An analytic map for space charge in a nonlinear lattice
Energy Technology Data Exchange (ETDEWEB)
Benedetti, C. [Dipartimento di Fisica Universita di Bologna and INFN, Via Irnerio 46, 40126 Bologna (Italy)]. E-mail: benedetti@bo.infn.it; Turchetti, G. [Dipartimento di Fisica Universita di Bologna and INFN, Via Irnerio 46, 40126 Bologna (Italy)
2005-06-13
We propose a simple analytical model for an intense beam in a lattice with localized nonlinearities. In the thin lens limit a single nonlinearity leads to a Henon like map. When the space charge is present and the core radius is small with respect to the dynamic aperture, the use of a frozen core distribution like KV is justified. In this case we define an analytic map M by composing the phase advance due to space charge, computed at the first perturbation order, with the kick due to the nonlinear force. The corresponding dynamics is almost indistinguishable from the dynamics of the 'exact' map, which requires an accurate symplectic integration, if the tune depression is weak enough. The same accuracy is preserved for parametric modulations of the perveance or the beam core radius. The extension to any other distribution is straightforward.
On Landau damping of dipole modes by non-linear space charge and octupoles
Möhl, D
1995-01-01
The joint effect of space-charge non-linearities and octupole lenses is important for Landau damping of coherent instabilities. The octupole strength required for stabilisation can depend strongly on the sign of the excitation current of the lenses. This note tries to extend results, previously obtained for coasting beams and rigid bunches, to more general head--tail modes.
Suppression of space charge induced beam halo in nonlinear focusing channel
Batygin, Yuri K.; Scheinker, Alexander; Kurennoy, Sergey; Li, Chao
2016-04-01
An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The problem is connected with irreversible distortion of phase space volume of the beam in conventional focusing structures due to filamentation in phase space. Emittance growth is accompanied by halo formation in real space, which results in inevitable particle losses. A new approach for solving a self-consistent problem for a matched non-uniform beam in two-dimensional geometry is discussed. The resulting solution is applied to the problem of beam transport, while avoiding emittance growth and halo formation by the use of nonlinear focusing field. Conservation of a beam distribution function is demonstrated analytically and by particle-in-cell simulation for a beam with a realistic beam distribution.
Suppression of Space Charge Induced Beam Halo in Nonlinear Focusing Channel
Batygin, Yuri K; Kurennoy, Sergey; Li, Chao
2016-01-01
An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The problem is connected with irreversible distortion of phase space volume of the beam in conventional focusing structures due to filamentation in phase space. Emittance growth is accompanied by halo formation in real space, which results in inevitable particle losses. A new approach for solving a self-consistent problem for a matched non-uniform beam in two-dimensional geometry is discussed. The resulting solution is applied to the problem of beam transport, while avoiding emittance growth and halo formation by the use of nonlinear focusing field. Conservation of a beam distribution function is demonstrated analytically and by particle-in-cell simulation for a beam with a realistic beam distribution.
Frequency map analysis of resonances in a nonlinear lattice with space charge
Energy Technology Data Exchange (ETDEWEB)
Turchetti, G. E-mail: turchetti@bo.infn.it; Bazzani, A.; Bergamini, F.; Rambaldi, S.; Hofmann, I.; Bongini, L.; Franchetti, G
2001-05-21
In storage rings for heavy ion fusion beam losses must be minimized. During bunch compression high space charge is reached and the reciprocal effects between the collective modes of the beam and the single particle lattice nonlinearities must be considered to understand the problem of resonance crossing and halo formation. We show that the frequency map analysis of particle in core models gives an adequate description of the resonance network and of the chaotic regions where the halo particles can diffuse.
Institute of Scientific and Technical Information of China (English)
GAO Jie
2009-01-01
In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC Ⅱ. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.
Zhang, Zhen; Yan, Lixin; Du, Yingchao; Zhou, Zheng; Su, Xiaolu; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Shi, Jiaru; Chen, Huaibi; Huang, Wenhui; Gai, Wei; Tang, Chuanxiang
2016-05-01
High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally with the goal of generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic electron beam and controlling the charge density over the beam propagation, density spikes of several-hundred-ampere peak current in the temporal profile, which are several times higher than the initial amplitudes, have been observed for the first time. We also demonstrate that the periodic spacing of the bunch train can be varied continuously either by tuning launching phase of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. Narrow-band coherent THz radiation from the bunch train was also measured with μ J -level energies and tunable central frequency of the spectrum in the range of ˜0.5 to 1.6 THz. Our results pave the way towards generating mJ-level narrow-band coherent THz radiation and driving high-gradient wakefield-based acceleration.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zhen; Yan, Lixin; Du, Yingchao; Zhou, Zheng; Su, Xiaolu; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Shi, Jiaru; Chen, Huaibi; Huang, Wenhui; Gai, Wei; Tang, Chuanxiang
2016-05-05
High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally with the goal of generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic electron beam and controlling the charge density over the beam propagation, density spikes of several-hundred-ampere peak current in the temporal profile, which are several times higher than the initial amplitudes, have been observed for the first time. We also demonstrate that the periodic spacing of the bunch train can be varied continuously either by tuning launching phase of a radiofrequency gun or by tuning the compression of a downstream magnetic chicane. Narrow-band coherent THz radiation from the bunch train was also measured with μJ-level energies and tunable central frequency of the spectrum in the range of ~0.5 to 1.6 THz. Our results pave the way towards generating mJ-level narrow-band coherent THz radiation and driving high-gradient wakefield-based acceleration.
BRST charge for nonlinear algebras
Buchbinder, I L
2007-01-01
We study the construction of the classical nilpotent canonical BRST charge for the nonlinear gauge algebras where a commutator (in terms of Poisson brackets) of the constraints is a finite order polynomial of the constraints.
Chauvin, N
2013-01-01
First, this chapter introduces the expressions for the electric and magnetic space-charge internal fields and forces induced by high-intensity beams. Then, the root-mean-square equation with space charge is derived and discussed. In the third section, the one-dimensional Child-Langmuir law, which gives the maximum current density that can be extracted from an ion source, is exposed. Space-charge compensation can occur in the low-energy beam transport lines (located after the ion source). This phenomenon, which counteracts the spacecharge defocusing effect, is explained and its main parameters are presented. The fifth section presents an overview of the principal methods to perform beam dynamics numerical simulations. An example of a particles-in-cells code, SolMaxP, which takes into account space-charge compensation, is given. Finally, beam dynamics simulation results obtained with this code in the case of the IFMIF injector are presented.
Miskovic, Olivera
2010-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/Conformal Field Theory (AdS/CFT) correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by a nonlinear electrodynamics (NED) are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary NED Lagrangian, in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Fall-off conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass...
Mišković, Olivera; Olea, Rodrigo
2011-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.
The Nonlinear Field Space Theory
Mielczarek, Jakub; Trześniewski, Tomasz
2016-08-01
In recent years the idea that not only the configuration space of particles, i.e. spacetime, but also the corresponding momentum space may have nontrivial geometry has attracted significant attention, especially in the context of quantum gravity. The aim of this letter is to extend this concept to the domain of field theories, by introducing field spaces (i.e. phase spaces of field values) that are not affine spaces. After discussing the motivation and general aspects of our approach we present a detailed analysis of the prototype (quantum) Nonlinear Field Space Theory of a scalar field on the Minkowski background. We show that the nonlinear structure of a field space leads to numerous interesting predictions, including: non-locality, generalization of the uncertainty relations, algebra deformations, constraining of the maximal occupation number, shifting of the vacuum energy and renormalization of the charge and speed of propagation of field excitations. Furthermore, a compact field space is a natural way to implement the "Principle of finiteness" of physical theories, which once motivated the Born-Infeld theory. Thus the presented framework has a variety of potential applications in the theories of fundamental interactions (e.g. quantum gravity), as well as in condensed matter physics (e.g. continuous spin chains), and can shed new light on the issue of divergences in quantum field theories.
The Nonlinear Field Space Theory
Energy Technology Data Exchange (ETDEWEB)
Mielczarek, Jakub, E-mail: jakub.mielczarek@uj.edu.pl [Institute of Physics, Jagiellonian University, ul. Łojasiewicza 11, 30-348 Kraków (Poland); Trześniewski, Tomasz, E-mail: tbwbt@ift.uni.wroc.pl [Institute of Physics, Jagiellonian University, ul. Łojasiewicza 11, 30-348 Kraków (Poland); Institute for Theoretical Physics, University of Wrocław, pl. Borna 9, 50-204 Wrocław (Poland)
2016-08-10
In recent years the idea that not only the configuration space of particles, i.e. spacetime, but also the corresponding momentum space may have nontrivial geometry has attracted significant attention, especially in the context of quantum gravity. The aim of this letter is to extend this concept to the domain of field theories, by introducing field spaces (i.e. phase spaces of field values) that are not affine spaces. After discussing the motivation and general aspects of our approach we present a detailed analysis of the prototype (quantum) Nonlinear Field Space Theory of a scalar field on the Minkowski background. We show that the nonlinear structure of a field space leads to numerous interesting predictions, including: non-locality, generalization of the uncertainty relations, algebra deformations, constraining of the maximal occupation number, shifting of the vacuum energy and renormalization of the charge and speed of propagation of field excitations. Furthermore, a compact field space is a natural way to implement the “Principle of finiteness” of physical theories, which once motivated the Born–Infeld theory. Thus the presented framework has a variety of potential applications in the theories of fundamental interactions (e.g. quantum gravity), as well as in condensed matter physics (e.g. continuous spin chains), and can shed new light on the issue of divergences in quantum field theories.
The Nonlinear Field Space Theory
Directory of Open Access Journals (Sweden)
Jakub Mielczarek
2016-08-01
Full Text Available In recent years the idea that not only the configuration space of particles, i.e. spacetime, but also the corresponding momentum space may have nontrivial geometry has attracted significant attention, especially in the context of quantum gravity. The aim of this letter is to extend this concept to the domain of field theories, by introducing field spaces (i.e. phase spaces of field values that are not affine spaces. After discussing the motivation and general aspects of our approach we present a detailed analysis of the prototype (quantum Nonlinear Field Space Theory of a scalar field on the Minkowski background. We show that the nonlinear structure of a field space leads to numerous interesting predictions, including: non-locality, generalization of the uncertainty relations, algebra deformations, constraining of the maximal occupation number, shifting of the vacuum energy and renormalization of the charge and speed of propagation of field excitations. Furthermore, a compact field space is a natural way to implement the “Principle of finiteness” of physical theories, which once motivated the Born–Infeld theory. Thus the presented framework has a variety of potential applications in the theories of fundamental interactions (e.g. quantum gravity, as well as in condensed matter physics (e.g. continuous spin chains, and can shed new light on the issue of divergences in quantum field theories.
Nonlinear field space cosmology
Mielczarek, Jakub; Trześniewski, Tomasz
2017-08-01
We consider the FRW cosmological model in which the matter content of the Universe (playing the role of an inflaton or quintessence) is given by a novel generalization of the massive scalar field. The latter is a scalar version of the recently introduced nonlinear field space theory, where the physical phase space of a given field is assumed to be compactified at large energies. For our analysis, we choose the simple case of a field with the spherical phase space and endow it with the generalized Hamiltonian analogous to the XXZ Heisenberg model, normally describing a system of spins in condensed matter physics. Subsequently, we study both the homogenous cosmological sector and linear perturbations of such a test field. In the homogenous sector, we find that nonlinearity of the field phase space is becoming relevant for large volumes of the Universe and can lead to a recollapse, and possibly also at very high energies, leading to the phase of a bounce. Quantization of the field is performed in the limit where the nontrivial nature of its phase space can be neglected, while there is a nonvanishing contribution from the Lorentz symmetry breaking term of the Hamiltonian. As a result, in the leading order of the XXZ anisotropy parameter, we find that the inflationary spectral index remains unmodified with respect to the standard case but the total amplitude of perturbations is subject to a correction. The Bunch-Davies vacuum state also becomes appropriately corrected. The proposed new approach is bringing cosmology and condensed matter physics closer together, which may turn out to be beneficial for both disciplines.
Teodorescu-Soare, C. T.; Dimitriu, D. G.; Ionita, C.; Schrittwieser, R. W.
2016-03-01
By negatively biasing a metallic grid with a small hole, down to a critical value of the applied potential a complex space-charge structure appears inside and around the grid cathode. The static current-voltage characteristic of the discharge shows one or two current jumps (the number of current jumps depending on the working gas pressure), one of them being of hysteretic type. Electrical probe measurements show a positive potential inside the grid cathode with respect to the potential applied on it. This is interpreted as being due to the hollow cathode effect. Thus, the inner fireball appears around the virtual anode inside the grid cathode. For more negative potentials, the electrons inside the cathode reach sufficient energy to penetrate the inner sheath near the cathode, passing through the hole and giving rise to a second fireball-like structure located outside the cathode. This second structure interacts with the negative glow of the discharge. The recorded time series of the discharge current oscillations reveal strongly nonlinear dynamics of the complex space-charge structure: by changing the negative potential applied on the grid cathode, the structure passes through different dynamic states involving chaos, quasi-periodicity, intermittency and period-doubling bifurcations, appearing like a competition of different routes to chaos.
Longitudinal Phase Space Tomography with Space Charge
Hancock, S; Lindroos, M
2000-01-01
Tomography is now a very broad topic with a wealth of algorithms for the reconstruction of both qualitative and quantitative images. In an extension in the domain of particle accelerators, one of the simplest algorithms has been modified to take into account the non-linearity of large-amplitude synchrotron motion. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The method is a hybrid one which incorporates particle tracking. Hitherto, a very simple tracking algorithm has been employed because only a brief span of measured profile data is required to build a snapshot of phase space. This is one of the strengths of the method, as tracking for relatively few turns relaxes the precision to which input machine parameters need to be known. The recent addition of longitudinal space charge considerations as an optional refinement of the code is described. Simplicity suggested an approach based on the derivative of bunch shape with the properties of...
Longitudinal phase space tomography with space charge
Hancock, S.; Lindroos, M.; Koscielniak, S.
2000-12-01
Tomography is now a very broad topic with a wealth of algorithms for the reconstruction of both qualitative and quantitative images. In an extension in the domain of particle accelerators, one of the simplest algorithms has been modified to take into account the nonlinearity of large-amplitude synchrotron motion. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The method is a hybrid one which incorporates particle tracking. Hitherto, a very simple tracking algorithm has been employed because only a brief span of measured profile data is required to build a snapshot of phase space. This is one of the strengths of the method, as tracking for relatively few turns relaxes the precision to which input machine parameters need to be known. The recent addition of longitudinal space charge considerations as an optional refinement of the code is described. Simplicity suggested an approach based on the derivative of bunch shape with the properties of the vacuum chamber parametrized by a single value of distributed reactive impedance and by a geometrical coupling coefficient. This is sufficient to model the dominant collective effects in machines of low to moderate energy. In contrast to simulation codes, binning is not an issue since the profiles to be differentiated are measured ones. The program is written in Fortran 90 with high-performance Fortran extensions for parallel processing. A major effort has been made to identify and remove execution bottlenecks, for example, by reducing floating-point calculations and recoding slow intrinsic functions. A pointerlike mechanism which avoids the problems associated with pointers and parallel processing has been implemented. This is required to handle the large, sparse matrices that the algorithm employs. Results obtained with and without the inclusion of space charge are presented and compared for proton beams in the CERN protron synchrotron booster. Comparisons
Discreteness of Point Charge in Nonlinear Electrodynamics
Breev, A I
2016-01-01
We consider two point charges in electrostatic interaction between them within the framework of a nonlinear model, associated with QED, that provides finiteness of their field energy. We argue that if the two charges are equal to each other the repulsion force between them disappears when they are infinitely close to each other, but remains as usual infinite if their values are different. This implies that within any system to which such a model may be applicable the point charge is fractional, it may only be $2^n$-fold of a certain fundamental charge, n=0,1,2... We find the common field of the two charges in a dipole approximation, where the separation between them is much smaller than the observation distance.
Classical BRST charge for nonlinear algebras
Buchbinder, I L
2007-01-01
We study the construction of the classical nilpotent canonical BRST charge for the nonlinear gauge algebras where a commutator (in terms of Poisson brackets) of the constraints is a finite order polynomial of the constraints. Such a polynomial is characterized by the coefficients forming a set of higher order structure constants. Assuming the set of constraints to be linearly independent, we find the restrictions on the structure constants when the nilpotent BRST charge can be written in a simple and universal form. In the case of quadratically nonlinear algebras we find the expression for third order contribution in the ghost fields to the BRST charge without the use of any additional restrictions on the structure constants.
Space Charge Modulated Electrical Breakdown
Li, Shengtao; Zhu, Yuanwei; Min, Daomin; Chen, George
2016-09-01
Electrical breakdown is one of the most important physical phenomena in electrical and electronic engineering. Since the early 20th century, many theories and models of electrical breakdown have been proposed, but the origin of one key issue, that the explanation for dc breakdown strength being twice or higher than ac breakdown strength in insulating materials, remains unclear. Here, by employing a bipolar charge transport model, we investigate the space charge dynamics in both dc and ac breakdown processes. We demonstrate the differences in charge accumulations under both dc and ac stresses and estimate the breakdown strength, which is modulated by the electric field distortion induced by space charge. It is concluded that dc breakdown initializes in the bulk whereas ac breakdown initializes in the vicinity of the sample-electrode interface. Compared with dc breakdown, the lower breakdown strength under ac stress and the decreasing breakdown strength with an increase in applied frequency, are both attributed to the electric field distortion induced by space charges located in the vicinity of the electrodes.
Some nonlinear space decomposition algorithms
Energy Technology Data Exchange (ETDEWEB)
Tai, Xue-Cheng; Espedal, M. [Univ. of Bergen (Norway)
1996-12-31
Convergence of a space decomposition method is proved for a general convex programming problem. The space decomposition refers to methods that decompose a space into sums of subspaces, which could be a domain decomposition or a multigrid method for partial differential equations. Two algorithms are proposed. Both can be used for linear as well as nonlinear elliptic problems and they reduce to the standard additive and multiplicative Schwarz methods for linear elliptic problems. Two {open_quotes}hybrid{close_quotes} algorithms are also presented. They converge faster than the additive one and have better parallelism than the multiplicative method. Numerical tests with a two level domain decomposition for linear, nonlinear and interface elliptic problems are presented for the proposed algorithms.
Charge quantization in the CP(1) nonlinear σ-model
Energy Technology Data Exchange (ETDEWEB)
Hellerman, Simeon, E-mail: simeon.hellerman.1@gmail.com; Kehayias, John, E-mail: john.kehayias@ipmu.jp; Yanagida, Tsutomu T., E-mail: tsutomu.tyanagida@ipmu.jp
2014-01-20
We investigate the consistency conditions for matter fields coupled to the four-dimensional (N=1 supersymmetric) CP(1) nonlinear sigma model (the coset space SU(2){sub G}/U(1){sub H}). We find that consistency requires that the U(1){sub H} charge of the matter be quantized, in units of half of the U(1){sub H} charge of the Nambu–Goldstone (NG) boson, if the matter has a nonsingular kinetic term and the dynamics respect the full group SU(2){sub G}. We can then take the linearly realized group U(1){sub H} to comprise the weak hypercharge group U(1){sub Y} of the Standard Model. Thus we have charge quantization without a Grand Unified Theory (GUT), completely avoiding problems like proton decay, doublet–triplet splitting, and magnetic monopoles. We briefly investigate the phenomenological implications of this model-building framework. The NG boson is fractionally charged and completely stable. It can be naturally light, avoiding constraints while being a component of dark matter or having applications in nuclear physics. We also comment on the extension to other NLSMs on coset spaces, which will be explored more fully in a followup paper.
Space charge emission in cylindrical diode
Energy Technology Data Exchange (ETDEWEB)
Torres-Córdoba, Rafael; Martínez-García, Edgar [Universidad Autónoma de Cd. Juárez-IIT, Cd. Juárez, Chihuahua, México (Mexico)
2014-02-15
In this paper, a mathematical model to describe cylindrical electron current emissions through a physics approximation method is presented. The proposed mathematical approximation consists of analyzing and solving the nonlinear Poisson's equation, with some determined mathematical restrictions. Our findings tackle the problem when charge-space creates potential barrier that disable the steady-state of the beam propagation. In this problem, the potential barrier effects of electron's speed with zero velocity emitted through the virtual cathode happens. The interaction between particles and the virtual cathode have been to find the inter-atomic potentials as boundary conditions from a quantum mechanics perspective. Furthermore, a non-stationary spatial solution of the electrical potential between anode and cathode is presented. The proposed solution is a 2D differential equation that was linearized from the generalized Poisson equation. A single condition was used solely, throughout the radial boundary conditions of the current density formation.
Charge Quantization in the CP(1) Nonlinear Sigma-Model
Hellerman, Simeon; Yanagida, Tsutomu T
2013-01-01
We investigate the consistency conditions for matter fields coupled to the four-dimensional (N = 1 supersymmetric) CP(1) nonlinear sigma model (the coset space SU(2)_G/U(1)_H). We find that consistency requires that the U(1)_H charge of the matter be quantized, in units of half of the U(1)_H charge of the Nambu-Goldstone (NG) boson, if the matter has a nonsingular kinetic term and the dynamics respect the full group SU(2)_G. We can then take the linearly realized group U(1)_H to comprise the weak hypercharge group U(1)_Y of the Standard Model. Thus we have charge quantization without a Grand Unified Theory (GUT), completely avoiding problems like proton decay, doublet-triplet splitting, and magnetic monopoles. We briefly investigate the phenomenological implications of this model-building framework. The NG boson is fractionally charged and completely stable. It can be naturally light, avoiding constraints while being a component of dark matter or having applications in nuclear physics. We also comment on the ...
Space charge compensation in low energy proton beams
Ismail, A B; Uriot, D; Pichoff, N
2004-01-01
High power accelerators are being studied for several projects including accelerator driven neutron or neutrino sources. The low energy part of these facilities has to be carefully optimized to match the beam requirements of the higher energy parts. In this low energy part, the space charge self force, induced by a high intensity beam, has to be carefully managed. This nonlinear force can generate a high irreversible emittance growth of the beam. To reduce space charge effects, neutralization of the beam charge can be done by capturing some particles of the ionised residual gas in the vacuum chamber. This space charge compensation (SCC) regime complicates the dynamic study. Modelling the beam behaviour in such regime would be a significant contribution to the development of high intensity accelerators. Numerical and experimental study of SCC is in progress on the Saclay High Intensity Proton Injector. Experimental measurements and 2D/3D simulations of proton beam SCC will be presented.
Space charge studies in FFAG using the tracking code Zgoubi
Energy Technology Data Exchange (ETDEWEB)
Tahar, M. Haj [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tsoupas, N. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2015-05-03
A method is implemented in Zgoubi that allows the computation of space charge effects in 2D distributions and with some restrictions in 3D distributions. It relies on decomposing field maps or analytical elements into slices and applying a space charge kick to the particles. The aim of this study is to investigate the accuracy of this technique, its limitations/advantages by comparisons with other linear/nonlinear computation methods and codes, and to apply it to high power fixed field ring design studies.
Space charge fields in DC cables
DEFF Research Database (Denmark)
McAllister, Iain Wilson; Crichton, George C; Pedersen, Aage
1996-01-01
The space charge that accumulates in DC cables can, mathematically, be resolved into two components. One is related to the temperature and the other to the magnitude of the electric field strength. Analytical expressions for the electric fields arising from each of these space charge components a...
Nonlinear approximation in alpha-modulation spaces
DEFF Research Database (Denmark)
Borup, Lasse; Nielsen, Morten
2006-01-01
The α-modulation spaces are a family of spaces that contain the Besov and modulation spaces as special cases. In this paper we prove that brushlet bases can be constructed to form unconditional and even greedy bases for the α-modulation spaces. We study m -term nonlinear approximation with brushlet...... bases, and give complete characterizations of the associated approximation spaces in terms of α-modulation spaces....
Improving Charging-Breeding Simulations with Space-Charge Effects
Bilek, Ryan; Kwiatkowski, Ania; Steinbrügge, René
2016-09-01
Rare-isotope-beam facilities use Highly Charged Ions (HCI) for accelerators accelerating heavy ions and to improve measurement precision and resolving power of certain experiments. An Electron Beam Ion Trap (EBIT) is able to create HCI through successive electron impact, charge breeding trapped ions into higher charge states. CBSIM was created to calculate successive charge breeding with an EBIT. It was augmented by transferring it into an object-oriented programming language, including additional elements, improving ion-ion collision factors, and exploring the overlap of the electron beam with the ions. The calculation is enhanced with the effects of residual background gas by computing the space charge due to charge breeding. The program assimilates background species, ionizes and charge breeds them alongside the element being studied, and allows them to interact with the desired species through charge exchange, giving fairer overview of realistic charge breeding. Calculations of charge breeding will be shown for realistic experimental conditions. We reexamined the implementation of ionization energies, cross sections, and ion-ion interactions when charge breeding.
Space curves, anholonomy and nonlinearity
Indian Academy of Sciences (India)
Radha Balakrishnan
2005-04-01
Using classical differential geometry, we discuss the phenomenon of anholonomy that gets associated with a static and a moving curve. We obtain the expressions for the respective geometric phases in the two cases and interpret them. We show that there is a close connection between anholonomy and nonlinearity in a wide class of nonlinear systems.
Nonlinear Oscillators in Space Physics
Lester,Daniel; Thronson, Harley
2011-01-01
We discuss dynamical systems that produce an oscillation without an external time dependent source. Numerical results are presented for nonlinear oscillators in the Em1h's atmosphere, foremost the quasi-biennial oscillation (QBOl. These fluid dynamical oscillators, like the solar dynamo, have in common that one of the variables in a governing equation is strongly nonlinear and that the nonlinearity, to first order, has particular form. of 3rd or odd power. It is shown that this form of nonlinearity can produce the fundamental li'equency of the internal oscillation. which has a period that is favored by the dynamical condition of the fluid. The fundamental frequency maintains the oscillation, with no energy input to the system at that particular frequency. Nonlinearities of 2nd or even power could not maintain the oscillation.
Space Charge Mitigation by Hollow Bunches
Oeftiger, AO
2014-01-01
To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.
Non-Linear Relativity in Position Space
Kimberly, D; Medeiros-Neto, J F; Kimberly, Dagny; Magueijo, João; Medeiros, João
2003-01-01
We propose two methods for obtaining the dual of non-linear relativity as previously formulated in momentum space. In the first we allow for the (dual) position space to acquire a non-linear representation of the Lorentz group independently of the chosen representation in momentum space. This requires a non-linear definition for the invariant contraction between momentum and position spaces. The second approach, instead, respects the linearity of the invariant contraction. This fully fixes the dual of momentum space and dictates a set of energy-dependent space-time Lorentz transformations. We discuss a variety of physical implications that would distinguish these two strategies. We also show how they point to two rather distinct formulations of theories of gravity with an invariant energy and/or length scale.
Longitudinal Space Charge in the SPS
Lasheen, Alexandre
2016-01-01
Longitudinal instabilities due to the SPS beam coupling impedance are a major issue for future projects and it is essential to have an accurate SPS impedance model to study them. The longitudinal space charge effect can be modelled by a pure reactive impedance and should also be included in simulations as it may have an impact at low energy. In this Note, the effect of the longitudinal space charge in the SPS is evaluated by taking into account the variation of the transverse beam size and vacuum chamber geometry along the ring. Scaling laws are used to investigate what are the most important parameters for the evaluation of the longitudinal space charge impedance.
Analyzing Affect of Image Charge in Space Charge Effect
Institute of Scientific and Technical Information of China (English)
ZhangXueying; XuHushan; JiaFei; LiWenfei
2003-01-01
There is an increasing requirement of high injection current and highly charged ion beams for accelerators at many laboratories, such as CERN, GSI, GANIL and IMP, with the development of super-conducting ECR source in recent.years. In this case, the space charge effect becomes a major concern when the beam current is as high as tens of mA. In fact, the faradic field induced by the image charges will be come into the metallic surfaces while the beams are transported in a vacuum tube or in between two plates. In order to ensure studying the space charge effect in reason, it is necessary to investigate the effect from such a field.
The micro maps description of a beam with space charge
Energy Technology Data Exchange (ETDEWEB)
Bergamini, F.; Turchetti, G. [Istituto Nazionale di Fisica Nucleare, Bologna (Italy). Dipt. di Fisica; Franchetti, G. [GSI, Darmstadt (Germany)
1999-05-01
In high-intensity accelerators the dominant nonlinear forces are due the space charge but the effect of the multipolar errors and synchro-betatron coupling should be taken into account. The micro maps approach allows, for a linear lattice, to iteratively obtain the self-consistent solution and can be extended to include the lattice nonlinearities. The authors investigate here the convergence of the method for a constant focusing and a FODO cell. In both cases we prove the convergence to the exact solution up to a limit current corresponding to a significant limit tune shift.
Nonlinear charge transport in bipolar semiconductors due to electron heating
Energy Technology Data Exchange (ETDEWEB)
Molina-Valdovinos, S., E-mail: sergiom@fisica.uaz.edu.mx [Universidad Autónoma de Zacatecas, Unidad Académica de Física, Calzada Solidaridad esq. Paseo, La Bufa s/n, CP 98060, Zacatecas, Zac, México (Mexico); Gurevich, Yu.G. [Centro de Investigación y de Estudios Avanzados del IPN, Departamento de Física, Av. IPN 2508, México D.F., CP 07360, México (Mexico)
2016-05-27
It is known that when strong electric field is applied to a semiconductor sample, the current voltage characteristic deviates from the linear response. In this letter, we propose a new point of view of nonlinearity in semiconductors which is associated with the electron temperature dependence on the recombination rate. The heating of the charge carriers breaks the balance between generation and recombination, giving rise to nonequilibrium charge carriers concentration and nonlinearity. - Highlights: • A new mechanism of nonlinearity of current-voltage characteristic (CVC) is proposed. • The hot electron temperature violates the equilibrium between electrons and holes. • This violation gives rise to nonequilibrium concentration of electrons and holes. • This leads to nonlinear CVC (along with the heating nonlinearity).
Transverse Mode Coupling Instability with Space Charge
Balbekov, V
2016-01-01
Transverse mode coupling instability of a bunch with space charge and wake field is considered in frameworks of the boxcar model. Eigenfunctions of the bunch without wake are used as the basis for solution of the equations with the wake field included. Dispersion equation for the bunch eigentunes is obtained in the form of an infinite continued fraction. It is shown that influence of space charge on the instability essentially depends on the wake sign. In particular, threshold of the negative wake increases in absolute value until the space charge tune shift is rather small, and goes to zero at higher space charge. The explanation of this behavior is developed by analysis of the bunch spectrum. A comparison of the results with published articles is represented.
Transverse Mode Coupling Instability with Space Charge
Energy Technology Data Exchange (ETDEWEB)
Balbekov, V. [Fermilab
2016-03-11
Transverse mode coupling instability of a bunch with space charge and wake field is considered in frameworks of the boxcar model. Eigenfunctions of the bunch without wake are used as the basis for solution of the equations with the wake field included. Dispersion equation for the bunch eigentunes is obtained in the form of an infinite continued fraction. It is shown that influence of space charge on the instability essentially depends on the wake sign. In particular, threshold of the negative wake increases in absolute value until the space charge tune shift is rather small, and goes to zero at higher space charge. The explanation of this behavior is developed by analysis of the bunch spectrum. A comparison of the results with published articles is represented.
Self-excitation of space charge waves
DEFF Research Database (Denmark)
Lyuksyutov, Sergei; Buchhave, Preben; Vasnetsov, Mikhail
1997-01-01
We report a direct observation of space charge waves in photorefractive crystals with point group 23 (sillenites) based on their penetration into an area with uniform light illumination. It is shown experimentally that the quality factor of the waves increases substantially with respect to what...... current theory predicts [B. Sturman el al., Appl. Phys. A 55, 235 (1992)]. This results in the appearance of strong spontaneous beams caused by space charge wave self-excitation....
Lagrangian Space Nonlinear $E$-mode clustering
Yu, Hao-Ran; Zhu, Hong-Ming
2016-01-01
We study the nonlinear $E$-mode clustering in Lagrangian space by using large scale structure (LSS) $N$-body simulations and use the displacement field information in Lagrangian space to recover the primordial linear density field. We find that, compared to Eulerian nonlinear density fields, the $E$-mode displacement fields in Lagrangian space improves the cross-correlation scale $k$ with initial density field by factor of 6 $\\sim$ 7, containing 2 orders of magnitude more primordial information. This illustrates ability of potential density reconstruction algorithms, to improve the baryonic acoustic oscillation (BAO) measurements from current and future large scale structure surveys.
Internal space charge measurement of materials in a space environment
Griseri, V.; Fukunaga, K.; Maeno, T.; Payan, D.; Laurent, C.; Levy, L.
2003-09-01
The charging/discharging effect produced by space environment on space vehicles are known but not fully identified yet. Experiments performed in laboratory in vacuum chamber that simulates spatial environment and the most realistic charge condition occurring in space have been developed in the last past forty years. A very small Pulse Electro-Acoustic space charge detection unit (mini-PEA) that can be mounted in a vacuum chamber, to measure internal space charges of materials in-situ during the irradiation has been developed. Several materials used in spatial environment such as Teflon®, and Kapton ® films on addition to PMMA films have been studied. The comparison and the good agreement between measured and calculated depth of penetration for electrons of given energy depending on the material nature contribute in the validation of the detection system and encourage us for further studies and development.
Survey of International Space Station Charging Events
Craven, P. D.; Wright, Kenneth H., Jr.; Minow, Joseph I.; Coffey, Victoria N.; Schneider, Todd A.; Vaughn, Jason A.; Ferguson, Dale C.; Parker, Linda N.
2009-01-01
With the negative grounding of the 160V Photovoltaic (PV) arrays, the International Space Station (ISS) can experience varied and interesting charging events. Since August 2006, there has been a multi-probe p ackage, called the Floating Potential Measurement Unit (FPMU), availa ble to provide redundant measurements of the floating potential of th e ISS as well as the density and temperature of the local plasma environment. The FPMU has been operated during intermittent data campaigns since August 2006 and has collected over 160 days of information reg arding the charging of the ISS as it has progressed in configuration from one to three PV arrays and with various additional modules such as the European Space Agency?s Columbus laboratory and the Japan Aeros pace Exploration Agency's Kibo laboratory. This paper summarizes the charging of the ISS and the local environmental conditions that contr ibute to those charging events, both as measured by the FPMU.
Study of longitudinal dynamics in space-charge dominated beams
Tian, Kai
Modern accelerator applications, such as heavy ion fusion drivers, pulsed neutron sources, electron injectors for high-energy linear colliders, and X-ray Free Electron Lasers, demand beams with high intensity, low emittance and small energy spread. At low (non-relativistic) energies, the "electrostatic", collective interactions from space-charge forces existing in such intense beams play the dominant role; we characterize these beams as space-charge dominated beams. This dissertation presents numerous new findings on the longitudinal dynamics of a space-charge dominated beam, particularly on the propagation of density perturbations. In order to fully understand the complex physics of longitudinal space-charge waves, we combine the results of theory, computer simulation, and experiment. In the Long Solenoid Experimental system (LSE), with numerous diagnostic tools and techniques, we have, for the first time, experimentally measured the detailed energy profiles of longitudinal space-charge waves at different locations, both near the beam source and at the end of the transport system. Along with the current profiles, we have a complete set of experimental data for the propagation of space-charge waves. We compare these measured results to a 1-D theory and find better agreement for beams with perturbations in the linear regime, where the perturbation strength is less than 10%, than those with nonlinear perturbations. Using fast imaging techniques that we newly developed, we have, for the first time, obtained the progressive time-resolved images of longitudinal slices of a space-charge dominated beam. These images not only provide us time-resolved transverse density distribution of the beam, but also enable us to take time-resolved transverse phase space measurement using computerized tomography. By combining this information with the longitudinal energy measurement, we have, for the first time, experimentally constructed the full 6-D phase space. Part of the results
Space Charge Mitigation With Longitudinally Hollow Bunches
Oeftiger, Adrian; Rumolo, Giovanni
2016-01-01
Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.
Space Charge Mitigation With Longitudinally Hollow Bunches
Oeftiger, Adrian; Rumolo, Giovanni; CERN. Geneva. ATS Department
2016-01-01
Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.
Nonextensivity, Complexity and Nonlinearity in Space Plasmas
Pavlos, G. P.
2017-01-01
Experimental time series, extracted from many and different space plasma systems corresponding to, solar wind, magnetospheric and other space plasma systems reveal common dynamical, geometrical, or statistical characteristics. Such characteristics are the low dimensionality, the typical intermittent turbulence multifractality, the temporal or spatial multiscale correlations and power laws scale invariance, non Gaoussianity and others. This universal aspect of experimental time series profiles was understood in the past as the chaos or SOC universality. However, after two or three decades of theoretical development in understanding of the nonlinearity and complexity, we can give a more compact theoretical description of the underline universal physical processes that produce the experimental time series complexity. Finally, in this study, we present and explain the modern complex set of theoretical concepts from the point of view of physics as the unification theory of nonlinear theory of non-equilibrium plasma systems as well as the presupposed theoretical framework of time series analysis of space plasma charachteristics.
Space charges can significantly affect the dynamics of accelerator maps
Bountis, Tassos; Skokos, Charalampos
2006-10-01
Space charge effects can be very important for the dynamics of intense particle beams, as they repeatedly pass through nonlinear focusing elements, aiming to maximize the beam's luminosity properties in the storage rings of a high energy accelerator. In the case of hadron beams, whose charge distribution can be considered as “frozen” within a cylindrical core of small radius compared to the beam's dynamical aperture, analytical formulas have been recently derived [C. Benedetti, G. Turchetti, Phys. Lett. A 340 (2005) 461] for the contribution of space charges within first order Hamiltonian perturbation theory. These formulas involve distribution functions which, in general, do not lead to expressions that can be evaluated in closed form. In this Letter, we apply this theory to an example of a charge distribution, whose effect on the dynamics can be derived explicitly and in closed form, both in the case of 2-dimensional as well as 4-dimensional mapping models of hadron beams. We find that, even for very small values of the “perveance” (strength of the space charge effect) the long term stability of the dynamics changes considerably. In the flat beam case, the outer invariant “tori” surrounding the origin disappear, decreasing the size of the beam's dynamical aperture, while beyond a certain threshold the beam is almost entirely lost. Analogous results in mapping models of beams with 2-dimensional cross section demonstrate that in that case also, even for weak tune depressions, orbital diffusion is enhanced and many particles whose motion was bounded now escape to infinity, indicating that space charges can impose significant limitations on the beam's luminosity.
Space charges can significantly affect the dynamics of accelerator maps
Energy Technology Data Exchange (ETDEWEB)
Bountis, Tassos [Department of Mathematics, University of Patras, GR-26500 Patras (Greece) and Center for Research and Applications of Nonlinear Systems (CRANS), University of Patras, GR-26500 Patras (Greece)]. E-mail: tassos50@otenet.gr; Skokos, Charalampos [Center for Research and Applications of Nonlinear Systems (CRANS), University of Patras, GR-26500 Patras (Greece)
2006-10-09
Space charge effects can be very important for the dynamics of intense particle beams, as they repeatedly pass through nonlinear focusing elements, aiming to maximize the beam's luminosity properties in the storage rings of a high energy accelerator. In the case of hadron beams, whose charge distribution can be considered as 'frozen' within a cylindrical core of small radius compared to the beam's dynamical aperture, analytical formulas have been recently derived [C. Benedetti, G. Turchetti, Phys. Lett. A 340 (2005) 461] for the contribution of space charges within first order Hamiltonian perturbation theory. These formulas involve distribution functions which, in general, do not lead to expressions that can be evaluated in closed form. In this Letter, we apply this theory to an example of a charge distribution, whose effect on the dynamics can be derived explicitly and in closed form, both in the case of 2-dimensional as well as 4-dimensional mapping models of hadron beams. We find that, even for very small values of the 'perveance' (strength of the space charge effect) the long term stability of the dynamics changes considerably. In the flat beam case, the outer invariant 'tori' surrounding the origin disappear, decreasing the size of the beam's dynamical aperture, while beyond a certain threshold the beam is almost entirely lost. Analogous results in mapping models of beams with 2-dimensional cross section demonstrate that in that case also, even for weak tune depressions, orbital diffusion is enhanced and many particles whose motion was bounded now escape to infinity, indicating that space charges can impose significant limitations on the beam's luminosity.
Charged anisotropic matter with linear or nonlinear equation of state
Varela, Victor; Ray, Saibal; Chakraborty, Kaushik; Kalam, Mehedi
2010-01-01
Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplification achieved with the introduction of electric charge were noticed as well. We deal with self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations. In order to discuss analytical solutions we extend Krori and Barua's method to include pressure anisotropy and linear or non-linear equations of state. The field equations are reduced to a system of three algebraic equations for the anisotropic pressures as well as matter and electrostatic energy densities. Attention is paid to compact sources characterized by positive matter density and positive radial pressure. Arising solutions satisfy the energy conditions of general relativity. Spheres with vanishing net charge contain fluid elements with unbounded proper charge density located at the fluid-vacuum interface. Notably the...
The structure of XLPE and the distribution of space charge
Institute of Scientific and Technical Information of China (English)
LI; Jixiao(李吉晓); ZHANG; Yewen(张冶文); ZHENG; Feihu(郑飞虎); WU; Changshun(吴长顺); XIA; Zhongfu(夏钟福)
2003-01-01
The formation and accumulation of space charge under charge treatment are investigated using PWP method. The interaction between space charge and the structure of XLPE is measured using infrared spectroscopy (IR) method. The related mechanism about space charge distribution and the structure of XLPE are discussed.
Control of nonlinear flexible space structures
Shi, Jianjun
With the advances made in computer technology and efficiency of numerical algorithms over last decade, the MPC strategies have become quite popular among control community. However, application of MPC or GPC to flexible space structure control has not been explored adequately in the literature. The work presented in this thesis primarily focuses on application of GPC to control of nonlinear flexible space structures. This thesis is particularly devoted to the development of various approximate dynamic models, design and assessment of candidate controllers, and extensive numerical simulations for a realistic multibody flexible spacecraft, namely, Jupiter Icy Moons Orbiter (JIMO)---a Prometheus class of spacecraft proposed by NASA for deep space exploratory missions. A stable GPC algorithm is developed for Multi-Input-Multi-Output (MIMO) systems. An end-point weighting (penalty) is used in the GPC cost function to guarantee the nominal stability of the closed-loop system. A method is given to compute the desired end-point state from the desired output trajectory. The methodologies based on Fake Algebraic Riccati Equation (FARE) and constrained nonlinear optimization, are developed for synthesis of state weighting matrix. This makes this formulation more practical. A stable reconfigurable GPC architecture is presented and its effectiveness is demonstrated on both aircraft as well as spacecraft model. A representative in-orbit maneuver is used for assessing the performance of various control strategies using various design models. Different approximate dynamic models used for analysis include linear single body flexible structure, nonlinear single body flexible structure, and nonlinear multibody flexible structure. The control laws evaluated include traditional GPC, feedback linearization-based GPC (FLGPC), reconfigurable GPC, and nonlinear dissipative control. These various control schemes are evaluated for robust stability and robust performance in the presence of
Weak non-linear surface charging effects in electrolytic films
Dean, D. S.; Horgan, R. R.
2002-01-01
A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full non-linear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the reno...
Space charge and screening in bilayer graphene
Kolomeisky, Eugene B.; Straley, Joseph P.; Abrams, Daniel L.
2016-11-01
Undoped bilayer graphene is a two-dimensional semimetal with a low-energy excitation spectrum that is parabolic in the momentum. As a result, the screening of an arbitrary external charge Ze is accompanied by a reconstruction of the ground state: valence band electrons (for Z > 0) are promoted to form a space charge around the charge while the holes leave the physical picture. The outcome is a flat neutral object resembling the regular atom except that for Z\\gg 1 it is described by a strictly linear Thomas-Fermi theory. This theory also predicts that the bilayer’s static dielectric constant is the same as that of a two-dimensional electron gas in the long-wavelength limit.
Weak nonlinear surface-charging effects in electrolytic films.
Dean, D S; Horgan, R R
2003-11-01
A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full nonlinear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the renormalization of the theory and apply it to a triple-layer model for a thin film with Stern layer of thickness h. For this model we give expressions for the surface charge sigma(L) and the disjoining pressure P(d)(L) and show their dependence on the parameters. The influence of image charges naturally arises in the formalism, and we show that predictions depend strongly on h because of their effects. In particular, we show that the surface charge vanishes as the film thickness L-->0. The fluctuation terms in this class of theories contribute a Casimir-like attraction across the film. Although this attraction is well known to be negligible compared with the mean-field component for model electrolytic films with no surface-charge regulation, in the model studied here these fluctuations also affect the surface-charge regulation leading to a fluctuation component in the disjoining pressure which has the same behavior as the mean-field component even for large film thickness.
Parametric Landau damping of space charge modes
Macridin, Alexandru; Stern, Eric; Amundson, James; Spentzouris, Panagiotis
2016-01-01
Landau damping is the mechanism of plasma and beam stabilization; it is caused by energy transfer from collective modes to incoherent motion of resonant particles. Normally this resonance requires the wave frequency in the particle frame to match the resonant particles frequency. Using the Synergia modeling package to study transverse coherent modes of bunched beams with space charge, we have identified a new kind of damping mechanism, parametric Landau damping, driven by the modulation of the wave-particle interaction.
Photoelectric Charging of Dust in Space
Sickafoose, A. A.; Robertson, S.; Colwell, J. E.; Horanyi, M.
1999-09-01
Illumination of surfaces in space by solar ultraviolet light produces photoelectrons which form a plasma sheath near the surface. Dust particles on the surface can acquire a charge and be transported horizontally and vertically by electric fields within the sheath. On the moon, suspended dust grains have been observed on multiple occasions, and there is evidence for horizontal lunar dust transport. Photoelectron production and dust particle charging are also expected to be significant near the surface of Mars. Understanding the photoelectric charging properties of dust can help explain the observed dynamics of lunar dust and help predict the behavior of dust on surfaces of planetary satellites, asteroids, planetary ring particles, and planetesimals. In addition, any human or spacecraft activity on planetary bodies is affected by dust dynamics near the surface. We have examined the photoelectric charging of dust dropped through UV illumination and dust dropped past a UV illuminated surface having a photoelectron sheath. Experiments are performed in vacuum with illumination from a 1 kW Hg-Xe arc lamp. The lamp produces a spectrum down to ~ 200 nm ( ~ 6.2 eV), and the photoemitter is a 12 cm diameter zirconium plate. Dust dropped through UV illumination loses electrons due to photoemission, while dust dropped past an illuminated surface gains electrons from the photoelectron sheath. Initial results are consistent with expected charge calculated from the work function of the materials, the energy of incoming photons, and the capacitance of the grains. Photoelectric charging experiments have been done for several different kinds of dust 90-106 mu m in diameter. We will present the results of these experiments and compare the charging properties of zinc, copper, graphite, Martian regolith simulant (JSC Mars-1), lunar regolith simulant (JSC-1), and lunar soil from an Apollo 17 sample. This research is supported by NASA.
Transverse Schottky spectra and beam transfer functions of coasting ion beams with space charge
Energy Technology Data Exchange (ETDEWEB)
Paret, Stefan
2010-02-22
A study of the transverse dynamics of coasting ion beams with moderate space charge is presented in this work. From the dispersion relation with linear space charge, an analytic model describing the impact of space charge on transverse beam transfer functions (BTFs) and the stability limits of a beam is derived. The dielectric function obtained in this way is employed to describe the transverse Schottky spectra with linear space charge as well. The difference between the action of space charge and impedances is highlighted. The setup and the results of an experiment performed in the heavy ion synchrotron SIS-18 at GSI to detect space-charge effects at different beam intensities are explicated. The measured transverse Schottky spectra and BTFs are compared with the linear space-charge model. The stability diagrams constructed from the BTFs are presented. The space-charge parameters evaluated from the Schottky and BTF measurements are compared with estimations based on measured beam parameters. The impact of collective effects on the Schottky and BTF diagnostics is also investigated through numerical simulations. For this purpose the self-field of beams with linear and non-linear transverse density-distributions is computed on a twodimensional grid. The noise of the random particle distribution causes fluctuations of the dipole moment of the beam which produce the Schottky spectrum. BTFs are simulated by exciting the beam with transverse kicks. The simulation results are used to verify the space-charge model. (orig.)
Processing Approach of Non-linear Adjustment Models in the Space of Non-linear Models
Institute of Scientific and Technical Information of China (English)
LI Chaokui; ZHU Qing; SONG Chengfang
2003-01-01
This paper investigates the mathematic features of non-linear models and discusses the processing way of non-linear factors which contributes to the non-linearity of a nonlinear model. On the basis of the error definition, this paper puts forward a new adjustment criterion, SGPE.Last, this paper investigates the solution of a non-linear regression model in the non-linear model space and makes the comparison between the estimated values in non-linear model space and those in linear model space.
Nonlinear evolution and final fate of (charged) superradiant instability
Bosch, Pablo; Lehner, Luis
2016-01-01
We describe the full nonlinear development of the superradiant instability for a charged massless scalar field, coupled to general relativity and electromagnetism, in the vicinity of a Reissner--Nordstr\\"om-AdS black hole. The presence of the negative cosmological constant provides a natural context for considering perfectly reflecting boundary conditions and studying the dynamics as the scalar field interacts repeateadly with the black hole. At early times, small superradiant perturbations grow as expected from linearized studies. Backreaction then causes the black hole to lose charge and mass until the perturbation becomes nonsuperradiant, with the final state described by a stable hairy black hole. For large gauge coupling, the instability extracts a large amount of charge per unit mass, resulting in greater entropy increase. We discuss the implications of the observed behavior for the general problem of superradiance in black hole spacetimes.
Nonlinear fluorescence probe using photoinduced charge separation (Presentation Recording)
Mochizuki, Kentaro; Shi, Lanting; Mizukami, Shin; Yamanaka, Masahito; Tanabe, Mamoru; Gong, Wei-Tao; Palonpon, Almar F.; Kawano, Shogo; Kawata, Satoshi; Kikuchi, Kazuya; Fujita, Katsumasa
2015-08-01
Two-photon excitation microscopy (TPEM) provides spatial resolution beyond the optical diffraction limit using the nonlinear response of fluorescent molecules. One of the strong advantages of TPEM is that it can be performed using a laser-scanning microscope without a complicated excitation method or computational post-processing. However, TPEM has not been recognized as a super-resolution microscopy due to the use of near-infrared light as excitation source, which provides lower resolution than visible light. In our research, we aimed for the realization of nonlinear fluorescence response with visible light excitation to perform super-resolution imaging using a laser-scanning microscope. The nonlinear fluorescence response with visible light excitation is achieved by developing a probe which provides stepwise two-photon excitation through photoinduced charge separation. The probe named nitro-bisBODIPY consists of two fluorescent molecules (electron donor: D) and one electron acceptor (A), resulting to the structure of D-A-D. Excited by an incident photon, nitro-bisBODIPY generates a charge-separated pair between one of the fluorescent molecules and the acceptor. Fluorescence emission is obtained only when one more incident photon is used to excite the other fluorescent molecule of the probe in the charge-separated state. This stepwise two-photon excitation by nitro-bisBODIPY was confirmed by detection of the 2nd order nonlinear fluorescence response using a confocal microscope with 488 nm CW excitation. The physical model of the stepwise two-photon excitation was investigated by building the energy diagram of nitro-bisBODIPY. Finally, we obtained the improvement of spatial resolution in fluorescence imaging of HeLa cells using nitro-bisBODIPY.
Analysis of beam envelope by transverse space charge effect
Energy Technology Data Exchange (ETDEWEB)
Toyama, Shin`ichi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center
1997-09-01
It is important for high current accelerators to estimate the contribution of the space charge effect to keep the beam off its beak up. The application of an envelope equation is examined in previous report in which the beam is just coasting beam (non accelerating). The analysis of space charge effect is necessary for the comparison in coming accelerator test in PNC. In order to evaluate the beam behavior in high current, the beam dynamics and beam parameters which are input to the equation for the evaluation are developed and make it ready to estimate the beam transverse dynamics by the space charge. The estimate needs to have enough accuracy for advanced code calculation. After the preparation of the analytic expression of transverse motion, the non-linear differential equation of beam dynamics is solved by a numerical method on a personal computer. The beam envelope from the equation is estimated by means of the beam emittance, current and energy. The result from the analysis shows that the transverse beam broadening is scarecely small around the beam current value of PNC design. The contribution to the beam broadening of PNC linac comes from its beam emittance. The beam broadening in 100 MeV case is almost negligible in the view of transverse space charge effect. Therefore, the electron beam is stable up to 10 A order in PNC linac design. Of course, the problem for RF supply is out of consideration here. It is important to estimate other longitudinal effect such as beam bunch effect which is lasting unevaluated. (author)
Charge Exchange Effect on Space-Charge-Limited Current Densities in Ion Diode
Institute of Scientific and Technical Information of China (English)
石磊
2002-01-01
The article theoretically studied the charge-exchange effects on space charge limited electron and ion current densities of non-relativistic one-dimensional slab ion diode, and compared with those of without charge exchange.
Thermodynamics of charged black holes with a nonlinear electrodynamics source
González, Hernán A.; Hassaïne, Mokhtar; Martínez, Cristián
2009-11-01
We study the thermodynamical properties of electrically charged black hole solutions of a nonlinear electrodynamics theory defined by a power p of the Maxwell invariant, which is coupled to Einstein gravity in four and higher spacetime dimensions. Depending on the range of the parameter p, these solutions present different asymptotic behaviors. We compute the Euclidean action with the appropriate boundary term in the grand canonical ensemble. The thermodynamical quantities are identified and, in particular, the mass and the charge are shown to be finite for all classes of solutions. Interestingly, a generalized Smarr formula is derived and it is shown that this latter encodes perfectly the different asymptotic behaviors of the black hole solutions. The local stability is analyzed by computing the heat capacity and the electrical permittivity and we find that a set of small black holes is locally stable. In contrast to the standard Reissner-Nordström solution, there is a first-order phase transition between a class of these nonlinear charged black holes and the Minkowski spacetime.
Introduction to Space Charge Effects in Semiconductors
Böer, Karl W
2010-01-01
This book is the most comprehensive one to describe the basics of space-charge effects in semiconductors, starting from basic principles to advanced application in semiconducting devices. It uses detailed analyses of the transport, Poisson, and continuity equations to demonstrate the behavior of the solution curves of the complete set of field and current distributions, along with quantitative descriptions of the relevant band models of typical pn-junction and Schottky barrier devices. It emphasizes the relevance to actual devices and sets these results apart from more simple models of networks of diodes and resistors. The book is especially important for people interested in detail analysis of solar cells and their efficiencies.
Nonlinear relaxation field in charged systems under high electric fields
Energy Technology Data Exchange (ETDEWEB)
Morawetz, K
2000-07-01
The influence of an external electric field on the current in charged systems is investigated. The results from the classical hierarchy of density matrices are compared with the results from the quantum kinetic theory. The kinetic theory yields a systematic treatment of the nonlinear current beyond linear response. To this end the dynamically screened and field-dependent Lenard-Balescu equation is integrated analytically and the nonlinear relaxation field is calculated. The classical linear response result known as Debye - On-Sager relaxation effect is only obtained if asymmetric screening is assumed. Considering the kinetic equation of one specie the other species have to be screened dynamically while the screening with the same specie itself has to be performed statically. Different other approximations are discussed and compared. (author)
Moderately nonlinear diffuse-charge dynamics under an ac voltage
Stout, Robert F.; Khair, Aditya S.
2015-09-01
The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of Vo/(kBT /e ) , where Vo is the amplitude of the driving voltage and kBT /e is the thermal voltage with kB as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D /λDL , where D is the ion diffusivity, λD is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O (Vo3) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in Vo. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing Vo. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer.
Space charge physics for particle accelerators
Hofmann, Ingo
2017-01-01
Understanding and controlling the physics of space charge effects in linear and circular proton and ion accelerators are essential to their operation, and to future high-intensity facilities. This book presents the status quo of this field from a theoretical perspective, compares analytical approaches with multi-particle computer simulations and – where available – with experiments. It discusses fundamental concepts of phase space motion, matched beams and modes of perturbation, along with mathematical models of analysis – from envelope to Vlasov-Poisson equations. The main emphasis is on providing a systematic description of incoherent and coherent resonance phenomena; parametric instabilities and sum modes; mismatch and halo; error driven resonances; and emittance exchange due to anisotropy, as well as the role of Landau damping. Their distinctive features are elaborated in the context of numerous sample simulations, and their potential impacts on beam quality degradation and beam loss are discussed....
Thermodynamics of charged black holes with a nonlinear electrodynamics source
Gonzalez, Hernan A; Martinez, Cristian
2009-01-01
We study the thermodynamical properties of electrically charged black hole solutions of a nonlinear electrodynamics theory defined by a power p of the Maxwell invariant, which is coupled to Einstein gravity in four and higher spacetime dimensions. Depending on the range of the parameter p, these solutions present different asymptotic behaviors. We compute the Euclidean action with the appropriate boundary term in the grand canonical ensemble. The thermodynamical quantities are identified and in particular, the mass and the charge are shown to be finite for all classes of solutions. Interestingly, a generalized Smarr formula is derived and it is shown that this latter encodes perfectly the different asymptotic behaviors of the black hole solutions. The local stability is analyzed by computing the heat capacity and the electrical permittivity and we find that a set of small black holes are locally stable. In contrast to the standard Reissner-Nordstrom solution, there is a first-order phase transition between a ...
Impact of mechanical deformation on space charge in XLPE
Chen, G; Kamaruzzaman, M. R.
2007-01-01
In this paper we report the effect of mechanical deformation on space charge dynamics in crosslinked polyethylene. Thin films were peeled from a 66 kV commercial XLPE cable. Space charge measurements under dc electric fields have been monitored using the pulsed electroacoustic (PEA) technique. It has been found that charge dynamics in deformed XLPE are different from that from undeformed XLPE at lower voltages. At low applied electric field, space charge is dominated by heterocharge in the de...
Emitter space charge layer transit time in bipolar junction transistors
Rustagi, S. C.; Chattopadhyaya, S. K.
1981-04-01
The charge defined emitter space charge layer transit times of double diffused transistors have been calculated using a regional approach, and compared with the corresponding base transit times. The results obtained for emitter space-charge layer transit times have been discussed with reference to the capacitance analysis of Morgan and Smit (1960) for graded p-n junctions.
Space charge limited conduction in CdSe thin films
Indian Academy of Sciences (India)
Pradip Kr Kalita; B K Sarma; H L Das
2003-10-01
The current ()–voltage () characteristics of thermally evaporated CdSe thin films having thickness in the range 850–3000 Å and deposited within the substrate temperature of 303–573 K show nearly linear dependence at low voltage and afterwards a non-linear behaviour at higher voltage range. A detailed study of – curves in dark and under illumination clearly reveals the mechanism as ohmic at low voltage and that of trap limited space charge limited conduction (SCLC) at higher voltage. The transition voltage () from ohmic to SCLC is found to be quite independent of ambient temperature as well as intensity of illumination. SCLC is explained on the basis of the exponential trap distribution in CdSe films. Trap depths estimated from the ln vs 103/T plots are found to be within 0.60–0.37 eV. Using the relevant SCLC theory, the carrier concentration, 0, total trap concentration, t, and the ratio of free charge to trapped charge, , have been calculated and correlated with ambient temperature and intensity of illumination.
Nonlinear delta f Simulations of Collective Effects in Intense Charged Particle Beams
Hong Qi
2003-01-01
A nonlinear delta(f) particle simulation method based on the Vlasov-Maxwell equations has been recently developed to study collective processes in high-intensity beams, where space-charge and magnetic self-field effects play a critical role in determining the nonlinear beam dynamics. Implemented in the Beam Equilibrium, Stability and Transport (BEST) code [H. Qin, R.C. Davidson, and W.W. Lee, Physical Review -- Special Topics on Accelerator and Beams 3 (2000) 084401; 3 (2000) 109901.], the nonlinear delta(f) method provides a low-noise and self-consistent tool for simulating collective interactions and nonlinear dynamics of high-intensity beams in modern and next-generation accelerators and storage rings, such as the Spallation Neutron Source and heavy ion fusion drivers. A wide range of linear eigenmodes of high-intensity charged-particle beams can be systematically studied using the BEST code. Simulation results for the electron-proton two-stream instability in the Proton Storage Ring experiment [R. Macek, ...
Weakly nonlinear electrophoresis of a highly charged colloidal particle
Schnitzer, Ory; Zeyde, Roman; Yavneh, Irad; Yariv, Ehud
2013-05-01
At large zeta potentials, surface conduction becomes appreciable in thin-double-layer electrokinetic transport. In the linear weak-field regime, where this effect is quantified by the Dukhin number, it is manifested in non-Smoluchowski electrophoretic mobilities. In this paper we go beyond linear response, employing the recently derived macroscale model of Schnitzer and Yariv ["Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction," Phys. Rev. E 86, 021503 (2012), 10.1103/PhysRevE.86.021503] as the infrastructure for a weakly nonlinear analysis of spherical-particle electrophoresis. A straightforward perturbation in the field strength is frustrated by the failure to satisfy the far-field conditions, representing a non-uniformity of the weak-field approximation at large distances away from the particle, where salt advection becomes comparable to diffusion. This is remedied using inner-outer asymptotic expansions in the spirit of Acrivos and Taylor ["Heat and mass transfer from single spheres in Stokes flow," Phys. Fluids 5, 387 (1962), 10.1063/1.1706630], with the inner region representing the particle neighborhood and the outer region corresponding to distances scaling inversely with the field magnitude. This singular scheme furnishes an asymptotic correction to the electrophoretic velocity, proportional to the applied field cubed, which embodies a host of nonlinear mechanisms unfamiliar from linear electrokinetic theories. These include the effect of induced zeta-potential inhomogeneity, animated by concentration polarization, on electro-osmosis and diffuso-osmosis; bulk advection of salt; nonuniform bulk conductivity; Coulomb body forces acting on bulk volumetric charge; and the nonzero electrostatic force exerted upon the otherwise screened particle-layer system. A numerical solution of the macroscale model validates our weakly nonlinear analysis.
Space Charge Modules for PyHEADTAIL
Oeftiger, Adrian
2016-01-01
PyHEADTAIL is a 6D tracking tool developed at CERN to simulate collective effects. We present recent developments of the direct space charge (SC) suite, which is available for both the CPU and GPU. A new 3D particle-in-cell solver with open boundary conditions has been implemented. For the transverse plane, there is a semi-analytical Bassetti-Erskine model as well as 2D self-consistent particle-in-cell solvers with both open and closed boundary conditions. For the longitudinal plane, PyHEADTAIL offers line density derivative models. Simulations with these models are benchmarked with experiments at the injection plateau of CERN’s SPS.
Space Charge Modules for PyHEADTAIL
Oeftiger, Adrian; Hegglin, Stefan Eduard
2016-01-01
PyHEADTAIL is a 6D tracking tool developed at CERN to simulate collective effects. We present recent developments of the direct space charge suite, which is available for both the CPU and GPU. A new 3D particle-in-cell solver with open boundary conditions has been implemented. For the transverse plane, there is a semi-analytical Bassetti-Erskine model as well as 2D self-consistent particle-in-cell solvers with both open and closed boundary conditions. For the longitudinal plane, PyHEADTAIL offers line density derivative models. Simulations with these models are benchmarked with experiments at the injection plateau of CERN’s Super Proton Synchrotron.
Dielectric sample with two-layer charge distribution for space charge calibration purposes
DEFF Research Database (Denmark)
Holbøll, Joachim; Henriksen, Mogens; Rasmussen, C.
2002-01-01
In the present paper is described a dielectric test sample with two very narrow concentrations of bulk charges, achieved by two internal electrodes not affecting the acoustical properties of the sample, a fact important for optimal application of most space charge measuring systems. Space charge...
Bhattacharyya, S.; De, Simanta
2016-09-01
The impact of the solid polarization of a charged dielectric particle in gel electrophoresis is studied without imposing a weak-field or a thin Debye length assumption. The electric polarization of a dielectric particle due to an external electric field creates a non-uniform surface charge density, which in turn creates a non-uniform Debye layer at the solid-gel interface. The solid polarization of the particle, the polarization of the double layer, and the electro-osmosis of mobile ions within the hydrogel medium create a nonlinear effect on the electrophoresis. We have incorporated those nonlinear effects by considering the electrokinetics governed by the Stokes-Brinkman-Nernst-Planck-Poisson equations. We have computed the governing nonlinear coupled set of equations numerically by adopting a finite volume based iterative algorithm. Our numerical method is tested for accuracy by comparing with several existing results on free-solution electrophoresis as well as results based on the Debye-Hückel approximation. Our computed result shows that the electrophoretic velocity decreases with the rise of the particle dielectric permittivity constant and attains a saturation limit at large values of permittivity. A significant impact of the solid polarization is found in gel electrophoresis compared to the free-solution electrophoresis.
Exact solutions of SO(3) non-linear sigma model in a conic space background
Bezerra, V B; Romero, C
2005-01-01
We consider a nonlinear sigma model coupled to the metric of a conic space. We obtain restrictions for a nonlinear sigma model to be a source of the conic space. We then study nonlinear sigma model in the conic space background. We find coordinate transformations which reduce the chiral fields equations in the conic space background to field equations in Minkowski spacetime. This enables us to apply the same methods for obtaining exact solutions in Minkowski spacetime to the case of a conic spacetime. In the case the solutions depend on two spatial coordinates we employ Ivanov's geometrical ansatz. We give a general analysis and also present classes of solutions in which there is dependence on three and four coordinates. We discuss with special attention the intermediate instanton and meron solutions and their analogous in the conic space. We find differences in the total actions and topological charges of these solutions and discuss the role of the deficit angle.
Nonlinear interaction of charged particles with strong laser pulses in a magnetic undulator
Directory of Open Access Journals (Sweden)
H. K. Avetissian
2010-08-01
Full Text Available Laser acceleration due to the nonlinear-threshold phenomena of charged particle “reflection” and capture by slowed wave in a magnetic undulator is considered. The obtained numerical results prove the particle reflection and capture phenomena in the field of actual laser pulses with temporal and space profiles which lead to the particles acceleration. In contrast to the reflection regime where particle acceleration takes place already at the constant undulator step, in the capture regime it is necessary to increase adiabatically the undulator step along the laser pulse propagation direction by the certain self-consistent variation law corresponding to acceleration rate.
Charged relativistic fluids and non-linear electrodynamics
Dereli, T.; Tucker, R. W.
2010-01-01
The electromagnetic fields in Maxwell's theory satisfy linear equations in the classical vacuum. This is modified in classical non-linear electrodynamic theories. To date there has been little experimental evidence that any of these modified theories are tenable. However with the advent of high-intensity lasers and powerful laboratory magnetic fields this situation may be changing. We argue that an approach involving the self-consistent relativistic motion of a smooth fluid-like distribution of matter (composed of a large number of charged or neutral particles) in an electromagnetic field offers a viable theoretical framework in which to explore the experimental consequences of non-linear electrodynamics. We construct such a model based on the theory of Born and Infeld and suggest that a simple laboratory experiment involving the propagation of light in a static magnetic field could be used to place bounds on the fundamental coupling in that theory. Such a framework has many applications including a new description of the motion of particles in modern accelerators and plasmas as well as phenomena in astrophysical contexts such as in the environment of magnetars, quasars and gamma-ray bursts.
Energy Technology Data Exchange (ETDEWEB)
Rane, R., E-mail: ramu@ipr.res.in; Ranjan, M.; Mukherjee, S. [FCIPT, Institute for Plasma Research, Gandhinagar-382044 (India); Bandyopadhyay, M. [ITER-India, Institute for Plasma Research, Gandhinagar-382044 (India)
2016-01-15
The combined effect of magnetic field (B), gas pressure (P), and the corresponding discharge voltage on the discharge properties of argon in inverted cylindrical magnetron has been investigated. In the experiment, anode is biased with continuous 10 ms sinusoidal half wave. It is observed that at a comparatively higher magnetic field (i.e., >200 gauss) and lower operating pressure (i.e., <1 × 10{sup −3} mbar), the discharge extinguishes and demands a high voltage to reignite. Discharge current increases with increase in magnetic field and starts reducing at sufficiently higher magnetic field for a particular discharge voltage due to restricted electron diffusion towards the anode. It is observed that B/P ratio plays an important role in sustaining the discharge and is constant for a discharge voltage. The discharge is transformed to negative space charge regime from positive space charge regime at certain B/P ratio and this ratio varies linearly with the discharge voltage. The space charge reversal is indicated by the radial profile of the floating potential and plasma potential in between two electrodes for different magnetic fields. At a particular higher magnetic field (beyond 100 gauss), the floating potential increases gradually with the radial distance from cathode, whereas it remains almost constant at lower magnetic field.
A Space Charge Compensation Study of Low Energy Hydrogen Ion Beams
Ben-Ismail, A; Uriot, D; Pichoff, Nicolas
2005-01-01
High-power accelerators are being studied for several projects including accelerator driven neutron or neutrino sources. The low energy part of these facilities has to be carefully optimized to match the beam requirements of the higher energy parts. The complexity of high intensity beam dynamics in the low energy line is essentially due to the non-linear space charge effects. The PIC code CARTAGO* has been developed in order to simulate the beam transport at low energy including the temporal evolution effects of the space charge compensation. This paper relates the structure and the numerical methods of a 2D (r,z) new version of the code. The effects of the longitudinal space charge, the image charge and external 2D (r,z) magnetic field were included. The results of H+
Charged fluid distribution in higher dimensional spheroidal space-time
Indian Academy of Sciences (India)
G P Singh; S Kotambkar
2005-07-01
A general solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space-time geometry.
Modelling space-charge limited transport in discotic liquid crystals
Lever, L.; Bushby, R. J.; Kelsall, R. W.
2006-05-01
Using a self-consistent Monte Carlo/Poisson algorithm, we investigate space-charge limited conduction in discotic liquid crystal time of flight (TOF) experiments. The charge transport mechanism is via a semi-delocalised banding process, and two mechanisms of photo-generation of charge carriers are considered: excitons generated by the laser pulse, which quench at the anode, and processes, such as the Onsager mechanism, that lead to direct generation of free electron/hole pairs within the bulk. The nature of the space-charge limited TOF transient is investigated as a function of quantum yield of charge carriers and as a function of applied potential.
Formation of the Surface Space Charge Layer in Fair Weather
Redin, Alexander; Kupovykh, Gennady; Boldyreff, Anton
2014-05-01
It is widely known that the positive space charge, caused by electrode effect action, is obtained near surface in fair weather. Space charge density depends on the different local features: meteorological conditions, aerosol particles concentration, convective transfer of the surface layer. Namely space charge determines the local variations of electric field. Space charge could be negative in condition of strong ionization rate in thin air layer near surface. The electrodynamic model, consisting of transfer equations of light ions and nucleuses, generated by interactions between lights ions and aerosol particles, and Poisson equation. The turbulent transfer members, electric field near the surface, the mobility of positive and negative ions, recombination coefficient, ionization rate, the number of elementary charges on the nuclei were took into account in the model equations. The time-space variations of positive and negative small and heavy ions, electric field, electrical conductivity, current density and space charge, depending on aerosol particles concentrations, turbulence and convective transfer ionization rate, aerosol particles size and number of charged on the particles are calculated. The mechanisms of turbulent and convection-turbulent surface layer electrodynamic structure forming in dependence of single and multi-charged aerosol particles for different physical and meteorological conditions are investigated. Increasing of turbulent mixing intensity leads to increasing of character electrode layer thickness, decreasing of space charge density value, decreasing of electric current conductivity value. The electrode effect of the whole layer remains constant. Increasing of aerosol particles concentration leads to decreasing of electrode effect within the whole electrode layer and increasing of electric field values, decreasing of space charge density values and current conductivity density. It was received that increasing of the aerosol particles
Understanding the effect of space charge on instabilities
Energy Technology Data Exchange (ETDEWEB)
Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Chao, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES); Chin, Y. H. [National Lab. for High Energy Physics (KEK), Ibaraki (Japan)
2015-05-03
The combined effect of space charge and wall impedance on transverse instabilities is an important consideration in the design and operation of high intensity hadron machines as well as an intrinsic academic interest. This study explores the combined effects of space charge and wall impedance using various simplified models in an attempt to produce a better understanding of their interplay.
Head-Tail Modes for Strong Space Charge
Energy Technology Data Exchange (ETDEWEB)
Burov, Alexey
2008-12-01
Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.
Valdeblànquez, Eder
2001-10-01
Eder Valdeblànquez,Universidad del Zulia,Apartado 4011-A 526,Maracaibo,Venezuela. ABSTRACT: In this paper by space charge effect in Langmuir probes are compared for different kind of symmetries; plane, cylindrical and spherical. A detailed analysis is performed here including temperature effects, and therefore kinetic theory is used instead of fluid equations as other authors. The strongly non-linear equations obtained here have been solved first by numerical analysis and later by approximations using Bessel functions. The accuracy of each approximaton is also discussed. Space Charge effects are important in plane geometries than in the case of cylindrical or spherical symmetries.
Space-charge dynamics of polymethylmethacrylate under electron beam irradiation
Gong, H; Ong, C K
1997-01-01
Space-charge dynamics of polymethylmethacrylate (PMMA) under electron beam irradiation has been investigated employing a scanning electron microscope. Assuming a Gaussian space-charge distribution, the distribution range (sigma) has been determined using a time-resolved current method in conjunction with a mirror image method. sigma is found to increase with irradiation time and eventually attain a stationary value. These observations have been discussed by taking into account radiation-induced conductivity and charge mobility. (author)
Domain wall stability in ferroelectrics with space charges
Energy Technology Data Exchange (ETDEWEB)
Zuo, Yinan, E-mail: zuo@mfm.tu-darmstadt.de; Genenko, Yuri A.; Klein, Andreas; Stein, Peter; Xu, Baixiang [Institute of Materials Science, Technische Universität Darmstadt, D-64287 Darmstadt (Germany)
2014-02-28
Significant effect of semiconductor properties on domain configurations in ferroelectrics is demonstrated, especially in the case of doped materials. Phase field simulations are performed for ferroelectrics with space charges due to donors and electronic charge carriers. The free charges introduced thereby can act as a source for charge compensation at domain walls with uncompensated polarization bound charges. Results indicate that the equilibrium position of a domain wall with respect to its rotation in a head-to-head or a tail-to-tail domain configuration depends on the charge defect concentration and the Fermi level position.
Nonlinear Conductivity and Collective Charge Excitations in the Lowest Landau Level
Auerbach, Assa; Arovas, Daniel P.
2017-07-01
For weakly disordered fractional quantum Hall phases, the nonlinear photoconductivity is related to the charge susceptibility of the clean system by a Floquet boost. Thus, it may be possible to probe collective charge modes at finite wave vectors by electrical transport. Incompressible phases, irradiated at slightly above the magnetoroton gap, are predicted to exhibit negative photoconductivity and zero resistance states with spontaneous internal electric fields. Nonlinear conductivity can probe composite fermions' charge excitations in compressible filling factors.
Space-Charge Waves and Instabilities in Intense Beams
Wang, J. G.
1997-11-01
Advancced accelerator applications, such as drivers for heavy ion inertial fusion, high-intensity synchrotrons for spallation neutron sources, high energy boosters, free electron lasers, high-power microwave generators, etc., require ever-increasing beam intensity. An important beam dynamics issue in such beams is the collective behavior of charged particles due to their space charge effects. This includes the phenomena of space-charge waves and instabilities excited on beams by external perturbations. It is very crucial to fully understand these phenomena in order to develop advanced accelerators for various applications. At the University of Maryland we have been conducting experimental programs to study space-charge waves and longitudinal instabilities by employing low-energy, high-current, space-charge dominated electron beams. Localized perturbations on the beams are generated from a gridded electron gun. In a conducting transport channel focused by short solenoids, these perturbations evolve into space-charge waves propagating on the beams. The wave speed is measured and many beam parameters are determined with this technique. The reflection of space-charge waves at the shoulder of an initially rectangular beam bunch is also observed. In a resistive-wall channel focused by a uniform long solenoid, the space-charge waves suffer longitudinal instability. The properties of the instabilities are studied in detail in the long wavelength range. In this talk we review our experimental results on the waves and instabilities and compare with theory.
A Null Space Approach for Solving Nonlinear Complementarity Problems
Institute of Scientific and Technical Information of China (English)
Pu-yan Nie
2006-01-01
In this work, null space techniques are employed to tackle nonlinear complementarity problems(NCPs). NCP conditions are transform into a nonlinear programming problem, which is handled by null space algorithms. The NCP conditions are divided into two groups. Some equalities and inequalities in an NCP are treated as constraints. While other equalities and inequalities in an NCP are to be regarded as objective function.Two groups are all updated in every step. Null space approaches are extended to nonlinear complementarity problems. Two different solvers are employed for an NCP in an algorithm.
Nonlinear regime-switching state-space (RSSS) models.
Chow, Sy-Miin; Zhang, Guangjian
2013-10-01
Nonlinear dynamic factor analysis models extend standard linear dynamic factor analysis models by allowing time series processes to be nonlinear at the latent level (e.g., involving interaction between two latent processes). In practice, it is often of interest to identify the phases--namely, latent "regimes" or classes--during which a system is characterized by distinctly different dynamics. We propose a new class of models, termed nonlinear regime-switching state-space (RSSS) models, which subsumes regime-switching nonlinear dynamic factor analysis models as a special case. In nonlinear RSSS models, the change processes within regimes, represented using a state-space model, are allowed to be nonlinear. An estimation procedure obtained by combining the extended Kalman filter and the Kim filter is proposed as a way to estimate nonlinear RSSS models. We illustrate the utility of nonlinear RSSS models by fitting a nonlinear dynamic factor analysis model with regime-specific cross-regression parameters to a set of experience sampling affect data. The parallels between nonlinear RSSS models and other well-known discrete change models in the literature are discussed briefly.
Dynamic space charge behaviour in polymeric DC cables
DEFF Research Database (Denmark)
Rasmussen, Claus Nygaard; Holbøll, Joachim; Henriksen, Mogens
2002-01-01
The use of extruded insulation for DC cables involves a risk of local electric field enhancement, caused by a space charge build-up within the dielectric. In this work, the theory of charge generation and transport in polymers is applied in a numerical computer model in order to predict the forma......The use of extruded insulation for DC cables involves a risk of local electric field enhancement, caused by a space charge build-up within the dielectric. In this work, the theory of charge generation and transport in polymers is applied in a numerical computer model in order to predict...
Nonlinear damped Schrodinger equation in two space dimensions
Directory of Open Access Journals (Sweden)
Tarek Saanouni
2015-04-01
Full Text Available In this article, we study the initial value problem for a semi-linear damped Schrodinger equation with exponential growth nonlinearity in two space dimensions. We show global well-posedness and exponential decay.
Chong, Y. L.; Chen, G.; Miyake, H.; Matsui, K.; Tanaka, Y.; Takada, T.
2006-04-01
This paper reports on the result of space charge evolution in cross-linked polyethylene (XLPE) planar samples approximately 220 µm thick. The space charge measurement technique used in this study is the pulsed electroacoustic method. There are two phases to this experiment. In the first phase, the samples were subjected to dc 30 kVdc mm-1 and ac (sinusoidal) electric stress levels of 30 kVpk mm-1 at frequencies of 1, 10 and 50 Hz ac. In addition, ac space charge under 30 kVrms mm-1 and 60 kVpk mm-1 electric stress at 50 Hz was also investigated. The volts-off results showed that the amount of charge trapped in XLPE sample under dc electric stress is significantly bigger than samples under ac stress even when the applied ac stresses are substantially higher. The second phase of the experiment involves studying the dc space charge evolution in samples that were tested under ac stress during the first phase of the experiment. Ac ageing causes positive charge to become more dominant over negative charge. It was also discovered that ac ageing creates deeper traps, particularly for negative charge. This paper also gives a brief overview of the data processing methods used to analyse space charge under ac electric stress.
Space Charge Effects and Limitations in the CERN Proton Synchrotron
Wasef, R; Damerau, H; Gilardoni, S; Hancock, S; Hernalsteens, C; Huschauer, A; Schmidt, F; Franchetti, G
2013-01-01
Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High- Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.
Geometry dependence of 2-dimensional space-charge-limited currents
De Visschere, Patrick
2016-01-01
The space-charge-limited current in a zero thickness planar thin film depends on the geometry of the electrodes. We present a theory which is to a large extent analytical and applicable to many different lay-outs. We show that a space-charge-limited current can only be sustained if the emitting electrode induces a singularity in the field and if the singularity induced by the collecting electrode is not too strong. For those lay-outs where no space-charge-limited current can be sustained for a zero thickness film, the real thickness of the film must be taken into account using a numerical model.
Singularity-free Bianchi spaces with nonlinear electrodynamics
García-Salcedo, R; Garcia-Salcedo, Ricardo; Breton, Nora
2004-01-01
In this paper we present the analysis to determine the existence of singularities in spatially homogeneous anisotropic universes filled with nonlinear electromagnetic radiation. These spaces are conformal to Bianchi spaces admitting a three parameter group of motions G$_3$. We study analytical extensions as well as geodesic completeness. It is shown that with nonlinear electromagnetic field some of the Bianchi spaces are geodesically complete, like G$_3$II and G$_3$VIII; however Bianchi G$_3$IX presents the phenomenon of geodesics that are imprisoned. In contrast, diagonal Bianchi spaces like G$_3$I, G$_3$III and Kantowski-Sachs have a finite time existence ending in a scalar polynomial curvature singularity.
Numerical simulation of amplification of space charge waves in n-InP films
Energy Technology Data Exchange (ETDEWEB)
Garcia-Barrientos, Abel, E-mail: abel@upp.edu.mx [Department of Mechatronics, Polytechnic University of Pachuca (UPP), Km. 20 Carretera Pachuca-Cd.Sahagun, Ex-Hacienda de Santa Barbara, 43830 Pachuca, Hidalgo (Mexico); Advanced Materials and Device Analysis Group, Inst. for Microelectronics, TU Wien, Gusshausstr. 27-29, 1040 Vienna (Austria); Palankovski, Vassil, E-mail: palankovski@iue.tuwien.ac.at [Advanced Materials and Device Analysis Group, Inst. for Microelectronics, TU Wien, Gusshausstr. 27-29, 1040 Vienna (Austria)
2011-10-25
The non-linear interaction of space charge waves including the amplification in microwave and millimeter wave range in n-InP films, possessing the negative differential conductance phenomenon, is investigated theoretically. Both the amplified signal and the generation of harmonics of the input signal are demonstrated, which are due to non-linear effect of the negative differential resistance. It is possible to observe an amplification of the space charge waves in n-InP films of submicron thicknesses at essentially higher frequencies f <70 GHz, when compared with n-GaAs films f < 44 GHz. The increment observed in the gain is due to the larger dynamic range in n-InP than in n-GaAs films.
Nonlinear Parabolic Equations with Singularities in Colombeau Vector Spaces
Institute of Scientific and Technical Information of China (English)
Mirjana STOJANOVI(C)
2006-01-01
We consider nonlinear parabolic equations with nonlinear non-Lipschitz's term and singular initial data like Dirac measure, its derivatives and powers. We prove existence-uniqueness theorems in Colombeau vector space gC1,w2,2([O,T),Rn),n ≤ 3. Due to high singularity in a case of parabolic equation with nonlinear conservative term we employ the regularized derivative for the conservative term, in order to obtain the global existence-uniqueness result in Colombeau vector space gC1,L2([O,T),Rn),n ≤ 3.
Early transverse decoherence of bunches with space charge
Karpov, Ivan; Kornilov, Vladimir; Boine-Frankenheim, Oliver
2016-12-01
The transverse decoherence of injected bunches is an important phenomenon in synchrotrons and storage rings. The initial stage of this process determines the transverse emittance blowup, which should be taken into account for the design of feedback systems, for example. The interplay of different high-intensity effects can strongly affect the initial decoherence stage. We present a model that explains decoherence and emittance growth with chromaticity, space charge, and image charges within the first synchrotron period. We compare the model for different combinations of parameters with self-consistent particle tracking simulations and measurements in the SIS18 synchrotron at GSI Darmstadt. Generally, space charge slows down the decoherence process and can cause the loss of decoherence. Chromaticity and image charges can partly compensate this loss and restore the decoherence. We also analyze the single-particle excitation driven by space charge during the decoherence process. Particles gain large amplitudes from the coherent beam oscillation, which leads to halo buildup and losses.
Nonlinear differentiation equation and analytic function spaces
Li, Hao; Li, Songxiao
2015-01-01
In this paper we consider the nonlinear complex differential equation $$(f^{(k)})^{n_{k}}+A_{k-1}(z)(f^{(k-1)})^{n_{k-1}}+\\cdot\\cdot\\cdot+A_{1}(z)(f')^{n_{1}}+A_{0}(z)f^{n_{0}}=0, $$where $ A_{j}(z)$, $ j=0, \\cdots, k-1 $, are analytic in the unit disk $ \\mathbb{D} $, $ n_{j}\\in R^{+} $ for all $ j=0, \\cdots, k $. We investigate this nonlinear differential equation from two aspects. On one hand, we provide some sufficient conditions on coefficients such that all solutions of this equation bel...
Space charge in linear accelerators workshop. [Eighteen papers
Energy Technology Data Exchange (ETDEWEB)
Jameson, R.A. (ed.)
1978-05-01
Nineteen papers and three summary sessions (theoretical, simulation codes, and experimental approach) are presented on the effects of space charge in linear accelerators. A separate abstract was prepared for each paper for inclusion in Energy Research Abstracts (ERA). (PMA)
WSN-Based Space Charge Density Measurement System.
Deng, Dawei; Yuan, Haiwen; Lv, Jianxun; Ju, Yong
2017-01-01
It is generally acknowledged that high voltage direct current (HVDC) transmission line endures the drawback of large area, because of which the utilization of cable for space charge density monitoring system is of inconvenience. Compared with the traditional communication network, wireless sensor network (WSN) shows advantages in small volume, high flexibility and strong self-organization, thereby presenting great potential in solving the problem. Additionally, WSN is more suitable for the construction of distributed space charge density monitoring system as it has longer distance and higher mobility. A distributed wireless system is designed for collecting and monitoring the space charge density under HVDC transmission lines, which has been widely applied in both Chinese state grid HVDC test base and power transmission projects. Experimental results of the measuring system demonstrated its adaptability in the complex electromagnetic environment under the transmission lines and the ability in realizing accurate, flexible, and stable demands for the measurement of space charge density.
Study on space charge effects of the CSNS/RCS
Institute of Scientific and Technical Information of China (English)
XU Shou-Yan; WANG Sheng
2011-01-01
The Rapid Cycling Synchrotron (RCS) is a key component of the China Spallation Neutron Source (CSNS).The space charge effect is one of the most important issues in the CSNS/RCS,which limits the maximum beam intensity,as well as the maximum beam power.Space charge effects are the main source of emittance growth and beam loss in the RCS.Space charge effects have been studied by simulation for the CSNS/RCS.By optimizing the painting orbit,the optimized painting distribution was obtained.The space charge effects during the acceleration are studied and dangerous resonances,which may induce emittance growth and beam loss,are investigated.The results are an important reference for the design and commissioning of the CSNS/RCS.
Space-charge limiting current in spherical cathode diodes
Institute of Scientific and Technical Information of China (English)
刘国治; 邵浩
2003-01-01
The results of the investigation on the space-charge limiting current for a spherical-cathode diode in the nonrelativistic situation are presented in this paper. The results show that the current enhancement factor equals the square of E-field enhancement factor on the cathode surface. The generated space-charge limiting current is deduced.In the case of a pin-shaped-cathode diode, the space-charge limiting current is also obtained, indicating that the current is independent of the geometric parameters of the diode. Analyses of the shielding effects and the conditions for generation of the uniform space-charge limiting beam show that, for pin-arrayed cathodes, the distance between pins should be in the range from 1.2D to 1.5D, where D is the distance between the two electrodes.
Conductivity and Space Charges in PE with Additives
DEFF Research Database (Denmark)
Holbøll, Joachim; Henriksen, Mogens; Hjerrild, J.
2003-01-01
Temperature dependent conductivity and space charge formation was measured in metallocene catalyst polymerized polyethylene samples of planar geometry with semiconductive electrodes. The temperature dependence of the conductivity was determined based on leakage current measurements at variable te...
Space Charge Effect in the Sheet and Solid Electron Beam
Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung
1998-11-01
We analyze the space charge effect of two different types of electron beam ; sheet and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for sheet and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting current and space charge loading in each geometries.
The effect of degassing on morphology and space charge
Chong, Y L; Chen, G; Ho, Y F F
2004-01-01
It is believed that space charge buildup in cross-linked polyethylene (XLPE) insulation is the main cause for premature failure of underground power cables. The space charge activities in XLPE depend on many factors such as additives, material treatment, ambient temperature, insulator/electrode interface, etc. Degassing is one of the material treatment process commonly employ in cable manufacturing to improve insulation performance. In this paper, investigation on the effect of degassing peri...
Space-Charge Compensation Options for the LHC Injector Complex
Aiba, M; Dorda, U; Franchetti, G; Garoby, R; Koutchouk, Jean-Pierre; Martini, M; Métral, E; Papaphilippou, Y; Scandale, Walter; Shiltsev, V; Zimmermann, F
2007-01-01
Space-charge effects have been identified as the most serious intensity limitation in the CERN PS and PS Booster, on the way towards ultimate LHC performance and beyond. We here explore the application of several previously proposed space-charge compensation methods to the two LHC pre-injector rings, and the challenges which need to be overcome. The methods considered include the reduction of tune shift and resonance strengths via octupoles, pole-face windings, electron lenses, or neutralisation.
Charge and longitudinal momentum distributions in transverse coordinate space
Mondal, Chandan; Dahiya, Harleen; Chakrabarti, Dipankar
2016-01-01
We investigate the charge distributions for the $u$ and $d$ quarks in transverse coordinate space in a light-front quark-diquark model for the nucleons using the overlaps of the wave functions constructed from the soft-wall AdS/QCD prediction. We have also obtained the charge distributions for proton and neutron in transverse coordinate space and compared it with the distributions obtained in impact-parameter space. Further, we study the longitudinal momentum distributions using the wave functions in the transverse coordinate space. We have also shown the explicit fermionic and bosonic contributions for different struck $u$ and $d$ quarks.
Simulations of beam emittance growth from the collectiverelaxation of space-charge nonuniformities
Energy Technology Data Exchange (ETDEWEB)
Lund, Steven M.; Grote, David P.; Davidson, Ronald C.
2004-05-01
Beams injected into a linear focusing channel typically have some degree of space-charge nonuniformity. For unbunched beams with high space-charge intensity propagating in linear focusing channels, Debye screening of self-field interactions tends to make the transverse density profile flat. An injected particle distribution with a large systematic charge nonuniformity will generally be far from an equilibrium of the focusing channel and the initial condition will launch a broad spectrum of collective modes. These modes can phase-mix and experience nonlinear interactions which result in an effective relaxation to a more thermal-equilibrium-like distribution characterized by a uniform density profile. This relaxation transfers self-field energy from the initial space-charge nonuniformity to the local particle temperature, thereby increasing beam phase space area (emittance growth). Here they employ two-dimensional electrostatic particle in cell (PIC) simulations to investigate the effects of initial transverse space-charge nonuniformities on the equality of beams with high space-charge intensity propagating in a continuous focusing channel. Results are compared to theoretical bounds of emittance growth developed in previous studies. Consistent with earlier theory, it is found that a high degree of initial distribution nonuniformity can be tolerated with only modest emittance growth and that beam control can be maintained. The simulations also provide information on the rate of relaxation and characteristic levels of fluctuations in the relaxed states. This research suggests that a surprising degree of initial space-charge nonuniformity can be tolerated in practical intense beam experiments.
Nonlinear dynamics for charges particle beams with a curved axis in the matrix - recursive model
Energy Technology Data Exchange (ETDEWEB)
Dymnikov, A.D. [University of St Petersburg, (Russian Federation). Institute of Computational Mathematics and Control Process
1993-12-31
In this paper a new matrix and recursive approach has been outlined for treating nonlinear optics of charged particle beams. This approach is a new analytical and computational tool for designers of optimal beam control systems. 9 refs.
Semi-analytic variable charge solitary waves involving dust phase-space vortices (holes)
Energy Technology Data Exchange (ETDEWEB)
Tribeche, Mouloud; Younsi, Smain; Amour, Rabia; Aoutou, Kamel [Plasma Physics Group, Faculty of Sciences-Physics, Theoretical Physics Laboratory, University of Bab-Ezzouar, USTHB BP 32, El Alia, Algiers 16111 (Algeria)], E-mail: mtribeche@usthb.dz
2009-09-15
A semi-analytic model for highly nonlinear solitary waves involving dust phase-space vortices (holes) is outlined. The variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate the localized structures that may occur in a dusty plasma with variable charge trapped dust particles. Our results which complement the previously published work on this problem (Schamel et al 2001 Phys. Plasmas 8 671) should be of basic interest for experiments that involve the trapping of dust particles in ultra-low-frequency dust acoustic modes.
Karmakar, P. K.; Borah, B.
2013-09-01
We try to present a theoretical evolutionary model leading to the excitations of nonlinear pulsational eigenmodes in a planar (1D) collisional dust molecular cloud (DMC) on the Jeans scale. The basis of the adopted model is the Jeans assumption of self-gravitating homogeneous uniform medium for simplification. It is a self-gravitating multi-fluid consisting of the Boltzmann distributed warm electrons and ions, and the inertial cold dust grains with partial ionization. Dust-charge fluctuations, convections and all the possible collisions are included. The grain-charge behaves as a dynamical variable owing mainly to the attachment of the electrons and ions to the grain-surfaces randomly. The adopted technique is centered around a mathematical model based on new solitary spectral patterns within the hydrodynamic framework. The collective dynamics of the patterns is governed by driven Korteweg-de Vries ( d-KdV) and Korteweg-de Vries (KdV) equations obtained by a standard multiscale analysis. Then, simplified analytical and numerical solutions are presented. The grain-charge fluctuation and collision processes play a key role in the DMC stability. The sensitive dependence of the eigenmode amplitudes on diverse relevant plasma parameters is discussed. The significance of the main results in astrophysical, laboratory and space environments are concisely summarized.
Huang, Z; Huang, Zheng; Suzuki, Mahiko
1996-01-01
We obtain the general analytic solutions of the nonlinear \\sigma-model in 3+1 dimensions as the candidates for the disoriented chiral condensate (DCC). The nonuniformly isospin-orientated solutions are shown to be related to the uniformly oriented ones through the chiral (axial) rotations. We discuss the pion charge distribution arising from these solutions. The distribution dP/df=1/(2\\sqrt{f}) holds for the uniform solutions in general and the nonuniform solutions in the 1+1 boost invariant case. For the nonuniform solution in 1+1 without a boost-invariance and in higher dimensions, the distribution does not hold in the integrated form. However, it is applicable to the pions selected from a small segment in the momentum phase space. We suggest that the nonuniform DCC's may correspond to the mini-Centauro events.
Longitudinal holes in debunched particle beams in storage rings, perpetuated by space-charge forces
Koscielniak, Shane Rupert; Lindroos, M
2001-01-01
Stationary, self-consistent, and localized longitudinal density perturbations on an unbunched charged-particle beam, which are solutions of the nonlinearized Vlasov-Poisson equation, have recently received some attention. In particular, we address the case that space charge is the dominant longitudinal impedance and the storage ring operates below transition energy so that the negative mass instability is not an explanation for persistent beam structure. Under the customary assumption of a bell-shaped steady-state distribution, about which the expansion is made, the usual wave theory of Keil and Schnell (1969) for perturbations on unbunched beams predicts that self-sustaining perturbations are possible only (below transition) if the impedance is inductive (or resistive) or if the bell shape is inverted. Space charge gives a capacitive impedance. Nevertheless, we report numerous experimental measurements made at the CERN Proton Synchrotron Booster that plainly show the longevity of holelike structures in coast...
Simulation of space charge effects in resistive plate chambers
Lippmann, Christian
2003-01-01
Multigap resistive plate chambers with 0.3-mm gas gaps operated in avalanche mode at atmospheric pressure have reached timing accuracies below 50 ps (standard deviation) with efficiencies above 99% . The avalanches in high homogeneous electric fields of 100 kV/cm are strongly influenced by space charge effects which are the main topic of this paper. We extend a previously discussed Monte Carlo simulation model of avalanches in resistive plate chambers by the dynamic calculation of the electric field in the avalanches. We complete the previously presented results on time resolution and efficiency data with simulated charge spectra. The simulated data shows good agreement with measurements. The detailed simulation of the avalanche saturation due to the space charge fields explains the small observed charges, the shape of the spectra, and the linear increase of average charges with high voltage. (22 refs).
Geometric properties of Banach spaces and nonlinear iterations
Chidume, Charles
2009-01-01
Nonlinear functional analysis and applications is an area of study that has provided fascination for many mathematicians across the world. This monograph delves specifically into the topic of the geometric properties of Banach spaces and nonlinear iterations, a subject of extensive research over the past thirty years. Chapters 1 to 5 develop materials on convexity and smoothness of Banach spaces, associated moduli and connections with duality maps. Key results obtained are summarized at the end of each chapter for easy reference. Chapters 6 to 23 deal with an in-depth, comprehensive and up-to-date coverage of the main ideas, concepts and results on iterative algorithms for the approximation of fixed points of nonlinear nonexpansive and pseudo-contractive-type mappings. This includes detailed workings on solutions of variational inequality problems, solutions of Hammerstein integral equations, and common fixed points (and common zeros) of families of nonlinear mappings. Carefully referenced and full of recent,...
The nonlinear standing wave inside the space of liquid
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Based on the basic equations of hydrodynamics, the nonlinear acoustic wave equation is obtained. By taking into account the boundary condition and properties of nonlinear standing wave, the equation is solved through perturbation method, and the stable expressions of fundamental wave and second harmonic are presented. The sound pressures in an ultrasonic cleaner are measured by hydrophones, and the relationship between the received voltages of hydrophones and the output voltages of the ultrasonic generator is researched. The study shows the existence of the nonlinear effect of liquid and analyzes the frequency spectrum of the received signals by hydrophones, by which the fundamental wave, second and high order harmonics are found coexisting in the bounded space filled with liquids. The theory and experimental results testify the existence of the nonlinear standing wave in liquid. Owing to the restricted applicability of perturbation method, the theoretical results of the fundamental wave and second harmonic are good only for the weak nonlinear phenomenon.
Emittance Measurements of Space Charge Dominated Electron Beam.
2014-09-26
measurement 2,3 have been introduced in the past, especially in particle accelerator physics. In free space, the envelope of a non -neutral charged...density no and thickness 2d is located on the y-axis. Let us assume that the velocity space distribution is a Maxwellian with a temperature T and the beam
Kato, Shinichi; Harada, Hiroyuki; Hotchi, Hideaki; Okabe, Kota; Yamamoto, Kazami; Kinsho, Michikazu
For high intensity proton accelerators, one of the beam loss sources is the incoherent tune spread caused by the space charge force. In the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, beams are injected sequentially and shifted slightly from the central orbit in order to increase the beam size intentionally and suppress the charge density and incoherent tune spread. This injection method has been adopted and suppressed the beam loss. However, simulations clarified that beams did not spread as much as expected because of the space charge effect in the high current case. As simulation results of the optimized beam shift pattern when the space charge effect is considered, it was obtained that the incoherent tune spread could be suppressed to an extent that has not been achieved previously.
Institute of Scientific and Technical Information of China (English)
Zhang Li-Ping; Xue Ju-Kui; Li Yan-Long
2011-01-01
Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles.A linear dispersion relation and a Korteweg-de VriesBurgers equation governing the dust acoustic shock waves are obtained.The relevance of the instability of wave and the wave evolution to the dust size distribution and nonadiabatic dust charge fluctuation is illustrated both analytically and numerically.The numerical results show that the Gaussian size distribution of dust particles and the nonadiabatic dust charge fluctuation have strong common influence on the propagation of both linear and nonlinear excitations.
Nonlinear Mirror Modes in Space Plasmas
Sulem, P -L
2011-01-01
Since the first observations by Kaufmann et al.\\ (1970), special attention has been paid to static pressure-balanced structures in the form of magnetic holes or humps observed in regions of the solar wind and of planetary magnetosheaths where the $\\beta$ parameter is relatively large and the ion perpendicular temperature exceeds the parallel one. Although alternative interpretations have been proposed, these structures are usually viewed as associated with the mirror instability discovered in 1957 by Vedenov and Sagdeev. After reviewing observational results provided by satellite missions, high-resolution numerical simulations of the Vlasov--Maxwell equations together with asymptotic and phenomenological models of the nonlinear dynamics near the instability threshold are discussed. The constraining effect of the mirror instability on the temperature anisotropy associated with a dominant perpendicular ion heating observed in the solar wind is reported, and recent simulations of this phenomenon based on an elab...
Using Space as a Nonlinear Plasma Laboratory
Papadopoulos, Konstantinos
2008-11-01
Ionospheric heaters have been an important tool of plasma physics investigations. The extent that non-linear plasma phenomena can be triggered and observed depends critically on the heater power, its Effective Radiative Power (ERP) and its scanning capability. Increasing these parameters allows us to reach thresholds associated with effects that were not previously observed. The latest entry to ionospheric heating, the HF transmitter associated with the High Frequency Active Ionospheric Research Program (HAARP) was completed in June 2007. The transmitter consists of 180 antenna elements spanning 30.6 acres and can radiate 3.6 MW of HF power (a factor of almost 4 higher than any previous heater) in the 2.8-10.0 MHz range. With increasing frequency the beam-width varies from 15-5 degrees, corresponding to 20-30 dB gain and resulting in ERP between 1-5 GW. The antenna can point to any direction in a cone 30 degrees from the vertical, with reposition time of 15 microseconds resulting in superluminal scanning speeds. The transmitter can synthesize essentially any waveform and transmit any polarization. These capabilities far exceed those of any previous heater and allow for new frontier research in non-linear plasma physics. The presentation will focus first on the relationship of the new capabilities of the facility with thresholds of physical processes that had not been achieved previously. It will then present new spectacular results that have been achieved during the last year. They include whistler injection and amplification, injection of shear and magnetosonic waves in the magnetosphere, Langmuir turbulence, upper hybrid waves and thermal instabilities, electron acceleration, optical emissions and formation of artificial ducts for whistler propagation. The presentation will also discuss future experiments made possible for the first time by the new transmitter capabilities, large bandwidth and high ERP.
DEFF Research Database (Denmark)
Lysenko, Alexander V.; Volk, Iurii I.; Serozhko, A.
2017-01-01
We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave (SCW) harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instab...
Space charge neutralization by electron-transparent suspended graphene.
Srisonphan, Siwapon; Kim, Myungji; Kim, Hong Koo
2014-01-20
Graphene possesses many fascinating properties originating from the manifold potential for interactions at electronic, atomic, or molecular levels. Here we report measurement of electron transparency and hole charge induction response of a suspended graphene anode on top of a void channel formed in a SiO2/Si substrate. A two-dimensional (2D) electron gas induced at the oxide interface emits into air and makes a ballistic transport toward the suspended graphene. A small fraction (>~0.1%) of impinging electrons are captured at the edge of 2D hole system in graphene, demonstrating good transparency to very low energy (graphene anode have the effect of neutralizing the electron space charge in the void channel. This charge compensation dramatically enhances 2D electron gas emission at cathode to the level far surpassing the Child-Langmuir's space-charge-limited emission.
Topological charge algebra of optical vortices in nonlinear interactions.
Zhdanova, Alexandra A; Shutova, Mariia; Bahari, Aysan; Zhi, Miaochan; Sokolov, Alexei V
2015-12-28
We investigate the transfer of orbital angular momentum among multiple beams involved in a coherent Raman interaction. We use a liquid crystal light modulator to shape pump and Stokes beams into optical vortices with various integer values of topological charge, and cross them in a Raman-active crystal to produce multiple Stokes and anti-Stokes sidebands. We measure the resultant vortex charges using a tilted-lens technique. We verify that in every case the generated beams' topological charges obey a simple relationship, resulting from angular momentum conservation for created and annihilated photons, or equivalently, from phase-matching considerations for multiple interacting beams.
Quantum theory of space charge limited current in solids
Energy Technology Data Exchange (ETDEWEB)
González, Gabriel, E-mail: gabriel.gonzalez@uaslp.mx [Cátedras Conacyt, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78000, Mexico and Coordinación para la Innovación y la Aplicación de la Ciencia y la Tecnología, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78000 (Mexico)
2015-02-28
We present a quantum model of space charge limited current transport inside trap-free solids with planar geometry in the mean field approximation. We use a simple transformation which allows us to find the exact analytical solution for the steady state current case. We use our approach to find a Mott-Gurney like behavior and the mobility for single charge carriers in the quantum regime in solids.
Analytical solutions for space charge fields in TPC drift volumes
Rossegger, S; Schnizer, B
2011-01-01
At high particle rates and high multiplicities, Time Projection Chambers can suffer from field distortions due to slow moving ions that accumulate within the drift volume. These variations modify the electron trajectory along the drift path, affecting the tracking performance of the detector. In order to calculate the track distortions due to an arbitrary space charge distribution in a TPC, novel representations of the Green's function for a TPC-like geometry were worked out. This analytical approach permits accurate predictions of track distortions due to an arbitrary space charge distribution (by solving the Langevin equation) as well as the possibility to benchmark common numerical methods to calculate such space charge fields. (C) 2011 Elsevier B.V. All rights reserved.
Space-charge impedance calculations in long-wavelength approximation
Kurennoy, Sergey S.
1999-12-01
Space-charge impedance calculations for smooth vacuum chambers with an arbitrary cross-section and perfectly conducting walls are considered in the long-wavelength approximation, when ωb/(βγc)≪1, where b is a typical transverse size. For the SNS beam energies βγ⩽1.8, and the wavelengths are long when λ≫b. Within the long-wavelength approximation, the fields can be found by solving a 2-D electrostatic problem. Two examples are presented: the space-charge impedance of screening wires (RF-cage) and of a ceramic chamber with inner metal stripes. In addition, we explore the transverse space-charge impedance of a circular pipe with account of betatron oscillations in a wide frequency range.
ACHROMAT WITH LINEAR SPACE CHARGE FOR BUNCHED BEAMS
Energy Technology Data Exchange (ETDEWEB)
RAPARIA,D.; ALESSI,J.G.; LEE,Y.Y.; WENG,W.T.
1998-08-23
The standard definition for an achromat is a transport line having zero values for the spatial dispersion (R16) and the angular dispersion (RZ6). For a bunched beam with linear space charge this definition of achromaticity does not hold. The linear space charge in the presence of a bend provides coupling between (a) bunch spatial width and bunch length (R1.5) and (b) bunch angular spread and bunch length (R25). Therefore, achromaticity should be redefined as a line having zero values of the spatial dispersion (R16), the angular dispersion (R26), and matrix elements R15 and R25. These additional conditions (R15=R25=0) can be achieved, for example, with two small RF cavities at appropriate locations in the achromat, to cancel space charge effects. An example of the application of this technique to the Spallation Neutron Source (SNS) high energy beam transport line is presented.
Compensating tune spread induced by space charge in bunched beams
Energy Technology Data Exchange (ETDEWEB)
Litvinenko, V.; Wang, G.
2015-05-03
The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.
Compensating tune spread induced by space charge in bunched beams
Energy Technology Data Exchange (ETDEWEB)
Litvinenko, V.; Wang, G.
2015-05-03
The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.
Space-Charge Experiments at the CERN Proton Synchrotron
Franchetti, Giuliano; Hofmann, I; Martini, M; Métral, E; Qiang, J; Ryne, D; Steerenberg, R; CFA Beam Dynamics Workshop “High Intensity and Brightness Hadron Beams”
2005-01-01
Benchmarking of the simulation codes used for the design of the next generation of high beam power accelerators is of paramount importance due to the very demanding requirements on the level of beam losses. This is usually accomplished by comparing simulation results against available theories, and more importantly, against experimental observations. To this aim, a number of well-defined test cases, obtained by accurate measurements made in existing machines, are of great interest. Such measurements have been made in the CERN Proton Synchrotron to probe three space-charge effects: (i) transverse emittance blow-up due to space-charge induced crossing of the integer or half-integer stop-band, (ii) space-charge and octupole driven resonance trapping, and (iii) intensity-dependent emittance transfer between the two transverse planes. The last mechanism is discussed in detail in this paper and compared to simulation predictions.
Charging of space debris in the LEO and GEO regions
Sen, Abhijit; Tiwari, Sanat Kumar
The near exponential rise of space debris at the satellite orbital altitudes (particularly in the low earth orbit (LEO) region) and the risk they pose for space assets is a source of major concern for all nations engaged in space activities. Considerable efforts are therefore being expended into accurate modeling and tracking of these objects and various ideas for the safe removal of these debris are being explored. The debris objects are likely to acquire a large amount of charge since they are typically found in a plasma environment - such as the earth’s ionospheric plasma in the LEO region (100 kms to 1000 kms) and the radiation belts in the geosynchronous orbit (GEO) region. The consequent flow of electron and ion currents on them lead to the accumulation of a large amount of surface charge and the development of a surface potential on these objects. The influence of the plasma environment on the dynamics and charging of the debris is a relatively unexplored area of Space Situational Awareness (SSA) and Space Debris (SD) research and can be potentially important for the accurate prediction of the long-term evolution of debris orbits and their collision probabilities with other space objects. In this paper we will report on the charging of space debris under a variety of orbital conditions in the LEO and GEO regions using both analytic and particle-in-cell (PIC) modeling. The analytic estimates are obtained using refined Orbit Motion Limited (OML) modeling while the simulation studies are carried out using the SPIS code [1]. In the GEO region account is taken of charging due to photoemission processes as well as energetic beam charging. The PIC approach enables us to study charging of irregularly shaped debris objects as well as differential charging on objects that are composed of patches of conducting and insulated regions. The dynamical consequences of the debris charging on their orbital trajectories and rotational characteristics will be discussed. [1] J
Nonlinear State Space Modeling and System Identification for Electrohydraulic Control
Directory of Open Access Journals (Sweden)
Jun Yan
2013-01-01
Full Text Available The paper deals with nonlinear modeling and identification of an electrohydraulic control system for improving its tracking performance. We build the nonlinear state space model for analyzing the highly nonlinear system and then develop a Hammerstein-Wiener (H-W model which consists of a static input nonlinear block with two-segment polynomial nonlinearities, a linear time-invariant dynamic block, and a static output nonlinear block with single polynomial nonlinearity to describe it. We simplify the H-W model into a linear-in-parameters structure by using the key term separation principle and then use a modified recursive least square method with iterative estimation of internal variables to identify all the unknown parameters simultaneously. It is found that the proposed H-W model approximates the actual system better than the independent Hammerstein, Wiener, and ARX models. The prediction error of the H-W model is about 13%, 54%, and 58% less than the Hammerstein, Wiener, and ARX models, respectively.
Electron cloud and space charge effects in the Fermilab Booster
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.; /Fermilab
2007-06-01
The stable region of the Fermilab Booster beam in the complex coherent-tune-shift plane appears to have been shifted far away from the origin by its intense space charge making Landau damping appear impossible. Simulations reveal a substantial buildup of electron cloud in the whole Booster ramping cycle, both inside the unshielded combined-function magnets and the beam pipes joining the magnets, whenever the secondary-emission yield (SEY) is larger than {approx}1.6. The implication of the electron-cloud effects on the space charge and collective instabilities of the beam is investigated.
Effects of Longitudinal Space Charge Wake at PAL-XFEL
Kim, E S; Huang, J Y; Park, S J
2005-01-01
Longitudinal space charge wake is an important source that can generate microbunching instability at accelerator systems for X-ray free-electron laser. We present investigation to minimize gain of energy modulation due to the longitudinal space charge wakes that are caused at RF photocathode gun, two bunch compressors and linac at the PAL-XFEL, which include optimization of parameters for two bunch compressors and consideration of a laser heater. These studies are performd by using integral equation and numerical simulation methods. Design studies of a system for the laser heater are presented. We also show simulation results on effects of interaction between electron beam and laser.
Nonlinear Multigrid solver exploiting AMGe Coarse Spaces with Approximation Properties
DEFF Research Database (Denmark)
Christensen, Max la Cour; Villa, Umberto; Engsig-Karup, Allan Peter;
The paper introduces a nonlinear multigrid solver for mixed finite element discretizations based on the Full Approximation Scheme (FAS) and element-based Algebraic Multigrid (AMGe). The main motivation to use FAS for unstructured problems is the guaranteed approximation property of the AMGe coarse...... spaces that were developed recently at Lawrence Livermore National Laboratory. These give the ability to derive stable and accurate coarse nonlinear discretization problems. The previous attempts (including ones with the original AMGe method), were less successful due to lack of such good approximation...... are compared to FAS on a nonlinear saddle point problem with applications to porous media flow. It is demonstrated that FAS is faster than Newton’s method and Picard iterations for the experiments considered here. Due to the guaranteed approximation properties of our AMGe, the coarse spaces are very accurate...
Analytical Charge Voltage Model in MOS Inversion Layer Based on Space Charge Capacitance
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC,continuous expressions of surface potential and inversion layer carrier density are derived.Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.
Magnetic charge lattices, moduli spaces and fusion rules
Energy Technology Data Exchange (ETDEWEB)
Kampmeijer, L. [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)], E-mail: leo.kampmeijer@uva.nl; Slingerland, J.K. [Dublin Institute for Advanced Studies, School for Theoretical Physics, 10 Burlington Rd, Dublin (Ireland)], E-mail: slingerland@stp.dias.ie; Schroers, B.J. [Department of Mathematics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS (United Kingdom)], E-mail: bernd@ma.hw.ac.uk; Bais, F.A. [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)], E-mail: bais@science.uva.nl
2009-01-01
We analyze the labelling and fusion properties of magnetic charge sectors consisting of smooth BPS monopoles in Yang-Mills-Higgs theory with arbitrary gauge group G spontaneously broken to a subgroup H. The magnetic charges are restricted by a generalized Dirac quantization condition and by an inequality due to Murray. Geometrically, the set of allowed charges is a solid cone in the coroot lattice of G, which we call the Murray cone. We argue that magnetic charge sectors correspond to points in this cone divided by the Weyl group of H so that magnetic charge sectors are labelled by dominant integral weights of the dual group H*. We define generators of the Murray cone modulo Weyl group, and interpret the monopoles in the associated magnetic charge sectors as basic; monopoles in sectors with decomposable charges are interpreted as composite configurations. This interpretation is supported by the dimensionality of the moduli spaces associated to the magnetic charges and by classical fusion properties for smooth monopoles in particular cases. Throughout the paper we compare our findings with corresponding results for singular monopoles recently obtained by Kapustin and Witten.
A nonlinear feedback model for granular and surface charging
Shinbrot, Troy; Kozachkov, Leo; Siu, Theo
2015-03-01
Independent laboratories have experimentally demonstrated that identical materials brought into symmetric contact generate contact charges. Even the most basic features of this odd behavior remain to be explained. In this talk, we provide a simple, Ising-like, model that appears to account for many of the observed phenomena. We calculate the electric field acting on surface molecules in a lattice, and we show that if the molecules are polarizable, then infinitesimal random polarizations typically build exponentially rapidly in time. These polarizations self-assemble to produce surface patterns that come in two types, and we find that one of these types accounts for strong localized charging, while the other produces a weaker persistent surface charge pattern. We summarize predictions for both ideal surfaces and for defects in granular beds. This work was supported by NSF Grant DMR-1404792.
Space Charge MitigationWith Longitudinally Hollow Bunches
Oeftiger, Adrian; Rumolo, Giovanni; CERN. Geneva. ATS Department
2016-01-01
Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.
Simulation and observation of driven beam oscillations with space charge in the CERN PS Booster
McAteer, M; Benedetto, E; Carli, C; Findlay, A; Mikulec, B; Tomás, R
2014-01-01
As part of the LHC Injector Upgrade project, the CERN PS Booster will be required to operate at nearly doubled intensity with little allowable increase in emittance growth or beam loss. A campaign of nonlinear optics measurements from turn-by-turn trajectory measurements, with the goal of characterizing and then compensating for higher-order resonances, is planned for after Long Shutdown 1. The trajectory measurement system is expected initially to require high intensity beam in order to have good position measurement resolution, so understanding space charge effects will be important for optics analysis. We present the results of simulations of driven beam oscillations with space charge effects, and comparison with trial beam trajectory measurements.
Nonlinear screening of charges induced in graphene by metal contacts
Khomyakov, Petr; Starikov, A.A.; Brocks, G.; Kelly, Paul J.
2010-01-01
To understand the band bending caused by metal contacts, we study the potential and charge density induced in graphene in response to contact with a metal strip. We find that the screening is weak by comparison with a normal metal as a consequence of the ultrarelativistic nature of the electron
Non-Linearity in Wide Dynamic Range CMOS Image Sensors Utilizing a Partial Charge Transfer Technique
Directory of Open Access Journals (Sweden)
Izhal Abdul Halin
2009-11-01
Full Text Available The partial charge transfer technique can expand the dynamic range of a CMOS image sensor by synthesizing two types of signal, namely the long and short accumulation time signals. However the short accumulation time signal obtained from partial transfer operation suffers of non-linearity with respect to the incident light. In this paper, an analysis of the non-linearity in partial charge transfer technique has been carried, and the relationship between dynamic range and the non-linearity is studied. The results show that the non-linearity is caused by two factors, namely the current diffusion, which has an exponential relation with the potential barrier, and the initial condition of photodiodes in which it shows that the error in the high illumination region increases as the ratio of the long to the short accumulation time raises. Moreover, the increment of the saturation level of photodiodes also increases the error in the high illumination region.
Non-Linearity in Wide Dynamic Range CMOS Image Sensors Utilizing a Partial Charge Transfer Technique
Shafie, Suhaidi; Kawahito, Shoji; Halin, Izhal Abdul; Hasan, Wan Zuha Wan
2009-01-01
The partial charge transfer technique can expand the dynamic range of a CMOS image sensor by synthesizing two types of signal, namely the long and short accumulation time signals. However the short accumulation time signal obtained from partial transfer operation suffers of non-linearity with respect to the incident light. In this paper, an analysis of the non-linearity in partial charge transfer technique has been carried, and the relationship between dynamic range and the non-linearity is studied. The results show that the non-linearity is caused by two factors, namely the current diffusion, which has an exponential relation with the potential barrier, and the initial condition of photodiodes in which it shows that the error in the high illumination region increases as the ratio of the long to the short accumulation time raises. Moreover, the increment of the saturation level of photodiodes also increases the error in the high illumination region. PMID:22303133
Space Charge Dominated Beams in the Iucf Cooler
Nagaitsev, Sergei
1995-01-01
Many present and future accelerator projects require significantly increased brightness of the accelerated and stored beams to make modern nuclear and high energy experiments feasible. In the case of IUCF Cooler it has been stated that there is strong motivation for increased beam intensity to provide the designed luminosity for the future Light Ion Spin Synchrotron. To achieve the desired brightness of the beam one must consider a complex problem involving both effective injection and circumventing various intensity limits. This dissertation is essentially a collection of theoretical models and experimental observations which, taken together, make an attempt to analyze numerous intensity and space charge related effects in the IUCF Cooler. We found that the proton beams in the IUCF Cooler are nearly completely space charge dominated longitudinally. This leads to a number of beam properties, such as coherent synchrotron frequency shift and an absence of decoherence in the synchrotron phase oscillations, which have not been observed before. We observed experimentally that the intensity limit in the IUCF Cooler is a peak current limit due to space charge effects. Beam losses occur due to incoherent transverse effects, such as large space charge tune shift and the formation of tails. In addition to that, a very precise bunched beam current monitor was invented and tested. This device could be used in the future precise nuclear experiments.
Quantum electrodynamics with arbitrary charge on a noncommutative space
Institute of Scientific and Technical Information of China (English)
ZHOU Wan-Ping; CAI Shao-Hong; LONG Zheng-Wen
2009-01-01
Using the Seiberg-Witten map,we obtain a quantum electrodynamics on a noncommutative space,which has arbitrary charge and keep the gauge invariance to at the leading order in theta.The one-loop divergence and Compton scattering are reinvestigated.The uoncommutative effects are larger than those in ordinary noncommutative quantum electrodynamics.
On space enrichment estimator for nonlinear Poisson-Boltzmann
Randrianarivony, Maharavo
2013-10-01
We consider the mathematical aspect of the nonlinear Poisson-Boltzmann equation which physically governs the ionic interaction between solute and solvent media. The presented a-posteriori estimates can be computed locally in a very efficient manner. The a-posteriori error is based upon hierarchical space enrichment which ensures its efficiency and reliability. A brief survey of the solving of the nonlinear system resulting from the FEM discretization is reported. To corroborate the analysis, we report on a few numerical results for illustrations. We numerically examine some values of the constants encountered in the theoretical study.
Avetissian, Hamlet
2006-01-01
This book covers a large class of fundamental investigations into Relativistic Nonlinear Electrodynamics. It explores the interaction between charged particles and strong laser fields, mainly concentrating on contemporary problems of x-ray lasers, new type small set-up high-energy accelerators of charged particles, as well as electron-positron pair production from super powerful laser fields of relativistic intensities. It will also discuss nonlinear phenomena of threshold nature that eliminate the concurrent inverse processes in the problems of Laser Accelerator and Free Electron Laser, thus creating new opportunities for solving these problems.
Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes
Biesheuvel, P M
2009-01-01
The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory in the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes wi...
Electromagnetic radiation from linearly and nonlinearly oscillating charge drops
Grigor'ev, A. I.; Shiryaeva, S. O.
2016-12-01
It has been shown that analytic calculations of the intensity of electromagnetic radiation from an oscillating charged drop in the approximation linear in the oscillation amplitude (small parameter is on the order of 0.1) give only the quadrupole component of the total radiation. The dipole component can only be obtained in calculations using higher-order approximations. Nevertheless, the intensity of the dipole radiation turns out to be substantially higher (by 14-15 orders of magnitude). This is because the decomposition of radiation from a system of charges into multipole components (differing even in the rates of decrease in the potential with the distance) is carried out using the expansion in a substantially smaller parameter, viz., the ratio of the size of the emitting system (in our case, a drop of radius 10 μm) to the distance to the point of observation in the wave zone of the emission of radiation (emitted wavelength) of 100-1000 m. As a result, this second small parameter is on the order of 10-7 to 10-8. On the other hand, in accordance with the field theory, the ratio of intensities of quadrupole and dipole radiations is proportional to the squared ratio of the hydrodynamic velocity of the oscillating surface of a charged drop to the velocity of propagation of an electromagnetic signal in vacuum (velocity of light), which yields a ratio of 10-14 to 10-15.
Kerasidou, A. P.; Khammar, F.; Iliopoulos, K.; Ayadi, A.; El-Ghayoury, A.; Zouari, N.; Mhiri, T.; Sahraoui, B.
2014-03-01
The third order nonlinearities of two azobenzene-iminopyridine molecular systems have been investigated employing the Z-scan technique at 532 nm, 30 ps. The objective of the work has been to study and to compare the nonlinearity of two iminopyridine based ligands substituted with one (NO2AzoIminoPy, A) and two azobenzene units ((NO2Azo)2IminoPy, B). The ligand B exhibits an extended conjugated structure and higher charge transfer within the molecule. Our results show high dependence of the nonlinearity on both the conjugation length within the molecule and on the number of the electron accepting units.
A nonlinear state-space approach to hysteresis identification
Noël, J. P.; Esfahani, A. F.; Kerschen, G.; Schoukens, J.
2017-02-01
Most studies tackling hysteresis identification in the technical literature follow white-box approaches, i.e. they rely on the assumption that measured data obey a specific hysteretic model. Such an assumption may be a hard requirement to handle in real applications, since hysteresis is a highly individualistic nonlinear behaviour. The present paper adopts a black-box approach based on nonlinear state-space models to identify hysteresis dynamics. This approach is shown to provide a general framework to hysteresis identification, featuring flexibility and parsimony of representation. Nonlinear model terms are constructed as a multivariate polynomial in the state variables, and parameter estimation is performed by minimising weighted least-squares cost functions. Technical issues, including the selection of the model order and the polynomial degree, are discussed, and model validation is achieved in both broadband and sine conditions. The study is carried out numerically by exploiting synthetic data generated via the Bouc-Wen equations.
Generalized non-linear strength theory and transformed stress space
Institute of Scientific and Technical Information of China (English)
YAO Yangping; LU Dechun; ZHOU Annan; ZOU Bo
2004-01-01
Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula, and it includes almost all the present non-linear strength theories, which can be used in just one material. The shape of failure function of the GNST is a smooth curve between the SMP criterion and the Mises criterion on the π-plane, and an exponential curve on the meridian plane. Through the transformed stress space based on the GNST, the combination of the GNST and various constitutive models using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state.
Galerkin approximations of nonlinear optimal control problems in Hilbert spaces
Directory of Open Access Journals (Sweden)
Mickael D. Chekroun
2017-07-01
Full Text Available Nonlinear optimal control problems in Hilbert spaces are considered for which we derive approximation theorems for Galerkin approximations. Approximation theorems are available in the literature. The originality of our approach relies on the identification of a set of natural assumptions that allows us to deal with a broad class of nonlinear evolution equations and cost functionals for which we derive convergence of the value functions associated with the optimal control problem of the Galerkin approximations. This convergence result holds for a broad class of nonlinear control strategies as well. In particular, we show that the framework applies to the optimal control of semilinear heat equations posed on a general compact manifold without boundary. The framework is then shown to apply to geoengineering and mitigation of greenhouse gas emissions formulated here in terms of optimal control of energy balance climate models posed on the sphere $\\mathbb{S}^2$.
NONLINEAR MULTIGRID SOLVER EXPLOITING AMGe COARSE SPACES WITH APPROXIMATION PROPERTIES
Energy Technology Data Exchange (ETDEWEB)
Christensen, Max La Cour [Technical Univ. of Denmark, Lyngby (Denmark); Villa, Umberto E. [Univ. of Texas, Austin, TX (United States); Engsig-Karup, Allan P. [Technical Univ. of Denmark, Lyngby (Denmark); Vassilevski, Panayot S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-01-22
The paper introduces a nonlinear multigrid solver for mixed nite element discretizations based on the Full Approximation Scheme (FAS) and element-based Algebraic Multigrid (AMGe). The main motivation to use FAS for unstruc- tured problems is the guaranteed approximation property of the AMGe coarse spaces that were developed recently at Lawrence Livermore National Laboratory. These give the ability to derive stable and accurate coarse nonlinear discretization problems. The previous attempts (including ones with the original AMGe method, [5, 11]), were less successful due to lack of such good approximation properties of the coarse spaces. With coarse spaces with approximation properties, our FAS approach on un- structured meshes should be as powerful/successful as FAS on geometrically re ned meshes. For comparison, Newton's method and Picard iterations with an inner state-of-the-art linear solver is compared to FAS on a nonlinear saddle point problem with applications to porous media ow. It is demonstrated that FAS is faster than Newton's method and Picard iterations for the experiments considered here. Due to the guaranteed approximation properties of our AMGe, the coarse spaces are very accurate, providing a solver with the potential for mesh-independent convergence on general unstructured meshes.
Discrete state space modeling and control of nonlinear unknown systems.
Savran, Aydogan
2013-11-01
A novel procedure for integrating neural networks (NNs) with conventional techniques is proposed to design industrial modeling and control systems for nonlinear unknown systems. In the proposed approach, a new recurrent NN with a special architecture is constructed to obtain discrete-time state-space representations of nonlinear dynamical systems. It is referred as the discrete state-space neural network (DSSNN). In the DSSNN, the outputs of the hidden layer neurons of the DSSNN represent the system's (pseudo) state. The inputs are fed to output neurons and the delayed outputs of the hidden layer neurons are fed to their inputs via adjustable weights. The discrete state space model of the actual system is directly obtained by training the DSSNN with the input-output data. A training procedure based on the back-propagation through time (BPTT) algorithm is developed. The Levenberg-Marquardt (LM) method with a trust region approach is used to update the DSSNN weights. Linear state space models enable to use well developed conventional analysis and design techniques. Thus, building a linear model of a system has primary importance in industrial applications. Thus, a suitable linearization procedure is proposed to derive the linear state space model from the nonlinear DSSNN representation. The controllability, observability and stability properties are examined. The state feedback controllers are designed with both the linear quadratic regulator (LQR) and the pole placement techniques. The regulator and servo control problems are both addressed. A full order observer is also designed to estimate the state variables. The performance of the proposed procedure is demonstrated by applying for both single-input single-output (SISO) and multiple-input multiple-output (MIMO) nonlinear control problems. © 2013 ISA. Published by Elsevier Ltd. All rights reserved.
Space charge relaxation in polyetherimides by the electric modulus formalism
Mudarra, M.; Belana, J.; Cañadas, J. C.; Diego, J. A.; Sellarès, J.; Díaz-Calleja, R.; Sanchís, M. J.
2000-10-01
Dynamic electrical analysis shows that at high temperatures (above the glass transition temperature), the electrical properties of polyetherimide are strongly influenced by space charge. In this article we have studied the relaxation of space charge in two commercial varieties of polyetherimide: Ultem 1000 and Ultem 5000. Their conductive properties were determined by dynamic electrical analysis, using the electric modulus formalism. The complex part of the electric modulus was fitted to Coelho's model which considers ohmic conductivity and diffusion as the prevailing charge transport mechanisms. The complex part of the electric modulus exhibits a peak in the low frequency range that can be associated with space charge. A good agreement between experimental and calculated data is observed after the fitting process to Coelho's model. Differences in the electrode behavior were required: blocking electrode conditions in the case of Ultem 5000 and partially blocking electrode for Ultem 1000. In both cases the conductivity determined is thermally activated and it increases with the temperature due to an increasing mobility, as their carrier densities do not vary significantly in the temperature range studied.
Discrete space charge affected field emission: Flat and hemisphere emitters
Energy Technology Data Exchange (ETDEWEB)
Jensen, Kevin L., E-mail: kevin.jensen@nrl.navy.mil [Code 6854, Naval Research Laboratory, Washington, DC 20375 (United States); Shiffler, Donald A.; Tang, Wilkin [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States); Rittersdorf, Ian M. [Code 6770, Naval Research Laboratory, Washington, DC 20375 (United States); Lebowitz, Joel L. [Department of Mathematics and Department of Physics, Rutgers University, Piscataway, New Jersey 08854-8019 (United States); Harris, John R. [U.S. Navy Reserve, New Orleans, Louisiana 70143 (United States); Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Petillo, John J. [Leidos, Billerica, Massachusetts 01821 (United States); Luginsland, John W. [Physics and Electronics Directorate, AFOSR, Arlington, Virginia 22203 (United States)
2015-05-21
Models of space-charge affected thermal-field emission from protrusions, able to incorporate the effects of both surface roughness and elongated field emitter structures in beam optics codes, are desirable but difficult. The models proposed here treat the meso-scale diode region separate from the micro-scale regions characteristic of the emission sites. The consequences of discrete emission events are given for both one-dimensional (sheets of charge) and three dimensional (rings of charge) models: in the former, results converge to steady state conditions found by theory (e.g., Rokhlenko et al. [J. Appl. Phys. 107, 014904 (2010)]) but show oscillatory structure as they do. Surface roughness or geometric features are handled using a ring of charge model, from which the image charges are found and used to modify the apex field and emitted current. The roughness model is shown to have additional constraints related to the discrete nature of electron charge. The ability of a unit cell model to treat field emitter structures and incorporate surface roughness effects inside a beam optics code is assessed.
Geometrically Nonlinear Finite Element Analysis of a Composite Space Reflector
Lee, Kee-Joo; Leet, Sung W.; Clark, Greg; Broduer, Steve (Technical Monitor)
2001-01-01
Lightweight aerospace structures, such as low areal density composite space reflectors, are highly flexible and may undergo large deflection under applied loading, especially during the launch phase. Accordingly, geometrically nonlinear analysis that takes into account the effect of finite rotation may be needed to determine the deformed shape for a clearance check and the stress and strain state to ensure structural integrity. In this study, deformation of the space reflector is determined under static conditions using a geometrically nonlinear solid shell finite element model. For the solid shell element formulation, the kinematics of deformation is described by six variables that are purely vector components. Because rotational angles are not used, this approach is free of the limitations of small angle increments. This also allows easy connections between substructures and large load increments with respect to the conventional shell formulation using rotational parameters. Geometrically nonlinear analyses were carried out for three cases of static point loads applied at selected points. A chart shows results for a case when the load is applied at the center point of the reflector dish. The computed results capture the nonlinear behavior of the composite reflector as the applied load increases. Also, they are in good agreement with the data obtained by experiments.
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
Hendi, S H; Panah, B Eslam; Momennia, M
2015-01-01
Motivated by the violation of Lorentz invariancy in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered with an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally we investigate thermal stability conditions for these black hole solutions in context of canonical ensemble. We show that although there is not physical small black hole, large black holes are physical and enjoy thermal stability in gravity's rainbow.
Space vehicle pose estimation via optical correlation and nonlinear estimation
Rakoczy, John M.; Herren, Kenneth A.
2008-03-01
A technique for 6-degree-of-freedom (6DOF) pose estimation of space vehicles is being developed. This technique draws upon recent developments in implementing optical correlation measurements in a nonlinear estimator, which relates the optical correlation measurements to the pose states (orientation and position). For the optical correlator, the use of both conjugate filters and binary, phase-only filters in the design of synthetic discriminant function (SDF) filters is explored. A static neural network is trained a priori and used as the nonlinear estimator. New commercial animation and image rendering software is exploited to design the SDF filters and to generate a large filter set with which to train the neural network. The technique is applied to pose estimation for rendezvous and docking of free-flying spacecraft and to terrestrial surface mobility systems for NASA's Vision for Space Exploration. Quantitative pose estimation performance will be reported. Advantages and disadvantages of the implementation of this technique are discussed.
What is the "best" atomic charge model to describe through-space charge-transfer excitations?
Jacquemin, Denis; Le Bahers, Tangui; Adamo, Carlo; Ciofini, Ilaria
2012-04-28
We investigate the efficiency of several partial atomic charge models (Mulliken, Hirshfeld, Bader, Natural, Merz-Kollman and ChelpG) for investigating the through-space charge-transfer in push-pull organic compounds with Time-Dependent Density Functional Theory approaches. The results of these models are compared to benchmark values obtained by determining the difference of total densities between the ground and excited states. Both model push-pull oligomers and two classes of "real-life" organic dyes (indoline and diketopyrrolopyrrole) used as sensitisers in solar cell applications have been considered. Though the difference of dipole moments between the ground and excited states is reproduced by most approaches, no atomic charge model is fully satisfactory for reproducing the distance and amount of charge transferred that are provided by the density picture. Overall, the partitioning schemes fitting the electrostatic potential (e.g. Merz-Kollman) stand as the most consistent compromises in the framework of simulating through-space charge-transfer, whereas the other models tend to yield qualitatively inconsistent values.
Nonlinear Sigma Models with Compact Hyperbolic Target Spaces
Gubser, Steven; Schoenholz, Samuel S; Stoica, Bogdan; Stokes, James
2015-01-01
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the $O(2)$ model. Unlike in the $O(2)$ case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggest...
Principal Manifolds and Nonlinear Dimensionality Reduction via Tangent Space Alignment
Institute of Scientific and Technical Information of China (English)
张振跃; 查宏远
2004-01-01
We present a new algorithm for manifold learning and nonlinear dimensionality reduction. Based on a set of unorganized da-ta points sampled with noise from a parameterized manifold, the local geometry of the manifold is learned by constructing an approxi-mation for the tangent space at each point, and those tangent spaces are then aligned to give the global coordinates of the data pointswith respect to the underlying manifold. We also present an error analysis of our algorithm showing that reconstruction errors can bequite small in some cases. We illustrate our algorithm using curves and surfaces both in 2D/3D Euclidean spaces and higher dimension-al Euclidean spaces. We also address several theoretical and algorithmic issues for further research and improvements.
On nonlinear stability in various random normed spaces
Directory of Open Access Journals (Sweden)
Saadati Reza
2011-01-01
Full Text Available Abstract In this article, we prove the nonlinear stability of the quartic functional equation 1 6 f ( x + 4 y + f ( 4 x - y = 3 0 6 9 f x + y 3 + f ( x + 2 y (1 + 1 3 6 f ( x - y - 1 3 9 4 f ( x + y + 4 2 5 f ( y - 1 5 3 0 f ( x (2 (3 in the setting of random normed spaces Furthermore, the interdisciplinary relation among the theory of random spaces, the theory of non-Archimedean space, the theory of fixed point theory, the theory of intuitionistic spaces and the theory of functional equations are also presented in the article.
Incoherent effect of space charge and electron cloud
Franchetti, G.; Hofmann, I.; Fischer, W.; Zimmermann, F.
2009-12-01
Trapping by resonances or scattering off resonances induced by space charge (SC) or electron cloud (EC) in conjunction with synchrotron motion can explain observations of slow beam loss and emittance growth, which are often accompanied by changes in the longitudinal beam profile. In this paper we review the recent progress in understanding and modeling of the underlying mechanisms, highlight the differences and similarities between space charge and electron cloud, and discuss simulation results in the light of experimental observations, e.g., at GSI, CERN, and BNL. In particular, we address the role of the pinched electrons and describe in detail the complexity of the electron pinch formation. We present simulation results within a dipole or in a field-free region of the beam pipe, which reveal the morphology and main features of this phenomenon, explain the physical origin of the complex electron structures like stripe in either field configuration, and discuss the dependence on some key parameters.
Incoherent Effect of Space Charge and Electron Cloud
Franchetti, G; Fischer, W; Zimmermann, F
2009-01-01
Trapping by resonances or scattering off resonances induced by space charge (SC) or electron cloud (EC) in conjunction with synchrotron motion can explain observations of slow beam loss and emittance growth, which are often accompanied by changes in the longitudinal beam profile. In this paper we review the recent progress in understanding and modeling of the underlying mechanisms, highlight the differences and similarities between space charge and electron cloud, and discuss simulation results in the light of experimental observations, e.g., at GSI, CERN, and BNL. In particular, we address the role of the pinched electrons and describe in detail the complexity of the electron pinch formation. We present simulation results within a dipole or in a field-free region of the beam pipe, which reveal the morphology and main features of this phenomenon, explain the physical origin of the complex electron structures like stripe in either field configuration, and discuss the dependence on some key parameters.
Space charge distribution measurement methods and particle loaded insulating materials
Energy Technology Data Exchange (ETDEWEB)
Hole, S [Laboratoire des Instruments et Systemes d' Ile de France, Universite Pierre et Marie Curie-Paris6, 10 rue Vauquelin, 75005 Paris (France); Sylvestre, A [Laboratoire d' Electrostatique et des Materiaux Dielectriques, CNRS UMR5517, 25 avenue des Martyrs, BP 166, 38042 Grenoble cedex 9 (France); Lavallee, O Gallot [Laboratoire d' Etude Aerodynamiques, CNRS UMR6609, boulevard Marie et Pierre Curie, Teleport 2, BP 30179, 86962 Futuroscope, Chasseneuil (France); Guillermin, C [Schneider Electric Industries SAS, 22 rue Henry Tarze, 38000 Grenoble (France); Rain, P [Laboratoire d' Electrostatique et des Materiaux Dielectriques, CNRS UMR5517, 25 avenue des Martyrs, BP 166, 38042 Grenoble cedex 9 (France); Rowe, S [Schneider Electric Industries SAS, 22 rue Henry Tarze, 38000 Grenoble (France)
2006-03-07
In this paper the authors discuss the effects of particles (fillers) mixed in a composite polymer on the space charge measurement techniques. The origin of particle-induced spurious signals is determined and silica filled epoxy resin is analysed using the laser-induced-pressure-pulse (LIPP) method, the pulsed-electro-acoustic (PEA) method and the laser-induced-thermal-pulse (LITP) method. A spurious signal identified as the consequence of a piezoelectric effect of some silica particles is visible for all the method. Moreover, space charges are clearly detected at the epoxy/silica interface after a 10 kV mm{sup -1} poling at room temperature for 2 h.
The influence of filler particles on space charge measurements
Energy Technology Data Exchange (ETDEWEB)
Hole, Stephane [Laboratoire des Instruments et Systemes d' Ile de France, Universite Pierre et Marie Curie - 10, rue Vauquelin, 75005 Paris, France (France); Sylvestre, Alain [Laboratoire d' lectrostatique et des Materiaux Dielectriques, CNRS UMR5517 - 25, avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Rowe, Stephen [Direction des Recherches Materiaux, Schneider Electric SA - 20, rue Henri Tarze, 38050 Grenoble Cedex (France)
2004-07-07
The effects of filler particles on the signal measured using the pressure-wave-propagation method to determine the space charge distribution are analysed. A special test sample geometry is used to classify the influence of particles, and in particular, the role of piezoelectricity is discussed. Applications with Epoxy resin samples loaded either by silica or alumina particles are presented. Silica particles are shown to exhibit piezoelectricity which strongly modifies the measured signals.
Emittance coupling driven by space charge in the CSNS linac
Institute of Scientific and Technical Information of China (English)
YIN Xue-Jun; FU Shi-Nian; PENG Jun
2009-01-01
In the conventional design of RF linacs, the bunched beams are not in thermal equilibrium. The space charge forces couple the particle motions between the transverse and the longitudinal directions. Fur-thermore it will cause the equipartitioning process which leads to emittance growth and halo formation. In the design of the China Spallation Neutron Source (CSNS) linac, three cases are investigated using the Hofmann stability charts. In this paper, we present the equipartitioning beam study of the CSNS Alvarez DTL linac.
Space charge and octupole driven resonance trapping observed at the CERN proton synchrotron
Franchetti, Giuliano; Giovannozzi, Massimo; Martini, Michel; Métral, Elias
2003-01-01
The combined effect of space charge and nonlinear resonance on beam loss and emittance was measured in a benchmarking experiment over a 1.2 s long flat bottom at 1.4 GeV kinetic energy in the presence of a single controllable octupole. By lowering the working point towards the resonance, a gradual transition from a loss-free core emittance blowup to a regime dominated by continuous loss was found. We compare the observation with 3D simulations based on a new analytical space charge model and obtain good agreement in the emittance blowup regime. Our explanation is in terms of the synchrotron oscillation, which causes a periodic tune modulation due to space charge, and leads to trapping and detrapping on the resonance islands. For working points very close to the resonance this induces a beam halo with large radius. The underlying dynamics is studied in detail, and it is claimed that the predicted halo in conjunction with a reduced dynamic aperture for the real machine lattice is the source of the loss observed...
Transverse Space-Charge Effects in Circular Accelerators
Energy Technology Data Exchange (ETDEWEB)
Sacherer, Frank James
1968-10-30
The particles in an accelerator interact with one another by electromagnetic forces and are held together by external focusing forces. Such a many-body system has a large number of transverse modes of oscillation (plasma oscillations) that can be excited at characteristic frequencies by errors in the external guide field. In Part I we examine one mode of oscillation in detail, namely the quadrupole mode that is excited in uniformly charged beams by gradient errors. We derive self-consistent equations of motion for the beam envelope and solve these equations for the case in which the space-charge force is much less than the external focusing force, i.e., for strong-focusing synchrotrons. We find that the resonance intensity is shifted from the value predicted by the usual transverse incoherent space-charge limit; moreover, because the space-charge force depends on the shape and size of the beam, the beam growth in always limited. For gradient errors of the magnitude normally present in strong-focusing synchrotrons, the increase in beam size is small provided the beam parameters are properly chosen; otherwise the growth may be large. Thus gradient errors need not impose a limit on the number of particles that can be accelerated. In Part II we examine the other modes of collective oscillation that are excited by machine imperfections. For simplicity we consider only one-dimensional beams that are confined by harmonic potentials, and only small-amplitude oscillations. The linearized Vlasov and Poisson equations are used to find the twofold infinity of normal modes and eigenfrequencies for the stationary distribution that has uniform charge density in real space. In practice, only the low-order modes (the dipole, quadrupole, sextupole, and one or two additional modes) will be serious, and the resonant conditions for these modes are located on a tune diagram. These results, which are valid for all beam intensities, are compared with the known eigenfrequencies for the
A Method to Overcome Space Charge at Injection
Energy Technology Data Exchange (ETDEWEB)
Ya. Derbenev
2005-09-29
The transverse space charge forces in a high current, low energy beam can be reduced by mean of a large increase of the beam's transverse sizes while maintaining the beam area in the 4D phase space. This can be achieved by transforming the beam area in phase space of each of two normal 2D transverse (either plane or circular) modes from a spot shape into a narrow ring of a large amplitude, but homogeneous in phase. Such a transformation results from the beam evolution in the island of a dipole resonance when the amplitude width of the island shrinks adiabatically. After stacking (by using stripping foils or cooling) the beam in such a state and accelerating to energies sufficiently high that the space charge becomes insignificant, the beam then can be returned back to a normal spot shape by applying the reverse transformation. An arrangement that can provide such beam gymnastics along a transport line after a linac and before a booster and/or in a ring with circulating beam will be described and numerical estimates will be presented. Other potential applications of the method will be briefly discussed.
On time-space of nonlinear phenomena with Gompertzian dynamics.
Waliszewski, Przemyslaw; Konarski, Jerzy
2005-04-01
This paper describes a universal relationship between time and space for a nonlinear process with Gompertzian dynamics, such as growth. Gompertzian dynamics implicates a coupling between time and space. Those two categories are related to each other through a linear function of their logarithms. Moreover, we demonstrate that the spatial fractal dimension is a function of both scalar time and the temporal fractal dimension. The Gompertz function reflects the equilibrium of regular states, that is, states with dynamics that are predictable for any time-point (e.g., sinusoidal glycolytic oscillations) and chaotic states, that is, states with dynamics that are unpredictable in time, but are characterized by certain regularities (e.g., the existence of strange attractor for any biochemical reaction). We conclude that both this equilibrium and volume of the available complementary Euclidean space determine temporal and spatial expansion of a process with Gompertzian dynamics.
Gabor lens theory. [Focusing by space charge of electron cloud
Energy Technology Data Exchange (ETDEWEB)
Irani, A A
1978-01-01
The principle of using the space charge of an electron cloud to focus ion beams was first proposed by Gabor. Electrons are to be confined radially by means of an axial magnetic field B/sub z/ and axially by means of externally applied electric fields E/sub z/. An ion beam of charge density n/sub i/ much less than n/sub e/, the electron charge density can then be focused by the radial electric field set up by the electron cloud. The case considered here is that of a hollow cylindrical conductor charged to a potential +V with grounded rings on either side to set up the axial E/sub z/ field. A solenoid wound around the central conductor supplies the B/sub z/ field. Theoretical calculations are carried out for n/sub e/ maximum as a function of B/sub z/ due to radial confinement and V due to axial confinement and the focal length of the Gabor Lens is calculated.
String formulation of space charge forces in a deflecting bunch
Talman, Richard
2004-10-01
The force between two moving point charges, because of its inverse square law singularity, cannot be applied directly in the numerical simulation of bunch dynamics; radiative effects make this especially true for short bunches being deflected by magnets. This paper describes a formalism circumventing this restriction in which the basic ingredient is the total force on a point charge comoving with a longitudinally aligned, uniformly charged string. Bunch evolution can then be treated using direct particle-to-particle, intrabeam scattering, with no need for an intermediate, particle-in-cell, step. Electric and magnetic fields do not appear individually in the theory. Since the basic formulas are both exact (in paraxial approximation) and fully relativistic, they are applicable to beams of all particle types and all energies. But the theory is expected to be especially useful for calculating the emittance growth of the ultrashort electron bunches of current interest for energy recovery linacs and free-electron lasers. The theory subsumes coherent synchrotron radiation and centrifugal space charge force. Renormalized, on-axis, longitudinal field components are in excellent agreement with values from Saldin et al. [DESY Report No. DESY-TESLA-FEL-96-14, 1995; Nucl. Instrum. Methods Phys. Res., Sect. ANIMAER0168-9002 417, 158 (1998).10.1016/S0168-9002(98)00623-8
String formulation of space charge forces in a deflecting bunch
Directory of Open Access Journals (Sweden)
Richard Talman
2004-10-01
Full Text Available The force between two moving point charges, because of its inverse square law singularity, cannot be applied directly in the numerical simulation of bunch dynamics; radiative effects make this especially true for short bunches being deflected by magnets. This paper describes a formalism circumventing this restriction in which the basic ingredient is the total force on a point charge comoving with a longitudinally aligned, uniformly charged string. Bunch evolution can then be treated using direct particle-to-particle, intrabeam scattering, with no need for an intermediate, particle-in-cell, step. Electric and magnetic fields do not appear individually in the theory. Since the basic formulas are both exact (in paraxial approximation and fully relativistic, they are applicable to beams of all particle types and all energies. But the theory is expected to be especially useful for calculating the emittance growth of the ultrashort electron bunches of current interest for energy recovery linacs and free-electron lasers. The theory subsumes coherent synchrotron radiation and centrifugal space charge force. Renormalized, on-axis, longitudinal field components are in excellent agreement with values from Saldin et al. [DESY Report No. DESY-TESLA-FEL-96-14, 1995; Nucl. Instrum. Methods Phys. Res., Sect. A 417, 158 (1998.NIMAER0168-900210.1016/S0168-9002(9800623-8
Quasinormal modes of four-dimensional topological nonlinear charged Lifshitz black holes
Energy Technology Data Exchange (ETDEWEB)
Becar, Ramon [Universidad Cato lica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)
2016-02-15
We study scalar perturbations of four- dimensional topological nonlinear charged Lifshitz black holes with spherical and plane transverse sections, and we find numerically the quasinormal modes for scalar fields. Then we study the stability of these black holes under massive and massless scalar field perturbations. We focus our study on the dependence of the dynamical exponent, the nonlinear exponent, the angular momentum, and the mass of the scalar field in the modes. It is found that the modes are overdamped, depending strongly on the dynamical exponent and the angular momentum of the scalar field for a spherical transverse section. In contrast, for plane transverse sections the modes are always overdamped. (orig.)
Relaxation of charge in monolayer graphene: Fast nonlinear diffusion versus Coulomb effects
Kolomeisky, Eugene B.; Straley, Joseph P.
2017-01-01
Pristine monolayer graphene exhibits very poor screening because the density of states vanishes at the Dirac point. As a result, charge relaxation is controlled by the effects of zero-point motion (rather than by the Coulomb interaction) over a wide range of parameters. Combined with the fact that graphene possesses finite intrinsic conductivity, this leads to a regime of relaxation described by a nonlinear diffusion equation with a diffusion coefficient that diverges at zero charge density. Some consequences of this fast diffusion are self-similar superdiffusive regimes of relaxation, the development of a charge depleted region at the interface between electron- and hole-rich regions, and finite extinction times for periodic charge profiles.
3D Simulations of Space Charge Effects in Particle Beams
Energy Technology Data Exchange (ETDEWEB)
Adelmann, A
2002-10-01
For the first time, it is possible to calculate the complicated three-dimensional proton accelerator structures at the Paul Scherrer Institut (PSI). Under consideration are external and self effects, arising from guiding and space-charge forces. This thesis has as its theme the design, implementation and validation of a tracking program for charged particles in accelerator structures. This work form part of the discipline of Computational Science and Engineering (CSE), more specifically in computational accelerator modelling. The physical model is based on the collisionless Vlasov-Maxwell theory, justified by the low density ({approx} 10{sup 9} protons/cm{sup 3}) of the beam and of the residual gas. The probability of large angle scattering between the protons and the residual gas is then sufficiently low, as can be estimated by considering the mean free path and the total distance a particle travels in the accelerator structure. (author)
3D Simulations of Space Charge Effects in Particle Beams
Energy Technology Data Exchange (ETDEWEB)
Adelmann, A
2002-10-01
For the first time, it is possible to calculate the complicated three-dimensional proton accelerator structures at the Paul Scherrer Institut (PSI). Under consideration are external and self effects, arising from guiding and space-charge forces. This thesis has as its theme the design, implementation and validation of a tracking program for charged particles in accelerator structures. This work form part of the discipline of Computational Science and Engineering (CSE), more specifically in computational accelerator modelling. The physical model is based on the collisionless Vlasov-Maxwell theory, justified by the low density ({approx} 10{sup 9} protons/cm{sup 3}) of the beam and of the residual gas. The probability of large angle scattering between the protons and the residual gas is then sufficiently low, as can be estimated by considering the mean free path and the total distance a particle travels in the accelerator structure. (author)
Formation and Distribution of Space-Charge in Cross-Linked Polyethylene
Zhang, Ye-Wen; Li, Ji-Xiao; Zheng, Fei-Hu; Peng, Zong-Ren; Wu, Chang-Shun; Xia, Zhong-Fu
2002-08-01
The formation and distribution of space-charge in a cross-linked polyethylene (XLPE) sample are investigated by means of pressure wave propagation, infrared spectroscopy and electrostatic force microscopy (EFM). The related mechanism of space-charge distribution and the structure of XLPE are discussed. The EFM images show that quite large quantitative space-charges locate at the surface of spherulites.
Magnetically charged regular black hole in a model of nonlinear electrodynamics
Ma, Meng-Sen
2015-01-01
We obtain a magnetically charged regular black hole in general relativity. The source to the Einstein field equations is nonlinear electrodynamic field in a physically reasonable model of nonlinear electrodynamics (NED). "Physically" here means the NED model is constructed on the basis of three conditions: the Maxwell asymptotic in the weak electromagnetic field limit; the presence of vacuum birefringence phenomenon; and satisfying the weak energy condition (WEC). In addition, we analyze the thermodynamic properties of the regular black hole in two ways. According to the usual black hole thermodynamics, we calculate the heat capacity at constant charge, from which we know the smaller black hole is more stable. We also employ the horizon thermodynamics to discuss the thermodynamic quantities, especially the heat capacity at constant pressure.
Thermal stability analysis of nonlinearly charged asymptotic AdS black hole solutions
Dehghani, M.; Hamidi, S. F.
2017-08-01
In this paper, the four-dimensional nonlinearly charged black hole solutions have been considered in the presence of the power Maxwell invariant electrodynamics. Two new classes of anti-de Sitter (AdS) black hole solutions have been introduced according to different amounts of the parameters in the nonlinear theory of electrodynamics. The conserved and thermodynamical quantities of either of the black hole classes have been calculated from geometrical and thermodynamical approaches, separately. It has been shown that the first law of black hole thermodynamics is satisfied for either of the AdS black hole solutions we just obtained. Through the canonical and grand canonical ensemble methods, the black hole thermal stability or phase transitions have been analyzed by considering the heat capacities with the fixed black hole charge and fixed electric potential, respectively. It has been found that the new AdS black holes are stable if some simple conditions are satisfied.
Nonlinear rotordynamics analysis. [Space Shuttle Main Engine turbopumps
Noah, Sherif T.
1991-01-01
Effective analysis tools were developed for predicting the nonlinear rotordynamic behavior of the Space Shuttle Main Engine (SSME) turbopumps under steady and transient operating conditions. Using these methods, preliminary parametric studies were conducted on both generic and actual HPOTP (high pressure oxygen turbopump) models. In particular, a novel modified harmonic balance/alternating Fourier transform (HB/AFT) method was developed and used to conduct a preliminary study of the effects of fluid, bearing and seal forces on the unbalanced response of a multi-disk rotor in the presence of bearing clearances. The method makes it possible to determine periodic, sub-, super-synchronous and chaotic responses of a rotor system. The method also yields information about the stability of the obtained response, thus allowing bifurcation analyses. This provides a more effective capability for predicting the response under transient conditions by searching in proximity of resonance peaks. Preliminary results were also obtained for the nonlinear transient response of an actual HPOTP model using an efficient, newly developed numerical method based on convolution integration. Currently, the HB/AFT is being extended for determining the aperiodic response of nonlinear systems. Initial results show the method to be promising.
Program NAJOCSC and space charge effect simulation in C01
Energy Technology Data Exchange (ETDEWEB)
Tang, J.Y.; Chabert, A.; Baron, E
1999-03-10
During the beam tests of the THI project at GANIL, it was found it difficult to increase the beam power above 2 kW at CSS2 extraction. The space charge effect (abbreviated as S.C. effect) in cyclotrons is suspected to play some role in the phenomenon, especially the longitudinal S.C. one and also the coupling between longitudinal and radial motions. The injector cyclotron C01 is studied, and the role played by the S.C. effect in this cyclotron in the THI case is investigated by a simulation method. (K.A.) 12 refs.
Space charge effects for multipactor in coaxial lines
Energy Technology Data Exchange (ETDEWEB)
Sorolla, E., E-mail: eden.sorolla@xlim.fr [XLIM, UMR 7252, Université de Limoges/CNRS, 123 Av. Albert Thomas, 87060 Limoges (France); Sounas, A.; Mattes, M. [Laboratoire d' Électromagnétisme et d' Acoustique (LEMA), École Polytechnique Fédérale de Lausanne, Station 11, CH-1015 Lausanne (Switzerland)
2015-03-15
Multipactor is a hazardous vacuum discharge produced by secondary electron emission within microwave devices of particle accelerators and telecommunication satellites. This work analyzes the dynamics of the multipactor discharge within a coaxial line for the mono-energetic electron emission model taking into account the space charge effects. The steady-state is predicted by the proposed model and an analytical expression for the maximum number of electrons released by the discharge presented. This could help to link simulations to experiments and define a multipactor onset criterion.
Simulations of space charge neutralization in a magnetized electron cooler
Energy Technology Data Exchange (ETDEWEB)
Gerity, James [Texas A-M; McIntyre, Peter M. [Texas A-M; Bruhwiler, David Leslie [RadiaSoft, Boulder; Hall, Christopher [RadiaSoft, Boulder; Moens, Vince Jan [Ecole Polytechnique, Lausanne; Park, Chong Shik [Fermilab; Stancari, Giulio [Fermilab
2017-02-02
Magnetized electron cooling at relativistic energies and Ampere scale current is essential to achieve the proposed ion luminosities in a future electron-ion collider (EIC). Neutralization of the space charge in such a cooler can significantly increase the magnetized dynamic friction and, hence, the cooling rate. The Warp framework is being used to simulate magnetized electron beam dynamics during and after the build-up of neutralizing ions, via ionization of residual gas in the cooler. The design follows previous experiments at Fermilab as a verification case. We also discuss the relevance to EIC designs.
Space-charge effects in high-energy photoemission
Energy Technology Data Exchange (ETDEWEB)
Verna, Adriano, E-mail: adriano.verna@uniroma3.it [Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); CNISM Unità di Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); Greco, Giorgia [Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); Lollobrigida, Valerio [Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); Scuola Dottorale in Matematica e Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); Offi, Francesco; Stefani, Giovanni [Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy); CNISM Unità di Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy)
2016-05-15
Highlights: • N-body simulations of interacting photoelectrons in hard X-ray experiments. • Secondary electrons have a pivotal role in determining the energy broadening. • Space charge has negligible effects on the photoelectron momentum distribution. • A simple model provides the characteristic time for energy-broadening mechanism. • The feasibility of time-resolved high-energy experiments with FELs is discussed. - Abstract: Pump-and-probe photoelectron spectroscopy (PES) with femtosecond pulsed sources opens new perspectives in the investigation of the ultrafast dynamics of physical and chemical processes at the surfaces and interfaces of solids. Nevertheless, for very intense photon pulses a large number of photoelectrons are simultaneously emitted and their mutual Coulomb repulsion is sufficiently strong to significantly modify their trajectory and kinetic energy. This phenomenon, referred as space-charge effect, determines a broadening and shift in energy for the typical PES structures and a dramatic loss of energy resolution. In this article we examine the effects of space charge in PES with a particular focus on time-resolved hard X-ray (∼10 keV) experiments. The trajectory of the electrons photoemitted from pure Cu in a hard X-ray PES experiment has been reproduced through N-body simulations and the broadening of the photoemission core-level peaks has been monitored as a function of various parameters (photons per pulse, linear dimension of the photon spot, photon energy). The energy broadening results directly proportional to the number N of electrons emitted per pulse (mainly represented by secondary electrons) and inversely proportional to the linear dimension a of the photon spot on the sample surface, in agreement with the literature data about ultraviolet and soft X-ray experiments. The evolution in time of the energy broadening during the flight of the photoelectrons is also studied. Despite its detrimental consequences on the energy
Estimation methods for nonlinear state-space models in ecology
DEFF Research Database (Denmark)
Pedersen, Martin Wæver; Berg, Casper Willestofte; Thygesen, Uffe Høgsbro
2011-01-01
The use of nonlinear state-space models for analyzing ecological systems is increasing. A wide range of estimation methods for such models are available to ecologists, however it is not always clear, which is the appropriate method to choose. To this end, three approaches to estimation in the theta...... logistic model for population dynamics were benchmarked by Wang (2007). Similarly, we examine and compare the estimation performance of three alternative methods using simulated data. The first approach is to partition the state-space into a finite number of states and formulate the problem as a hidden...... Markov model (HMM). The second method uses the mixed effects modeling and fast numerical integration framework of the AD Model Builder (ADMB) open-source software. The third alternative is to use the popular Bayesian framework of BUGS. The study showed that state and parameter estimation performance...
Enhancement and electric charge-assisted tuning of nonlinear light generation in bipolar plasmonics.
Ding, Wei; Zhou, Liangcheng; Chou, Stephen Y
2014-05-14
We propose and experimentally demonstrate a new plasmonic nonlinear light generation (NLG) structure, termed plasmonic-enhanced, charge-assisted second-harmonic generator (p-CASH), that not only achieves high second-harmonic generation (SHG) enhancement (76-fold), large SHG tunability by bias (8%/V), wide tuning range (280%), 7.8 × 10(-9) conversion efficiency, and high stability but also exhibits a SHG tuning, that is bipolar rather than unipolar, not due to the third-order nonlinear polarization term, hence fundamentally different from the classic electric field induced SHG-tuning (EFISH). We propose a new SHG tuning mechanism: the second-order nonlinear polarization term enhanced by plasmonic effects, changed by charge injection and negative oxygen vacancies movement, and is nearly 3 orders of magnitude larger than EFISH. p-CASH is a bipolar parallel-plate capacitor with thin layers of plasmonic nanostructures, a TiOx (semiconductor and nonlinear) and a SiO2 (insulator) sandwiched between two electrodes. Fabrication of p-CASH used nanoimprint on 4″ wafer and is scalable to wallpaper-sized areas. The new structure, new properties, and new understanding should open up various new designs and applications of NLG in various fields.
Al-Hindawi, Mohammed M.; Abusorrah, Abdullah; Al-Turki, Yusuf; Giaouris, Damian; Mandal, Kuntal; Banerjee, Soumitro
Photovoltaic (PV) systems with a battery back-up form an integral part of distributed generation systems and therefore have recently attracted a lot of interest. In this paper, we consider a system of charging a battery from a PV panel through a current mode controlled boost dc-dc converter. We analyze its complete nonlinear/nonsmooth dynamics, using a piecewise model of the converter and realistic nonlinear v-i characteristics of the PV panel. Through this study, it is revealed that system design without taking into account the nonsmooth dynamics of the converter combined with the nonlinear v-i characteristics of the PV panel can lead to unpredictable responses of the overall system with high current ripple and other undesirable phenomena. This analysis can lead to better designed converters that can operate under a wide variation of the solar irradiation and the battery's state of charge. We show that the v-i characteristics of the PV panel combined with the battery's output voltage variation can increase or decrease the converter's robustness, both under peak current mode control and average current mode control. We justify the observation in terms of the change in the discrete-time map caused by the nonlinear v-i characteristics of the PV panel. The theoretical results are validated experimentally.
Study on space charge compensation in negative hydrogen ion beam
Energy Technology Data Exchange (ETDEWEB)
Zhang, A. L.; Chen, J. E. [University of Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Peng, S. X., E-mail: sxpeng@pku.edu.cn; Ren, H. T.; Zhang, T.; Zhang, J. F.; Xu, Y.; Guo, Z. Y. [State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China)
2016-02-15
Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H{sup +} beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H{sup −} beam from a 2.45 GHz microwave driven H{sup −} ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.
Study on space charge compensation in negative hydrogen ion beam.
Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E
2016-02-01
Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.
Space-charge effects in liquid argon ionization chambers
Rutherfoord, J. P.; Walker, R. B.
2015-03-01
We have uniformly irradiated liquid argon ionization chambers with betas from high-activity 90Sr sources. The radiation environment is similar to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider (LHC). We measured the resulting ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. In particular they indicate a stability at the 0.1% level for these calorimeters over years of operation at the full LHC luminosity when operated in the normal mode at an electric field E = 1.0 kV / mm. We can operate these chambers in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. This transition point is parameterized by a positive argon ion mobility of μ+ = 0.08 ± 0.02mm2 / V s at a temperature of 88.0±0.5 K and at a pressure of 1.02±0.02 bar. In the space-charge limited regime the ionization currents are degraded and show signs of instability. At the highest electric fields in our study (6.7 kV/mm) the ionization current is still slowly rising with increasing electric field.
An FPGA computing demo core for space charge simulation
Energy Technology Data Exchange (ETDEWEB)
Wu, Jinyuan; Huang, Yifei; /Fermilab
2009-01-01
In accelerator physics, space charge simulation requires large amount of computing power. In a particle system, each calculation requires time/resource consuming operations such as multiplications, divisions, and square roots. Because of the flexibility of field programmable gate arrays (FPGAs), we implemented this task with efficient use of the available computing resources and completely eliminated non-calculating operations that are indispensable in regular micro-processors (e.g. instruction fetch, instruction decoding, etc.). We designed and tested a 16-bit demo core for computing Coulomb's force in an Altera Cyclone II FPGA device. To save resources, the inverse square-root cube operation in our design is computed using a memory look-up table addressed with nine to ten most significant non-zero bits. At 200 MHz internal clock, our demo core reaches a throughput of 200 M pairs/s/core, faster than a typical 2 GHz micro-processor by about a factor of 10. Temperature and power consumption of FPGAs were also lower than those of micro-processors. Fast and convenient, FPGAs can serve as alternatives to time-consuming micro-processors for space charge simulation.
Nonlinear sigma models with compact hyperbolic target spaces
Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; Stoica, Bogdan; Stokes, James
2016-06-01
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.
Nonlinear Evolution and Final Fate of Charged Anti-de Sitter Black Hole Superradiant Instability.
Bosch, Pablo; Green, Stephen R; Lehner, Luis
2016-04-08
We describe the full nonlinear development of the superradiant instability for a charged massless scalar field coupled to general relativity and electromagnetism, in the vicinity of a Reissner-Nordström-anti-de Sitter black hole. The presence of the negative cosmological constant provides a natural context for considering perfectly reflecting boundary conditions and studying the dynamics as the scalar field interacts repeatedly with the black hole. At early times, small superradiant perturbations grow as expected from linearized studies. Backreaction then causes the black hole to lose charge and mass until the perturbation becomes nonsuperradiant, with the final state described by a stable hairy black hole. For large gauge coupling, the instability extracts a large amount of charge per unit mass, resulting in greater entropy increase. We discuss the implications of the observed behavior for the general problem of superradiance in black hole spacetimes.
Energy Technology Data Exchange (ETDEWEB)
Belendez, A. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es; Fernandez, E. [Departamento de Optica, Farmacologia y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Rodes, J.J. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fuentes, R.; Pascual, I. [Departamento de Optica, Farmacologia y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2009-02-16
The harmonic balance method is used to construct approximate frequency-amplitude relations and periodic solutions to an oscillating charge in the electric field of a ring. By combining linearization of the governing equation with the harmonic balance method, we construct analytical approximations to the oscillation frequencies and periodic solutions for the oscillator. To solve the nonlinear differential equation, firstly we make a change of variable and secondly the differential equation is rewritten in a form that does not contain the square-root expression. The approximate frequencies obtained are valid for the complete range of oscillation amplitudes and excellent agreement of the approximate frequencies and periodic solutions with the exact ones are demonstrated and discussed.
Institute of Scientific and Technical Information of China (English)
LIN Chang; ZHANG Xiu-Lian
2005-01-01
The nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation is analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation.
Space-charge trapping and conduction in LDPE, HDPE and XLPE
Montanari, G. C.; Mazzanti, G.; Palmieri, F.; Motori, A.; Perego, G.; Serra, S.
2001-09-01
The mechanisms of charge injection, transport and trapping in low-density, high-density and cross-linked polyethylene (LDPE, HDPE and XLPE) are investigated in this paper through charging-discharging current measurements and space-charge observations. The conductivity of LDPE is much larger than that of XLPE and HDPE. The threshold for space-charge accumulation and that for a space-charge-limited current mechanism, coinciding for the same material, are almost identical for LDPE and HDPE, while the threshold of XLPE is higher. However, HDPE accumulates more charge than the other two materials. The depolarization space-charge curves and the conduction current versus field characteristics indicate that the mobility of LDPE is larger than that of XLPE and HDPE, which supports the significant difference in conductivity. The lower mobility, as well as the nature, depth and density of trap sites, can explain the difference in space-charge accumulation and thresholds.
Indian Academy of Sciences (India)
O Rahman; A A Mamun
2013-06-01
A theoretical investigation of dust-acoustic solitary waves in three-component unmagnetized dusty plasma consisting of trapped electrons, Maxwellian ions, and arbitrarily charged cold mobile dust was done. It has been found that, owing to the departure from the Maxwellian electron distribution to a vortex-like one, the dynamics of small but finite amplitude dust-acoustic (DA) waves is governed by a nonlinear equation of modified Korteweg–de Vries (mKdV) type (instead of KdV). The reductive perturbation method was employed to study the basic features (amplitude, width, speed, etc.) of DA solitary waves which are significantly modified by the presence of trapped electrons. The implications of our results in space and laboratory plasmas are briefly discussed.
Energy Technology Data Exchange (ETDEWEB)
Huang, Z. [Department of Physics, University of Arizona, Tucson, Arizona 85741 (United States); Suzuki, M. [Department of Physics and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
1996-01-01
We obtain the general solutions of the nonlinear {sigma} model in 3+1 dimensions as the candidates for the disoriented chiral condensate (DCC). The nonuniformly isospin-oriented solutions are shown to be related to the uniformly oriented ones through the chiral (axial) rotations. We discuss the pion charge distribution arising from these solutions. The distribution {ital dP}/{ital d}{ital f}=1/(2 {radical}{ital f} ) holds for the uniform solutions in general and the nonuniform solutions in the 1+1 boost-invariant case. For the nonuniform solution in 1+1 without boost invariance and in higher dimensions, the distribution does not hold in the integrated form. However, it is applicable to the pions selected from a small segment in the momentum phase space. We suggest that the nonuniform DCC{close_quote}s may correspond to the mini-Centauro events. {copyright} {ital 1996 The American Physical Society.}
A note on dust grain charging in space plasmas
Rosenberg, M.; Mendis, D. A.
1992-01-01
Central to the study of dust-plasma interactions in the solar system is the electrostatic charging of dust grains. While previous calculations have generally assumed that the distributions of electrons and ions in the plasma are Maxwellian, most space plasmas are observed to have non-Maxwellian tails and can often be fit by a generalized Lorentzian (kappa) distribution. Here we use such a distribution to reevaluate the grain potential, under the condition that the dominant currents to the grain are due to electron and ion collection, as is the case in certain regions of space. The magnitude of the grain potential is found to be larger than that in a Maxwellian plasma as long as the electrons are described by a kappa distribution: this enhancement increased with ion mass and decreasing electron kappa. The modification of the grain potential in generalized Lorentzian plasmas has implications for both the physics (e.g., grain growth and disruption) and the dynamics of dust in space plasmas. These are also briefly discussed.
Detailed numerical studies of space charge effects in an FEL RF gun
Cee, R R; Setzer, S; Weiland, T; Novokhatski, A
2002-01-01
The production of short bunches with low emittance is a key issue for the successful operation of an SASE-FEL as proposed by the TESLA collaboration (TESLA Technical design report, DESY 2001-011, Hamburg, 2001). In this paper we present the results of detailed MAFIA TS-2 (CST GmbH, Buedinger Strasse 2a, D-64289 Darmstadt) simulations for the FEL RF-gun revealing the main physical effects leading to emittance growth. The simulations prove that the transverse emittance growth can mainly be observed close to the cathode area. This is caused by the non-linear space charge forces acting inside the bunch during the injection process. For the application of an emittance compensation scheme (Nucl. Instr. and Meth. 285 (1989) 313) the slice emittance is of significant importance. Therefore, a wide range of parameters for the photo cathode laser has been investigated in order to find an appropriate operation point.
Non-stationary Effects In Space-charge Dominated Electron Beams
Agafonov, A V; Tarakanov, V P
2004-01-01
Problems of non-linear dynamics of space charge dominated electron beams in plane and in coaxial electron guns are discussed from the point of view of non-stationary behaviour of beams. The results of computer simulations of beam formation are presented for several simple plane diode geometries and for the gun with large compression of annular beam. Emphasised is non-stationary behaviour combined with edge and hysteresis effects. Non-stationary effects in crossed electron and magnetic field are considered from the point of view a development of schemes of intense electron beam formation for compact accelerators and RF-devices. The results of computer simulation of beam formation inside coaxial guns are described under condition of secondary self-sustaining emission. Possibilities of electron storage and capture due to transient processes are discussed. Work supported by RFBR under grant 03-02-17301.
Space Charge effects and mitigation in the CERN PS Booster, in view of the Upgrade
Benedetto, Elena; Forte, Vincenzo; Schmidt, Frank
2016-01-01
The CERN PS Booster (PSB) is presently running with a space charge tune spread larger than 0.5 at injection. Since the High Luminosity LHC (HL-LHC) will require beams with twice the intensity and brightness of today, the LHC Injector Upgrade (LIU) Project is putting in place an upgrade program for all the injector chain and, in particular, it relies on the important assumption that the PS Booster can successfully produce these beams after the implementation of the 160 MeV H- injection from Linac4. This contribution describes the studies (measure-ments and simulations) that have been carried out to con- firm that the PSB can indeed perform as needed in terms of beam brightness for the future HL-LHC runs. The importance of the mitigation measures already in place, such as the correction of the half-integer line, and the effects of non-linear resonances on the beam are also discussed.
Energy Technology Data Exchange (ETDEWEB)
Belendez, A., E-mail: a.belendez@ua.e [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)] [Instituto Universitario de Fisica Aplicada a las Ciencias y las Tecnologias, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E. [Departamento de Optica, Farmacologia y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Rodes, J.J. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fuentes, R.; Pascual, I. [Instituto Universitario de Fisica Aplicada a las Ciencias y las Tecnologias, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)] [Departamento de Optica, Farmacologia y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2009-11-09
In a previous short communication [A. Belendez, E. Fernandez, J.J. Rodes, R. Fuentes, I. Pascual, Phys. Lett. A 373 (2009) 735] the nonlinear oscillations of a punctual charge in the electric field of a charged ring were analyzed. Approximate frequency-amplitude relations and periodic solutions were obtained using the harmonic balance method. Now we clarify an important aspect about of this oscillation charge. Taking into account Earnshaw's theorem, this punctual charge cannot be a free charge and so it must be confined, for example, on a finite conducting wire placed along the axis of the ring. Then, the oscillatory system may consist of a punctual charge on a conducting wire placed along the axis of the uniformly charged ring.
Space-charge at the lithium-lithium chloride interface
Jamnik, J.; Gaberscek, M.; Meden, A.; Pejovnik, S.
1991-06-01
The electrical properties of the passive layer formed on lithium as the product of the corrosion reaction in thionyl chloride are discussed. The passive layer is regarded as a thin layer of an ionic crystal placed between two party blocking electrodes (i.e., lithium and liquid electrolyte). After a short review of thermodynamic properties of the system, a model for description of the electric properties of the static space-charge regions is presented. On this basis, a comment on and partial reinterpretation of impedance measurements of the passive layer is given. The suggested approach leads to the conclusion that the quality of Li/SOCl2 batteries decisively depends on the properties of the lithium passive layer interface. Finally, experiments to confirm the model are suggested.
TMCI threshold with space charge and different wake fields
Energy Technology Data Exchange (ETDEWEB)
Balbekov, V. [Fermilab
2016-08-22
Transverse mode coupling instability of a bunch with space charge and wake field is considered within the frameworks of the boxcar model. Eigenfunctions of the bunch without wake are used as a basis for the solution of the equations with the wake field included. A dispersion equation for constant wake is presented in the form of an infinite continued fraction and also as the recursive relation with an arbitrary number of the basis functions. Realistic wake fields are considered as well including resistive wall, square, and oscillating wakes. It is shown that the TMCI threshold of the negative wake grows up in absolute value when the SC tune shift increases. Threshold of positive wake goes down at the increasing SC tune shift. The explanation is developed by an analysis of the bunch spectrum.
Imaging charge-coupled devices for deep-space surveillance
Streuber, D. W., Jr.; Bailis, E. I.
1980-01-01
The Ground-Based Electro-Optical Deep Space Surveillance (GEODSS) system will employ a SIT vidicon camera to detect satellites. Imaging charge-coupled devices (CCDs) are being evaluated as a means to improve GEODSS capability. This paper presents performance models and uses them to evaluate currently available CCDs and to determine the characteristics of the ideal CCD array for GEODSS. The analysis includes an approach for determining the CCD pixel size which maximizes signal-to-noise ratio; this approach can be used in many applications. The impact of response nonuniformity and a simple compensation method are also discussed. The combination of a suitable CCD array, response nonuniformity compensation, and moving target indicator (MTI) processing is expected to substantially increase the detection and search rate capability of the GEODSS system.
Trapped-space-charge-limited currents in organics
Energy Technology Data Exchange (ETDEWEB)
Paasch, Gernot [IFW Dresden (Germany); Blom, Paul; Mandoc, Magda; Boer, Bert de [University of Groningen (Netherlands)
2007-07-01
The Mott-Gurney law for space charge limited current (SCLC) has been modified early to account for the presence of exponentially distributed traps. This expression has been widely used to analyse transport in organic light emitting diodes. However, the theory fails to describe the rather weak temperature dependence observed for electron transport, for instance in PPV derivatives. There we have shown that the trap-limited SCLC law is essentially modified if the density of transport states is of Gaussian type. Here, we discuss the origin of this modification and present a detailed analysis of the modified law. In addition, we derive further modifications for different combinations of densities of states of both the transport states and the trap distribution. As a result, rather different dependencies of the current on voltage, layer thickness and temperature are possible. Consequently, one has to exercise care in order to obtain reliable trap parameters from SCLC.
TMCI threshold with space charge and different wake fields
Balbekov, V
2016-01-01
Transverse mode coupling instability of a bunch with space charge and wake field is considered within the frameworks of the boxcar model. Eigenfunctions of the bunch without wake are used as a basis for the solution of the equations with the wake field included. A dispersion equation for constant wake is presented in the form of an infinite continued fraction and also as the recursive relation with an arbitrary number of the basis functions. Realistic wake fields are considered as well including resistive wall, square, and oscillating wakes. It is shown that the TMCI threshold of the negative wake grows up in absolute value when the SC tune shift increases. Threshold of positive wake goes down at the increasing SC tune shift. The explanation is developed by an analysis of the bunch spectrum.
Form Factor $g$ In Longitudinal Space Charge Impedance
Baartman, R
2015-01-01
In carrying out calculations of the effect of longitudinal space charge on longitudinal motion, the transverse beam size appears in a form factor which is usually written as $g=1+2\\ln (b/a)$. In fact, this expression applies to particles with vanishing betatron amplitude in a beam with uniform transverse distribution. It is argued that an average over the transverse distribution should be used instead of the value on axis. It is shown that for the realistic `binomial' family of distributions the 1 in the above expression for $g$ should be replaced by a value near 0.5 if $a$ is interpreted as twice the rms width of the beam.
A space-charge-neutralizing plasma for beam drift compression
Roy, P. K.; Seidl, P. A.; Anders, A.; Bieniosek, F. M.; Coleman, J. E.; Gilson, E. P.; Greenway, W.; Grote, D. P.; Jung, J. Y.; Leitner, M.; Lidia, S. M.; Logan, B. G.; Sefkow, A. B.; Waldron, W. L.; Welch, D. R.
2009-07-01
Simultaneous radial focusing and longitudinal compression of intense ion beams are being studied to heat matter to the warm dense matter, or strongly coupled plasma regime. Higher compression ratios can be achieved if the beam compression takes place in a plasma-filled drift region in which the space-charge forces of the ion beam are neutralized. Recently, a system of four cathodic arc plasma sources has been fabricated and the axial plasma density has been measured. A movable plasma probe array has been developed to measure the radial and axial plasma distribution inside and outside of a ˜10-cm-long final focus solenoid (FFS). Measured data show that the plasma forms a thin column of diameter ˜5 mm along the solenoid axis when the FFS is powered with an 8 T field. Measured plasma density of ⩾1×10 13 cm -3 meets the challenge of np/ Znb>1, where np and nb are the plasma and ion beam density, respectively, and Z is the mean ion charge state of the beam ions.
LARRAÑAGA, Eduard Alexis
2008-01-01
In this paper we will show that using the cosmological constant as a new thermodynamical state variable, the differential and integral mass formulas of the first law of thermodynamics for asymptotic flat spacetimes can be extended to (2+1) dimensional charged BTZ black holes and charged de Sitter space.
Directory of Open Access Journals (Sweden)
W. Dzwinel
2005-01-01
Full Text Available We present a novel technique based on a multi-resolutional clustering and nonlinear multi-dimensional scaling of earthquake patterns to investigate observed and synthetic seismic catalogs. The observed data represent seismic activities around the Japanese islands during 1997-2003. The synthetic data were generated by numerical simulations for various cases of a heterogeneous fault governed by 3-D elastic dislocation and power-law creep. At the highest resolution, we analyze the local cluster structures in the data space of seismic events for the two types of catalogs by using an agglomerative clustering algorithm. We demonstrate that small magnitude events produce local spatio-temporal patches delineating neighboring large events. Seismic events, quantized in space and time, generate the multi-dimensional feature space characterized by the earthquake parameters. Using a non-hierarchical clustering algorithm and nonlinear multi-dimensional scaling, we explore the multitudinous earthquakes by real-time 3-D visualization and inspection of the multivariate clusters. At the spatial resolutions characteristic of the earthquake parameters, all of the ongoing seismicity both before and after the largest events accumulates to a global structure consisting of a few separate clusters in the feature space. We show that by combining the results of clustering in both low and high resolution spaces, we can recognize precursory events more precisely and unravel vital information that cannot be discerned at a single resolution.
Nonlinear sigma models with compact hyperbolic target spaces
Energy Technology Data Exchange (ETDEWEB)
Gubser, Steven [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States); Saleem, Zain H. [Department of Physics and Astronomy, University of Pennsylvania,Philadelphia, PA 19104 (United States); National Center for Physics, Quaid-e-Azam University Campus,Islamabad 4400 (Pakistan); Schoenholz, Samuel S. [Department of Physics and Astronomy, University of Pennsylvania,Philadelphia, PA 19104 (United States); Stoica, Bogdan [Walter Burke Institute for Theoretical Physics, California Institute of Technology,452-48, Pasadena, CA 91125 (United States); Stokes, James [Department of Physics and Astronomy, University of Pennsylvania,Philadelphia, PA 19104 (United States)
2016-06-23
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model V.L. Berezinskii, Destruction of long-range order in one-dimensional and two-dimensional systems having a continuous symmetry group II. Quantum systems, Sov. Phys. JETP 34 (1972) 610. J.M. Kosterlitz and D.J. Thouless, Ordering, metastability and phase transitions in two-dimensional systems, J. Phys. C 6 (1973) 1181 [http://inspirehep.net/search?p=find+J+%22J.Phys.,C6,1181%22]. . Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
Energy Technology Data Exchange (ETDEWEB)
Hendi, S.H. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Panahiyan, S. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Panah, B.E.; Momennia, M. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)
2016-03-15
Motivated by the violation of Lorentz invariance in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain the related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered by an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally, we investigate the thermal stability conditions for these black hole solutions in the context of canonical ensemble. We show that the thermodynamical structure of the solutions depends on the choices of nonlinearity parameters, charge, and energy functions. (orig.)
Nonlinear interaction of charged particles with strong laser pulses in a gaseous media
Directory of Open Access Journals (Sweden)
H. K. Avetissian
2007-07-01
Full Text Available The charged particles nonlinear dynamics in the field of a strong electromagnetic wave pulse of finite duration and certain form of the envelope, in the refractive medium with a constant and variable refraction indexes, is investigated by means of numerical integration of the classical relativistic equations of motion. The particle energy dependence on the pulse intensity manifests the nonlinear threshold phenomenon of a particle reflection and capture by actual laser pulses in dielectric-gaseous media that takes place for a plane electromagnetic wave in the induced Cherenkov process. Laser acceleration of the particles in the result of the reflection from the pulse envelope and in the capture regime with the variable refraction index along the pulse propagation direction is investigated.
Bhakta, Subrata; Ghosh, Uttam; Sarkar, Susmita
2017-02-01
In this paper, we have investigated the effect of secondary electron emission on nonlinear propagation of dust acoustic waves in a complex plasma where equilibrium dust charge is negative. The primary electrons, secondary electrons, and ions are Boltzmann distributed, and only dust grains are inertial. Electron-neutral and ion-neutral collisions have been neglected with the assumption that electron and ion mean free paths are very large compared to the plasma Debye length. Both adiabatic and nonadiabatic dust charge variations have been separately taken into account. In the case of adiabatic dust charge variation, nonlinear propagation of dust acoustic waves is governed by the KdV (Korteweg-de Vries) equation, whereas for nonadiabatic dust charge variation, it is governed by the KdV-Burger equation. The solution of the KdV equation gives a dust acoustic soliton, whose amplitude and width depend on the secondary electron yield. Similarly, the KdV-Burger equation provides a dust acoustic shock wave. This dust acoustic shock wave may be monotonic or oscillatory in nature depending on the fact that whether it is dissipation dominated or dispersion dominated. Our analysis shows that secondary electron emission increases nonadiabaticity induced dissipation and consequently increases the monotonicity of the dust acoustic shock wave. Such a dust acoustic shock wave may accelerate charge particles and cause bremsstrahlung radiation in space plasmas whose physical process may be affected by secondary electron emission from dust grains. The effect of the secondary electron emission on the stability of the equilibrium points of the KdV-Burger equation has also been investigated. This equation has two equilibrium points. The trivial equilibrium point with zero potential is a saddle and hence unstable in nature. The nontrivial equilibrium point with constant nonzero potential is a stable node up to a critical value of the wave velocity and a stable focus above it. This critical
Unification of spins and charges in Grassmann space and in space of differential forms
Mankoc-Borstnik, Norma
2000-01-01
Polynomials in Grassmann space can be used to describe all the internal degrees of freedom of spinors, scalars and vectors, that is their spins and charges. It was shown that Kähler spinors, which are polynomials of differential forms, can be generalized to describe not only spins of spinors but also spins of vectors as well as spins and charges of scalars, vectors and spinors. If the space (ordinary and noncommutative) has 14 dimensions or more, the appropriate spontaneous break of symmetry leads gravity in $d$ dimensions to manifest in four dimensional subspace as ordinary gravity and all needed gauge fields as well as the Yukawa couplings. Both approaches, the Kähler's one (if generalized) and our, manifest four generations of massless fermions, which are left handed SU(2) doublets and right handed SU(2) singlets. In this talk a possible way of spontaneously broken symmetries is pointed out on the level of canonical momentum.
The role of space charge compensation for ion beam extraction and ion beam transport (invited)
Energy Technology Data Exchange (ETDEWEB)
Spädtke, Peter, E-mail: p.spaedtke@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany)
2014-02-15
Depending on the specific type of ion source, the ion beam is extracted either from an electrode surface or from a plasma. There is always an interface between the (almost) space charge compensated ion source plasma, and the extraction region in which the full space charge is influencing the ion beam itself. After extraction, the ion beam is to be transported towards an accelerating structure in most cases. For lower intensities, this transport can be done without space charge compensation. However, if space charge is not negligible, the positive charge of the ion beam will attract electrons, which will compensate the space charge, at least partially. The final degree of Space Charge Compensation (SCC) will depend on different properties, like the ratio of generation rate of secondary particles and their loss rate, or the fact whether the ion beam is pulsed or continuous. In sections of the beam line, where the ion beam is drifting, a pure electrostatic plasma will develop, whereas in magnetic elements, these space charge compensating electrons become magnetized. The transport section will provide a series of different plasma conditions with different properties. Different measurement tools to investigate the degree of space charge compensation will be described, as well as computational methods for the simulation of ion beams with partial space charge compensation.
Time-Dependent Phase-Space Mapping of Space-Charge-Dominated Beams
Energy Technology Data Exchange (ETDEWEB)
D. Stratakis, R.B. Fiorito, I. Haber, R.A. Kishek, P.G. O' Shea, M. Reiser, J.C.T. Thangaraj, K. Tian
2009-05-01
In this paper we report on a proof of principle experiment for demonstrating the possibility of reconstructing the time resolved-phase-space distribution of a space-charge dominated beam by a tomographic technique which provides us with far more information than a time-sliced emittance. We emphasize that this work describes and demonstrates a new methodology which can be applicable to any beam pulse using imaging methods with the appropriate time resolution for the pulse duration. The combination of a high precision tomographic diagnostic with fast imaging screens and a gated camera are used to produce phase space maps of two beams: one with a parabolic current profile and another with a short perturbation atop a rectangular pulse. The correlations between longitudinal and transverse phase spaces are apparent and their impact on the dynamics is discussed.
On a regular charged black hole with a nonlinear electric source
Culetu, Hristu
2014-01-01
A modified version of the Reissner-Nordstrom metric is proposed on the grounds of the nonlinear electrodynamics model. The source of curvature is an anisotropic fluid with $p_{r} = -\\rho$ which resembles the Maxwell stress tensor at $r >> q^{2}/2m$, where $q$ and $m$ are the mass and charge of the particle, respectively. We found the black hole horizon entropy obeys the relation $S = |W|/2T = A_{H}/4$, with $W$ the Komar energy and $A_{H}$ the horizon area. The electric field around the source depends not only on its charge but also on its mass. The corresponding electrostatic potential $\\Phi(r)$ is finite everywhere, vanishes at the origin and at $r = q^{2}/6m$ and is nonzero asymptotically, with $\\Phi_{\\infty} = 3m/2q$.
Linear and nonlinear waves on the charged surface of liquid hydrogen
Brazhnikov, M. Yu.; Kolmakov, G. V.; Levchenko, A. A.; Mezhov-Deglin, L. P.
2001-09-01
The results of research on the properties of linear and nonlinear waves on the charged surface of liquid hydrogen in a cylindrical cell are reported. It is found that the spectrum of oscillations of linear waves softens with increasing applied electric field. Weak turbulence in a system of capillary waves on the charged surface of liquid hydrogen is investigated. The formation of a Kolmogorov cascade is observed in the inertial interval from 100 Hz to 10 kHz. It is found that the correlation function of the deviation of the surface from its flat equilibrium state can be described by a power-law function of the frequency, with an exponent m=-3.7±0.3 when the surface is excited at a single resonance frequency, and m=-3.0±0.3 in the case of two-frequency excitation. The results of these studies are in qualitative agreement with the theoretical predictions.
Dymnikova, Irina
2015-01-01
In nonlinear electrodynamics coupled to gravity, regular spherically symmetric electrically charged solutions satisfy the weak energy condition and have obligatory de Sitter centre. By the G\\"urses-G\\"ursey algorithm they are transformed to spinning electrically charged solutions asymptotically Kerr-Newman for a distant observer. Rotation transforms de Sitter center into de Sitter vacuum surface which contains equatorial disk $r=0$ as a bridge. We present general analysis of the horizons, ergoregions and de Sitter surfaces, as well as the conditions of the existence of regular solutions to the field equations. We find asymptotic solutions and show that de Sitter vacuum surfaces have properties of a perfect conductor and ideal diamagnetic, violation of the weak energy condition is prevented by the basic requirement of electrodynamics of continued media, and the Kerr ring singularity is replaced with the superconducting current.
Modeling Charge-Sign Asymmetric Solvation Free Energies With Nonlinear Boundary Conditions
Bardhan, Jaydeep P
2014-01-01
We show that charge-sign-dependent asymmetric hydration can be modeled accurately using linear Poisson theory but replacing the standard electric-displacement boundary condition with a simple nonlinear boundary condition. Using a single multiplicative scaling factor to determine atomic radii from molecular dynamics Lennard-Jones parameters, the new model accurately reproduces MD free-energy calculations of hydration asymmetries for (i) monatomic ions, (ii) titratable amino acids in both their protonated and unprotonated states, and (iii) the Mobley "bracelet" and "rod" test problems [J. Phys. Chem. B, v. 112:2408, 2008]. Remarkably, the model also justifies the use of linear response expressions for charging free energies. Our boundary-element method implementation demonstrates the ease with which other continuum-electrostatic solvers can be extended to include asymmetry.
Progress of Space Charge Research on Oil-Paper Insulation Using Pulsed Electroacoustic Techniques
Directory of Open Access Journals (Sweden)
Chao Tang
2016-01-01
Full Text Available This paper focuses on the space charge behavior in oil-paper insulation systems used in power transformers. It begins with the importance of understanding the space charge behavior in oil-paper insulation systems, followed by the introduction of the pulsed electrostatic technique (PEA. After that, the research progress on the space charge behavior of oil-paper insulation during the recent twenty years is critically reviewed. Some important aspects such as the environmental conditions and the acoustic wave recovery need to be addressed to acquire more accurate space charge measurement results. Some breakthroughs on the space charge behavior of oil-paper insulation materials by the research team at the University of Southampton are presented. Finally, future work on space charge measurement of oil-paper insulation materials is proposed.
Identification of a Class of Non-linear State Space Models using RPE Techniques
DEFF Research Database (Denmark)
Zhou, Wei-Wu; Blanke, Mogens
1989-01-01
The RPE (recursive prediction error) method in state-space form is developed in the nonlinear systems and extended to include the exact form of a nonlinearity, thus enabling structure preservation for certain classes of nonlinear systems. Both the discrete and the continuous-discrete versions...... of the algorithm in an innovations model are investigated, and a nonlinear simulation example shows a quite convincing performance of the filter as combined parameter and state estimator...
An analytical approach to space charge distortions for time projection chambers
Rossegger, S; Riegler, W
2010-01-01
In a time projection chamber (TPC), the possible ion feedback and also the primary ionization of high multiplicity events result in accumulation of ionic charges inside the gas volume (space charge). This charge introduces electrical field distortions and modifies the cluster trajectory along the drift path, affecting the tracking performance of the detector. In order to calculate the track distortions due to an arbitrary space charge distribution in the TPC, novel representations of the Green's function for a TPC geometry were worked out. This analytical approach finally permits accurate predictions of track distortions due to an arbitrary space charge distribution by solving the Langevin equation.
Charge flipping vortices in the discrete nonlinear Schrödinger trimer and hexamer
Jason, Peter; Johansson, Magnus
2015-02-01
We examine the existence and properties of charge flipping vortices (CFVs), vortices which periodically flip the topological charge, in three-site (trimer) and six-site (hexamer) discrete nonlinear Schrödinger lattices. We demonstrate numerically that CFVs exist as exact quasiperiodic solutions in continuous families which connect two different stationary solutions without topological charge, and that it is possible to interpret the dynamics of certain CFVs as the result of perturbations of these stationary solutions. The CFVs are calculated with high numerical accuracy and we may therefore accurately determine many of their properties, such as their energy and linear stability, and the CFVs are found to be stable over large parameter regimes. We also show that, like in earlier studies for lattices with a multiple of four sites, trimer and hexamer CFVs can be obtained by perturbing stationary constant amplitude vortices with certain linear eigenmodes. However, in contrast to the former case where the perturbation could be infinitesimal, the magnitude of the perturbations for trimers and hexamers must overcome a quite large threshold value. These CFVs may be interpreted as exact quasiperiodic CFVs, with a small perturbation applied. The concept of a charge flipping energy barrier is introduced and discussed.
Tomographic measurement of the phase space distribution of a space-charge-dominated beam
Stratakis, Diktys
Many applications of accelerators, such as free electron lasers, pulsed neutron sources, and heavy ion fusion, require a good quality beam with high intensity. In practice, the achievable intensity is often limited by the dynamics at the low-energy, space-charge dominated end of the machine. Because low-energy beams can have complex distribution functions, a good understanding of their detailed evolution is needed. To address this issue, we have developed a simple and accurate tomographic method to map the beam phase using quadrupole magnets, which includes the effects from space charge. We extend this technique to use also solenoidal magnets which are commonly used at low energies, especially in photoinjectors, thus making the diagnostic applicable to most machines. We simulate our technique using a particle in cell code (PIC), to ascertain accuracy of the reconstruction. Using this diagnostic we report a number of experiments to study and optimize injection, transport and acceleration of intense space charge dominated beams. We examine phase mixing, by studying the phase-space evolution of an intense beam with a transversely nonuniform initial density distribution. Experimental measurements, theoretical predictions and PIC simulations are in good agreement each other. Finally, we generate a parabolic beam pulse to model those beams from photoinjectors, and combine tomography with fast imaging techniques to investigate the time-sliced parameters of beam current, size, energy spread and transverse emittance. We found significant differences between the slice emittance profiles and slice orientation as the beam propagates downstream. The combined effect of longitudinal nonuniform profiles and fast imaging of the transverse phase space provided us with information about correlations between longitudinal and transverse dynamics that we report within this dissertation.
Benchmark of ACCSIM-ORBIT codes for space charge and electron-lens compensation
Masamitsu, Aiba
2008-01-01
Numerical simulation is a possible approach to evaluate and to understand space charge effects in the CERN injector chain for the LHC. Several codes to simulate space charge effects have been developed, and we performed a benchmark of ACCSIM [1] and ORBIT [2] in this study. The study is highly motivated since beam losses and/or deteriorations in beam quality due to space charge effects are not negligible or sometimes considerable in the complex, especially in the Proton Synchrotron Booster. We also discuss a possibility of compensation of space charge effects by applying “electron-lens”.
Franchetti, Giuliano; Huschauer, Alexander; Schmidt, Frank; Wasef, Raymond
2017-01-01
The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response: in the vertical plane the beam exhibits a thick halo, while the horizontal profile has only core growth. The quest for explaining these results requires a journey through the 4 dimensional dynamics of the coupled resonance investigating the fixed-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This proceeding gives a short summary of the experimental results of the 2012 PS measurements, and address an interpretation based on the dynamics the fixed-lines.
Energy Technology Data Exchange (ETDEWEB)
Li, Jin [Chongqing University, Department of Physics, Chongqing (China); Lin, Kai [Universidade de Sao Paulo, Instituto de Fisica, CP 66318, Sao Paulo (Brazil); Yang, Nan [Huazhong University of Science and Technology, Department of Physics, Wuhan (China)
2015-03-01
Based on a regular exact black hole (BH) from nonlinear electrodynamics (NLED) coupled to general relativity, we investigate the stability of such BH through the Quasinormal Modes (QNMs) of electromagnetic (EM) field perturbations and its thermodynamics through Hawking radiation. In perturbation theory, we can deduce the effective potential from a nonlinear EM field. The comparison of the potential function between regular and RN BHs could predict similar QNMs. The QNM frequencies tell us the effect of the magnetic charge q, the overtone n, and the angular momentum number l on the dynamic evolution of NLED EM field. Furthermore we also discuss the cases of near-extreme conditions of such a magnetically charged regular BH. The corresponding QNM spectrum illuminates some special properties in the near-extreme cases. For the thermodynamics, we employ the Hamilton-Jacobi method to calculate the near-horizon Hawking temperature of the regular BH and reveal the relationship between the classical parameters of the black hole and its quantum effects. (orig.)
Blas, H; Vilela, A M
2016-01-01
Deformations of the focusing non-linear Schr\\"odinger model (NLS) are considered in the context of the quasi-integrability concept. We strengthen the results of JHEP09(2012)103 for bright soliton collisions. We addressed the focusing NLS as a complement to the one in JHEP03(2016)005, in which the modified defocusing NLS models with dark solitons were shown to exhibit an infinite tower of exactly conserved charges. We show, by means of analytical and numerical methods, that for certain two-bright-soliton solutions, in which the modulus and phase of the complex modified NLS field exhibit even parities under a space-reflection symmetry, the first four and the sequence of even order charges are exactly conserved during the scattering process of the solitons. We perform extensive numerical simulations and consider the bright solitons with deformed potential $ V = \\frac{ 2\\eta}{2+ \\epsilon} \\( |\\psi|^2\\)^{2 + \\epsilon}, \\epsilon \\in \\IR, \\eta<0$. However, for two-soliton field components without definite parity ...
Directory of Open Access Journals (Sweden)
Raicharan Denra
2016-12-01
Full Text Available In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
Denra, Raicharan; Paul, Samit; Sarkar, Susmita
2016-12-01
In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
ISS Charging Hazards and Low Earth Orbit Space Weather Effects
Minow, Joseph; Parker, L.; Coffey, V.; Wright K.; Koontz, S.; Edwards, D.
2008-01-01
Current collection by high voltage solar arrays on the International Space Station (ISS) drives the vehicle to negative floating potentials in the low Earth orbit daytime plasma environment. Pre-flight predictions of ISS floating potentials Phi greater than |-100 V| suggested a risk for degradation of dielectric thermal control coatings on surfaces in the U.S. sector due to arcing and an electrical shock hazard to astronauts during extravehicular activity (EVA). However, hazard studies conducted by the ISS program have demonstrated that the thermal control material degradation risk is effectively mitigated during the lifetime of the ISS vehicle by a sufficiently large ion collection area present on the vehicle to balance current collection by the solar arrays. To date, crew risk during EVA has been mitigated by operating one of two plasma contactors during EVA to control the vehicle potential within Phi less than or equal to |-40 V| with a backup process requiring reorientation of the solar arrays into a configuration which places the current collection surfaces into wake. This operation minimizes current collection by the solar arrays should the plasma contactors fail. This paper presents an analysis of F-region electron density and temperature variations at low and midlatitudes generated by space weather events to determine what range of conditions represent charging threats to ISS. We first use historical ionospheric plasma measurements from spacecraft operating at altitudes relevant to the 51.6 degree inclination ISS orbit to provide an extensive database of F-region plasma conditions over a variety of solar cycle conditions. Then, the statistical results from the historical data are compared to more recent in-situ measurements from the Floating Potential Measurement Unit (FPMU) operating on ISS in a campaign mode since its installation in August, 2006.
Nonlinear Landau-Zener tunneling in quantum phase space
Energy Technology Data Exchange (ETDEWEB)
Trimborn, F [Institut fuer theoretische Physik, Leibniz Universitaet Hannover, D-30167 Hannover (Germany); Witthaut, D [QUANTOP, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Kegel, V; Korsch, H J, E-mail: friederike.trimborn@itp.uni-hannover.d [Fachbereich Physik, TU Kaiserslautern, D-67663 Kaiserslautern (Germany)
2010-05-15
We present a detailed analysis of the Landau-Zener problem for an interacting Bose-Einstein condensate in a time-varying double-well trap, especially focusing on the relation between the full many-particle problem and the mean-field approximation. Due to the nonlinear self-interaction a dynamical instability occurs, which leads to a breakdown of adiabaticity and thus fundamentally alters the dynamics. It is shown that essentially all the features of the Landau-Zener problem including the depletion of the condensate mode can be already understood within a semiclassical phase-space picture. In particular, this treatment resolves the formerly imputed incommutability of the adiabatic and semiclassical limits. The possibility of exploiting Landau-Zener sweeps to generate squeezed states for spectroscopic tasks is analyzed in detail. Moreover, we study the influence of phase noise and propose a Landau-Zener sweep as a sensitive yet readily implementable probe for decoherence, since the noise has significant effect on the transition rate for slow parameter variations.
Nonlinear Landau-Zener tunneling in quantum phase space
Trimborn, F; Kegel, V; Korsch, H J; 10.1088/1367-2630/12/5/053010
2010-01-01
We present a detailed analysis of the Landau-Zener problem for an interacting Bose-Einstein condensate in a time-varying double-well trap, especially focussing on the relation between the full many-particle problem and the mean-field approximation. Due to the nonlinear self-interaction a dynamical instability occurs, which leads to a breakdown of adiabaticity condition and thus fundamentally alters the dynamics. It is shown that essentially all features of the Landau-Zener problem including the depletion of the condensate mode can be already understood within a semiclassical phase space picture. In particular, this treatment resolves the formerly imputed incommutability of the adiabatic and semiclassical limits. The possibility to exploit Landau-Zener sweeps to generate squeezed states for spectroscopic tasks is analysed in detail. Moreover, we study the influence of phase noise and propose a Landau-Zener sweep as a sensitive, yet readily implementable probe for decoherence, since this has a significant effec...
Thickness scaling of the space-charge-limited current in poly(p-phenylene vinylene)
Blom, PWM; Tanase, C; de Leeuw, DM; Coehoorn, R
2005-01-01
Charge transport in light-emitting diodes (LEDs) based on a polyp-phenylene vinylene) (PPV) derivative is investigated as a function of sample thickness. Via the thickness dependence, the contributions from the electric field and charge carrier density to the mobility in space-charge-limited (SCL) d
The effect of dc poling duration on space charge relaxation in virgin XLPE cable peelings
Energy Technology Data Exchange (ETDEWEB)
Tzimas, Antonios; Rowland, Simon M [University of Manchester, School of Electrical and Electronic Engineering, Manchester, M60 1QD (United Kingdom); Dissado, Leonard A [University of Leicester, Department of Engineering, Leicester, LE1 7RH (United Kingdom); Fu, Mingli [AREVA T and D UK Limited, St Leonards Avenue, Stafford, ST17 4LX (United Kingdom); Nilsson, Ulf H, E-mail: Antonios.Tzimas@manchester.ac.u [Borealis AB, SE-444 86, Stenungsund (Sweden)
2010-06-02
The effect of dc poling time upon the time-dependent decay of space charge in insulation peelings of cross-linked polyethylene (XLPE) cable that had not previously experienced either electrical or thermal stressing is investigated. Two dc poling durations were used, 2 h and 26 h at an electric field of 50 kV mm{sup -1} and at ambient temperature. Space charge was measured in the two samples investigated both during space charge accumulation and throughout its subsequent decay. The results show that the length of dc poling plays an important role in the subsequent decay. Despite the fact that both samples have had the same amount of space charge by the end of both short and long poling durations the time dependence of the space charge decay is different. Most of the charge stored in the sample that had experienced the short time poling decays rapidly after voltage removal. On the other hand, the charge that is stored in the sample with the long dc poling duration decays slowly and its decay occurs in two stages. The data, which are analysed by means of the de-trapping theory of space charge decay, imply that the charge stored in the material has occupied energy states with different trap depth ranges. The two poling durations lead to different relative amounts of charge in each of the two trap depth ranges. Possible reasons for this are discussed.
The effect of dc poling duration on space charge relaxation in virgin XLPE cable peelings
Tzimas, Antonios; Rowland, Simon M.; Dissado, Leonard A.; Fu, Mingli; Nilsson, Ulf H.
2010-06-01
The effect of dc poling time upon the time-dependent decay of space charge in insulation peelings of cross-linked polyethylene (XLPE) cable that had not previously experienced either electrical or thermal stressing is investigated. Two dc poling durations were used, 2 h and 26 h at an electric field of 50 kV mm-1 and at ambient temperature. Space charge was measured in the two samples investigated both during space charge accumulation and throughout its subsequent decay. The results show that the length of dc poling plays an important role in the subsequent decay. Despite the fact that both samples have had the same amount of space charge by the end of both short and long poling durations the time dependence of the space charge decay is different. Most of the charge stored in the sample that had experienced the short time poling decays rapidly after voltage removal. On the other hand, the charge that is stored in the sample with the long dc poling duration decays slowly and its decay occurs in two stages. The data, which are analysed by means of the de-trapping theory of space charge decay, imply that the charge stored in the material has occupied energy states with different trap depth ranges. The two poling durations lead to different relative amounts of charge in each of the two trap depth ranges. Possible reasons for this are discussed.
Two-dimensional relativistic space charge limited current flow in the drift space
Energy Technology Data Exchange (ETDEWEB)
Liu, Y. L.; Chen, S. H., E-mail: chensh@ncu.edu.tw [Department of Physics, National Central University, Jhongli 32001, Taiwan (China); Koh, W. S. [A-STAR Institute of High Performance Computing, Singapore 138632 (Singapore); Ang, L. K. [Engineering Product Development, Singapore University of Technology and Design, Singapore 138682 (Singapore)
2014-04-15
Relativistic two-dimensional (2D) electrostatic (ES) formulations have been derived for studying the steady-state space charge limited (SCL) current flow of a finite width W in a drift space with a gap distance D. The theoretical analyses show that the 2D SCL current density in terms of the 1D SCL current density monotonically increases with D/W, and the theory recovers the 1D classical Child-Langmuir law in the drift space under the approximation of uniform charge density in the transverse direction. A 2D static model has also been constructed to study the dynamical behaviors of the current flow with current density exceeding the SCL current density, and the static theory for evaluating the transmitted current fraction and minimum potential position have been verified by using 2D ES particle-in-cell simulation. The results show the 2D SCL current density is mainly determined by the geometrical effects, but the dynamical behaviors of the current flow are mainly determined by the relativistic effect at the current density exceeding the SCL current density.
Rana, Meenakshi; Singla, Nidhi; Chatterjee, Amrita; Shukla, Abhishek; Chowdhury, Papia
2016-12-01
Nonlinear Optical (NLO) properties of amine functionalized tetraphenylethylene (TPE-NH2) have been recorded and analyzed. The structural geometry, bonding features, harmonic vibrational frequencies (FTIR and Raman) of TPE-NH2 have been investigated by B3LYP density functional theory (DFT). Charge (Mulliken and natural) analysis, natural bond orbital (NBO) analysis, frontier molecular orbitals (FMOs), 13C and 1H nuclear magnetic resonance (NMR) and molecular electrostatic potential (MEP) indicate the delocalization of charges over the donor-acceptor region by the increase of C-N bond length. The vibrational analysis on the basis of potential energy distribution (PED) confirms the charge transfer interaction between donor and acceptor groups, and that in turn validates the presence of the larger dipole moment (μ), polarizability and hyperpolarizabilities (α, β and γ) in TPE-NH2. Higher value of ionization potential (IP), electronegativity (χ), hardness (η), chemical potential (CP) and smaller HOMO-LUMO energy gap (Δε) validate TPE-NH2's strong candidature to be used as an NLO active material.
Identification of a class of nonlinear state-space models using RPE techniques
DEFF Research Database (Denmark)
Zhou, W. W.; Blanke, Mogens
1986-01-01
The recursive prediction error methods in state-space form have been efficiently used as parameter identifiers for linear systems, and especially Ljung's innovations filter using a Newton search direction has proved to be quite ideal. In this paper, the RPE method in state-space form is developed...... to the nonlinear case and extended to include the exact form of a nonlinearity, thus enabling structure preservation for certain classes of nonlinear systems. Both the discrete and the continuous-discrete versions of the algorithm in an innovations model are investigated, and a nonlinear simulation example shows...... a quite convincing performance of the filter as combined parameter and state estimator....
Energy Technology Data Exchange (ETDEWEB)
Meili, G.; Dubroca, G.; Pasquier, M.; Thepenier, J.
1982-06-01
The paper discusses a method for the mechanical testing of casebonded composite modified double base charges (CMDB) subjected to thermal cycling. The method proposed to determine stresses and safety margins takes into account the non-linear viscoelastic behaviour and the compressibility of the propellant. The non-linear behaviour is derived from tensile testing. The equations of equilibrium are solved numerically by deviding the grain web into many layers. The nonlinearities mainly concern the modulus; a multiaxial criterion and the time-temperature shift factors are used. At each time-step and for each layer the temperature, the reduced time, the non-linear factor, the Poisson's ratio and the damage according to the concept of Farris are calculated. Different charges (star, wagon wheel, finocyl) were subjected to various types of thermal cycles. The comparison between prediction and experimentation is acceptable even for complex histories in strain and temperature.
Energy Technology Data Exchange (ETDEWEB)
Valdeblanquez, Eder [Departamento de Fisica, Facultad de IngenierIa, Universidad del Zulia, Apartado 4011- A 526, Maracaibo, Venezuela and Centro de Investigacion de Matematicas Aplicadas Facultad de IngenierIa, Universidad del Zulia, Apartado 10486, Maracaibo (Venezuela, Bolivarian Republic of)], E-mail: eder@luz.edu.ve
2008-10-15
In this paper the space-charge effects in Langmuir probes are compared for different kinds of symmetries: plane, cylindrical and spherical. A detailed analysis is performed here including temperature effects, and therefore kinetic theory is used instead of fluid equations as used by other authors. The nonlinear equations obtained here have been solved first by numerical computation and later by approximations using Bessel functions. The accuracy of each approximation is also discussed. Space-charge effects are more important in plane geometries than in the case of cylindrical or spherical symmetries.
Bazarov, Ivan V; Gulliford, Colwyn; Li, Yulin; Liu, Xianghong; Sinclair, Charles K; Soong, Ken; Hannon, Fay
2008-01-01
We present a comparison between space charge calculations and direct measurements of the transverse phase space for space charge dominated electron bunches after a high voltage photoemission DC gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit setup for a set of parameters such as charge per bunch and the solenoid current. The data is compared with detailed simulations using 3D space charge codes GPT and Parmela3D with initial particle distributions created from the measured transverse and temporal laser profiles. Beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach the theoretical maximum set by the thermal energy and accelerating field at the photocathode.
Directory of Open Access Journals (Sweden)
Ivan V. Bazarov
2008-10-01
Full Text Available We present a comparison between space charge calculations and direct measurements of the transverse phase space of space charge dominated electron bunches from a high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit emittance measurement system over a range of bunch charge and solenoid current values. The data are compared with detailed simulations using the 3D space charge codes GPT and Parmela3D. The initial particle distributions were generated from measured transverse and temporal laser beam profiles at the photocathode. The beam brightness as a function of beam fraction is calculated for the measured phase space maps and found to approach within a factor of 2 the theoretical maximum set by the thermal energy and the accelerating field at the photocathode.
The role of space charge in GaAs-based particle detectors
Mares, J J; Hubik, P; Pospísil, S
1999-01-01
The direct measurement of the captured charge using the Faraday cup method together with the analysis of current-voltage curves was used for the experimental proof of the existence of the space charge in biased GaAs detector structures. The role of this space charge was discussed using the generalized Ramo-Gunn's theorem which enabled the explanation of the data observed and, moreover, provides a useful criterion for the optimization of GaAs-based particle detectors. (author)
Analytical approximate solution for nonlinear space-time fractional Klein-Gordon equation
Institute of Scientific and Technical Information of China (English)
Khaled A.Gepreel; Mohamed S.Mohamed
2013-01-01
The fractional derivatives in the sense of Caputo and the homotopy analysis method are used to construct an approximate solution for the nonlinear space-time fractional derivatives Klein-Gordon equation.The numerical results show that the approaches are easy to implement and accurate when applied to the nonlinear space-time fractional derivatives KleinGordon equation.This method introduces a promising tool for solving many space-time fractional partial differential equations.This method is efficient and powerful in solving wide classes of nonlinear evolution fractional order equations.
Magnetic charge lattices, moduli spaces and fusion rules
Kampmeijer, L.; Slingerland, J.K.; Schroers, B.J.; Bais, F.A.
2009-01-01
We analyze the labelling and fusion properties of magnetic charge sectors consisting of smooth BPS monopoles in Yang-Mills-Higgs theory with arbitrary gauge group G spontaneously broken to a subgroup H. The magnetic charges are restricted by a generalized Dirac quantization condition and by an inequ
Evidence of Space-Charge Effects in Thermal Poling
DEFF Research Database (Denmark)
Wu, X.; Arentoft, Jesper; Wong, D.
1999-01-01
ionization. Both the shielding electrical field due to charge migration and the ionization electrical field due to charge ionization are able to be frozen-in at room temperature acid lead to the residual linear electrooptic effects, The observations support that the mechanism of the induced electrooptic...
Space charge accumulation in polymeric high voltage DC cable systems
Bodega, R.
2006-01-01
One of the intrinsic properties of the polymeric high voltage (HV) direct current (DC) cable insulation is the accumulation of electrostatic charges. Accumulated charges distort the initial Laplacian distribution of the electric field, leading to a local field enhancement that may cause insulation d
A Symplectic Multi-Particle Tracking Model for Self-Consistent Space-Charge Simulation
Qiang, Ji
2016-01-01
Symplectic tracking is important in accelerator beam dynamics simulation. So far, to the best of our knowledge, there is no self-consistent symplectic space-charge tracking model available in the accelerator community. In this paper, we present a two-dimensional and a three-dimensional symplectic multi-particle spectral model for space-charge tracking simulation. This model includes both the effect from external fields and the effect of self-consistent space-charge fields using a split-operator method. Such a model preserves the phase space structure and shows much less numerical emittance growth than the particle-in-cell model in the illustrative examples.
Reeta Felscia, U.; Rajkumar, Beulah J. M.; Sankar, Pranitha; Philip, Reji; Briget Mary, M.
2017-09-01
The interaction of pyrene on silver has been investigated using both experimental and computational methods. Hyperpolarizabilities computed theoretically together with experimental nonlinear absorption from open aperture Z-scan measurements, point towards a possible use of pyrene adsorbed on silver in the rational design of NLO devices. Presence of a red shift in both simulated and experimental UV-Vis spectra confirms the adsorption on silver, which is due to the electrostatic interaction between silver and pyrene, inducing variations in the structural parameters of pyrene. Fukui calculations along with MEP plot predict the electrophilic nature of the silver cluster in the presence of pyrene, with NBO analysis revealing that the adsorption causes charge redistribution from the first three rings of pyrene towards the fourth ring, from where the 2p orbitals of carbon interact with the valence 5s orbitals of the cluster. This is further confirmed by the downshifting of ring breathing modes in both the experimental and theoretical Raman spectra.
Yamasue, Kohei; Fukidome, Hirokazu; Funakubo, Kazutoshi; Suemitsu, Maki; Cho, Yasuo
2015-06-05
We investigate pristine and hydrogen-intercalated graphene synthesized on a 4H-SiC(0001) substrate by using noncontact scanning nonlinear dielectric potentiometry (NC-SNDP). Permanent dipole moments are detected at the pristine graphene-SiC interface. These originate from the covalent bonds of carbon atoms of the so-called buffer layer to the substrate. Hydrogen intercalation at the interface eliminates these covalent bonds and the original quasi-(6×6) corrugation, which indicates the conversion of the buffer layer into a second graphene layer by the termination of Si bonds at the interface. NC-SNDP images suggest that a certain portion of the Si dangling bonds remains even after hydrogen intercalation. These bonds are thought to act as charged impurities reducing the carrier mobility in hydrogen-intercalated graphene on SiC.
Electric vehicle state of charge estimation: Nonlinear correlation and fuzzy support vector machine
Sheng, Hanmin; Xiao, Jian
2015-05-01
The aim of this study is to estimate the state of charge (SOC) of the lithium iron phosphate (LiFePO4) battery pack by applying machine learning strategy. To reduce the noise sensitive issue of common machine learning strategies, a kind of SOC estimation method based on fuzzy least square support vector machine is proposed. By applying fuzzy inference and nonlinear correlation measurement, the effects of the samples with low confidence can be reduced. Further, a new approach for determining the error interval of regression results is proposed to avoid the control system malfunction. Tests are carried out on modified COMS electric vehicles, with two battery packs each consists of 24 50 Ah LiFePO4 batteries. The effectiveness of the method is proven by the test and the comparison with other popular methods.
Yamasue, Kohei; Fukidome, Hirokazu; Funakubo, Kazutoshi; Suemitsu, Maki; Cho, Yasuo
2015-06-01
We investigate pristine and hydrogen-intercalated graphene synthesized on a 4 H -SiC (0001 ) substrate by using noncontact scanning nonlinear dielectric potentiometry (NC-SNDP). Permanent dipole moments are detected at the pristine graphene-SiC interface. These originate from the covalent bonds of carbon atoms of the so-called buffer layer to the substrate. Hydrogen intercalation at the interface eliminates these covalent bonds and the original quasi-(6 ×6 ) corrugation, which indicates the conversion of the buffer layer into a second graphene layer by the termination of Si bonds at the interface. NC-SNDP images suggest that a certain portion of the Si dangling bonds remains even after hydrogen intercalation. These bonds are thought to act as charged impurities reducing the carrier mobility in hydrogen-intercalated graphene on SiC.
A dual approach in Orlicz spaces for the nonlinear Helmholtz equation
Evéquoz, Gilles
2015-12-01
In this paper, we present a variational framework in Orlicz spaces for the study of the nonlinear Helmholtz equation - Δ{u} - k2 u = f(x,u),quad {x} in {R}^N where N ≥ 3, k > 0 and f is a superlinear but subcritical nonlinearity, and we prove the existence of infinitely many real-valued solutions under additional decay assumptions on the nonlinear term. We also derive a far-field relation for these solutions.
Filicori, Fabio; Traverso, Pier Andrea; Florian, Corrado; Borgarino, Mattia
2004-05-01
The basic features of the recently proposed Charge-Controlled Non-linear Noise (CCNN) model for the prediction of low-to-high-frequency noise up-conversion in electron devices under large-signal RF operation are synthetically presented. It is shown that the different noise generation phenomena within the device can be described by four equivalent noise sources, which are connected at the ports of a "noiseless" device model and are non-linearly controlled by the time-varying instantaneous values of the intrinsic device voltages. For the empirical identification of the voltage-controlled equivalent noise sources, different possible characterization procedures, based not only on conventional low-frequency noise data, but also on different types of noise measurements carried out under large-signal RF operating conditions are discussed. As an example of application, the measurement-based identification of the CCNN model for a GaInP heterojunction bipolar microwave transistor is presented. Preliminary validation results show that the proposed model can describe with adequate accuracy not only the low-frequency noise of the HBT, but also its phase-noise performance in a prototype VCO implemented by using the same monolithic GaAs technology.
Sheykhi, A; Zangeneh, M Kord
2016-01-01
We construct a new class of charged rotating black brane solutions in the presence of logarithmic nonlinear electrodynamics with complete set of the rotation parameters in arbitrary dimensions. The topology of the horizon of these rotating black branes are flat, while, due to the presence of the dilaton field the asymptotic behaviour of them are neither flat nor (anti)-de Sitter [(A)dS]. We investigate the physical properties of the solutions. The mass and angular momentum of the spacetime are obtained by using the counterterm method inspired by AdS/CFT correspondence. We derive temperature, electric potential and entropy associated with the horizon and check the validity of the first law of thermodynamics on the black brane horizon. We study thermal stability of the solutions in both canonical and grand canonical ensemble and disclose the effects of the rotation parameter, nonlinearity of electrodynamics and dilaton field on the thermal stability conditions. We find the solutions are thermally stable for $\\a...
Directory of Open Access Journals (Sweden)
A. Sheykhi
2016-01-01
Full Text Available We construct a new class of charged rotating black brane solutions in the presence of logarithmic nonlinear electrodynamics with complete set of the rotation parameters in arbitrary dimensions. The topology of the horizon of these rotating black branes is flat, while due to the presence of the dilaton field the asymptotic behavior of them is neither flat nor (anti-de Sitter [(AdS]. We investigate the physical properties of the solutions. The mass and angular momentum of the spacetime are obtained by using the counterterm method inspired by AdS/CFT correspondence. We derive temperature, electric potential, and entropy associated with the horizon and check the validity of the first law of thermodynamics on the black brane horizon. We study thermal stability of the solutions in both canonical and grand-canonical ensemble and disclose the effects of the rotation parameter, nonlinearity of electrodynamics, and dilaton field on the thermal stability conditions. We find the solutions are thermally stable for α1 the solutions may encounter an unstable phase, where α is dilaton-electromagnetic coupling constant.
Energy Technology Data Exchange (ETDEWEB)
Belmonte-Beitia, Juan [Departamento de Matematicas, E.T.S. de Ingenieros Industriales and Instituto de Matematica Aplicada a la Ciencia y la Ingenieria (IMACI), Avda. Camilo Jose Cela 3, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)], E-mail: juan.belmonte@uclm.es; Calvo, Gabriel F. [Departamento de Matematicas, E.T.S. de Ingenieros Industriales and Instituto de Matematica Aplicada a la Ciencia y la Ingenieria (IMACI), Avda. Camilo Jose Cela 3, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)], E-mail: gabriel.fernandez@uclm.es
2009-01-19
In this Letter, by means of similarity transformations, we construct explicit solutions to the quintic nonlinear Schroedinger equation with potentials and nonlinearities depending both on time and on the spatial coordinates. We present the general approach and use it to study some examples and find nontrivial explicit solutions such as periodic (breathers), quasiperiodic and bright and dark soliton solutions.
Origin of space-separated charges in photoexcited organic heterojunctions on ultrafast time scales
Janković, Veljko
2016-01-01
We present detailed investigation of ultrafast (sub-ps) exciton dynamics in the lattice model of a donor/acceptor heterojunction. Exciton generation by means of a photoexcitation, exciton dissociation, and further charge separation are treated on equal footing. The experimentally observed presence of space-separated charges at $\\lesssim 100$ fs after the photoexcitation is usually attributed to ultrafast transitions from excitons in the donor to charge transfer and charge separated states. Here, we show, however, that space-separated charges appearing on $\\lesssim 100$-fs time scales are predominantly directly optically generated. Our theoretical insights into the ultrafast pump-probe spectroscopy challenge usual interpretations of pump-probe spectra in terms of ultrafast population transfer from donor excitons to space-separated charges.
Space Charge Accumulation and Micro-Structure of Cross-linked Polyethylene
Li, Jixiao; Zhang, Yewen; Zheng, Feihu; Wu, Changshun
2004-12-01
In this paper, laser induced pressure pulse (LIPP) method and electrostatic force microscopy (EFM) method are utilized to investigate the distribution of space charge in cross-linked polyethylene (XLPE), and the action on the groups of XLPE by the accumulative charge are investigated by infrared spectroscopy (IR) method. It was found that space charge in the sample has obvious influence on the vibration of chemical group, especially on group OH, group CH3 and group CH2. Group vibration affected considerably by space charge in XLPE sample locates on the interface between crystalline and amorphous domains. The experimental results also indicate that positive charge compared to negative charge has a different effect on bands.
Dielectric process of space-charge polarization for an electrolytic cell with blocking electrodes.
Sawada, Atsushi
2008-08-14
The dielectric process of space-charge polarization for an electrolytic cell with blocking electrodes is simulated considering bound charges externally supplied to the electrodes. A numerical calculation is performed to determine the distribution of mobile charges under an ac field satisfying Poisson's equation in which the dielectric constant varies with frequency. An exact frequency-dependent curve of the complex dielectric constant is obtained by including the contribution of bound charges induced by the space-charge polarization itself in Poisson's equation at every frequency. The present model of the space-charge polarization enables one to correctly understand the experimental results on the complex dielectric constant of electrolytic cells in low-frequency regions.
Locally Bounded Function Spaces as the External Environment for Nonlinear Systems
Directory of Open Access Journals (Sweden)
Valery G. Fetisov
2013-01-01
Full Text Available . In this paper we consider locally bounded function spaces that act as the external environment for nonlinear dynamic systems. We give non-traditional examples of above spaces in which the basis of the selected function Orlicz space
Identification of Nonlinear Nonautonomous State Space Systems from Input-Output Measurements
Verdult, Vincent; Verhaegen, Michel; Scherpen, Jacquelien
2000-01-01
This paper presents a method to determine a nonlinear state space model from a finite number of measurements of the inputs and outputs. The method is based on embedding theory for nonlinear systems, and can be viewed as an extension of the subspace identification method for linear systems. The paper
Institute of Scientific and Technical Information of China (English)
Wan-sheng WANG; Shou-fu LI; Run-sheng YANG
2012-01-01
A series of contractivity and exponential stability results for the solutions to nonlinear neutral functional differential equations (NFDEs) in Banach spaces are obtained,which provide unified theoretical foundation for the contractivity analysis of solutions to nonlinear problems in functional differential equations (FDEs),neutral delay differential equations (NDDEs) and NFDEs of other types which appear in practice.
NONLOCAL INITIAL PROBLEM FOR NONLINEAR NONAUTONOMOUS DIFFERENTIAL EQUATIONS IN A BANACH SPACE
Institute of Scientific and Technical Information of China (English)
M.I.Gil＇
2004-01-01
The nonlocal initial problem for nonlinear nonautonomous evolution equations in a Banach space is considered. It is assumed that the nonlinearities have the local Lipschitz properties. The existence and uniqueness of mild solutions are proved. Applications to integro-differential equations are discussed. The main tool in the paper is the normalizing mapping (the generalized norm).
List, Nanna Holmgaard; Zaleśny, Robert; Murugan, N Arul; Kongsted, Jacob; Bartkowiak, Wojciech; Ågren, Hans
2015-09-08
We establish the relationships between the metric of charge transfer excitation (Δr) for the bright ππ* state and the two-photon absorption probability as well as the first hyperpolarizability for two families of push-pull π-conjugated systems. As previously demonstrated by Guido et al. (J. Chem. Theory Comput. 2013, 9, 3118-3126), Δr is a measure for the average hole-electron distance upon excitation and can be used to discriminate between short- and long-range electronic excitations. We indicate two new benefits from using this metric for the analyses of nonlinear optical properties of push-pull systems. First, the two-photon absorption probability and the first hyperpolarizability are found to be interrelated through Δr; if β ∼ (Δr)(k), then roughly, δ(TPA) ∼ (Δr)(k+1). Second, a simple power relation between Δr and the molecular hyperpolarizabilities of push-pull systems offers the possibility of estimating properties for longer molecular chains without performing calculations of high-order response functions explicitly. We further demonstrate how to link the hyperpolarizabilities with the chain length of the push-pull π-conjugated systems through the metric of charge transfer.
Oloff, L.-P.; Hanff, K.; Stange, A.; Rohde, G.; Diekmann, F.; Bauer, M.; Rossnagel, K.
2016-06-01
With the advent of ultrashort-pulsed extreme ultraviolet sources, such as free-electron lasers or high-harmonic-generation (HHG) sources, a new research field for photoelectron spectroscopy has opened up in terms of femtosecond time-resolved pump-probe experiments. The impact of the high peak brilliance of these novel sources on photoemission spectra, so-called vacuum space-charge effects caused by the Coulomb interaction among the photoemitted probe electrons, has been studied extensively. However, possible distortions of the energy and momentum distributions of the probe photoelectrons caused by the low photon energy pump pulse due to the nonlinear emission of electrons have not been studied in detail yet. Here, we systematically investigate these pump laser-induced space-charge effects in a HHG-based experiment for the test case of highly oriented pyrolytic graphite. Specifically, we determine how the key parameters of the pump pulse—the excitation density, wavelength, spot size, and emitted electron energy distribution—affect the measured time-dependent energy and momentum distributions of the probe photoelectrons. The results are well reproduced by a simple mean-field model, which could open a path for the correction of pump laser-induced space-charge effects and thus toward probing ultrafast electron dynamics in strongly excited materials.
Space Charge Characteristics of Oil-paper Insulation with New Paper and Aged Oil
Institute of Scientific and Technical Information of China (English)
MU Haibao; WANG Da; WANG Shiqiang; TIAN Jie; LI Yuan; WEI Yanhui; ZHANG Guanjun
2013-01-01
Oil-paper compound insulation has been widely used in power transformers for quite a long time because of its good performances.The insulation gradually degrades under combined thermal,electrical and chemical stresses during routine operations,mainly because of space charges inside.This work investigated the space charge characteristics in oil-paper insulation under oil aging circumstance.New transformer oil samples are thermally aged to obtain different aging states,and their physical and chemical properties are analyzed.New Kraft papers are dried in vacuum and fully immersed in these different aged oil samples,and three kinds of oil-paper samples are obtained.We use the pulsed electro-acoustic (PEA) method to measure space charge under both DC voltage-on and voltage-off conditions at room temperature.The effect ofoil aging state on characteristics of space charge injection,accumulation,and decay is analyzed and discussed.The results show that comparing with the DC voltage-off condition,more charges are injected into samples at the interface of electrode and dielectric when DC voltage is on.When the oil-aged state gets worse,more charges are induced at both cathode and anode,more space charges are accumulated in the bulk,the area of negative charges is larger,and local electric field is distorted more seriously.Moreover,for the voltage-off condition,aged oil is good for space charge decay,and trapped positive space charges decay faster than trapped negative charges.
Asymptotic Symmetries and Charges in De Sitter Space
Anninos, Dionysios; Strominger, Andrew
2010-01-01
The asymptotic symmetry group (ASG) at future null infinity (I^+) of four-dimensional de Sitter spacetimes is defined and shown to be given by the group of three-dimensional diffeomorphisms acting on I^+. Finite charges are constructed for each choice of ASG generator together with a two-surface on I^+. A conservation equation is derived relating the evolution of the charges with the radiation flux through I^+.
Asymptotic symmetries and charges in de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Anninos, Dionysios; Ng, Gim Seng; Strominger, Andrew, E-mail: gng@fas.harvard.edu [Center for the Fundamental Laws of Nature, Harvard University, Cambridge, MA 02138 (United States)
2011-09-07
The asymptotic symmetry group (ASG) at future null infinity (I{sup +}) of asymptotically four-dimensional de Sitter spacetimes is defined and shown to be given by the group of three-dimensional diffeomorphisms acting on I{sup +}. Finite charges are constructed for each choice of ASG generator together with a two-surface on I{sup +}. A conservation equation is derived relating the evolution of the charges with the radiation flux through I{sup +}.
Charge quantization and the Standard Model from the CP 2 and CP 3 nonlinear If-models
National Research Council Canada - National Science Library
Hellerman, Simeon; Kehayias, John; Yanagida, Tsutomu T
2014-01-01
We investigate charge quantization in the Standard Model (SM) through a CP.sup.2 nonlinear sigma model (NLSM), SU(3).sub.G/(SU(2).sub.HxU(1).sub.H), and a CP.sup.3 model, SU(4).sub.G/(SU(3).sub.HxU(1).sub.H...
Numeric description of space charge in polyethylene under ac electric fields
Zhao, J.; Xu, Z.; Chen, G.; Lewin, P. L.
2010-12-01
Space charge in polyethylene-based insulation materials and its effect on the local electric field under a dc environment have been extensively examined over the last few decades while the behavior of space charge under ac stress has received less attention. Space charge phenomenon under ac electric fields becomes an important issue with increased operating field strength in many applications, such as next generation high voltage cables. In this paper, a bipolar charge transport model has been developed to simulate space charge in polymers under ac electric fields. Obtained simulation results show that there is a small quantity of phase-dependent bipolar charge accumulation in the vicinity of the electrodes that does not move into the bulk under ac stress. This causes a slight distortion of the local field in the bulk. However, at lower frequencies less than 1 Hz, there is increased charge accumulation and penetration. Comparison with available experimental data suggests that the model is capable of describing the underlying physics of charge behavior when a dielectric material is subjected to ac electric fields. Due to the weak charge movement in the bulk, the conduction current density is small and hence the displacement component dominates the total current density and this increases linearly with ac frequency.
Simulation of Space Charge Dynamic in Polyethylene Under DC Continuous Electrical Stress
Boukhari, Hamed; Rogti, Fatiha
2016-10-01
The space charge dynamic plays a very important role in the aging and breakdown of polymeric insulation materials under high voltage. This is due to the intensification of the local electric field and the attendant chemical-mechanical effects in the vicinity around the trapped charge. In this paper, we have investigated the space charge dynamic in low-density polyethylene under high direct-current voltage, which is evaluated by experimental conditions. The evaluation is on the basis of simulation using a bipolar charge transport model consisting of charge injection, transports, trapping, detrapping, and recombination phenomena. The theoretical formulation of the physical problem is based on the Poisson, the continuity, and the transport equations. Numerical results provide temporal and local distributions of the electric field, the space charge density for the different kinds of charges (net charge density, mobile and trapped of electron density, mobile hole density), conduction and displacement current densities, and the external current. The result shows the appearance of the negative packet-like space charge with a large amount of the bulk under the dc electric field of 100 kV/mm, and the induced distortion of the electric field is largely near to the anode, about 39% higher than the initial electric field applied.
Space Charge Formation in XLPE - the Influence of Electrodes and Pre-conditioning
DEFF Research Database (Denmark)
Holbøll, Joachim T.; Henriksen, Mogens; Fleming, R.J.
1999-01-01
The composition of the inner and outer “semicon” shields in modern ac cables, and the temperature/pressure conditions under which the various manufacturing procedures are carried out, would be expected to influence space charge accumulation under dc stress significantly. However, few systematic...... investigations of the influence of these factors, on space charge accumulation or other electrical properties of XLPE, have been reported. In this paper we present space charge profiles for a range of XLPE planar samples under dc stress. Three different types of semicon electrodes were investigated, as well...
Self-Deflection of Dark Screening Spatial Solitons Based on Higher-Order Space Charge Field
Institute of Scientific and Technical Information of China (English)
ZHANG Guang-Yong; LIU Jin-Song; LIU Shi-Xiong; WANG Cheng; ZHANG Hui-Lan
2007-01-01
The effects of higher-order space charge field on the self-deflection of dark screening spatial solitons in biased photorefractive crystals are numerically investigated under steady-state conditions. The expression for an induced space-charge electric field including higher-order space-charge field terms is obtained. Numerical results indicate that dark solitons possess a self-deflection process during propagation, and the solitons always bend in the direction of the c axis of the crystal The self-deflection of dark solitons can experience considerable increase especially in the regime of high bias field strengths.
Space-charge-mediated anomalous ferroelectric switching in P(VDF-TrEE) polymer films
Hu, Weijin
2014-11-12
We report on the switching dynamics of P(VDF-TrEE) copolymer devices and the realization of additional substable ferroelectric states via modulation of the coupling between polarizations and space charges. The space-charge-limited current is revealed to be the dominant leakage mechanism in such organic ferroelectric devices, and electrostatic interactions due to space charges lead to the emergence of anomalous ferroelectric loops. The reliable control of ferroelectric switching in P(VDF-TrEE) copolymers opens doors toward engineering advanced organic memories with tailored switching characteristics.
Space Charge Compensation in the Linac4 Low Energy Beam Transport Line with Negative Hydrogen Ions
Valerio-Lizarraga, C; Leon-Monzon, I; Lettry, J; Midttun, O; Scrivens, R
2014-01-01
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Tranport (LEBT) using the package IBSimu1, which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H- beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
On Beam Matching and the Space-Charge Effect in protoDUNE-SP
Mandalia, Jesal Paresh
2017-01-01
In this project simulations using LArSoft have been analysed in particular looking at how the space-charge effect will affect the matching of particle tracks from the beam line monitor to the TPC and the TPC's performance measuring $\\frac{dE}{dx}$ in protoDUNE-SP. The analysis here provides some preliminary calibrations for protoDUNE-SP to account for the impact the space charge effect will have. Many areas of pion cross section analysis will be affected by the space charge effect so it is vital for a calibration to be developed.
Energy Technology Data Exchange (ETDEWEB)
Lund, S M; Kikuchi, T; Davidson, R C
2007-04-12
Self-consistent Vlasov simulations of beams with high space-charge intensity often require specification of initial phase-space distributions that reflect properties of a beam that is well adapted to the transport channel, both in terms of low-order rms (envelope) properties as well as the higher-order phase-space structure. Here, we first review broad classes of distributions commonly in use as initial Vlasov distributions in simulations of beams with intense space-charge fields including: the Kapchinskij-Vladimirskij (KV) equilibrium, continuous-focusing equilibria with specific detailed examples, and various non-equilibrium distributions, such as the semi-Gaussian distribution and distributions formed from specified functions of linear-field Courant-Snyder invariants. Important practical details necessary to specify these distributions in terms of usual accelerator inputs are presented in a unified format. Building on this presentation, a new class of approximate initial distributions are constructed using transformations that preserve linear-focusing single-particle Courant-Snyder invariants to map initial continuous-focusing equilibrium distributions to a form more appropriate for non-continuous focusing channels. Self-consistent particle-in-cell simulations are employed to show that the approximate initial distributions generated in this manner are better adapted to the focusing channels for beams with high space-charge intensity. This improved capability enables simulation applications that more precisely probe intrinsic stability properties and machine performance.
Energy Technology Data Exchange (ETDEWEB)
Lund, Steven M.; Kikuchi, Takashi; Davidson, Ronald C.
2007-04-03
Self-consistent Vlasov-Poisson simulations of beams with high space-charge intensity often require specification of initial phase-space distributions that reflect properties of a beam that is well adapted to the transport channel--both in terms of low-order rms (envelope) properties as well as the higher-order phase-space structure. Here, we first review broad classes of kinetic distributions commonly in use as initial Vlasov distributions in simulations of unbunched or weakly bunched beams with intense space-charge fields including: the Kapchinskij-Vladimirskij (KV) equilibrium, continuous-focusing equilibria with specific detailed examples, and various non-equilibrium distributions, such as the semi-Gaussian distribution and distributions formed from specified functions of linear-field Courant-Snyder invariants. Important practical details necessary to specify these distributions in terms of usual accelerator inputs are presented in a unified format. Building on this presentation, a new class of approximate initial kinetic distributions are constructed using transformations that preserve linear-focusing single-particle Courant-Snyder invariants to map initial continuous-focusing equilibrium distributions to a form more appropriate for non-continuous focusing channels. Self-consistent particle-in-cell simulations are employed to show that the approximate initial distributions generated in this manner are better adapted to the focusing channels for beams with high space-charge intensity. This improved capability enables simulation applications that more precisely probe intrinsic stability properties and machine performance.
Seljak, Uros
2012-01-01
On large scales a nonlinear transformation of matter density field can be viewed as a biased tracer of the density field itself. A nonlinear transformation also modifies the redshift space distortions in the same limit, giving rise to a velocity bias. In models with primordial nongaussianity a nonlinear transformation generates a scale dependent bias on large scales. We derive analytic expressions for these for a general nonlinear transformation. These biases can be expressed entirely in terms of the one point distribution function (PDF) of the final field and the parameters of the transformation. Our analysis allows one to devise nonlinear transformations with nearly arbitrary bias properties, which can be used to increase the signal in the large scale clustering limit. We apply the results to the ionizing equilibrium model of Lyman-alpha forest, in which Lyman-alpha flux F is related to the density perturbation delta via a nonlinear transformation. Velocity bias can be expressed as an average over the Lyman...
Energy Technology Data Exchange (ETDEWEB)
Noll, Daniel [Goethe Univ., Frankfurt (Germany); Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2015-11-17
An electron lens is planned for the Fermilab Integrable Optics Test Accelerator as a nonlinear element for integrable dynamics, as an electron cooler, and as an electron trap to study space-charge compensation in rings. We present the main design principles and constraints for nonlinear integrable optics. A magnetic configuration of the solenoids and of the toroidal section is laid out. Singleparticle tracking is used to optimize the electron path. Electron beam dynamics at high intensity is calculated with a particle-in-cell code to estimate current limits, profile distortions, and the effects on the circulating beam. In the conclusions, we summarize the main findings and list directions for further work.
Difference schemes for fully nonlinear pseudo-parabolic systems with two space dimensions
Institute of Scientific and Technical Information of China (English)
周毓麟; 袁光伟
1996-01-01
The first boundary value problem for the fully nonlinear pseudoparabolic systems of partial differential equations with two space dimensions by the finite difference method is studied. The existence and uniqueness of the discrete vector solutions for the difference systems are established by the fixed point technique. The stability and convergence of the discrete vector solutions of the difference schemes to the vector solutions of the original boundary problem of the fully nonlinear pseudo-parabolic system are obtained by way of a priori estimation. Here the unique smooth vector solution of the original problems for the fully nonlinear pseudo-parabolic system is assumed. Moreover, by the method used here, it can be proved that analogous results hold for fully nonlinear pseudo-parabolic system with three space dimensions, and improve the known results in the case of one space dimension.
Directory of Open Access Journals (Sweden)
Ronald C. Davidson
2015-09-01
Full Text Available This paper makes use of a one-dimensional kinetic model to investigate the nonlinear longitudinal dynamics of a long coasting beam propagating through a perfectly conducting circular pipe with radius r_{w}. The average axial electric field is expressed as ⟨E_{z}⟩=-(∂/∂z⟨ϕ⟩=-e_{b}g_{0}∂λ_{b}/∂z-e_{b}g_{2}r_{w}^{2}∂^{3}λ_{b}/∂z^{3}, where g_{0} and g_{2} are constant geometric factors, λ_{b}(z,t=∫dp_{z}F_{b}(z,p_{z},t is the line density of beam particles, and F_{b}(z,p_{z},t satisfies the 1D Vlasov equation. Detailed nonlinear properties of traveling-wave and traveling-pulse (soliton solutions with time-stationary waveform are examined for a wide range of system parameters extending from moderate-amplitudes to large-amplitude modulations of the beam charge density. Two classes of solutions for the beam distribution function are considered, corresponding to: (i the nonlinear waterbag distribution, where F_{b}=const in a bounded region of p_{z}-space; and (ii nonlinear Bernstein-Green-Kruskal (BGK-like solutions, allowing for both trapped and untrapped particle distributions to interact with the self-generated electric field ⟨E_{z}⟩.
Orbit-Attitude Changes of Objects in Near Earth Space Induced by Natural Charging
2017-05-02
COVERED (From - To) 21-05-2015 – 21-02-2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Orbit- Attitude Changes of Objects in Near Earth Space Induced...charging plasma conditions lead to significant secular perturbations in the investigated cases. 15. SUBJECT TERMS State-of-the Art; Attitude ...non-equilibrium scenario, charging takes place according to the differential equation, ∑ j I j = C dφdt . The time scale for charging of a spherical
On a state space approach to nonlinear H∞ control
Schaft, van der A.J.
1991-01-01
We study the standard H∞ optimal control problem using state feedback for smooth nonlinear control systems. The main theorem obtained roughly states that the L2-induced norm (from disturbances to inputs and outputs) can be made smaller than a constant γ > 0 if the corresponding H∞ norm for the syste
DEFF Research Database (Denmark)
Vogel, Stephan; Lopez, Javier; Holbøll, Joachim;
2015-01-01
that the effectof the removal of the corona space charge by the wind leadsto a higher field strength at the grounded object and, therefore,it becomes easier for it to initiate an upward connecting leadercompared to a situation where the space charge is present. Inthis work, a simplified space charge drift model...
Cousineau, Sarah M
2005-01-01
Space charge effects are a major contributor to beam halo and emittance growth leading to beam loss in high intensity, low energy accelerators. As future accelerators strive towards unprecedented levels of beam intensity and beam loss control, a more comprehensive understanding of space charge effects is required. A wealth of simulation tools have been developed for modeling beams in linacs and rings, and with the growing availability of high-speed computing systems, computationally expensive problems that were inconceivable a decade ago are now being handled with relative ease. This has opened the field for realistic simulations of space charge effects, including detailed benchmarks with experimental data. A great deal of effort is being focused in this direction, and several recent benchmark studies have produced remarkably successful results. This paper reviews the achievements in space charge benchmarking in the last few years, and discusses the challenges that remain.
Energy Technology Data Exchange (ETDEWEB)
Gallot-Lavallee, O [Laboratoire de Genie Electrique de Toulouse, Universite Paul Sabatier-118, Route de Narbonne, Toulouse 31062 (France); Teyssedre, G [Laboratoire de Genie Electrique de Toulouse, Universite Paul Sabatier-118, Route de Narbonne, Toulouse 31062 (France); Laurent, C [Laboratoire de Genie Electrique de Toulouse, Universite Paul Sabatier-118, Route de Narbonne, Toulouse 31062 (France); Rowe, S [Direction des Recherches Materiaux, Schneider Electric SA-20, Rue Henri Tarze, Grenoble 38050 (France)
2005-06-21
This study aims to characterize the behaviour of the space charge in an epoxy resin used as electrical insulation in systems such as transformers and bus bars. Temperature, field level, filler content and nature of the electrodes are the parameters that were considered. Space charge measurements were performed using the pulsed electro acoustic technique, in a range of field and temperature up to 40 kV mm{sup -1} and 72 deg. C, respectively, on gold-coated and un-coated samples. We discuss the possibility of performing space charge measurement on filled epoxy resin despite the piezoelectricity of quartz fillers. Under dc field we observed a quasi-symmetrical build-up of homocharges at both electrodes, followed by a substitution of the homocharges by heterocharges, mainly close to the cathode. In addition, we recorded the space charge behaviour just before breakdown on a filled sample at 72 deg. C under 12 kV mm{sup -1}.
Extreme Space Weather Events and Charging Hazard Assessments in Lunar Environments
Minow, Joseph I.; Parker, Linda N.; Blackwell, William C., Jr.
2008-01-01
The sunlit lunar surface charges to positive potentials with mean values of a few tens of volts where photoelectron currents dominate the charging process. In contrast, surfaces in darkness may charge to negative potentials on the order of a few hundred volts when the charging process is dominated by hot electron populations in the absence of solar photons. Recently, observations of electron beams measured by instruments on spacecraft in low lunar orbit have been interpreted as evidence for extreme lunar surface potentials exceeding a few kilovolts suggesting that lunar orbital and surface plasma environments may contain charging risks similar to geostationary orbit during extreme space weather conditions. Space system design for successful operation in a wide range of lunar environments will therefore require evaluation of charging hazards during extreme space weather conditions. We present results from a study of space weather environments conducted to obtained credible extreme charging environments for use in charging hazard assessments for lunar missions including extreme conditions encountered when the Moon is in the solar wind, the magnetosheath, and the Earth's magnetotail.
Breakdown and space charge formation in polyimide film under DC high stress at various temperatures
Energy Technology Data Exchange (ETDEWEB)
Kishi, Y; Hashimoto, T; Miyake, H; Tanaka, Y; Takada, T, E-mail: ytanaka@tcu.ac.j [Tokyo City University, 1-28-1, Tamatsutsumi, Setagaya-ku, Tokyo (Japan)
2009-08-01
Relationship between breakdown strength and space charge formation in polyimide film under dc high stress at various temperatures is investigated using pulsed electro-acoustic (PEA) method. Some typical results of the space charge observations show that hetero space charges are always found before breakdown. The amount of the hetero charges increase with increase of temperature or increase of applied electric field. Since the enhancement of the internal electric field in the sample by the accumulation of the hetero charges is not so large, the accumulation doesn't seem to be an immediate cause of breakdown. However since it is always observed before breakdown, it may be predictive information for breakdown. In a certain case, the breakdown occurs after voltage application for few hours. However, while we give an interval of short circuit condition after observing the hetero space charge under dc stress, the total voltage application time to breakdown is almost the same to the case without the interval. It means that the hetero space charge generation may show a kind of degradation of the material.
EFFECT OF SPACE CHARGE ON STABILITY OF BEAM DISTRIBUTION IN THE SNS RING.
Energy Technology Data Exchange (ETDEWEB)
FEDOTOV, A.V.; WEI, J.; GLUCKSTERN, R.L.
2001-06-18
In the Spallation Neutron Source (SNS) ring, multi-turn injection is employed to obtain a large transverse beam size which significantly reduces the space-charge tune shift of the accumulated beam. Careful choice of the painting scheme and bump function is required to obtain the desired beam profile together with low beam loss. In this paper we examine, both analytically and numerically, the effect of the space charge on the beam profile during multi-turn injection painting.
In-Situ Space Charge Measurements on Dielectrics during Electronic Irradiation by PEA
Nguyen, Xuan Truong; Griseri, V.; Berquez, L.
2013-01-01
International audience; Material used is space environment are submitted to a large amount of charged particles. This work is focused on the effect of electrons on PolytetraFluoroEthylene (PTFE) that is commonly found in satellites pieces of equipment. To study the behavior of electrons during and post-irradiation we are mainly using the Pulse Electro Acoustic (PEA) technique in an open configuration. Measurements are performed between two periods of irradiation under vacuum. The space charge...
Space Charge Simulations in the Fermilab Recycler for PIP-II
Energy Technology Data Exchange (ETDEWEB)
Ainsworth, Robert [Fermilab; Adamson, Philip [Fermilab; Kourbanis, Ioanis [Fermilab; Stern, Eric [Fermilab
2016-06-01
Proton Improvement Plan-II (PIP-II) is Fermilab's plan for providing powerful, high-intensity proton beams to the laboratory's experiments. Upgrades are foreseen for the recycler which will cope with bunches containing fifty percent more beam. Of particular concern is large space charge tune shifts caused by the intensity increase. Simulations performed using Synergia are detailed focusing on the space charge footprint.
Directory of Open Access Journals (Sweden)
Stefan Paret
2010-02-01
Full Text Available Transverse Schottky spectra and beam transfer functions (BTFs of coasting ion beams were measured in the heavy ion synchrotron SIS-18 in order to study the impact of space charge on the transverse beam dynamics. The particle number in the beam was varied to investigate the intensity dependence of the space-charge effect. No cooling was applied to the beams throughout the experiment. The expected deformation of the Schottky spectra and BTFs is observed. An analytic model with linear space charge is employed to describe the deformed Schottky and BTF signals. In this model, the incoherent space-charge force and the coherent forces due to impedances are treated separately. Using the model, the space-charge induced tune shift is evaluated both from the position and the form of the signals. The data are well described by the model, only in the high-intensity BTFs deviations are observed. The stability diagrams are shifted according to the space-charge parameter obtained from the BTFs. In addition, the tune shift is estimated by virtue of measured beam profiles and particle numbers. The estimated tune shift is of the same order of magnitude but smaller than the measured one. Possible explanations for deviations between the measurements, the model, and the estimation are discussed.
Space-charge-dominated mass spectrometry ion sources: Modeling and sensitivity.
Busman, M; Sunner, J; Vogel, C R
1991-01-01
The factors determining the sensitivity of space-charge-dominated (SCD) unipolar ion sources, such as electrospray (ESP) and corona atmospheric pressure ionization (API) have been studied theoretically. The most important parameters are the ion density and ion drift time in the vicinity of the sampling orifice. These are obtained by solving a system of differential equations, "the space-charge problem." For some simple geometries, analytical solutions are known. For a more realistic "needle-in-can" geometry, a solution to the space-charge problem was obtained using a finite-element method. The results illustrate some general characteristics of SCD ion sources. It is shown that for typical operating conditions the minimum voltage required to overcome the space-charge effect in corona API or ESP ion sources constitutes a dominant or significant fraction of total applied voltage. Further, the electric field and the ion density in the region of the ion-sampling orifice as well as the ion residence time in the source are determined mainly by the space charge. Finally, absolute sensitivities of corona API ion sources were calculated by using a geometry-independent treatment of space charge.
Jet physics from static charges in AdS space
Chien, Yang-Ting; Schwartz, Matthew D.; Simmons-Duffin, David; Stewart, Iain W.
2012-02-01
Soft interactions with high-energy jets are explored in radial coordinates which exploit the approximately conformal behavior of perturbative gauge theories. In these coordinates, the jets, approximated by Wilson lines, become static charges in Euclidean AdS. The anomalous dimension of the corresponding Wilson line operator is then determined by the potential energy of the charges. To study these Wilson lines we introduce a “conformal gauge” which does not have kinetic mixing between radial and angular directions, and show that a number of properties of Wilson lines are reproduced through relatively simple calculations. For example, certain nonplanar graphs involving multiple Wilson lines automatically vanish. We also discuss the linear growth of the charges’ imaginary potential energy with separation, and a relationship between Wilson line diagrams and Witten diagrams.
Directory of Open Access Journals (Sweden)
Banan Maayah
2014-01-01
Full Text Available A new algorithm called multistep reproducing kernel Hilbert space method is represented to solve nonlinear oscillator’s models. The proposed scheme is a modification of the reproducing kernel Hilbert space method, which will increase the intervals of convergence for the series solution. The numerical results demonstrate the validity and the applicability of the new technique. A very good agreement was found between the results obtained using the presented algorithm and the Runge-Kutta method, which shows that the multistep reproducing kernel Hilbert space method is very efficient and convenient for solving nonlinear oscillator’s models.
Geometry and quadratic nonlinearity of charge transfer complexes in solution: a theoretical study.
Mukhopadhyay, S; Pandey, Ravindra; Das, Puspendu K; Ramasesha, S
2011-01-28
In this paper, we have computed the quadratic nonlinear optical (NLO) properties of a class of weak charge transfer (CT) complexes. These weak complexes are formed when the methyl substituted benzenes (donors) are added to strong acceptors like chloranil (CHL) or di-chloro-di-cyano benzoquinone (DDQ) in chloroform or in dichloromethane. The formation of such complexes is manifested by the presence of a broad absorption maximum in the visible range of the spectrum where neither the donor nor the acceptor absorbs. The appearance of this visible band is due to CT interactions, which result in strong NLO responses. We have employed the semiempirical intermediate neglect of differential overlap (INDO∕S) Hamiltonian to calculate the energy levels of these CT complexes using single and double configuration interaction (SDCI). The solvent effects are taken into account by using the self-consistent reaction field (SCRF) scheme. The geometry of the complex is obtained by exploring different relative molecular geometries by rotating the acceptor with respect to the fixed donor about three different axes. The theoretical geometry that best fits the experimental energy gaps, β(HRS) and macroscopic depolarization ratios is taken to be the most probable geometry of the complex. Our studies show that the most probable geometry of these complexes in solution is the parallel displaced structure with a significant twist in some cases.
Energy Technology Data Exchange (ETDEWEB)
Herrera-Aguilar, Alfredo [Instituto de FIsica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio C-3, Ciudad Universitaria, Morelia, Mich., CP 58040 (Mexico); Nowakowski, Marek [Departamento de FIsica, Universidad de los Andes, Cra. 1 No 18A-10, Santa Fe de Bogota (Colombia)
2004-02-21
Using the stationary formulation of the toroidally compactified heterotic string theory in terms of a pair of matrix Ernst potentials we consider the four-dimensional truncation of this theory with no U(1) vector fields excited. Imposing one timelike Killing vector permits us to express the stationary effective action as a model in which gravity is coupled to a matrix Ernst potential which, under certain parametrization, allows us to interpret the matter sector of this theory as a double Ernst system. We generate a web of string vacua which are related to each other via a set of discrete symmetries of the effective action (some of them involve S-duality transformations and possess non-perturbative character). Some physical implications of these discrete symmetries are analysed and we find that, in some particular cases, they relate rotating black holes coupled to a dilaton with no Kalb-Ramond field, static black holes with non-trivial dilaton and antisymmetric tensor fields, and rotating and static naked singularities. Further, by applying a nonlinear symmetry, namely, the so-called normalized Harrison transformation, on the seed field configurations corresponding to these neutral backgrounds, we recover the U(1){sup n} Abelian vector sector of the four-dimensional action of the heterotic string, charging in this way the double Ernst system which corresponds to each one of the neutral string vacua, i.e., the stationary and the static black holes and the naked singularities.
Leech Lattice Extension of the Non-linear Schrodinger Equation Theory of Einstein spaces
Chapline, George
2015-01-01
Although the nonlinear Schrodinger equation description of Einstein spaces has provided insights into how quantum mechanics might modify the classical general relativistic description of space-time, an exact quantum description of space-times with matter has remained elusive. In this note we outline how the nonlinear Schrodinger equation theory of Einstein spaces might be generalized to include matter by transplanting the theory to the 25+1 dimensional Lorentzian Leech lattice. Remarkably when a hexagonal section of the Leech lattice is set aside as the stage for the nonlinear Schrodinger equation, the discrete automorphism group of the complex Leech lattice with one complex direction fixed can be lifted to continuous Lie group symmetries. In this setting the wave function becomes an 11x11 complex matrix which represents matter degrees of freedom consisting of a 2-form abelian gauge field and vector nonabelian SU(3)xE6 gauge fields together with their supersymmetric partners. The lagrangian field equations fo...
Metal nanoparticle mediated space charge and its optical control in an organic hole-only device
Energy Technology Data Exchange (ETDEWEB)
Ligorio, G.; Nardi, M. V. [Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor Str. 6, 12489 Berlin (Germany); Steyrleuthner, R.; Neher, D. [Institute of Physics and Astronomy, Universität Potsdam, Karl-Liebknecht Str. 24, 14476 Potsdam (Germany); Ihiawakrim, D. [Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, 67034 Strasbourg, Cedex2 (France); Crespo-Monteiro, N.; Brinkmann, M. [Institut Charles Sadron CNRS, 23 rue du Loess, 67034 Strasbourg (France); Koch, N., E-mail: norbert.koch@physik.hu-berlin.de [Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor Str. 6, 12489 Berlin (Germany); Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Erneuerbare Energien, Albert-Einstein Str. 15, 12489 Berlin (Germany)
2016-04-11
We reveal the role of localized space charges in hole-only devices based on an organic semiconductor with embedded metal nanoparticles (MNPs). MNPs act as deep traps for holes and reduce the current density compared to a device without MNPs by a factor of 10{sup 4} due to the build-up of localized space charge. Dynamic MNPs charged neutrality can be realized during operation by electron transfer from excitons created in the organic matrix, enabling light sensing independent of device bias. In contrast to the previous speculations, electrical bistability in such devices was not observed.
The Influence of Pre-Conditioning on Space Charge Formation in LDPE
DEFF Research Database (Denmark)
Fleming, Robert J.; Henriksen, Mogens; Holbøll, Joachim T.
1996-01-01
In this paper we present space charge accumulation data for planar low density polyethylene samples subjected to 20 kV/mm dc fields at room temperature. The data were obtained using the laser-induced-pressure-pulse (LIPP) technique. Some of the samples were conditioned by holding them at 40oC in ......C in short-circuit at rotary pump pressure for 48 hr prior to measurement. Such conditioning had no consistent effect on the space charge. The extent of charge injection/extraction at the semicon electrodes appeared to vary considerably between samples....
Schiffbauer, Jarrod; Liel, Uri; Leibowitz, Neta; Park, Sinwook; Yossifon, Gilad
2015-07-01
We present results demonstrating the space charge-mediated transition between classical, diffusion-limited current and surface-conduction dominant over-limiting current in a shallow microchannel-nanochannel device. The extended space charge layer develops at the depleted microchannel-nanochannel entrance at high current and is correlated with a distinctive maximum in the dc resistance. Experimental results for a shallow surface-conduction dominated system are compared with theoretical models, allowing estimates of the effective surface charge at high voltage to be obtained. In comparison to an equilibrium estimate of the surface charge obtained from electrochemical impedance spectroscopy, it is further observed that the effective surface charge appears to change under applied voltage.
Space-charge impedance of rf-shielding wires with external ceramic and conducting pipes
Wang, Tai-Sen F.; Kurennoy, Sergey S.; Gluckstern, Robert L.
2001-10-01
We studied the electrostatic field due to a charged-particle beam with uniform particle density propagating inside an rf-shielding cage (rf cage) constructed from evenly spaced conducting wires. The beam and the rf cage are surrounded by a ceramic beam pipe positioned inside a conducting pipe concentric with the beam and the rf cage. The space-charge impedances in the long wavelength regime are investigated by considering the electrostatic fields due to the longitudinal and transverse perturbations on the density of the charged-particle beam. Shielding effects due to the rf cage are discussed and simple formulas are derived for estimating the space-charge impedances. Numerical examples are given for illustration. Comparisons between analytical estimates and the results produced by the field-solver computer program MAFIA show good agreement.
Extended phase space of Black Holes in Lovelock gravity with nonlinear electrodynamics
Hendi, S H; Panah, B Eslam
2015-01-01
In this paper, we consider Lovelock gravity in presence of two Born-Infeld types of nonlinear electrodynamics and study their thermodynamical behavior. We extend the phase space by considering cosmological constant as a thermodynamical pressure. We obtain critical values of pressure, volume and temperature and investigate the effects of both the Lovelock gravity and the nonlinear electrodynamics on these values. We plot $P-v$, $T-v$ and $G-T$ diagrams to study the phase transition of these thermodynamical systems. We show that power of the nonlinearity and gravity have opposite effects. We also show how considering cosmological constant, nonlinearity and Lovelock parameters as thermodynamical variables will modify Smarr formula and first law of thermodynamics. In addition, we study the behavior of universal ratio of $\\frac{P_{c}v_{c}}{T_{c}}$ for different values of nonlinearity power of electrodynamics as well as the Lovelock coefficients.
Variational space-time (dis)continuous Galerkin method for nonlinear free surface waves
Gagarina, E; Vegt, van der, N.F.A.; Ambati, V.R.; Bokhove, O.
2013-01-01
A new variational finite element method is developed for nonlinear free surface gravity water waves. This method also handles waves generated by a wave maker. Its formulation stems from Miles' variational principle for water waves together with a space-time finite element discretization that is continuous in space and discontinuous in time. The key features of this formulation are: (i) a discrete variational approach that gives rise to conservation of discrete energy and phase space and prese...
Collective instabilities and collisional effects for space charge dominated beams
Energy Technology Data Exchange (ETDEWEB)
Benedetti, C. [Dipartimento di Fisica, Universita di Bologna and INFN, Via Irnerio 46, 40126 Bologna (Italy)]. E-mail: benedetti@bo.infn.it; Turchetti, G. [Dipartimento di Fisica, Universita di Bologna and INFN, Via Irnerio 46, 40126 Bologna (Italy)
2007-07-01
This paper is organized into two parts. In the first one we analyze the equipartitioning process in the presence of collisions for a Gaussian anisotropic beam. Far from instabilities the equipartition process can be described correctly by using Landau's collisional theory, whereas when the dynamics of the system is strongly nonlinear (e.g. in the vicinity of a resonance) a hybrid dynamical-collisional equipartition mechanism occurs. In the second part of the paper we discuss shortly a systematic study of the collective instabilities in a symmetric periodic focusing channel for a KV beam by using the moments method. We emphasize differences occurring when the periodic focusing lattice is replaced by the corresponding constant focusing one.
Charged dust phenomena in the near-Earth space environment
Scales, W. A.; Mahmoudian, A.
2016-10-01
Dusty (or complex) plasmas in the Earth’s middle and upper atmosphere ultimately result in exotic phenomena that are currently forefront research issues in the space science community. This paper presents some of the basic criteria and fundamental physical processes associated with the creation, evolution and dynamics of dusty plasmas in the near-Earth space environment. Recent remote sensing techniques to probe naturally created dusty plasma regions are also discussed. These include ground-based experiments employing high-power radio wave interaction. Some characteristics of the dusty plasmas that are actively produced by space-borne aerosol release experiments are discussed. Basic models that may be used to investigate the characteristics of such dusty plasma regions are presented.
Institute of Scientific and Technical Information of China (English)
LI Shoufu
2005-01-01
A series of stability, contractivity and asymptotic stability results of the solutions to nonlinear stiff Volterra functional differential equations (VFDEs) in Banach spaces is obtained, which provides the unified theoretical foundation for the stability analysis of solutions to nonlinear stiff problems in ordinary differential equations(ODEs), delay differential equations(DDEs), integro-differential equations(IDEs) and VFDEs of other type which appear in practice.
MCMC for non-linear state space models using ensembles of latent sequences
2013-01-01
Non-linear state space models are a widely-used class of models for biological, economic, and physical processes. Fitting these models to observed data is a difficult inference problem that has no straightforward solution. We take a Bayesian approach to the inference of unknown parameters of a non-linear state model; this, in turn, requires the availability of efficient Markov Chain Monte Carlo (MCMC) sampling methods for the latent (hidden) variables and model parameters. Using the ensemble ...
Dijkstra, Arend G
2015-01-01
We study hole, electron and exciton transport in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole and exciton transfer can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states du...
Energy Technology Data Exchange (ETDEWEB)
Alvarez-Estrada, R.F.
1979-08-01
A comprehensive review of the inverse scattering solution of certain non-linear evolution equations of physical interest in one space dimension is presented. We explain in some detail the interrelated techniques which allow to linearize exactly the following equations: (1) the Korteweg and de Vries equation; (2) the non-linear Schrodinger equation; (3) the modified Korteweg and de Vries equation; (4) the Sine-Gordon equation. We concentrate in discussing the pairs of linear operators which accomplish such an exact linearization and the solution of the associated initial value problem. The application of the method to other non-linear evolution equations is reviewed very briefly.
ANTI-PERIODIC SOLUTIONS FOR FIRST AND SECOND ORDER NONLINEAR EVOLUTION EQUATIONS IN BANACH SPACES
Institute of Scientific and Technical Information of China (English)
WEI Wei; XIANG Xiaoling
2004-01-01
In this paper, a new existence theorem of anti-periodic solutions for a class ofstrongly nonlinear evolution equations in Banach spaces is presentedThe equations con-tain nonlinear monotone operators and a nonmonotone perturbationMoreover, throughan appropriate transformation, the existence of anti-periodic solutions for a class of second-order nonlinear evolution equations is verifiedOur abstract results are illustrated by anexample from quasi-linear partial differential equations with time anti-periodic conditionsand an example from quasi-linear anti-periodic hyperbolic differential equations.
Simulating Nonlinear Dynamics of Deployable Space Structures Project
National Aeronautics and Space Administration — To support NASA's vital interest in developing much larger solar array structures over the next 20 years, MotionPort LLC's Phase I SBIR project will strengthen...
Spacecraft charging and plasma interaction implications for large space systems
Miller, E.; Stauber, M.; Rossi, M.; Fischbein, W.
1978-01-01
Specific discharge mechanisms, plasma interactions, and scale effects associated with very large spacecraft are studied. The large area, low density character, and extensive use of non-conducting materials is thought to have a major impact on the performance and survivability of many large space systems.
Energy Technology Data Exchange (ETDEWEB)
Sushkov, V.V. E-mail: vvsouchkov@lbl.gov
2000-08-01
Differential non-linearity (DNL) compensation in an analog-to-digital converter (ADC) is discussed. The successive approximation ADC under study employs charge redistribution in an array of binary weighted capacitors. The method of DNL compensation is supposed to be implemented in the ADC destined for the tracker readout of the CMS detector at LHC. The parameters of the DNL compensation technique are treated with the constructed simulator built in the Mathematica programming environment.
Sushkov, V V
2000-01-01
Differential non-linearity (DNL) compensation in an analog-to-digital converter (ADC) is discussed. The successive approximation ADC under study employs charge redistribution in an array of binary weighted capacitors. The method of DNL compensation is supposed to be implemented in the ADC destined for the tracker readout of the CMS detector at LHC. The parameters of the DNL compensation technique are treated with the constructed simulator built in the Mathematica programming environment. (4 refs).
Elsaesser, Thomas; Reimann, Klaus; Woerner, Michael
2015-06-01
Intense terahertz (THz) electric field transients with amplitudes up to several megavolts/centimeter and novel multidimensional techniques are the key ingredients of nonlinear THz spectroscopy, a new area of basic research. Both nonlinear light-matter interactions including the non-perturbative regime and THz driven charge transport give new insight into the character and dynamics of low-energy excitations of condensed matter and into quantum kinetic phenomena. This article provides an overview of recent progress in this field, combining an account of technological developments with selected prototype results for liquids and solids. The potential of nonlinear THz methods for future studies of low-frequency excitations of condensed-phase molecular systems is discussed as well.
Energy Technology Data Exchange (ETDEWEB)
El-Hanbaly, A. M.; Sallah, M., E-mail: msallahd@mans.edu.eg [Mansoura University, Physics Department, Faculty of Science (Egypt); El-Shewy, E. K. [Taibah University Al-Madinah Al-Munawarah, Department of Physics (Saudi Arabia); Darweesh, H. F. [Mansoura University, Physics Department, Faculty of Science (Egypt)
2015-10-15
Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions are related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems.
The influence of oxidation on space charge formation in gamma-irradiated low-density polyethylene
Chen, G; Xie, H K; Banford, H M; Davies, A E
2003-01-01
The research presented in this paper investigates the role of oxidation in the formation of space charge in gamma-irradiated low-density polyethylene after being electrically stressed under dc voltage. Polyethylene plaques both with and without antioxidant were irradiated up to 500 kGy using a sup 6 sup 0 Co gamma source and space charge distributions were measured using the piezoelectric induced pressure wave propagation method. It has been found that a large amount of positive charge evolved adjacent to the cathode in the sample without antioxidant and was clearly associated with oxidation of the surface. The amount of charge formed for a given applied stress increased with the dose absorbed by the material. A model has been proposed to explain the formation of space charge and its profile. The charge decay after the removal of the external applied stress is dominated by a process being controlled by the cathode interfacial stress (charge injection) rather than a conventional RC circuit model. On the other ...
Space Weather Impacts on Spacecraft Design and Operations in Auroral Charging Environments
Minow, Joseph I.; Parker, Linda N.
2012-01-01
Spacecraft in low altitude, high inclination (including sun-synchronous) orbits are widely used for remote sensing of the Earth s land surface and oceans, monitoring weather and climate, communications, scientific studies of the upper atmosphere and ionosphere, and a variety of other scientific, commercial, and military applications. These systems are episodically exposed to environments characterized by a high flux of energetic (approx.1 to 10 s kilovolt) electrons in regions of very low background plasma density which is similar in some ways to the space weather conditions in geostationary orbit responsible for spacecraft charging to kilovolt levels. While it is well established that charging conditions in geostationary orbit are responsible for many anomalies and even spacecraft failures, to date there have been relatively few such reports due to charging in auroral environments. This presentation first reviews the physics of the space environment and its interactions with spacecraft materials that control auroral charging rates and the anticipated maximum potentials that should be observed on spacecraft surfaces during disturbed space weather conditions. We then describe how the theoretical values compare to the observational history of extreme charging in auroral environments and discuss how space weather impacts both spacecraft design and operations for vehicles on orbital trajectories that traverse auroral charging environments.
EBQ code: transport of space-charge beams in axially symmetric devices
Energy Technology Data Exchange (ETDEWEB)
Paul, A.C.
1982-11-01
Such general-purpose space charge codes as EGUN, BATES, WOLF, and TRANSPORT do not gracefully accommodate the simulation of relativistic space-charged beams propagating a long distance in axially symmetric devices where a high degree of cancellation has occurred between the self-magnetic and self-electric forces of the beam. The EBQ code was written specifically to follow high current beam particles where space charge is important in long distance flight in axially symmetric machines possessing external electric and magnetic field. EBQ simultaneously tracks all trajectories so as to allow procedures for charge deposition based on inter-ray separations. The orbits are treated in Cartesian geometry (position and momentum) with z as the independent variable. Poisson's equation is solved in cylindrical geometry on an orthogonal rectangular mesh. EBQ can also handle problems involving multiple ion species where the space charge from each must be included. Such problems arise in the design of ion sources where different charge and mass states are present.
Charging of Space Debris and Their Dynamical Consequences
2016-01-08
and Plasma Physics Group, Department of Astronomy ...senabhijit@gmail.com 1DISTRIBUTION A: Distribution approved for public release. I. INTRODUCTION The near exponential rise of space debris at the...hamr) objects: influence of solar radiation pressure, earths shadow and the visibility in light curves. Celestial Mechanics and Dynamical Astronomy
Nonlinear Approximation and the Space BV(R2)
1997-01-01
number t let Uf t infgBVQ kf gk LI tVQg where the inmum is taken over all functions g BV of bounded variation on I This and related...all functions g BV of bounded variation on I This and related extremal problems arise in several areas of mathematics such as interpolation of...Q tVQg Here BVQ is the space of functions of bounded variation on Q see x for the de nition of this space and VQf jf jBV is the
Energy Technology Data Exchange (ETDEWEB)
Subalakshmi, R. [Department of Mathematics, Bharathiar University, Coimbatore 641 046 (India)], E-mail: suba.ab.bu@gmail.com; Balachandran, K. [Department of Mathematics, Bharathiar University, Coimbatore 641 046 (India)], E-mail: balachandran_k@lycos.com
2009-11-30
Many practical systems in physical and biological sciences have impulsive dynamical behaviours during the evolution process which can be modeled by impulsive differential equations. This paper studies the approximate controllability properties of nonlinear stochastic impulsive integrodifferential and neutral functional stochastic impulsive integrodifferential equations in Hilbert spaces. Assuming the conditions for the approximate controllability of these linear systems we obtain the sufficient conditions for the approximate controllability of these associated nonlinear stochastic impulsive integrodifferential systems in Hilbert spaces. The results are obtained by using the Nussbaum fixed-point theorem. Finally, two examples are presented to illustrate the utility of the proposed result.
Linear and Nonlinear Time-Frequency Analysis for Parameter Estimation of Resident Space Objects
2017-02-22
AFRL-AFOSR-UK-TR-2017-0023 Linear and Nonlinear Time-Frequency Analysis for Parameter Estimation of Resident Space Objects Marco Martorella... UNIVERSITY DI PISA, DEPARTMENT DI INGEGNERIA Final Report 02/22/2017 DISTRIBUTION A: Distribution approved for public release. AF Office Of Scientific Research...Nonlinear Time-Frequency Analysis for Parameter Estimation of Resident Space Objects 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-14-1-0183 5c. PROGRAM
Jeribi, Aref
2015-01-01
Uncover the Useful Interactions of Fixed Point Theory with Topological StructuresNonlinear Functional Analysis in Banach Spaces and Banach Algebras: Fixed Point Theory under Weak Topology for Nonlinear Operators and Block Operator Matrices with Applications is the first book to tackle the topological fixed point theory for block operator matrices with nonlinear entries in Banach spaces and Banach algebras. The book provides researchers and graduate students with a unified survey of the fundamental principles of fixed point theory in Banach spaces and algebras. The authors present several exten
Schrittwieser, R. W.; Ionita, C.; Teodorescu-Soare, C. T.; Vasilovici, O.; Gurlui, S.; Irimiciuc, S. A.; Dimitriu, D. G.
2017-04-01
Optical emission spectroscopy and Langmuir probes were used to diagnose complex space-charge structures that appear inside and around a spherical grid with orifice applying a negative voltage below a critical value to it. Measurements (through the orifice) delivered the axial profiles of plasma potential, electron temperature and density, and of the densities of excited atoms and ions. Thereby the formation of a double layer was found in the region near the orifice with a potential drop close to the ionisation potential of the applied gas, confirming the presence of a fireball in that region (also evidenced by visual observation), i.e. of a quasi-spherical bright plasma region consisting of a positive core (an ion-rich plasma) confined by a double layer. Spectral investigations confirmed the presence of high ion density inside the spherical grid (due to the hollow cathode effect), while outside the grid a transition region with a strong rate of ionisation and excitation processes appears. Information on the nonlinear dynamics of this space-charge structure was obtained from the analysis of the oscillations of the discharge current, as well as of the floating potential inside and outside the spherical grid. Dedicated to Hans Pécseli at the occasion of his 70th birthday, an extraordinary plasma physicist and a wonderful, noble and warm-hearted friend for more than 40 years.
Conserved charges in timelike Warped-AdS$_3$ spaces
Donnay, L; Giribet, G; Goya, A; Lavia, E
2015-01-01
We consider the timelike version of Warped Anti-de Sitter space (WAdS), which corresponds to the three-dimensional section of the G\\"{o}del solution of four-dimensional cosmological Einstein equations. This geometry presents closed timelike curves (CTCs), which are inherited from its four-dimensional embedding. In three dimensions, this type of solutions can be supported without matter provided the graviton acquires mass. Here, among the different ways to consistenly give mass to the graviton in three dimensions, we consider the parity-even model known as New Massive Gravity (NMG). In the bulk of timelike WAdS$_{3}$ space, we introduce defects that, from the three-dimensional point of view, represent spinning massive particle-like objects. For this type of sources, we investigate the definition of quasi-local gravitational energy as seen from infinity, far beyond the region where the CTCs appear. We also consider the covariant formalism applied to NMG to compute the mass and the angular momentum of spinning p...
Higher-spin fields and charges in the periodic spinor space
Goncharov, Y O
2016-01-01
The $sp(2M)$ invariant unfolded system is considered in the periodic twistor-like spinor space. Complete set of non-trivial charges corresponding to the global symmetry compatible with the periodicity conditions is constructed. Residual infinite-dimensional symmetry is realized in terms of the star-product algebra. It is shown that charges associated with integrations over different cycles are related by particular higher-spin symmetry transformations.
Gravitational collapse in higher-dimensional charged-Vaidya space-time
Indian Academy of Sciences (India)
Kishor D Patil
2003-03-01
We analyze here the gravitational collapse of higher-dimensional charged-Vaidya space-time. We show that singularities arising in a charged null ﬂuid in higher dimension are always naked violating at least strong cosmic censorship hypothesis (CCH), though not necessarily weak CCH. We show that earlier conclusions on the occurrence of naked singularities in four-dimensional case can be extended essentially in the same manner in 5D case also.
The nonlinear evolution of de Sitter space instabilities
Niemeyer, J C; Niemeyer, Jens C.; Bousso, Raphael
2000-01-01
We investigate the quantum evolution of large black holes that nucleate spontaneously in de Sitter space. By numerical computation in the s-wave and one-loop approximations, we verify claims that such black holes can initially "anti-evaporate" instead of shrink. We show, however, that this is a transitory effect. It is followed by an evaporating phase, which we are able to trace until the black holes are small enough to be treated as Schwarzschild. Under generic perturbations, the nucleated geometry is shown to decay into a ring of de Sitter regions connected by evaporating black holes. This confirms that de Sitter space is globally unstable and fragments into disconnected daughter universes.
Finite element method for nonlinear Riesz space fractional diffusion equations on irregular domains
Yang, Z.; Yuan, Z.; Nie, Y.; Wang, J.; Zhu, X.; Liu, F.
2017-02-01
In this paper, we consider two-dimensional Riesz space fractional diffusion equations with nonlinear source term on convex domains. Applying Galerkin finite element method in space and backward difference method in time, we present a fully discrete scheme to solve Riesz space fractional diffusion equations. Our breakthrough is developing an algorithm to form stiffness matrix on unstructured triangular meshes, which can help us to deal with space fractional terms on any convex domain. The stability and convergence of the scheme are also discussed. Numerical examples are given to verify accuracy and stability of our scheme.
General formula to deduce the space charge tune spread from a quadrupolar pick-up measurement
Metral, Elias
2016-01-01
In 1966, W. Hardt derived the oscillation frequencies obtained in the presence of space charge forces and gradients errors for elliptical beams. Since then, a simple formula is usually used to relate the shift of the quadrupolar mode (obtained from the quadrupolar pick-up) and the space charge tune spread, depending only on the ratio between the two transverse equilibrium beam sizes. However, this formula is not always valid, in particular for machines running close to the coupling resonance Qx = Qy with almost round beams. A new general formula is presented, giving the space charge tune spread as a function of i) the measured shift of the quadrupolar mode, ii) the ratio between the two transverse equilibrium beam sizes and iii) the distance between the two transverse tunes.
Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions
Energy Technology Data Exchange (ETDEWEB)
Valerio-Lizarraga, Cristhian A., E-mail: cristhian.alfonso.valerio.lizarraga@cern.ch [CERN, Geneva (Switzerland); Departamento de Investigación en Física, Universidad de Sonora, Hermosillo (Mexico); Lallement, Jean-Baptiste; Lettry, Jacques; Scrivens, Richard [CERN, Geneva (Switzerland); Leon-Monzon, Ildefonso [Facultad de Ciencias Fisico-Matematicas, Universidad Autónoma de Sinaloa, Culiacan (Mexico); Midttun, Øystein [CERN, Geneva (Switzerland); University of Oslo, Oslo (Norway)
2014-02-15
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H{sup −} beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
Space charge in drift chambers operated with the Xe, CO$_{2}$(15\\%) mixture
Andronic, A; Blume, C; Braun-Munzinger, P; Bucher, D; Busch, O; Catanescu, V; Ciobanu, M; Daues, H W; Emschermann, D; Fateev, O V; Foka, Y; Garabatos, C; Gunji, T; Herrmann, N; Inuzuka, M; Kislov, E; Lindenstruth, V; Ludolphs, W; Mahmoud, T; Petracek, V; Petrovici, M; Rusanov, I R; Sandoval, A; Santo, R; Schicker, R; Simon, R S; Smykov, L P; Soltveit, H K; Stachel, J; Stelzer, H; Tsiledakis, G; Vulpescu, B; Wessels, J P; Windelband, B; Xu, C; Zaudtke, O; Zanevsky, Yu; Yurevich, V
2004-01-01
Using prototype modules of the ALICE Transition Radiation Detector (TRD) we investigate space-charge effects and the dependence of the pion rejection performance on the incident angle of the ionizing particle. The average pulse height distributions in the drift chambers operated with the Xe, CO //2(15%) mixture provide quantitative information on the gas gain reduction due to space charge accumulating during the drift of the primary ionization. Our results demonstrate that the pion rejection performance of a TRD is better for tracks which are not at normal incidence to the anode wires. We present detailed simulations of detector signals, which reproduce the measurements and lend strong support to our interpretation of the measurements in terms of space-charge effects.
Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions.
Valerio-Lizarraga, Cristhian A; Lallement, Jean-Baptiste; Leon-Monzon, Ildefonso; Lettry, Jacques; Midttun, Øystein; Scrivens, Richard
2014-02-01
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H(-) beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions
Valerio-Lizarraga, Cristhian A.; Lallement, Jean-Baptiste; Leon-Monzon, Ildefonso; Lettry, Jacques; Midttun, Øystein; Scrivens, Richard
2014-02-01
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H- beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
Multi-turn injection into a heavy-ion synchrotron in the presence of space charge
Appel, Sabrina
2014-01-01
For heavy-ion synchrotrons an efficient Multi-Turn Injection (MTI) from the injector linac is crucial in order to reach the specified currents using the available machine acceptance. The beam loss during the MTI must not exceed the limits determined by machine protection and by the vacuum requirements. Especially for low energy and intermediate charge state ions, the beam loss at the injection septum can cause a degradation of the vacuum and a corresponding reduction of the beam lifetime. In order to optimize the injection of intense beams a very detailed simulation model was developed. Besides the closed orbit bump, lattice errors, the position of the septum and other aperture limiting components the transverse space charge force is included self-consistently. The space charge force causes a characteristic shift of the optimum tunes and a smoothing of the phase space density.
Forte, V.; Benedetto, E.; McAteer, M.
2016-12-01
The CERN Proton Synchrotron booster (PSB) is one of the machines of the LHC injector chain which will be upgraded within the LHC Injectors Upgrade (LIU) project. The injection energy of the PSB will be increased to 160 MeV in order to mitigate direct space charge effects, considered to be the main performance limitation, aiming to double the brightness for the LHC beams. In order to better predict the gain to be expected, space charge simulations are being carried out. As a first step, benchmarking between simulations and measurements is needed. Efforts to establish a realistic modeling of field and alignment errors aim at extending the basic model of the machine toward a more realistic one. Simulations of beam dynamics with strong space charge and realistic errors are presented and analyzed in this paper.
On Compensating Tune Spread Induced by Space Charge in Bunched Beams
Litvinenko, Vladimir N
2014-01-01
Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator - or - in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.
Adaptive matching of the iota ring linear optics for space charge compensation
Energy Technology Data Exchange (ETDEWEB)
Romanov, A. [Fermilab; Bruhwiler, D. L. [RadiaSoft, Boulder; Cook, N. [RadiaSoft, Boulder; Hall, C. [RadiaSoft, Boulder
2016-10-09
Many present and future accelerators must operate with high intensity beams when distortions induced by space charge forces are among major limiting factors. Betatron tune depression of above approximately 0.1 per cell leads to significant distortions of linear optics. Many aspects of machine operation depend on proper relations between lattice functions and phase advances, and can be i proved with proper treatment of space charge effects. We implement an adaptive algorithm for linear lattice re matching with full account of space charge in the linear approximation for the case of Fermilab’s IOTA ring. The method is based on a search for initial second moments that give closed solution and, at the same predefined set of goals for emittances, beta functions, dispersions and phase advances at and between points of interest. Iterative singular value decomposition based technique is used to search for optimum by varying wide array of model parameters
Space Charge Effects and Advanced Modelling for CERN Low Energy Machines
AUTHOR|(CDS)2088716; Rumolo, Giovanni
The strong space charge regime of future operation of CERN’s circular particle accelerators is investigated and mitigation strategies are developed in the framework of the present thesis. The intensity upgrade of the injector chain of Large Hadron Collider (LHC) prepares the particle accelerators to meet the requirements of the High-Luminosity LHC project. Producing the specified characteristics of the future LHC beams imperatively relies on injecting brighter bunches into the Proton Synchrotron Booster (PSB), the downstream Proton Synchrotron (PS) and eventually the Super Proton Synchrotron (SPS). The increased brightness, i.e. bunch intensity per transverse emittance, entails stronger beam self-fields which can lead to harmful interaction with betatron resonances. Possible beam emittance growth and losses as a consequence thereof threaten to degrade the beam brightness. These space charge effects are partly mitigated by the upgrade of the PSB and PS injection energies. Nevertheless, the space charge tune ...
The magnetized dusty plasma discharge negative and positive space charge modes
Cramer, N F; Cramer, Neil F.; Vladimirov, Sergey
2004-01-01
The structure of a discharge across a magnetic field in a dusty plasma is analysed. The dust macroparticles are negatively charged, but are unmagnetized because of their high mass. The electrons are highly magnetized, and the ions have intermediate magnetization. This results in different transport rates of the different species across the magnetic field. Depending on the size of the magnetic field, and the relative charge on the different species, the dust grains can be the dominant current carrier. The space charge clouds near the electrodes will then be determined by the relative mobility of the different species. The discharge can operate in one of two modes, a positive space charge (PSC) mode, characterized by a strong cathode fall, and a negative space charge (NSC) mode, characterized by a broad anode fall. Features unique to the dust particles can also play a role in the structure of the discharge, such as the variable equilibrium charge on the grains, dependent on the local potential and species tempe...
Space Charge Correction on Emittance Measurement of Low Energy Electron Beams
Energy Technology Data Exchange (ETDEWEB)
Treado, Colleen J.; /Massachusetts U., Amherst
2012-09-07
The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.
Harada, Hiroshi; Hayashi, Nobuya; Tanaka, Yasuhiro; Maeno, Takashi; Mizuno, Takehiko; Takahashi, Tohru
We have observed space charge profiles in cross-linked polyethylene (XLPE) under dc high electric field using the PEA (pulsed electro-acoustic) system to study the relationship between space charge behavior and dielectric breakdown. In our previous research work, we have found that a large amount of, so called, packet-like charge generates in low density polyethylene (LDPE) under high dc electric field of more than 100 kV/mm. The packet-like charge enhances the electric field locally in bulk of the sample, and then finally it leads a breakdown. On the other hand, a new type of XLPE which was made through adding conductive inorganic fillers, shows a good dc dielectric breakdown characteristic and high volume resistivity under dc stress. In this report, we tried to observe the space charge behavior under high dc electric field in this material. From the results, it is found that the charge injection is effectively suppressed by adding only a small amount of conductive inorganic fillers to XLPE.
Nonlinear dynamics of phase space zonal structures and energetic particle physics in fusion plasmas
Zonca, Fulvio; Briguglio, Sergio; Fogaccia, Giuliana; Vlad, Gregorio; Wang, Xin
2014-01-01
A general theoretical framework for investigating nonlinear dynamics of phase space zonal structures is presented in this work. It is then, more specifically, applied to the limit where the nonlinear evolution time scale is smaller or comparable to the wave-particle trapping period. In this limit, both theoretical and numerical simulation studies show that non-adiabatic frequency chirping and phase locking could lead to secular resonant particle transport on meso- or macro-scales. The interplay between mode structures and resonant particles then provides the crucial ingredient to properly understand and analyze the nonlinear dynamics of Alfv\\'en wave instabilities excited by non-perturbative energetic particles in burning fusion plasmas. Analogies with autoresonance in nonlinear dynamics and with superradiance in free electron lasers are also briefly discussed.
Hawking radiation of charged Dirac particles in Vaidya-Bonner space-time
Institute of Scientific and Technical Information of China (English)
朱建阳; 张建华; 赵峥
1995-01-01
The dynamical properties of charged Dirac spinor particles in the Vaidya-Bonner space-time are investigated. The asymptotic solution to the radial part of the charged Dirac equation near the event horizon of the black hole is obtained. The Hawking temperature and the event horizon of the charged evaporating black hole, as well as the spectrum of the Hawking radiation of the Dirac particles, are exactly shown. Thereby, a new approach to the back-reaction of radiation from the non-stationary black holes is established.
Condition for production of circulating proton beam with intensity greater than space charge limit.
Energy Technology Data Exchange (ETDEWEB)
Vadim Dudnikov
2002-11-19
Transverse e-p instability in proton rings could be damped by increasing the beam density and the rate of secondary particles production above the threshold level, with the corresponding decrease of unstable wavelength {lambda} below the transverse beam size h (increase of beam density n{sub b} and ion density n{sub i} above the threshold level: n{sub b} + n{sub i} > {beta}{sup 2}/(r{sub e} h{sup 2}), where r{sub e} = e{sup 2}/mc{sup 2}). Such island of stability can be reached by a fast charge-exchange injection without painting and enhanced generation of secondary plasma, which was demonstrated in a small scale Proton Storage Ring (PSR) at the Institute of Nuclear Physics, Novosibirsk, Russia. With successful damping of e-p instability, the intensity of circulating proton beam, with a space charge neutralization was increased up to 6 times above a space charge limit. Corresponding tune shift without space charge neutralization should be up to {Delta}v=0.85 x 6 (in the ring with v = 0.85). In this paper, they review experimental observations of transverse instability of proton beams in various rings. they also discuss methods which can be used to damp the instability. Such experimental data could be useful for verification of computer simulation tools developed for the studies of the space charge and instabilities in realistic conditions.
Existence and Boundedness of Solutions for Nonlinear Volterra Difference Equations in Banach Spaces
Directory of Open Access Journals (Sweden)
Rigoberto Medina
2016-01-01
Full Text Available We consider a class of nonlinear discrete-time Volterra equations in Banach spaces. Estimates for the norm of operator-valued functions and the resolvents of quasi-nilpotent operators are used to find sufficient conditions that all solutions of such equations are elements of an appropriate Banach space. These estimates give us explicit boundedness conditions. The boundedness of solutions to Volterra equations with infinite delay is also investigated.
Olson, Benjamin Varberg
All-optical time-resolved measurement techniques provide a powerful tool for investigating critical parameters that determine the performance of infrared photodetector and emitter semiconductor materials. Narrow-bandgap InAs/GaSb type-II superlattices (T2SLs) have shown great promise as a next generation source of these materials, due to superior intrinsic properties and versatility. Unfortunately, InAs/GaSb T2SLs are plagued by parasitic Shockley-Read-Hall recombination centers that shorten the carrier lifetime and limit device performance. Ultrafast pump-probe techniques and time-resolved differential transmission measurements are used here to demonstrate that Ga-free InAs/InAsSb T2SLs and InAsSb alloys do not have this same limitation and thus have significantly longer carrier lifetimes. Measurements at 77 K provided minority carrier lifetimes of 9 mus and 3 mus for an unintentionally doped mid-wave infrared (MWIR) InAs/InAsSb T2SL and InAsSb alloy, respectively; a two order of magnitude increase compared to the 90 ns minority carrier lifetime measured in a comparable MWIR InAs/GaSb T2SL. Through temperature-dependent lifetime measurements, the various carrier recombination processes are differentiated and the dominant mechanisms identified for each material. These results demonstrate that these Ga-free materials are viable options over InAs/GaSb T2SLs for potentially improved infrared photodetectors. In addition to carrier lifetimes, the drift and diffusion of excited charge carriers through the superlattice growth layers (i.e. vertical transport) directly affects the performance of photodetectors and emitters. Unfortunately, there is a lack of information pertaining to vertical transport, primarily due to difficulties in making measurements on thin growth layers and the need for non-standard measurement techniques. However, all-optical ultrafast techniques are successfully used here to directly measure vertical diffusion in MWIR InAs/GaSb T2SLs. By optically
Nonlinear state space model identification of synchronous generators
Energy Technology Data Exchange (ETDEWEB)
Dehghani, M.; Nikravesh, S.K.Y. [Electrical Engineering Department, Amirkabir University of Technology, Tehran (Iran)
2008-05-15
A method for identification of a synchronous generator is suggested in this paper. The method uses the theoretical relations of machine parameters and the Prony method to find the state space model of the system. Such models are useful for controller design and stability tests. The proposed identification method is applied to a third order model of a synchronous generator. In this study, the field voltage is considered as the input and the active output power and the rotor angle are considered as the outputs of the synchronous generator. Simulation results show good accuracy of the identified model. (author)
DEFF Research Database (Denmark)
Bambery, K.R.; Fleming, R.J.; Holbøll, Joachim
2001-01-01
Laser induced pressure pulse space charge measurements were made on 1.5 mm thick plaques of high purity low density polyethylene equipped with vacuum-evaporated aluminium electrodes. Temperature differences up to 20 °C were maintained across the samples, which were subjected to dc fields up to 1.......5×107 V m-1. Current density was also measured as a function of temperature and field. Space charge due exclusively to the temperature gradient was detected, with density of order 0.01 C m-3. The activation energy associated with the transport of electrons through the bulk was calculated as 0.09 e...
Energy Technology Data Exchange (ETDEWEB)
Halavanau, A. [Northern Illinois U.; Piot, P. [Northern Illinois U.
2015-12-01
Cascaded Longitudinal Space Charge Amplifiers (LSCA) have been proposed as a mechanism to generate density modulation over a board spectral range. The scheme has been recently demonstrated in the optical regime and has confirmed the production of broadband optical radiation. In this paper we investigate, via numerical simulations, the performance of a cascaded LSCA beamline at the Fermilab Accelerator Science & Technology (FAST) facility to produce broadband ultraviolet radiation. Our studies are carried out using elegant with included tree-based grid-less space charge algorithm.
CIRCULAR CRACK IN A TRANSVERSELY ISOTROPIC PIEZOELECTRIC SPACE UNDER POINT FORCES AND POINT CHARGES
Institute of Scientific and Technical Information of China (English)
侯鹏飞; 丁皓江; 关富玲
2002-01-01
In this paper, two kinds of circular crack including external circular crack and penny-shaped crack in a transversely isotropic piezoelectric space are considered. Firstly, we obtain the solution to the problem of an external circular crack in a transversely isotropic piezoelectric space subjected to antisymmetric normal point forces and point charges. Based on this, the solution of one-sided loading of an external circular crack is constructed. Secondly, the real shape of an external circular crack and the opening displacement of a penny-shaped crack under an arbitrary point force and point charge are further obtained. At last, the results are presented in a graphical form.
CrossRef Space-charge effects in Penning ion traps
Porobić, T; Breitenfeldt, M; Couratin, C; Finlay, P; Knecht, A; Fabian, X; Friedag, P; Fléchard, X; Liénard, E; Ban, G; Zákoucký, D; Soti, G; Van Gorp, S; Weinheimer, Ch; Wursten, E; Severijns, N
2015-01-01
The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with View the MathML source using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.
The Effect of the Semiconductive Screen on Space Charge Suppression in Cross-Linked Polyethylene
Li, Lin; Han, Bai; Song, Wei; Wang, Xuan; Lei, Qing-Quan
2014-10-01
The space charge distributions of cross-linked polyethylene (XLPE) with Borouge's Borlink™ semiconductive screen type LE0550 and LE0595 from a pulsed electro-acoustic method are obtained. The contact interface morphology at the semiconductive screen and the structure of XLPE near the interface are characterized. The dielectric spectrum and the conductivity current of XLPE with the different semiconductive electrodes are compared. The semiconductive screen changes the structure and the dielectric characteristic of XLPE near the contact interface, which may be the main reason for space charge suppression in XLPE with Borouge's type LE0550 semiconductive screen.
Spins and charges in Grassmann space and Kähler spinors in space of differential forms
Borstnik, Norma Mankoc; Borstnik, Norma Mankoc; Nielsen, Holger Bech
1999-01-01
One of us got spins and charges of not only scalars and vectors but also of spinors out of fields, which are antisymmetric tensor fields. Kahler got spins of spinors out of differential forms, which again are antisymmetric tensor fields. Using our simple Grassmann formulation of spins and charges of either spinors or vectors and comparing it to the Dirac-Kahler formulation of spinors, we generalize the Dirac-Kahler approach to vector internal degrees of freedom and to charges of either spinors or vectors and tenzors and point out how at all spinors can appear in both approaches.
On the correct formulation of a nonlinear differential equations in Banach space
Directory of Open Access Journals (Sweden)
Mahmoud M. El-Borai
2001-01-01
Full Text Available We study, the existence and uniqueness of the initial value problems in a Banach space E for the abstract nonlinear differential equation (dn−1/dtn−1(du/dt+Au=B(tu+f(t,W(t, and consider the correct solution of this problem. We also give an application of the theory of partial differential equations.
Institute of Scientific and Technical Information of China (English)
Tetsuya Ishiwata; Masayoshi Tsutsumi
2000-01-01
Semidiscretization in space of nonlinear degenerate parabolic equations of nondivergent form is presented, under zero Dirichlet boundary condition. It is shown that semidiscrete solutions blow up in finite time. In particular, the asymptotic behavior of blowing-up solutions, is discussed precisely.
Variational space-time (dis)continuous Galerkin method for nonlinear free surface waves
Gagarina, E.; Vegt, van der J.J.W.; Ambati, V.R.; Bokhove, O.
2013-01-01
A new variational finite element method is developed for nonlinear free surface gravity water waves. This method also handles waves generated by a wave maker. Its formulation stems from Miles' variational principle for water waves together with a space-time finite element discretization that is cont
Integrability of Nonlinear Equations of Motion on Two-Dimensional World Sheet Space-Time
Institute of Scientific and Technical Information of China (English)
YAN Jun
2005-01-01
The integrability character of nonlinear equations of motion of two-dimensional gravity with dynamical torsion and bosonic string coupling is studied in this paper. The space-like and time-like first integrals of equations of motion are also found.
Pandey, Ravindra; Ghosh, Sampa; Mukhopadhyay, S; Ramasesha, S; Das, Puspendu K
2011-01-28
We report large quadratic nonlinearity in a series of 1:1 molecular complexes between methyl substituted benzene donors and quinone acceptors in solution. The first hyperpolarizability, β(HRS), which is very small for the individual components, becomes large by intermolecular charge transfer (CT) interaction between the donor and the acceptor in the complex. In addition, we have investigated the geometry of these CT complexes in solution using polarization resolved hyper-Rayleigh scattering (HRS). Using linearly (electric field vector along X direction) and circularly polarized incident light, respectively, we have measured two macroscopic depolarization ratios D=I(2ω,X,X)/I(2ω,Z,X) and D(')=I(2ω,X,C)/I(2ω,Z,C) in the laboratory fixed XYZ frame by detecting the second harmonic scattered light in a polarization resolved fashion. The experimentally obtained first hyperpolarizability, β(HRS), and the value of macroscopic depolarization ratios, D and D('), are then matched with the theoretically deduced values from single and double configuration interaction calculations performed using the Zerner's intermediate neglect of differential overlap self-consistent reaction field technique. In solution, since several geometries are possible, we have carried out calculations by rotating the acceptor moiety around three different axes keeping the donor molecule fixed at an optimized geometry. These rotations give us the theoretical β(HRS), D and D(') values as a function of the geometry of the complex. The calculated β(HRS), D, and D(') values that closely match with the experimental values, give the dominant equilibrium geometry in solution. All the CT complexes between methyl benzenes and chloranil or 1,2-dichloro-4,5-dicyano-p-benzoquinone investigated here are found to have a slipped parallel stacking of the donors and the acceptors. Furthermore, the geometries are staggered and in some pairs, a twist angle as high as 30° is observed. Thus, we have demonstrated in
Effect of ion compensation of the beam space charge on gyrotron operation
Energy Technology Data Exchange (ETDEWEB)
Fokin, A. P.; Glyavin, M. Yu. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Nusinovich, G. S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)
2015-04-15
In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.
Nonlinear scale space with spatially varying stopping time.
Gilboa, Guy
2008-12-01
A general scale space algorithm is presented for denoising signals and images with spatially varying dominant scales. The process is formulated as a partial differential equation with spatially varying time. The proposed adaptivity is semi-local and is in conjunction with the classical gradient-based diffusion coefficient, designed to preserve edges. The new algorithm aims at maximizing a local SNR measure of the denoised image. It is based on a generalization of a global stopping time criterion presented recently by the author and colleagues. Most notably, the method works well also for partially textured images and outperforms any selection of a global stopping time. Given an estimate of the noise variance, the procedure is automatic and can be applied well to most natural images.
Free-Space Nonlinear Beam Combining Towards Filamentation
Rostami, Shermineh; Kepler, Daniel; Baudelet, Matthieu; Litchinitser, Natalia M; Richardson, Martin
2016-01-01
Multi-filamentation opens new degrees of freedom for manipulating electromagnetic waves in air. However, without control, multiple filament interactions, including attraction, repulsion or fusion often result in formation of complex disordered filament distributions. Moreover, high power beams conventionally used in multi-filament formation experiments often cause significant surface damage. The growing number of applications for laser filaments requires fine control of their formation and propagation. We demonstrate, experimentally and theoretically, that the attraction and fusion of ultrashort beams with initial powers below the critical value enable the eventual formation of a filament downstream. Filament formation is delayed to a predetermined distance in space, avoiding optical damage to external beam optics while still enabling robust filaments with controllable properties as if formed from a single high power beam. This paradigm introduces new opportunities for filament engineering eliminating the nee...
Balthazor, R. L.; McHarg, M. G.; Wilson, G.
2016-12-01
The Integrated Miniaturized Electrostatic Analyzer (IMESA) is a space weather sensor developed by the United States Air Force Academy and integrated and flown by the DoD's Space Test Program. IMESA records plasma spectrograms from which can be derived plasma density, temperature, and spacecraft frame charging. Results from IMESA currently orbiting on STPSat-3 are presented, showing frame charging effects dependent on a complex function of the number of solar panel cell strings switched in, solar panel current, and plasma density. IMESA will fly on four more satellites launching in the next two calendar years, enabling an undergraduate DoD space weather constellation in Low Earth Orbit that has the ability to significantly improve space weather forecasting capabilities using assimilative forecast models.
Liu, Peipei; Sohn, Hoon; Park, Byeongjin
2015-06-01
Damage often causes a structural system to exhibit severe nonlinear behaviors, and the resulting nonlinear features are often much more sensitive to the damage than their linear counterparts. This study develops a laser nonlinear wave modulation spectroscopy (LNWMS) so that certain types of damage can be detected without any sensor placement. The proposed LNWMS utilizes a pulse laser to generate ultrasonic waves and a laser vibrometer for ultrasonic measurement. Under the broadband excitation of the pulse laser, a nonlinear source generates modulations at various frequency values due to interactions among various input frequency components. State space attractors are reconstructed from the ultrasonic responses measured by LNWMS, and a damage feature called Bhattacharyya distance (BD) is computed from the state space attractors to quantify the degree of damage-induced nonlinearity. By computing the BD values over the entire target surface using laser scanning, damage can be localized and visualized without relying on the baseline data obtained from the pristine condition of a target structure. The proposed technique has been successfully used for visualizing fatigue crack in an aluminum plate and delamination and debonding in a glass fiber reinforced polymer wind turbine blade.
Numerical Study on the Charge Transport in a Space between Concentric Circular Cylinders
Directory of Open Access Journals (Sweden)
Y. K. Suh
2014-01-01
Full Text Available Electrification is one of the key factors to be considered in the design of power transformers utilizing dielectric liquid as a coolant. Compared with enormous quantity of experimental and analytical studies on electrification, numerical simulations are very few. This paper describes essential elements of numerical solution methods for the charge transport equations in a space between concentric cylinders. It is found that maintaining the conservation property of the convective terms in the governing equations is of the uttermost importance for numerical accuracy, in particular at low reaction rates. Parametric study on the charge transport on the axial plane of the annular space with a predetermined velocity shows that when the convection effect is weak the solutions tend to a one-dimensional nature, where diffusion is simply balanced by conduction. As the convection effect is increased the contours of charge distribution approach the fluid streamlines. Thus, when the conduction effect is weak, charge distribution tends to be uniform and the role of the convection effect becomes insignificant. At an increased conduction effect, on the other hand, the fluid motion transports the charge within the electric double layers toward the top and bottom boundaries leading to an increased amount of total charge in the domain.
Numerical study for production of space charge within the stratiform cloud
Indian Academy of Sciences (India)
A K Srivastava; S N Tripathi
2010-10-01
One dimensional numerical model has been developed to predict the production of space charge and variations in other electrical parameters within the low level stratiform type of cloud having very weak vertical motion.Non-linear coupled differential equations which govern ion concentrations,charged and neutral droplet concentrations and electric ﬁeld were used.Symmetry has been observed in all the electrical parameters within the cloud.The magnitude of average positive ion concentrations was observed to be high as compared to the negative ion concentrations,which is due to low scavenging rate of positive ions than the negative ions,highly attributed to their mobilities.The rate of scavenging of ions affects the concentration of charged droplets,which eventually inﬂuence the electric ﬁeld and thus the space charge density within the cloud.Maximum electric ﬁeld (max) was observed at middle of the cloud whereas minimum was observed at both the edges of the cloud.Minimum electric ﬁeld (min) was found to be equal and constant (∼27Vm−1)for any drop concentration.Net positive and negative space charges were observed at the top and bottom of the cloud,respectively.The simulated results show some discrepancies to the natural condition, which are due to simulations made under some basic assumptions and limitations and that will be incorporated in the future studies for natural cloud condition.
Chaotic behaviour of nonlinear coupled reaction–diffusion system in four-dimensional space
Indian Academy of Sciences (India)
Li Zhang; Shutang Liu; Chenglong Yu
2014-06-01
In recent years, nonlinear coupled reaction–diffusion (CRD) system has been widely investigated by coupled map lattice method. Previously, nonlinear behaviour was observed dynamically when one or two of the three variables in the discrete system change. In this paper, we consider the chaotic behaviour when three variables change, which is called as four-dimensional chaos. When two parameters in the discrete system are unknown, we first give the existing condition of the chaos in four-dimensional space by the generalized definitions of spatial periodic orbits and spatial chaos. In addition, the chaotic behaviour will vary with the parameters. Then we propose a generalized Lyapunov exponent in four-dimensional space to characterize the different effects of parameters on the chaotic behaviour, which has not been studied in detail. In order to verify the chaotic behaviour of the system and the different effects clearly, we simulate the dynamical behaviour in two- and three-dimensional spaces.
Existence Results for Differential Inclusions with Nonlinear Growth Conditions in Banach Spaces
Directory of Open Access Journals (Sweden)
Messaoud Bounkhel
2013-01-01
Full Text Available In the Banach space setting, the existence of viable solutions for differential inclusions with nonlinear growth; that is, ẋ(t∈F(t,x(t a.e. on I, x(t∈S, ∀t∈I, x(0=x0∈S, (*, where S is a closed subset in a Banach space , I=[0,T], (T>0, F:I×S→, is an upper semicontinuous set-valued mapping with convex values satisfying F(t,x⊂c(tx+xp, ∀(t,x∈I×S, where p∈ℝ, with p≠1, and c∈C([0,T],ℝ+. The existence of solutions for nonconvex sweeping processes with perturbations with nonlinear growth is also proved in separable Hilbert spaces.
DEFF Research Database (Denmark)
Holbøll, Joachim; Bambery, K. R.; Fleming, R. J.
2000-01-01
Electromagnetic theory predicts that a dielectric sample in which a steady DC current of density ε is flowing, and in which the ratio of permittivity ε to conductivity σ varies with position, will acquire a space charge density j·grad(ε/σ). A simple and convenient way to generate an ε/σ gradient...... in a homogeneous sample is to establish a temperature gradient across it. The resulting spatial variation in ε is usually small in polymeric insulators, but the variation in σ can be appreciable. Laser induced pressure pulse (LIPP) measurements were made on 1.5 mm thick plaques of ultra pure LDPE equipped...... with vacuum-evaporated aluminium electrodes. Temperature differences up to 27°C were maintained across the samples, which were subjected to DC fields up to 20 kV/mm. Current density was measured as a function of temperature and field. Negligible thermally generated space charge was observed. The charge...
Sun, Xiaodian; Jin, Li; Xiong, Momiao
2008-01-01
It is system dynamics that determines the function of cells, tissues and organisms. To develop mathematical models and estimate their parameters are an essential issue for studying dynamic behaviors of biological systems which include metabolic networks, genetic regulatory networks and signal transduction pathways, under perturbation of external stimuli. In general, biological dynamic systems are partially observed. Therefore, a natural way to model dynamic biological systems is to employ nonlinear state-space equations. Although statistical methods for parameter estimation of linear models in biological dynamic systems have been developed intensively in the recent years, the estimation of both states and parameters of nonlinear dynamic systems remains a challenging task. In this report, we apply extended Kalman Filter (EKF) to the estimation of both states and parameters of nonlinear state-space models. To evaluate the performance of the EKF for parameter estimation, we apply the EKF to a simulation dataset and two real datasets: JAK-STAT signal transduction pathway and Ras/Raf/MEK/ERK signaling transduction pathways datasets. The preliminary results show that EKF can accurately estimate the parameters and predict states in nonlinear state-space equations for modeling dynamic biochemical networks.
Gain Scheduling Control of Nonlinear Systems Based on Neural State Space Models
DEFF Research Database (Denmark)
Bendtsen, Jan Dimon; Stoustrup, Jakob
2003-01-01
This paper presents a novel method for gain scheduling control of nonlinear systems based on extraction of local linear state space models from neural networks with direct application to robust control. A neural state space model of the system is first trained based on in- and output training...... samples from the system, after which linearized state space models are extracted from the neural network in a number of operating points according to a simple and computationally cheap scheme. Robust observer-based controllers can then be designed in each of these operating points,and gain scheduling...
Theory of space-charge polarization for determining ionic constants of electrolytic solutions.
Sawada, Atsushi
2007-06-14
A theoretical expression of the complex dielectric constant attributed to space-charge polarization has been derived under an electric field calculated using Poisson's equation considering the effects of bound charges on ions. The frequency dependence of the complex dielectric constant of chlorobenzene solutions doped with tetrabutylammonium tetraphenylborate (TBATPB) has been analyzed using the theoretical expression, and the impact of the bound charges on the complex dielectric constant has been clarified quantitatively in comparison with a theory that does not consider the effect of the bound charges. The Stokes radius of TBA+(=TPB-) determined by the present theory shows a good agreement with that determined by conductometry in the past; hence, the present theory should be applicable to the direct determination of the mobility of ion species in an electrolytic solution without the need to measure ionic limiting equivalent conductance and transport number.
Near-wall conductivity effect under a space-charge-saturated sheath in the Hall thruster
Institute of Scientific and Technical Information of China (English)
Zhang Feng-Kui; Ding Yong-Jie; Qing Shao-Wei; Wu Xian-De
2011-01-01
In this paper,we adopt the modified Morozov secondary electron emission model to investigate the influence of the characteristic of a space-charge-saturated sheath near the insulated wall of the Hall thruster on the near-wall conductivity,by the method of two-dimensional (2D) particle simulation (2D+3V).The results show that due to the sharp increase of collision frequency between the electrons and the wall under the space-charge-saturated sheath,the near-wall transport current under this sheath is remarkably higher than that under a classical sheath,and equals the near-wall transport current under a spatially oscillating sheath in order of magnitude.However,the transport currents under a space-charge-saturated sheath and a spatially oscillating sheath are different in mechanism,causing different current density distributions under the above two sheaths,and a great influence of channel width on the near-wall transport current under a space-charge-saturated sheath.
An efficient method for the analysis of the space-charge region of diffused junctions
Eltoukhy, A. A.; Roulston, D. J.
1982-08-01
An efficient numerical method is presented which gives the solution for electrostatic potential, carrier density and space charge density distribution of an asymetrical junction. This method is based on the numerical solution of Poisson's equation assuming a zero-current approximation. A comparison between the present method and two different methods is made.
Space Charge Formation in XLPE - the Influence of Electrodes and Pre-conditioning
DEFF Research Database (Denmark)
Holbøll, Joachim T.; Henriksen, Mogens; Fleming, R.J.
1999-01-01
The composition of the inner and outer “semicon” shields in modern ac cables, and the temperature/pressure conditions under which the various manufacturing procedures are carried out, would be expected to influence space charge accumulation under dc stress significantly. However, few systematic i...... as vacuum-evaporated gold. The samples were also subjected to three different heating/pumping conditioning procedures....
Reducing Space Charge Effects in a Linear Ion Trap by Rhombic Ion Excitation and Ejection
Zhang, Xiaohua; Wang, Yuzhuo; Hu, Lili; Guo, Dan; Fang, Xiang; Zhou, Mingfei; Xu, Wei
2016-07-01
Space charge effects play important roles in ion trap operations, which typically limit the ion trapping capacity, dynamic range, mass accuracy, and resolving power of a quadrupole ion trap. In this study, a rhombic ion excitation and ejection method was proposed to minimize space charge effects in a linear ion trap. Instead of applying a single dipolar AC excitation signal, two dipolar AC excitation signals with the same frequency and amplitude but 90° phase difference were applied in the x- and y-directions of the linear ion trap, respectively. As a result, mass selective excited ions would circle around the ion cloud located at the center of the ion trap, rather than go through the ion cloud. In this work, excited ions were then axially ejected and detected, but this rhombic ion excitation method could also be applied to linear ion traps with ion radial ejection capabilities. Experiments show that space charge induced mass resolution degradation and mass shift could be alleviated with this method. For the experimental conditions in this work, space charge induced mass shift could be decreased by ~50%, and the mass resolving power could be improved by ~2 times at the same time.
Andritsch, T.M.
2010-01-01
Main goal of the research described in this PhD thesis was to determine the influences of filler size, material and distribution on the DC breakdown strength, permittivity and space charge behaviour of nanocomposites. This should lay the groundwork for tailored insulation materials for HVDC
Space Charge Distribution Measurement in Insulation Film with Thickness of Several Tens μm
Hamano, Akihiro; Tanaka, Yasuhiro; Maeno, Takashi
Since electronic equipment is required to be smaller and lighter, an insulating material for such equipment is consequently required to be thinner. However, under a certain DC voltage, the electric field in it becomes relatively higher according to the insulating material becomes thinner. Therefore, the insulating performance under high electric field must be important in such thin films. On the other hand, it is said that a space charge accumulation in them under DC high electric field is important because sometimes an electrical breakdown occurs in them due to an enhancement of electric field induced by the accumulated space charge. To investigate the characteristics of the space charge accumulation in them, PEA (Pulsed Electroacoustic) method is usually used. However, a spatial resolution of ordinary PEA system is not enough to observe the space charge distribution in thin films with thickness of several tens μm. Therefore, a new measurement system with high positional resolution is developed by making a thin piezo-electric film that is used as a sensor for PEA system. The obtained resolution of the developed system is 4 μm, and it is used for a typical measurement in LDPE film with thickness of 40 μm.
Andritsch, T.M.
2010-01-01
Main goal of the research described in this PhD thesis was to determine the influences of filler size, material and distribution on the DC breakdown strength, permittivity and space charge behaviour of nanocomposites. This should lay the groundwork for tailored insulation materials for HVDC applicat
DEFF Research Database (Denmark)
Bambery, K.R.; Fleming, R.J.; Holbøll, Joachim
2001-01-01
.5×107 V m-1. Current density was also measured as a function of temperature and field. Space charge due exclusively to the temperature gradient was detected, with density of order 0.01 C m-3. The activation energy associated with the transport of electrons through the bulk was calculated as 0.09 e...
Space Charge Compensation Using Electron Columns and Electron Lenses at IOTA
Energy Technology Data Exchange (ETDEWEB)
Park, Chong Shik [Fermilab; Shiltsev, Vladimir [Fermilab; Stancari, Giulio [Fermilab; Thangaraj, Jayakar Tobin [Fermilab; Milana, Diletta [Milan Polytechnic
2016-11-10
The ability to transport a high current proton beam in a ring is ultimately limited by space charge effects. Two novel ways to overcome this limit in a proton ring are by adding low energy, externally matched electron beams (electron lens, e-lens), and by taking advantage of residual gas ionization induced neutralization to create an electron column (e-column). Theory predicts that an appropriately confined electrons can completely compensate the space charge through neutralization, both transversely and longitudinally. In this report, we will discuss the current status of the Fermilab’s e-lens experiment for the space charge compensation. In addition, we will show how the IOTA e-column compensates space charge with theWARP simulations. The dynamics of proton beams inside of the e-column is understood by changing the magnetic field of a solenoid, the voltage on the electrodes, and the vacuum pressure, and by looking for electron accumulation, as well as by considering various beam dynamics in the IOTA ring.
Calculation and measurement of space charge in MV-size xxtruded cables systems under load conditions
Morshuis, P.H.F.; Bodega, R.; Fabiani, D.; Montanari, G.C.; Dissado, L.A; Smit, J.J.
2007-01-01
A load current in dc high voltage cables results in a temperature drop across the insulation and hence a radial distribution of the insulation conductivity is found. Direct consequence is an accumulation of space charge in the bulk of the nsulation, that may significantly affect its reliability. Thi
Space charge build-up in XLPE-cable with temperature gradient
DEFF Research Database (Denmark)
Holbøll, Joachim; Henriksen, Mogens; Hjerrild, Jesper
2000-01-01
Space charge build-up in standard XLPE insulated AC cables has been studied under varying temperature and field conditions. The cables were triple-extruded with the inner semicon on a solid aluminum conductor, 5.5mm XLPE-insulation and an outer semicon. The cables were stressed up to 15kV/mm DC...
The Influence of Pre-conditioning on the Space Charge Formation in LDPE and XLPE
DEFF Research Database (Denmark)
Henriksen, Mogens; Holbøll, Joachim T.; Fleming, R.J.
1996-01-01
Planar LDPE and XLPE samples were conditioned by holding in short circuit for 48 hrs. at 40oC under rotary pump pressure, and space charge accumulation in these samples under DC fields of 20 kV/mm was then compared with the corresponding accumulation in unconditioned samples.The test results were...
Recursive prediction error methods for online estimation in nonlinear state-space models
Directory of Open Access Journals (Sweden)
Dag Ljungquist
1994-04-01
Full Text Available Several recursive algorithms for online, combined state and parameter estimation in nonlinear state-space models are discussed in this paper. Well-known algorithms such as the extended Kalman filter and alternative formulations of the recursive prediction error method are included, as well as a new method based on a line-search strategy. A comparison of the algorithms illustrates that they are very similar although the differences can be important for the online tracking capabilities and robustness. Simulation experiments on a simple nonlinear process show that the performance under certain conditions can be improved by including a line-search strategy.
Modulation of waves due to charge-exchange collisions in magnetized partially ionized space plasma
Energy Technology Data Exchange (ETDEWEB)
Shaikh, Dastgeer, E-mail: dastgeer.shaikh@uah.ed [Department of Physics and Center for Space Plasma and Aeronomy Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Zank, G.P. [Department of Physics and Center for Space Plasma and Aeronomy Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)
2010-10-04
A nonlinear time dependent fluid simulation model is developed that describes the evolution of magnetohydrodynamic waves in the presence of collisional and charge exchange interactions of a partially ionized plasma. The partially ionized plasma consists of electrons, ions and a significant number of neutral atoms. In our model, the electrons and ions are described by a single fluid compressible magnetohydrodynamic (MHD) model and are coupled self-consistently to the neutral gas, described by the compressible hydrodynamic equations. Both the plasma and neutral fluids are treated with different energy equations that describe thermal energy exchange processes between them. Based on our self-consistent model, we find that propagating Alfvenic and fast/slow modes grow and damp alternately through a nonlinear modulation process. The modulation appears to be robust and survives strong damping by the neutral component.
Modulation of waves due to charge-exchange collisions in magnetized partially ionized space plasma
Shaikh, Dastgeer
2010-01-01
A nonlinear time dependent fluid simulation model is developed that describes the evolution of magnetohydrodynamic waves in the presence of collisional and charge exchange interactions of a partially ionized plasma. The partially ionized plasma consists of electrons, ions and a significant number of neutral atoms. In our model, the electrons and ions are described by a single fluid compressible magnetohydrodynamic (MHD) model and are coupled self-consistently to the neutral gas, described by the compressible hydrodynamic equations. Both the plasma and neutral fluids are treated with different energy equations that describe thermal energy exchange processes between them. Based on our self-consistent model, we find that propagating Alfv\\'enic and fast/slow modes grow and damp alternately through a nonlinear modulation process. The modulation appears to be robust and survives strong damping by the neutral component.
Lu, Y.; Cottone, F.; Boisseau, S.; Galayko, D.; Marty, F.; Basset, P.
2015-12-01
This paper reports for the first time a MEMS electrostatic vibration energy harvester (e-VEH) with corona-charged vertical electrets on its electrodes. The bandwidth of the 1-cm2 device is extended in low and high frequencies by nonlinear elastic stoppers. With a bias voltage of 46 V (electret@21 V + DC external source@25 V) between the electrodes, the RMS power of the device reaches 0.89 μW at 33 Hz and 6.6 μW at 428 Hz. The -3dB frequency band including the hysteresis is 223∼432 Hz, the one excluding the hysteresis 88∼166 Hz. We also demonstrate the charging of a 47 μF capacitor used for powering a wireless and autonomous temperature sensor node with a data transmission beyond 10 m at 868 MHz.
Generalized demonstration of Ramo's theorem with space charge and polarization effects
Hamel, Louis-André; Julien, Manuel
2008-12-01
Ramo's theorem provides a convenient way of simulating the currents induced through the electrodes of a radiation detector by the movement of charge carriers. The concept of weighting potential or of weighting field is the key ingredient in the calculation of the induced currents. A new demonstration of the theorem, based on energy balance, is provided that explicitly takes into account the effect of material polarization. It is shown that Ramo's theorem is valid in an arbitrary linear material and that polarization charges at interfaces between different materials or in the bulk of inhomogeneous materials must be included in calculating the weighting potentials. The use of our definition of weighting potential is also demonstrated for non-linear materials. The present proof is thus more generally valid than previous ones.
Ion Compensation for Space Charge in the Helical Electron Beams of Gyrotrons
Manuilov, V. N.; Semenov, V. E.
2016-06-01
We solve analytically the problem about ion compensation for the space charge of a helical electron beam in a gyrotron operated in the long-pulse regime. Elementary processes, which take place during ionization of residual gas in the tube under typical pressures of 10-6-10-7 mm Hg, are considered. It is shown that distribution of the space charge is affected mainly by the electrons of the initial beam and slow-moving ions produced by ionization of the residual gas. Steady-state density of ions in the operating space of the gyrotron after the end of the transitional processes is found, as well as the electron density profile in the channel of electron beam transportation. The results obtained allow us to evaluate the pitch-factor variations caused by partial compensations for the potential "sagging" in the gyrotron cavity, thus being useful for analysis of starting currents, efficiency, and mode competition in high-power gyrotrons.
Scalar Perturbations on the background of Linearly and Nonlinearly Charged BTZ Black Holes
Tang, Zi-Yu; Zangeneh, Mahdi Kord; Wang, Bin; Saavedra, Joel
2016-01-01
We investigate the spacetime properties of BTZ black holes in Maxwell field and BornInfeld field and find rich properties in the spacetime structures when the model parameters vary. Employing the Landau-Lifshitz theory, we examine the thermodynamical phase transition in the charged BTZ holes. We further study the dynamical perturbation in the background of the charged BTZ black holes and find different properties of dynamical perturbations for the extreme and nonextreme charged BTZ black holes, which can serve as a new physical signal to indicate the phase transition between them.
Gilardoni, S S; Martini, M; Métral, E; Steerenberg, R; Müller, A-S
2006-01-01
Recently, a novel technique to perform multi-turn extraction from a circular particle accelerator was proposed. It is based on beam splitting and trapping, induced by a slow crossing of a nonlinear resonance, inside stable islands of transverse phase space. Experiments at the CERN Proton Synchrotron started in 2002 and evidence of beam splitting was obtained by summer 2004. In this paper the measurement results achieved with both a low- and a high-intensity, single-bunch proton beam are presented.
Dyja, Robert; van der Zee, Kristoffer G
2016-01-01
We present an adaptive methodology for the solution of (linear and) non-linear time dependent problems that is especially tailored for massively parallel computations. The basic concept is to solve for large blocks of space-time unknowns instead of marching sequentially in time. The methodology is a combination of a computationally efficient implementation of a parallel-in-space-time finite element solver coupled with a posteriori space-time error estimates and a parallel mesh generator. This methodology enables, in principle, simultaneous adaptivity in both space and time (within the block) domains. We explore this basic concept in the context of a variety of time-steppers including $\\Theta$-schemes and Backward Differentiate Formulas. We specifically illustrate this framework with applications involving time dependent linear, quasi-linear and semi-linear diffusion equations. We focus on investigating how the coupled space-time refinement indicators for this class of problems affect spatial adaptivity. Final...
Energy Technology Data Exchange (ETDEWEB)
Reshak, A.H. [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Khan, Wilayat, E-mail: walayat76@gmail.com [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)
2014-04-01
Highlights: • FP-LAPW technique is used for calculating the electronic structure. • The band structure shows that the calculated compound is semiconductor. • The complex dielectric function has been calculated. • Nonlinear optical properties has also been calculated. • This compound can be used for molecular engineering of the crystals. - Abstract: Self-consistent calculations is performed using the full potential linear augmented plane wave (FP-LAPW) technique based on density functional theory (DFT) to investigate the electronic band structure, density of states, electronic charge density, linear and non-linear optical properties of α-LiAlTe{sub 2} compound having tetragonal symmetry with space group I4{sup ¯}2d. The electronic structure are calculated using the Ceperley Alder local density approach (CA-LDA), Perdew Burke and Ernzerhof generalize gradient approach (PBE-GGA), Engel–Vosko generalize gradient approach (EVGGA) and modified Becke Johnson approach (mBJ). Band structure calculations of (α-LiAlTe{sub 2}) depict semiconducting nature with direct band gap of 2.35 eV (LDA), 2.48 eV (GGA), 3.05 eV (EVGGA) and 3.13 eV (mBJ), which is comparable to experimental value. The calculated electronic charge density show ionic interaction between Te and Li atoms and polar covalent interaction between Al and Te atoms. Some optical susceptibilities like dielectric constants, refractive index, extension co-efficient, reflectivity and energy loss function have been calculated and analyzed on the basis of electronic structure. The compound α-LiAlTe{sub 2} provides a considerable negative value of birefringence of −0.01. Any anisotropy observed in the linear optical properties which are in favor to enhance the nonlinear optical properties. The symbol χ{sub abc}{sup (2)}(ω) represents the second order nonlinear optical susceptibilities, possess six non-zero components in this symmetry (tetragonal), called: 1 2 3, 2 1 3, 2 3 1, 1 3 2, 3 1 2 and 3 2 1
Deliktaş, Ekin; Teymür, Mevlüt
2017-07-01
In this study, the propagation of shear horizontal (SH) waves in a nonlinear elastic half space covered by a nonlinear elastic layer with a slowly varying interface is examined. The constituent materials are assumed to be homogenous, isotropic, elastic and having different mechanical properties. By employing the method of multiple scales, a nonlinear Schrödinger equation (NLS) with variable coefficients is derived for the nonlinear self-modulation of SH waves. We examine the effects of dispersion, irregularity of the interface and nonlinearity on the propagation characteristics of SH waves.
Evaluation of Radiation Belt Space Weather Forecasts for Internal Charging Analyses
Minow, Joseph I.; Coffey, Victoria N.; Jun, Insoo; Garrett, Henry B.
2007-01-01
A variety of static electron radiation belt models, space weather prediction tools, and energetic electron datasets are used by spacecraft designers and operations support personnel as internal charging code inputs to evaluate electrostatic discharge risks in space systems due to exposure to relativistic electron environments. Evaluating the environment inputs is often accomplished by comparing whether the data set or forecast tool reliability predicts measured electron flux (or fluence over a given period) for some chosen period. While this technique is useful as a model metric, it does not provide the information necessary to evaluate whether short term deviances of the predicted flux is important in the charging evaluations. In this paper, we use a 1-D internal charging model to compute electric fields generated in insulating materials as a function of time when exposed to relativistic electrons in the Earth's magnetosphere. The resulting fields are assumed to represent the "true" electric fields and are compared with electric field values computed from relativistic electron environments derived from a variety of space environment and forecast tools. Deviances in predicted fields compared to the "true" fields which depend on insulator charging time constants will be evaluated as a potential metric for determining the importance of predicted and measured relativistic electron flux deviations over a range of time scales.
Analytical theory of the space-charge region of lateral p-n junctions in nanofilms
Energy Technology Data Exchange (ETDEWEB)
Gurugubelli, Vijaya Kumar, E-mail: vkgurugubelli@gmail.com; Karmalkar, Shreepad [Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India)
2015-07-21
There is growing interest in fabricating conventional semiconductor devices in a nanofilm which could be a 3D material with one reduced dimension (e.g., silicon-on-insulator (SOI) film), or single/multiple layers of a 2D material (e.g., MoS{sub 2}), or a two dimensional electron gas/two dimensional hole gas (2DEG/2DHG) layer. Lateral p-n junctions are essential parts of these devices. The space-charge region electrostatics in these nanofilm junctions is strongly affected by the surrounding field, unlike in bulk junctions. Current device physics of nanofilms lacks a simple analytical theory of this 2D electrostatics of lateral p-n junctions. We present such a theory taking into account the film's thickness, permittivity, doping, interface charge, and possibly different ambient permittivities on film's either side. In analogy to the textbook theory of the 1D electrostatics of bulk p-n junctions, our theory yields simple formulas for the depletion width, the extent of space-charge tails beyond this width, and the screening length associated with the space-charge layer in nanofilm junctions; these formulas agree with numerical simulations and measurements. Our theory introduces an electrostatic thickness index to classify nanofilms into sheets, bulk and intermediate sized.
Directory of Open Access Journals (Sweden)
Esfandiar, H.
2013-05-01
Full Text Available In this paper, based on the VoigtKelvin constitutive model, nonlinear dynamic modelling and state space representation of a viscoelastic beam acting as a flexible robotic manipulator is investigated. Complete nonlinear dynamic modelling of a viscoelastic beam without premature linearisation of dynamic equations is developed. The adopted method is capable of reproducing nonlinear dynamic effects, such as beam stiffening due to centrifugal and Coriolis forces induced by rotation of the joints. Structural damping effects on the models dynamic behaviour are also shown. A reliable model for a viscoelastic beam is subsequently presented. The governing equations of motion are derived using Hamiltons principle, and using the finite difference method, nonlinear partial differential equations are reduced to ordinary differential equations. For the purpose of flexible manipulator control, the standard form of state space equations for the viscoelastic link and the actuator is obtained. Simulation results indicate substantial improvements in dynamic behaviour, and a parameter sensitivity study is carried out to investigate the effect of structural damping on the vibration amplitude.
Nonlinear free vibrations of beams in space due to internal resonance
Stoykov, S.; Ribeiro, P.
2011-08-01
The geometrically nonlinear free vibrations of beams with rectangular cross section are investigated using a p-version finite element method. The beams may vibrate in space, hence they may experience longitudinal, torsional and non-planar bending deformations. The model is based on Timoshenko's theory for bending and assumes that, under torsion, the cross section rotates as a rigid body and is free to warp in the longitudinal direction, as in Saint-Venant's theory. The geometrical nonlinearity is taken into account by considering Green's nonlinear strain tensor. Isotropic and elastic beams are investigated and generalised Hooke's law is used. The equation of motion is derived by the principle of virtual work. Mostly clamped-clamped beams are investigated, although other boundary conditions are considered for validation purposes. Employing the harmonic balance method, the differential equations of motion are converted into a nonlinear algebraic form and then solved by a continuation method. One constant term, odd and even harmonics are assumed in the Fourier series and convergence with the number of harmonics is analysed. The variation of the amplitude of vibration with the frequency of vibration is determined and presented in the form of backbone curves. Coupling between modes is investigated, internal resonances are found and the ensuing multimodal oscillations are described. Some of the couplings discovered lead from planar oscillations to oscillations in the three dimensional space.
Aberration of a negative ion beam caused by space charge effect
Energy Technology Data Exchange (ETDEWEB)
Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Wada, S.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)
2010-02-15
Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.
Three-dimensional SCFT on conic space as hologram of charged topological black hole
Energy Technology Data Exchange (ETDEWEB)
Huang, Xing [School of Physics & Astronomy and Center for Theoretical Physics,Seoul National University, Seoul 151-747 (Korea, Republic of); Rey, Soo-Jong [School of Physics & Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Center for Quantum Space-Time, Sogang University,Seoul 121-742 (Korea, Republic of); Zhou, Yang [Center for Quantum Space-Time, Sogang University, Seoul 121-742 (Korea, Republic of)
2014-03-26
We construct three-dimensional N=2 supersymmetric field theories on conic spaces. Built upon the fact that the partition function depends solely on the Reeb vector of the Killing vector, we propose that holographic dual of these theories are four-dimensional, supersymmetric charged topological black holes. With the supersymmetry localization technique, we study conserved supercharges, free energy, and supersymmetric Rényi entropy. At planar large N limit, we demonstrate perfect agreement between the superconformal field theories and the supersymmetric charged topological black holes.
Huang, Xing; Zhou, Yang
2014-01-01
We construct three-dimensional N=2 supersymmetric conformal field theories on conic spaces. Built upon the fact that the partition function depends solely on the Reeb vector of the Killing vector, we propose that holographic dual of these theories are four-dimensional, supersymmetric charged topological black holes. With the supersymmetry localization technique, we study conserved supercharges, free energy, and Renyi entropy. At planar large N limit, we demonstrate perfect agreement between the superconformal field theories and the supersymmetric charged topological black holes.
Energy Technology Data Exchange (ETDEWEB)
Dijkstra, Arend G., E-mail: arend.dijkstra@mpsd.mpg.de, E-mail: tanimura@kuchem.kyoto-u.ac.jp [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); Tanimura, Yoshitaka, E-mail: arend.dijkstra@mpsd.mpg.de, E-mail: tanimura@kuchem.kyoto-u.ac.jp [Department of Chemistry, Kyoto University, Kyoto (Japan)
2015-06-07
We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods.
Dijkstra, Arend G; Tanimura, Yoshitaka
2015-06-01
We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods.
Chen, Guangye
2013-01-01
A recent proof-of-principle study proposes a nonlinear electrostatic implicit particle-in-cell (PIC) algorithm in one dimension (Chen, Chacon, Barnes, J. Comput. Phys. 230 (2011) 7018). The algorithm employs a kinetically enslaved Jacobian-free Newton-Krylov (JFNK) method, and conserves energy and charge to numerical round-off. In this study, we generalize the method to electromagnetic simulations in 1D using the Darwin approximation of Maxwell's equations, which avoids radiative aliasing noise issues by ordering out the light wave. An implicit, orbit-averaged time-space-centered finite difference scheme is applied to both the 1D Darwin field equations (in potential form) and the 1D-3V particle orbit equations to produce a discrete system that remains exactly charge- and energy-conserving. Furthermore, enabled by the implicit Darwin equations, exact conservation of the canonical momentum per particle in any ignorable direction is enforced via a suitable scattering rule for the magnetic field. Several 1D numer...
An Inhomogeneous Space-Time Patching Model Based on a Nonlocal and Nonlinear Schrodinger Equation
Dantas, Christine C
2016-01-01
We consider an integrable, nonlocal and nonlinear, Schr\\"odinger equation (NNSE) as a model for building space-time patchings in inhomogeneous loop quantum cosmology (LQC). We briefly review exact solutions of the NNSE, specially those obtained through "geometric equivalence" methods. Furthemore, we argue that the integrability of the NNSE could be linked to consistency conditions derived from LQC, under the assumption that the patchwork dynamics behaves as an integrable many-body system.
Non-linear shape functions over time in the space-time finite element method
Directory of Open Access Journals (Sweden)
Kacprzyk Zbigniew
2017-01-01
Full Text Available This work presents a generalisation of the space-time finite element method proposed by Kączkowski in his seminal of 1970’s and early 1980’s works. Kączkowski used linear shape functions in time. The recurrence formula obtained by Kączkowski was conditionally stable. In this paper, non-linear shape functions in time are proposed.
Numerical Simulations for the Space-Time Variable Order Nonlinear Fractional Wave Equation
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Nasser Hassan Sweilam
2013-01-01
Full Text Available The explicit finite-difference method for solving variable order fractional space-time wave equation with a nonlinear source term is considered. The concept of variable order fractional derivative is considered in the sense of Caputo. The stability analysis and the truncation error of the method are discussed. To demonstrate the effectiveness of the method, some numerical test examples are presented.
On the System of Nonlinear Mixed Implicit Equilibrium Problems in Hilbert Spaces
Directory of Open Access Journals (Sweden)
Yeol Je Cho
2010-01-01
Full Text Available We use the Wiener-Hopf equations and the Yosida approximation notions to prove the existence theorem of a system of nonlinear mixed implicit equilibrium problems (SMIE in Hilbert spaces. The algorithm for finding a solution of the problem (SMIE is suggested; the convergence criteria and stability of the iterative algorithm are discussed. The results presented in this paper are more general and are viewed as an extension, refinement, and improvement of the previously known results in the literature.
GLOBAL SOLUTIONS OF SYSTEMS OF NONLINEAR IMPULSIVE VOLTERRA INTEGRAL EQUATIONS IN BANACH SPACES
Institute of Scientific and Technical Information of China (English)
陈芳启; 陈予恕
2001-01-01
The existence of solutions for systems of nonlinear impulsive Volterra integral equations on the infinite interval R+ with an infinite number of moments of impulse effect in Banach spaces is studied. Some existence theorems of extremal solutions are obtained,which extend the related results for this class of equations on a finite interval with a finite number of moments of impulse effect. The results are demonstrated by means of an example of an infinite systems for impulsive integral equations.
Brane charges and Chern Simons invariants of hyperbolic spaces, with cosmological applications
Bytsenko, Andrei A.; Elizalde, Emilio
2006-05-01
We discuss methods of K-theory associated with hyperbolic orbifolds and valid for the description of Chern morphisms and brane charges. Such methods of K-theory are applied to compute D-brane charges, which are identified with elements of Grothendick K-groups, and for manifolds with horizons, spaces that naturally arise as the near-horizon of black brane geometries. In de Sitter spaces, these solutions break supersymmetry, and do not describe universes with zero cosmological constant. Here we pay attention to real hyperbolic spaces, and we examine associated Chern classes and brane charges using methods of K-theory and spectral theory of differential operators related to real hyperbolic spaces. An argument in favour of hyperbolic geometries in the treatment of the contributions to the vacuum persistence amplitude in QFT is given. All those are to be viewed as the proper mathematical structures underlying QFT with relevant backgrounds and boundary conditions in string cosmology. Invited contribution to the 7th Int. Workshop on Quantum Field Theory under the Influence of External Conditions, QFEXT'05 (Barcelona, 5 9 Sept. 2005).
Directory of Open Access Journals (Sweden)
M. Boudjema
2003-01-01
Full Text Available The elastic response of many rocks to quasistatic stress changes is highly nonlinear and hysteretic, displaying discrete memory. Rocks also display unusual nonlinear response to dynamic stress changes. A model to describe the elastic behavior of rocks and other consolidated materials is called the Preisach-Mayergoyz (PM space model. In contrast to the traditional analytic approach to stress-strain, the PM space picture establishes a relationship between the quasistatic data and a number density of hysteretic mesoscopic elastic elements in the rock. The number density allows us to make quantitative predictions of dynamic elastic properties. Using the PM space model, we analyze a complex suite of quasistatic stress-strain data taken on Berea sandstone. We predict a dynamic bulk modulus and a dynamic shear modulus surface as a function of mean stress and shear stress. Our predictions for the dynamic moduli compare favorably to moduli derived from time of flight measurements. We derive a set of nonlinear elastic constants and a set of constants that describe the hysteretic behavior of the sandstone.
Persistence of solutions to nonlinear evolution equations in weighted Sobolev spaces
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Xavier Carvajal Paredes
2010-11-01
Full Text Available In this article, we prove that the initial value problem associated with the Korteweg-de Vries equation is well-posed in weighted Sobolev spaces $mathcal{X}^{s,heta}$, for $s geq 2heta ge 2$ and the initial value problem associated with the nonlinear Schrodinger equation is well-posed in weighted Sobolev spaces $mathcal{X}^{s,heta}$, for $s geq heta geq 1$. Persistence property has been proved by approximation of the solutions and using a priori estimates.
A Fully Discrete Galerkin Method for a Nonlinear Space-Fractional Diffusion Equation
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Yunying Zheng
2011-01-01
Full Text Available The spatial transport process in fractal media is generally anomalous. The space-fractional advection-diffusion equation can be used to characterize such a process. In this paper, a fully discrete scheme is given for a type of nonlinear space-fractional anomalous advection-diffusion equation. In the spatial direction, we use the finite element method, and in the temporal direction, we use the modified Crank-Nicolson approximation. Here the fractional derivative indicates the Caputo derivative. The error estimate for the fully discrete scheme is derived. And the numerical examples are also included which are in line with the theoretical analysis.
Abdel-Salam, Emad A-B; Hassan, Gmal F
2015-01-01
In this paper, the fractional projective Riccati expansion method is proposed to solve fractional differential equations. To illustrate the effectiveness of the method, we discuss the space-time fractional Burgers equation, the space-time fractional mKdV equation and time fractional biological population model. The solutions are expressed in terms of fractional hyperbolic functions. These solutions are useful to understand the mechanisms of the complicated nonlinear physical phenomena and fractional differential equations. Among these solutions, some are found for the first time. The fractal index for the obtained results is equal to one. Counter examples to compute the fractal index are introduced in appendix.
Maj, Omar
2008-01-01
This is the second part of a work aimed to study complex-phase oscillatory solutions of nonlinear symmetric hyperbolic systems. We consider, in particular, the case of one space dimension. That is a remarkable case, since one can always satisfy the \\emph{naive} coherence condition on the complex phases, which is required in the construction of the approximate solution. Formally the theory applies also in several space dimensions, but the \\emph{naive} coherence condition appears to be too restrictive; the identification of the optimal coherence condition is still an open problem.
Ground State and Charge Renormalization in a Nonlinear Model of Relativistic Atoms
Gravejat, Philippe; Sere, Eric
2007-01-01
We study the reduced Bogoliubov-Dirac-Fock (BDF) energy which allows to describe relativistic electrons interacting with the Dirac sea, in an external electrostatic potential. The model can be seen as a mean-field approximation of Quantum Electrodynamics (QED) where photons and the so-called exchange term are neglected. A state of the system is described by its one-body density matrix, an infinite rank self-adjoint operator which is a compact perturbation of the negative spectral projector of the free Dirac operator (the Dirac sea). We study the minimization of the reduced BDF energy under a charge constraint. We prove the existence of minimizers for a large range of values of the charge, and any positive value of the coupling constant $\\alpha$. Our result covers neutral and positively charged molecules, provided that the positive charge is not large enough to create electron-positron pairs. We also prove that the density of any minimizer is an $L^1$ function and compute the effective charge of the system, re...
Küchler, Sebastian; Meurer, Thomas; Jacobs, Laurence J; Qu, Jianmin
2009-03-01
This study investigates two-dimensional wave propagation in an elastic half-space with quadratic nonlinearity. The problem is formulated as a hyperbolic system of conservation laws, which is solved numerically using a semi-discrete central scheme. These numerical results are then analyzed in the frequency domain to interpret the nonlinear effects, specifically the excitation of higher-order harmonics. To quantify and compare the nonlinearity of different materials, a new parameter is introduced, which is similar to the acoustic nonlinearity parameter beta for one-dimensional longitudinal waves. By using this new parameter, it is found that the nonlinear effects of a material depend on the point of observation in the half-space, both the angle and the distance to the excitation source. Furthermore it is illustrated that the third-order elastic constants have a linear effect on the acoustic nonlinearity of a material.
Institute of Scientific and Technical Information of China (English)
文双春; 范滇元
2002-01-01
Spatiotemporal instability in nonlinear dispersive media is investigated on the basis of the nonlinear envelope equation. A general expression for instability gain which includes the effects of space-time focusing, arbitrarily higher-order dispersions and self-steepening is obtained. It is found that, for both normal and anomalous group-velocity dispersions, space-time focusing may lead to the appearance of new instability regions and influence the original instability gain spectra mainly by shrinking their regions. The region of the original instability gain spectrum shrinks much more in normal dispersion case than in anomalous one. In the former case, space-time focusing completely suppresses the growing of higher frequency components. In addition, we find that all the oddth-order dispersions contribute none to instability, while all the eventh-order dispersions influence instability region and do not influence the maximum instability gain, therein the fourth-order dispersion plays the same role as space-time focusing in spatiotemporal instability. The main role played by self-steepening in spatiotemporal instability is that it reduces the instability gain and exerts much more significant influence on the new instability regions resulting from space-time focusing.
Noll, Daniel
2015-01-01
An electron lens is planned for the Fermilab Integrable Optics Test Accelerator as a nonlinear element for integrable dynamics, as an electron cooler, and as an electron trap to study space-charge compensation in rings. We present the main design principles and constraints for nonlinear integrable optics. A magnetic configuration of the solenoids and of the toroidal section is laid out. Single-particle tracking is used to optimize the electron path. Electron beam dynamics at high intensity is calculated with a particle-in-cell code to estimate current limits, profile distortions, and the effects on the circulating beam. In the conclusions, we summarize the main findings and list directions for further work.
Directory of Open Access Journals (Sweden)
Cristina Stancu
2009-10-01
Full Text Available A computation method of the electricfield and ionic space charge density in planeinsulations with water trees (using a ComsolMultiphysics software and the thermal step currents(Im(t measured with Thermal Step Method ispresented. A parabolic spatial variation of volumecharge density, an exponential spatial variation ofthe electric permittivity ε and a linear dependency ofε and the temperature coefficient of permittivity αεwith the average water concentration in trees, areconsidered. For a water tree with a known length,different values of charge density are consideredand the electric field and the thermal step currentsIc(t are calculated. The currents Ic(t and Im(t arecompared and the volume of charge density andelectric field for which Ic(t is identical with Im(t arekept.
Field and temperature dependence of space charge injection in a silicone rubber
Rain, P.; Nguyen, D. H.; Sylvestre, A.; Rowe, S.
2009-12-01
The generation of space charges in a silicone elastomer has been characterized under dc voltage as a function of the temperature using the laser induced pressure pulse (LIPP) method. The analysis of the LIPP spectra has been detailed thanks to acoustical considerations, taking into account the reflection, attenuation and dispersion of the pressure wave. Both heterocharges and homocharges have been observed depending on the field magnitude (5 to 20 × 106 V m-1), polarization duration and temperature (20, 40 or 60 °C). With temperature increasing, charges are observed at lower fields. Heterocharges appear in less stressed conditions. Then, homocharges take the place of these heterocharges. Positive homocharges are observed in lower stressed conditions than negative homocharges. Mobility of these charges has not been observed below 60 °C.
Non-linear diffusion in RD and in Hilbert Spaces, a Cylindrical/Functional Integral Study
Botelho, Luiz Carlos Lobato
2010-01-01
We present a proof for the existence and uniqueness of weak solutions for a cut-off and non cut-off model of non-linear diffusion equation in finite-dimensional space RD useful for modelling flows on porous medium with saturation, turbulent advection, etc. - and subject to deterministic or stochastic (white noise) stirrings. In order to achieve such goal, we use the powerful results of compacity on functional Lp spaces (the Aubin-Lion Theorem). We use such results to write a path-integral solution for this problem. Additionally, we present the rigourous functional integral solutions for the Linear Diffussion equation defined in Infinite-Dimensional Spaces (Separable Hilbert Spaces). These further results are presented in order to be useful to understand Polymer cylindrical surfaces probability distributions and functionals on String theory.
Contamination and Radiation Effects on Nonlinear Crystals for Space Laser Systems
Abdeldayem, Hossain A.; Dowdye, Edward; Jamison, Tracee; Canham, John; Jaeger, Todd
2005-01-01
Space Lasers are vital tools for NASA s space missions and military applications. Although, lasers are highly reliable on the ground, several past space laser missions proved to be short-lived and unreliable. In this communication, we are shedding more light on the contamination and radiation issues, which are the most common causes for optical damages and laser failures in space. At first, we will present results based on the study of liquids and subsequently correlate these results to the particulates of the laser system environment. We present a model explaining how the laser beam traps contaminants against the optical surfaces and cause optical damages and the role of gravity in the process. We also report the results of the second harmonic generation efficiency for nonlinear optical crystals irradiated with high-energy beams of protons. In addition, we are proposing to employ the technique of adsorption to minimize the presence of adsorbing molecules present in the laser compartment.
The electric vehicle routing problem with non-linear charging functions
2015-01-01
International audience; The use of electric vehicles (EVs) in freight and passenger transportation gives birth to a new family of vehicle routing problems (VRPs), the so-called electric VRPs (e-VRPs). As their name suggests, e-VRPs extend classical VRPs to account (mainly) for two constraining EV features: the short driving range and the long battery charging time. As a matter of fact, routes performed by EVs usually need to include time-consuming detours to charging stations. Most of the exi...
Charge quantization and the Standard Model from the CP2 and CP3 nonlinear σ-models
Hellerman, Simeon; Kehayias, John; Yanagida, Tsutomu T.
2014-04-01
We investigate charge quantization in the Standard Model (SM) through a CP2 nonlinear sigma model (NLSM), SU(3/(SU(2×U(1), and a CP3 model, SU(4/(SU(3×U(1). We also generalize to any CPk model. Charge quantization follows from the consistency and dynamics of the NLSM, without a monopole or Grand Unified Theory, as shown in our earlier work on the CP1 model (arXiv:1309.0692). We find that representations of the matter fields under the unbroken non-abelian subgroup dictate their charge quantization under the U(1 factor. In the CP2 model the unbroken group is identified with the weak and hypercharge groups of the SM, and the Nambu-Goldstone boson (NGB) has the quantum numbers of a SM Higgs. There is the intriguing possibility of a connection with the vanishing of the Higgs self-coupling at the Planck scale. Interestingly, with some minor assumptions (no vector-like matter and minimal representations) and starting with a single quark doublet, anomaly cancellation requires the matter structure of a generation in the SM. Similar analysis holds in the CP3 model, with the unbroken group identified with QCD and hypercharge, and the NGB having the up quark as a partner in a supersymmetric model. This can motivate solving the strong CP problem with a vanishing up quark mass.
Application of Gauss's law space-charge limited emission model in iterative particle tracking method
Altsybeyev, V. V.; Ponomarev, V. A.
2016-11-01
The particle tracking method with a so-called gun iteration for modeling the space charge is discussed in the following paper. We suggest to apply the emission model based on the Gauss's law for the calculation of the space charge limited current density distribution using considered method. Based on the presented emission model we have developed a numerical algorithm for this calculations. This approach allows us to perform accurate and low time consumpting numerical simulations for different vacuum sources with the curved emitting surfaces and also in the presence of additional physical effects such as bipolar flows and backscattered electrons. The results of the simulations of the cylindrical diode and diode with elliptical emitter with the use of axysimmetric coordinates are presented. The high efficiency and accuracy of the suggested approach are confirmed by the obtained results and comparisons with the analytical solutions.
Space charge saturated sheath regime and electron temperature saturation in Hall thrusters
Raitses, Y.; Staack, D.; Smirnov, A.; Fisch, N. J.
2005-07-01
Existing electron-wall interaction models predict that secondary electron emission in Hall thrusters is significant and that the near-wall sheaths are space charge saturated. The experimental electron-wall collision frequency is computed using plasma parameters measured in a laboratory Hall thruster. In spite of qualitative similarities between the measured and predicted dependencies of the maximum electron temperature on the discharge voltage, the deduced electron-wall collision frequency for high discharge voltages is much lower than the theoretical value obtained for space charge saturated sheath regime, but larger than the wall recombination frequency. The observed electron temperature saturation appears to be directly associated with a decrease of the Joule heating rather than with the enhancement of the electron energy loss at the walls due to a strong secondary electron emission. Another interesting experimental result is related to the near-field plasma plume, where electron energy balance appears to be independent on the magnetic field.
Phase transition in extended thermodynamic phase space and charged Horava-Lifshitz black holes
Poshteh, Mohammad Bagher Jahani
2016-01-01
For charged black holes in Horava-Lifshitz gravity, it is shown that a second order phase transition takes place in extended phase space. We study the behavior of specific heat and free energy at the point of transition in canonical and grand canonical ensembles and show that the black hole falls into a state which is locally and globally stable. We relate the second order nature of phase transition to the fact that the phase transition occurs at a sharp temperature and not over a temperature interval. By taking cosmological constant as thermodynamic pressure for charged black holes, we extend Ehrenfest's equations. We obtain nine equations and show that, all of them are satisfied at the point in which the specific heat diverges. We also apply geometrothermodynamics to extended phase space and show that the scalar curvature of Quevedo metric diverges at the point at which the second order phase transition takes place.
Single bunch transverse instability in a circular accelerator with chromaticity and space charge
Balbekov, V
2015-01-01
Transverse instability of a bunch in a circular accelerator is elaborated in this paper. New tree-modes model is proposed and developed to describe the most unstable modes of the bunch. The model includes chromaticity and space charge, and can be used with any bunch and wake forms. Dispersion relation for the bunch eigentunes is obtained in form of a third-order algebraic equation. Known head-tail and TMCI modes appear as the ultimate cases which are distinctly bounded at zero chromaticity only. It is shown that the instability parameters depend only slightly on the bunch model but are rather sensitive to the wake shape. Resistive wall wake is considered in detail including a comparison of single and collective effects. It is shown that space charge influence depends on sign of the wake function enhancing the stability with negative one.
The Influence of Pre-conditioning on Space Charge Formation in LDPE
DEFF Research Database (Denmark)
Henriksen, Mogens; Holbøll, Joachim T.; Fleming, R.J.
1998-01-01
at 80oC for 48 hrs in short-circuit at rotary pump pressure. Some were then cooled to 20oC, over a 6 hr period, still under rotary pump pressure and in short circuit, while others were cooled to 20oC in less than 5 minutes, in the laboratory air (still in short circuit). DC fields of 20 kV/mm were...... then applied at room temperature, and space charge accumulation was monitored as a function of time, using the pulsed-electro-acoustic (PEA) method (Denmark) and the laser-induced-pressure-pulse (LIPP) method (Australia). The space charge density was calibrated from measurements at fields up to 5 kV/mm, where...
Charging of small grains in a space plasma: Application to Jovian stream particles
Dzhanoev, A R; Liu, X; Spahn, F
2016-01-01
Most theoretical investigations of dust charging processes in space have treated the current balance condition as independent of grain size. However, for small grains, as they are often observed in space environments, a dependence on grain size is expected due to secondary electron emission (SEE). Here, by the term "small" we mean a particle size comparable to the typical penetration depth for given primary electron energy. The results are relevant for the dynamics of small, charged dust particles emitted by the volcanic moon Io, which form the Jovian dust streams. We revise the theory of charging of small (sub-micron sized) micrometeoroids to take into account a high production of secondary electrons for small grains immersed in an isotropic flux of electrons. We apply our model to obtain an improved estimate for the charge of the dust streams leaving the Jovian system, detected by several spacecraft. For the Jupiter plasma environment we derive the surface potential of grains composed of NaCl (believed to b...
Geometrical method for thermal instability of nonlinearly charged BTZ Black Holes
Hendi, Seyed Hossein; Panah, Behzad Eslam
2015-01-01
In this paper we consider three dimensional BTZ black holes with three models of nonlinear electrodynamics as source. Calculating heat capacity, we study the stability and phase transitions of these black holes. We show that Maxwell, logarithmic and exponential theories yield only type one phase transition which is related to the root(s) of heat capacity. Whereas for correction form of nonlinear electrodynamics, heat capacity contains two roots and one divergence point. Next, we use geometrical approach for studying classical thermodynamical behavior of the system. We show that Weinhold and Ruppeiner metrics fail to provide fruitful results and the consequences of the Quevedo approach are not completely matched to the heat capacity results. Then, we employ a new metric for solving this problem. We show that this approach is successful and all divergencies of its Ricci scalar and phase transition points coincide. We also show that there is no phase transition for uncharged BTZ black holes.
Space Charge Saturated Sheath Regime and Electron Temperature Saturation in Hall Thrusters
Energy Technology Data Exchange (ETDEWEB)
Y. Raitses; D. Staack; A. Smirnov; N.J. Fisch
2005-03-16
Secondary electron emission in Hall thrusters is predicted to lead to space charge saturated wall sheaths resulting in enhanced power losses in the thruster channel. Analysis of experimentally obtained electron-wall collision frequency suggests that the electron temperature saturation, which occurs at high discharge voltages, appears to be caused by a decrease of the Joule heating rather than by the enhancement of the electron energy loss at the walls due to a strong secondary electron emission.
Breaking the Space Charge Limit in Organic Solar Cells by a Novel Plasmonic-Electrical Concept
Sha, Wei E. I.; Xuanhua Li; Choy, Wallace C. H.
2014-01-01
As a fundamental electrostatic limit, space charge limit (SCL) for photocurrent is a universal phenomenon and of paramount importance for organic semiconductors with unbalanced photocarriers mobility and high exciton generation. Here we proposed a new plasmonic-electrical concept to manipulate electrical properties of organic devices including photocarriers recombination, transport and collection. As a proof-of-concept, organic solar cells (OSCs) comprising metallic planar and grating electro...
Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect
Energy Technology Data Exchange (ETDEWEB)
Lee, Myoung-Jae [Department of Physics and Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588, South Korea and Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States)
2016-09-15
The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order. It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.
Phase modulation spectroscopy of space-charge wave resonances in Bi12SiO20
DEFF Research Database (Denmark)
Vasnetsov, M.; Buchhave, Preben; Lyuksyutov, S.
1997-01-01
A new experimental method for the study of resonance effects and space-charge wave excitation in photorefractive Bi12SiO20 crystals by using a combination of frequency detuning and phase modulation technique has been developed. The accuracy of the method allows a detection of resonance peaks...... and revealed its resonance dependence. A minimum of electric current through the sample corresponds to the main resonance detected by phase modulation technique....
Dispersion Matching of a Space Charge dominated Beam at Injection into the CERN PS Booster
Hanke, Klaus; Scrivens, Richard
2005-01-01
In order to match the dispersion at injection into the CERN PS Booster, the optics of the injection line was simulated using two different codes (MAD and TRACE). The simulations were benchmarked versus experimental results. The model of the line was then used to re-match the dispersion. Experimental results are presented for different optics of the line. Measurements with varying beam current show the independence of the measured quantity of space-charge effects.
Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect
Lee, Myoung-Jae; Jung, Young-Dae
2016-09-01
The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order. It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.
Grain boundary defect chemistry of acceptor-doped titanates: Space charge layer width
Energy Technology Data Exchange (ETDEWEB)
Vollman, M.; Waser, R. [Inst. fuer Werkstoffe der Elektrotechnik, Aachen (Germany)
1994-01-01
The grain boundary space charge depletion layers in acceptor-doped SrTiO{sub 3} ceramics were investigated by impedance spectroscopy in the time and frequency domain. Based on the layer and its dependence on the acceptor concentration, the temperature, and the oxygen partial pressure during annealing, a suggestion for a refined Schottky model is proposed. The local distribution of the donor type grain boundary states causing the depletion layer and the resulting band bending are discussed.
Longitudinal Space Charge Effects in the JLAB IR FEL SRF Linac
Hernandez-Garcia, Carlos; Behre, Chris; Benson, S V; Herman-Biallas, George; Boyce, James; Douglas, David; Dylla, Fred; Evans, Richard; Grippo, A; Gubeli, Joe; Hardy, David; Jordan, Kevin; Merminga, Lia; Neil, George; Preble, Joe; Shinn, Michelle D; Siggins, Tim; Walker, Richard; Williams, Gwyn; Yunn, Byung; Zhang, Shukui
2004-01-01
Observations of energy spread asymmetry when operating the Linac on either side of crest and longitudinal emittance growth have been confirmed by extending PARMELA simulations from the injector to the end of the first SRF Linac module. The asymmetry can be explained by the interaction of the accelerating electric field with that from longitudinal space charge effects within the electron bunch. This can be a major limitation to performance in FEL accelerators.
The deformed conifold as a geometry on the space of unit charge CP^1 lumps
Speight, J M
2001-01-01
The strong structural similarity between the deformed conifold of Candelas and de la Ossa (a noncompact Calabi-Yau manifold) and the moduli space of unit charge CP^1 lumps equipped with its L^2 metric is pointed out. This allows one to reinterpret certain recent results on D3 branes in terms of lump dynamics, and to deduce certain curvature properties of the deformed conifold.
ACCELERATORS: Emittance coupling driven by space charge in the CSNS linac
Yin, Xue-Jun; Fu, Shi-Nian; Peng, Jun
2009-09-01
In the conventional design of RF linacs, the bunched beams are not in thermal equilibrium. The space charge forces couple the particle motions between the transverse and the longitudinal directions. Furthermore it will cause the equipartitioning process which leads to emittance growth and halo formation. In the design of the China Spallation Neutron Source (CSNS) linac, three cases are investigated using the Hofmann stability charts. In this paper, we present the equipartitioning beam study of the CSNS Alvarez DTL linac.
Universality of ac conduction for generalized space-charge transport in ordered solids
Gommans, H. H. P.; Kemerink, M.; Schilders, W. H. A.
2005-10-01
On numerous nonmetallic systems, the ac conductivity is observed to follow an approximate power law behavior σ(ω)=ωs with 0Isard scaling law for an arbitrary temperature dependence of the mobility. Our results demonstrate that space-charge transport can lead to the commonly observed power law and scaling behaviors without incorporating disorder. Nevertheless, the implications of disorder are discussed and they are expected to increase the range over which the power law behavior extends.
Hao, Jian; Chen, George; Liao, R
2011-01-01
Oil-paper insulation system is widely used in power transformers and cables. Moisture is recognized to the ?enemy number one? for transformer insulation except for temperature [1]. Moisture is not only one of the most important factor which can accelerate the transformer paper insulation aging, but also has great effect on the dielectric properties of oil-paper insulation. In this paper, dielectric response and space charge behaviour of oil-paper insulation sample with three different moistur...
Energy Technology Data Exchange (ETDEWEB)
Carlsten, B.E.; Fazio, M.V.; Faehl, R.J.; Kwan, T.J.; Rickel, D.G.; Stringfield, R.M.
1992-01-01
We discuss basic Relativistic Klystron Amplifier physics. We show that in the intense space-charge regime the maximum power extraction does not coincide with the maximum harmonic bunching. In addition, we show that as the beam is bunched, the additional power stored in the Coulomb fields does not add significantly to the overall power extraction. Because of these effects, the power extraction at 1.3 GHz for a 500 kV, 5 kA beam with reasonable beam-to-wall spacing is limited to around 35%. 3 refs., 17 figs.
Yoon, Sangcheol; Park, Byoungchoo; Hwang, Inchan
2015-11-01
The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole-Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers.
Energy Technology Data Exchange (ETDEWEB)
Chekhov, L.O.
1985-12-01
Matrix nonlinear sigma models are discussed and the matrix nonlinear sigma model in the case of N x ..cap alpha..N rectangular matrices is considered. The authors show that in two-dimensional Euclidean space, the model is renormalizable with respect to ..cap alpha.. and 1/N. The fulfillment of the chirality identity is demonstrated in the operator expansion for the renormalized theory.
The transverse space-charge force in tri-gaussian distribution
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.; /Fermilab
2005-12-01
In tracking, the transverse space-charge force can be represented by changes in the horizontal and vertical divergences, {Delta}x{prime} and {Delta}y{prime} at many locations around the accelerator ring. In this note, they are going to list some formulas for {Delta}x{prime} and {delta}y{prime} arising from space-charge kicks when the beam is tri-Gaussian distributed. They will discuss separately a flat beam and a round beam. they are not interested in the situation when the emittance growth arising from space charge becomes too large and the shape of the beam becomes weird. For this reason, they can assume the bunch still retains its tri-Gaussian distribution, with its rms sizes {sigma}{sub x}, {sigma}{sub y}, and {sigma}{sub z} increasing by certain factors. Thus after each turn, {sigma}{sub x}, {sigma}{sub y}, and {sigma}{sub z} can be re-calculated.
The MicroBooNE Experiment and the Impact of Space Charge Effects
Mooney, Michael
2015-01-01
MicroBooNE is an experiment designed to both probe neutrino physics phenomena and develop the LArTPC (Liquid Argon Time Projection Chamber) detector technology. The MicroBooNE experiment, which began taking data this year, is the first large LArTPC detector in the U.S. This experiment is the beginning of a path of detectors (both on the surface and underground) envisioned for the U.S. SBL (Short-BaseLine) and LBL (Long-BaseLine) programs. In order to interpret the data from the experiments on the surface, the impact of space charge effects must be simulated and calibrated. The space charge effect is the build-up of slow-moving positive ions in a detector due to, for instance, ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacement in the reconstructed position of signal ionization electrons in LArTPC detectors. The LArTPC utilized in the MicroBooNE experiment is expected to be modestly impacted from the space charge effect, with the e...
The Influence of Pre-conditioning on Space Charge Formation in LDPE
DEFF Research Database (Denmark)
Henriksen, Mogens; Holbøll, Joachim T.; Fleming, R.J.
1998-01-01
The effect of thermal conditioning, at reduced pressure, on space charge accumulation in planar LDPE samples under DC stress has been investigated. The samples were 1.8 mm thick, including two 0.1 mm thick semicon electrodes, and they were conditioned prior to voltage application by being held...... at 80oC for 48 hrs in short-circuit at rotary pump pressure. Some were then cooled to 20oC, over a 6 hr period, still under rotary pump pressure and in short circuit, while others were cooled to 20oC in less than 5 minutes, in the laboratory air (still in short circuit). DC fields of 20 kV/mm were...... then applied at room temperature, and space charge accumulation was monitored as a function of time, using the pulsed-electro-acoustic (PEA) method (Denmark) and the laser-induced-pressure-pulse (LIPP) method (Australia). The space charge density was calibrated from measurements at fields up to 5 kV/mm, where...
Studies on space charge neutralization and emittance measurement of beam from microwave ion source
Energy Technology Data Exchange (ETDEWEB)
Misra, Anuraag; Goswami, A.; Sing Babu, P.; Srivastava, S.; Pandit, V. S., E-mail: pandit@vecc.gov.in, E-mail: vspandit12@gmail.com [Variable Energy Cyclotron Centre, 1-AF, Bidhannagar, Kolkata 700 064 (India)
2015-11-15
A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.
On compensating tune spread induced by space charge in bunched beams
Energy Technology Data Exchange (ETDEWEB)
Litvinenko V. N.; Wang, G.
2014-05-09
Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator, or, in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. Using a proper transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.
Brihaye, Y
2011-01-01
We study the stability of static as well as of rotating and charged black holes in (4+1)-dimensional Anti-de Sitter space-time which possess spherical horizon topology. We observe a non-linear instability related to the condensation of a charged, tachyonic scalar field and construct "hairy" black hole solutions of the full system of coupled Einstein, Maxwell and scalar field equations. We observe that the limiting solution for small horizon radius is either a hairy soliton solution or a singular solution that is not a regular extremal solution. Within the context of the gauge/gravity duality the condensation of the scalar field describes a holographic conductor/superconductor phase transition on the surface of a sphere.
Directory of Open Access Journals (Sweden)
Ruijin Liao
2015-08-01
Full Text Available The main insulation system in high-voltage direct current (HVDC transformer consists of oil-paper insulation. The formation of space charge in insulation paper is crucial for the dielectric strength. Unfortunately, space charge behavior changes because of the corrosive sulfur substance in oil. This paper presents the space charge behavior in insulation paper induced by copper sulfide generated by corrosive sulfur in insulation oil. Thermal aging tests of paper-wrapped copper strip called the pigtail model were conducted at 130 °C in laboratory. Scanning electron microscopy (SEM was used to observe the surface of copper and paper. Pulse electroacoustic (PEA and thermally stimulated current (TSC methods were used to obtain the space charge behavior in paper. Results showed that both maximum and total amount of space charge increased for the insulation paper contaminated by semi-conductor chemical substance copper sulfide. The space charge decay rate of contaminated paper was significantly enhanced after the polarization voltage was removed. The TSC results revealed that copper sulfide increased the trap density and lowered the shallow trap energy levels. These results contributed to charge transportation by de-trapping and trapping processes. This improved charge transportation could be the main reason for the decreased breakdown voltage of paper insulation material.
A Space-Time Finite Element Model for Design and Control Optimization of Nonlinear Dynamic Response
Directory of Open Access Journals (Sweden)
P.P. Moita
2008-01-01
Full Text Available A design and control sensitivity analysis and multicriteria optimization formulation is derived for flexible mechanical systems. This formulation is implemented in an optimum design code and it is applied to the nonlinear dynamic response. By extending the spatial domain to the space-time domain and treating the design variables as control variables that do not change with time, the design space is included in the control space. Thus, one can unify in one single formulation the problems of optimum design and optimal control. Structural dimensions as well as lumped damping and stiffness parameters plus control driven forces, are considered as decision variables. The dynamic response and its sensitivity with respect to the design and control variables are discretized via space-time finite elements, and are integrated at-once, as it is traditionally used for static response. The adjoint system approach is used to determine the design sensitivities. Design optimization numerical examples are performed. Nonlinear programming and optimality criteria may be used for the optimization process. A normalized weighted bound formulation is used to handle multicriteria problems.
Salient region detection Using Wasserstein distance measure based on nonlinear scale space
Zhu, Lei; Cao, Zhiguo
2013-10-01
Many existing bottom-up saliency detection methods measure the multi-scale local prominence by building the Gaussian scale space. As a kind of linear scale space, it is a natural representation of human perception. However the Gaussian filtering does not respect the boundaries of proto-objects and smooth both noises and details. In this paper, we compute the pixel level center-surround difference in a nonlinear scale space which makes blurring locally adaptive to the image regions. The nonlinear scale space is built by a efficient evolution techniques and extended to represent color images. In contrast to some widely used region-based measures, we represent feature statistics by multivariate normal distributions and compare them with the Wasserstein distance on l2 norm (W2 distance). From the perspective of visual organization in imaging, many priors are proved to be efficient in global consideration. In order to further precisely locate the proper salient object, we also use the background prior as a global cue to refine the obtained local saliency map. The experimental results show that our approach outperforms 5 recent state of the art saliency detection methods in terms of precision and recall on a newly published benchmark.
Improved Nonlinear Model of a Second-Order Charge-Pump Pll
Gillespie, Diarmaid; Kennedy, Michael Peter; Kolumbán, Géza
An improved model of a second-order Charge-Pump Phase-Locked Loop (CP-PLL) is proposed. An event-driven second-order CP-PLL o-model is further developed from that described by Hedayat [1]. This model is made practical by taking account of VCO overload. Transient simulations are shown which illustrate the nature of phase-locking.
Variational principle and a perturbative solution of non-linear string equations in curved space
Roshchupkin, S N
1999-01-01
String dynamics in a curved space-time is studied on the basis of an action functional including a small parameter of rescaled tension constant. A rescaled slow worldsheet time $T=\\epsilon\\tau$ is introduced, and general covariant non-linear string equation are derived. It is shown that in the first order of an $\\epsilon $-expansion these equations are reduced to the known equation for geodesic derivation but complemented by a string oscillatory term. These equations are solved for the de Sitter and Friedmann -Robertson-Walker spaces. The primary string constraints are found to be split into a chain of perturbative constraints and their conservation and consistency are proved. It is established that in the proposed realization of the perturbative approach the string dynamics in the de Sitter space is stable for a large Hubble constant $H
Miksovsky, J.; Raidl, A.
Time delays phase space reconstruction represents one of useful tools of nonlinear time series analysis, enabling number of applications. Its utilization requires the value of time delay to be known, as well as the value of embedding dimension. There are sev- eral methods how to estimate both these parameters. Typically, time delay is computed first, followed by embedding dimension. Our presented approach is slightly different - we reconstructed phase space for various combinations of mentioned parameters and used it for prediction by means of the nearest neighbours in the phase space. Then some measure of prediction's success was computed (correlation or RMSE, e.g.). The position of its global maximum (minimum) should indicate the suitable combination of time delay and embedding dimension. Several meteorological (particularly clima- tological) time series were used for the computations. We have also created a MS- Windows based program in order to implement this approach - its basic features will be presented as well.
Emittance growth due to static and radiative space charge forces in an electron bunch compressor
Talman, Richard; Malitsky, Nikolay; Stulle, Frank
2009-01-01
Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004)PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel , Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)NIMAER0168-900210.1016/S0168-9002(00)00729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]). All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance γx on beam width (as controlled by the lattice βx function) at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening , in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001), http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR). (ii) A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the 2004 FEL Conference, pp. 18
Systems of general nonlinear set-valued mixed variational inequalities problems in Hilbert spaces
Directory of Open Access Journals (Sweden)
Cho Yeol
2011-01-01
Full Text Available Abstract In this paper, the existing theorems and methods for finding solutions of systems of general nonlinear set-valued mixed variational inequalities problems in Hilbert spaces are studied. To overcome the difficulties, due to the presence of a proper convex lower semi-continuous function, φ and a mapping g, which appeared in the considered problem, we have used some applications of the resolvent operator technique. We would like to point out that although many authors have proved results for finding solutions of the systems of nonlinear set-valued (mixed variational inequalities problems, it is clear that it cannot be directly applied to the problems that we have considered in this paper because of φ and g. 2000 AMS Subject Classification: 47H05; 47H09; 47J25; 65J15.
Finite Element Solutions for the Space Fractional Diffusion Equation with a Nonlinear Source Term
Directory of Open Access Journals (Sweden)
Y. J. Choi
2012-01-01
Full Text Available We consider finite element Galerkin solutions for the space fractional diffusion equation with a nonlinear source term. Existence, stability, and order of convergence of approximate solutions for the backward Euler fully discrete scheme have been discussed as well as for the semidiscrete scheme. The analytical convergent orders are obtained as O(k+hγ˜, where γ˜ is a constant depending on the order of fractional derivative. Numerical computations are presented, which confirm the theoretical results when the equation has a linear source term. When the equation has a nonlinear source term, numerical results show that the diffusivity depends on the order of fractional derivative as we expect.
Nonlinear Superconducting Metamaterials in Free-Space at mm-wave Frequencies
Anlage, Steven; Zhang, Daimeng; Trepanier, Melissa; Mukhanov, Oleg; Delfanazari, K.; Savinov, V.; Zheludev, N.
2014-03-01
Superconducting metamaterials show the promise of low loss, compact size and extreme tunability and nonlinearity, allowing for new applications. Most demonstrations of these metamaterials have been conducted in waveguide geometries, either in co-planar form or three-dimensional single-conductor structures. Here we demonstrate for the first time a widely tunable superconducting metamaterial operating under the free-space illumination of a quasi-optical beam in the 100 GHz regime. The meta-atoms are Radio Frequency Superconducting QUantum Interference Devices (RF SQUIDs) that form compact self-resonant objects endowed with the nonlinearity of the Josephson effect. The metamaterial is tuned with dc magnetic flux, temperature and mm-wave power, and holds promise for a new generation of mm-wave agile devices. This work is supported by the NSF-GOALI and OISE programs through grant # ECCS-1158644, and CNAM.
Teyssedre, G.; Vu, T. T. N.; Laurent, C.
2015-12-01
Among features observed in polyethylene materials under relatively high field, space charge packets, consisting in a pulse of net charge that remains in the form of a pulse as it crosses the insulation, are repeatedly observed but without complete theory explaining their formation and propagation. Positive charge packets are more often reported, and the models based on negative differential mobility(NDM) for the transport of holes could account for some charge packets phenomenology. Conversely, NDM for electrons transport has never been reported so far. The present contribution reports space charge measurements by pulsed electroacoustic method on miniature cables that are model of HVDC cables. The measurements were realized at room temperature or with a temperature gradient of 10 °C through the insulation under DC fields on the order 30-60 kV/mm. Space charge results reveal systematic occurrence of a negative front of charges generated at the inner electrode that moves toward the outer electrode at the beginning of the polarization step. It is observed that the transit time of the front of negative charge increases, and therefore the mobility decreases, with the applied voltage. Further, the estimated mobility, in the range 10-14-10-13 m2 V-1 s-1 for the present results, increases when the temperature increases for the same condition of applied voltage. The features substantiate the hypothesis of negative differential mobility used for modelling space charge packets.
Forte, V; Carli, C; Martini, M; Metral, E; Mikulec, B; Schmidt, F; Molodozhentsev, A
2013-01-01
The CERN PS Booster (PSB) has the largest space charge tune spread in the LHC injector chain. As part of the LHC Injectors Upgrade (LIU) project, the machine will be upgraded. Space charge and resonances are serious is- sues for the good quality of the beam at injection energy. Consequently simulations are needed to track the beam in the machine taking into account space charge effects: PTC-ORBIT has been used as tracking code. This paper presents simulation results that are compared with mea-surements for machine performances evaluation and code- benchmarking purposes.
Directory of Open Access Journals (Sweden)
S. Gilardoni
2006-10-01
Full Text Available Recently, a novel technique to perform multiturn extraction from a circular particle accelerator was proposed. It is based on beam splitting and trapping, induced by a slow crossing of a nonlinear resonance, inside stable islands of transverse phase space. Experiments at the CERN Proton Synchrotron started in 2002 and evidence of beam splitting was obtained by summer 2004. In this paper, the measurement results achieved with both a low- and a high-intensity, single-bunch proton beam are presented.
Pan, Shuokai; Elliott, Stephen J; Teal, Paul D; Lineton, Ben
2015-06-01
Nonlinear models of the cochlea are best implemented in the time domain, but their computational demands usually limit the duration of the simulations that can reasonably be performed. This letter presents a modified state space method and its application to an example nonlinear one-dimensional transmission-line cochlear model. The sparsity pattern of the individual matrices for this alternative formulation allows the use of significantly faster numerical algorithms. Combined with a more efficient implementation of the saturating nonlinearity, the computational speed of this modified state space method is more than 40 times faster than that of the original formulation.
磁绝缘线振荡器中空间电荷的调制%Modulation of the space charge in MILO
Institute of Scientific and Technical Information of China (English)
丁武
2001-01-01
In this paper, modulation of the space charge in a magnetically insulated transmission line oscillator (MILO) caused by the radio-frequency field (including the radiation wave field and the space charge wave field) is researched at first. Formula of the first order component of the harmonic current at saturation (nonlinear regime) is obtained. When the space charge wave is considered, it will enhance the harmonic current on condition that the signal is small and the radiation wave is in phase with the space charge wave, but the case is not certain with a large signal. The harmonic current will enhance with the increasing of the voltage on the diode and reduce with the increasing of the operating frequency and the saturation length.%首次研究了磁绝缘线振荡器中射频场(包括辐射波场和空间电荷波场)对空间电荷的调制，得到了在饱和时谐波电流一阶分量的公式。这个公式表明：考虑空间电荷波时，在小信号和辐射波与空间电荷波同相的条件下，它将增强谐波电流。在大信号时，情况不确定；谐波电流一阶分量将随二极管上电压的增加而增加，随运行频率和饱和长度的增加而减小
Moving Space Charge Field Effects in Photoconductive Semiconductors and Their Applications.
Wang, Chen-Chia
1995-01-01
Internal electric space charge fields are formed inside photoconductive semiconductors when they are illuminated by an optical interference pattern. This Thesis focuses on the effects of such space charge fields formed inside semiconductor materials which contain both donors and deep level traps for photo-excited charge carriers. The photon energies are less than the band gap of the photoconductive semiconductor. The space charge field arises from the migration of photo-excited charges from the brighter to darker regions of the optical interference pattern where they become trapped. If the center frequencies of the two mutually coherent optical fields which form the interference pattern are unequal, the interference pattern and consequently the internal space charge field move with identical velocity. The moving space charge field results in a net photocurrent output from the material even when no external electric bias field is present. The short-circuit photocurrents contain a wealth of information about the material characteristics of the photoconductive semiconductor which, once known, can be used to deduce information about the optical frequency spectrum of the optical fields which form the interference pattern. An approximate but very accurate mathematical characterization of the short-circuit photocurrents and their properties are presented. These properties were verified by direct experimental measurements performed in the photoconductive semiconductors InP:Fe, GaAs, GaAs:Cr, CdTe:V, and CdTe:V:Mn. If the two interfering optical fields are plane waves with negligible linewidth, a DC short-circuit photocurrent results whose properties can be used to determine the sign of the pre-dominant species of photo-excited charge carriers, their mobility-lifetime products, and some information about donor and trap concentrations if the mobilities are known. All experiments were performed with laser diode pumped Nd:YAG unidirectional ring oscillator lasers whose optical
Space charge compensation on the low energy beam transport of Linac4
AUTHOR|(SzGeCERN)733270; Scrivens, Richard; Jesus Castillo, Santos
Part of the upgrade program in the injector chains of the CERN accelerator complex is the replacement of the the proton accelerator Linac2 for the brand new Linac4 which will accelerate H$^-$ and its main goal is to increase the beam intensity in the next sections of the LHC accelerator chain. The Linac4 is now under commissioning and will use several ion sources to produce high intensity unbunched H$^-$ beams with different properties, and the low energy beam transport (LEBT) is the system in charge of match all these different beams to the Radio frequency quadrupole (RFQ). The space charge forces that spread the beam ions apart of each other and cause emittance growth limits the maximum intensity that can be transported in the LEBT, but the space charge of intense unbunched ion beams can be compensated by the generated ions by the impact ionization of the residual gas, which creates a source of secondary particles inside the beam pipe. For negative ion beams, the effect of the beam electric field is to ex...
Energy Technology Data Exchange (ETDEWEB)
Edward A. Startsev; Ronald C. Davidson
2004-04-09
To achieve high focal spot intensities in heavy ion fusion, the ion beam must be compressed longitudinally by factors of ten to one hundred before it is focused onto the target. The longitudinal compression is achieved by imposing an initial velocity profile tilt on the drifting beam. In this paper, the problem of longitudinal drift compression of intense charged particle beams is solved analytically for the two important cases corresponding to a cold beam, and a pressure-dominated beam, using a one-dimensional warm-fluid model describing the longitudinal beam dynamics.
Allis, D G; Spencer, J T
2001-07-02
A theoretical study of several new classes of polyhedral-based molecules has shown that these species display large calculated nonlinear optical responses. These new classes of molecules are based on charged aromatic subunits connected through polyhedral cluster bridges, such as closo-[1-(C(7)H(6))-12-(C(5)Me(4))C(2)B(10)H(10)]. These compounds show calculated first hyperpolarizabilities (beta) ranging from 6.5 to 8413.9 x 10(-30) cm(5) esu(-1). A basis for understanding the origin of these large responses is proposed based on the two-state model and consideration of the orbital and electronic features of the molecules. In general, the highest occupied molecular orbitals for these species are localized on the aromatic donor rings, such as the cyclopentadienyl system, while the lowest unoccupied molecular orbitals are largely on the aromatic acceptor rings, such as the tropylium system. The electronic properties of these polyhedral-based systems appear to be significantly different from the analogous organic [5.6.7]quinarene system (tropyliumcyclopentadienylbenzene). The organic quinarene appears to behave as a completely electron-delocalized system over all three rings while the polyhedral-based compounds can best be described as consisting of two relatively independent, highly polarized regions.
Directory of Open Access Journals (Sweden)
Yin Hua
2015-04-01
Full Text Available Estimation of state of charge (SOC is of great importance for lithium-ion (Li-ion batteries used in electric vehicles. This paper presents a state of charge estimation method using nonlinear predictive filter (NPF and evaluates the proposed method on the lithium-ion batteries with different chemistries. Contrary to most conventional filters which usually assume a zero mean white Gaussian process noise, the advantage of NPF is that the process noise in NPF is treated as an unknown model error and determined as a part of the solution without any prior assumption, and it can take any statistical distribution form, which improves the estimation accuracy. In consideration of the model accuracy and computational complexity, a first-order equivalent circuit model is applied to characterize the battery behavior. The experimental test is conducted on the LiCoO2 and LiFePO4 battery cells to validate the proposed method. The results show that the NPF method is able to accurately estimate the battery SOC and has good robust performance to the different initial states for both cells. Furthermore, the comparison study between NPF and well-established extended Kalman filter for battery SOC estimation indicates that the proposed NPF method has better estimation accuracy and converges faster.
Time-space symmetry as a solution to the mass hierarchy of charged lepton generations
Van Thuan, Vo
2015-01-01
Based on an extended time-space symmetry, a cylindrical model of gravitational geometrical dynamics with two time-like extra-dimensions leads to a microscopic geodesic description of the curved space-time. Due to interaction of a Higgs-like cosmological potential with individual space-time fluctuations, the original time-space symmetry is spontaneously broken, inducing a strong time-like curvature and a weak space-like deviation curve. As a result, the basic Klein-Gordon-Fock equation of a free massive elementary particle was derived, which implies a duality between the quantum mechanics equation and a microscopic geodesic description in the frame of general relativity. Consequently, Heisenberg inequalities are determined explicitly by the space-time curvatures. Moreover, extending curvatures to higher time-like dimensional hyper-spherical surfaces than one of the basic common cylindrical configuration, we found reasonable mass ratios of all charged leptons and succeeded to fix the number of their generations...
Nonlinear waves in electron–positron–ion plasmas including charge separation
Indian Academy of Sciences (India)
A MUGEMANA; S MOOLLA; I J LAZARUS
2017-02-01
Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth andspiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations.
Directory of Open Access Journals (Sweden)
H. K. Avetissian
2010-10-01
Full Text Available The nonlinear threshold phenomena of particle reflection and capture of electrons in the induced Compton process that have previously been revealed in the case of plane monochromatic counterpropagating waves, take place also with the actual nonplane laser pulses of ultrashort duration and lead to particle acceleration. In contrast to analogous phenomena in the induced Cherenkov and undulator processes, the Compton reflection-capture mechanism with laser pulses of relativistic intensities practically may be realized for arbitrary initial energies of particles. The acceleration effect for particles initially in rest is explored numerically, taking into account the significance of this case connected with the relativistic electron bunches of high densities, which currently may be realized by relativistic lasers on the ultrathin solid foils where the electrons initially are almost in rest.