterministic behavior and appearance of chaotic states. A simple change in the system's configuration or in the shapes of its parts can transfer it from chaotic to periodic or even static regime and back. Moreover, the effect of magnetization precession stall and magnetic moments alignment parallel or antiparallel to the external oscillating field is revealed and the way of control of such 'polarized' states is found. Our results suggest that varying the particle's shape and fields' geometry may provide a useful way of magnetization dynamics control in complex magnetic systems
Error Analysis and Calibration Method of a Multiple Field-of-View Navigation System
Shi, Shuai; Zhao, Kaichun; You, Zheng; Ouyang, Chenguang; Cao, Yongkui; Wang, Zhenzhou
2017-01-01
The Multiple Field-of-view Navigation System (MFNS) is a spacecraft subsystem built to realize the autonomous navigation of the Spacecraft Inside Tiangong Space Station. This paper introduces the basics of the MFNS, including its architecture, mathematical model and analysis, and numerical simulation of system errors. According to the performance requirement of the MFNS, the calibration of both intrinsic and extrinsic parameters of the system is assumed to be essential and pivotal. Hence, a n...
Energy Technology Data Exchange (ETDEWEB)
Ayala Guardia, Fidel
2011-10-15
The aSPECT spectrometer has been designed to measure, with high precision, the recoil proton spectrum of the free neutron decay. From this spectrum, the electron antineutrino angular correlation coefficient a can be extracted with high accuracy. The goal of the experiment is to determine the coefficient a with a total relative error smaller than 0.3%, well below the current literature value of 5%. First measurements with the aSPECT spectrometer were performed in the Forschungs-Neutronenquelle Heinz Maier-Leibnitz in Munich. However, time-dependent background instabilities prevented us from reporting a new value of a. The contents of this thesis are based on the latest measurements performed with the aSPECT spectrometer at the Institut Laue-Langevin (ILL) in Grenoble, France. In these measurements, background instabilities were considerably reduced. Furthermore, diverse modifications intended to minimize systematic errors and to achieve a more reliable setup were successfully performed. Unfortunately, saturation effects of the detector electronics turned out to be too high to determine a meaningful result. However, this and other systematics were identified and decreased, or even eliminated, for future aSPECT beamtimes. The central part of this work is focused on the analysis and improvement of systematic errors related to the aSPECT electromagnetic fields. This work yielded in many improvements, particularly in the reduction of the systematic effects due to electric fields. The systematics related to the aSPECT magnetic field were also minimized and determined down to a level which permits to improve the present literature value of a. Furthermore, a custom NMR-magnetometer was developed and improved during this thesis, which will lead to reduction of magnetic field-related uncertainties down to a negligible level to determine a with a total relative error of at least 0.3%.
International Nuclear Information System (INIS)
Ayala Guardia, Fidel
2011-10-01
The aSPECT spectrometer has been designed to measure, with high precision, the recoil proton spectrum of the free neutron decay. From this spectrum, the electron antineutrino angular correlation coefficient a can be extracted with high accuracy. The goal of the experiment is to determine the coefficient a with a total relative error smaller than 0.3%, well below the current literature value of 5%. First measurements with the aSPECT spectrometer were performed in the Forschungs-Neutronenquelle Heinz Maier-Leibnitz in Munich. However, time-dependent background instabilities prevented us from reporting a new value of a. The contents of this thesis are based on the latest measurements performed with the aSPECT spectrometer at the Institut Laue-Langevin (ILL) in Grenoble, France. In these measurements, background instabilities were considerably reduced. Furthermore, diverse modifications intended to minimize systematic errors and to achieve a more reliable setup were successfully performed. Unfortunately, saturation effects of the detector electronics turned out to be too high to determine a meaningful result. However, this and other systematics were identified and decreased, or even eliminated, for future aSPECT beamtimes. The central part of this work is focused on the analysis and improvement of systematic errors related to the aSPECT electromagnetic fields. This work yielded in many improvements, particularly in the reduction of the systematic effects due to electric fields. The systematics related to the aSPECT magnetic field were also minimized and determined down to a level which permits to improve the present literature value of a. Furthermore, a custom NMR-magnetometer was developed and improved during this thesis, which will lead to reduction of magnetic field-related uncertainties down to a negligible level to determine a with a total relative error of at least 0.3%.
Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd
2016-08-01
Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type.
International Nuclear Information System (INIS)
Pan, Zhao; Thomson, Scott; Whitehead, Jared; Truscott, Tadd
2016-01-01
Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type. (paper)
Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd
2016-01-01
Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type. PMID:27499587
Energy Technology Data Exchange (ETDEWEB)
Klimachkov, D.A., E-mail: klimachkovdmitry@gmail.com [Space Research Institute of Russian Academy of Science, 84/32, Profsoyuznaya str., Moscow, 117997 (Russian Federation); Petrosyan, A.S. [Space Research Institute of Russian Academy of Science, 84/32, Profsoyuznaya str., Moscow, 117997 (Russian Federation); Moscow Institute of Physics and Technology (State University), 9 Institutskyi per., Dolgoprudny, Moscow Region, 141700 (Russian Federation)
2017-01-15
This article deals with magnetohydrodynamic (MHD) flows of a thin rotating layer of astrophysical plasma in external magnetic field. We use the shallow water approximation to describe thin rotating plasma layer with a free surface in a vertical external magnetic field. The MHD shallow water equations with external vertical magnetic field are revised by supplementing them with the equations that are consequences of the magnetic field divergence-free conditions and reveal the existence of third component of the magnetic field in such approximation providing its relation with the horizontal magnetic field. It is shown that the presence of a vertical magnetic field significantly changes the dynamics of the wave processes in astrophysical plasma compared to the neutral fluid and plasma layer in a toroidal magnetic field. The equations for the nonlinear wave packets interactions are derived using the asymptotic multiscale method. The equations for three magneto-Poincare waves interactions, for three magnetostrophic waves interactions, for the interactions of two magneto-Poincare waves and for one magnetostrophic wave and two magnetostrophic wave and one magneto-Poincare wave interactions are obtained. The existence of parametric decay and parametric amplifications is predicted. We found following four types of parametric decay instabilities: magneto-Poincare wave decays into two magneto-Poincare waves, magnetostrophic wave decays into two magnetostrophic waves, magneto-Poincare wave decays into one magneto-Poincare wave and one magnetostrophic wave, magnetostrophic wave decays into one magnetostrophic wave and one magneto-Poincare wave. Following mechanisms of parametric amplifications are found: parametric amplification of magneto-Poincare waves, parametric amplification of magnetostrophic waves, magneto-Poincare wave amplification in magnetostrophic wave presence and magnetostrophic wave amplification in magneto-Poincare wave presence. The instabilities growth rates
The dust characteristics in the collisional plasma sheath at the presence of external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Shourkaei, Hossein Akbarian [AEOI, Tehran (Iran, Islamic Republic of). Plasma Physics Research Group
2015-05-15
The characteristics of dust in a plasma sheath are investigated in the presence of an external magnetic field and taking into account neutral collision forces. By using the fluid model, the continuity and momentum equations of ions and dusts are solved numerically with various magnitudes of collision force. In various magnitude and directions of the magnetic field, the electron and ion density distribution, ion flow velocity, electron potential have been calculated. It is shown that magnetic field has obvious effect on the plasma sheath and the collision force reduces the dust kinetic energy.
The effect of external magnetic field changing on the correlated quantum dot dynamics
Mantsevich, V. N.; Maslova, N. S.; Arseyev, P. I.
2018-06-01
The non-stationary response of local magnetic moment to abrupt switching "on" and "off" of external magnetic field was studied for a single-level quantum dot (QD) coupled to a reservoir. We found that transient processes look different for the shallow and deep localized energy level. It was demonstrated that for deep energy level the relaxation rates of the local magnetic moment strongly differ in the case of magnetic field switching "on" or "off". Obtained results can be applied in the area of dynamic memory devices stabilization in the presence of magnetic field.
Plasma expansion into a vacuum with an arbitrarily oriented external magnetic field
Energy Technology Data Exchange (ETDEWEB)
García-Rubio, F., E-mail: fernando.garcia.rubio@upm.es; Sanz, J. [E.T.S.I. Aeronáutica y del Espacio, Universidad Politécnica de Madrid, Madrid 28040 (Spain); Ruocco, A. [Universitá degli studi di Napoli Federico II, 80138 Napoli (Italy)
2016-01-15
Plasma expansion into a vacuum with an external magnetic field is studied under the ideal magnetohydrodynamic hypothesis. The inclination of the magnetic field with respect to the expansion direction is arbitrary, and both the perpendicular and the oblique cases are separately analyzed. A self-similar solution satisfying the boundary conditions is obtained. The interface with the vacuum is treated as a fluid surface, and jump conditions concerning the momentum conservation are imposed. The effect of the intensity of the magnetic field and its inclination is thoroughly studied, and the consistency of the solution for small and large inclinations is investigated.
Destruction of Spiral Wave Using External Electric Field Modulated by Logistic Map
International Nuclear Information System (INIS)
Ma Jun; Chen Yong; Jin Wuyin
2007-01-01
Evolution of spiral wave generated from the excitable media within the Barkley model is investigated. The external gradient electric field modulated by the logistic map is imposed on the media (along x- and y-axis). Drift and break up of spiral wave are observed when the amplitude of the electric field is modulated by the chaotic signal from the logistic map, and the whole system could become homogeneous finally and the relevant results are compared when the gradient electric field is modulated by the Lorenz or Roessler chaotic signal.
Elliptic annular Josephson tunnel junctions in an external magnetic field: the statics
DEFF Research Database (Denmark)
Monaco, Roberto; Granata, Carmine; Vettoliere, Antonio
2015-01-01
We have investigated the static properties of one-dimensional planar Josephson tunnel junctions (JTJs) in the most general case of elliptic annuli. We have analyzed the dependence of the critical current in the presence of an external magnetic field applied either in the junction plane...... symmetric electrodes a transverse magnetic field is equivalent to an in-plane field applied in the direction of the current flow. Varying the ellipse eccentricity we reproduce all known results for linear and ring-shaped JTJs. Experimental data on high-quality Nb/Al-AlOx/Nb elliptic annular junctions...
Sammut, N J; Bottura, L; Deferne, G; Lamont, M; Miles, J; Sanfilippo, S; Strzelczyk, M; Venturini-Delsolaro, W; Xydi, P
2008-01-01
In order to reduce the burden on the beam-based feedback, the Large Hadron Collider control system is equipped with the Field Description for the LHC (FiDeL) which provides a forecast of the magnetic field and the multipole field errors. FiDeL has recently been extensively tested at CERN to determine main field tracking, multipole forecasting and compensation accuracy. This paper describes the rationale behind the tests, the procedures employed to power the main magnets and their correctors, and finally, we present the results obtained. We also give an indication of the prediction accuracy that the system can deliver during the operation of the LHC and we discuss the implications that these will have on the machine performance.
Effect of External Electric Field on Substrate Transport of a Secondary Active Transporter.
Zhang, Ji-Long; Zheng, Qing-Chuan; Yu, Li-Ying; Li, Zheng-Qiang; Zhang, Hong-Xing
2016-08-22
Substrate transport across a membrane accomplished by a secondary active transporter (SAT) is essential to the normal physiological function of living cells. In the present research, a series of all-atom molecular dynamics (MD) simulations under different electric field (EF) strengths was performed to investigate the effect of an external EF on the substrate transport of an SAT. The results show that EF both affects the interaction between substrate and related protein's residues by changing their conformations and tunes the timeline of the transport event, which collectively reduces the height of energy barrier for substrate transport and results in the appearance of two intermediate conformations under the existence of an external EF. Our work spotlights the crucial influence of external EFs on the substrate transport of SATs and could provide a more penetrating understanding of the substrate transport mechanism of SATs.
Social Networks and Externalities from Gift Exchange: Evidence from A Field Experiment.
Currie, Janet; Lin, Wanchuan; Meng, Juanjuan
2013-11-01
This paper asks whether gift exchange generates externalities for people outside of the bilateral relationship between the gift giver and recipient, and whether the nature of this relationship is affected by social networks. We examine this question in the context of a field experiment in urban Chinese hospital outpatient clinics. We first show that when patients give a small gift, doctors reciprocate with better service and a fewer unnecessary prescriptions of antibiotics. We then show that gift giving creates externalities for third parties. If two patients, A and B are perceived as unrelated, B receives worse care when A gives a gift. However, if A identifies B as a friend, then both A and B benefit from A's gift giving. Hence, we show that gift giving can create positive or negative externalities, depending on the giver's social distance to the third party.
Social Networks and Externalities from Gift Exchange: Evidence from A Field Experiment☆
Currie, Janet; Lin, Wanchuan; Meng, Juanjuan
2016-01-01
This paper asks whether gift exchange generates externalities for people outside of the bilateral relationship between the gift giver and recipient, and whether the nature of this relationship is affected by social networks. We examine this question in the context of a field experiment in urban Chinese hospital outpatient clinics. We first show that when patients give a small gift, doctors reciprocate with better service and a fewer unnecessary prescriptions of antibiotics. We then show that gift giving creates externalities for third parties. If two patients, A and B are perceived as unrelated, B receives worse care when A gives a gift. However, if A identifies B as a friend, then both A and B benefit from A’s gift giving. Hence, we show that gift giving can create positive or negative externalities, depending on the giver’s social distance to the third party. PMID:26949272
Effects of external magnetic field on biodistribution of nanoparticles: A histological study
Energy Technology Data Exchange (ETDEWEB)
Wu, Tony [Department of Neurology, Chang Gung University College of Medicine and Memorial Hospital, 199 Tung-Hwa N Rd, Taipei, Taiwan (China); Hua, M.-Y. [Department of Chemical and Material Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan, Taiwan (China); Chen Jyhping [Department of Chemical and Material Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan, Taiwan (China); Wei, K.-C. [Department of Neurosurgery, Chang Gung University College of Medicine and Memorial Hospital, 199 Tung-Hwa N Rd, Taipei, Taiwan (China); Jung, S.-M. [Department of Pathology, Chang Gung University College of Medicine and Memorial Hospital, 199 Tung-Hwa N Rd, Taipei, Taiwan (China); Chang, Y.-J. [Department of Neurology, Chang Gung University College of Medicine and Memorial Hospital, 199 Tung-Hwa N Rd, Taipei, Taiwan (China); Jou, M.-J. [Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Ma, Y.-H. [Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China)]. E-mail: yhma@mail.cgu.edu.tw
2007-04-15
This study investigates the effect of external magnetic fields on the biodistribution of nanoparticles (NP). A NdFeB magnet of 2.4 kG was externally applied over the left femoral artery or right kidney. The 250 nm dextran-coated Fe{sub 3}O{sub 4} NP was injected via tail vein in healthy rats, and organs were taken 1 or 24 h later. Prussian blue stain revealed that NP were more rapidly retained in the liver and spleen than in the lungs. NP aggregation observed in the kidney and femoral artery after application of external magnets was time dependent. Hollow organs such as the intestine, colon, and urinary bladder retained little NP.
Effects of external magnetic field on biodistribution of nanoparticles: A histological study
International Nuclear Information System (INIS)
Wu, Tony; Hua, M.-Y.; Chen Jyhping; Wei, K.-C.; Jung, S.-M.; Chang, Y.-J.; Jou, M.-J.; Ma, Y.-H.
2007-01-01
This study investigates the effect of external magnetic fields on the biodistribution of nanoparticles (NP). A NdFeB magnet of 2.4 kG was externally applied over the left femoral artery or right kidney. The 250 nm dextran-coated Fe 3 O 4 NP was injected via tail vein in healthy rats, and organs were taken 1 or 24 h later. Prussian blue stain revealed that NP were more rapidly retained in the liver and spleen than in the lungs. NP aggregation observed in the kidney and femoral artery after application of external magnets was time dependent. Hollow organs such as the intestine, colon, and urinary bladder retained little NP
Energy Technology Data Exchange (ETDEWEB)
Ben-Yoav, Hadar, E-mail: benyoav@post.tau.ac.il [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Amzel, Tal [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Sternheim, Marek [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel); Belkin, Shimshon [Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Rubin, Adi [Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, 69978 (Israel); Shacham-Diamand, Yosi [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Freeman, Amihay [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel)
2011-11-01
Highlights: > We present an electrochemical whole-cell biochip that can apply electric fields. > We examine the integration of cells on a biochip using electrophoretic deposition. > The effect of electric fields on the whole-cell biosensor has been demonstrated. > Relatively short DC electric pulse improves the performance of whole-cell biosensors. > Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that relatively
International Nuclear Information System (INIS)
Ben-Yoav, Hadar; Amzel, Tal; Sternheim, Marek; Belkin, Shimshon; Rubin, Adi; Shacham-Diamand, Yosi; Freeman, Amihay
2011-01-01
Highlights: → We present an electrochemical whole-cell biochip that can apply electric fields. → We examine the integration of cells on a biochip using electrophoretic deposition. → The effect of electric fields on the whole-cell biosensor has been demonstrated. → Relatively short DC electric pulse improves the performance of whole-cell biosensors. → Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that
On the interaction between the external magnetic field and nanofluid inside a vertical square duct
Directory of Open Access Journals (Sweden)
Kashif Ali
2015-10-01
Full Text Available In this paper, we numerically study how the external magnetic field influences the flow and thermal characteristics of nanofluid inside a vertical square duct. The flow is considered to be laminar and hydrodynamically as well as thermally developed, whereas the thermal boundary condition of constant heat flux per unit axial length with constant peripheral temperature at any cross section, is assumed. The governing equations are solved using the spectral method and the finite difference method. Excellent comparison is noted in the numerical results given by the two methods but the spectral method is found to be superior in terms of both efficiency and accuracy. We have noted that the flow reversal due to high Raleigh number may be controlled by applying an external magnetic field of suitable strength. Moreover, the Nusselt number is found to be almost a linear function of the nanoparticle volume fraction parameter, for different values of the Raleigh number and the magnetic parameter.
International Nuclear Information System (INIS)
Bramantya, M A; Sawada, T; Motozawa, M
2010-01-01
Ultrasonic propagation velocity in a magnetic fluid (MF) and magnetorheological fluid (MRF) changes with the application of an external magnetic field. The formation of clustering structures inside the MF and MRF clearly has an influence on the ultrasonic propagation velocity. Therefore, we propose a qualitative analysis of these structures by measuring properties of ultrasonic propagation. Since MF and MRF are opaque, non-contact inspection using the ultrasonic technique can be very useful for analyzing the inner structures of MF and MRF. In this study, we measured ultrasonic propagation velocity in a hydrocarbon-based MF and MRF precisely. Based on these results, the clustering structures of these fluids are analyzed experimentally in terms of elapsed time dependence and the effect of external magnetic field strength. The results reveal hysteresis and anisotropy in the ultrasonic propagation velocity. We also discuss differences of ultrasonic propagation velocity between MF and MRF.
Electron drag by solitons in superlattices in an external magnetic field
International Nuclear Information System (INIS)
Vyazovskii, M.V.; Syrodoev, G.A.
1996-01-01
The soliton-electric effect accompanying the propagation of an electromagnetic soliton along an axis of a superlattice in an external magnetic field directed along the magnetic field of the soliton is studied. It is assumed that the duration γ-1 of the soliton pulse is much shorter than the free flight time of an electron. It is shown that in the absence of a constant magnetic field the drag current varies as sin(αsech2γt) (α is a constant determined by the parameters of the superlattice). In the presence of a constant magnetic field of intensity H0>>Hs, where Hs is the amplitude of the soliton field, the drag current oscillates
Linear and nonlinear absorption coefficients of spherical quantum dot inside external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Çakır, Bekir, E-mail: bcakir@selcuk.edu.tr [Physics Department, Faculty of Science, Selcuk University, Campus, 42075 Konya (Turkey); Yakar, Yusuf, E-mail: yuyakar@yahoo.com [Physics Department, Faculty of Arts and Science, Aksaray University, Campus, 68100 Aksaray (Turkey); Özmen, Ayhan [Physics Department, Faculty of Science, Selcuk University, Campus, 42075 Konya (Turkey)
2017-04-01
We have calculated the wavefunctions and energy eigenvalues of spherical quantum dot with infinite potential barrier inside uniform magnetic field. In addition, we have investigated the magnetic field effect on optical transitions between Zeeman energy states. The results are expressed as a function of dot radius, incident photon energy and magnetic field strength. The results present that, in large dot radii, the external magnetic field affects strongly the optical transitions between Zeeman states. In the strong spatial confinement case, energy level is relatively insensitive to the magnetic field, and electron spatial confinement prevails over magnetic confinement. Also, while m varies from −1 to +1, the peak positions of the optical transitions shift toward higher energy (blueshift).
The effect of axial external magnetic field on tungsten inert gas welding of magnesium alloy
Li, Caixia; Zhang, Xiaofeng; Wang, Jing
2018-04-01
The influences of axial external magnetic field on the microstructure and mechanical property of the AZ31 magnesium (Mg) alloy joints were studied. The microstructure of Mg alloy joint consisted of the weld seam, heat affected zone and base metal zone. The average grain size of weld seam welded with magnetic field is 39 μm, which is 38% smaller than that of the joint welded with absence of magnetic field. And the microhardness of weld seam increases with the help of magnetic field treatment, owing to the coarse grain refinement. With coil current of 2.0A, the maximum mechanical property of joint increases 6.7% to 255 MPa over the specimen without magnetic field treatment. Furthermore, fracture location is near heat affected area and the fracture surface is characterized with ductile fracture.
The effect of an external electric field on the growth of incongruent-melting material
Uda, Satoshi; Huang, Xinming; Wang, Shou-Qi
2005-02-01
The significance of an electric field on the crystallization process is differentiated into two consequences; (i) thermodynamic effect and (ii) growth-dynamic effect. The former modifies the chemical potential of the associated phases which changes the equilibrium phase relationship while the latter influences the solute transport, growth kinetics, surface creation and defect generation during growth. The intrinsic electric field generating during growth is attributed to the crystallization-related electromotive force and the thermoelectric power driven by the temperature gradient at the interface which influences the solute transport and solute partitioning. The external electric field was applied to the growth apparatus in the ternary system of La2O3- Ga2O3- SiO2 so that the chemical potential of both solid and liquid phases changed leading to the variation of the equilibrium phase relationship. Imposing a 500 V/cm electric field on the system moved the boundary of primary phase field of lanthanum gallate ( LaGaO3) and Ga-bearing lanthanum silicate ( La14GaxSi9-xO) toward the SiO2 apex by 5 mol% which clearly demonstrated the change of the phase relationship by the external electric field.
Effects of external radiation fields on line emission—application to star-forming regions
Energy Technology Data Exchange (ETDEWEB)
Chatzikos, Marios; Ferland, G. J. [University of Kentucky, Lexington, KY 40506 (United States); Williams, R. J. R. [AWE plc, Aldermaston, Reading RG7 4PR (United Kingdom); Porter, Ryan [Department of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451 (United States); Van Hoof, P. A. M., E-mail: mchatzikos@gmail.com [Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Uccle (Belgium)
2013-12-20
A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous results obtained under ad hoc assumptions or with the two-level system, but can be applied to complex many-level models of atoms or molecules. This treatment is in the development version of the spectral synthesis code CLOUDY. We examine the spectrum of a Spitzer cloud embedded in the local interstellar radiation field and show that about 60% of its emission lines are sensitive to background subtraction. We argue that this geometric approach could provide an additional tool toward understanding the complex radiation fields of starburst galaxies.
External electric field effects on Schottky barrier at Gd3N@C80/Au interface
Onishi, Koichi; Nakashima, Fumihiro; Jin, Ge; Eto, Daichi; Hattori, Hayami; Miyoshi, Noriko; Kirimoto, Kenta; Sun, Yong
2017-08-01
The effects of the external electric field on the height of the Schottky barrier at the Gd3N@C80/Au interface were studied by measuring current-voltage characteristics at various temperatures from 200 K to 450 K. The Gd3N@C80 sample with the conduction/forbidden/valence energy band structure had a face-centered cubic crystal structure with the average grain size of several nanometers. The height of the Gd3N@C80/Au Schottky barrier was confirmed to be 400 meV at a low electric field at room temperature. Moreover, the height decreases with the increasing external electric field through a change of permittivity in the Gd3N@C80 sample due to a polarization of the [Gd3] 9 +-[N3 -+("separators="|C80 ) 6 -] dipoles in the Gd3N@C80 molecule. The field-dependence of the barrier height can be described using a power math function of the electric field strength. The results of the field-dependent barrier height indicate that the reduction in the Schottky barrier is due to an image force effect of the transport charge carrier at the Gd3N@C80/Au interface.
International Nuclear Information System (INIS)
Yu-Yan, Shen; Xiao-Gang, Chen; Wei, Cui; Yan-Hua, Hao; Qian-Qian, Li
2009-01-01
This paper uses the perturbation method to study effective response of nonlinear cylindrical coated composites. Under the external AC and DC electric field E a (1 + sin ωt), the local potentials of composites at all harmonic frequencies are induced. An effective nonlinear response to composite is given for the cylindrical coated inclusions in the dilute limit. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
External magnetic field induced anomalies of spin nuclear dynamics in thin antiferromagnetic films
International Nuclear Information System (INIS)
Tarasenko, S.V.
1995-01-01
It is shown that if the thickness of homogeneously magnetized plate of high-axial antiferromagnetic within H external magnetic field becomes lower the critical one, then the effect of dynamic magnetoelastic interaction on Soul-Nakamura exchange of nuclear spins results in formation of qualitatively new types of spreading nuclear spin waves no else compared neither within the model of unrestricted magnetic nor at H = 0 in case of thin plate of high-axial antiferromagnetic. 10 refs
Classical limit of a quantum particle in an external Yang-Mills field
International Nuclear Information System (INIS)
Moschella, U.
1989-01-01
It is studied the classical limit of a quantum particle in an external non-abelian gauge field. It is shown that the unitary group describing the quantum fluctuations around any classic phase orbit has a classical limit when h tends to zero under very general conditions on the potentials. It is also proved the self-adjointness of the Hamilton's operator of the quantum theory for a large class of potentials. Some applications of the theory are finally exposed
Gareev, F. A.; Zhidkova, I. E.
2006-01-01
We proposed a new mechanism of LENR: cooperative processes in whole system - nuclei+atoms+condensed matter can occur at smaller threshold energies then corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution inner energy of whole system.
New cooperative mechanisms of low-energy nuclear reactions using super low-energy external field
International Nuclear Information System (INIS)
Gareev, F.A.; Zhidkova, I.E.
2006-01-01
We propose a new mechanism of LENR: cooperative processes in the whole system, nuclei + atoms + condensed matter, can occur at a smaller threshold energies than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low-energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution of inner energy of the whole system. (author)
New Cooperative Mechanisms of Low-Energy Nuclear Reactions Using Super Low-Energy External Field
Gareev, F. A.; Zhidkova, I. E.
We propose a new mechanism of LENR: cooperative processes in the whole system, nuclei + atoms + condensed matter, can occur at a smaller threshold energies than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low-energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution of inner energy of the whole system.
Integral of notion for a quantum Sutherland-Calogero system in the external field
International Nuclear Information System (INIS)
Meshcheryakov, D.V.; Tverskoj, V.B.
2000-01-01
The Sutherland-Calogero three-particle system in the external field is considered. The formula for ordering non-commutating variables in the motion integrals is proposed. The motion integrals are obtained in an obvious form. The problem on analytical evidence of the system complete integration by arbitrary N remains open. The formula, proposed in this paper for ordering non-commutating variables in the I n , may be applied by conducting the total evidence [ru
International Nuclear Information System (INIS)
Giovannini, N.
1977-01-01
A complete description of the projective unitary/antiunitary representations of the general covariance group for a charged (relativistic) particle moving in an external (classical), e.m. field is given. This group was derived in a previous paper, independently of any equation of motion, on the basis of some simple physical assumptions. The physical consequences of these results are then discussed and it is shown how they open some new perspectives. (Auth.)
van de Ridder, Bert; Hakvoort, Wouter; van Dijk, Johannes; Lötters, Joost Conrad; de Boer, Andries; Dimitrovova, Z.; de Almeida, J.R.
2013-01-01
In this paper the quantitative influence of external vibrations on the measurement value of a Coriolis Mass-Flow Meter for low flows is investigated, with the eventual goal to reduce the influence of vibrations. Model results are compared with experimental results to improve the knowledge on how
External field-induced chaos in classical and quantum Hamiltonian systems
International Nuclear Information System (INIS)
Lin, W.C.
1986-01-01
Classical nonlinear nonintegrable systems exhibit dense sets of resonance zones in phase space. Global chaotic motion appears when neighboring resonance zones overlap. The chaotic motion signifies the destruction of a quasi constant of motion. The motion of a particle, trapped in one of the wells of a sinusoidal, potential driven by a monochromatic external field was studied. Global chaotic behavior sets in when the amplitude of the external field reaches a critical value. The particle then escapes the well. The critical values are found to be in good agreement with a resonance overlap criterion rather than a renormalization-group scheme. A similar system was then studied, but with the particle being confined in an infinite square well potential instead. A stochastic layer is found in the low-energy part of the phase space. The resonance zone structure is found to be in excellent agreement with predictions. The critical values for the onset of global chaotic behavior are found to be in excellent agreement with the renormalization group scheme. The quantum version of the second model above was then considered. In a similar fashion, the external field induces quantum resonance zones. The spectral statistics were computed, and a transition of statistics from Poissonian to Wigner-like was found as overlap of quantum resonances occurs. This also signifies the destruction of a quasi-constant of motion
Laser generated hot electron transport in an externally applied magnetic field
International Nuclear Information System (INIS)
Burnett, N.H.; Enright, G.D.
1986-01-01
The authors have investigated the effect of an externally applied DC magnetic field on the generation and transport of hot electrons in CO/sub 2/ laser irradiation of cylindrical targets. The targets used in these studies were 6.3 mm diameter metal rods through which a pulsed current was driven from an external capacitor. Magnetic fields up to 150 kgauss were produced at the target surface. The CO/sub 2/ laser was focused with an f/5 lens resulting in a laser intensity of ≅3 x 10/sup 14/ W/cm/sup 2/ in a 100 μm diameter focal spot. The effect of the external magnetic field on the generation and inward transport of superhot (≥ 100 keV) electrons was studied. Principal diagnostics included a six channel hard x-ray spectrometer, a high energy x-ray pinhole camera, a LiF Laue x-ray spectrograph and a Ross-filtered (W-Ta) pair of x-ray detectors. The latter two diagnostics were designed to detect Au Kα /sub emission at 68.2 keV
Electron Raman scattering in semiconductor quantum wire in an external magnetic field
International Nuclear Information System (INIS)
Betancourt-Riera, Ri; Nieto Jalil, J M; Riera, R; Betancourt-Riera, Re; Rosas, R
2008-01-01
The differential cross-section for an electron Raman scattering process in a semiconductor quantum wire in the presence of an external magnetic field perpendicular to the plane of confinement is calculated. We assume a single parabolic conduction band. The emission spectra for different scattering configurations and the selection rules for the processes are studied. Singularities in the spectra are found and interpreted. The electron Raman scattering studied here can be used to provide direct information about the electron band and subband structure of these confinement systems. The magnetic field distribution is considered constant with value B 0 inside the wire and zero outside
Quasi-static electric field in a cylindrical volume conductor induced by external coils.
Esselle, K P; Stuchly, M A
1994-02-01
An expansion technique based on modified Bessel functions is used to obtain an analytical solution for the electric field induced in a homogeneous cylindrical volume conductor by an external coil. The current in the coil is assumed to be changing slowly so that quasi-static conditions can be justified. Valid for any coil type, this solution is ideal for fast computation of the induced electric field at a large number of points. Efficient implementation of this method in a computer code is described and numerical results are presented for a perpendicular circular coil and a tangential double-square coil.
Virtual particle-antiparticle pair formation by a scalar particle bound in an external Coulomb field
International Nuclear Information System (INIS)
Darewych, J.W.; Horbatsch, M.; Lev, B.I.; Shapoval, D.V.
1995-01-01
A Hamiltonian variational Fock-space method is used to describe scalar massive particles in an external Coulomb field with strength f=Zα. The use of an ansatz that includes a three-particle state in addition to a single-particle state built on the field-free vacuum enables one to highlight the role played by particle-antiparticle pair formation. Comparison is made with the Klein-Gordon equation in the Feshbach-Villars representation and it is shown explicitly how the virtual pair contribution corrects an O(f 5 ) deficiency present in the energy spectrum of the naive Schroedinger-type single-particle equation. ((orig.))
International Nuclear Information System (INIS)
Veryaskin, A.V.; Lapchinskij, V.G.; Nekrasov, V.I.; Rubakov, V.A.
1981-01-01
Behaviour of vacuum symmetry in the model of self-acting scalar field in the open and closed isotropic cosmological spaces is investigated. Considered are the cases with the mass squared of the scalar field m 2 >0, m 2 =0 and m 2 2 2 =0 at exponentially large scale factors the study of the problem on the behaviour of the symmetry requires exceeding the limits of the perturbation theory. The final behaviour of the vacuum symmetry in the open model at small radii depends on combined effect of all the external factors [ru
Fractional charges in external field problems and the inverse scattering method
International Nuclear Information System (INIS)
Grosse, H.; Opelt, G.
1986-01-01
Motivated by recent studies of the quantization of fermions interacting with external soliton fields, we construct all reflectionless potentials for the one-dimensional Dirac operator, which are solitons of coupled MKdV equations. The charge of the fermion field in presence of these solitons varies continuously. For the N-soliton solutions it becomes the sum of the charges of the individual problems. The questions of unitary equivalence of representations of the CAR as well as the implementability of gauge transformations are studied for specific examples. (Author)
Energy Technology Data Exchange (ETDEWEB)
Rudolph, E [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany)
1975-01-01
As a model for gravitational radiation damping of a planet the electromagnetic radiation damping of an extended charged body moving in an external gravitational field is calculated in harmonic coordinates using a weak field, slowing-motion approximation. Special attention is paid to the case where this gravitational field is a weak Schwarzschild field. Using Green's function methods for this purpose it is shown that in a slow-motion approximation there is a strange connection between the tail part and the sharp part: radiation reaction terms of the tail part can cancel corresponding terms of the sharp part. Due to this cancelling mechanism the lowest order electromagnetic radiation damping force in an external gravitational field in harmonic coordinates remains the flat space Abraham Lorentz force. It is demonstrated in this simplified model that a naive slow-motion approximation may easily lead to divergent higher order terms. It is shown that this difficulty does not arise up to the considered order.
International Nuclear Information System (INIS)
Lennernaes, B.; Rikner, G.; Letocha, H.; Nilsson, S.
1995-01-01
The purpose of the present study was to identify factors of importance in the planning of external beam radiotherapy of prostatic adenocarcinoma. Seven patients with urogenital cancers were planned for external radiotherapy of the prostate. Four different techniques were used, viz. a 4-field box technique and four-, five- or six-field conformal therapy set-ups combined with three different margins (1-3 cm). The evaluations were based on the doses delivered to the rectum and the urinary bladder. A normal tissue complication probability (NTCP) was calculated for each plan using Lyman's dose volume reduction method. The most important factors that resulted in a decrease of the dose delivered to the rectum and the bladder were the use of conformal therapy and smaller margins. Conformal therapy seemed more important for the dose distribution in the urinary bladder. Five- and six-field set-ups were not significantly better than those with four fields. NTCP calculations were in accordance with the evaluation of the dose volume histograms. To conclude, four-field conformal therapy utilizing reduced margins improves the dose distribution to the rectum and the urinary bladder in the radiotherapy of prostatic adenocarcinoma. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Volkova, T.I., E-mail: tatiana.volkova@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Böhm, V., E-mail: valter.boehm@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Kaufhold, T., E-mail: tobias.kaufhold@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Popp, J., E-mail: jana.popp@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Becker, F., E-mail: felix.becker@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Borin, D.Yu., E-mail: dmitry.borin@tu-dresden.de [Technische Universität Dresden, Magnetofluiddynamics, Measuring and Automation Technology, D-01062 Dresden (Germany); Stepanov, G.V., E-mail: gstepanov@mail.ru [State Institute of Chemistry and Technology of Organoelement Compounds, 105118 Moscow (Russian Federation); Zimmermann, K., E-mail: klaus.zimmermann@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany)
2017-06-01
The development of sensor systems with a complex adaptive regulation of the operating sensitivity and behaviour is an actual scientific and technical challenge. Smart materials like magneto-sensitive elastomers (MSE) are seen as one potential solution for this problem, since their mechanical properties may be controlled by external magnetic fields. The present paper deals with the investigation of elastic and damping properties of MSE containing magnetically soft particles under the influence of a uniform magnetic field. Based on the measurement of the first eigenfrequency of free bending vibrations of a fixed beam, the effective Young's modulus is evaluated theoretically and also numerically using Finite Element Method. It is shown that this parameter, as well as the first eigenfrequency of the beam, increases monotonically with the magnitude of the applied magnetic field. The results are aimed to develop an acceleration sensor with adaptive magnetically controllable sensitivity range for the detection of external mechanical stimuli of the environment. - Highlights: • The motion behaviour of magneto-sensitive elastomers (MSE) with magnetically soft particles is investigated. • The first eigenfrequency of free bending vibrations of an MSE beam can be controlled by a uniform magnetic field. • Based on the experimental results, the effective Young's modulus of the system is evaluated theoretically and numerically. • The Young's modulus increases monotonically with the magnitude of the applied magnetic field. • The controlled mechanical compliance of MSE may be used for development of sensor systems with adaptive sensitivity range.
Coupling behaviors of graphene/SiO2/Si structure with external electric field
Onishi, Koichi; Kirimoto, Kenta; Sun, Yong
2017-02-01
A traveling electric field in surface acoustic wave was introduced into the graphene/SiO2/Si sample in the temperature range of 15 K to 300 K. The coupling behaviors between the sample and the electric field were analyzed using two parameters, the intensity attenuation and time delay of the traveling-wave. The attenuation originates from Joule heat of the moving carriers, and the delay of the traveling-wave was due to electrical resistances of the fixed charge and the moving carriers with low mobility in the sample. The attenuation of the external electric field was observed in both Si crystal and graphene films in the temperature range. A large attenuation around 190 K, which depends on the strength of external electric field, was confirmed for the Si crystal. But, no significant temperature and field dependences of the attenuation in the graphene films were detected. On the other hand, the delay of the traveling-wave due to ionic scattering at low temperature side was observed in the Si crystal, but cannot be detected in the films of the mono-, bi- and penta-layer graphene with high conductivities. Also, it was indicated in this study that skin depth of the graphene film was less than thickness of two graphene atomic layers in the temperature range.
e-e scattering in the presence of an external field
International Nuclear Information System (INIS)
Bergou, J.; Varro, S.; Fedorov, M.V.
1980-08-01
A nonrelativistic treatment is given of electron-electron scattering in the presence of a laser field. The field is accounted for by the external field approximation and is represented by a circularly polarized monochromatic plane-wave field. A simple analytic expression is derived for the transition amplitude which is shown to exhibit internal resonances as well as intensity dependent shifts. The former is the nonrelativistic limit of the resonant Moeller scattering predicted previously by Oleinik (1967a). The latter, however, appears is a higher order of v/c and is consequently negligible for very slow electrons. The differential cross section of the scattering is also given where the effect of the spin and symmetry is taken into account explicitly. The width of resonances is introduced phenomenologically but its connection with previous methods is established. Consideration is also given to the experimental conditions under which the effects may become observable. (author)
Influence of external resonant magnetic perturbation field on edge plasma of small tokamak HYBTOK-II
Energy Technology Data Exchange (ETDEWEB)
Hayashi, Y., E-mail: hayashi-yuki13@ees.nagoya-u.ac.jp [Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Suzuki, Y.; Ohno, N. [Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Okamoto, M. [Ishikawa National College of Technology, Kitachujo, Tsubata-cho, Kahoku-gun, Ishikawa 929-0392 (Japan); Kikuchi, Y. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Sakakibara, S.; Watanabe, K.; Takemura, Y. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan)
2015-08-15
Radial profile of externally applied resonant magnetic perturbation (RMP) field with mode numbers of m = 6 and n = 2 in a small tokamak device HYBTOK-II have been investigated using a magnetic probe array, which is able to measure the radial profile of magnetic field perturbation induced by applying RMP. Results of RMP penetration into the plasma show that the RMP decreased toward the plasma center, while they were amplified around the resonant surface with a safety factor q = 3 due to the formation of magnetic islands. This suggests that RMP fields for controlling edge plasmas may trigger some kind of MHD instabilities. In addition, simulation results, based on a linearized four-field model, which agrees with the experimental ones, indicates that the penetration and amplification process of RMP strongly depend on a Doppler-shifted frequency between the RMP and plasma rotation.
Macroscopic self-consistent model for external-reflection near-field microscopy
International Nuclear Information System (INIS)
Berntsen, S.; Bozhevolnaya, E.; Bozhevolnyi, S.
1993-01-01
The self-consistent macroscopic approach based on the Maxwell equations in two-dimensional geometry is developed to describe tip-surface interaction in external-reflection near-field microscopy. The problem is reduced to a single one-dimensional integral equation in terms of the Fourier components of the field at the plane of the sample surface. This equation is extended to take into account a pointlike scatterer placed on the sample surface. The power of light propagating toward the detector as the fiber mode is expressed by using the self-consistent field at the tip surface. Numerical results for trapezium-shaped tips are presented. The authors show that the sharper tip and the more confined fiber mode result in better resolution of the near-field microscope. Moreover, it is found that the tip-surface distance should not be too small so that better resolution is ensured. 14 refs., 10 figs
Topological phases of silicene and germanene in an external magnetic field: Quantitative results
Singh, Nirpendra; Schwingenschlö gl, Udo
2014-01-01
We investigate the topological phases of silicene and germanene that arise due to the strong spin-orbit interaction in an external perpendicular magnetic field. Below and above a critical field of 10 T, respectively, we demonstrate for silicene under 3% tensile strain quantum spin Hall and quantum anomalous Hall phases. Not far above the critical field, and therefore in the experimentally accessible regime, we obtain an energy gap in the meV range, which shows that the quantum anomalous Hall phase can be realized experimentally in silicene, in contrast to graphene (tiny energy gap) and germanene (enormous field required). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Excitonic magnet in external field: Complex order parameter and spin currents
Geffroy, D.; Hariki, A.; Kuneš, J.
2018-04-01
We investigate spin-triplet exciton condensation in the two-orbital Hubbard model close to half-filling by means of dynamical mean-field theory. Employing an impurity solver that handles complex off-diagonal hybridization functions, we study the behavior of excitonic condensate in stoichiometric and doped systems subject to external magnetic field. We find a general tendency of the triplet order parameter to lie perpendicular with the applied field and identify exceptions from this rule. For solutions exhibiting k -odd spin textures, we discuss the Bloch theorem, which, in the absence of spin-orbit coupling, forbids the appearance of spontaneous net spin current. We demonstrate that the Bloch theorem is not obeyed by the dynamical mean-field theory.
Simulation of a small molecule analogue of a lithium ionomer in an external electric field
Energy Technology Data Exchange (ETDEWEB)
Waters, Sara M.; McCoy, John D., E-mail: mccoy@nmt.edu; Brown, Jonathan R. [Department of Materials Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 (United States); Frischknecht, Amalie L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
2014-01-07
We have investigated the ion dynamics in lithium-neutralized 2-pentylheptanoic acid, a small molecule analogue of a precise poly(ethylene-co-acrylic acid) lithium ionomer. Atomistic molecular dynamics simulations were performed in an external electric field. The electric field causes alignment of the ionic aggregates along the field direction. The energetic response of the system to an imposed oscillating electric field for a wide range of frequencies was tracked by monitoring the coulombic contribution to the energy. The susceptibility found in this manner is a component of the dielectric susceptibility typically measured experimentally. A dynamic transition is found and the frequency associated with this transition varies with temperature in an Arrhenius manner. The transition is observed to be associated with rearrangements of the ionic aggregates.
Behaviour of the order parameter of the simple magnet in an external field
Directory of Open Access Journals (Sweden)
M.P.Kozlovskii
2005-01-01
Full Text Available The effect of a homogeneous external field on the three-dimensional uniaxial magnet behaviour near the critical point is investigated within the framework of the nonperturbative collective variables method using the ρ4 model. The research is carried out for the low-temperature region. The analytic explicit expressions for the free energy, average spin moment and susceptibility are obtained for weak and strong fields in comparison with the field value belonging to the pseudocritical line. The calculations are performed on the microscopic level without any adjusting parameters. It is established that the long-wave fluctuations of the order parameter play a crucial role in forming a crossover between the temperature-dependence and field-dependence critical behaviour of the system.
Topological phases of silicene and germanene in an external magnetic field: Quantitative results
Singh, Nirpendra
2014-03-17
We investigate the topological phases of silicene and germanene that arise due to the strong spin-orbit interaction in an external perpendicular magnetic field. Below and above a critical field of 10 T, respectively, we demonstrate for silicene under 3% tensile strain quantum spin Hall and quantum anomalous Hall phases. Not far above the critical field, and therefore in the experimentally accessible regime, we obtain an energy gap in the meV range, which shows that the quantum anomalous Hall phase can be realized experimentally in silicene, in contrast to graphene (tiny energy gap) and germanene (enormous field required). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
DEFF Research Database (Denmark)
Laitinen, Tommi; Nielsen, Jeppe Majlund; Pivnenko, Sergiy
2004-01-01
An investigation is performed to study the error of the far-field pattern determined from a spherical near-field antenna measurement in the case where a first-order (mu=+-1) probe correction scheme is applied to the near-field signal measured by a higher-order probe.......An investigation is performed to study the error of the far-field pattern determined from a spherical near-field antenna measurement in the case where a first-order (mu=+-1) probe correction scheme is applied to the near-field signal measured by a higher-order probe....
Photovoltaic dependence of photorefractive grating on the externally applied dc electric field
Maurya, M. K.; Yadav, R. A.
2013-04-01
Photovoltaic dependence of photorefractive grating (i.e., space-charge field and phase-shift of the index grating) on the externally applied dc electric field in photovoltaic-photorefractive materials has been investigated. The influence of photovoltaic field (EPhN), diffusion field and carrier concentration ratio r (donor/acceptor impurity concentration ratio) on the space-charge field (SCF) and phase-shift of the index grating in the presence and absence of the externally applied dc electric field have also been studied in details. Our results show that, for a given value of EPhN and r, the magnitude of the SCF and phase-shift of the index grating can be enhanced significantly by employing the lower dc electric field (EONphotovoltaic-photorefractive crystal and higher value of diffusion field (EDN>40). Such an enhancement in the magnitude of the SCF and phase-shift of the index grating are responsible for the strongest beam coupling in photovoltaic-photorefractive materials. This sufficiently strong beam coupling increases the two-beam coupling gain that may be exceed the absorption and reflection losses of the photovoltaic-photorefractive sample, and optical amplification can occur. The higher value of optical amplification in photovoltaic-photorefractive sample is required for the every applications of photorefractive effect so that technology based on the photorefractive effect such as holographic storage devices, optical information processing, acousto-optic tunable filters, gyro-sensors, optical modulators, optical switches, photorefractive-photovoltaic solitons, biomedical applications, and frequency converters could be improved.
International Nuclear Information System (INIS)
Rezaei, Gh.; Shojaeian Kish, S.; Avazpour, A.
2012-01-01
In this article effects of external electric and magnetic fields on the electromagnetically induced transparency of a hydrogenic impurity confined in a two-dimensional quantum dot are investigated. To do this the probe absorption, group velocity and refractive index of the medium in the presence of external electric and magnetic fields are discussed. It is found that, electromagnetically induced transparency occurs in the system and its frequency, transparency window and group velocity of the probe field strongly depend on the external fields. In comparison with atomic system, one may control the electromagnetically induced transparency and the group velocity of light in nano structures with the dot size and confinement potential.
International Nuclear Information System (INIS)
Fu Chuanji; Zhu Qinsheng; Wu Shaoyi
2010-01-01
Based on algebraic dynamics and the concept of the concurrence of the entanglement, we investigate the evolutive properties of the two-qubit entanglement that formed by Heisenberg XXX models under a time-depending external held. For this system, the property of the concurrence that is only dependent on the coupling constant J and total values of the external field is proved. Furthermore, we found that the thermal concurrence of the system under a static random external field is a function of the coupling constant J, temperature T, and the magnitude of external held. (general)
Low energy constituent quark and pion effective couplings in a weak external magnetic field
Braghin, Fábio L.
2018-03-01
An effective model with pions and constituent quarks in the presence of a weak external background electromagnetic field is derived by starting from a dressed one gluon exchange quark-quark interaction. By applying the auxiliary field and background field methods, the structureless pion limit is considered to extract effective pion and constituent quark couplings in the presence of a weak magnetic field. The leading terms of a large quark and gluon masses expansion are obtained by resolving effective coupling constants which turn out to depend on a weak magnetic field. Two pion field definitions are considered for that. Several relations between the effective coupling constants and parameters can be derived exactly or in the limit of very large quark mass at zero and weak constant magnetic field. Among these ratios, the Gell-Mann-Oakes-Renner and the quark level Goldberger-Treiman relations are obtained. In addition to that, in the pion sector, the leading terms of Chiral Perturbation Theory coupled to the electromagnetic field are recovered. Some numerical estimates are provided for the effective coupling constants and parameters.
Quantum entanglement and criticality of the antiferromagnetic Heisenberg model in an external field
International Nuclear Information System (INIS)
Liu Guanghua; Li Ruoyan; Tian Guangshan
2012-01-01
By Lanczos exact diagonalization and the infinite time-evolving block decimation (iTEBD) technique, the two-site entanglement as well as the bipartite entanglement, the ground state energy, the nearest-neighbor correlations, and the magnetization in the antiferromagnetic Heisenberg (AFH) model under an external field are investigated. With increasing external field, the small size system shows some distinct upward magnetization stairsteps, accompanied synchronously with some downward two-site entanglement stairsteps. In the thermodynamic limit, the two-site entanglement, as well as the bipartite entanglement, the ground state energy, the nearest-neighbor correlations, and the magnetization are calculated, and the critical magnetic field h c = 2.0 is determined exactly. Our numerical results show that the quantum entanglement is sensitive to the subtle changing of the ground state, and can be used to describe the magnetization and quantum phase transition. Based on the discontinuous behavior of the first-order derivative of the entanglement entropy and fidelity per site, we think that the quantum phase transition in this model should belong to the second-order category. Furthermore, in the magnon existence region (h < 2.0), a logarithmically divergent behavior of block entanglement which can be described by a free bosonic field theory is observed, and the central charge c is determined to be 1. (paper)
An interacting instanton and anti-instanton system under external color magnetic fields
International Nuclear Information System (INIS)
Wakano, M.
1980-01-01
The equilibrium configurations for the instanton and anti-instanton system of the SU(2) gauge field under constant external color magnetic fields are studied by applying the statistical mechanics method. The vacuum has a stabel equilibrium state in the case where the interaction between pseudoparticles is partly considered through the local gauge field in determining the mean dipole moment of instantons. It is shown, however, that there exists no equilibrium state, either stable or unstable, when the dipolar interaction with a particular instanton-size-dependent cutoff is taken into account directly by the second virial coefficient. To analyze this discrepancy a more general cutoff is introduced and the density of instantons is determined for equilibrium states with vanishing external fields, when the cutoff parameter is varied. Above a certain cutoff length there exist two branches of equilibrium configurations with high or low instanton densities, while below it no equilibrium state is obtained. It is shown that we have a critical cutoff length near but slightly larger than the above value and that the equilibrium states on the lower density branch corresponding to cutoff lengths larger than this critical value are stable, while all remaining equilibrium states are unstable. (orig.)
International Nuclear Information System (INIS)
Pal, Suvajit; Sinha, Sudarson Sekhar; Ganguly, Jayanta; Ghosh, Manas
2013-01-01
Highlights: • The excitation kinetics of impurity doped quantum dot has been investigated. • The dot is subject to Gaussian white noise. • External oscillatory field is also applied. • Noise strength and field intensity fabricate the kinetics. • Role of dopant location has also been analyzed. - Abstract: We investigate the excitation kinetics of a repulsive impurity doped quantum dot initiated by simultaneous application of Gaussian white noise and external sinusoidal field. We have considered both additive and multiplicative noise (in Stratonovich sense). The combined influences of noise strength (ζ) and the field intensity (∊) have been capsuled by invoking their ratio (η). The said ratio and the dopant location have been found to fabricate the kinetics in a delicate way. Moreover, the influences of additive and multiplicative nature of the noise on the excitation kinetics have been observed to be widely different. The investigation reveals emergence of maximization/minimization and saturation in the excitation kinetics as a result of complex interplay between η and the dopant coordinate (r 0 ). The present investigation is believed to provide some useful insights in the functioning of mesoscopic devices where noise plays some significant role
International Nuclear Information System (INIS)
Kikuchi, T.; Kawata, S.; Kawata, S.; Nakajima, M.; Horioka, K.
2006-01-01
Emittance growth due to the transverse focusing field error is investigated during the final beam bunching in the energy driver system of heavy ion inertial fusion. The beam bunch is longitudinally compressed during the transport with the field error in the continuous focusing (CF) or the alternating gradient (AG) field lattices. Numerical calculation results show the only 2% difference of the emittance growth between the cases with and without field error in the CF lattice. In the case of the AG lattice model with the field error of 10%, the emittance growth of 2.4 times is estimated, and the major difference between the CF and AG models is indicated from the numerical simulations. (author)
Coherent cancellation of geometric phase for the OH molecule in external fields
Bhattacharya, M.; Marin, S.; Kleinert, M.
2014-05-01
The OH molecule in its ground state presents a versatile platform for precision measurement and quantum information processing. These applications vitally depend on the accurate measurement of transition energies between the OH levels. Significant sources of systematic errors in these measurements are shifts based on the geometric phase arising from the magnetic and electric fields used for manipulating OH. In this article, we present these geometric phases for fields that vary harmonically in time, as in the Ramsey technique. Our calculation of the phases is exact within the description provided by our recent analytic solution of an effective Stark-Zeeman Hamiltonian for the OH ground state. This Hamiltonian has been shown to model experimental data accurately. We find that the OH geometric phases exhibit rich structure as a function of the field rotation rate. Remarkably, we find rotation rates where the geometric phase accumulated by a specific state is zero, or where the relative geometric phase between two states vanishes. We expect these findings to be of importance to precision experiments on OH involving time-varying fields. More specifically, our analysis quantitatively characterizes an important item in the error budget for precision spectroscopy of ground-state OH.
Canonical field quantization in an external time-dependent gravitational field
International Nuclear Information System (INIS)
Il'yn, S.B.; Tagirov, E.A.
1975-01-01
The Green functions of the quantum scalar fiels interacting with gravitation of the homogeneous isotropic closed Universe are studied. They have been determined as an expectation value of the time-ordered product of two field operators in the cyclic states of various, in general, unitary-nonequivalent representations of canonical commutation relations. The reqularity properties of these functions are shown to be the same as of the Feynman propagator obtained for arbitrary Riemannian space-time only in the representations that from a class unitary equivalence
A Conceptual Design Study for the Error Field Correction Coil Power Supply in JT-60SA
International Nuclear Information System (INIS)
Matsukawa, M.; Shimada, K.; Yamauchi, K.; Gaio, E.; Ferro, A.; Novello, L.
2013-01-01
This paper describes a conceptual design study for the circuit configuration of the Error Field Correction Coil (EFCC) power supply (PS) to maximize the expected performance with reasonable cost in JT-60SA. The EFCC consists of eighteen sector coils installed inside the vacuum vessel, six in the toroidal direction and three in the poloidal direction, each one rated for 30 kA-turn. As a result, star point connection is proposed for each group of six EFCC coils installed cyclically in the toroidal direction for decoupling with poloidal field coils. In addition, a six phase inverter which is capable of controlling each phase current was chosen as PS topology to ensure higher flexibility of operation with reasonable cost.
Analysis of family-wise error rates in statistical parametric mapping using random field theory.
Flandin, Guillaume; Friston, Karl J
2017-11-01
This technical report revisits the analysis of family-wise error rates in statistical parametric mapping-using random field theory-reported in (Eklund et al. []: arXiv 1511.01863). Contrary to the understandable spin that these sorts of analyses attract, a review of their results suggests that they endorse the use of parametric assumptions-and random field theory-in the analysis of functional neuroimaging data. We briefly rehearse the advantages parametric analyses offer over nonparametric alternatives and then unpack the implications of (Eklund et al. []: arXiv 1511.01863) for parametric procedures. Hum Brain Mapp, 2017. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.
Furry picture for quantum electrodynamics with pair-creating external field
International Nuclear Information System (INIS)
Fradkin, E.S.
1981-01-01
The perturbation theory is constructed for QED, for which the interaction with the external pair-creating field is kept exactly. An explicit expression for the perturbation theory causal electron propagator is found. Special features of usage of the unitarity conditions for calculating the total probabilities of radiative processes in the case are discussed. Exact Green functions are introduced and the functional formulation is discussed. Perturbation theory for calculating the mean values of the Heisenberg operators, in particular, of the mean electromagnetic field is built in the case under consideration. Effective Lagrangian which generates the exact equation for the mean electromagnetic field is introduced. Functional representations for the generating functionals introduced in the paper are discussed. (author)
Droplet manipulation by an external electric field for crystalline film growth.
Komino, Takeshi; Kuwabara, Hirokazu; Ikeda, Masaaki; Yahiro, Masayuki; Takimiya, Kazuo; Adachi, Chihaya
2013-07-30
Combining droplet manipulation by the application of an electric field with inkjet printing is proposed as a unique technique to control the surface wettability of substrates for solution-processed organic field-effect transistors (FETs). With the use of this technique, uniform thin films of 2,7-dioctyl[1]benzothieno[2,3,-b][1]benzothiopene (C8-BTBT) could be fabricated on the channels of FET substrates without self-assembled monolayer treatment. High-speed camera observation revealed that the crystals formed at the solid/liquid interface. The coverage of the crystals on the channels depended on the ac frequency of the external electric field applied during film formation, leading to a wide variation in the carrier transport of the films. The highest hole mobility of 0.03 cm(2) V(-1) s(-1) was obtained when the coverage was maximized with an ac frequency of 1 kHz.
Research on external flow field of a car based on reverse engineering
Hu, Shushan; Liu, Ronge
2018-05-01
In this paper, the point cloud data of FAW-VOLKSWAGEN car body shape is obtained by three coordinate measuring instrument and laser scanning method. The accurate three dimensional model of the car is obtained using CATIA software reverse modelling technology. The car body is gridded, the calculation field and boundary condition type of the car flow field are determined, and the numerical simulation is carried out in Hyper Mesh software. The pressure cloud diagram, velocity vector diagram, air resistance coefficient and lift coefficient of the car are obtained. The calculation results reflect the aerodynamic characteristics of the car's external flow field. The motion of the separation flow on the surface of the vehicle body is well simulated, and the area where the vortex motion is relatively intense has been determined. The results provide a theoretical basis for improving and optimizing the body shape.
International Nuclear Information System (INIS)
Carvalho-Santos, Vagson L.; Dandoloff, Rossen
2013-01-01
We study the Heisenberg model in an external magnetic field on curved surfaces with rotational symmetry. The Euler-Lagrange static equations, derived from the Hamiltonian, lead to the inhomogeneous double sine-Gordon equation. Nonetheless, if the magnetic field is coupled to the metric elements of the surface, and consequently to its curvature, the homogeneous double sine-Gordon equation emerges and a 2π-soliton solution is obtained. In order to satisfy the self-dual equations, surface deformations are predicted to appear at the sector where the spin direction is opposite to the magnetic field. On the basis of the model, we find the characteristic length of the 2π-soliton for three specific rotationally symmetric surfaces: the cylinder, the catenoid, and the hyperboloid. On finite surfaces, such as the sphere, torus, and barrels, fractional 2π-solitons are predicted to appear. (author)
Influence of external fields and environment on the dynamics of a phase-qubit-resonator system
International Nuclear Information System (INIS)
Berman, G. P.; Chumak, A. A.
2011-01-01
We analyze the dynamics of a qubit-resonator system coupled with a thermal bath and external electromagnetic fields. Using the evolution equations for the set of Heisenberg operators that describe the whole system, we derive an expression for the resonator field, accounting for the resonator-drive, -bath, and -qubit interaction. The renormalization of the resonator frequency caused by the qubit-resonator interaction is accounted for. Using solutions for the resonator field, we derive the equation describing qubit dynamics. The influence of the qubit evolution during measurement time on the fidelity of a single-shot measurement is studied. The relation between fidelity and measurement time is shown explicitly. Also, an expression describing relaxation of the superposition qubit state toward its stationary value is derived. The possibility of controlling this state by varying the amplitude and frequency of drive is shown.
Enhancement of the thermoelectric figure of merit in a quantum dot due to external ac field
Energy Technology Data Exchange (ETDEWEB)
Chen, Qiao, E-mail: cqhy1127@yahoo.com.cn [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Wang, Zhi-yong, E-mail: wzyong@cqut.edu.cn [School of Optoelectronic Information, Chongqing University of Technology, Chongqing 400054 (China); Xie, Zhong-Xiang [Department of Mathematics and Physics, Hunan Institute of Technology, Hengyang 421002 (China)
2013-08-15
We investigate the figure of merit of a quantum dot (QD) system irradiated with an external microwave filed by nonequilibrium Green's function (NGF) technique. Results show that the frequency of microwave field influence the figure of merit ZT significantly. At low temperature, a sharp peak can be observed in the figure of merit ZT as the frequency of ac field increases. As the frequency varies, several zero points and resonant peaks emerge in the figure of merit ZT. By adjusting the frequency of the microwave field, we can obtain high ZT. The figure of merit ZT increases with the decreasing of linewidth function Γ. In addition, Wiedemann–Franz law does not hold, particularly in the low frequency region due to multi-photon emission and absorption. Some novel thermoelectric properties are also found in two-level QD system.
Sampling Error in Relation to Cyst Nematode Population Density Estimation in Small Field Plots.
Župunski, Vesna; Jevtić, Radivoje; Jokić, Vesna Spasić; Župunski, Ljubica; Lalošević, Mirjana; Ćirić, Mihajlo; Ćurčić, Živko
2017-06-01
Cyst nematodes are serious plant-parasitic pests which could cause severe yield losses and extensive damage. Since there is still very little information about error of population density estimation in small field plots, this study contributes to the broad issue of population density assessment. It was shown that there was no significant difference between cyst counts of five or seven bulk samples taken per each 1-m 2 plot, if average cyst count per examined plot exceeds 75 cysts per 100 g of soil. Goodness of fit of data to probability distribution tested with χ 2 test confirmed a negative binomial distribution of cyst counts for 21 out of 23 plots. The recommended measure of sampling precision of 17% expressed through coefficient of variation ( cv ) was achieved if the plots of 1 m 2 contaminated with more than 90 cysts per 100 g of soil were sampled with 10-core bulk samples taken in five repetitions. If plots were contaminated with less than 75 cysts per 100 g of soil, 10-core bulk samples taken in seven repetitions gave cv higher than 23%. This study indicates that more attention should be paid on estimation of sampling error in experimental field plots to ensure more reliable estimation of population density of cyst nematodes.
Integral equation and simulation studies of a planar nematogenic liquid in crossed external fields
International Nuclear Information System (INIS)
Lado, F; Lomba, E; MartIn, C; Almarza, N G
2005-01-01
We study a fluid of nematogenic molecules with centres of mass constrained to lie in a plane but with axes free to rotate in any direction. An external disorienting field perpendicular to the plane along with a second orienting field in the plane induce an in-plane order-disorder transition. We analyse the behaviour of this simple biaxial model using a well-established generalization of molecular integral equation methods built upon specially tailored basis functions that maintain orthogonality in the presence of anisotropy. Computer simulation and integral equation calculations predict an isotropic-nematic transition at low temperatures in zero field and an in-plane transition at somewhat higher temperatures in the presence of the disorienting field. The oriented states obtained in the presence of both fields can subsequently be used as input to uncover in detail first the transition in the absence of the in-plane orienting field and finally the spontaneous transition in the absence of any field. According to the simulation, the transition apparently belongs to the Berezinskii-Kosterlitz-Thouless defect-mediated type, whereas the theory reproduces a weak first-order transition
Plattner, Alain; Simons, Frederik J.
2017-10-01
When modelling satellite data to recover a global planetary magnetic or gravitational potential field, the method of choice remains their analysis in terms of spherical harmonics. When only regional data are available, or when data quality varies strongly with geographic location, the inversion problem becomes severely ill-posed. In those cases, adopting explicitly local methods is to be preferred over adapting global ones (e.g. by regularization). Here, we develop the theory behind a procedure to invert for planetary potential fields from vector observations collected within a spatially bounded region at varying satellite altitude. Our method relies on the construction of spatiospectrally localized bases of functions that mitigate the noise amplification caused by downward continuation (from the satellite altitude to the source) while balancing the conflicting demands for spatial concentration and spectral limitation. The `altitude-cognizant' gradient vector Slepian functions (AC-GVSF) enjoy a noise tolerance under downward continuation that is much improved relative to the `classical' gradient vector Slepian functions (CL-GVSF), which do not factor satellite altitude into their construction. Furthermore, venturing beyond the realm of their first application, published in a preceding paper, in the present article we extend the theory to being able to handle both internal and external potential-field estimation. Solving simultaneously for internal and external fields under the limitation of regional data availability reduces internal-field artefacts introduced by downward-continuing unmodelled external fields, as we show with numerical examples. We explain our solution strategies on the basis of analytic expressions for the behaviour of the estimation bias and variance of models for which signal and noise are uncorrelated, (essentially) space- and band-limited, and spectrally (almost) white. The AC-GVSF are optimal linear combinations of vector spherical harmonics
Lack of dependence on resonant error field of locked mode island size in ohmic plasmas in DIII-D
La Haye, R. J.; Paz-Soldan, C.; Strait, E. J.
2015-02-01
DIII-D experiments show that fully penetrated resonant n = 1 error field locked modes in ohmic plasmas with safety factor q95 ≳ 3 grow to similar large disruptive size, independent of resonant error field correction. Relatively small resonant (m/n = 2/1) static error fields are shielded in ohmic plasmas by the natural rotation at the electron diamagnetic drift frequency. However, the drag from error fields can lower rotation such that a bifurcation results, from nearly complete shielding to full penetration, i.e., to a driven locked mode island that can induce disruption. Error field correction (EFC) is performed on DIII-D (in ITER relevant shape and safety factor q95 ≳ 3) with either the n = 1 C-coil (no handedness) or the n = 1 I-coil (with ‘dominantly’ resonant field pitch). Despite EFC, which allows significantly lower plasma density (a ‘figure of merit’) before penetration occurs, the resulting saturated islands have similar large size; they differ only in the phase of the locked mode after typically being pulled (by up to 30° toroidally) in the electron diamagnetic drift direction as they grow to saturation. Island amplification and phase shift are explained by a second change-of-state in which the classical tearing index changes from stable to marginal by the presence of the island, which changes the current density profile. The eventual island size is thus governed by the inherent stability and saturation mechanism rather than the driving error field.
Two-electrons quantum dot in plasmas under the external fields
Bahar, M. K.; Soylu, A.
2018-02-01
In this study, for the first time, the combined effects of the external electric field, magnetic field, and confinement frequency on energies of two-electron parabolic quantum dots in Debye and quantum plasmas modeled by more general exponential cosine screened Coulomb (MGECSC) potential are investigated by numerically solving the Schrödinger equation using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in potential. Since the plasma is an important experimental argument for quantum dots, the influence of plasmas modeled by the MGECSC potential on quantum dots is probed. The confinement frequency of quantum dots and the external fields created significant quantum restrictions on quantum dot. In this study, as well as discussion of the functionalities of the quantum restrictions for experimental applications, the parameters are also compared with each other in terms of influence and behaviour. In this manner, the motivation points of this study are summarized as follows: Which parameter can be alternative to which parameter, in terms of experimental applications? Which parameters exhibit similar behaviour? What is the role of plasmas on the corresponding behaviours? In the light of these research studies, it can be said that obtained results and performed discussions would be important in experimental and theoretical research related to plasma physics and/or quantum dots.
Energy Technology Data Exchange (ETDEWEB)
Zhang Longcai [Applied Superconductivity Laboratory, P.O. Box 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: zhlcai2000@163.com; Wang Suyu; Wang Jiasu; Zheng Jun [Applied Superconductivity Laboratory, P.O. Box 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)
2007-12-01
Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.
DEFF Research Database (Denmark)
Martini, Enrica; Breinbjerg, Olav; Maci, Stefano
2006-01-01
A simple and effective procedure for the reduction of truncation error in planar near-field to far-field transformations is presented. The starting point is the consideration that the actual scan plane truncation implies a reliability of the reconstructed plane wave spectrum of the field radiated...
Colored, spinning classical particle in an external non-Abelian gauge field
International Nuclear Information System (INIS)
Arodz, H.
1982-04-01
Classical non-relativistic equations of motion are derived for a colored, spinning point-like particle in an external SU(2) gauge field from Dirac equation. It is found that in addition to the classical spin and color spin vectors, S, I, it is necessary to introduce a new classical dynamical variable [Jsup(ab)], a,b = 1,2,3, describing a mixing of the spin and color. The constraint relations between [Jsup(ab)], S, I are also found. (Auth.)
Numerical study of two dimensional disordered systems in an external magnetic field
International Nuclear Information System (INIS)
Jana, Debnarayan
2000-01-01
We study here 2d tight-binding disordered model in an external magnetic field. By numerically diagonalizing the Hamiltonian, we characterize the eigenstates by Generalized Inverse Participation Ratio (GIPR). The properties of the eigenstates have been studied in case of random flux model as well as with the strength of disorder. Simple theoretical arguments are given in support of the numerical observation. Finally, we have also studied the multifractality of the eigenstates. All these study may shed light on the eigenstates in the center of the band in case of Integer Quantum Hall Effect (IQHE). (author)
Structurization of ferrofluids in the absence of an external magnetic field
International Nuclear Information System (INIS)
Zubarev, A. Yu.; Iskakova, L. Yu.
2013-01-01
Structural transformations in a model ferrofluid in the absence of an external magnetic field have been theoretically studied. The results agree with well-known laboratory experiments and computer simulations in showing that, if the concentration of particles and their magnetic interaction energy are below certain critical values, most particles form separate linear chains. If these parameters exceed the critical values, most particles concentrate so as to form branched network structures. The passage from chains to network has a continuous character rather than represents a discontinuous first-order phase transition.
Pala, M G; Baltazar, S; Martins, F; Hackens, B; Sellier, H; Ouisse, T; Bayot, V; Huant, S
2009-07-01
We study scanning gate microscopy (SGM) in open quantum rings obtained from buried semiconductor InGaAs/InAlAs heterostructures. By performing a theoretical analysis based on the Keldysh-Green function approach we interpret the radial fringes observed in experiments as the effect of randomly distributed charged defects. We associate SGM conductance images with the local density of states (LDOS) of the system. We show that such an association cannot be made with the current density distribution. By varying an external magnetic field we are able to reproduce recursive quasi-classical orbits in LDOS and conductance images, which bear the same periodicity as the Aharonov-Bohm effect.
Transverse kinetics of a charged drop in an external electric field
International Nuclear Information System (INIS)
Bondarenko, S.; Komoshvili, K.
2016-01-01
We investigate a non-equilibrium behavior of a small, dense and charged drop in the transverse plane. A collective motion of the drop’s particles with constant entropy is described. Namely, we solve Vlasov’s equation with non-isotropic initial conditions. Thereby a non-equilibrium distribution function of the process of the droplet evolution in the transverse plane is calculated. An external electric field is included in the initial conditions of the equation that affects on the form of the obtained solution. Applicability of the results to the description of initial states of quark-gluon plasma is also discussed
Transverse kinetics of a charged drop in an external electric field
Energy Technology Data Exchange (ETDEWEB)
Bondarenko, S.; Komoshvili, K. [Ariel University (Israel)
2016-01-22
We investigate a non-equilibrium behavior of a small, dense and charged drop in the transverse plane. A collective motion of the drop’s particles with constant entropy is described. Namely, we solve Vlasov’s equation with non-isotropic initial conditions. Thereby a non-equilibrium distribution function of the process of the droplet evolution in the transverse plane is calculated. An external electric field is included in the initial conditions of the equation that affects on the form of the obtained solution. Applicability of the results to the description of initial states of quark-gluon plasma is also discussed.
Sakai, Munetoshi; Kono, Hiroki; Nakajima, Akira; Sakai, Hideki; Abe, Masahiko; Fujishima, Akira
2010-02-02
On a superhydrophobic surface, the internal fluidity of water droplets with different volumes (15, 30 microL) and their horizontal motion in an external electric field were evaluated using particle image velocimetry (PIV). For driving of water droplets on a superhydrophobic coating between parallel electrodes, it was important to place them at appropriate positions. Droplets moved with slipping. Small droplets showed deformation that is more remarkable. Results show that the dielectrophoretic force induced the initial droplet motion and that the surface potential gradient drove the droplets after reaching the middle point between electrodes.
Encaged molecules in external electric fields: A molecular "tug-of-war"
Gurav, Nalini D.; Gejji, Shridhar P.; Bartolotti, Libero J.; Pathak, Rajeev K.
2016-08-01
Response of polar molecules CH3OH and H2O2 and a non-polar molecule, CO2, as "guests" encapsulated in the dodecahedral water cage (H2O)20 "host," to an external, perturbative electric field is investigated theoretically. We employ the hybrid density-functionals M06-2X and ωB97X-D incorporating the effects of damped dispersion, in conjunction with the maug-cc-pVTZ basis set, amenable for a hydrogen bonding description. While the host cluster (cage) tends to confine the embedded guest molecule through cooperative hydrogen bonding, the applied electric field tends to rupture the cluster-composite by stretching it; these two competitive effects leading to a molecular "tug-of-war." The composite remains stable up to a maximal sustainable threshold electric field, beyond which, concomitant with the vanishing of the HOMO-LUMO gap, the field wins over and the cluster breaks down. The electric-field effects are gauged in terms of the changes in the molecular geometry of the confined species, interaction energy, molecular electrostatic potential surfaces, and frequency shifts of characteristic normal vibrations in the IR regime. Interestingly, beyond the characteristic threshold electric field, the labile, distorted host cluster fragmentizes, and the guest molecule still tethered to a remnant fragment, an effect attributed to the underlying hydrogen-bonded networks.
Structure and viscosity of a transformer oil-based ferrofluid under an external electric field
Energy Technology Data Exchange (ETDEWEB)
Rajnak, M., E-mail: rajnak@saske.sk [Institute of Experimental Physics SAS, Watsonova 47, 04001 Košice (Slovakia); Faculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice (Slovakia); Timko, M.; Kopcansky, P.; Paulovicova, K. [Institute of Experimental Physics SAS, Watsonova 47, 04001 Košice (Slovakia); Tothova, J.; Kurimsky, J.; Dolnik, B.; Cimbala, R. [Faculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice (Slovakia); Avdeev, M.V. [Joint Institute for Nuclear Research, Joliot-Curie 6, Moscow region, 141980 Dubna (Russian Federation); Petrenko, V.I. [Joint Institute for Nuclear Research, Joliot-Curie 6, Moscow region, 141980 Dubna (Russian Federation); Taras Shevchenko Kyiv National University, Volodymyrska Street 64, 01601 Kyiv (Ukraine); Feoktystov, A. [Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching (Germany)
2017-06-01
Various structural changes of ferrofluids have been intensively studied under external magnetic fields. In this work we present an experimental evidence of similar changes induced by an electric field. In the context of the electric field effect on ferrofluids structure, we studied a simple ferrofluid consisting of iron oxide nanoparticles coated with oleic acid and dispersed in transformer oil. The structural changes have been observed both on macroscopic and microscopic scale. We also demonstrate a remarkable impact of the electric field on the ferrofluid viscosity in relation to the reported structural changes. It was found that the electric field induced viscosity changes are analogous to the magnetoviscous effect. These changes and the electroviscous effect are believed to stem from the dielectric permittivity contrast between the iron oxide nanoparticles and transformer oil, giving rise to the effective electric polarization of the nanoparticles. It is highlighted that this electrorheological effect should be considered in studies of ferrofluids for high voltage engineering applications, as it can have impact on the thermomagnetic convection or the dielectric breakdown performance. - Highlights: • An experimental evidence of the electric field induced structural changes in a ferrofluid is presented. • An electroviscous effect in the transformer oil-based ferrofluid is shown. • The dielectric contrast between the particles and the carrier fluid is the key factor. • The potential impact on the thermomagnetic convection of ferrofluids in power transformers is highlighted.
International Nuclear Information System (INIS)
Wilms, D; Virnau, P; Binder, K; Deutschländer, S; Siems, U; Franzrahe, K; Henseler, P; Keim, P; Schwierz, N; Maret, G; Nielaba, P
2012-01-01
In this work, we focus on low-dimensional colloidal model systems, via simulation studies and also some complementary experiments, in order to elucidate the interplay between phase behavior, geometric structures and transport properties. In particular, we try to investigate the (nonlinear!) response of these very soft colloidal systems to various perturbations: uniform and uniaxial pressure, laser fields, shear due to moving boundaries and randomly quenched disorder. We study ordering phenomena on surfaces or in monolayers by Monte Carlo computer simulations of binary hard-disk mixtures, the influence of a substrate being modeled by an external potential. Weak external fields allow a controlled tuning of the miscibility of the mixture. We discuss the laser induced de-mixing for the three different possible couplings to the external potential. The structural behavior of hard spheres interacting with repulsive screened Coulomb or dipolar interaction in 2D and 3D narrow constrictions is investigated using Brownian dynamics simulations. Due to misfits between multiples of the lattice parameter and the channel widths, a variety of ordered and disordered lattice structures have been observed. The resulting local lattice structures and defect probabilities are studied for various cross sections. The influence of a self-organized order within the system is reflected in the velocity of the particles and their diffusive behavior. Additionally, in an experimental system of dipolar colloidal particles confined by gravity on a solid substrate we investigate the effect of pinning on the dynamics of a two-dimensional colloidal liquid. This work contains sections reviewing previous work by the authors as well as new, unpublished results. Among the latter are detailed studies of the phase boundaries of the de-mixing regime in binary systems in external light fields, configurations for shear induced effects at structured walls, studies on the effect of confinement on the structures
Misra, N N; Martynenko, Alex; Chemat, Farid; Paniwnyk, Larysa; Barba, Francisco J; Jambrak, Anet Režek
2018-07-24
Interest in the development and adoption of nonthermal technologies is burgeoning within the food and bioprocess industry, the associated research community, and among the consumers. This is evident from not only the success of some innovative nonthermal technologies at industrial scale, but also from the increasing number of publications dealing with these topics, a growing demand for foods processed by nonthermal technologies and use of natural ingredients. A notable feature of the nonthermal technologies such as cold plasma, electrohydrodynamic processing, pulsed electric fields, and ultrasound is the involvement of external fields, either electric or sound. Therefore, it merits to study the fundamentals of these technologies and the associated phenomenon with a unified approach. In this review, we revisit the fundamental physical and chemical phenomena governing the selected technologies, highlight similarities, and contrasts, describe few successful applications, and finally, identify the gaps in research.
Energy Technology Data Exchange (ETDEWEB)
Gu Chen [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Alamgir, A K M [Faculty of Engineering, Yokohama National University, 75-9 Tokiwadai, Hodogaya-ku, Yokohama (Japan); Qu Timing [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China); Han, Z [Applied Superconductivity Research Center, Tsinghua University, Beijing 100084 (China)
2007-03-15
Ferromagnetic material was electroplated onto the surface of the Bi2223/Ag multi-filamentary tape and as a result changed the I{sub c}(B) characteristic of the tape correspondingly. A numerical simulation was used to investigate the influence of ferromagnetic shielding (FS) on the performance of the tape, in particular the I{sub c} behaviour under perpendicular external fields. Using finite element analysis, we are able to understand how FS alters the flux distribution within the superconductor region under any arbitrary shielding structure. The shielding width, thickness and nonlinear property of the ferromagnetic material were taken into account for the simulation. Finally, optimized shielding parameters in association with different operating fields were suggested and these values could be considered for the next run of experimental work.
International Nuclear Information System (INIS)
Gu Chen; Alamgir, A K M; Qu Timing; Han, Z
2007-01-01
Ferromagnetic material was electroplated onto the surface of the Bi2223/Ag multi-filamentary tape and as a result changed the I c (B) characteristic of the tape correspondingly. A numerical simulation was used to investigate the influence of ferromagnetic shielding (FS) on the performance of the tape, in particular the I c behaviour under perpendicular external fields. Using finite element analysis, we are able to understand how FS alters the flux distribution within the superconductor region under any arbitrary shielding structure. The shielding width, thickness and nonlinear property of the ferromagnetic material were taken into account for the simulation. Finally, optimized shielding parameters in association with different operating fields were suggested and these values could be considered for the next run of experimental work
Entangled plasmon generation in nonlinear spaser system under the action of external magnetic field
Gubin, M. Yu.; Shesterikov, A. V.; Karpov, S. N.; Prokhorov, A. V.
2018-02-01
The present paper theoretically investigates features of quantum dynamics for localized plasmons in three-particle or four-particle spaser systems consisting of metal nanoparticles and semiconductor quantum dots. In the framework of the mean field approximation, the conditions for the observation of stable stationary regimes for single-particle plasmons in spaser systems are revealed, and realization of these regimes is discussed. The strong dipole-dipole interaction between adjacent nanoparticles for the four-particle spaser system is investigated. We show that this interaction can lead to the decreasing of the autocorrelation function values for plasmons. The generation of entangled plasmons in a three-particle spaser system with nonlinear plasmon-exciton interaction is predicted. The use of an external magnetic field is proposed for control of the cross correlations between plasmons in the three-particle spaser system.
International Nuclear Information System (INIS)
Betancourt-Riera, Ri.; Nieto Jalil, J.M.; Betancourt-Riera, Re.; Riera, R.
2009-01-01
The differential cross-section for an electron Raman scattering process in a semiconductor quantum wire in the presence of an external magnetic field perpendicular to the plane of confinement regarding phonon-assisted transitions, is calculated. We assume single parabolic conduction band and present a description of the phonon modes of cylindrical structures embedded in another material using the Froehlich phonon interaction. To illustrate the theory we use a GaAs/Al 0.35 Ga 0.75 As system. The emission spectra are discussed for different scattering configurations and the selection rules for the processes are also studied. The magnetic field distribution is considered constant with value B 0 inside of the wire, and zero outside.
Oscillator representation method in the theory of a hydrogen atom in an external field
International Nuclear Information System (INIS)
Dinejkhan, M.
1996-01-01
The Wick-ordering method called the Oscillator representation in the non-relativistic Schroedinger equation is proposed to calculate the energy spectrum for spherically symmetric and axially symmetric potentials allowing the existence of a bound state. In particular, the method is applied to calculate the energy spectrum of (2s)-states of a hydrogen atom in a uniform magnetic field of an arbitrary strength. In the perturbation (external field) approximation, the energy spectrum of the so-called quadratic and spherical quadratic Zeeman problem and the problem of a hydrogen atom in a generalized van der Waals potential is calculated analytically. The results of the zeroth approximation of oscillator representation are in good agreement with the exact values. 31 refs., 3 tabs
Heat kernel expansion for fermionic billiards in an external magnetic field
International Nuclear Information System (INIS)
Antoine, M.; Comtet, A.; Knecht, M.
1989-05-01
Using Seeley's heat kernel expansion, we compute the asymptotic density of states of the Dirac operator coupled to a magnetic field on a two dimensional manifold with boundary (fermionic billiard). Local boundary conditions compatible with vector current conservation depend on a free parameter α. It is shown that the perimeter correction identically vanishes for α = 0. In that case, the next order constant term is found to be proportional to the Euler characteristic of the manifold. These results are independent of the external magnetic field and of the shape of the billiard, provided the boundary is sufficiently smooth. For the flat circular billiard, the constant term is found to be - 1/12, in agreement with a numerical result by M.V. BERRY and R.J. MONDRAGON (1987)
Influence of external magnetic field on laser-induced gold nanoparticles fragmentation
International Nuclear Information System (INIS)
Serkov, A. A.; Rakov, I. I.; Simakin, A. V.; Kuzmin, P. G.; Shafeev, G. A.; Mikhailova, G. N.; Antonova, L. Kh.; Troitskii, A. V.; Kuzmin, G. P.
2016-01-01
Laser-assisted fragmentation is an efficient method of the nanoparticles size and morphology control. However, its exact mechanisms are still under consideration. One of the remaining problems is the plasma formation, inevitably occurring upon the high intensity laser irradiation. In this Letter, the role of the laser-induced plasma is studied via introduction of high-intensity external magnetic field (up to 7.5 T). Its presence is found to cause the plasma emission to start earlier regarding to a laser pulse, also increasing the plume luminosity. Under these conditions, the acceleration of nanoparticles fragmentation down to a few nanometers is observed. Laser-induced plasma interaction with magnetic field and consequent energy transfer from plasma to nanoparticles are discussed.
Decoupling of the hyperfine interactions in /sup 12/B ions by the external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Sugimoto, K; Tanihata, I; Kogo, S; Tanaka, M [Osaka Univ., Toyonaka (Japan). Faculty of Science
1976-11-01
It is known that product nuclei /sup 12/B (Isup(..pi..) = 1/sup +/, Tsub(1/2) = 20 ms) by the /sup 11/B(d,p)/sup 12/B reaction are sizably oriented if one selects recoil nuclei at the incident deuteron energy and the recoil angle thetasub(R). The hyperfine interactions in recoil ions in flight in free space affect the nuclear orientation. In this experiment, the nuclear orientation in the recoil ions implanted into a stopper were measured as a function of strength of a static magnetic field applied in normal to the reaction plane. A thin single crystal of magnesium was used as the recoil stopper, of which the hexagonal c-axis was set in parallel to the external field.
Population and phase dynamics of F=1 spinor condensates in an external magnetic field
International Nuclear Information System (INIS)
Romano, D.R.; Passos, E.J.V. de
2004-01-01
We show that the classical dynamics underlying the mean-field description of homogeneous mixtures of spinor F=1 Bose-Einstein condensates in an external magnetic field is integrable as a consequence of number conservation and axial symmetry in spin space. The population dynamics depends only on the quadratic term of the Zeeman energy and on the strength of the spin-dependent term of the atom-atom interaction. We determine the equilibrium populations as function of the ratio of these two quantities and the miscibility of the hyperfine components in the ground state spinors are thoroughly discussed. Outside the equilibrium, the populations are always a periodic function of time where the periodic motion can be a libration or a rotation. Our studies also indicate the absence of metastability
A model of the response of GMR of metallic multilayers to external magnetic field
Directory of Open Access Journals (Sweden)
Uba J.I.
2015-12-01
Full Text Available It has not been possible to transform resistivity models in terms of magnetic field in order to account for variation of giant magnetoresistance (GMR with external magnetic field, which would have led to determination of material properties. This problem is approached mathematically via variation calculus to arrive at an exponential function that fits observed GMR values. Using this model in free electron approximation, the mean Fermi vector, susceptibility and total density of states of a number of metallic multilayers are determined from their reported GMR values. Susceptibility is found to depend on interface roughness and antiferromagnetic (AF coupling; thus, it gives qualitative measure of interface quality and AF coupling. Comparison of susceptibilities and GMRs of electrodeposited and ion beam sputtered Co/Cu structures shows that a rough interface suppresses GMR in the former but enhances it in the latter.
External Magnetic Field Reduction Techniques for the Advanced Stirling Radioisotope Generator
Niedra, Janis M.; Geng, Steven M.
2013-01-01
Linear alternators coupled to high efficiency Stirling engines are strong candidates for thermal-to-electric power conversion in space. However, the magnetic field emissions, both AC and DC, of these permanent magnet excited alternators can interfere with sensitive instrumentation onboard a spacecraft. Effective methods to mitigate the AC and DC electromagnetic interference (EMI) from solenoidal type linear alternators (like that used in the Advanced Stirling Convertor) have been developed for potential use in the Advanced Stirling Radioisotope Generator. The methods developed avoid the complexity and extra mass inherent in data extraction from multiple sensors or the use of shielding. This paper discusses these methods, and also provides experimental data obtained during breadboard testing of both AC and DC external magnetic field devices.
Improved linearity using harmonic error rejection in a full-field range imaging system
Payne, Andrew D.; Dorrington, Adrian A.; Cree, Michael J.; Carnegie, Dale A.
2008-02-01
Full field range imaging cameras are used to simultaneously measure the distance for every pixel in a given scene using an intensity modulated illumination source and a gain modulated receiver array. The light is reflected from an object in the scene, and the modulation envelope experiences a phase shift proportional to the target distance. Ideally the waveforms are sinusoidal, allowing the phase, and hence object range, to be determined from four measurements using an arctangent function. In practice these waveforms are often not perfectly sinusoidal, and in some cases square waveforms are instead used to simplify the electronic drive requirements. The waveforms therefore commonly contain odd harmonics which contribute a nonlinear error to the phase determination, and therefore an error in the range measurement. We have developed a unique sampling method to cancel the effect of these harmonics, with the results showing an order of magnitude improvement in the measurement linearity without the need for calibration or lookup tables, while the acquisition time remains unchanged. The technique can be applied to existing range imaging systems without having to change or modify the complex illumination or sensor systems, instead only requiring a change to the signal generation and timing electronics.
Streamwise-body-force-model for rapid simulation combining internal and external flow fields
Directory of Open Access Journals (Sweden)
Cui Rong
2016-10-01
Full Text Available A streamwise-body-force-model (SBFM is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The validation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.
Hadronic Lorentz violation in chiral perturbation theory including the coupling to external fields
Kamand, Rasha; Altschul, Brett; Schindler, Matthias R.
2018-05-01
If any violation of Lorentz symmetry exists in the hadron sector, its ultimate origins must lie at the quark level. We continue the analysis of how the theories at these two levels are connected, using chiral perturbation theory. Considering a 2-flavor quark theory, with dimension-4 operators that break Lorentz symmetry, we derive a low-energy theory of pions and nucleons that is invariant under local chiral transformations and includes the coupling to external fields. The pure meson and baryon sectors, as well as the couplings between them and the couplings to external electromagnetic and weak gauge fields, contain forms of Lorentz violation which depend on linear combinations of quark-level coefficients. In particular, at leading order the electromagnetic couplings depend on the very same combinations as appear in the free particle propagators. This means that observations of electromagnetic processes involving hadrons—such as vacuum Cerenkov radiation, which may be allowed in Lorentz-violating theories—can only reliably constrain certain particular combinations of quark coefficients.
Positioning and aligning CNTs by external magnetic field to assist localised epoxy cure
Directory of Open Access Journals (Sweden)
Ariu G.
2016-01-01
Full Text Available This work focuses on the generation of conductive networks through the localised alignment of nano fillers, such as multi-walled carbon nanotubes (MWCNTs. The feasibility of alignment and positioning of functionalised MWCNTs by external DC magnetic fields was investigated. The aim of this manipulation is to enhance resin curing through AC induction heating due to hysteresis losses from the nanotubes. Experimental analyses focused on in-depth assessment of the nanotube functionalisation, processing and characterisation of magnetic, rheological and cure kinetics properties of the MWCNT solution. The study has shown that an external magnetic field has great potential for positioning and alignment of CNTs. The study demonstrated potential for creating well-ordered architectures with an unprecedented level of control of network geometry. Magnetic characterisation indicated cobalt-plated nanotubes to be the most suitable candidate for magnetic alignment due to their high magnetic sensitivity. Epoxy/metal-plated CNT nanocomposite systems were validated by thermal analysis as induction heating mediums. The curing process could therefore be optimised by the use of dielectric resins. This study offers a first step towards the proof of concept of this technique as a novel repair technology.
Positioning and aligning CNTs by external magnetic field to assist localised epoxy cure
Ariu, G.; Hamerton, I.; Ivanov, D.
2016-01-01
This work focuses on the generation of conductive networks through the localised alignment of nano fillers, such as multi-walled carbon nanotubes (MWCNTs). The feasibility of alignment and positioning of functionalised MWCNTs by external DC magnetic fields was investigated. The aim of this manipulation is to enhance resin curing through AC induction heating due to hysteresis losses from the nanotubes. Experimental analyses focused on in-depth assessment of the nanotube functionalisation, processing and characterisation of magnetic, rheological and cure kinetics properties of the MWCNT solution. The study has shown that an external magnetic field has great potential for positioning and alignment of CNTs. The study demonstrated potential for creating well-ordered architectures with an unprecedented level of control of network geometry. Magnetic characterisation indicated cobalt-plated nanotubes to be the most suitable candidate for magnetic alignment due to their high magnetic sensitivity. Epoxy/metal-plated CNT nanocomposite systems were validated by thermal analysis as induction heating mediums. The curing process could therefore be optimised by the use of dielectric resins. This study offers a first step towards the proof of concept of this technique as a novel repair technology.
Effect of an external electric field on the propagation velocity of premixed flames
Sánchez-Sanz, Mario
2015-01-01
© 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. There have been many experimental investigations into the ability of electric fields to enhance combustion by acting upon ion species present in flames [1]. In this work, we examine this phenomenon using a one-dimensional model of a lean premixed flame under the influence of a longitudinal electric field. We expand upon prior two-step chain-branching reaction laminar models with reactions to model the creation and consumption of both a positively-charged radical species and free electrons. Also included are the electromotive force in the conservation equation for ion species and the electrostatic form of the Maxwell equations in order to resolve ion transport by externally applied and internally induced electric fields. The numerical solution of these equations allows us to compute changes in flame speed due to electric fields. Further, the variation of key kinetic and transport parameters modifies the electrical sensitivity of the flame. From changes in flame speed and reactant profiles we are able to gain novel, valuable insight into how and why combustion can be controlled by electric fields.
Influence of external magnetic field on parameters of surface two-focus spin-wave ferromagnetic lens
International Nuclear Information System (INIS)
Reshetnyak, S.A.; Berezhinskij, A.S.
2012-01-01
The influence of external magnetic field on refraction of surface spin wave propagating through inhomogeneity created in the form of a lens, that is a biaxial ferromagnet placed into uniaxial ferromagnetic medium, is studied.
Guo, Q L; Liang, B L; Wang, Y; Deng, G Y; Jiang, Y H; Zhang, S H; Fu, G S; Simmonds, P J
2014-10-01
The propagation characteristics of a focused laser beam in a SBN:75 photorefractive crystal strongly depend on the signal-to-background intensity ratio (R=Is/Ib) under reverse external electric field. In the range 20>R>0.05, the laser beam shows enhanced self-defocusing behavior with increasing external electric field, while it shows self-focusing in the range 0.03>R>0.01. Spatial solitons are observed under a suitable reverse external electric field for R=0.025. A theoretical model is proposed to explain the experimental observations, which suggest a new type of soliton formation due to "enhancement" not "screening" of the external electrical field.
Hermance, J. F.
1985-01-01
The Earth's magnetic field at MAGSAT altitudes not only has contributions from the Earth's core and static magnetization in the lithosphere, but also from external electric current systems in the ionosphere and magnetosphere, along with induced electric currents flowing in the conducting earth. Hermance assessed these last two contributions; the external time-varying fields and their associated internal counter-parts which are electromagnetically induced. It is readily recognized that during periods of magnetic disturbance, external currents often contribute from 10's to 100's of nanoteslas (gammas) to observations of the Earth's field. Since static anomalies from lithospheric magnetization are of this same magnitude or less, these external source fields must be taken into account when attempting to delineate gross structural features in the crust.
Improved model predictive control of resistive wall modes by error field estimator in EXTRAP T2R
Setiadi, A. C.; Brunsell, P. R.; Frassinetti, L.
2016-12-01
Many implementations of a model-based approach for toroidal plasma have shown better control performance compared to the conventional type of feedback controller. One prerequisite of model-based control is the availability of a control oriented model. This model can be obtained empirically through a systematic procedure called system identification. Such a model is used in this work to design a model predictive controller to stabilize multiple resistive wall modes in EXTRAP T2R reversed-field pinch. Model predictive control is an advanced control method that can optimize the future behaviour of a system. Furthermore, this paper will discuss an additional use of the empirical model which is to estimate the error field in EXTRAP T2R. Two potential methods are discussed that can estimate the error field. The error field estimator is then combined with the model predictive control and yields better radial magnetic field suppression.
Spherical Magnetic Vortex in an External Potential Field: A Dissipative Contraction
Solov'ev, A. A.
2013-09-01
We consider the dissipative evolution of a spherical magnetic vortex with a force-free internal structure, located in a resistive medium and held in equilibrium by the potential external field. The magnetic field inside the sphere is force-free (the model of Chandrasekhar in Proc. Natl. Acad. Sci. 42, 1, 1956). Topologically, it is a set of magnetic toroids enclosed in spherical layers. A new exact MHD solution has been derived, describing a slow, uniform, radial compression of a magnetic spheroid under the pressure of an ambient field, when the plasma density and pressure are growing inside it. There is no dissipation in the potential field outside the sphere, but inside the sphere, where the current density can be high enough, the magnetic energy is continuously converted into heat. Joule dissipation lowers the magnetic pressure inside the sphere, which balances the pressure of the ambient field. This results in radial contraction of the magnetic sphere with a speed defined by the conductivity of the plasma and the characteristic spatial scale of the magnetic field inside the sphere. Formally, the sphere shrinks to zero within a finite time interval (magnetic collapse). The time of compression can be relatively small, within a day, even for a sphere with a radius of about 1 Mm, if the magnetic helicity trapped initially in the sphere (which is proportional to the number of magnetic toroids in the sphere) is quite large. The magnetic system is open along its axis of symmetry. On this axis, the magnetic and electric fields are strictly radial and sign-variable along the radius, so the plasma will be ejected along the axis of magnetic sphere outwards in both directions (as jets) at a rate much higher than the diffusive one, and the charged particles will be accelerated unevenly, in spurts, creating quasi-regular X-ray spikes. The applications of the solution to solar flares are discussed.
International Nuclear Information System (INIS)
Zahnd, G.; Pham, V.T.; Marty, A.; Jamet, M.; Beigné, C.; Notin, L.; Vergnaud, C.; Rortais, F.; Vila, L.; Attané, J.-P.
2016-01-01
We study domain wall injection in 100 nm wide NiFe nanowires, followed by domain wall propagation and pinning on 50 nm wide constrictions. The injection is performed using local and external magnetic fields. Using several nucleation pad geometries, we show that at these small dimensions the use of an external field only does not allow obtaining a reproducible injection/pinning process. However, the use of an additional local field, created by an Oersted line, allows to nucleate a reversed domain at zero external applied field. Then, an external field of 5 mT enables the domain wall to propagate far from the Oersted line, and the pinning occurs reproducibly. We also show that notwithstanding the reproducibility of the pinning process, the depinning field is found to be stochastic, following a bimodal distribution. Using micromagnetic simulation we link two different DW configurations, vortex and transverse, to the two typical depinning fields. - Highlights: • Magnetic domain wall introduction and pinning in Permalloy nanowires with 50 nm wide constrictions. • Magnetic domain nucleation at zero external applied field. • Bimodal distribution of the domain wall configuration in the constriction.
Physical deposition behavior of stiff amphiphilic polyelectrolytes in an external electric field
Hu, Dongmei; Zuo, Chuncheng; Cao, Qianqian; Chen, Hongli
2017-08-01
Coarse-grained molecular dynamics simulations are conducted to study the physical deposition behavior of stiff amphiphilic polyelectrolytes (APEs) in an external electric field. The effects of chain stiffness, the charge distribution of a hydrophilic block, and electric field strength are investigated. Amphiphilic multilayers, which consist of a monolayer of adsorbed hydrophilic monomers (HLMs), a hydrophobic layer, and another hydrophilic layer, are formed in a selective solvent. All cases exhibit locally ordered hydrophilic monolayers. Two kinds of hydrophobic micelles are distinguished based on local structures. Stripe and network hydrophobic patterns are formed in individual cases. Increasing the chain stiffness decreases the thickness of the deposited layer, the lateral size of the hydrophobic micelles, and the amount of deposition. Increasing the number of positively charged HLMs in a single chain has the same effect as increasing chain stiffness. Moreover, when applied normally to the substrate, the electric field compresses the deposited structures and increases the amount of deposition by pulling more PEs toward the substrate. A stronger electric field also facilitates the formation of a thinner and more ordered hydrophilic adsorption layer. These estimates help us explore how to tailor patterned nano-surfaces, nano-interfaces, or amphiphilic nanostructures by physically depositing semi-flexible APEs which is of crucial importance in physical sciences, life sciences and nanotechnology.
International Nuclear Information System (INIS)
Gelis, Francois; Venugopalan, Raju
2006-01-01
We develop a formalism for particle production in a field theory coupled to a strong time-dependent external source. An example of such a theory is the color glass condensate. We derive a formula, in terms of cut vacuum-vacuum Feynman graphs, for the probability of producing a given number of particles. This formula is valid to all orders in the coupling constant. The distribution of multiplicities is non-Poissonian, even in the classical approximation. We investigate an alternative method of calculating the mean multiplicity. At leading order, the average multiplicity can be expressed in terms of retarded solutions of classical equations of motion. We demonstrate that the average multiplicity at next-to-leading order can be formulated as an initial value problem by solving equations of motion for small fluctuation fields with retarded boundary conditions. The variance of the distribution can be calculated in a similar fashion. Our formalism therefore provides a framework to compute from first principles particle production in proton-nucleus and nucleus-nucleus collisions beyond leading order in the coupling constant and to all orders in the source density. We also provide a transparent interpretation (in conventional field theory language) of the well-known Abramovsky-Gribov-Kancheli (AGK) cancellations. Explicit connections are made between the framework for multi-particle production developed here and the framework of reggeon field theory
Energy Technology Data Exchange (ETDEWEB)
Ehsani, M.H., E-mail: Ehsani@semnan.ac.ir [Thin Film Laboratory, Faculty of Physics, Semnan University (Iran, Islamic Republic of); Mehrabad, M. Jalali [Thin Film Laboratory, Faculty of Physics, Semnan University (Iran, Islamic Republic of); Kameli, P. [Department of Physics, Isfahan University of technology, Isfahan 8415683111 (Iran, Islamic Republic of)
2016-11-01
In this work, the external magnetic field effects on growth condition during deposition processes of the Co thin films were studied. Two specimens of Co films with different condition (with and without external magnetic field) were synthesized by pulsed laser deposition method. Structural and magnetic properties of the Co thin films were systematically studied, using atomic force microscope analysis and magnetization measurement, respectively. During the deposition processes, the external applied magnetic field had been provided by a permanent magnet. The experimental results show that the external magnetic field enables one to tune the magnetic properties of the deposited thin films. To clarify this effect, using Multi-Physics COMSOL simulation environment, a study of vapor flux by applied magnetic field during deposition were performed. Comparison between experimental data and output data of the simulation show promising accommodation and approve the existence of a strong correlation between the structural and magnetic properties of the specimens, and deposition rate of Co thin films. - Graphical abstract: Simulation results of the cobalt particles tracing sputtered from the source to substrate with an external magnetic field. Convergence of the particles flux (left) and also the spiral motion of the cobalt particles (right) increase dramatically as they approach the substrate and NdFe35 magnet. - Highlights: • The external magnetic field effects on growth condition during deposition processes of the Co thin films were studied. • Structural and magnetic properties of the Co thin films were systematically studied, using atomic force microscope analysis and magnetization measurement, respectively. • The experimental results show that the external magnetic field enables one to tune the magnetic properties of the deposited thin films. • To clarify this effect, using Multi-Physics COMSOL simulation environment, a study of vapor flux by applied magnetic field
Philippoff, Joanna; Baumgartner, Erin
2016-03-01
The scientific value of citizen-science programs is limited when the data gathered are inconsistent, erroneous, or otherwise unusable. Long-term monitoring studies, such as Our Project In Hawai'i's Intertidal (OPIHI), have clear and consistent procedures and are thus a good model for evaluating the quality of participant data. The purpose of this study was to examine the kinds of errors made by student researchers during OPIHI data collection and factors that increase or decrease the likelihood of these errors. Twenty-four different types of errors were grouped into four broad error categories: missing data, sloppiness, methodological errors, and misidentification errors. "Sloppiness" was the most prevalent error type. Error rates decreased with field trip experience and student age. We suggest strategies to reduce data collection errors applicable to many types of citizen-science projects including emphasizing neat data collection, explicitly addressing and discussing the problems of falsifying data, emphasizing the importance of using standard scientific vocabulary, and giving participants multiple opportunities to practice to build their data collection techniques and skills.
Directory of Open Access Journals (Sweden)
Joanna Philippoff
2015-11-01
Full Text Available The scientific value of citizen-science programs is limited when the data gathered are inconsistent, erroneous, or otherwise unusable. Long-term monitoring studies, such as Our Project In Hawai‘i's Intertidal (OPIHI, have clear and consistent procedures and are thus a good model for evaluating the quality of participant data. The purpose of this study was to examine the kinds of errors made by student researchers during OPIHI data collection and factors that increase or decrease the likelihood of these errors. Twenty-four different types of errors were grouped into four broad error categories: missing data, sloppiness, methodological errors, and misidentification errors. “Sloppiness” was the most prevalent error type. Error rates decreased with field trip experience and student age. We suggest strategies to reduce data collection errors applicable to many types of citizen-science projects including emphasizing neat data collection, explicitly addressing and discussing the problems of falsifying data, emphasizing the importance of using standard scientific vocabulary, and giving participants multiple opportunities to practice to build their data collection techniques and skills.
Development of a new error field correction coil (C-coil) for DIII-D
International Nuclear Information System (INIS)
Robinson, J.I.; Scoville, J.T.
1995-12-01
The C-coil recently installed on the DIII-D tokamak was developed to reduce the error fields created by imperfections in the location and geometry of the existing coils used to confine, heat, and shape the plasma. First results from C-coil experiments include stable operation in a 1.6 MA plasma with a density less than 1.0 x 10 13 cm -3 , nearly a factor of three lower density than that achievable without the C-coil. The C-coil has also been used in magnetic braking of the plasma rotation and high energy particle confinement experiments. The C-coil system consists of six individual saddle coils, each 60 degree wide toroidally, spanning the midplane of the vessel with a vertical height of 1.6 m. The coils are located at a major radius of 3.2 m, just outside of the toroidal field coils. The actual shape and geometry of each coil section varied somewhat from the nominal dimensions due to the large number of obstructions to the desired coil path around the already crowded tokamak. Each coil section consists of four turns of 750 MCM insulated copper cable banded with stainless steel straps within the web of a 3 in. x 3 in. stainless steel angle frame. The C-coil structure was designed to resist peak transient radial forces (up to 1,800 Nm) exerted on the coil by the toroidal and ploidal fields. The coil frames were supported from existing poloidal field coil case brackets, coil studs, and various other structures on the tokamak
Energy Technology Data Exchange (ETDEWEB)
Xu, Ling-Fang; Feng, Xing; Sun, Kang; Liang, Ze-Yu; Xu, Qian; Liang, Jia-Yu; Yang, Chang-Ping [Hubei University, Hubei Key Laboratory of Ferro and Piezoelectric Materials and Devices, Faculty of Physics and Electronic Science, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan (China)
2017-07-15
Sandwich magnetoelectric composites of PZT/NFO/PZT (PNP) have been prepared by laminating PZT5, NiFe{sub 2}O{sub 4}, and PZT5 ceramics in turn with polyvinyl alcohol (PVA) paste. A systematic study of structural, magnetic and ferroelectric properties is undertaken. Structural studies carried out by X-ray diffraction indicate formation of cubic perovskite phase of PZT5 ceramic and cubic spinel phase of NiFe{sub 2}O{sub 4} ceramic. As increasing the content of PZT5 phase, ferroelectric loops and magnetic loops of PNP composites showed increasing remnant electric polarizations and decreasing remnant magnetic moments separately. Both external magnetic fields and bias voltages could regulate the basal radial resonance frequency of the composites, which should be originated with the transformation and coupling of the stress between the piezoelectric phase and magnetostrictive phase. Such magnetoelectric composite provides great opportunities for electrostatically tunable devices. (orig.)
Raymond, C.; Hajj, G.
1994-01-01
We review the problem of separating components of the magnetic field arising from sources in the Earth's core and lithosphere, from those contributions arising external to the Earth, namely ionospheric and magnetospheric fields, in spacecraft measurements of the Earth's magnetic field.
Jin, Jingyu; Song, Dongxing; Geng, Jiafeng; Jing, Dengwei
2018-02-01
Ferrofluids can exhibit the anisotropic thermodynamic properties under magnetic fields. The dynamic optical properties of ferrofluids in the presence of magnetic fields are of particular interest due to their potential application as various optical devices. Although time-dependent light scattering by ferrofluids have been extensively studied, the effect of wavelength of incident light have been rarely considered. Here, for the first time, we investigated both the time- and wavelength-dependent light scattering in water based ferrofluids containing Fe3O4 nanoparticles under an external magnetic field. The field-induced response behavior of the prepared ferrofluid samples was determined and verified first by thermal conductivity measurement and numerical simulation. Double-beam UV-Vis spectrophotometer was employed to record the temporal evolution of transmitted intensity of incident light of various wavelengths passing through the ferrofluid sample and propagating parallel to the applied field. As expected, the light intensity decreases to a certain value right after the field is turned on due to the thermal fluctuation induced disorder inside the flexible particle chains. Then the light intensity further decreases with time until the appearance of a minimum at time τ0 followed by an inversed increase before finally reaches equilibrium at a particular time. More importantly, the characteristic inversion time τ0 was found to follow a power law increase with the wavelength of incident light (τ0 ∼ λα, where α = 2.07). A quantitative explanation for the wavelength dependence of characteristic time was proposed based on the finite-difference time-domain (FDTD) method. The simulation results are in good agreement with our experimental observations. The time-dependent light scattering in ferrofluids under different incident wavelengths was rationalized by considering both the coarsening process of the particle chains and the occurrence of resonance within the
Kink Waves in Non-isothermal Stratified Solar Waveguides: Effect of the External Magnetic Field
Energy Technology Data Exchange (ETDEWEB)
Lopin, I. [Ussuriisk Astrophysical Observatory, Russian Academy of Sciences (Russian Federation); Nagorny, I., E-mail: lopin78@mail.ru [Institute of Automation and Control Processes FEB RAS, Vladivostok (Russian Federation)
2017-10-01
We study the effect of an external magnetic field on the properties of kink waves, propagating along a thin non-isothermal stratified and diverging magnetic flux tube. A wave equation, governing the propagation of kink waves under the adopted model is derived. It is shown that the vertical gradient of temperature introduces a spatially local cut-off frequency ω {sub c}. The vertical distribution of the cut-off frequency is calculated for the reference VAL-C model of the solar atmosphere and for different values of a ratio of external to internal magnetic fields. The results show that the cut-off frequency is negative below the temperature minimum due to the negative temperature gradient. In the chromosphere the cut-off frequency at a given height is smaller for a stronger external magnetic field. For the appropriate range of a ratio B{sub e} / B{sub i} ≈ 0–0.8, the cutoff lies in the range ω{sub c} ≈ 0.003–0.010 s{sup −1} (periods 600 < P{sub c} < 2000 s). The estimate of the cut-off frequency in the transition region is provided as well. In the propagating wave regime, the effective wave energy flux in the non-isothermal diverging flux tubes is the same as in the straight and homogeneous cylindrical waveguides. The obtained wave equation in the limit β = 0 is used to study the kink oscillations of non-isothermal coronal loops. It is found that the gradient of temperature along the coronal loops reduces the frequency ratio of the first overtone to the fundamental mode, i.e., ω{sub 2}/ ω{sub 1} < 2. This reduction grows for a larger ratio of temperature at the loop top to the temperature at the footpoints. Moreover, the effect of reduction is most pronounced for the steeper temperature profiles.
DEFF Research Database (Denmark)
Martini, Enrica; Breinbjerg, Olav; Maci, Stefano
2008-01-01
A simple and effective procedure for the reduction of truncation errors in planar near-field measurements of aperture antennas is presented. The procedure relies on the consideration that, due to the scan plane truncation, the calculated plane wave spectrum of the field radiated by the antenna is...
Local measurement of error field using naturally rotating tearing mode dynamics in EXTRAP T2R
Sweeney, R. M.; Frassinetti, L.; Brunsell, P.; Fridström, R.; Volpe, F. A.
2016-12-01
An error field (EF) detection technique using the amplitude modulation of a naturally rotating tearing mode (TM) is developed and validated in the EXTRAP T2R reversed field pinch. The technique was used to identify intrinsic EFs of m/n = 1/-12, where m and n are the poloidal and toroidal mode numbers. The effect of the EF and of a resonant magnetic perturbation (RMP) on the TM, in particular on amplitude modulation, is modeled with a first-order solution of the modified Rutherford equation. In the experiment, the TM amplitude is measured as a function of the toroidal angle as the TM rotates rapidly in the presence of an unknown EF and a known, deliberately applied RMP. The RMP amplitude is fixed while the toroidal phase is varied from one discharge to the other, completing a full toroidal scan. Using three such scans with different RMP amplitudes, the EF amplitude and phase are inferred from the phases at which the TM amplitude maximizes. The estimated EF amplitude is consistent with other estimates (e.g. based on the best EF-cancelling RMP, resulting in the fastest TM rotation). A passive variant of this technique is also presented, where no RMPs are applied, and the EF phase is deduced.
International Nuclear Information System (INIS)
Yu, Ilchenko M.; Yu, Gorobets O.; Bondar, I.A.; Gaponov, A.M.
2010-01-01
The effect of change of shape of a steel ball was revealed as a result of its etching in an aqueous solution of nitric acid under influence of an external magnetic field. The elongation of a ferromagnetic ball was observed along the direction of an external magnetic field while etching took place uniformly in all the directions without magnetic field application. The steel ball etching in a magnetic field is characterized by formation of three cylindrically symmetric regions with different etching rates and surface structures, divided from each other by clear borders (namely, the pole, equator and transition regions are formed). The non-monotone dependences of etching rate, surface structure of a sample and sample shape after etching on an external magnetic field are observed.
The error analysis of field size variation in pelvis region by using immobilization device
International Nuclear Information System (INIS)
Kim, Ki Hwan; Kang, No Hyun; Kim, Dong Wuk; Kim, Jun Sang; Jang, Ji Young; Kim, Jae Sung; Kim, Yong Eun; Cho, Moon June
2000-01-01
In radiotherapy, it may happen to radiate surrounding normal tissue because of inconsistent field size by changing patient position during treatment. We are going to analyze errors reduced by using immobilization device with Electronic Portal Imaging Device(EPID) in this study. We had treated the twenty-one patients in pelvic region with 10 MV X-ray from Aug. 1998 to Aug. 1999 at chungnam National University Hospital. All patients were treated at supine position during treatment. They were separated to two groups, 11 patients without device and 10 patients with immobilization device. We used styrofoam for immobilization device and measured the error of anterior direction for x, y axis and lateral direction for z, y axis from simulation film to EPID image using matching technique. For no immobilization device group, the mean deviation values of x axis and y axis are 0.19 mm. 0.48 mm, respectively and the standard deviations of systematic deviation are 2.38 mm, 2.19 mm, respectively and of random deviation for x axis and y axis are 1.92 mm. 1.29 mm, respectively. The mean deviation values of z axis and y axis are -3.61 mm. 2.07 mm, respectively and the standard deviations of systematic deviation are 3.20 mm, 2.29 mm, respectively and of random deviation for z axis and y axis are 2.73 mm. 1.62 mm, respectively. For immobilization device group, the mean deviation values of x axis and y axis are 0.71 mm. -1.07 mm, respectively and the standard deviations of systematic deviation are 1.80 mm, 2.26 mm, respectively and the standard deviations of systematic deviation are 1.80 mm, 2.26 mm, respectively of random deviation for x axis and y axis are 1.56 mm. 1.27 mm, respectively. The mean deviation values of z axis and y axis are -1.76 mm. 1.08 mm, respectively and the standard deviations of systematic deviation are 1.87 mm, 2.83 mm, respectively and of random deviation for x axis and y axis are 1.68 mm, 1.65 mm, respectively. Because of reducing random and systematic error
Energy Technology Data Exchange (ETDEWEB)
Buenemann, D
1963-03-15
Some aspects of the theory of longitudinal and transversal waves in a collisionless nonrelativistic plasma are treated. A dispersion relation for multicomponent plasmas is derived from the linearized Boltzmann-Vlasov equation using the full set of Maxwell's equations without an external field. The velocity distributions of the plasma streams are assumed to be Maxwellian. For the particular case of two counterstreaming plasmas it is shown that there exists transversal instabilities for all counterstreaming velocities whereas the well known two stream instabilities only exist for velocities greater than a critical velocity. Exact solutions for the onset of the instabilities can be given. This kind of instability may occur for any nonisotropic velocity distribution in a collisionless plasma. (auth)
Molybdenum oxide nanocolloids prepared by an external field-assisted laser ablation in water
Directory of Open Access Journals (Sweden)
Spadaro Salvatore
2018-01-01
Full Text Available he synthesis of extremely stable molybdenum oxide nanocolloids by pulsed laser ablation was studied. This green technique ensures the formation of contaminant-free nanostructures and the absence of by-products. A focused picosecond pulsed laser beam was used to ablate a solid molybdenum target immersed in deionized water. Molybdenum oxide nearly spherical nanoparticles with dimensions within few nanometers (20-100 nm are synthesized when the ablation processes were carried out, in water, at room temperature and 80°C. The application of an external electric field during the ablation process induces a nanostructures reorganization, as indicated by Scanning-Transmission Electron Microscopy images analysis. The ablation products were also characterized by some spectroscopic techniques: conventional UV-vis optical absorption, atomic absorption, dynamic light scattering, micro-Raman and X-ray photoelectron spectroscopies. Finally, NIH/3T3 mouse fibroblasts were used to evaluate cell viability by the sulforhodamine B assay
Response of SU(2) lattice gauge theory to a gauge invariant external field
International Nuclear Information System (INIS)
Goepfert, M.
1980-10-01
Topologically determined Z(2) variables in pure SU(2) lattice gauge theory are discussed. They count the number of 'vortex souls'. The expectation value of the corresponding Z(2) loop and the dependence of the string tension on an external field h coupled to them is calculated to lowest order in the high temperature expansion. The result is in agreement with the conjecture that the probability distribution of vortex souls determines the string tension. A different formula for the string tension is found in the two limiting cases 0 < /h/ << β << 1 and 0 < β << h << 1. This penomenon is traced to the effect of short range interactions of the vortex souls which are mediated by the other excitations in the theory. (orig.)
Ion acoustic solitary waves in a dusty plasma obliquely propagating to an external magnetic field
International Nuclear Information System (INIS)
Choi, Cheong Rim; Ryu, Chang-Mo; Lee, Nam C.; Lee, D.-Y.
2005-01-01
The nonlinear ion acoustic solitary wave in a magnetized dusty plasma, obliquely propagating to the embedding external magnetic field, is revisited. It is found that when the charge density of dust particles is high, the Sagdeev potential needs to be expanded up to δn 4 near n=1. In this case, it is shown that there could exist rarefactive ion acoustic solitary waves as well as the kink-type double layer solutions, in addition to the conventional hump-type ones found in the δn 3 expansion. The amplitude variations of ion acoustic solitary waves in a magnetized dusty plasma are also examined with respect to the change of the dust charge density and the wave directional angle
The effect of internal and external fields of view on visually induced motion sickness.
Bos, Jelte E; de Vries, Sjoerd C; van Emmerik, Martijn L; Groen, Eric L
2010-07-01
Field of view (FOV) is said to affect visually induced motion sickness. FOV, however, is characterized by an internal setting used by the graphics generator (iFOV) and an external factor determined by screen size and viewing distance (eFOV). We hypothesized that especially the incongruence between iFOV and eFOV would lead to sickness. To that end we used a computer game environment with different iFOV and eFOV settings, and found the opposite effect. We speculate that the relative large differences between iFOV and eFOV used in this experiment caused the discrepancy, as may be explained by assuming an observer model controlling body motion. Copyright 2009 Elsevier Ltd. All rights reserved.
Flux quantization and quantum mechanics on Riemann surfaces in an external magnetic field
International Nuclear Information System (INIS)
Bolte, J.; Steiner, F.
1990-10-01
We investigate the possibility to apply an external constant magnetic field to a quantum mechanical system consisting of a particle moving on a compact or non-compact two-dimensional manifold of constant negative Gaussian curvature and of finite volume. For the motion on compact Riemann surfaces we find that a consistent formulation is only possible if the magnetic flux is quantized, as it is proportional to the (integrated) first Chern class of a certain complex line bundle over the manifold. In the case of non-compact surfaces of finite volume we obtain the striking result that the magnetic flux has to vanish identically due to the theorem that any holomorphic line bundle over a non-compact Riemann surface is holomorphically trivial. (orig.)
Collisional approach to dynamics of resonance atomic states in an external field
International Nuclear Information System (INIS)
Urnov, A.M.; Uskov, D.B.
1993-01-01
The following aspects of the dynamics of an atomic state in an external stationary field are assessed: (i) the rearrangement problem; (ii) the description of the appropriate final-channel wavefunctions; (iii) the analytical properties of the transition amplitude into the continuum. The rearrangement problem was solved by the introduction of the effective Hamiltonian, the eigenstates of which include both the initial state and final states ('modified states of continuum spectrum' MSCS) which describe the potential part of the exact wavefunction of the scattering problem. It is shown that the amplitude of decay and transition into MSCS as functions of time have an exact representation as a sum of resonance terms defined by a set of resonance states and the matrix elements of the shift R-matrix operator. (author)
Prevalence of information stored in arrays of magnetic nanowires against external fields
Ceballos, D.; Cisternas, E.; Vogel, E. E.; Allende, S.
2018-04-01
Arrays of magnetic nanowires in porous alumina can be used to store information inscribed on the system by orienting the magnetization of selected wires pointing in a desired direction, so symbols can be read as ferromagnetic sectors. However, this information is subject to aging and the stored information could be gradually lost. We investigate here two mechanisms proposed to improve the prevalence of the stored information: opposite ferromagnetic band at the center of the symbol and bi-segmented nanowires acting as two layers of nanowires storing the same information. Both mechanisms prove to increase resistance to the action of external magnetic fields for the case of Ni wires in a geometry compatible with actually grown nanowires. Advantages and disadvantages of these mechanisms are discussed.
Martensitic transformations in Ni-Mn-Ga system affected by external fields
International Nuclear Information System (INIS)
Chernenko, V.; Babii, O.; L'vov, V.; McCormick, P.G.
2000-01-01
The influence of hydrostatic pressure, uniaxial stress and magnetic field on the martensitic transformation temperatures for the ferromagnetic single crystalline Ni-Mn-Ga alloys is studied. It is shown that the experimental results are satisfactorily described by the Landau theory. Ni-Mn-Ga L2 1 -type ordered alloys exhibit a number of the first order and weak first order structural transformations in a ferromagnetic or paramagnetic parent phase depending on the alloy composition and being either thermally or stress activated. Most of these phase transformations are of the martensitic type, i.e., they are accompanied by the spontaneous elastic strains forming a multicomponent order parameter in the Landau expansion for the Gibbs potential. In this work we analyze the influence of the external fields (mechanical and magnetic) on the martensitic transformation (MT) from cubic parent phase (P) to five-layered martensitic one (5M-martensite) usually exhibited by the ferromagnetic ordered Ni-Mn-Ga alloys. In accordance with, we treat the 5M-martensite as a twinned tetragonal phase and, so, describe the experimental results in the framework of the theory of cubic-tetragonal MT. The original experimental data of high magnetic field influence on MT in near stoichiometric Ni 2 MnGa compound are presented to compare with the theoretical estimations. (orig.)
Laminar Natural Convection in Square Enclosure Under an Externally Evanescent Magnetic Field
International Nuclear Information System (INIS)
El Jery, Atef; Ben Brahim, Ammar; Magherbi, Mourad
2009-01-01
This paper numerically investigates the effect of an externally evanescent magnetic field on flow patterns and heat transfer of fluid in a square cavity. The horizontal walls of the enclosure are assumed to be insulated while the vertical walls are kept isothermal. A control volume finite element method is used to solve the conservation equations at Prandtl number of 0.71. The effect of constant Hartman number on Nusselt number was studied. Validation tests with existing data demonstrate the aptitude of the present method to produce accurate results. The effects of magnetic field inclination angle from 0 degree to 90 degree on streamlines distributions are shown for different values of Hartman number. For Grashof number equal to 10 5 , the values of relaxation time of the magnetic field are chosen, so that the Lorentz force acts only in the transient state of Nusselt number in natural convection. The Nusselt number was calculated for different values of the inverse relaxation time varying from 0 to + ∞. The magnitude and the number of oscillations of the Nusselt number were observed. It has been found that no oscillation was seen at relaxation time equal to 20
Dependence of Interaction Free Energy between Solutes on an External Electrostatic Field
Directory of Open Access Journals (Sweden)
Pei-Kun Yang
2013-07-01
Full Text Available To explore the athermal effect of an external electrostatic field on the stabilities of protein conformations and the binding affinities of protein-protein/ligand interactions, the dependences of the polar and hydrophobic interactions on the external electrostatic field, −Eext, were studied using molecular dynamics (MD simulations. By decomposing Eext into, along, and perpendicular to the direction formed by the two solutes, the effect of Eext on the interactions between these two solutes can be estimated based on the effects from these two components. Eext was applied along the direction of the electric dipole formed by two solutes with opposite charges. The attractive interaction free energy between these two solutes decreased for solutes treated as point charges. In contrast, the attractive interaction free energy between these two solutes increased, as observed by MD simulations, for Eext = 40 or 60 MV/cm. Eext was applied perpendicular to the direction of the electric dipole formed by these two solutes. The attractive interaction free energy was increased for Eext = 100 MV/cm as a result of dielectric saturation. The force on the solutes along the direction of Eext computed from MD simulations was greater than that estimated from a continuum solvent in which the solutes were treated as point charges. To explore the hydrophobic interactions, Eext was applied to a water cluster containing two neutral solutes. The repulsive force between these solutes was decreased/increased for Eext along/perpendicular to the direction of the electric dipole formed by these two solutes.
Energy Technology Data Exchange (ETDEWEB)
Shi, Wenwu; Wang, Zhiguo, E-mail: zgwang@uestc.edu.cn; Fu, Y.Q., E-mail: richard.fu@northumbria.ac.uk [University of Electronic Science and Technology of China, School of Physical Electronics, Center for Public Security Information and Equipment Integration Technology (China)
2016-11-15
Effects of an external transverse electric field on the adsorption and diffusion of Li atoms on the single-walled carbon nanotubes (CNTs) were investigated using density functional theory. Results showed that the adsorption energy was significantly enhanced by applying the electric field. As the external electric field was increased from 0.0 to 0.6 V/Å, the adsorption energies were decreased from −1.37 to −2.31, −1.32 to −2.46, and −1.33 to −2.63 eV for the Li atoms adsorbed on (6,6), (8,8), and (10,10) CNTs, respectively. Meanwhile, the diffusion barriers of the Li atoms on the CNTs were also decreased as the external electric field was applied. When the external electric field was increased from 0.0 to 0.6 V/Å, the energy barriers were decreased from 0.42, 0.40, and 0.39 eV to 0.20, 0.17, and 0.15 eV for Li diffusion in the (6,6), (8,8), and (10,10) CNTs, respectively. The results proved that an external electric field can be applied to enhance the adsorption and diffusion of Li atoms on the CNTs (used as the anode) for lithium ion batteries.
International Nuclear Information System (INIS)
Shi, Wenwu; Wang, Zhiguo; Fu, Y.Q.
2016-01-01
Effects of an external transverse electric field on the adsorption and diffusion of Li atoms on the single-walled carbon nanotubes (CNTs) were investigated using density functional theory. Results showed that the adsorption energy was significantly enhanced by applying the electric field. As the external electric field was increased from 0.0 to 0.6 V/Å, the adsorption energies were decreased from −1.37 to −2.31, −1.32 to −2.46, and −1.33 to −2.63 eV for the Li atoms adsorbed on (6,6), (8,8), and (10,10) CNTs, respectively. Meanwhile, the diffusion barriers of the Li atoms on the CNTs were also decreased as the external electric field was applied. When the external electric field was increased from 0.0 to 0.6 V/Å, the energy barriers were decreased from 0.42, 0.40, and 0.39 eV to 0.20, 0.17, and 0.15 eV for Li diffusion in the (6,6), (8,8), and (10,10) CNTs, respectively. The results proved that an external electric field can be applied to enhance the adsorption and diffusion of Li atoms on the CNTs (used as the anode) for lithium ion batteries.
International Nuclear Information System (INIS)
Elizalde, E.; Gavrilov, S.P.; Shil'nov, Yu.I.
2000-01-01
A four-fermion model with additional higher-derivative terms is investigated in an external electromagnetic field. The effective potential in the leading order of large-N expansion is calculated in external constant magnetic and electric fields. It is shown that, in contrast to the former results concerning the universal character of 'magnetic catalysis' in dynamical symmetry breaking, in the present higher-derivative model the magnetic field restores chiral symmetry broken initially on the tree level. Numerical results describing a second-order phase transition that accompanies the symmetry restoration at the quantum level are presented. (author)
External electric field driving the ultra-low thermal conductivity of silicene.
Qin, Guangzhao; Qin, Zhenzhen; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming
2017-06-01
The manipulation of thermal transport is in increasing demand as heat transfer plays a critical role in a wide range of practical applications, such as efficient heat dissipation in nanoelectronics and heat conduction hindering in solid-state thermoelectrics. It is well established that the thermal transport in semiconductors and insulators (phonons) can be effectively modulated by structure engineering or materials processing. However, almost all the existing approaches involve altering the original atomic structure of materials, which would be hindered due to either irreversible structure change or limited tunability of thermal conductivity. Motivated by the inherent relationship between phonon behavior and interatomic electrostatic interaction, we comprehensively investigate the effect of external electric field, a widely used gating technique in modern electronics, on the lattice thermal conductivity (κ). Taking two-dimensional silicon (silicene) as a model, we demonstrate that by applying an electric field (E z = 0.5 V Å -1 ) the κ of silicene can be reduced to a record low value of 0.091 W m -1 K -1 , which is more than two orders of magnitude lower than that without an electric field (19.21 W m -1 K -1 ) and is even comparable to that of the best thermal insulation materials. Fundamental insights are gained from observing the electronic structures. With an electric field applied, due to the screened potential resulting from the redistributed charge density, the interactions between silicon atoms are renormalized, leading to phonon renormalization and the modulation of phonon anharmonicity through electron-phonon coupling. Our study paves the way for robustly tuning phonon transport in materials without altering the atomic structure, and would have significant impact on emerging applications, such as thermal management, nanoelectronics and thermoelectrics.
The Dirac equation in external fields: Variable separation in Cartesian coordinates
International Nuclear Information System (INIS)
Shishkin, G.V.; Cabos, W.D.
1991-01-01
The method of separation of variables in the Dirac equation proposed in an earlier work by one of the present authors [J. Math. Phys. 30, 2132 (1989)] is developed for the complete set of interactions of the Dirac particle. The essence of the method consists of the separation of the first-order matrix differential operators that define the dependence of the Dirac bispinor on the related variables, but commutation of such operators with or between the operator of the equation is not assumed. This approach, which is perfectly justified in the presence of gravitational [Theor. Math. Phys. 70, 204 (1987)] or vector fields [J. Math. Phys. 30, 2132 (1989)], permits one to find all the possibilities of separation of variables in the Dirac equation in the case of the most general set of external fields. The complete set of interactions of the Dirac particle is determined by the symmetry group of equations, namely, viz. the SU(4) group. The interactions are scalar, vector, tensor, pseudovector and pseudoscalar. The analysis in this article is limited to Cartesian coordinates. The corresponding results for the general curvilinear coordinates will be presented in a future paper
ZONAL TOROIDAL HARMONIC EXPANSIONS OF EXTERNAL GRAVITATIONAL FIELDS FOR RING-LIKE OBJECTS
Energy Technology Data Exchange (ETDEWEB)
Fukushima, Toshio, E-mail: Toshio.Fukushima@nao.ac.jp [National Astronomical Observatory, Ohsawa, Mitaka, Tokyo 181-8588 (Japan)
2016-08-01
We present an expression of the external gravitational field of a general ring-like object with axial and plane symmetries such as oval toroids or annular disks with an arbitrary density distribution. The main term is the gravitational field of a uniform, infinitely thin ring representing the limit of zero radial width and zero vertical height of the object. The additional term is derived from a zonal toroidal harmonic expansion of a general solution of Laplace’s equation outside the Brillouin toroid of the object. The special functions required are the point value and the first-order derivative of the zonal toroidal harmonics of the first kind, namely, the Legendre function of the first kind of half integer degree and an argument that is not less than unity. We developed a recursive method to compute them from two pairs of seed values explicitly expressed by some complete elliptic integrals. Numerical experiments show that appropriately truncated expansions converge rapidly outside the Brillouin toroid. The truncated expansion can be evaluated so efficiently that, for an oval toroid with an exponentially damping density profile, it is 3000–10,000 times faster than the two-dimensional numerical quadrature. A group of the Fortran 90 programs required in the new method and their sample outputs are available electronically.
First-principles calculation of transport property in nano-devices under an external magnetic field
International Nuclear Information System (INIS)
Chen Jingzhe; Zhang Jin; Han Rushan
2008-01-01
The mesoscopic quantum interference phenomenon (QIP) can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defects, specific QIP is determined by the sample geometry. We have improved a first-principles method based on the matrix Green's function and the density functional theory to simulate the transport behaviour of such systems under a magnetic field. We have studied two kinds of QIP: universal conductance fluctuation (UCF) and Aharonov–Bohm effect (A–B effect). We find that the amplitude of UCF is much smaller than the previous theoretical prediction. We have discussed the origin of difference and concluded that due to the failure of ergodic hypothesis, the ensemble statistics is not applicable, and the conductance fluctuation is determined by the flux-dependent density of states (DOSs). We have also studied the relation between the UCF and the structure of sample. For a specific structure, an atomic circle, the A–B effect is observed and the origin of the oscillation is also discussed
Energy Technology Data Exchange (ETDEWEB)
Huang, Wung-Hong; Du, Yi-Hsien [Department of Physics, National Cheng Kung University,No. 1, University Road, Tainan City 701, Taiwan (China)
2017-02-07
We apply the transformation of mixing azimuthal and internal coordinate or mixing time and internal coordinate to a stack of N black M-branes to find the Melvin spacetime of a stack of N black D-branes with magnetic or electric flux in string theory, after the Kaluza-Klein reduction. We slightly extend previous formulas to investigate the external magnetic and electric effects on the butterfly effect and holographic mutual information. It shows that the Melvin fields do not modify the scrambling time and will enhance the mutual information. In addition, we also T-dualize and twist a stack of N black D-branes to find a Melvin Universe supported by the flux of the NSNS b-field, which describes a non-comutative spacetime. It also shows that the spatial noncommutativity does not modify the scrambling time and will enhance the mutual information. We also study the corrected mutual information in the backreaction geometry due to the shock wave in our three model spacetimes.
Flowing states and vortices in the classical XY model in an external field
International Nuclear Information System (INIS)
Homma, Shigeo; Aoki, Toshizumi; Takeno, Shozo.
1981-01-01
Uniformly flowing states and vortices in the classical XY model in an external field are studied. This is done by using a continuum approximation and by paying attention to particular solutions to nonlinear partial differential equations for two angles theta and phi of rotation of spins for which phi satisfies the Laplace equation. For these two states equations for theta have forms similar to that in the classical Ising model in a transverse field. The uniformly flowing states are therefore described by kink-type excitations identical to those in the two-dimensional Ising model. Phonon modes associated with the uniformly flowing states are also studied, which are similar to Bogoliubov phonons. Vortex solutions and vortex formation energy are studied in close similarity to the case of liquid He 4 . By comparing the energies of these two states, an expression for critical velocity is obtained. By making correspondence to the case of liquid He 4 , numerical values of the critical velocity and of the velocity of phonons around the uniformly flowing states are estimated. For the former the numerical value is in fair agreement with experimental data. (author)
A novel coaxial Ku-band transit radiation oscillator without external guiding magnetic field
Energy Technology Data Exchange (ETDEWEB)
Ling, Junpu, E-mail: lingjunpu@163.com; Zhang, Jiande; He, Juntao; Jiang, Tao [College of Photoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)
2014-02-15
A novel coaxial transit radiation oscillator without external guiding magnetic field is designed to generate high power microwave at Ku-band. By using a coaxial structure, the space-charge potential energy is suppressed significantly, that is good for enhancing efficient beam-wave interaction. In order to improve the transmission stability of the unmagnetized intense relativistic electron beam, a Pierce-like cathode is employed in the novel device. By contrast with conventional relativistic microwave generators, this kind of device has the advantages of high stability, non-guiding magnetic field, and high efficiency. Moreover, with the coaxial design, it is possible to improve the power-handing capacity by increasing the radial dimension of the Ku-band device. With a 550 keV and 7.5 kA electron beam, a 1.25 GW microwave pulse at 12.08 GHz has been obtained in the simulation. The power conversion efficiency is about 30%.
Measurement of dipole-moment in atomic transitions under strong external magnetic field
International Nuclear Information System (INIS)
Nittoh, Koichi; Kuwako, Akira; Ikehara, Tadashi; Yoshida, Tadashi; Watanabe, Takasi; Yoguchi, Itaru; Suzuki, Kazuhiro.
1996-01-01
Obtaining an accurate value of the electric dipole moment μ is essential in the fields of laser application technologies. A direct way of measuring the electric dipole moment μ is to observe the Rabi-oscillation which manifests itself in the coherent photo-excitation behavior of atoms. In the case of the elements which have large angular momenta, identifying the Rabi-oscillation in their excitation behavior becomes rather difficult. We proposed an accurate and straightforward method of determining the electric-dipole moment μ between multi-fold degenerate levels. The point is to remove the degeneracy by applying an external magnetic field with the aid of the Zeeman effect and, then, to realize a degeneration free coherent excitation. As a result, we can observe the Rabi-oscillations explicitly in the excitation υs. laser-fluence curves. The present method provides a reliable basis of experimental determination of μ. As an example, we applied the present method to a transition to 0-17,362 cm -1 level in uranium and obtained the value μ=0.86±0.06 (Debye). (author)
Review of the Elementary Particles Physics in the External Electromagnetic Fields Studies at KEK
Konstantinova, O. Tanaka
2017-03-01
High Energy Accelerator Research Organization (KEK [1]) is a world class accelerator-based research laboratory. The field of its scientific interests spreads widely from the study of fundamental properties of matter, particle physics, nuclear physics to materials science, life science, technical researches, and industrial applications. Research outcomes from the laboratory achieved making use of high-energy particle beams and synchrotron radiation. Two synchrotron facilities of KEK, the Photon Factory (PF) ring and the Photon Factory Advanced Ring (PF-AR) are the second biggest synchrotron light source in Japan. A very wide range of the radiated light, from visible light to X-ray, is provided for a variety of materials science, biology, and life science [2]. KEK strives to work closely with national and international research institutions, promoting collaborative research activities. Advanced research and facilities provision are key factors to be at the frontier of the accelerator science. In this review I am going to discuss KEK overall accelerator-based science, and to consider light sources research and development. The state of arts of the current projects with respect to the elementary particles physics in the external electromagnetic fields is also stressed here.
Hu, Qing-Qing; Freier, Christian; Leykauf, Bastian; Schkolnik, Vladimir; Yang, Jun; Krutzik, Markus; Peters, Achim
2017-09-01
Precisely evaluating the systematic error induced by the quadratic Zeeman effect is important for developing atom interferometer gravimeters aiming at an accuracy in the μ Gal regime (1 μ Gal =10-8m /s2 ≈10-9g ). This paper reports on the experimental investigation of Raman spectroscopy-based magnetic field measurements and the evaluation of the systematic error in the gravimetric atom interferometer (GAIN) due to quadratic Zeeman effect. We discuss Raman duration and frequency step-size-dependent magnetic field measurement uncertainty, present vector light shift and tensor light shift induced magnetic field measurement offset, and map the absolute magnetic field inside the interferometer chamber of GAIN with an uncertainty of 0.72 nT and a spatial resolution of 12.8 mm. We evaluate the quadratic Zeeman-effect-induced gravity measurement error in GAIN as 2.04 μ Gal . The methods shown in this paper are important for precisely mapping the absolute magnetic field in vacuum and reducing the quadratic Zeeman-effect-induced systematic error in Raman transition-based precision measurements, such as atomic interferometer gravimeters.
International Nuclear Information System (INIS)
Kartashov, I. N.; Kuzelev, M. V.
2014-01-01
Electromagnetic modes of a plasma waveguide with a nonsimply connected cross section in an external magnetic field are investigated. The existence of quasi-TEM modes in a finite-strength magnetic field is demonstrated. It is shown that, in the limits of infinitely strong and zero magnetic fields, this mode transforms into a true TEM mode. The possibility of excitation of such modes by an electron beam in the regime of the anomalous Doppler effect is analyzed
Colloidal dispersions in external fields: from equilibrium to non-equilibrium
Lowen, Hartmut
2010-03-01
Dispersions of colloidal particles are excellent model systems of classical statistical mechanics in order to understand the principles of self-organization processes. Using an external field (e.g. electric or magnetic field) the effective interaction between the colloidal particles can be tailored and the system can be brought into non-equilibrium in a controlled way. Glass formation after an ultrafast quench in a two-dimensional superparamagnetic binary colloidal mixture [1,2] will be discussed as well as lane [3,4,5,6,7] and band [8] formation in mixtures of charged suspensions and dusty plasmas driven by an electric field. [4pt] References:[0pt] [1] L. Assoud, F. Ebert, P. Keim, R. Messina, G. Maret, H. Lowen, Phys. Rev. Letters 102, 238301 (2009). [0pt] [2] L. Assoud, F. Ebert, P. Keim, R. Messina, G. Maret, H. Lowen, J. Phys.: Condensed Matter 21, 464114 (2009). [0pt] [3] J. Dzubiella, G. P. Hoffmann, H. Lowen, Phys. Rev. E 65, 021402 (1-8) (2002). [0pt] [4] M. E. Leunissen, C. G. Christova, A. P. Hynninen, C. P. Royall, A. I. Campbell, A. Imhof, M. Dijkstra, R. van Roij, A. van Blaaderen, Nature 437, 235 (2005). [0pt] [5] M. Rex, H. Lowen, Phys. Rev. E 75, 051402 (2007). [0pt] [6] M. Rex, C. P. Royall, A. van Blaaderen, H. Lowen, Lane formation in driven colloidal mixtures: is it continuous or discontinuous?, http://arxiv.org/abs/0812.0908 [0pt] [7] K. R. Sutterlin, A. Wysocki, A. V. Ivlev, C. Rath, H. M. Thomas, M. Rubin-Zuzic, W. J. Goedheer, V. E. Fortov, A. M. Lipaev, V. I. Molotkov, O. F. Petrov, G. E. Morfill, H. Lowen, Phys. Rev. Letters 102, 085003 (2009). [0pt] [8] A. Wysocki, H. Lowen, Phys. Rev. E 79, 041408 (2009).
International Nuclear Information System (INIS)
Mostrom, M.A.
1979-01-01
Coaxial transmission lines, used to transfer the high voltage pulse into the diode region of a relativistic electron beam generator, have been studied using the two-dimensional time-dependent fully relativistic and electromagnetic particle simulation code CCUBE. A simple theory of magnetic insulation that agrees well with simulation results for a straight cylindrical coax in a uniform external magnetic field is used to interpret the effects of anode--cathode shaping and nonuniform external magnetic fields. Loss of magnetic insulation appears to be minimized by satisfying two conditions: (1) the cathode surface should follow a flux surface of the external magnetic field; (2) the anode should then be shaped to insure that the magnetic insulation impedance, including transients, is always greater than the effective load impedance wherever there is an electron flow in the anode--cathode gap
International Nuclear Information System (INIS)
Vysotsky, V.S.; Takayasu, M.; Minervini, J.V.
1997-01-01
A new method has been developed to study Ramp Rate Limitation (RRL) phenomena. Samples of ITER-type cable-in-conduit (CICC) subcable were instrumented with local field sensors such as Hall probes and pick-up coils and then subjected to rapidly changing external magnetic field. The authors found that during fast field sweeps some discontinuous changes, or jumps occur in the local field. They believe that these jumps indicate a fast current redistribution processes inside CICC. Detailed information about local magnetic field jumps during changing field is presented. Possible origin of the jumps and their connection with RRL are discussed
Directory of Open Access Journals (Sweden)
B. Torres
2013-08-01
Full Text Available Sensitivity studies indicate that among the diverse error sources of ground-based sky radiometer observations, the pointing error plays an important role in the correct retrieval of aerosol properties. The accurate pointing is specially critical for the characterization of desert dust aerosol. The present work relies on the analysis of two new measurement procedures (cross and matrix specifically designed for the evaluation of the pointing error in the standard instrument of the Aerosol Robotic Network (AERONET, the Cimel CE-318 Sun photometer. The first part of the analysis contains a preliminary study whose results conclude on the need of a Sun movement correction for an accurate evaluation of the pointing error from both new measurements. Once this correction is applied, both measurements show equivalent results with differences under 0.01° in the pointing error estimations. The second part of the analysis includes the incorporation of the cross procedure in the AERONET routine measurement protocol in order to monitor the pointing error in field instruments. The pointing error was evaluated using the data collected for more than a year, in 7 Sun photometers belonging to AERONET sites. The registered pointing error values were generally smaller than 0.1°, though in some instruments values up to 0.3° have been observed. Moreover, the pointing error analysis shows that this measurement can be useful to detect mechanical problems in the robots or dirtiness in the 4-quadrant detector used to track the Sun. Specifically, these mechanical faults can be detected due to the stable behavior of the values over time and vs. the solar zenith angle. Finally, the matrix procedure can be used to derive the value of the solid view angle of the instruments. The methodology has been implemented and applied for the characterization of 5 Sun photometers. To validate the method, a comparison with solid angles obtained from the vicarious calibration method was
International Nuclear Information System (INIS)
Guo, Xiaoyong; Ren, Xiaobin; Wang, Gangzhi; Peng, Jie
2014-01-01
We investigate the impact of a time-reversal invariant external field on the topological phases of a three-dimensional (3D) topological insulator. By taking the momentum k z as a parameter, we calculate the spin-Chern number analytically. It is shown that both the quantum spin Hall phase and the integer quantum Hall phase can be realized in our system. When the strength of the external field is varied, a series of topological phase transitions occurs with the closing of the energy gap or the spin-spectrum gap. In a tight-binding form, the surface modes are discussed numerically to confirm the analytically results. (paper)
International Nuclear Information System (INIS)
Afanas'ev, G.N.; Stepanovskij, Yu.P.
1994-01-01
We investigate how the choice of the magnetization distribution inside the sample affects its interaction with the external electromagnetic field. The strong selectivity to the time dependence of the external electromagnetic field arises for the particular magnetizations. This can be used for the storage and ciphering of information. We propose a time-dependent Aharonov-Bohm-like experiment in which the phase of the wave function is changed by the time-dependent vector magnetic potential. The arising time-dependent interference picture may be viewed as a new channel for the information transfer. 15 refs., 4 figs
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Rindani, S.D.
1989-03-01
A gauge-invariant theory of a massive spin-3/2 particle interaction with external electromagnetic and gravitational fields, obtained earlier by Kaluza-Klein reduction of a massless Rarita-Schwinger theory, is quantized using Dirac's procedure. The field anticommutators are found to be positive definite. The theory, which was earlier shown to be free from the classical Velo-Zwanziger problem of noncausal propagation modes, is thus also free from the problem of negative-norm states, a long-standing problem associated with massive spin-3/2 theories with external interaction. (author). 19 refs
Error Analysis and Calibration Method of a Multiple Field-of-View Navigation System.
Shi, Shuai; Zhao, Kaichun; You, Zheng; Ouyang, Chenguang; Cao, Yongkui; Wang, Zhenzhou
2017-03-22
The Multiple Field-of-view Navigation System (MFNS) is a spacecraft subsystem built to realize the autonomous navigation of the Spacecraft Inside Tiangong Space Station. This paper introduces the basics of the MFNS, including its architecture, mathematical model and analysis, and numerical simulation of system errors. According to the performance requirement of the MFNS, the calibration of both intrinsic and extrinsic parameters of the system is assumed to be essential and pivotal. Hence, a novel method based on the geometrical constraints in object space, called checkerboard-fixed post-processing calibration (CPC), is proposed to solve the problem of simultaneously obtaining the intrinsic parameters of the cameras integrated in the MFNS and the transformation between the MFNS coordinate and the cameras' coordinates. This method utilizes a two-axis turntable and a prior alignment of the coordinates is needed. Theoretical derivation and practical operation of the CPC method are introduced. The calibration experiment results of the MFNS indicate that the extrinsic parameter accuracy of the CPC reaches 0.1° for each Euler angle and 0.6 mm for each position vector component (1σ). A navigation experiment verifies the calibration result and the performance of the MFNS. The MFNS is found to work properly, and the accuracy of the position vector components and Euler angle reaches 1.82 mm and 0.17° (1σ) respectively. The basic mechanism of the MFNS may be utilized as a reference for the design and analysis of multiple-camera systems. Moreover, the calibration method proposed has practical value for its convenience for use and potential for integration into a toolkit.
Reducing errors benefits the field-based learning of a fundamental movement skill in children.
Capio, C M; Poolton, J M; Sit, C H P; Holmstrom, M; Masters, R S W
2013-03-01
Proficient fundamental movement skills (FMS) are believed to form the basis of more complex movement patterns in sports. This study examined the development of the FMS of overhand throwing in children through either an error-reduced (ER) or error-strewn (ES) training program. Students (n = 216), aged 8-12 years (M = 9.16, SD = 0.96), practiced overhand throwing in either a program that reduced errors during practice (ER) or one that was ES. ER program reduced errors by incrementally raising the task difficulty, while the ES program had an incremental lowering of task difficulty. Process-oriented assessment of throwing movement form (Test of Gross Motor Development-2) and product-oriented assessment of throwing accuracy (absolute error) were performed. Changes in performance were examined among children in the upper and lower quartiles of the pretest throwing accuracy scores. ER training participants showed greater gains in movement form and accuracy, and performed throwing more effectively with a concurrent secondary cognitive task. Movement form improved among girls, while throwing accuracy improved among children with low ability. Reduced performance errors in FMS training resulted in greater learning than a program that did not restrict errors. Reduced cognitive processing costs (effective dual-task performance) associated with such approach suggest its potential benefits for children with developmental conditions. © 2011 John Wiley & Sons A/S.
International Nuclear Information System (INIS)
McDonald, D.W.
1977-01-01
Thermocouples with ferromagnetic thermoelements (iron, Alumel, Nisil) are used extensively in industry. We have observed the generation of voltage spikes within ferromagnetic wires when the wires are placed in an alternating magnetic field. This effect has implications for thermocouple thermometry, where it was first observed. For example, the voltage generated by this phenomenon will contaminate the thermocouple thermal emf, resulting in temperature measurement error
International Nuclear Information System (INIS)
Kondic, N.; Jacobs, A.; Ebert, D.
1983-01-01
In many fields one needs to know the spatial density distribution; two-phase systems are of particular importance. In particular, gas-liquid mixtures play a role in power generation, chemistry, bio-medicine etc. An intrusion into the measured system is frequently undesired or not permitted. Therefore, external, non-invasive instrumentation has definite advantages. Photon-energy discrimination methods, measuring scattered fluxes, can employ stationary equipment; they need partial collimation or only protective shielding. The results are achieved with a higher information/irradiation ratio than is the case with transmission methods. The utilization a mesh of isogonic lines (each of them being characterised by its particular scattering angle) has several advantages when compared with the mesh of straight lines (''pencil beams'') used in tomography. The ultimate experimental arrangement employing Compton scattering has fan/fan beam geometry, i.e., wide angle emitting and receiving of gammas. The direct result of the measurement is a ''scattergram'', i.e., countrate versus scattered energy spectrum. Besides representing the ''signature'' of a two- or three-dimensional density distribution, it also enables the reconstruction of local density values. The report outlines the necessary analysis and presents experimental proof of principle
Rodriguez Lucatero, C.; Schaum, A.; Alarcon Ramos, L.; Bernal-Jaquez, R.
2014-07-01
In this study, the dynamics of decisions in complex networks subject to external fields are studied within a Markov process framework using nonlinear dynamical systems theory. A mathematical discrete-time model is derived using a set of basic assumptions regarding the convincement mechanisms associated with two competing opinions. The model is analyzed with respect to the multiplicity of critical points and the stability of extinction states. Sufficient conditions for extinction are derived in terms of the convincement probabilities and the maximum eigenvalues of the associated connectivity matrices. The influences of exogenous (e.g., mass media-based) effects on decision behavior are analyzed qualitatively. The current analysis predicts: (i) the presence of fixed-point multiplicity (with a maximum number of four different fixed points), multi-stability, and sensitivity with respect to the process parameters; and (ii) the bounded but significant impact of exogenous perturbations on the decision behavior. These predictions were verified using a set of numerical simulations based on a scale-free network topology.
The IBM-5C stationary in source without an external magnetic field
International Nuclear Information System (INIS)
Kulygin, V.M.; Malakhov, N.P.; Panasenkov, A.A.; Pleshivtsev, N.V.; Romanov, V.I.; Semashko, N.N.; Seregin, V.S.; Chukhin, I.A.; Shmeleva, V.I.
1982-01-01
With the purpose of constructing efficient injectors of hydrogen fast atoms for plasma heating in magnetic traps problems arising in the course of creation of stationary high-current ion sources and specific methods of solution of these problems are considered. The design and characteristics of the YVM-50 stationary ion source without an external magnetic field intended for obtaining hydrogen ion beams with energy up to 40 keV, current 30 A and pulse duration over 2 sec. are described. Thermal regime of ion source direct heating cathode is considered. It is shown that the lanthanum hexaboride cathode at the temperature 1700 deg C ensures 30 A/cm 2 emission density radiating about 60 W/cm 2 . YBM-5c consists of a gas-discharge chamber (GDC) and ion-optical system (IOS). GDS is composed of a cathode unit, anode flange, casing, gas supply system, IOS consists of emission accelerating and earthed electrodes. At the discharge pulse duration less than 1 sec. current emission density attains 0,5 A/cm 2 which permits to extract from the ion source 30 A current beam. The ion source operation in complex with a high-voltage supply system has shown that one of the most important problems is reliability of high-voltage protection from break-downs and stability of modulators operation
Anomalous behavior of a confined two-dimensional electron within an external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Rosas, R; Riera R; Marin, J. L. [Universidad de Sonora, Hermosillo, Sonora (Mexico); Leon, H. [Instituto Superior Jose Antonio Echeverria, La Habana (Cuba)
2001-10-01
An anomalous diamagnetic behavior of a confined two-dimensional electron within an external magnetic field (perpendicular to the confining plane) is discussed in this letter. Although this finding is consistent with the pioneering work of Robnik, it has not been previously reported. When this effect occurs, the ratio between the typical length of spatial and magnetic confinement is an integer number. This property leads also to a quantization of the magnetic flux across the confining circle. The possible consequences of the peculiar behavior of the electron within such a structure are discussed. [Spanish] Se estudia una posible anomalia en las propiedades diamagneticas de un electron bidimensional confinado en presencia de un campo magnetico externo perpendicular al plano de confinamiento. Aunque los resultados obtenidos son consistentes con el trabajo pionero de Robnik, no han sido reportados anteriormente, a pesar de sus posibles aplicaciones, ya que cuando ocurre, el cociente entre la longitud magnetica y el tamano de la region de confinamiento es un numero entero, propiedad que establece una cuantizacion del flujo magnetico que atraviesa el circulo confinante. Se discuten las posibles consecuencias del comportamiento peculiar del electron en este tipo de estructura.
Linear response and correlation of a self-propelled particle in the presence of external fields
Caprini, Lorenzo; Marini Bettolo Marconi, Umberto; Vulpiani, Angelo
2018-03-01
We study the non-equilibrium properties of non interacting active Ornstein-Uhlenbeck particles (AOUP) subject to an external nonuniform field using a Fokker-Planck approach with a focus on the linear response and time-correlation functions. In particular, we compare different methods to compute these functions including the unified colored noise approximation (UCNA). The AOUP model, described by the position of the particle and the active force acting on it, is usually mapped into a Markovian process, describing the motion of a fictitious passive particle in terms of its position and velocity, where the effect of the activity is transferred into a position-dependent friction. We show that the form of the response function of the AOUP depends on whether we put the perturbation on the position and keep unperturbed the active force in the original variables or perturb the position and maintain unperturbed the velocity in the transformed variables. Indeed, as a result of the change of variables the perturbation on the position becomes a perturbation both on the position and on the fictitious velocity. We test these predictions by considering the response for three types of convex potentials: quadratic, quartic and double-well potential. Moreover, by comparing the response of the AOUP model with the corresponding response of the UCNA model we conclude that although the stationary properties are fairly well approximated by the UCNA, the non equilibrium properties are not, an effect which is not negligible when the persistence time is large.
Energy Technology Data Exchange (ETDEWEB)
Cavalcanti, E.; Castro, E.; Malbouisson, A.P.C. [Centro Brasileiro de Pesquisas Fisicas/MCTI, Rio de Janeiro, RJ (Brazil); Linhares, C.A. [Universidade do Estado do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, RJ (Brazil)
2017-10-15
A scalar model is built, as a quantum field theory defined on a toroidal topology, to describe a phase transition in films subjected to periodic boundary conditions and influenced by an external and constant magnetic field. Criticality is studied and the relations between the critical temperature, the film thickness, the magnetic field strength and the chemical potential are investigated. Since the model describes a second-order phase transition a comparison with the Ginzburg-Landau theory is made. (orig.)
Study of deformation of droplet in external force field by using liquid-gas model of lattice-gas
International Nuclear Information System (INIS)
Ebihara, Ken-ichi; Watanabe, Tadashi
2000-10-01
The deformation of the droplet by the external force which is assumed to be gravity is studied by using the liquid-gas model of lattice-gas. Two types of liquid-gas models, one is the minimal model and the other is the maximal model, which are distinguished from each other by the added long-range interactions are used for the simulation of the droplet deformation. The difference of the droplet deformation between the maximal model and the minimal model was observed. While the droplet of the minimal model elongates in the direction of the external force, the droplet of the maximal model elongates in the perpendicular direction to the external force. Therefore the droplet deformation in the external force field of the maximal model is more similar to the droplet deformation which is observed in experiments than that of the minimal model. (author)
International Nuclear Information System (INIS)
Hramov, Alexander; Koronovskii, Alexey; Morozov, Mikhail; Mushtakov, Alexander
2008-01-01
In this Letter we research the space charge limiting current value at which the oscillating virtual cathode is formed in the relativistic electron beam as a function of the external magnetic field guiding the beam electrons. It is shown that the space charge limiting (critical) current decreases with growth of the external magnetic field, and that there is an optimal induction value of the magnetic field at which the critical current for the onset of virtual cathode oscillations in the electron beam is minimum. For the strong external magnetic field the space charge limiting current corresponds to the analytical relation derived under the assumption that the motion of the electron beam is one-dimensional [D.J. Sullivan, J.E. Walsh, E. Coutsias, in: V.L. Granatstein, I. Alexeff (Eds.), Virtual Cathode Oscillator (Vircator) Theory, in: High Power Microwave Sources, vol. 13, Artech House Microwave Library, 1987, Chapter 13]. Such behavior is explained by the characteristic features of the dynamics of electron space charge in the longitudinal and radial directions in the drift space at the different external magnetic fields
Shaymatov, Sanjar; Ahmedov, Bobomurat; Stuchlík, Zdeněk; Abdujabbarov, Ahmadjon
We investigate particle motion and collisions in the vicinity of rotating black holes immersed in combined cosmological quintessential scalar field and external magnetic field. The quintessential dark-energy field governing the spacetime structure is characterized by the quintessential state parameter ωq ∈ (‑1; ‑1/3) characterizing its equation of state, and the quintessential field-intensity parameter c determining the static radius where the black hole attraction is just balanced by the quintessential repulsion. The magnetic field is assumed to be test field that is uniform close to the static radius, where the spacetime is nearly flat, being characterized by strength B there. Deformations of the test magnetic field in vicinity of the black hole, caused by the Ricci non-flat spacetime structure are determined. General expression of the center-of-mass energy of the colliding charged or uncharged particles near the black hole is given and discussed in several special cases. In the case of nonrotating black holes, we discuss collisions of two particles freely falling from vicinity of the static radius, or one such a particle colliding with charged particle revolving at the innermost stable circular orbit. In the case of rotating black holes, we discuss briefly particles falling in the equatorial plane and colliding in close vicinity of the black hole horizon, concentrating attention to the interplay of the effects of the quintessential field and the external magnetic field. We demonstrate that the ultra-high center-of-mass energy can be obtained for black holes placed in an external magnetic field for an infinitesimally small quintessential field-intensity parameter c; the center-of-mass energy decreases if the quintessential field-intensity parameter c increases.
Simulation mechanisms of low energy nuclear reaction using super flow energy external fields
International Nuclear Information System (INIS)
Gareev, F.A.; Zhidkova, I.E.; ); Ratis, Yu.I.
2005-01-01
Full text: The review of possible stimulation mechanisms of the LENR (low energy nuclear reactions) is represented. We have concluded that transamination of nuclei at low energies and excess heat are possible in the framework of the modern physical theory - the universal resonance synchronization principle and based on its different enhancement mechanisms of reaction rates are responsible for these processes. The excitation nd ionization of atom may play role as trigger for LERN. Investigation of this phenomenon requires knowledge of different branches if science: nuclear and atomic physics, chemistry and electrochemistry, condensed matter and solid state physics. The results of this research field can provide a new source of energy, substances and technologies. The puzzle of poor re-productivity of experimental data in due ti the fact LENR occurs in open systems and it is extremely sensitive to parameters of external fields and systems. Classical re-productivity principle should be reconsidered for LENR experiments. Poor re-productivity and unexpected results do not means that the experiment is wrong. Our main conclusion: LENR may be understand in terms of the modern theory without any violation of the basic physics. 2) Weak and electromagnetic interactions may show the strong influence of the surrounding conditions on the nuclear processes. 3) Universal resonance synchronization principle is a key issue to make a bridge between various scales of interactions and it is responsible for self-organization of hierarchical systems independent of substances, fields and interactions. We bring some arguments in favor of the mechanism - order based on order - declared by Schroedinger in fundamental problem of contemporary science. 4) The universal resonance synchronization principle became a fruitful interdisciplinary science of general laws of self-organized processes in different branches of physics because it is consequence of the energy conservation law and resonance
International Nuclear Information System (INIS)
Luo Yu-Pin; Tien Li-Gan; Tsai Chuen-Horng; Lee Ming-Hsien; Li Feng-Yin
2011-01-01
Ab initio calculations demonstrated that the energy gap modulation of a chiral carbon nanotube with mono-vacancy defect can be achieved by applying a transverse electric field. The bandstructure of this defective carbon nanotube varying due to the external electric field is distinctly different from those of the perfect nanotube and defective zigzag nanotube. This variation in bandstructure strongly depends on not only the chirality of the nanotube and also the applied direction of the transverse electric field. A mechanism is proposed to explain the response of the local energy gap between the valence band maximum state and the local gap state under external electric field. Several potential applications of these phenomena are discussed. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Energy Technology Data Exchange (ETDEWEB)
Ding, Baofu, E-mail: b.ding@ecu.edu.au; Alameh, Kamal, E-mail: k.alameh@ecu.edu.au [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027 (Australia)
2014-07-07
The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.
International Nuclear Information System (INIS)
Ding, Baofu; Alameh, Kamal
2014-01-01
The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.
Energy Technology Data Exchange (ETDEWEB)
Derakhshani, Kamran, E-mail: kderakhshani@iasbs.ac.ir [Institute for Advanced Studies in Basic Sciences, P. O. Box 45195-1159 Zanjan (Iran, Islamic Republic of)
2014-03-01
In this paper, we investigate the external field effect in the context of the MOdified Newtonian Dynamics (MOND) on the surface brightness and velocity dispersion profiles of globular clusters (GCs). Using N-MODY, which is an N-body simulation code with a MOND potential solver, we show that the general effect of the external field for diffuse clusters, which obey MOND in most of their parts, is that it pushes the dynamics toward the Newtonian regime. On the other hand, for more compact clusters, which are essentially Newtonian in their inner parts, the external field is effective mainly in the outer parts of compact clusters. As a case study, we then choose the remote Galactic GC NGC 2419. By varying the cluster mass, half-light radius, and mass-to-light ratio, we aim to find a model that will reproduce the observational data most effectively, using N-MODY. We find that even if we take the Galactic external field into account, a Newtonian Plummer sphere represents the observational data better than MOND to an order of magnitude in terms of the total χ{sup 2} of surface brightness and velocity dispersion.
International Nuclear Information System (INIS)
Derakhshani, Kamran
2014-01-01
In this paper, we investigate the external field effect in the context of the MOdified Newtonian Dynamics (MOND) on the surface brightness and velocity dispersion profiles of globular clusters (GCs). Using N-MODY, which is an N-body simulation code with a MOND potential solver, we show that the general effect of the external field for diffuse clusters, which obey MOND in most of their parts, is that it pushes the dynamics toward the Newtonian regime. On the other hand, for more compact clusters, which are essentially Newtonian in their inner parts, the external field is effective mainly in the outer parts of compact clusters. As a case study, we then choose the remote Galactic GC NGC 2419. By varying the cluster mass, half-light radius, and mass-to-light ratio, we aim to find a model that will reproduce the observational data most effectively, using N-MODY. We find that even if we take the Galactic external field into account, a Newtonian Plummer sphere represents the observational data better than MOND to an order of magnitude in terms of the total χ 2 of surface brightness and velocity dispersion.
Wei, Liew Tze; Sazilah, Salam
2012-01-01
This study investigated the effects of visual cues in multiple external representations (MER) environment on the learning performance of novices' program comprehension. Program codes and flowchart diagrams were used as dual representations in multimedia environment to deliver lessons on C-Programming. 17 field independent participants and 16 field…
In situ observation of magnetic vortex manipulation by external fields in amorphous CeFeB ribbon
International Nuclear Information System (INIS)
Zuo, Shulan; Zhang, Ming; Li, Rui; Zhang, Ying; Peng, Licong; Xiong, Jiefu; Liu, Dan; Zhao, Tongyun; Hu, Fengxia; Shen, Baogen; Sun, Jirong
2017-01-01
In this study, we show the real-space observation of the magnetic domain configuration in amorphous Ce 14 Fe 80 B 6 ribbon using Lorentz transmission electron microscopy. Cross-tie domain walls composed of magnetic vortices (Vs) and antivortices (AVs) are observed. The evolution of Vs/AVs manipulated by temperature, in-plane magnetic field, and electrical current is clearly demonstrated. Magnetic V nucleation and annihilation in pair are observed because of the stimulus of external fields.
International Nuclear Information System (INIS)
Girka, V O; Puzyrkov, S Yu; Shpagina, V O; Shpagina, L O
2012-01-01
The application of an external alternating electric field in the range of ion cyclotron frequencies is a well-known method for the excitation of surface electromagnetic waves. The present paper is devoted to the development of a kinetic theory of parametric excitation of these eigenwaves propagating across an external steady magnetic field along the plasma boundary at the second harmonic of the ion cyclotron frequency. Unlike previous papers on this subject, parametric excitation of surface ion cyclotron X-modes is studied here under the condition of non-monochromaticity of an external alternating electric field. Non-monochromaticity of the external alternating electric field is modeled by the superposition of two uniform and monochromatic electric fields with different amplitudes and frequencies. The nonlinear boundary condition is formulated for a tangential magnetic field of the studied surface waves. An infinite set of equations for the harmonics of a tangential electric field is solved using the approximation of the wave packet consisting of the main harmonic and two nearest satellite harmonics. Two different regimes of instability have been considered. If one of the applied generators has an operation frequency that is close to the ion cyclotron frequency, then changing the amplitude of the second generator allows one to enhance the growth rate of the parametric instability or to diminish it. But if the operation frequencies of the both generators are not close to the ion cyclotron frequency, then changing the amplitudes of their fields allows one to decrease the growth rate of the instability and even to suppress its development. The problem is studied both analytically and numerically.
International Nuclear Information System (INIS)
Erdinc, Ahmet; Canko, Osman; Keskin, Mustafa
2006-01-01
We have studied the antiferromagnetic Blume-Emery-Griffiths model with the repulsive biquadratic coupling in an external magnetic field using the lowest approximation of the cluster variation method which is identical to the mean-field approximation. First, we have investigated the thermal variations of the sublattice magnetizations and obtained four different main topological types. Then, we have calculated the phase diagrams and five main different phase diagram topologies are found. Finally, the discussion and comparison of the phase diagrams are made
Energy Technology Data Exchange (ETDEWEB)
Erdinc, Ahmet [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)]. E-mail: keskin@erciyes.edu.tr
2006-06-15
We have studied the antiferromagnetic Blume-Emery-Griffiths model with the repulsive biquadratic coupling in an external magnetic field using the lowest approximation of the cluster variation method which is identical to the mean-field approximation. First, we have investigated the thermal variations of the sublattice magnetizations and obtained four different main topological types. Then, we have calculated the phase diagrams and five main different phase diagram topologies are found. Finally, the discussion and comparison of the phase diagrams are made.
Asner, A
1985-01-01
Compensation of the magnetization current induced sextupole error at LHC injection field by short lumped permanent sextupole magnets, incorporated into the end configuration of superconducting dipoles
Sheared electric field-induced suppression of edge turbulence using externally driven R.F. waves
International Nuclear Information System (INIS)
Craddock, G.G.; Diamond, P.H.
1991-01-01
Here the authors propose a novel method for active control and suppression of edge turbulence by sheared ExB flows driven by externally launched RF waves. The theory developed addresses the problem of open-quotes flow driveclose quotes, which is somewhat analogous to the problem of plasma current drive. As originally demonstrated for the case of spontaneously driven flows, a net difference in the gradient of the fluid and magnetic Reynolds' stresses produced by radially propagating waves can drive the plasma flow. For the prototypical case of the Alfven wave flow drive considered here, ρ 0 r v θ > - r B θ > is proportional to k perpendicular 2 ρ s 2 in the case of the kinetic Alfven wave, and [(ηk perpendicular 2 -vk perpendicular 2 )/ω] 2 in the case of resistive MHD. Both results reflect the dependence of flow drive on the net stress imbalance. The shear layer width is determined by the waves evanescence length (determined by dissipation) that sets the stress gradient scale length, while the direction of the flow is determined by the poloidal orientation of the launched waves. In particular, it should be noted that both positive and negative E r may be driven, so that enhanced confinement need not be accompanied by impurity accumulation, as commonly encountered in spontaneous H-modes. The efficiency is determined by the criterion that the radial electric field shear be large enough to suppress turbulence. For typical TEXT parameters, and unity efficiency, 300 kW of absorbed power is needed to suppress turbulence over 3 cm radially. For DIII-D, 300 kW over 4 cm is needed. Also, direct transport losses induced by RF have been shown to be small. Extensions of the theory to ICRF are underway and are discussed. They also discuss the analogous problem of current drive using kinetic Alfven waves. 2 refs
Luo, Dao-sheng; Mi, Qi-wu; Meng, Xiang-jun; Gao, Yong; Dai, Yu-ping; Deng, Chun-hua
2012-08-18
To study the synergetic killing effects of external magnetic fields combined with the photodynamic action of porphyrin-dextran iron oxide magnetic nanoparticles (PDMN) on human bladder cancer cells in vitro. The PDMN were produced by using the chemical co-precipitation and redox process and the physicochemical properties were characterized. Methyl thiazolyl tetrazolium (MTT) and flow cytometry were used to determine the effects of photodynamic therapy of PDMN combined with external pulsed electromagnetic fields (5 mT) on killing human bladder cancer BIU-87 cells respectively. The diameters of PDMN were 10-15 nm and the saturation magnetization was 0.20 emu/g. Effective diameter of PDMN was 94.8 nm. PDMN could remarkably inhibit the proliferation and induce the obvious apoptosis of BIU-87 cells, and the rates of growth inhibition and apoptosis were (17.61±2.73)% and (24.53±5.74)% respectively. Moreover, external pulsed electromagnetic fields (5 mT) could also suppress the proliferation and induce apoptosis of BIU-87 cells. Furthermore, the photodynamic action of PDMN combined with external magnetic fields significantly inhibited the proliferation and promote apoptosis of BIU-87 cells, and the rates of growth inhibition and apoptosis was (28.11±4.25)% and (24.53±5.74)%, respectively, which were significantly higher than those of other groups (Peffectively inhibit proliferation and induce apoptosis of BIU-87 cells. Moreover, these effects on BIU-87 cells could be strengthened by the combination with external magnetic fields.
Energy Technology Data Exchange (ETDEWEB)
Konobeeva, N.N., E-mail: yana_nn@inbox.ru [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Belonenko, M.B. [Volgograd Institute of Business, Uzhno-ukrainskaya str., Volgograd 400048 (Russian Federation)
2014-04-01
The paper addresses the propagation of ultra-short optical pulses in chiral carbon nanotubes in the presence of external alternating electric field. Following the assumption that the considered optical pulses are represented in the form of discrete solitons, we analyze the wave equation for the electromagnetic field and consider the dynamics of pulses in external field, their initial amplitudes and frequencies.
International Nuclear Information System (INIS)
Gedik, Engin; Recebli, Ziyaddin; Kurt, Hueseyin; Kecebas, Ali
2012-01-01
The unsteady viscous incompressible and electrically conducting of two-phase fluid flow in circular pipes with external magnetic and electrical field is considered in this present study. Effects of both uniform transverse external magnetic and electrical fields applied perpendicular to the fluid and each other on the two-phase (solid/liquid) unsteady flow is investigated numerically. While iron powders are being used as the first phase of two-phase fluid, pure water was used as the second phase. The system of the derived governing equations, which are based on the Navier-Stokes equations including Maxwell equations, are solved numerically by using Pdex4 function on the Matlab for both phases. The originality of this study is that, in addition to magnetic field, the effect of electrical field on two-phase unsteady fluids is being examined. The magnetic field which is applied on flow decreases the velocity of both phases, whereas the electrical field applied along with magnetic field acted to increase and decrease the velocity values depending on the direction of electrical field. Electrical field alone did not display any impact on two-phase flow. On the other hand, analytical and numerical results are compared and favorable agreements have been obtained. (authors)
Density scaling on n = 1 error field penetration in ohmically heated discharges in EAST
Wang, Hui-Hui; Sun, You-Wen; Shi, Tong-Hui; Zang, Qing; Liu, Yue-Qiang; Yang, Xu; Gu, Shuai; He, Kai-Yang; Gu, Xiang; Qian, Jin-Ping; Shen, Biao; Luo, Zheng-Ping; Chu, Nan; Jia, Man-Ni; Sheng, Zhi-Cai; Liu, Hai-Qing; Gong, Xian-Zu; Wan, Bao-Nian; Contributors, EAST
2018-05-01
Density scaling of error field penetration in EAST is investigated with different n = 1 magnetic perturbation coil configurations in ohmically heated discharges. The density scalings of error field penetration thresholds under two magnetic perturbation spectra are br\\propto n_e0.5 and br\\propto n_e0.6 , where b r is the error field and n e is the line averaged electron density. One difficulty in understanding the density scaling is that key parameters other than density in determining the field penetration process may also be changed when the plasma density changes. Therefore, they should be determined from experiments. The estimated theoretical analysis (br\\propto n_e0.54 in lower density region and br\\propto n_e0.40 in higher density region), using the density dependence of viscosity diffusion time, electron temperature and mode frequency measured from the experiments, is consistent with the observed scaling. One of the key points to reproduce the observed scaling in EAST is that the viscosity diffusion time estimated from energy confinement time is almost constant. It means that the plasma confinement lies in saturation ohmic confinement regime rather than the linear Neo-Alcator regime causing weak density dependence in the previous theoretical studies.
DEFF Research Database (Denmark)
Gaynor, J. E.; Kristensen, Leif
1986-01-01
Observatory tower. The approximate magnitude of the error due to spatial and temporal pulse volume separation is presented as a function of mean wind angle relative to the sodar configuration and for several antenna pulsing orders. Sodar-derived standard deviations of the lateral wind component, before...
Influence of an external magnetic field on damage by self-ion irradiation in Fe90Cr10 alloy
Directory of Open Access Journals (Sweden)
Fernando José Sánchez
2016-12-01
Full Text Available The effect of an external magnetic field (B=0.5 T on Fe90Cr10 specimens during Fe ion irradiation, has been investigated by means of Conversion Electron Mössbauer Spectroscopy (CEMS. The analysis has revealed significant differences in the average hyperfine magnetic field (=0.3 T between non-irradiated and irradiated samples as well as between irradiations made with B (w/ B and without B (w/o B. It is considered that these variations can be due to changes in the local environment around the probe nuclei (57Fe; where vacancies and Cr distribution play a role. The results indicate that the Cr distribution in the neighbourhood of the iron atoms could be changed by the application of an external field. This would imply that an external magnetic field may be an important parameter to take into account in predictive models for Cr behaviour in Fe–Cr alloys, and especially in fusion conditions where intense magnetic fields are required for plasma confinement.
Berland, Kristian; Einstein, T. L.; Hyldgaard, Per
2012-02-01
To manipulate the Cu(111) partially-filled Shockley surface state, we study its response to an external fieldootnotetextKB, TLE, PH; arXiv 1109:6706 E and physisorbed PAHs and quinone molecules. We use density-functional theory calculations with periodic-boundary conditions. The van der Waals density functional version vdW-DF2 accounts for the molecular adsorption. The issue that the Kohn-Sham wave functions couple to both sides of the Cu slab is handled with a decoupling scheme based on a rotation in Hilbert space. A convergence study reveals that to obtain a proper Shockley surface state, 6 Cu layers is sufficient, while 15 is optimal. We use 6 layers for the response to the molecules and 15 to external field. We find that the surface state displays isotropic dispersion (up to order k^6), free-electron like until the Fermi wave vector but with a significant quartic component beyond. The shift in band minimum and effective mass depend linearly on E, with a smaller fractional change in the latter. Charge transfer occurs beyond the outermost copper atoms, and most of the screening is due to bulk electrons. We find that the molecular physisorption increases the band minimum, with the effect the of a quinone being much stronger than the corresponding PAH.
International Nuclear Information System (INIS)
Knuefer; Lindauer
1980-01-01
Besides that at spectacular events a combination of component failure and human error is often found. Especially the Rasmussen-Report and the German Risk Assessment Study show for pressurised water reactors that human error must not be underestimated. Although operator errors as a form of human error can never be eliminated entirely, they can be minimized and their effects kept within acceptable limits if a thorough training of personnel is combined with an adequate design of the plant against accidents. Contrary to the investigation of engineering errors, the investigation of human errors has so far been carried out with relatively small budgets. Intensified investigations in this field appear to be a worthwhile effort. (orig.)
International Nuclear Information System (INIS)
Vaskes-Luna, Kh.G.; Zekhe, A.; Nhukhil'o-Garsiya, M.P.; Starostenko, O.
2000-01-01
The effect of external magnetic field on obtaining thin CdS films on glass sub layers through the method of chemical deposition from the cadmium chloride aqueous solution is studied. The intensity and direction of the magnetic field during deposition obviously affect the number of physical properties of polycrystalline films: thickness, grain size and optical quality. The films characteristics are studied through an atomic-power microscope, light absorption spectroscopy and conductometry in darkness. The results obtained are interpreted on the basis of notions on the cadmium and sulfur specific interaction in the chemical bath with a magnetic field [ru
Nasehi, R.; Norouzi, F.
2016-08-01
The theoretical investigation of controlling the optical bistability (OB) and optical multistability (OM) in a dielectric medium doped with nanodiamond nitrogen vacancy centres under optical excitation are reported. The shape of the OB curve from dielectric slab can be tuned by changing the external magnetic field and polarization of the control beam. The effect of the intensity of the control laser field and the frequency detuning of probe laser field on the OB and OM behaviour are also discussed in this paper. The results obtained can be used for realizing an all-optical bistable switching or development of nanoelectronic devices.
Directory of Open Access Journals (Sweden)
TIAN Jialei
2015-11-01
Full Text Available By using the ground as the boundary, Molodensky problem usually gets the solution in form of series. Higher order terms reflect the correction between a smooth surface and the ground boundary. Application difficulties arise from not only computational complexity and stability maintenance, but also data-intensiveness. Therefore, in this paper, starting from the application of external gravity disturbance, Green formula is used on digital terrain surface. In the case of ignoring the influence of horizontal component of the integral, the expression formula of external disturbance potential determined by boundary value consisted of ground gravity anomalies and height anomaly difference are obtained, whose kernel function is reciprocal of distance and Poisson core respectively. With this method, there is no need of continuation of ground data. And kernel function is concise, and suitable for the stochastic computation of external disturbing gravity field.
Chegel, Raad; Behzad, Somayeh
2014-02-01
We investigated the electronic properties of silicon nanotubes (SiNTs) under external transverse electric fields and axial magnetic fields using the tight-binding approximation. It was found that, after switching on the electric and magnetic fields, band modifications such as distortion of degeneracy, change in energy dispersion and subband spacing, and bandgap size reduction occur. The bandgap of silicon gear-like nanotubes (Si g-NTs) decreases linearly with increasing electric field strength, but the bandgap for silicon hexagonal nanotubes (Si h-NTs) first increases and then decreases (metallic) or first remains constant and then decreases (semiconducting). Our results show that the bandgap of Si h-NTs is very sensitive to both electric and magnetic fields, unlike Si g-NTs, which are more sensitive to electric than magnetic fields.
Bao, Guzhi; Wickenbrock, Arne; Rochester, Simon; Zhang, Weiping; Budker, Dmitry
2018-01-19
The nonlinear Zeeman effect can induce splitting and asymmetries of magnetic-resonance lines in the geophysical magnetic-field range. This is a major source of "heading error" for scalar atomic magnetometers. We demonstrate a method to suppress the nonlinear Zeeman effect and heading error based on spin locking. In an all-optical synchronously pumped magnetometer with separate pump and probe beams, we apply a radio-frequency field which is in phase with the precessing magnetization. This results in the collapse of the multicomponent asymmetric magnetic-resonance line with ∼100 Hz width in the Earth-field range into a single peak with a width of 22 Hz, whose position is largely independent of the orientation of the sensor within a range of orientation angles. The technique is expected to be broadly applicable in practical magnetometry, potentially boosting the sensitivity and accuracy of Earth-surveying magnetometers by increasing the magnetic-resonance amplitude, decreasing its width, and removing the important and limiting heading-error systematic.
Bao, Guzhi; Wickenbrock, Arne; Rochester, Simon; Zhang, Weiping; Budker, Dmitry
2018-01-01
The nonlinear Zeeman effect can induce splitting and asymmetries of magnetic-resonance lines in the geophysical magnetic-field range. This is a major source of "heading error" for scalar atomic magnetometers. We demonstrate a method to suppress the nonlinear Zeeman effect and heading error based on spin locking. In an all-optical synchronously pumped magnetometer with separate pump and probe beams, we apply a radio-frequency field which is in phase with the precessing magnetization. This results in the collapse of the multicomponent asymmetric magnetic-resonance line with ˜100 Hz width in the Earth-field range into a single peak with a width of 22 Hz, whose position is largely independent of the orientation of the sensor within a range of orientation angles. The technique is expected to be broadly applicable in practical magnetometry, potentially boosting the sensitivity and accuracy of Earth-surveying magnetometers by increasing the magnetic-resonance amplitude, decreasing its width, and removing the important and limiting heading-error systematic.
Moessbauer study of LaFeAsO and F-doped superconductors in external magnetic fields
International Nuclear Information System (INIS)
Kitao, S; Kobayashi, Y; Higashitaniguchi, S; Kurokuzu, M; Saito, M; Seto, M; Mitsui, T; Kamihara, Y; Hirano, M; Hosono, H
2010-01-01
The iron-based F-doped superconductors LaFeAsO 1-x F x with a transition temperature of 24 K (for x = 0.07) and 26 K (x = 0.11) and its parent material LaFeAsO were studied using 57 Fe Moessbauer spectroscopy. Further investigation was carried out by applying external magnetic fields. F-doped superconductors showed a singlet pattern with no magnetic splitting throughout the temperature range from 4.2 to 298 K. On the other hand, magnetically-split spectra were observed in the parent LaFeAsO below the Neel temperature of about 140 K. The internal magnetic field reached 5.3 T at 4.2 K. The external magnetic fields up to 14 T were applied to the singlet phases, F-doped superconductors and the parent LaFeAsO above the Neel temperature. The induced magnetically-split spectra showed the internal magnetic fields with the comparable value to the applied fields. This fact confirmed that these singlet phases have the paramagnetic feature. The magnetic fields were also applied to the magnetically-ordered phase of LaFeAsO below the Neel temperature. The evolution of the spectra depending on the external magnetic fields was clearly explained by a model with two sublattice spins of the powdered antiferromagnet. This fact confirmed the magnetically-ordered phase is an antiferromagnet. The spin-flop field was also estimated by the model as about 26 T.
Fan, Kaimin; Tang, Jing; Wu, Shiyun; Yang, Chengfu; Hao, Jiabo
2016-12-21
The adsorption and diffusion behaviors of lithium (Li) in a graphene/blue-phosphorus (G/BP) heterostructure have been investigated using a first principles method based on density functional theory (DFT). The effect of an external electric field on the adsorption and diffusion behaviors has also been investigated. The results show that the adsorption energy of Li on the graphene side of the G/BP heterostructure is higher than that on monolayer graphene, and Li adsorption on the BP side of the G/BP/Li system is slightly stronger than that on monolayer BP (BP/Li). The adsorption energy of Li reaches 2.47 eV, however, the energy barriers of Li diffusion decrease in the interlayer of the G/BP heterostructure. The results mentioned above suggest that the rate performance of the G/BP heterostructure is better than that of monolayer graphene. Furthermore, the adsorption energies of Li atoms in the three different most stable sites, i.e., H G , T P and H 1 sites, increase by about 0.49 eV, 0.26 eV, and 0.13 eV, respectively, as the electric field intensity reaches 0.6 V Å -1 . The diffusion energy barrier is significantly decreased by an external electric field. It is demonstrated that the external electric field can not only enhance the adsorption but can also modulate the diffusion barriers of Li atoms in the G/BP heterostructure.
Pitel, J; Lehtonen, J; Kovács, P
2002-01-01
We have developed a mathematical model, which enables us to predict the voltage-current V(I) characteristics of a solenoidal high-temperature superconductor (HTS) magnet subjected to an external magnetic field parallel to the magnet axis. The model takes into account the anisotropy in the critical current-magnetic field (I sub c (B)) characteristic and the n-value of Bi(2223)Ag multifilamentary tape at 20 K. From the power law between the electric field and the ratio of the operating and critical currents, the voltage on the magnet terminals is calculated by integrating the contributions of individual turns. The critical current of each turn, at given values of operating current and external magnetic field, is obtained by simple linear interpolation between the two suitable points of the I sub c (B) characteristic, which corresponds to the angle alpha between the vector of the resulting magnetic flux density and the broad tape face. In fact, the model is valid for any value and orientation of external magneti...
International Nuclear Information System (INIS)
Li Min; Li An-Yuan; Yuan Shuai; Zeng He-Ping; He Bo-Qu
2016-01-01
Terahertz generation driven by dual-color filaments in air is demonstrated to be remarkably enhanced by applying an external electric field to the filaments. As terahertz generation is sensitive to the dual-color phase difference, a preformed plasma is verified efficiently in modulating terahertz radiation from linear to elliptical polarization. In the presence of preformed plasma, a dual-color filament generates terahertz pulses of elliptical polarization and the corresponding ellipse rotates regularly with the change of the preformed plasma density. The observed terahertz modulation with the external electric field and the preformed plasma provides a simple way to estimate the plasma density and evaluate the photocurrent dynamics of the dual-color filaments. It provides further experimental evidence of the photo-current model in governing the dual-color filament driven terahertz generation processes. (paper)