Radiation effects on relativistic electrons in strong external fields
International Nuclear Information System (INIS)
Iqbal, Khalid
2013-01-01
The effects of radiation of high energy electron beams are a major issue in almost all types of charged particle accelerators. The objective of this thesis is both the analytical and numerical study of radiation effects. Due to its many applications the study of the self force has become a very active and productive field of research. The main part of this thesis is devoted to the study of radiation effects in laser-based plasma accelerators. Analytical models predict the existence of radiation effects. The investigation of radiation reaction show that in laser-based plasma accelerators, the self force effects lower the energy gain and emittance for moderate energies electron beams and increase the relative energy spread. However, for relatively high energy electron beams, the self radiation and retardation (radiation effects of one electron on the other electron of the system) effects increase the transverse emittance of the beam. The energy gain decreases to even lower value and relative energy spread increases to even higher value due to high radiation losses. The second part of this thesis investigates with radiation reaction in focused laser beams. Radiation effects are very weak even for high energy electrons. The radiation-free acceleration and the simple practical setup make direct acceleration in a focused laser beam very attractive. The results presented in this thesis can be helpful for the optimization of future electron acceleration experiments, in particular in the case of laser-plasma accelerators.
Relativistic quantum dynamics in strong fields: Photon emission from heavy, few-electron ions
International Nuclear Information System (INIS)
Fritzsche, S.; Stoehlker, T.
2005-03-01
Recent progress in the study of the photon emission from highly-charged heavy ions is reviewed. These investigations show that high-Z ions provide a unique tool for improving the understanding of the electron-electron and electron-photon interaction in the presence of strong fields. Apart from the bound-state transitions, which are accurately described in the framework of quantum electrodynamics, much information has been obtained also from the radiative capture of (quasi-) free electrons by high-Z ions. Many features in the observed spectra hereby confirm the inherently relativistic behavior of even the simplest compound quantum systems in nature. (orig.)
High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator
Sudar, N.; Musumeci, P.; Duris, J.; Gadjev, I.; Polyanskiy, M.; Pogorelsky, I.; Fedurin, M.; Swinson, C.; Kusche, K.; Babzien, M.; Gover, A.
2016-10-01
We present results of an experiment where, using a 200 GW CO2 laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.
International Nuclear Information System (INIS)
Wharton, C.B.
1977-01-01
A multi-kilovolt, moderate density plasma was generated in a magnetic mirror confinement system by two methods: turbulent heating and relativistic electron beam. Extensive diagnostic development permitted the measurement of important plasma characteristics, leading to interesting and novel conclusions regarding heating and loss mechanisms. Electron and ion heating mechanisms were categorized, and parameter studies made to establish ranges of importance. Nonthermal ion and electron energy distributions were measured. Beam propagation and energy deposition studies yielded the spatial dependence of plasma heating
Experimental study of transport of relativistic electron beams in strong magnetic mirror field
Sakata, Shohei; Kondo, Kotaro; Bailly-Grandvaux, Mathiu; Bellei, Claudio; Santos, Joao; Firex Project Team
2015-11-01
Relativistic electron beams REB produced by ultra high intense laser pulses have generally a large divergence angle that results in degradation of energy coupling between the REB and a fuel core in the fast ignition scheme. Guiding and focusing of the REB by a strong external magnetic field was proposed to achieve high efficiency. We investigated REB transport through 50 μm or 250 μm thick plastic foils CuI doped under external magnetic fields, in magnetic mirror configurations of 1.2 or 4 mirror ratio. The experiment was carried out at the GEKKO XII and LFEX laser facility. Spatial pattern of the REB was measured by coherent transition radiation and/or Cu Ka x ray emission from the rear surface of the foil targets. Strong collimation of the REB by the external magnetic field was observed with 50 μm thick plastic targets, while the REB scattered in 250 μm thick targets. The experimental results are compared with computer simulations to understand the physical mechanisms of the REB transport in the external magnetic field. This work is supported by NIFS (Japan), MEXT/JSPS KAKENHI (Japan), JSPS Fellowship (Japan), ANR (France) and COST (Europe).
Relativistically strong electromagnetic radiation in a plasma
Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Kiriyama, H.; Kondo, K.
2016-03-01
Physical processes in a plasma under the action of relativistically strong electromagnetic waves generated by high-power lasers have been briefly reviewed. These processes are of interest in view of the development of new methods for acceleration of charged particles, creation of sources of bright hard electromagnetic radiation, and investigation of macroscopic quantum-electrodynamical processes. Attention is focused on nonlinear waves in a laser plasma for the creation of compact electron accelerators. The acceleration of plasma bunches by the radiation pressure of light is the most efficient regime of ion acceleration. Coherent hard electromagnetic radiation in the relativistic plasma is generated in the form of higher harmonics and/or electromagnetic pulses, which are compressed and intensified after reflection from relativistic mirrors created by nonlinear waves. In the limit of extremely strong electromagnetic waves, radiation friction, which accompanies the conversion of radiation from the optical range to the gamma range, fundamentally changes the behavior of the plasma. This process is accompanied by the production of electron-positron pairs, which is described within quantum electrodynamics theory.
Strong-coupling diffusion in relativistic systems
Indian Academy of Sciences (India)
hanced values needed to interpret the data at higher energies point towards the importance of strong-coupling effects. ... when all secondary particles have been created. For short times in the initial phase ... It is decisive for a proper representation of the available data for relativistic heavy-ion collisions at and beyond SPS.
VEBA relativistic electron accelerator
International Nuclear Information System (INIS)
Parker, R.K.; Ury, M.
1975-01-01
The VEBA high-current, relativistic electron accelerator was designed and constructed at NRL for applications in the study of high-power microwave sources. To meet the requirements of this study, the accelerator was designed for operation in either a short (60 nsec) or long (2.2 μsec) pulse mode. The short-pulse mode has been in operation for nearly two years and has proven to be an extremely reliable design. The design of the long-pulse mode is now complete and component fabrication will soon be underway. The pulse-forming network in the short-pulse mode is an unbalanced, water Blumlein with an output impedance of 9.2 Ω. The Blumlein is pulse charged by a 17 stage Marx generator which has a series capacitance of 29.4 nF. By transmission along a tapered coaxial line, the output pulse is transformed to 20 Ω, and the voltage developed across a matched load increases to a maximum of 2.3 MV. The proposed conversion to the long-pulse mode will require the Blumlein and transformer sections be removed and the diode assembly be attached directly to the oversized Marx tank. The direct coupling between the Marx and the Blumlein will then be replaced by two nested water capacitors, which are shunted by spiral inductors. When coupled in series with the Marx, this output filter will form a three-section, voltage-fed, Guillemin (type A), pulse-forming network with a characteristic impedance of 40 Ω and a maximum output voltage of 0.9 MV. (auth)
Strong-field relativistic processes in highly charged ions
Energy Technology Data Exchange (ETDEWEB)
Postavaru, Octavian
2010-12-08
In this thesis we investigate strong-field relativistic processes in highly charged ions. In the first part, we study resonance fluorescence of laser-driven highly charged ions in the relativistic regime by solving the time-dependent master equation in a multi-level model. Our ab initio approach based on the Dirac equation allows for investigating highly relativistic ions, and, consequently, provides a sensitive means to test correlated relativistic dynamics, bound-state quantum electrodynamic phenomena and nuclear effects by applying coherent light with x-ray frequencies. Atomic dipole or multipole moments may be determined to unprecedented accuracy by measuring the interference-narrowed fluorescence spectrum. Furthermore, we investigate the level structure of heavy hydrogenlike ions in laser beams. Interaction with the light field leads to dynamic shifts of the electronic energy levels, which is relevant for spectroscopic experiments. We apply a fully relativistic description of the electronic states by means of the Dirac equation. Our formalism goes beyond the dipole approximation and takes into account non-dipole effects of retardation and interaction with the magnetic field components of the laser beam. We predicted cross sections for the inter-shell trielectronic recombination (TR) and quadruelectronic recombination processes which have been experimentally confirmed in electron beam ion trap measurements, mainly for C-like ions, of Ar, Fe and Kr. For Kr{sup 30}+, inter-shell TR contributions of nearly 6% to the total resonant photorecombination rate were found. (orig.)
Relativistic electron beams above thunderclouds
DEFF Research Database (Denmark)
Füellekrug, M.; Roussel-Dupre, R.; Symbalisty, E. M. D.
2011-01-01
of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of similar to 7MeV to transport a total charge of similar to-10mC upwards. The impulsive current similar to 3 x 10(-3) Am-2 associated with relativistic electron beams above thunderclouds...
Double Relativistic Electron Accelerating Mirror
Directory of Open Access Journals (Sweden)
Saltanat Sadykova
2013-02-01
Full Text Available In the present paper, the possibility of generation of thin dense relativistic electron layers is shown using the analytical and numerical modeling of laser pulse interaction with ultra-thin layers. It was shown that the maximum electron energy can be gained by optimal tuning between the target width, intensity and laser pulse duration. The optimal parameters were obtained from a self-consistent system of Maxwell equations and the equation of motion of electron layer. For thin relativistic electron layers, the gaining of maximum electron energies requires a second additional overdense plasma layer, thus cutting the laser radiation off the plasma screen at the instant of gaining the maximum energy (DREAM-schema.
Pivotal issues on relativistic electrons in ITER
Boozer, Allen H.
2018-03-01
The transfer of the plasma current from thermal to relativistic electrons is a threat to ITER achieving its mission. This danger is significantly greater in the nuclear than in the non-nuclear phase of ITER operations. Two issues are pivotal. The first is the extent and duration of magnetic surface breaking in conjunction with the thermal quenches. The second is the exponential sensitivity of the current transfer to three quantities: (1) the poloidal flux change required to e-fold the number of relativistic electrons, (2) the time τa after the beginning of the thermal quench before the accelerating electric field exceeds the Connor-Hastie field for runaway, and (3) the duration of the period τ_op in which magnetic surfaces remain open. Adequate knowledge does not exist to devise a reliable strategy for the protection of ITER. Uncertainties are sufficiently large that a transfer of neither a negligible nor the full plasma current to relativistic electrons can be ruled out during the non-nuclear phase of ITER. Tritium decay can provide a sufficiently strong seed for a dangerous relativistic-electron current even if τa and τ_op are sufficiently long to avoid relativistic electrons during non-nuclear operations. The breakup of magnetic surfaces that is associated with thermal quenches occurs on a time scale associated with fast magnetic reconnection, which means reconnection at an Alfvénic rather than a resistive rate. Alfvénic reconnection is well beyond the capabilities of existing computational tools for tokamaks, but its effects can be studied using its property of conserving magnetic helicity. Although the dangers to ITER from relativistic electrons have been known for twenty years, the critical issues have not been defined with sufficient precision to formulate an effective research program. Studies are particularly needed on plasma behavior in existing tokamaks during thermal quenches, behavior which could be clarified using methods developed here.
Relativistic generalization of strong plasma turbulence
International Nuclear Information System (INIS)
Chian, A.C.-L.
1982-01-01
Two fundamental electrostatic modes of an unmagnetized plasma, namely, ion acoustic mode and Langumir mode are studied. Previous theories are generalized to include the effect of relativistic mass variations. The existence of relativistic ion acoustic solitons is demonstrated. In addition, it is shown that simple, relativistic Langumir solitons do not exist in a infinite plasma. (L.C.) [pt
The relativistic electron wave equation
International Nuclear Information System (INIS)
Dirac, P.A.M.
1977-08-01
The paper was presented at the European Conference on Particle Physics held in Budapest between the 4th and 9th July of 1977. A short review is given on the birth of the relativistic electron wave equation. After Schroedinger has shown the equivalence of his wave mechanics and the matrix mechanics of Heisenberg, a general transformation theory was developed by the author. This theory required a relativistic wave equation linear in delta/delta t. As the Klein--Gordon equation available at this time did not satisfy this condition the development of a new equation became necessary. The equation which was found gave the value of the electron spin and magnetic moment automatically. (D.P.)
Electromagnetic responses of relativistic electrons
de Carvalho, C. A. A.; Reis, D. M.
2018-02-01
We compute the real and imaginary parts of the electric permittivities and magnetic permeabilities of relativistic electrons from quantum electrodynamics at finite temperatures and densities, for weak fields, neglecting electron-electron interactions. For non-zero temperatures, electromagnetic responses are reduced to one-dimensional integrals computed numerically. For zero temperature, we find analytic expressions for both their real/dispersive and imaginary/absorptive parts. As an application of our results, we obtain the dispersion relation for longitudinal electric plasmons. Present calculations support our recent claim that, at low frequencies and long wavelengths, the system will exhibit simultaneously negative electric and magnetic responses.
Relativistic electron beam device
Freeman, J.R.; Poukey, J.W.; Shope, S.L.; Yonas, G.
1975-07-01
A design is given for an electron beam device for irradiating spherical hydrogen isotope bearing targets. The accelerator, which includes hollow cathodes facing each other, injects an anode plasma between the cathodes and produces an approximately 10 nanosecond, megajoule pulse between the anode plasma and the cathodes. Targets may be repetitively positioned within the plasma between the cathodes, and accelerator diode arrangement permits materials to survive operation in a fusion power source. (auth)
Relativistic fluid formulation and theory of intense relativistic electron beams
International Nuclear Information System (INIS)
Siambis, J.G.
1984-01-01
A new general relativistic fluid formulation has been obtained for intense relativistic electron beams (IREB) with arbitrarily high relativistic mass factor γ. This theory is valid for confined IREB equilibria such as those found inside high energy accelerators as well as in the pinched and ion-focused regimes of beam propagation in plasma channels. The new relativistic fluid formulation is based on the covariant relativistic fluid formulation of Newcomb with the parameter lambda identical to 1, in order to allow for realistic confined equilibria. The resulting equilibrium constraints require that the beam has a slow rotational velocity around its direction of propagation and that the off-diagonal thermal stress element, associated with these two directions of motion, be nonzero. The effective betatron oscillation frequency of the fluid elements of the beam is modified by the radial gradient and anisotropies in the thermal stress elements of the beam fluid. The wave equation, for sausage, hose and filamentation excitations on the relativistic fluid beam, is found to be formally identical to that obtained from the Vlasov equation approach, hence phase-mixing damping is a generic and self-consistent correlate of the new relativistic fluid formulation
Relativistic rapprochement of electromagnetic and strong interactions
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1995-01-01
On the basis of the Lienard-Wiechert potential and the relativistic Yukawa potential it is shown that the corresponding interactions with velocity growth increase differently (the electromagnetic one increases faster). According to preliminary estimations they are equivalent, at distances of the 'action radius' of nuclear forces, at γ≅ 960, where γ is the Lorentz factor. 2 refs
Strong-coupling diffusion in relativistic systems
Indian Academy of Sciences (India)
FPE) in rapidity space analytically for the case of a time-dependent diffusion coefficient. The solutions represent SPS data for 158 A•GeV/c Pb+Pb very well. With the dependence of the rapidity relaxation coeffi- cients on the available relativistic ...
International Nuclear Information System (INIS)
Lefevre, Thibaut
2000-01-01
The next generation of electron-positron linear colliders must reach the TeV energy range. For this, one requires an adequate RF power source to feed the accelerating cavities of the collider. One way to generate this source is to use the Two Beam Accelerator concept in which the RF power is produced in resonant cavities driven by an intense bunched beam. In this thesis, I present the experimental results obtained at the CEA/CESTA using an electron beam generated by an induction linac. First, some studies were performed with the LELIA induction linac (2.2 MeV, 1 kA, 80 ns) using a Free Electron Laser (FEL) as a buncher at 35 GHz. A second part relates the experiment made with the PIVAIR induction linac (7 MeV, 1 kA, 80 ns) in order to measure the RF power extracted from a resonant cavity at 35 GHz, which is driven by the bunches produced in the FEL. One can also find a simple theoretical modeling of the beam-cavity interaction, and the numerical results dealing with the design of the cavity we tested. (author) [fr
Dechanneling function for relativistic axially channeled electrons
International Nuclear Information System (INIS)
Muralev, V.A.; Telegin, V.I.
1981-01-01
Behaviour of the x(t) dechanneling function depending on the depth is theoretically studied. Theoretical consideration of x(t) for axial channeled relativistic electrons in anisotropic medium results in two-dimensional kinetic equation with mixed derivatives of the parabolic type. The kinetic equation in the approximation of the continuous Lindchard model for relativistic axial channeled electrons is numerically solved. The depth dependence of the x(t) dechanneling function is obtained [ru
Energy Dependence of Near-relativistic Electron Spectrum at ...
Indian Academy of Sciences (India)
the Relativistic Electron Dropouts (REDs) and the Relativistic Electron Enhancements. (REEs) observed at the geosynchronous altitudes. The sudden drop in the relativistic electron flux often by two orders of magnitude is called RED which is usually pre- ceded by the gradual enhancement in the relativistic electron fluxes, ...
Strong-coupling diffusion in relativistic systems
Indian Academy of Sciences (India)
Different from the early universe, heavy-ion collisions at very high energies do not reach statistical equilibrium, although thermal models explain many of their features. To account for nonequilibrium strong-coupling effects, a Fokker–Planck equation with time-dependent diffusion coefﬁcient is proposed. A schematic model ...
Magnetized relativistic electron-ion plasma expansion
Benkhelifa, El-Amine; Djebli, Mourad
2016-03-01
The dynamics of relativistic laser-produced plasma expansion across a transverse magnetic field is investigated. Based on a one dimensional two-fluid model that includes pressure, enthalpy, and rest mass energy, the expansion is studied in the limit of λD (Debye length) ≤RL (Larmor radius) for magnetized electrons and ions. Numerical investigation conducted for a quasi-neutral plasma showed that the σ parameter describing the initial plasma magnetization, and the plasma β parameter, which is the ratio of kinetic to magnetic pressure are the key parameters governing the expansion dynamics. For σ ≪ 1, ion's front shows oscillations associated to the break-down of quasi-neutrality. This is due to the strong constraining effect and confinement of the magnetic field, which acts as a retarding medium slowing the plasma expansion.
Resonant enhancement of relativistic electron fluxes during geomagnetically active periods
Directory of Open Access Journals (Sweden)
I. Roth
Full Text Available The strong increase in the flux of relativistic electrons during the recovery phase of magnetic storms and during other active periods is investigated with the help of Hamiltonian formalism and simulations of test electrons which interact with whistler waves. The intensity of the whistler waves is enhanced significantly due to injection of 10-100 keV electrons during the substorm. Electrons which drift in the gradient and curvature of the magnetic field generate the rising tones of VLF whistler chorus. The seed population of relativistic electrons which bounce along the inhomogeneous magnetic field, interacts resonantly with the whistler waves. Whistler wave propagating obliquely to the magnetic field can interact with energetic electrons through Landau, cyclotron, and higher harmonic resonant interactions when the Doppler-shifted wave frequency equals any (positive or negative integer multiple of the local relativistic gyrofrequency. Because the gyroradius of a relativistic electron may be the order of or greater than the perpendicular wavelength, numerous cyclotron, harmonics can contribute to the resonant interaction which breaks down the adiabatic invariant. A similar process diffuses the pitch angle leading to electron precipitation. The irreversible changes in the adiabatic invariant depend on the relative phase between the wave and the electron, and successive resonant interactions result in electrons undergoing a random walk in energy and pitch angle. This resonant process may contribute to the 10-100 fold increase of the relativistic electron flux in the outer radiation belt, and constitute an interesting relation between substorm-generated waves and enhancements in fluxes of relativistic electrons during geomagnetic storms and other active periods.
Key words. Magnetospheric physics (energetic particles · trapped; plasma waves and instabilities; storms and substorms
Intense relativistic electron beam: generation and propagation
International Nuclear Information System (INIS)
Mittal, K.C.; Mondal, J.
2010-01-01
A general review of relativistic electron beam extracted from explosive field emission diode has been presented here. The beam current in the diode gap taking into account cathode and anode plasma expansion velocity and excluding the self magnetic field effect is directly proportional to gap voltage V 3/2 and inversely proportional to the square of the effective diode gap (d-vt). In the limit of high current, self magnetic field focusing effect comes into play and results in a critical current at which pinching will take place. When the diode current exceeds the critical current, the electron flow is in the para-potential regime. Different diode geometries such as planner, coaxial, rod-pinched, reflex triode are discussed qualitatively. When the beam is injected into a vacuum drift tube the propagation of the beam is only possible in presence of a strong axial magnetic field which prevents the beam expansion in the radial direction. If the beam is injected in the drift tube filled with dense plasma, then the redistribution of the plasma electrons effectively neutralizes the beam space charge, resulting subsequent propagation of the beam along the drift tube. The beam propagation through neutral gas is similar to the plasma filled drift tube. In this case both the neutral gas pressure and the beam current regulate the transmission of the REB. (author)
Relativistic Electrons in Electric Discharges
DEFF Research Database (Denmark)
Cinar, Deniz
Thunderstorms generate bursts of X- and Gamma radiation. When observed from spacecraft, the bursts are referred to as “Terrestrial Gamma-ray Flashes” (TGFs). They are bremsstrahlung from energetic electrons accelerated in thunderstorm electric _elds. The TGFs were _rst observed in the 90ties...... at the time when also gigantic electric discharges were observed at 10-90 km altitude in the stratosphere and mesosphere, the so called “jets” and “sprites”, commonly referred to as “Transient Luminous Events” (TLEs). TGFs were _rst thought connected to TLEs, but later research has pointed to lightning...... have studied the electron acceleration and photon generation in a constant electric _eld under a variety of conditions. These include the energy and number of seed electrons, electric_eld and altitude. We found that the distributions of avalanche electrons and photons are insensitive...
Enhanced transport of relativistic electrons through nanochannels
Directory of Open Access Journals (Sweden)
Prashant Kumar Singh
2013-06-01
Full Text Available Efficient transport of fast electrons driven by intense laser solid interaction depends crucially on optimal target design. We demonstrate a hybrid target design that incorporates two important features—efficient generation of relativistic electrons and their unimpeded transport in dense media. The target was fabricated on a porous alumina base consisting of an array of sublambda cylindrical holes partially filled with Cu nanorods, such that light field propagates in the hollow channels, located ahead of the metallic fillings. The hollow array acts as an efficient source of hot electrons when driven by relativistically intense, femtosecond laser pulses and shows a 60-fold enhancement in electron flux compared to a solid target. This enhancement is ascribed to an increased penetration of laser through subwavelength pores and enhanced local electric fields. The metal doped part facilitates efficient transport of the generated electrons, due to its large background conductivity. A 4-fold enhancement in target rear side electron flux is observed compared with unfilled porous alumina.
Structure and thermodynamic properties of relativistic electron gases.
Liu, Yu; Wu, Jianzhong
2014-07-01
Relativistic effect is important in many quantum systems but theoretically complicated from both fundamental and practical perspectives. Herein we introduce an efficient computational procedure to predict the structure and energetic properties of relativistic quantum systems by mapping the Pauli principle into an effective pairwise-additive potential such that the properties of relativistic nonquantum systems can be readily predicted from conventional liquid-state methods. We applied our theoretical procedure to relativistic uniform electron gases and compared the pair correlation functions with those for systems of nonrelativistic electrons. A simple analytical expression has been developed to correlate the exchange-correlation free energy of relativistic uniform electron systems.
Certain relativistic effects due to strong electromagnetic fields in plasmas
International Nuclear Information System (INIS)
Tsintsadze, N.L.
1974-01-01
It is shown that the propagation of a strong electromagnetic wave in an electron plasma can lead to a generation of a constant electron current along the direction of propagation and to a large increase in the average electron density. (Auth.)
Borovsky, Joseph E.
2017-12-01
Time-integral correlations are examined between the geosynchronous relativistic electron flux index Fe1.2 and 31 variables of the solar wind and magnetosphere. An "evolutionary algorithm" is used to maximize correlations. Time integrations (into the past) of the variables are found to be superior to time-lagged variables for maximizing correlations with the radiation belt. Physical arguments are given as to why. Dominant correlations are found for the substorm-injected electron flux at geosynchronous orbit and for the pressure of the ion plasma sheet. Different sets of variables are constructed and correlated with Fe1.2: some sets maximize the correlations, and some sets are based on purely solar wind variables. Examining known physical mechanisms that act on the radiation belt, sets of correlations are constructed (1) using magnetospheric variables that control those physical mechanisms and (2) using the solar wind variables that control those magnetospheric variables. Fe1.2-increasing intervals are correlated separately from Fe1.2-decreasing intervals, and the introduction of autoregression into the time-integral correlations is explored. A great impediment to discerning physical cause and effect from the correlations is the fact that all solar wind variables are intercorrelated and carry much of the same information about the time sequence of the solar wind that drives the time sequence of the magnetosphere.
Foil focusing of relativistic electron beams
Energy Technology Data Exchange (ETDEWEB)
Ekdahl, Jr., Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-10-26
When an intense relativistic electron beams (IREB) passes through a grounded metal foil, the transverse electric field due to the beam space charge is locally shorted out, and the beam is focused by the magnetic field of its current. The effect can be treated as focusing by a thin lens with first order aberration. Expressions for the focal length and aberration coefficient of the equivalent thin lens are developed in this note. These are then applied to practical examples representative of IREB research at Los Alamos National Laboratory.
Plasma heating by a relativistic electron beam
International Nuclear Information System (INIS)
Janssen, G.C.A.M.
1983-01-01
This thesis is devoted to the interaction of a Relativistic Electron Beam (REB) with a plasma. The goal of the experiment described herein is to study in detail the mechanism of energy transfer from the beam to the plasma. The beam particles have an energy of 800 keV, a current of 6 kA, a diameter of 3 cm and an adjustable pulse length of 50-150 ns. This beam is injected into cold hydrogen and helium plasmas with densities ranging from 10 18 to 10 20 m -3 . First, the technical aspects of the experiment are described. Then measurements on the hf fields excited by the REB-plasma are presented (optical line profiles and spectra of beam electrons). The final section is devoted to plasma heating. (Auth.)
The Work Function Associated with Ultra-relativistic Electron ...
Indian Academy of Sciences (India)
Following an extremely interesting idea (Schieber 1984), published long ago, the work function associated with the emission of ultra-relativistic electrons from magnetically deformed metallic crystal (mainly iron) at the outer crust of a magnetar is obtained using relativistic version of Thomas–Fermi type model for electron ...
Lyubarsky, Yuri
2018-02-01
This paper is the first in the series of papers aiming to study interaction of the electromagnetic precursor waves generated at the front of a relativistic shock with the upstream flow. It is motivated by a simple consideration showing that the absorption of such an electromagnetic precursor could yield an efficient transformation of the kinetic energy of the upstream flow to the energy of accelerated particles. Taking into account that the precursor is a strong wave, in which electrons oscillate with relativistic velocities, the standard plasma-radiation interaction processes should be reconsidered. In this paper, I calculate the synchrotron absorption of strong electromagnetic waves.
Effects of strong radiation reaction and quantum-electrodynamics on relativistic transparency
Zhang, Peng; Thomas, A. G. R.; Ridgers, C. P.
2013-10-01
Relativistic transparency is the process that optically switches the overdense plasma from opaque to transparent and enables light propagation through the otherwise opaque plasma, when light of sufficient intensity drives the electrons in the plasma to near light speeds. We study the relativistic transparency in radiation dominant and strong quantum electrodynamic (QED) regime, for the interaction of high-intensity laser pulses with a thin foil solid target. We analytically study the simplified motion of an electron in a circularly polarized plane wave to understand the physics of the transmissivity and absorption in the presence of classical and quantum-corrected, semiclassical radiation-reaction forces and the trapping of particles in nodes of laser standing wave through radiative cooling. These arguments are supported by both one dimensional and two dimensional particle-in-cell calculations including strong field QED effects. Measurement of the transmission of these pulses would be experimentally feasible and a robust test of the strong field QED particle-in-cell framework.
Relativistic nonlinear electrodynamics the QED vacuum and matter in super-strong radiation fields
Avetissian, Hamlet K
2016-01-01
This revised edition of the author’s classic 2006 text offers a comprehensively updated review of the field of relativistic nonlinear electrodynamics. It explores the interaction of strong and super-strong electromagnetic/laser radiation with the electromagnetic quantum vacuum and diverse types of matter – including free charged particles and antiparticles, acceleration beams, plasma and plasmous media. The appearance of laser sources of relativistic and ultra-relativistic intensities over the last decade has stimulated investigation of a large class of processes under such super-strong radiation fields. Revisions for this second edition reflect these developments and the book includes new chapters on Bremsstrahlung and nonlinear absorption of superintense radiation in plasmas, the nonlinear interaction of relativistic atoms with intense laser radiation, nonlinear interaction of strong laser radiation with Graphene, and relativistic nonlinear phenomena in solid-plasma targets under supershort laser pul...
Quantum resonances in reflection of relativistic electrons and positrons
International Nuclear Information System (INIS)
Eykhorn, Yu.L.; Korotchenko, K.B.; Pivovarov, Yu.L.; Takabayashi, Y.
2015-01-01
Calculations based on the use of realistic potential of the system of crystallographic planes confirm earlier results on existence of resonances in reflection of relativistic electrons and positrons by the crystal surface, if the crystallographic planes are parallel to the surface.The physical reason of predicted phenomena, similar to the band structure of transverse energy levels, is connected with the Bloch form of the wave functions of electrons (positrons) near the crystallographic planes, which appears both in the case of planar channeling of relativistic electrons (positrons) and in reflection by a crystal surface. Calculations show that positions of maxima in reflection of relativistic electrons and positrons by crystal surface specifically depend on the angle of incidence with respect to the crystal surface and relativistic factor of electrons/positrons. These maxima form the Darwin tables similar to that in ultra-cold neutron diffraction
International Nuclear Information System (INIS)
Bodek, K.; Rozpędzik, D.; Zejma, J.; Caban, P.; Rembieliński, J.; Włodarczyk, M.; Ciborowski, J.; Enders, J.; Köhler, A.; Kozela, A.
2013-01-01
The Polish-German project QUEST aims at studying relativistic quantum spin correlations of the Einstein-Rosen-Podolsky-Bohm type, through measurement of the correlation function and the corresponding probabilities for relativistic electron pairs. The results will be compared to theoretical predictions obtained by us within the framework of relativistic quantum mechanics, based on assumptions regarding the form of the relativistic spin operator. Agreement or divergence will be interpreted in the context of non-uniqueness of the relativistic spin operator in quantum mechanics as well as dependence of the correlation function on the choice of observables representing the spin. Pairs of correlated electrons will originate from the Mo/ller scattering of polarized 15 MeV electrons provided by the superconducting Darmstadt electron linear accelerator S-DALINAC, TU Darmstadt, incident on a Be target. Spin projections will be determined using the Mott polarimetry technique. Measurements (starting 2013) are planned for longitudinal and transverse beam polarizations and different orientations of the beam polarization vector w.r.t. the Mo/ller scattering plane. This is the first project to study relativistic spin correlations for particles with mass
PREFACE: Strongly correlated electron systems Strongly correlated electron systems
Saxena, Siddharth S.; Littlewood, P. B.
2012-07-01
This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to go—note that this progress is founded on investments and studies in the fundamentals of condensed matter physics from more than 50 years ago. Nevertheless, the defining challenges for the 21st century will lie in the discovery in science, and deployment through engineering, of technologies that can deliver the scale needed to have an impact on the sustainability agenda. Thus the big developments in nanotechnology may lie not in the pursuit of yet smaller transistors, but in the design of new structures that can revolutionise the performance of solar cells, batteries, fuel cells, light-weight structural materials, refrigeration, water purification, etc. The science presented in the papers of this special section also highlights the underlying interest in energy-dense materials, which
Relativistic Electron Pitch Angle Distributions in the Inner Magnetosphere
Friedel, Reiner; Zhao, Hong; Reeves, Geoff; Chen, Yue; Henderson, Mike; Kanekal, Shri; Baker, Dan; Jaynes, Allison
2017-04-01
Relativistic electron pitch angle distributions (PADs) in the trapped inner region of the magnetosphere are a sensitive measure of many processes that govern the dynamics of these particles. We report here on statistical observations of relativistic electron PADs from the REPT (Relativistic Electron/Proton Telescope) instrument aboard the Van Allen Probes mission, which show an unexpected dawn/dusk asymmetry that seems to be a persistent feature during quiet times of Dst > -20 nT. The observed PADs show a more peaked pancake distribution at dusk compared to dawn for energies above 1.8 MeV only. Energies from a few 100 KeV to 1 m,eV do NOT show these asymmetries, ruling out magnetic field model effects. These observations hint at persistent processes that can act on relativistic electrons on timescales on the order of the outer radiation belt drift period (10 minutes).
Spin dynamics in relativistic ionization with highly charged ions in super-strong laser fields
International Nuclear Information System (INIS)
Klaiber, Michael; Yakaboylu, Enderalp; Bauke, Heiko; Hatsagortsyan, Karen Z; Müller, Carsten; Paulus, Gerhard G
2014-01-01
Spin dynamics and induced spin effects in above-threshold ionization of hydrogenlike highly charged ions in super-strong laser fields are investigated. Spin-resolved ionization rates in the tunnelling regime are calculated by employing two versions of a relativistic Coulomb-corrected strong-field approximation (SFA). An intuitive simpleman model is developed which explains the derived scaling laws for spin flip and spin asymmetry effects. The intuitive model as well as our ab initio numerical simulations support the analytical results for the spin effects obtained in the dressed SFA where the impact of the laser field on the electron spin evolution in the bound state is taken into account. In contrast, the standard SFA is shown to fail in reproducing spin effects in ionization even at a qualitative level. The anticipated spin-effects are expected to be measurable with modern laser techniques combined with an ion storage facility. (paper)
Energy Technology Data Exchange (ETDEWEB)
Takamoto, Makoto [Department of Earth and Planetary Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Lazarian, Alexandre, E-mail: mtakamoto@eps.s.u-tokyo.ac.jp, E-mail: alazarian@facstaff.wisc.edu [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States)
2016-11-10
In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using three-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfvén) following the procedure of mode decomposition in Cho and Lazarian, and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfvén mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfvén Mach number, but also with the background magnetization, which indicates a strong coupling between the fast and Alfvén modes. It also signifies the appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfvén modes are strongly coupled and, unlike the non-relativistic MHD regime, cannot be treated separately. This finding will affect particle acceleration efficiency obtained by assuming Alfvénic critical-balance turbulence and can change the resulting photon spectra emitted by non-thermal electrons.
Focusing of relativistic electron beams by a solid cone
International Nuclear Information System (INIS)
Chen, M; Sheng, Z M; Ma, Y Y; Li, Y T; Yuan, X H; Zhang, J
2008-01-01
A scheme for focusing relativistic electron beams has been proposed by use of a solid cone based upon two dimensional particle-in-cell simulations. We compare the transport of hot electrons, produced during the interaction of ultra-intense laser pulse with the targets, through the cone shape target and a flat target. It is found that relativistic electrons can be confined and focused effectively in the cone target case, where both the electron density and temperature have been increased more significantly than the flat target case
The Controlling Parameters for EMIC Wave Scattering of Relativistic Electrons
Zhang, X.; Li, W.; Ma, Q.; Thorne, R. M.; Angelopoulos, V.; Bortnik, J.
2016-12-01
Although there is growing support for relativistic electron losses due to precipitation from electromagnetic ion cyclotron (EMIC) wave scattering, this mechanism is yet to be quantified. Such a quantification has been difficult in the past, because equatorial electron measurements simultaneous with EMIC waves have been limited, due to the highly localized presence of EMIC waves in the magnetosphere. In this study, we examine parameters controlling characteristics of EMIC wave induced relativistic (0.3-6 MeV) electron scattering, directly based on simultaneous wave and particle measurements from Van Allen Probes. We first present a case study when relativistic electrons respond differently during two intervals of intense ( 1 nT) EMIC wave observations: one with no scattering signature and one with efficient electron losses at >1.8 MeV. Based on the observed EMIC wave spectra and background plasma conditions, we calculate the wave diffusion rates and model the evolution of electron pitch angle distributions. By comparing the modeled results with local observations of pitch angle distributions, we demonstrate that fpe/fce is critical in controlling the effectiveness of EMIC waves in scattering multi-MeV electrons. We then expand our analysis to explore the conditions (such as fpe/fce, wave frequency spectra, and ring current ion temperature and anisotropy levels) favorable for EMIC wave scattering multi-MeV electrons through multi-event analyses. Our study is important for accurately modeling relativistic electron loss processes in radiation belt electron forecasts.
Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering
Gamayunov, K. V.; Khazanov, G. V.
2006-01-01
The flux level of outer-zone relativistic electrons (above 1 MeV) is extremely variable during geomagnetic storms, and controlled by a competition between acceleration and loss. Precipitation of these electrons due to resonant pitch-angle scattering by electromagnetic ion cyclotron (EMIC) waves is considered one of the major loss mechanisms. This mechanism was suggested in early theoretical studies more than three decades ago. However, direct experimental evidence of the wave role in relativistic electrons precipitation is difficult to obtain because of lack of concurrent measurements of precipitating electrons at low altitudes and the waves in a magnetically conjugate equatorial region. Recently, the data from balloon-borne X-ray instruments provided indirect but strong evidence on an efficiency of the EMIC wave induced loss for the outer-zone relativistic electrons. These observations stimulated theoretical studies that, particularly, demonstrated that EMIC wave induced pitch-angle diffusion of MeV electrons can operate in the strong diffusion limit and this mechanism can compete with relativistic electron depletion caused by the Dst effect during the initial and main phases of storm. Although an effectiveness of relativistic electron scattering by EMIC waves depends strongly on the wave spectral properties, the most favorable assumptions regarding wave characteristics has been made in all previous theoretical studies. Particularly, only quasi field-aligned EMIC waves have been considered as a driver for relativistic electron loss. At the same time, there is growing experimental and theoretical evidence that these waves can be highly oblique; EMIC wave energy can occupy not only the region of generation, i.e. the region of small wave normal angles, but also the entire wave normal angle region, and even only the region near 90 degrees. The latter can dramatically change he effectiveness of relativistic electron scattering by EMIC waves. In the present study, we
Ionization, photoelectron dynamics and elastic scattering in relativistic, ultra-strong field
Luo, Sui
Ultrastrong laser-matter interaction has direct bearing to next generation technologies including plasma acceleration, laser fusion and attosecond X-ray generation. The commonly known physics in strong field becomes different as one progress to ultrastrong field. The works presented in this dissertation theoretically study the influence of relativistic effect and magnetic component of the laser field on the ionization, photoelectron dynamics and elastic scattering processes. The influence of magnetic component (B laser) of circularly polarized (CP) ultrastrong fields (up to3 x 1022 W/cm2) on atomic bound state dynamics is investigated. The Poincare plots are used to find the changes in trajectory energies are on the order of a few percent for intensities up to1 x 1022 W/cm2. It is found that at intensities where ionization approaches 50% for the bound state, the small changes from Blaser of the circular polarized light can actually result in a several-fold decrease in ionization probability. The force on the bound electron exerted by the Lorentz force from B laser is perpendicular to the rotating plane of the circular polarized light, and this nature makes those trajectories which are aligned away from the minimum in the potential barrier stabilized against tunneling ionization. Our results provide a classical understanding for ionization in ultrastrong fields and indicate that relativistic effects in ultrastrong field ionization may most easily be seen with CP fields. The photoelectron energy spectra from elastic rescattering in ultrastrong laser fields (up to 2x1019 W/cm2) is studied by using a relativistic adaption of a semi-classical three-step recollision model. The Hartree-Fock scattering potentials are used in calculating the elastic rescattering for both hydrogenlike and noble gas species. It is found that there is a reduction in elastic rescattering for intensities beyond 6 x 1016 W/cm2 when the laser Lorentz deflection of the photoelectron exceeds its
EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems
Ronning, Filip; Batista, Cristian
2011-03-01
Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010—co-chaired by John Sarrao and Joe Thompson—followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed
Persistent current of relativistic electrons on a Dirac ring in presence of impurities
Ghosh, Sumit
2014-08-01
We study the behaviour of persistent current of relativistic electrons on a one dimensional ring in presence of attractive/repulsive scattering potentials. In particular, we investigate the persistent current in accordance with the strength as well as the number of the scattering potential. We find that in presence of single scatterer the persistent current becomes smaller in magnitude than the scattering free scenario. This behaviour is similar to the non-relativistic case. Even for a very strong scattering potential, finite amount of persistent current remains for a relativistic ring. In presence of multiple scatterer we observe that the persistent current is maximum when the scatterers are placed uniformly compared to the current averaged over random configurations. However if we increase the number of scatterers, we find that the random averaged current increases with the number of scatterers. The latter behaviour is in contrast to the non-relativistic case. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
A comparative study between all-electron scalar relativistic ...
Indian Academy of Sciences (India)
Abstract. A comparative study between all-electron relativistic (AER) calculation and all-electron (AE) cal- culation on the H2 molecule adsorption onto small gold clusters has been performed. Compared with the corres- ponding AunH2 cluster obtained by AE method, the AunH2 cluster obtained by AER method has much ...
Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons.
Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q-G; Zhou, X-Z; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y-X; Gao, Zhonglei; He, Zhaoguo; Baker, D N; Spence, H E; Reeves, G D; Blake, J B; Wygant, J R
2015-12-22
Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.
Present status of the theoretical relativistic plasma SHF electronics
International Nuclear Information System (INIS)
Kuzelev, M.V.; Rukhadze, A.A.
2000-01-01
Paper presents a review of theoretical investigations into powerful sources of SHF waves grounded on the forced emission of relativistic electron beams in plasma wave guides and resonator. Emission sources operating under amplification of a certain inlet signal and under generation mode were studied. Two mechanisms of forced emission: resonance Cherenkov radiation of relativistic electron beams in plasma and nonresonance Pierce emission resulting from evolution of high-frequency Pierce instability, were studied. Paper discusses theoretical problems only, all evaluations and calculations are made for the parameters of the exact experiments, the theoretical results are compared with the available experimental data. Factors affecting formation of spectrum of waves excited by relativistic electron beam in plasma systems are discussed [ru
Correlation function and electronic spectral line broadening in relativistic plasmas
Directory of Open Access Journals (Sweden)
Douis S.
2013-01-01
Full Text Available The electrons dynamics and the time autocorrelation function Cee(t for the total electric microfield of the electrons on positive charge impurity embedded in a plasma are considered when the relativistic dynamic of the electrons is taken into account. We have, at first, built the effective potential governing the electrons dynamics. This potential obeys a nonlinear integral equation that we have solved numerically. Regarding the electron broadening of the line in plasma, we have found that when the plasma parameters change, the amplitude of the collision operator changes in the same way as the time integral of Cee(t. The electron-impurity interaction is taken at first time as screened Deutsh interaction and at the second time as Kelbg interaction. Comparisons of all interesting quantities are made with respect to the previous interactions as well as between classical and relativistic dynamics of electrons.
Relativistic Electrons Produced by Foreshock Disturbances Observed Upstream of Earth's Bow Shock
Wilson, L. B., III; Sibeck, D. G.; Turner, D. L.; Osmane, A.; Caprioli, D.; Angelopoulos, V.
2016-01-01
Charged particles can be reflected and accelerated by strong (i.e., high Mach number) astrophysical collisionless shock waves, streaming away to form a foreshock region in communication with the shock. Foreshocks are primarily populated by suprathermal ions that can generate foreshock disturbances-largescale (i.e., tens to thousands of thermal ion Larmor radii), transient (approximately 5-10 per day) structures. They have recently been found to accelerate ions to energies of several keV. Although electrons in Saturn's high Mach number (M > 40) bow shock can be accelerated to relativistic energies (nearly 1000 keV), it has hitherto been thought impossible to accelerate electrons beyond a few tens of keV at Earth's low Mach number (1 =M shock. Here we report observations of electrons energized by foreshock disturbances to energies up to at least approximately 300 keV. Although such energetic electrons have been previously observed, their presence has been attributed to escaping magnetospheric particles or solar events. These relativistic electrons are not associated with any solar or magnetospheric activity. Further, due to their relatively small Larmor radii (compared to magnetic gradient scale lengths) and large thermal speeds (compared to shock speeds), no known shock acceleration mechanism can energize thermal electrons up to relativistic energies. The discovery of relativistic electrons associated with foreshock structures commonly generated in astrophysical shocks could provide a new paradigm for electron injections and acceleration in collisionless plasmas.
Electronic structure of molecules using relativistic effective core potentials
International Nuclear Information System (INIS)
Hay, P.J.
1981-01-01
Starting with one-component Cowan-Griffin relativistic Hartree-Fock orbitals, which successfully incorporate the mass-velocity and Darwin terms present in more complicated wavefunctions such as Dirac-Hartree-Fock, one can derive relativistic effective core potentials (RECP's) to carry out molecular calculations. These potentials implicitly include the dominant relativistic terms for molecules while allowing one to use the traditional quantum chemical techniques for studying the electronic structure of molecules. The effects of spin-orbit coupling can then be included using orbitals from such calculations using an effective 1-electron, 1-center spin-orbit operator. Applications to molecular systems involving heavy atoms, show good agreement with available spectroscopic data on molecular geometries and excitation energies
National Aeronautics and Space Administration — A Compact Relativistic Electron Proton Telescope (CREPT) to Investigate Magnetospheric Electron Microbursts is a project to build a solid-state (SSD) particle...
Electromagnetic surface waves at the interface of a relativistic electron beam with vacuum
International Nuclear Information System (INIS)
Shoucri, M.M.; Gagne, R.R.J.
1977-01-01
The dispersion relation for electromagnetic surface waves propagating at the interface between a relativistic electron beam and vacuum is derived. The excitation of surface modes in a plasma at rest by a relativistic electron beam is discussed
A comparative study between all-electron scalar relativistic ...
Indian Academy of Sciences (India)
gold cluster and the reactivity enhancement of H2 molecule. It may be one of the reasons why the dissociative .... computational method and cluster model are described in section 2, calculation results and discussions are ... core electrons; instead they supplement the core poten- tials with approximate relativistic effects.
Energy Dependence of Near-relativistic Electron Spectrum at ...
Indian Academy of Sciences (India)
2016-01-27
Jan 27, 2016 ... This may give us some insight into how we can safeguard geostationary satellites from functional anomalies of the deep dielectric charging type, which are caused by charge accumulation and subsequent discharge of relativistic electrons. In this study we examine whether there is any energy dependence ...
Source and seed populations for relativistic electrons: Their roles in radiation belt changes
Jaynes, AN; Baker, DN; Singer, HJ; Rodriguez, JV; Loto'aniu, TM; Ali, AF; Elkington, SR; Li, X; Kanekal, SG; Fennell, JF; Li, W; Thorne, RM; Kletzing, CA; Spence, HE; Reeves, GD
2015-01-01
©2015. American Geophysical Union. All Rights Reserved. Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period in...
Source and seed populations for relativistic electrons: Their roles in radiation belt changes
Jaynes, AN; Baker, DN; Singer, HJ; Rodriguez, JV; Rodriguez, JV; Loto'aniu, TM; Loto'aniu, TM; Ali, AF; Elkington, SR; Li, X; Kanekal, SG; Fennell, JF; Li, W; Thorne, RM; Kletzing, CA
2015-01-01
© 2015. American Geophysical Union. All Rights Reserved. Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period i...
Relativistic electron dropout echoes induced by interplanetary shocks
Schiller, Q.; Kanekal, S. G.; Boyd, A. J.; Baker, D. N.; Blake, J. B.; Spence, H. E.
2017-12-01
Interplanetary shocks that impact Earth's magnetosphere can produce immediate and dramatic responses in the trapped relativistic electron population. One well-studied response is a prompt injection capable of transporting relativistic electrons deep into the magnetosphere and accelerating them to multi-MeV energies. The converse effect, electron dropout echoes, are observations of a sudden dropout of electron fluxes observed after the interplanetary shock arrival. Like the injection echo signatures, dropout echoes can also show clear energy dispersion signals. They are of particular interest because they have only recently been observed and their causal mechanism is not well understood. In the analysis presented here, we show observations of electron drift echo signatures from the Relativistic Electron-Proton Telescope (REPT) and Magnetic Electron and Ion Sensors (MagEIS) onboard NASA's Van Allen Probes mission, which show simultaneous prompt enhancements and dropouts within minutes of the associated with shock impact. We show that the observations associated with both enhancements and dropouts are explained by the inward motion caused by the electric field impulse induced by the interplanetary shock, and either energization to cause the enhancement, or lack of a seed population to cause the dropout.
Electron-deuteron scattering in a relativistic theory of hadrons
International Nuclear Information System (INIS)
Phillips, D.
1998-11-01
The author reviews a three-dimensional formalism that provides a systematic way to include relativistic effects including relativistic kinematics, the effects of negative-energy states, and the boosts of the two-body system in calculations of two-body bound-states. He then explains how to construct a conserved current within this relativistic three-dimensional approach. This general theoretical framework is specifically applied to electron-deuteron scattering both in impulse approximation and when the ρπγ meson-exchange current is included. The experimentally-measured quantities A, B, and T 20 are calculated over the kinematic range that is probed in Jefferson Lab experiments. The role of both negative-energy states and meson retardation appears to be small in the region of interest
Self-focusing relativistic electron streams in plasmas
International Nuclear Information System (INIS)
Cox, J.L. Jr.
1975-01-01
A relativistic electron stream propagating through a dense plasma induces current and charge densities which determine how the stream can self-focus. Magnetic self-focusing is possible because stream-current neutralization, although extensive, is not complete. Electric self-focusing can occur because the stream charge becomes overneutralized when the net current is smaller than a critical value. Under some circumstances, the latter process can cause the stream to focus into a series of electron bunches
Schlegel, Theodor; Tikhonchuk, Vladimir T.
2012-07-01
The propagation of a relativistic electron with initial energy ≳100 MeV in a number of simple one-dimensional laser field configurations with circular polarization is studied by solving the relativistic equation of motion in the Landau-Lifschitz approach to account for the radiation friction force. The radiation back-reaction on the electron dynamics becomes visible at dimensionless field amplitudes a ≳ 10 at these high particle energies. Analytical expressions are derived for the energy and the longitudinal momentum of the electron, the frequency shift of the light scattered by the electron and the particle trajectories. These findings are compared with the numerical solutions of the basic equations. A strong radiation damping effect results in reduced light scattering, forming at the same time a broad quasi-continuous spectrum. In addition, the electron dynamics in the strong field of a quasistationary laser piston is investigated. Analytical solutions for the electron trajectories in this complex field pattern are obtained and compared with the numerical solutions. The radiation friction force may stop a relativistic electron after propagation over several laser wavelengths at high laser field strengths, which supports the formation of a stable piston.
Adiabatic modeling of the relativistic electron fluxes during the storm main phase
Kim, H.-J.; Rostoker, G.; Kamide, Y.
Satellite observations have shown that flux variations of outer belt relativistic electrons exhibit a strong radial dependence during the storm main phase. This L dependence can be characterized as small decreases (or at times increases) near the inner edge of the belt and large decreases in its outer region. This paper examines the characteristic radial dependence in terms of the fully adiabatic response of relativistic electrons to magnetic field perturbations. We calculate storm time electron fluxes by adiabatically evolving quiet time values, using Lionville's theorem and the conservation of the three adiabatic invariants. In an adiabatic process, the main phase electron fluxes are affected by the radial structure of magnetic field perturbations and the spatial and energy dependence of the quiet time electron distribution. In response to the field perturbations, adiabatic flux changes become larger at higher L shells where electrons can experience strong deceleration and considerable radial displacement. We conclude that a fully adiabatic treatment can reproduce the overall pattern of the observed radial dependence of relativistic electron fluxes during the storm main phase, although this does not deny the importance of non-adiabatic processes during individual geomagnetic storms.
Relativistic electron kinetic effects on laser diagnostics in burning plasmas
Mirnov, V. V.; Den Hartog, D. J.
2018-02-01
Toroidal interferometry/polarimetry (TIP), poloidal polarimetry (PoPola), and Thomson scattering systems (TS) are major optical diagnostics being designed and developed for ITER. Each of them relies upon a sophisticated quantitative understanding of the electron response to laser light propagating through a burning plasma. Review of the theoretical results for two different applications is presented: interferometry/polarimetry (I/P) and polarization of Thomson scattered light, unified by the importance of relativistic (quadratic in vTe/c) electron kinetic effects. For I/P applications, rigorous analytical results are obtained perturbatively by expansion in powers of the small parameter τ = Te/me c2, where Te is electron temperature and me is electron rest mass. Experimental validation of the analytical models has been made by analyzing data of more than 1200 pulses collected from high-Te JET discharges. Based on this validation the relativistic analytical expressions are included in the error analysis and design projects of the ITER TIP and PoPola systems. The polarization properties of incoherent Thomson scattered light are being examined as a method of Te measurement relevant to ITER operational regimes. The theory is based on Stokes vector transformation and Mueller matrices formalism. The general approach is subdivided into frequency-integrated and frequency-resolved cases. For each of them, the exact analytical relativistic solutions are presented in the form of Mueller matrix elements averaged over the relativistic Maxwellian distribution function. New results related to the detailed verification of the frequency-resolved solutions are reported. The precise analytic expressions provide output much more rapidly than relativistic kinetic numerical codes allowing for direct real-time feedback control of ITER device operation.
Probing SEP Acceleration Processes With Near-relativistic Electrons
International Nuclear Information System (INIS)
Haggerty, Dennis K.; Roelof, Edmond C.
2009-01-01
Processes in the solar corona are prodigious accelerators of near-relativistic electrons. Only a small fraction of these electrons escape the low corona, yet they are by far the most abundant species observed in Solar Energetic Particle events. These beam-like energetic electron events are sometimes time-associated with coronal mass ejections from the western solar hemisphere. However, a significant number of events are observed without any apparent association with a transient event. The relationship between solar energetic particle events, coronal mass ejections, and near-relativistic electron events are better ordered when we classify the intensity time profiles during the duration of the beam-like anisotropies into three broad categories: 1) Spikes (rapid and equal rise and decay); 2) Pulses (rapid rise, slower decay); and 3) Ramps (rapid rise followed by a plateau). We report on the results of a study that is based on our catalog (covering nearly the complete Solar Cycle 23) of 216 near-relativistic electron events and their association with: solar electromagnetic emissions, shocks driven by coronal mass ejections, models of the coronal magnetic fields and energetic protons. We conclude that electron events with time-intensity profiles of Spikes and Pulses are associated with explosive events in the low corona while events with time-intensity profiles of Ramps are associated with the injection/acceleration process of the CME driven shock.
Electron correlation within the relativistic no-pair approximation
DEFF Research Database (Denmark)
Almoukhalalati, Adel; Knecht, Stefan; Jensen, Hans Jørgen Aa
2016-01-01
This paper addresses the definition of correlation energy within 4-component relativistic atomic and molecular calculations. In the nonrelativistic domain the correlation energy is defined as the difference between the exact eigenvalue of the electronic Hamiltonian and the Hartree-Fock energy. In...... scaling of the speed of light is required. This in turn explains why the relativistic correlation energy to the lowest order is not independent of nuclear charge, in contrast to nonrelativistic theory.......This paper addresses the definition of correlation energy within 4-component relativistic atomic and molecular calculations. In the nonrelativistic domain the correlation energy is defined as the difference between the exact eigenvalue of the electronic Hamiltonian and the Hartree-Fock energy....... In practice, what is reported is the basis set correlation energy, where the "exact" value is provided by a full Configuration Interaction (CI) calculation with some specified one-particle basis. The extension of this definition to the relativistic domain is not straightforward since the corresponding...
Forecasting the relativistic electron flux at geosynchronous orbit
Gorney, David J.; Koons, Harry C.
1992-04-01
A neural network, developed to model the temporal variations of relativistic (greater than 3 MeV) electrons at geosynchronous orbit, has been used to make reasonably accurate day-ahead forecasts of the relativistic electron flux at geosynchronous orbit. This model can be used to forecast days when internal discharges might occur on geosynchronous satellites or satellites operating within the outer Van Allen radiation belt. The neural network (in essence, a nonlinear prediction filter) consists of three layers of neurons, containing 10 neurons in the input layer, 6 neurons in a hidden layer, and 1 output neuron. The network inputs consist of ten consecutive days of the daily sum of the planetary magnetic index, Sigma Kp. The output is a prediction of the daily averaged electron flux for the tenth day. The neural network model, together with projections of Sigma Kp based on its historical behavior, can be used to make the day-ahead forecasts of the relativistic electron flux at geosynchronous orbit. A significantly better forecast is obtained by modifying the network to include one additional input, the measured daily averaged electron flux for the day prior to the forecast day, and one more neuron in the hidden layer. Both models are described in this report.
Radiation from systems with relativistic electrons
International Nuclear Information System (INIS)
Ternov, I.M.; Khalilov, V.R.; Bagrov, V.G.; Nikitin, M.M.
1980-01-01
Different methods of generation of electromagnetic radiation in the course of electron motion in external electromagnetic fields are considered. Singularities of ''free electron lasers'' (FEL), synchrotronous, ondulator and Compton radiation sources are discussed. The effect of induced radiation of electrons moving in a magnetic field is studied on the basis of the quantum theory methods. The results obtained are compared with the results of the classical theory. The theoretical and experimental results of the main singularities of the ondulator radiation (OR) are presented. It is shown that when the recoil effects are negligible and nonequidistancy of the energy spectrum of an electron in a magnetic field is of an error character, the results for the dose rate calculated by the quantum and classical theory methods completely coincide in the range of great filling numbers. Both in the quantum and classical theories the effects of the induced radiation of electrons moving in external electromagnetic fields (nonstationary in a general case) of a rather general type depend on two main mechanisms, which are nonequidistancy of the energy spectrum and the recoil effect (the quantum theory); appearance of phase and longitudinal electron bunching under the effect of an alternating radiation field (the classical theory). On the basis of the investigations the conclusion is made that OR can be successfully used for measuring the charged particle beam parameters (dispersion of angular spread and the absolute energy), as well as for measuring the amplitude of the magnetic field intensity in a space-periodic system
Plasma lenses for focusing relativistic electron beams
International Nuclear Information System (INIS)
Govil, R.; Wheeler, S.; Leemans, W.
1997-01-01
The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n p much greater than electron beam density, n b ) or underdense (n p less than 2 n b ). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated
Spin effects in strong-field laser-electron interactions
International Nuclear Information System (INIS)
Ahrens, S; Bauke, H; Müller, T-O; Villalba-Chávez, S; Müller, C
2013-01-01
The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.
Radiative cooling of relativistic electron beams
Energy Technology Data Exchange (ETDEWEB)
Huang, Zhirong [Stanford Univ., CA (United States)
1998-05-01
Modern high-energy particle accelerators and synchrotron light sources demand smaller and smaller beam emittances in order to achieve higher luminosity or better brightness. For light particles such as electrons and positrons, radiation damping is a natural and effective way to obtain low emittance beams. However, the quantum aspect of radiation introduces random noise into the damped beams, yielding equilibrium emittances which depend upon the design of a specific machine. In this dissertation, the author attempts to make a complete analysis of the process of radiation damping and quantum excitation in various accelerator systems, such as bending magnets, focusing channels and laser fields. Because radiation is formed over a finite time and emitted in quanta of discrete energies, he invokes the quantum mechanical approach whenever the quasiclassical picture of radiation is insufficient. He shows that radiation damping in a focusing system is fundamentally different from that in a bending system. Quantum excitation to the transverse dimensions is absent in a straight, continuous focusing channel, and is exponentially suppressed in a focusing-dominated ring. Thus, the transverse normalized emittances in such systems can in principle be damped to the Compton wavelength of the electron, limited only by the Heisenberg uncertainty principle. In addition, he investigates methods of rapid damping such as radiative laser cooling. He proposes a laser-electron storage ring (LESR) where the electron beam in a compact storage ring repetitively interacts with an intense laser pulse stored in an optical resonator. The laser-electron interaction gives rise to rapid cooling of electron beams and can be used to overcome the space charge effects encountered in a medium energy circular machine. Applications to the designs of low emittance damping rings and compact x-ray sources are also explored.
Drozdov, A.; Shprits, Y.; Orlova, K.; Kellerman, A. C.; Subbotin, D.; Baker, D. N.; Spence, H. E.
2014-12-01
In this study, we compare long-term simulations performed by the Versatile Electron Radiation Belt (VERB) code with observations from the MagEIS and REPT instruments on the Van Allen Probes. The model takes into account radial, energy, pitch-angle and mixed diffusion, losses into the atmosphere, and magnetopause shadowing. We consider the energetic (>100 KeV), relativistic (~0.5-1 MeV) and ultra-relativistic (>2 MeV) electrons. One year of relativistic electron measurements (μ=700 MeV/G) from October 1, 2012 to October 1, 2013 are well reproduced by the simulation during a period of the various geomagnetic activity. However, for ultra-relativistic energies (μ=3500 MeV/G), the VERB code simulation overestimates electron phase space density (PSD). These results indicate that an additional loss mechanism is operational and efficient for these high energies. We discuss possible solutions for improving the modeling of the radiation belts dynamics.
Generation and study of relativistic electron beam
International Nuclear Information System (INIS)
Iyyengar, S.K.; Ron, P.H.; Mittal, K.C.; Goel, A.K.; Ramaswamy, V.; Rohatgi, V.K.
1977-01-01
Pulsed Electron Beam (REB) technology has progressed rapidly in recent years because of applications in various fields like radiation sources, high power laser development, plasma heating and fusion research. The REB development programme at the Plasma Physics Section of Bhabha Atomic Research Centre, Bombay, has been described. The design features of the 375 KV, 3500 A, 75 Joule REB generator are discussed. The diagnostic equipment developed for the studies is described. The present experimental studies and some preliminary results on beam characterisation are presented. (author)
Relativistic electron mirrors from high intensity laser nanofoil interactions
International Nuclear Information System (INIS)
Kiefer, Daniel
2012-01-01
The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ 2 , where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those
Relativistic electron mirrors from high intensity laser nanofoil interactions
Energy Technology Data Exchange (ETDEWEB)
Kiefer, Daniel
2012-12-21
The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ{sup 2}, where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those
OTR from Non-Relativistic Electrons
Bal, C; Chevallay, E; Lefèvre, T; Suberlucq, Guy
2003-01-01
The CLIC Test Facility 3 (CTF3) injector will provide pulsed beams of high average current; 5A over 1.56µs at 140keV. For transverse beam sizes of the order of 1mm, as foreseen, this implies serious damage to the commonly used scintillating screens. Optical Transition Radiation from thermally resistant radiators represents a possible alternative. In this context, the backward OTR radiation emitted from an aluminium screen by a 80keV, 60nC, 4ns electron pulse has been investigated. The experimental results are in good agreement with the theoretical expectations, indicating a feeble light intensity distributed over a large solid angle. Our conclusions for the design of the CTF3 injector profile monitor are also given.
Prediction Model for Relativistic Electrons at Geostationary Orbit
Khazanov, George V.; Lyatsky, Wladislaw
2008-01-01
We developed a new prediction model for forecasting relativistic (greater than 2MeV) electrons, which provides a VERY HIGH correlation between predicted and actually measured electron fluxes at geostationary orbit. This model implies the multi-step particle acceleration and is based on numerical integrating two linked continuity equations for primarily accelerated particles and relativistic electrons. The model includes a source and losses, and used solar wind data as only input parameters. We used the coupling function which is a best-fit combination of solar wind/interplanetary magnetic field parameters, responsible for the generation of geomagnetic activity, as a source. The loss function was derived from experimental data. We tested the model for four year period 2004-2007. The correlation coefficient between predicted and actual values of the electron fluxes for whole four year period as well as for each of these years is stable and incredibly high (about 0.9). The high and stable correlation between the computed and actual electron fluxes shows that the reliable forecasting these electrons at geostationary orbit is possible.
Liang, Edison; Fu, Wen; Böttcher, Markus
2017-10-01
We present particle-in-cell simulation results of relativistic shear boundary layers between electron-ion and electron-positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron-positron spine surrounded by a slow-moving or stationary electron-ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. This is in stark contrast to the case of pure electron-ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.
Relativistic collision rate calculations for electron-air interactions
Energy Technology Data Exchange (ETDEWEB)
Graham, G. [EG and G Energy Measurements, Inc., Los Alamos, NM (United States); Roussel-Dupre, R. [Los Alamos National Lab., NM (United States)
1993-12-01
The most recent data available on differential cross sections for electron-air interactions are used to calculate the avalanche, momentum transfer, and energy loss rates that enter into the fluid equations. Data for the important elastic, inelastic, and ionizing processes are generally available out to electron energies of 1--10 keV. Prescriptions for extending these cross sections to the relativistic regime are presented. The angular dependence of the cross sections is included where data are available as is the doubly differential cross section for ionizing collisions. The collision rates are computed by taking moments of the Boltzmann collision integrals with the assumption that the electron momentum distribution function is given by the Juettner distribution function which satisfies the relativistic H- theorem and which reduces to the familiar Maxwellian velocity distribution in the nonrelativistic regime. The distribution function is parameterized in terms of the electron density, mean momentum, and thermal energy and the rates are therefore computed on a two dimensional grid as a function of mean kinetic energy and thermal energy.
Production of plasma from diatomic gases by relativistic electron beams
International Nuclear Information System (INIS)
Cary, J.R.
1980-01-01
The theory of the production of plasma by the interaction of a relativistic electron beam with a diatomic gas is presented. The theory includes atomic species as well as molecular species; this is shown to be necessary when nearly fully ionized plasma are produced. In addition, the theory models magnetic field diffusion by an effective time constant, which allows extensive parameter studies to be performed. The dependence of the production process on the beam intensity and width and the gas pressure is presented. It is shown that the thin beams produced by foil-less diodes are not capable of ionizing high pressure (> or approx. = 3 Torr) targets
Microwave generation and frequency conversion using intense relativistic electron beams
International Nuclear Information System (INIS)
Buzzi, J.M.; Doucet, H.J.; Etlicher, B.
1977-01-01
Some aspects of the microwave generation and frequency conversion by relativistic electron beams are studied. Using an electron synchrotron maser, the excitation of microwaves by an annular relativistic electron beam propagating through a circular wave guide immersed in a longitudinal magnetic field is analyzed. This theoretical model is somewhat more realistic than the previous one because the guiding centers are not on the wave guide axis. Microwave reflection is observed on a R.E.B. front propagating into a gas filled waveguide. The frequency conversion from the incident X-band e.m. waves and the reflected Ka band observed signal is consistent with the Doppler model for β = 0.7. This value agrees with the average beam front velocity as measured from time-of-flight using two B/sub theta/ probes. The reflection is found to occur during the current rise time. With a low impedance device (2 Ω, 400 keV) a GW X-band emission has been observed using thin anodes and a gas filled waveguide. This emission is probably due to the self-fields of the beam and could be used as a diagnostic
Bunch length diagnostics with coherent relativistic electron radiation
Ayzatsky, M I; Kushnir, V A; Mitrochenko, V V
2001-01-01
One of the most important problems when designing resonance electron linacs with a high beam brightness is creation of an equipment for electron bunch length diagnostics. One of ways to solve this problem is based on analysis of radiation from relativistic electrons (transition,synchrotron etc.). The paper presents results of calculations and experiments on studying the millimeter-band radiation that is a beam exited on the surface of the grating periodic structure and in a linac beam pipe. Experiments were carried out on the linac LIC with 13 MeV particle energy and 0.8 A pulse beam current. The possibility of observed radiation application for estimation of the bunch length value, monitoring its variation and for optimization of the accelerator operating mode was shown experimentally.
High frequency electromagnetic modes in a weakly magnetized relativistic electron plasma
International Nuclear Information System (INIS)
Abbas, Gohar; Murtaza, G.; Kingham, R. J.
2010-01-01
Using the linearized Vlasov-Maxwell model, the polarization tensor for a weakly magnetized electron plasma is derived. For isotropic relativistic Maxwellian velocity distribution function, dispersion relations are obtained for both parallel and perpendicular propagations. The integrals (called Meijer G functions) that arise due to relativistic effects are examined in various limits and dispersion relations are derived for the nonrelativistic, weakly, strongly, and ultrarelativistic Maxwellian velocity distributions. It is generally observed that the propagation domains of the modes are enlarged as one proceeds from the nonrelativistic to the highly relativistic regime. Resultantly, due to the relativistic effects, the Whistler mode is suppressed in the R-wave, the nonpropagation band of X-mode is reduced, and the X-mode itself approaches the O-mode. Further, the results derived in the ultra- and nonrelativistic limits found to be in agreement with the earlier calculations [G. Abbas et al. Phys. Scr. 76, 649 (2007); F. F. Chen, Introduction to Plasma Physics and Controlled Fusion (Plenum, New York, 1984), Vol. 1].
Relativistic electronic dressing in laser-assisted ionization of atomic hydrogen by electron impact
International Nuclear Information System (INIS)
Attaourti, Y.; Taj, S.
2004-01-01
Within the framework of the coplanar binary geometry where it is justified to use plane wave solutions for the study of the (e,2e) reaction and in the presence of a circularly polarized laser field, we introduce as a first step the Dirac-Volkov plane wave Born approximation 1 where we take into account only the relativistic dressing of the incident and scattered electrons. Then, we introduce the Dirac-Volkov plane wave Born approximation 2 where we take totally into account the relativistic dressing of the incident, scattered, and ejected electrons. We then compare the corresponding triple differential cross sections for laser-assisted ionization of atomic hydrogen by electron impact both for the nonrelativistic and the relativistic regime
Linear theory of a cold relativistic beam in a strongly magnetized finite-geometry plasma
International Nuclear Information System (INIS)
Gagne, R.R.J.; Shoucri, M.M.
1976-01-01
The linear theory of a finite-geometry cold relativistic beam propagating in a cold homogeneous finite-geometry plasma, is investigated in the case of a strongly magnetized plasma. The beam is assumed to propagate parallel to the external magnetic field. It is shown that the instability which takes place at the Cherenkov resonance ωapprox. =k/subz/v/subb/ is of the convective type. The effect of the finite geometry on the instability growth rate is studied and is shown to decrease the growth rate, with respect to the infinite geometry, by a factor depending on the ratio of the beam-to-plasma radius
Nonuniform currents and spins of relativistic electron vortices in a magnetic field
van Kruining, Koen; Hayrapetyan, Armen G.; Götte, Jörg B.
2017-01-01
We present a relativistic description of electron vortex beams in a homogeneous magnetic field. Including spin from the beginning reveals that spin-polarized electron vortex beams have a complicated azimuthal current structure, containing small rings of counterrotating current between rings of stronger corotating current. Contrary to many other problems in relativistic quantum mechanics, there exists a set of vortex beams with exactly zero spin-orbit mixing in the highly relativistic and nonp...
Roy, Soumendra K.; Jian, Tian; Lopez, Gary V.; Li, Wei-Li; Su, Jing; Bross, David H.; Peterson, Kirk A.; Wang, Lai-Sheng; Li, Jun
2016-02-01
The observation of the gaseous UFO- anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO- is linear with an O-U-F structure and a 3H4 spectral term derived from a U 7sσ25fφ15fδ1 electron configuration, whereas the ground state of neutral UFO has a 4H7/2 spectral term with a U 7sσ15fφ15fδ1 electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.
Ion response to relativistic electron bunches in the blowout regime of laser-plasma accelerators.
Popov, K I; Rozmus, W; Bychenkov, V Yu; Naseri, N; Capjack, C E; Brantov, A V
2010-11-05
The ion response to relativistic electron bunches in the so called bubble or blowout regime of a laser-plasma accelerator is discussed. In response to the strong fields of the accelerated electrons the ions form a central filament along the laser axis that can be compressed to densities 2 orders of magnitude higher than the initial particle density. A theory of the filament formation and a model of ion self-compression are proposed. It is also shown that in the case of a sharp rear plasma-vacuum interface the ions can be accelerated by a combination of three basic mechanisms. The long time ion evolution that results from the strong electrostatic fields of an electron bunch provides a unique diagnostic of laser-plasma accelerators.
Evidence for acceleration of outer zone electrons to relativistic energies by whistler mode chorus
Directory of Open Access Journals (Sweden)
N. P. Meredith
2002-07-01
Full Text Available We use plasma wave and electron data from the Combined Release and Radiation Effects Satellite (CRRES to investigate the viability of a local stochastic electron acceleration mechanism to relativistic energies driven by gyroresonant interactions with whistler mode chorus. In particular, we examine the temporal evolution of the spectral response of the electrons and the waves during the 9 October 1990 geomagnetic storm. The observed hardening of the electron energy spectra over about 3 days in the recovery phase is coincident with prolonged substorm activity, as monitored by the AE index and enhanced levels of whistler mode chorus waves. The observed spectral hardening is observed to take place over a range of energies appropriate to the resonant energies associated with Doppler-shifted cyclotron resonance, as supported by the construction of realistic resonance curves and resonant diffusion surfaces. Furthermore, we show that the observed spectral hardening is not consistent with energy-independent radial diffusion models. These results provide strong circumstantial evidence for a local stochastic acceleration mechanism, involving the energisation of a seed population of electrons with energies of the order of a few hundred keV to relativistic energies, driven by wave-particle interactions involving whistler mode chorus. The results suggest that this mechanism contributes to the reformation of the relativistic outer zone population during geomagnetic storms, and is most effective when the recovery phase is characterised by prolonged substorm activity. An additional significant result of this paper is that we demonstrate that the lower energy part of the storm-time electron distribution is in steady-state balance, in accordance with the Kennel and Petschek (1966 theory of limited stably-trapped particle fluxes.Key words. Magnetospheric physics (storms and substorms, energetic particles, trapped – Space plasma physics (wave-particle interactions
Electronic Structure of Strongly Correlated Materials
Anisimov, Vladimir
2010-01-01
Electronic structure and physical properties of strongly correlated materials containing elements with partially filled 3d, 4d, 4f and 5f electronic shells is analyzed by Dynamical Mean-Field Theory (DMFT). DMFT is the most universal and effective tool used for the theoretical investigation of electronic states with strong correlation effects. In the present book the basics of the method are given and its application to various material classes is shown. The book is aimed at a broad readership: theoretical physicists and experimentalists studying strongly correlated systems. It also serves as a handbook for students and all those who want to be acquainted with fast developing filed of condensed matter physics.
Relativistic light-shift theory of few-electron systems: Heliumlike highly charged ions
Postavaru, O.; Scafes, A. C.
2017-09-01
The light-shift theory of many-electron systems in a laser field is described using the projection operators technique. In heavy ions, the electrons are tightly bound by the Coulomb potential of the nucleus, which prohibits ionization even by strong lasers. However, interaction with the monofrequent laser field leads to dynamic shifts of the electronic energy levels, and the process is treated by second-order time-dependent perturbation theory. In order to treat heliumlike systems, one decomposes the corresponding matrix elements into hydrogenlike matrix elements using the independent particle model. We are applying a fully relativistic description of the electronic states by means of the Dirac equation. Our formalism goes beyond the Stark long-wavelength dipole approximation and takes into account nondipole effects of retardation and interaction with the magnetic field components of the laser beam.
Relativistic Turbulence with Strong Synchrotron and Synchrotron-Self-Compton Cooling
Uzdensky, D. A.
2018-03-01
Many relativistic plasma environments in high-energy astrophysics, including pulsar wind nebulae, hot accretion flows onto black holes, relativistic jets in active galactic nuclei and gamma-ray bursts, and giant radio lobes, are naturally turbulent. The plasma in these environments is often so hot that synchrotron and inverse-Compton (IC) radiative cooling becomes important. In this paper we investigate the general thermodynamic and radiative properties (and hence the observational appearance) of an optically thin relativistically hot plasma stirred by driven magnetohydrodynamic (MHD) turbulence and cooled by radiation. We find that if the system reaches a statistical equilibrium where turbulent heating is balanced by radiative cooling, the effective electron temperature tends to attain a universal value θ = kT_e/m_e c^2 ˜ 1/√{τ_T}, where τT = neσTL ≪ 1 is the system's Thomson optical depth, essentially independent of the strength of turbulent driving and hence of the magnetic field. This is because both MHD turbulent dissipation and synchrotron cooling are proportional to the magnetic energy density. We also find that synchrotron self-Compton (SSC) cooling and perhaps a few higher-order IC components are automatically comparable to synchrotron in this regime. The overall broadband radiation spectrum then consists of several distinct components (synchrotron, SSC, etc.), well separated in photon energy (by a factor ˜ τ_T^{-1}) and roughly equal in power. The number of IC peaks is checked by Klein-Nishina effects and depends logarithmically on τT and the magnetic field. We also examine the limitations due to synchrotron self-absorption, explore applications to Crab PWN and blazar jets, and discuss links to radiative magnetic reconnection.
Highly relativistic magnetospheric electrons: A role in coupling to the middle atmosphere?
International Nuclear Information System (INIS)
Baker, D.N.; Blake, J.B.; Gorney, D.J.; Higbie, P.R.; Klebesadel, R.W.; King, J.H.
1987-01-01
Long-term (1979-present) observations of relativistic electrons (2--15 MeV) at geostationary orbit show a strong solar cycle dependence. Such electrons were largely absent near the last solar maximum (1979--80), while they were prominent during the approach to solar minimum (1983--85). This population now is dwindling as solar minimum has been reached. The strong magnetospheric presence of high-speed solar wind streams which results from solar coronal hole structures during the approach to solar activity (sunspot) minimum. We clearly observe 27-day periodic enhancements of the relativistic electrons in association with concurrently measured solar wind streams (V/sub S//sub W/approx. >600 km/s). We have used a numerical transport code to study the coupling of these high-energy electrons to earth's upper and middle atmosphere. We calculate using the observed energy spectra of the electrons that, when precipitated, these electrons show a large (maximum of ∼100 keV/cm 3 -s) energy deposition at 40--60 km altitude, which is 3--4 orders of magnitude greater than the galactic cosmic ray or solar EUV energy deposition at these altitudes. We also find that the global energy deposition in the mid-latitudes totals nearly 10 21 ergs for a typical 2--3 day event period. We conclude that this previously unrecognized electron population could play an important role in coupling solar wind and magnetospheric variability (on 27--day and 11--year cycles) to the middle atmosphere through a modulating effect on lower D-region ionization and, possibly, on upper level ozone chemistry. These electrons also may contribute to the recent Antarctic polar ozone depletion phenomenon. copyright American Geophysical Union 1987
Laser-driven relativistic electron dynamics in a cylindrical plasma channel
Geng, Pan-Fei; Lv, Wen-Juan; Li, Xiao-Liang; Tang, Rong-An; Xue, Ju-Kui
2018-03-01
The energy and trajectory of the electron, which is irradiated by a high-power laser pulse in a cylindrical plasma channel with a uniform positive charge and a uniform negative current, have been analyzed in terms of a single-electron model of direct laser acceleration. We find that the energy and trajectory of the electron strongly depend on the positive charge density, the negative current density, and the intensity of the laser pulse. The electron can be accelerated significantly only when the positive charge density, the negative current density, and the intensity of the laser pulse are in suitable ranges due to the dephasing rate between the wave and electron motion. Particularly, when their values satisfy a critical condition, the electron can stay in phase with the laser and gain the largest energy from the laser. With the enhancement of the electron energy, strong modulations of the relativistic factor cause a considerable enhancement of the electron transverse oscillations across the channel, which makes the electron trajectory become essentially three-dimensional, even if it is flat at the early stage of the acceleration. Project supported by the National Natural Science Foundation of China (Grant Nos. 11475027, 11765017, 11764039, 11305132, and 11274255), the Natural Science Foundation of Gansu Province, China (Grant No. 17JR5RA076), and the Scientific Research Project of Gansu Higher Education, China (Grant No. 2016A-005).
Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.
Shprits, Yuri Y; Drozdov, Alexander Y; Spasojevic, Maria; Kellerman, Adam C; Usanova, Maria E; Engebretson, Mark J; Agapitov, Oleksiy V; Zhelavskaya, Irina S; Raita, Tero J; Spence, Harlan E; Baker, Daniel N; Zhu, Hui; Aseev, Nikita A
2016-09-28
The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes.
Novel x-ray source using collisions of circulating relativistic electrons and a wire target
International Nuclear Information System (INIS)
Yamada, Hironari
1995-01-01
The novel method for generating brilliant x-ray beams is proposed, in which inelastic collisions of circulating relativistic electrons and a thin wire target are used. High brilliance of this new photon source stands on narrow angular divergence due to the kinematics of relativistic electrons, and repeatedly use of electron beams. The estimated brilliance of this source based on a 50 MeV electron storage ring is comparable to that of compact synchrotron light sources. (author)
Nonlinear Electron Waves in Strongly Magnetized Plasmas
DEFF Research Database (Denmark)
Pécseli, Hans; Juul Rasmussen, Jens
1980-01-01
Weakly nonlinear dispersive electron waves in strongly magnetized plasma are considered. A modified nonlinear Schrodinger equation is derived taking into account the effect of particles resonating with the group velocity of the waves (nonlinear Landau damping). The possibility of including the ion...
Superdiffusion of relativistic electrons at supernova remnant shocks
Perri, Silvia
2018-01-01
Anomalous transport has been observed in various systems as nonlinear systems, numerical simulations of plasma turbulence, in laboratory plasmas, and recently in the propagation of energetic particles in the interplanetary space. Thanks to in situ observations it has been possible to deduce transport properties directly from spacecraft data. This technique has further found applicability to remote observations of relativistic electrons accelerated at supernova remnants (SNRs) shocks, pointing out that far upstream of the blast waves, the x-ray synchrotron emission, as captured by the Chandra spacecraft, is consistent with models of superdiffusive transport (i.e., transport faster than normal diffusive). Here we present and summarize evidences of superdiffusion both in the interplanetary space and upstream of SNRs shock fronts, in particular by analyzing, for the first time in the framework of superdiffusion, the transport properties of electrons accelerated at the young G1.9+0.3 SNR. We also briefly describe how this new model can be used to interpret radio emissions from electrons accelerated at shocks forming during galaxy cluster mergers.
On the limiting stationary currents of relativistic electron beams
International Nuclear Information System (INIS)
Kavchuk, V.N.; Kondratenko, A.N.
1987-01-01
The problem on electron beam transport in the system of different configurations both vacuum and filled with gas or plasma is connected with the problem of the limiting current, which can conduct such systems. Two models of a vacuum relativistic electron beam (REB) are considered. It is shown that there is upper limit for the value of the external magnetic field, H 0 , in the model of isovelocity REB with the constant longitudinal beam particle rate, β z =const. Estimation of the limiting current of REB as a series of inverse power H 0 is obtained. Estimations of the limiting current of magnetized hallow REB with thin walls are obtained in another model with β z ≠ const. Determination used in this case of the limiting current is directly connected with ''trapping'' of the beam central part due to formation of a virtual cathode and based on consideration of uniflux electron motion in the beam. Such an approach allows to obtain estimations of the limiting current of the thin-wall hallow beam. In this case an upper limit for the thickness of the beam wall is connected with the bottom limit for the value of the external magnetic field providing radial beam equilibrium
Precipitation of relativistic electrons of the Van Allen belts into the proton aurora
Energy Technology Data Exchange (ETDEWEB)
Jordanova, Vania K [Los Alamos National Laboratory; Miyoshi, Y [NAGOYA UNIV; Sakaguchi, K [NAGOYA UNIV; Shiokawa, K [NAGOYA UNIV; Evans, D S [SEC/NOAA; Albert, Jay [AFRL; Connors, M [UNIV OF ATHABASCA
2008-01-01
The Van Allen electron belts consist of two regions encircling the earth in which relativistic electrons are trapped in the earth's magnetic field. Populations of relativistic electrons in the Van Allen belts vary greatly with geomagnetic disturbance and they are a major source of damage to space vehicles. In order to know when and by how much these populations of relativistic electrons increase, it is important to elucidate not only the cause of acceleration of relativistic electrons but also the cause of their loss from the Van Allen belts. Here we show the first evidence that left-hand polarized electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere, on the basis of results of an excellent set of ground and satellite observations showing coincident precipitation of ions with energies of tens of keV and of relativistic electrons into an isolated proton aurora. The proton aurora was produced by precipitation of ions with energies of tens of keV due to EMIC waves near the plasma pause, which is a manifestation of wave-particle interactions. These observations clarify that ions with energies of tens of keV affect the evolution of relativistic electrons in the Van Allen belts via parasitic resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.
Popa, Alexandru; Stancalie, Viorica
2017-06-01
In a series of previous papers we proved an accurate connection between quantum and classical equations in the case of electrodynamic systems. We have used this connection to elaborate simplified models for systems composed of very intense laser beams and electrons or atoms. These models are in good agreement with numerous experimental data from literature. In this paper we develop the above approach for the new field of interactions between ultraintense laser beams, having intensities in the range 1018 - 1022 W/cm2, and electron plasmas. We show that in this case new effects take place, such as the fact that the variation of the phase of the field at the point where the electron is situated, decreases when the intensity of the field increases, due to a strong relativistic behavior. This effect leads to an aperiodic behavior of the radiations generated by above interactions, and to a possible new method for solitary waves generation.
Ion-acoustic envelope modes in a degenerate relativistic electron-ion plasma
Energy Technology Data Exchange (ETDEWEB)
McKerr, M.; Kourakis, I. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN Belfast, Northern Ireland (United Kingdom); Haas, F. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS (Brazil)
2016-05-15
A self-consistent relativistic two-fluid model is proposed for one-dimensional electron-ion plasma dynamics. A multiple scales perturbation technique is employed, leading to an evolution equation for the wave envelope, in the form of a nonlinear Schrödinger type equation (NLSE). The inclusion of relativistic effects is shown to introduce density-dependent factors, not present in the non-relativistic case—in the conditions for modulational instability. The role of relativistic effects on the linear dispersion laws and on envelope soliton solutions of the NLSE is discussed.
Silicon nanowire based high brightness, pulsed relativistic electron source
Directory of Open Access Journals (Sweden)
Deep Sarkar
2017-06-01
Full Text Available We demonstrate that silicon nanowire arrays efficiently emit relativistic electron pulses under irradiation by a high-intensity, femtosecond, and near-infrared laser (∼1018 W/cm2, 25 fs, 800 nm. The nanowire array yields fluxes and charge per bunch that are 40 times higher than those emitted by an optically flat surface, in the energy range of 0.2–0.5 MeV. The flux and charge yields for the nanowires are observed to be directional in nature unlike that for planar silicon. Particle-in-cell simulations establish that such large emission is caused by the enhancement of the local electric fields around a nanowire, which consequently leads to an enhanced absorption of laser energy. We show that the high-intensity contrast (ratio of picosecond pedestal to femtosecond peak of the laser pulse (10−9 is crucial to this large yield. We extend the notion of surface local-field enhancement, normally invoked in low-order nonlinear optical processes like second harmonic generation, optical limiting, etc., to ultrahigh laser intensities. These electron pulses, expectedly femtosecond in duration, have potential application in imaging, material modification, ultrafast dynamics, terahertz generation, and fast ion sources.
Impact of Relativistic Electron Beam on Hole Acoustic Instability in Quantum Semiconductor Plasmas
Siddique, M.; Jamil, M.; Rasheed, A.; Areeb, F.; Javed, Asif; Sumera, P.
2018-01-01
We studied the influence of the classical relativistic beam of electrons on the hole acoustic wave (HAW) instability exciting in the semiconductor quantum plasmas. We conducted this study by using the quantum-hydrodynamic model of dense plasmas, incorporating the quantum effects of semiconductor plasma species which include degeneracy pressure, exchange-correlation potential and Bohm potential. Analysis of the quantum characteristics of semiconductor plasma species along with relativistic effect of beam electrons on the dispersion relation of the HAW is given in detail qualitatively and quantitatively by plotting them numerically. It is worth mentioning that the relativistic electron beam (REB) stabilises the HAWs exciting in semiconductor (GaAs) degenerate plasma.
Pokhotelov, D.; Rae, I. J.; Murphy, K. R.; Mann, I. R.
2016-12-01
Electromagnetic ultralow-frequency (ULF) waves are known to play a substantial role in radial transport, acceleration, and loss of relativistic particles trapped in the Earth's outer radiation belt. Using in situ observations by multiple spacecraft operating in the vicinity of outer radiation belts, we analyze the temporal and spatial behavior of ULF waves throughout the geomagnetic storm of 8-9 October 2012 and compare with the dynamics of relativistic electron fluxes on board the twin Van Allen Probes spacecraft. The analysis shows that the relativistic electron fluxes reduce from their prestorm levels during the first phase of the storm and rapidly increase during the second phase of the storm. We demonstrate that the behavior of ULF wave power changes throughout the storm, from ULF oscillations being a mixture of compressional and shear magnetic components during the first phase of the storm to ULF oscillations being dominated by transverse (shear) components during the second phase. We analyze the parameters of ULF-driven radial diffusion throughout the storm and compare the observed diffusion coefficients with their statistical averages. We demonstrate that the observed diffusion coefficients are strong enough to impact the redistribution of relativistic electron fluxes from and to the outer boundary of radiation belts and the diffusion might influence the effects of any local electron acceleration by transporting fluxes inward or outward according to phase space density gradients.
Intense relativistic electron beam injector system for tokamak current drive
International Nuclear Information System (INIS)
Bailey, V.L.; Creedon, J.M.; Ecker, B.M.; Helava, H.I.
1983-01-01
We report experimental and theoretical studies of an intense relativistic electron beam (REB) injection system designed for tokamak current drive experiments. The injection system uses a standard high-voltage pulsed REB generator and a magnetically insulated transmission line (MITL) to drive an REB-accelerating diode in plasma. A series of preliminary experiments has been carried out to test the system by injecting REBs into a test chamber with preformed plasma and applied magnetic field. REBs were accelerated from two types of diodes: a conventional vacuum diode with foil anode, and a plasma diode, i.e., an REB cathode immersed in the plasma. REB current was in the range of 50 to 100 kA and REB particle energy ranged from 0.1 to 1.0 MeV. MITL power density exceeded 10 GW/cm 2 . Performance of the injection system and REB transport properties is documented for plasma densities from 5 x 10 12 to 2 x 10 14 cm -3 . Injection system data are compared with numerical calculations of the performance of the coupled system consisting of the generator, MITL, and diode
X-ray emission from relativistically moving electron density cusps
International Nuclear Information System (INIS)
Kando, M.; Pirozhkov, A. S.; Nakamura, T.; Hayashi, Y.; Kotaki, H.; Kawase, K.; Esirkepov, T. Zh.; Fukuda, Y.; Kiriyama, H.; Okada, H.; Daito, I.; Kameshima, T.; Mori, M.; Koga, J. K.; Daido, H.; Faenov, A. Ya.; Pikuz, T.; Ma, J.; Chen, L.-M.; Ragozin, E. N.
2012-01-01
We report on novel methods to generate ultra-short, coherent, X-rays using a laserplasma interaction. Nonlinear interaction of intense laser pulses with plasma creates stable, specific structures such as electron cusps. For example, wake waves excited in an underdense plasma by an intense, short-pulse laser become dense and propagate along with the laser pulse. This is called a relativistic flying mirror. The flying mirror can reflect a counter-propagating laser pulse and directly convert it into high-frequency radiation, with a frequency multiplication factor of ∼ 4γ 2 and pulse shortening with the same factor. After the proof-of-principle experiments, we observed that the photon number generated in the flying mirror is close to the theoretical estimate. We present the details of the experiment in which a 9 TW laser pulse focused into a He gas jet generated the Flying Mirror, which partly reflected a 1 TW pulse, giving up to ∼ 10 10 photons, 60 nJ (1.4×10 12 photons/sr) in the XUV spectral region (12.8-22 nm).
Ground pulsation magnetometer observations conjugated with relativistic electron precipitation
Yahnin, A. G.; Yahnina, T. A.; Raita, T.; Manninen, J.
2017-09-01
In this report, we investigate the role of electromagnetic ion cyclotron (EMIC) waves in production of relativistic electron precipitation (REP). Over a thousand REP events were detected from four NOAA Polar-orbiting Operational Environmental Satellites in July-December 2005. Of these, a total of 112 events were conjugated with a ground-based network of six Finnish induction coil magnetometers and one in Lovozero observatory at Kola Peninsula, Russia. The observation of geomagnetic pulsations during the conjugated events showed that about one third of them were accompanied by pulsations in the Pc1 range, which are the signature of EMIC waves. In fact, the sources of some of these EMIC waves were well outside the location of the REP event. This means that in such cases the REP events were not originated from scattering by EMIC waves. Finally, it is concluded that for this limited set of conjugated events only a quarter might be related to scattering by EMIC waves. The majority of the events are not correlated with EMIC wave signatures in ground-based observations; they were associated with either no pulsations or noise-like pulsations PiB and PiC.
X-ray emission from relativistically moving electron density cusps
Energy Technology Data Exchange (ETDEWEB)
Kando, M.; Pirozhkov, A. S.; Nakamura, T.; Hayashi, Y.; Kotaki, H.; Kawase, K.; Esirkepov, T. Zh.; Fukuda, Y.; Kiriyama, H.; Okada, H.; Daito, I.; Kameshima, T.; Mori, M.; Koga, J. K.; Daido, H.; Faenov, A. Ya.; Pikuz, T.; Ma, J.; Chen, L.-M.; Ragozin, E. N. [Japan Atomic Energy Agency (Japan); Osaka University (Japan); Joint Institute for High Temperature of the Russian Academy of Science, Moscow (Russian Federation); Institute of Physics, Chinese Academy of Sciences, Beijing (China); P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Leninsky prospekt 53, 119991 Moscow (Russian Federation); Japan Atomic Energy Agency and Graduate School for the Creation of New Photonics Industries (Japan); Ludwig-Maximilians-University (Germany); and others
2012-07-11
We report on novel methods to generate ultra-short, coherent, X-rays using a laserplasma interaction. Nonlinear interaction of intense laser pulses with plasma creates stable, specific structures such as electron cusps. For example, wake waves excited in an underdense plasma by an intense, short-pulse laser become dense and propagate along with the laser pulse. This is called a relativistic flying mirror. The flying mirror can reflect a counter-propagating laser pulse and directly convert it into high-frequency radiation, with a frequency multiplication factor of {approx} 4{gamma}{sup 2} and pulse shortening with the same factor. After the proof-of-principle experiments, we observed that the photon number generated in the flying mirror is close to the theoretical estimate. We present the details of the experiment in which a 9 TW laser pulse focused into a He gas jet generated the Flying Mirror, which partly reflected a 1 TW pulse, giving up to {approx} 10{sup 10} photons, 60 nJ (1.4 Multiplication-Sign 10{sup 12} photons/sr) in the XUV spectral region (12.8-22 nm).
NMR study of strongly correlated electron systems
Kitaoka, Y.; Tou, H.; Zheng, G.-q.; Ishida, K.; Asayama, K.; Kobayashi, T. C.; Kohda, A.; Takeshita, N.; Amaya, K.; Onuki, Y.; Geibel, G.; Schank, C.; Steglich, F.
1995-02-01
Various types of ground states in strongly correlated electron systems have been systematically investigated by means of NMR/NQR at low temperatures under high magnetic field and pressure. We focus on two well-known heavy-electron families, CeCu 2X 2 (X = Si and Ge) (Ce(122)) and UM 2Al 3 (M = Ni and Pd) (U(123)). The Cu NQR experiments on CeCu 2X 2 under high pressure indicate that the physical property of CeCu 2Ge 2 at high pressure, i.e. above the transition at 7.6 GPa from antiferromagnetic (AF) to superconductivity, are clearly related to tha CeCu 2Si 2 at ambient pressure. In addition to the H-T phase diagram established below 7 T, NMR and specific heat experiments on polycrystal CeCu 2.05Si 2 have revealed the presence of a new phase above 7 T. In a high-quality polycrystal of UPd 2Al 3 with a record high- Tc of 2 K at ambient pressure and the narrowest Al NQR line width, the nuclear-spin lattice relaxation rate, 27(1/ T1) measured in zero field has been found to obey the T3 law down to 0.13 K, giving strong evidence that the energy gap vanishes along lines on the Fermi surface. Thus it seems that all heavy-electron superconductors exhibit lines of zero gap, regardless of their different magnetic properties.
Proposal for the study of laminar relativistic electron beam generation by a foilless diode
International Nuclear Information System (INIS)
Jones, M.E.; Thode, L.E.
1979-02-01
The continuation of an analytical and numerical study of intense relativistic electron beam generation by foilless diodes is proposed. The investigation is aimed at optimizing the diode design to produce a laminar flow
Manifestation of sleeping-instability in partially-compensated relativistic electron beams
International Nuclear Information System (INIS)
Karbushev, N.I.; Rukhadze, A.A.; Udivichenko, S.Yu.
1984-01-01
Problem of sleeping-instability in partially-compensated relativistic electron beam is exactly solved for the ring waveguide. Nonuniformity of beam velocity is conditioned by electrostatic potential sagging
The Work Function Associated with Ultra-relativistic Electron ...
Indian Academy of Sciences (India)
1928), driven by electro-static force at the poles, produced by the strong magnetic field of rotating neutron stars. The work function plays a major role in the emission processes. Moreover, it is interesting to note that electrons are only emitted from the polar region of magnetized neutron stars, but never from some region far ...
International Nuclear Information System (INIS)
Kato, K.G.; Benford, G.; Tzach, D.
1983-01-01
Prodigious quantities of microwave energy are observed uniformly across a wide frequency band when a relativistic electron beam (REB) penetrates a plasma. Measurement calculations are illustrated. A model of Compton-like boosting of ambient plasma waves by beam electrons, with collateral emission of high frequency photons, qualitatively explain the spectra. A transition in spectral behavior is observed from the weak to strong turbulence theories advocated for Type III solar burst radiation, and further into the regime the authors characterize as super-strong REB-plasma interactions
M. Füllekrug; C. Hanuise; M. Parrot
2010-01-01
Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which observes 100 kHz ...
Relativistic effects on the modulational instability of electron plasma ...
Indian Academy of Sciences (India)
This is justified as we are considering ultra-cold plasma with weakly relativistic effect. Moreover, it must also be kept in mind that the quantum relativistic plasma is a growing field of research in which models are also being developed. We now use the following normalization: x → xωpe/VFe, t → tωpe, φ → eφ/2kBTFe, nj → nj ...
Theoretical study of relativistic effects in the electronic structure and chemical bonding of UF6
International Nuclear Information System (INIS)
Onoe, Jun; Takeuchi, Kazuo; Sekine, Rika; Nakamatsu, Hirohide; Mukoyama, Takeshi; Adachi, Hirohiko.
1992-01-01
We have performed the relativistic molecular orbital calculation for the ground state of UF 6 , using the discrete-variational Dirac-Slater method (DV-DS), in order to elucidate the relativistic effects in the electronic structure and chemical bonding. Compared with the electronic structure calculated by the non-relativistic Hartree-Fock-Slater (DV-X α )MO method, not only the direct relativistic effects (spin-orbit splitting etc), but also the indirect effect due to the change in screening core potential charge are shown to be important in the MO level structure. From the U-F bond overlap population analysis, we found that the U-F bond formation can be explained only by the DV-DS, not by the DV-X α . The calculated electronic structure in valence energy region (-20-OeV) and excitation energies in UV region are in agreement with experiments. (author)
Magnetic Field Generation and Electron Acceleration in Relativistic Laser Channel
International Nuclear Information System (INIS)
Kostyukov, I.Yu.; Shvets, G.; Fisch, N.J.; Rax, J.M.
2001-01-01
The interaction between energetic electrons and a circularly polarized laser pulse inside an ion channel is studied. Laser radiation can be resonantly absorbed by electrons executing betatron oscillations in the ion channel and absorbing angular momentum from the laser. The absorbed angular momentum manifests itself as a strong axial magnetic field (inverse Faraday effect). The magnitude of this magnetic field is calculated and related to the amount of the absorbed energy. Absorbed energy and generated magnetic field are estimated for the small and large energy gain regimes. Qualitative comparisons with recent experiments are also made
Roy, Soumendra K; Jian, Tian; Lopez, Gary V; Li, Wei-Li; Su, Jing; Bross, David H; Peterson, Kirk A; Wang, Lai-Sheng; Li, Jun
2016-02-28
The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO(-) is linear with an O-U-F structure and a (3)H4 spectral term derived from a U 7sσ(2)5fφ(1)5fδ(1) electron configuration, whereas the ground state of neutral UFO has a (4)H(7/2) spectral term with a U 7sσ(1)5fφ(1)5fδ(1) electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.
Resonance effects in projectile-electron loss in relativistic collisions with excited atoms
International Nuclear Information System (INIS)
Voitkiv, A B
2005-01-01
The theory of electron loss from projectile-ions in relativistic ion-atom collisions is extended to the case of collisions with excited atoms. The main feature of such collisions is a resonance which can emerge between electron transitions in the ion and atom. The resonance becomes possible due to the Doppler effect and has a well-defined impact energy threshold. In the resonance case, the ion-atom interaction is transmitted by the radiation field and the range of this interaction becomes extremely long. Because of this the presence of other atoms in the target medium and the size of the space occupied by the medium have to be taken into account and it turns out that microscopic loss cross sections may be strongly dependent on such macroscopic parameters as the target density, temperature and size. We consider both the total and differential loss cross sections and show that the resonance can have a strong impact on the angular and energy distributions of electrons emitted from the projectiles and the total number of electron loss events
International Nuclear Information System (INIS)
Kato, K.
1986-09-01
Mildly relativistic electron velocity distributions are diagnosed from measurements of the first few electron cyclotron emission harmonics in the Alcator C tokamak. The approach employs a vertical viewing chord through the center of the tokamak plasma terminating at a compact, high-performance viewing dump. The cyclotron emission spectra obtained in this way are dominated by frequency downshifts due to the relativistic mass increase, which discriminates the electrons by their total energy. In this way a one-to-one correspondence between the energy and the emission frequency is accomplished in the absence of harmonic superpositions. The distribution, described by f/sub p/, the line-averaged phase space density, and Λ, the anisotropy factor, is determined from the ratio of the optically thin harmonics or polarizations. Diagnosis of spectra in the second and the third harmonic range of frequencies obtained during lower hybrid heating, current drive, and low density ohmic discharges are carried out, using different methods depending on the degree of harmonic superposition present in the spectrum and the availability of more than one ratio measurement. Discussions of transient phenomena, the radiation temperature measurement from the optically thick first harmonic, and the measurements compared to the angular hard x-ray diagnostic results illuminate the capabilities of the vertically viewing electron cyclotron emission diagnostic
Spatial Extent of Relativistic Electron Precipitation from the Radiation Belts
Shekhar, Sapna
Relativistic Electron Precipitation (REP) in the atmosphere can contribute signi- cantly to electron loss from the outer radiation belts. In order to estimate the contribution to this loss, it is important to estimate the spatial extent of the precipitation region. We observed REP with the 0° Medium Energy Proton Electron Detector (MEPED) on board Polar Orbiting Environmental Satellites (POES), for 15 years (2000-2014) and used both single and multi satellite measurements to estimate an average extent of the region of precipitation in L shell and Magnetic Local Time. In the duration of 15 years (2000-2014), 31035 REPs were found in this study. Events were found to split into two classes; one class of events coincided with proton precipitation in the P1 channel (30-80 keV), were located in the dusk and early morning sector, and were more localized in L shell and magnetic local time (dMLT 0-3 hrs, dL 0.25-0.5),whereas the other class of events did not include proton precipitation, and were located mostly in the midnight sector and were wider in L shell (dL 1-2.5) but localized in MLT (dMLT 0-3 hrs); both classes occurred mostly during the declining phase of the solar cycle and geomagnetically active times. The events located in the midnight sector for both classes were found to be associated with tail magnetic field stretching which could be due to the fact that they tend to occur mostly during geomagnetically active times, or could imply that precipitation is caused by current sheet scattering. Use of POES to infer information about the precipitation energy spectrum was also investigated, despite the coarse energy channels and contamination issues. In order to study the energy specicity of the REP events, a method to t exponential spectra to the REP events, wherever possible, was formulated and validated through comparisons with SAMPEX observed spectra. 18 events on POES were found to be in conjunction with SAMPEX in the years 2000-04. The exponentially tted
Tang, C. L.; Wang, Y. X.; Ni, B.; Su, Z. P.; Reeves, G. D.; Zhang, J.-C.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.
2017-10-01
Using the electron phase space density (PSD) data measured by Van Allen Probe A from January 2013 to April 2015, we investigate the effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt during 50 geomagnetic storms. A statistical study shows that the maximum electron PSDs for various μ (μ = 630, 1096, 2290, and 3311 MeV/G) at L* 4.0 after the storm peak have good correlations with storm intensity (cc 0.70). This suggests that the occurrence and magnitude of geomagnetic storms are necessary for relativistic electron enhancements at the inner edge of the outer radiation belt (L* = 4.0). For moderate or weak storm events (SYM-Hmin > -100 nT) with weak substorm activity (AEmax 0.77). For storm events with intense substorms after the storm peak, relativistic electron enhancements at L* = 4.5 and 5.0 are observed. This shows that intense substorms during the storm recovery phase are crucial to relativistic electron enhancements in the heart of the outer radiation belt. Our statistics study suggests that magnetospheric processes during geomagnetic storms have a significant effect on relativistic electron dynamics.
Beam-front dynamics and ion acceleration in drifting intense relativistic electron beams
International Nuclear Information System (INIS)
Alexander, K.F.; Hintze, W.
1976-01-01
Collective ion acceleration at the injection of a relativistic electron beam into a low-pressure gas or a plasma is discussed and its strong dependence on the beam-front dynamics is shown. A simple one-dimensional model taking explicitly into account the motion and ionizing action of the ions in the beam-front region is developed for the calculation of the beam drift velocity. The obtained pressure dependence is in good agreement with experimental data. The energy distribution is shown of the ions accelerated in the moving potential well of the space charge region. Scaling laws for the beam-front dynamics and ion acceleration are derived. (J.U.)
Burmasov, V. S.; Kandaurov, I. V.; Kruglyakov, E. P.; Meshkov, O. I.
1994-05-01
The traditional way of relativistic electron beam (REB) injection in the experiments on REB- plasma interaction is the injection through an anode foil that separates vacuum diode from plasma chamber. The presence of separating foil leads to the following: (1) replacement of destroyed foil is required after each shot, and (2) the beam angular characteristics making worse. A beam with low angular spread can be obtained from foilless diode placed into strong guiding magnetic field; the problem is how to avoid the diode shortening in the presence of a dense plasma from the interaction chamber. In the experiments on studying of Langmuir turbulence, carrying out on GOL-M device it becomes possible to avoid a separating foil and to obtain a foilless injection of REB into a dense (
Wave-driven butterfly distribution of Van Allen belt relativistic electrons.
Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D N; Spence, H E; Funsten, H O; Blake, J B
2015-10-05
Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day-night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.
Generation of attosecond electron beams in relativistic ionization by short laser pulses
Cajiao Vélez, F.; Kamiński, J. Z.; Krajewska, K.
2018-03-01
Ionization by relativistically intense short laser pulses is studied in the framework of strong-field quantum electrodynamics. Distinctive patterns are found in the energy probability distributions of photoelectrons, which are sensitive to the properties of a driving laser field. It is demonstrated that these electrons are generated in the form of solitary attosecond wave packets. This is particularly important in light of various applications of attosecond electron beams such as in ultrafast electron diffraction and crystallography, or in time-resolved electron microscopy of physical, chemical, and biological processes. We also show that, for intense laser pulses, high-energy ionization takes place in narrow regions surrounding the momentum spiral, the exact form of which is determined by the shape of a driving pulse. The self-intersections of the spiral define the momenta for which the interference patterns in the energy distributions of photoelectrons are observed. Furthermore, these interference regions lead to the synthesis of single-electron wave packets characterized by coherent double-hump structures.
Electron-positron-photon cascades in the strong laser field
Legkov, Maxim; Fedotov, Alexander
2012-06-01
At nearest future several ambitious projects (such as ELI and HiPER) may provide laser filed intensity up to 10^23--10^24 W/cm^2. In such strong fields quantum effects are essential. The most important among them is production of QED cascades. In this paper external field intensity is considered as ultra-relativistic but subcritical. Using a model of two colliding counter-propagating laser beams it was shown that the number of particles during the process is growing exponentially in time. This leads to vast formation of electron-positron-photon plasma. According to numerical simulations, this plasma quickly absorbs an essential part of the energy of the laser field thus leading to its depletion. Numerical simulation has been also performed for a case of high-energetic particle and laser beam collision. Probability rates of direct and recombination processes have been theoretically studied. Under some conditions, recombination may come into play and suppress cascade development. Using approximation of radiation in forward direction, system of kinetic equations, which describes plasma evaluation, was constructed. According to qualitative estimations based on kinetic equations, it was shown that recombination processes can be neglected for optical frequencies range of external field.
Quantum Geometry: Relativistic energy approach to cooperative electron-nucleary-transition spectrum
Directory of Open Access Journals (Sweden)
Ольга Юрьевна Хецелиус
2014-11-01
Full Text Available An advanced relativistic energy approach is presented and applied to calculating parameters of electron-nuclear 7-transition spectra of nucleus in the atom. The intensities of the spectral satellites are defined in the relativistic version of the energy approach (S-matrix formalism, and gauge-invariant quantum-electrodynamical perturbation theory with the Dirac-Kohn-Sham density-functional zeroth approximation.
Tang, C. L.; Wang, Y. X.; Ni, B.; Zhang, J.-C.; Reeves, G. D.; Su, Z. P.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.
2017-05-01
Using the particle data measured by Van Allen Probe A from October 2012 to March 2016, we investigate in detail the radiation belt seed population and its association with the relativistic electron dynamics during 74 geomagnetic storms. The period of the storm recovery phase was limited to 72 h. The statistical study shows that geomagnetic storms and substorms play important roles in the radiation belt seed population (336 keV electrons) dynamics. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of "large flux enhancement" and "small flux enhancement." For large flux enhancement storm events, the correlation coefficients between the peak flux location of the seed population and those of relativistic electrons (592 keV, 1 MeV, 1.8 MeV, and 2.1 MeV) during the storm recovery phase decrease with electron kinetic energy, being 0.92, 0.68, 0.49, and 0.39, respectively. The correlation coefficients between the peak flux of the seed population and those of relativistic electrons are 0.92, 0.81, 0.75, and 0.73. For small flux enhancement storm events, the correlation coefficients between the peak flux location of the seed population and those of relativistic electrons are relatively smaller, while the peak flux of the seed population is well correlated with those of relativistic electrons (correlation coefficients >0.84). It is suggested that during geomagnetic storms there is a good correlation between the seed population and ≤1 MeV electrons and the seed population is important to the relativistic electron dynamics.
Explaining the diverse response of ultra-relativistic Van Allen belt electrons to solar wind forcing
Mann, Ian; Ozeke, Louis; Murphy, Kyle; Claudepierre, Seth; Rae, Jonathan; Milling, David; Kale, Andy; Baker, Daniel
2017-04-01
The NASA Van Allen Probes have opened a new window on the dynamics of ultra-relativistic electrons in the Van Allen radiation belts. Under different solar wind forcing the outer belt is seen to respond in a variety of apparently diverse and sometimes remarkable ways. For example, sometimes a third radiation belt is carved out (e.g., September 2012), or the belts can remain depleted for 10 days or more (September 2014). More usually there is a sequential response of a strong and sometimes rapid depletion followed by a re-energization, the latter increasing outer belt electron flux by orders of magnitude on hour timescales during some of the strongest storms of this solar cycle (e.g., March 2013, March 2015). Such dynamics also appear to be always bounded at low-L by an apparently impenetrable barrier below L 2.8 through which ultra-relativistic electrons do not penetrate. Many studies in the Van Allen Probes era have sought explanations for these apparently diverse features, often incorporating the effects from multiple plasma waves. In contrast, we show how this apparently diverse behaviour can instead be explained by one simple dominant process: ULF wave radial transport. Once ULF wave transport rates are accurately specified by observations, and coupled to the dynamical variation of the outer boundary condition at the edge of the outer belt, the observed diverse responses can all be explained. In order to get good agreement with observations, the modeling reveals the importance of still currently unexplained fast loss in the main phase which decouples pre- and post-storm ultra-relativistic electron flux on hour timescales. Similarly, varying plasmasheet source populations are seen to be of critical importance such that near-tail dynamics likely play a crucial role in Van Allen belt dynamics. Nonetheless, simple models incorporating accurate transport rates derived directly from ULF wave measurements are shown to provide a single natural and compelling explanation
Directory of Open Access Journals (Sweden)
A Parvazian
2010-12-01
Full Text Available Fast ignition is a new method for inertial confinement fusion (ICF in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion (MTF. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0. 25 and 0. 5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. MTF in dual hot spot can be considered as an appropriate substitution for the current ICF techniques.
Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection
Werner, G. R.; Uzdensky, D. A.; Begelman, M. C.; Cerutti, B.; Nalewajko, K.
2018-02-01
Magnetic reconnection in relativistic collisionless plasmas can accelerate particles and power high-energy emission in various astrophysical systems. Whereas most previous studies focused on relativistic reconnection in pair plasmas, less attention has been paid to electron-ion plasma reconnection, expected in black hole accretion flows and relativistic jets. We report a comprehensive particle-in-cell numerical investigation of reconnection in an electron-ion plasma, spanning a wide range of ambient ion magnetizations σi, from the semirelativistic regime (ultrarelativistic electrons but non-relativistic ions, 10-3 ≪ σi ≪ 1) to the fully relativistic regime (both species are ultrarelativistic, σi ≫ 1). We investigate how the reconnection rate, electron and ion plasma flows, electric and magnetic field structures, electron/ion energy partitioning, and non-thermal particle acceleration depend on σi. Our key findings are: (1) the reconnection rate is about 0.1 of the Alfvénic rate across all regimes; (2) electrons can form concentrated moderately relativistic outflows even in the semirelativistic, small-σi regime; (3) while the released magnetic energy is partitioned equally between electrons and ions in the ultrarelativistic limit, the electron energy fraction declines gradually with decreased σi and asymptotes to about 0.25 in the semirelativistic regime; and (4) reconnection leads to efficient non-thermal electron acceleration with a σi-dependent power-law index, p(σ _i)˜eq const+0.7σ _i^{-1/2}. These findings are important for understanding black hole systems and lend support to semirelativistic reconnection models for powering non-thermal emission in blazar jets, offering a natural explanation for the spectral indices observed in these systems.
Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering in Outer RB
Khazanov, G. V.; Gamayunov, K. V.
2007-01-01
We present the equatorial and bounce average pitch angle diffusion coefficients for scattering of relativistic electrons by the H+ mode of EMIC waves. Both the model (prescribed) and self consistent distributions over the wave normal angle are considered. The main results of our calculation can be summarized as follows: First, in comparison with field aligned waves, the intermediate and highly oblique waves reduce the pitch angle range subject to diffusion, and strongly suppress the scattering rate for low energy electrons (E less than 2 MeV). Second, for electron energies greater than 5 MeV, the |n| = 1 resonances operate only in a narrow region at large pitch-angles, and despite their greatest contribution in case of field aligned waves, cannot cause electron diffusion into the loss cone. For those energies, oblique waves at |n| greater than 1 resonances are more effective, extending the range of pitch angle diffusion down to the loss cone boundary, and increasing diffusion at small pitch angles by orders of magnitude.
Compression-amplified EMIC waves and their effects on relativistic electrons
Energy Technology Data Exchange (ETDEWEB)
Li, L. Y., E-mail: lyli-ssri@buaa.edu.cn; Yu, J.; Cao, J. B. [School of Space and Environment, Beihang University, Beijing (China); Yuan, Z. G. [School of Electronic Information, Wuhan University, Wuhan (China)
2016-06-15
During enhancement of solar wind dynamic pressure, we observe the periodic emissions of electromagnetic ion cyclotron (EMIC) waves near the nightside geosynchronous orbit (6.6R{sub E}). In the hydrogen and helium bands, the different polarized EMIC waves have different influences on relativistic electrons (>0.8 MeV). The flux of relativistic electrons is relatively stable if there are only the linearly polarized EMIC waves, but their flux decreases if the left-hand polarized (L-mode) EMIC waves are sufficiently amplified (power spectral density (PSD) ≥ 1 nT{sup 2}/Hz). The larger-amplitude L-mode waves can cause more electron losses. In contrast, the R-mode EMIC waves are very weak (PSD < 1 nT{sup 2}/Hz) during the electron flux dropouts; thus, their influence may be ignored here. During the electron flux dropouts, the relativistic electron precipitation is observed by POES satellite near the foot point (∼850 km) of the wave emission region. The quasi-linear simulation of wave-particle interactions indicates that the L-mode EMIC waves can cause the rapid precipitation loss of relativistic electrons, especially when the initial resonant electrons have a butterfly-like pitch angle distribution.
Influence of Electromagnetic Effects on the Two Stream Instability in a Relativistic Electron Beam,
1984-08-01
as mb = Ybm and me =m, respectively, and the equilibrium axial velocity profile of the beam electrons is independent of r, i.e., Vbz(r) = BbC = const...relativistic mass ratio yj for ions and plasma electrons is unity, mb ybm and E = sgnej. From Eqs. (24) and (25), it is straightforward to show that the
International Nuclear Information System (INIS)
Nasonov, N.; Pokhil, G.; Zhukova, P.
2005-01-01
An emission from relativistic electrons crossing an aligned crystal is considered with account of coherent bremsstrahlung on atomic strings and transition radiation contributions. Some peculiarities in the low energy range of the emission spectrum caused by azimuthal scattering of emitting electrons on atomic strings and an interference between the transition radiation and coherent bremsstrahlung are predicted and analyzed theoretically
International Nuclear Information System (INIS)
Amatuni, A.Ts.; Elbakian, S.S.; Khachatryan, A.G.; Sekhpossian, E.V.
1995-03-01
This document is the final report on a project to study focusing effects of relativistic beams of electrons and positrons interacting with a cold plasma. The authors consider three different models for the overdense cold plasma - electron bunch interaction. They look at coulomb effects, wakefield effects, bunch parameters, and the effects of trains of pulses on focusing properties
All-electron scalar relativistic calculation of water molecule adsorption onto small gold clusters.
Kuang, Xiang-Jun; Wang, Xin-Qiang; Liu, Gao-Bin
2011-08-01
An all-electron scalar relativistic calculation was performed on Au( n )H(2)O (n = 1-13) clusters using density functional theory (DFT) with the generalized gradient approximation at PW91 level. The calculation results reveal that, after adsorption, the small gold cluster would like to bond with oxygen and the H(2)O molecule prefers to occupy the single fold coordination site. Reflecting the strong scalar relativistic effect, Au( n ) geometries are distorted slightly but still maintain a planar structure. The Au-Au bond is strengthened and the H-O bond is weakened, as manifested by the shortening of the Au-Au bond-length and the lengthening of the H-O bond-length. The H-O-H bond angle becomes slightly larger. The enhancement of reactivity of the H(2)O molecule is obvious. The Au-O bond-lengths, adsorption energies, VIPs, HLGs, HOMO (LUMO) energy levels, charge transfers and the highest vibrational frequencies of the Au-O mode for Au( n )H(2)O clusters exhibit an obvious odd-even oscillation. The most favorable adsorption between small gold clusters and the H(2)O molecule takes place when the H(2)O molecule is adsorbed onto an even-numbered Au( n ) cluster and becomes an Au( n )H(2)O cluster with an even number of valence electrons. The odd-even alteration of magnetic moments is observed in Au( n )H(2)O clusters and may serve as material with a tunable code capacity of "0" and "1" by adsorbing a H(2)O molecule onto an odd or even-numbered small gold cluster.
International Nuclear Information System (INIS)
López, Rodrigo A.; Muñoz, Víctor; Viñas, Adolfo F.; Valdivia, Juan A.
2015-01-01
We use a particle-in-cell simulation to study the propagation of localized structures in a magnetized electron-positron plasma with relativistic finite temperature. We use as initial condition for the simulation an envelope soliton solution of the nonlinear Schrödinger equation, derived from the relativistic two fluid equations in the strongly magnetized limit. This envelope soliton turns out not to be a stable solution for the simulation and splits in two localized structures propagating in opposite directions. However, these two localized structures exhibit a soliton-like behavior, as they keep their profile after they collide with each other due to the periodic boundary conditions. We also observe the formation of localized structures in the evolution of a spatially uniform circularly polarized Alfvén wave. In both cases, the localized structures propagate with an amplitude independent velocity
Single electron attachment and stripping cross sections for relativistic heavy ions
International Nuclear Information System (INIS)
Crawford, H.J.
1979-06-01
The results of a Bevalac experiment to measure the single electron attachment and stripping cross sections for relativistic (0.5 1 , and fully stripped, N 0 , ion beams emerging from the targets. Separate counters measured the number of ions in each charge state. The ratios N 1 /N 0 for different target thicknesses were fit to a simple growth curve to yield electron attachment and stripping cross sections. The data are compared to relativistic extrapolations of available theories. Clear evidence for two separate attachment processes, radiative and non-radiative, is found. Data are compared to a recently improved formulation for the stripping cross sections
Single electron attachment and stripping cross sections for relativistic heavy ions
International Nuclear Information System (INIS)
Crawford, H.J.
1979-01-01
The results of a Bevalac experiment to measure the single electron attachment and stripping cross sections for relativistic (0.5 1 , and fully stripped, N 0 , ion beams emerging from the targets. Separate counters measured the number of ions in each charge state. The ratios N 1 /N 0 for different target thicknesses were fit to a simple growth curve to yield electron attachment and stripping cross sections. The data are compared to relativistic extrapolations of available theories. Clear evidence of two separate attachment processes, radiative and non-radiative, is found. Data are compared to a recently improved formulation for the stripping cross sections
Free electron laser with bunched relativistic electron beam and electrostatic longitudinal wiggler
International Nuclear Information System (INIS)
Sepehri Javan, Nasser
2010-01-01
The system of the nonlinear nonstationary equations describing spatial-temporal dynamics of the amplitudes of an undulator radiation and a space charge wave of a relativistic electron beam in the resonator is obtained. The electrostatic longitudinal wiggler is considered. A bunch of the electron beam injects to the resonator, at the ends of which two mirrors are placed. After the interaction of electrons of bunch with radiation in the presence of wiggler and after amplifying electromagnetic pulse, a part of radiation is reflected back by semitransparent mirror. Then, it reaches to the initial of the system where the other mirror is placed. Synchronously, when the pulse is reflecting, the other electron bunch enters to the resonator and interacts with the pulse. This operation has simulated until saturation of growth of the electromagnetic pulse. The dynamics of the problem is simulated by the method of macro particles. The dynamics of pulse amplification, motion of the electrons, and spectra of output radiation in each stage are simulated.
Turner, D. L.; O'Brien, T. P.; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Jaynes, A. N.; Baker, D. N.; Kanekal, S.; Gkioulidou, M.; Henderson, M. G.; Reeves, G. D.
2017-01-01
Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can exceed 3 orders of magnitude in the slot region and continues into the inner radiation belt, which is evidence that these events are an important—and potentially dominant—source of inner belt electrons. Electron fluxes from September 2012 through February 2016 reveal that SPELLS occur frequently ( 2.5/month at 200 keV), but the number of observed events decreases exponentially with increasing electron energy for ≥100 keV. After SPELLS events, the slot region reforms due to slow energy-dependent decay over several day time scales, consistent with losses due to interactions with plasmaspheric hiss. Combined, these results indicate that the peaked phase space density distributions in the inner electron radiation belt result from an "on/off," geomagnetic-activity-dependent source from higher radial distances.
Kiefer, D.; Yeung, M.; Dzelzainis, T.; Foster, P.S.; Rykovanov, S.G.; Lewis, C.LS.; Marjoribanks, R.S.; Ruhl, H.; Habs, D.; Schreiber, J.; Zepf, M.; Dromey, B.
2013-01-01
Reflecting light from a mirror moving close to the speed of light has been envisioned as a route towards producing bright X-ray pulses since Einstein’s seminal work on special relativity. For an ideal relativistic mirror, the peak power of the reflected radiation can substantially exceed that of the incident radiation due to the increase in photon energy and accompanying temporal compression. Here we demonstrate for the first time that dense relativistic electron mirrors can be created from the interaction of a high-intensity laser pulse with a freestanding, nanometre-scale thin foil. The mirror structures are shown to shift the frequency of a counter-propagating laser pulse coherently from the infrared to the extreme ultraviolet with an efficiency >104 times higher than in the case of incoherent scattering. Our results elucidate the reflection process of laser-generated electron mirrors and give clear guidance for future developments of a relativistic mirror structure. PMID:23612304
International Nuclear Information System (INIS)
Peter, W.; Faehl, R.J.
1983-01-01
A new concept for a small compact multimegajoule energy storage device utilizing relativistically densified electron beam circulating in a torus is presented. The electron cloud is produced through inductive charge injection by a travelling magnetic wave circulating the torus. Parameters are given for two representative toroidal energy storage devices, consisting of 1 m and 32 m in radius respectively, which could store more than 4 x 10 17 electrons and 30' MJ in energy. The concept utilizes the idea that large electric and magnetic fields can be produced by a partially space-charge neutralized intense relativistic electron beam which could become many orders of magnitude greater than the externally applied field confining the beam. In the present approach, the electron cloud densification can be achieved gradually by permitting multiple traversals of the magnetic wave around the torus. The magnetic mirror force acts on the orbital magnetic electron dipole moment and completely penetrates the entire electron cloud. As the electrons gain relativistic energies, the beam can be continuously densified at the front of the travelling wave, where the magnetic field is rising with time. The use of travelling magnetic wave to accelerate an electron cloud and the use of large electric field at the thusly accelerated cloud form the basis for a high beam intensity and hence high energy storage. Technical considerations and several potential applications, which include the driving of a powerful gyrotron, are discussed
Moya, Pablo S.; Pinto, Víctor A.; Sibeck, David G.; Kanekal, Shrikanth G.; Baker, Daniel N.
2017-11-01
Using Van Allen Probes Energetic Particle, Composition, and Thermal Plasma-Relativistic Electron-Proton Telescope (ECT-REPT) observations, we performed a statistical study on the effect of geomagnetic storms on relativistic electrons fluxes in the outer radiation belt for 78 storms between September 2012 and June 2016. We found that the probability of enhancement, depletion, and no change in flux values depends strongly on L and energy. Enhancement events are more common for ˜2 MeV electrons at L ˜ 5, and the number of enhancement events decreases with increasing energy at any given L shell. However, considering the percentage of occurrence of each kind of event, enhancements are more probable at higher energies, and the probability of enhancement tends to increases with increasing L shell. Depletion are more probable for 4-5 MeV electrons at the heart of the outer radiation belt, and no-change events are more frequent at L 4.5 the probability of enhancement, depletion, or no-change response presents little variation for all energies. Because these probabilities remain relatively constant as a function of radial distance in the outer radiation belt, measurements obtained at geosynchronous orbit may be used as a proxy to monitor E≥1.8 MeV electrons in the outer belt.
RELATIVISTIC ELECTRON SHOCK DRIFT ACCELERATION IN LOW MACH NUMBER GALAXY CLUSTER SHOCKS
International Nuclear Information System (INIS)
Matsukiyo, S.; Ohira, Y.; Yamazaki, R.; Umeda, T.
2011-01-01
An extreme case of electron shock drift acceleration (SDA) in low Mach number collisionless shocks is investigated as a plausible mechanism for the initial acceleration of relativistic electrons in large-scale shocks in galaxy clusters, where the upstream plasma temperature is of the order of 10 keV and the degree of magnetization is not too small. One-dimensional electromagnetic full particle simulations reveal that, even when a shock is rather moderate, a part of the thermal incoming electrons are accelerated and reflected through relativistic SDA and form a local non-thermal population just upstream of the shock. The accelerated electrons can self-generate local coherent waves and further be back-scattered toward the shock by those waves. This may be a scenario for the first stage of the electron shock acceleration occurring at the large-scale shocks in galaxy clusters, such as CIZA J2242.8+5301, which have well-defined radio relics.
The detection of ultra-relativistic electrons in low Earth orbit
Katsiyannis, Athanassios C.; Dominique, Marie; Pierrard, Viviane; Rosson, Graciela Lopez; Keyser, Johan De; Berghmans, David; Kruglanski, Michel; Dammasch, Ingolf E.; Donder, Erwin De
2018-01-01
Aims: To better understand the radiation environment in low Earth orbit (LEO), the analysis of in-situ observations of a variety of particles, at different atmospheric heights, and in a wide range of energies, is needed. Methods: We present an analysis of energetic particles, indirectly detected by the large yield radiometer (LYRA) instrument on board ESA's project for on-board autonomy 2 (PROBA2) satellite as background signal. Combining energetic particle telescope (EPT) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV. Results: The observed events are strongly correlated to geo-magnetic activity and appear even during modest disturbances. They are also well confined geographically within the L = 4-6 McIlwain zone, which makes it possible to identify their source. Conclusions: Although highly energetic particles are commonly perturbing data acquisition of space instruments, we show in this work that ultra-relativistic electrons with energies in the range of 2-8 MeV are detected only at high latitudes, while not present in the South Atlantic Anomaly region.
Czech Academy of Sciences Publication Activity Database
Hajra, R.; Tsurutani, B. T.; Echer, E.; Gonzalez, W. D.; Brum, Ch. G. M.; Antunes Vieira, L. E.; Santolík, Ondřej
2015-01-01
Roč. 67, Article Number 109 (2015), 109/1-109/11 ISSN 1880-5981 R&D Projects: GA MŠk LH12231 Institutional support: RVO:68378289 Keywords : HILDCAAs * high-speed streams * CIRs * chorus plasma waves * radiation belt * magnetospheric relativistic electrons * solar wind * geomagnetic storms Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.871, year: 2015
Plasma heating in a long solenoid by a laser or a relativistic electron beam
International Nuclear Information System (INIS)
Tajima, T.
1975-01-01
Advances in the technology of a large energy laser and/or relativistic electron beam (REB) generator have made it possible to seriously consider a long solenoid reactor concept. This concept has been reviewed. The physical problems in the plasma heating of the long solenoid by a laser or a REB are studied
Time-dependent field equations for paraxial relativistic electron beams: Beam Research Program
International Nuclear Information System (INIS)
Sharp, W.M.; Yu, S.S.; Lee, E.P.
1987-01-01
A simplified set of field equations for a paraxial relativistic electron beam is presented. These equations for the beam electrostatic potential phi and pinch potential Phi identical to A/sub z/ - phi retain previously neglected time-dependent terms and for axisymmetric beams reduce exactly to Maxwell's equations
Relativistic electron beam source with an air-core step-up transformer
International Nuclear Information System (INIS)
Mohri, Akihiro; Ikuta, Kazunari; Masuzaki, Masaru; Tsuzuki, Tetsuya; Fujiwaka, Setsuya.
1975-04-01
An air-core step-up transformer with a high coupling factor has been developed to generate a high voltage pulse for charging the pulse forming line of a relativistic electron beam source. A beam source using the transformer was constructed and well operated for the beam injection into a toroidal system. (auth.)
Radial focusing of a relativistic electron beam in a bipotential electrostatic lens
International Nuclear Information System (INIS)
Genoni, T.C.
1994-01-01
The focusing of a relativistic electron beam in a bipotential electrostatic lens is discussed. An iterative scheme for the solution of the paraxial ray equation is used to derive approximate analytic formulas for the lens parameters and lens transfer matrix elements. The formulas are compared to results of direct numerical integration of the paraxial ray equation
The EMP excitation of radiation by the pulsed relativistic electron beam
International Nuclear Information System (INIS)
Balakirev, V.A.; Sidelnikov, G.L.
1996-01-01
The mechanisms of excitation of ultra-wideband electromagnetic pulses (EMP) by short pulses of high-current relativistic electron beams were proposed and investigated. It is shown that the transformation efficiency of the bunch kinetic energy to the excited energy of the EMP can be very significant. (author). 2 figs., 4 refs
Loss of the relativistic and ultra-relativistic radiation belt electrons
Shprits, Yuri; Drozdov, Alexander; Kellerman, Adam; Usanova, Maria; Aseev, Nikita; Spasovevich, Maria
2017-04-01
Recent observations and modeling provided significant improvements in our understanding of the energization mechanisms for the electrons in the radiation belts. However, loss processes remain poorly understood. In this study we present analysis of the evolution of electron radial profiles of fluxes, pitch angle and energy distributions. Our modeling and observational results show that different loss mechanisms are operational at different energies. Global simulations at all energies, radial distances, and pitch angels are compared to Van Allen Probes observations of electron fluxes. VERB 3D model including various waves is capable of reproducing the dynamics of pitch angle distributions and energy spectra, demonstrating which loss mechanisms dominate at different energies. Analysis of the profiles of phase space density provides additional confirmation for our conclusion and presents a novel technique that identifies the region of intense local loss due to EMIC wave scattering.
Strong coupling operation of a free-electron-laser amplifier with an axial magnetic field
Energy Technology Data Exchange (ETDEWEB)
Rullier, J.L.; Devin, A.; Gardelle, J.; Labrouche, J.; Le Taillandier, P. [Commissariat a lEnergie Atomique, Boite Postale 2, 33114 Le Barp (France); Donohue, J.T. [Centre dEtudes Nucleaires de Bordeaux-Gradignan, Boite Postale 120, 33175 Gradignan (France)
1996-03-01
We present the results of a free-electron-laser (FEL) experiment at 35 GHz, using a strongly relativistic electron beam ({ital T}=1.75 MeV). The electron pulse length is 30 ns full width at half maximum with a peak current of 400 A. The FEL is designed to operate in the high-gain Compton regime, with a negative coupling parameter ({Phi}{lt}0) leading to a strong growth rate. More than 50 MW of rf power in the TE{sub 1}{sub 1} mode (43 dB gain) has been obtained with good reproducibility. The experimental results are in good agreement with predictions made using the three-dimensional stationary simulation code solitude. {copyright} {ital 1996 The American Physical Society.}
Fluorescence excited in a thunderstorm atmosphere by relativistic runaway electron avalanches
Babich, L. P.; Bochkov, E. I.
2017-05-01
The spectrum and spatiotemporal evolution of the fluorescence of an atmospheric discharge developing in the regime of relativistic runaway electron avalanche (RREA) generation have been calculated without involving the relativistic feedback. The discharges generating narrow bipolar pulses, along with the discharges responsible for terrestrial gamma-ray flashes, are shown to be relatively dark. Nevertheless, the fluorescence excited by a discharge involving RREAs can be recorded with cameras used to record high-altitude optical phenomena. A possible connection between a certain class of optical phenomena observed at the tops of thunderclouds and RREA emission is pointed out.
Energy spectrum of Compton scattering of laser photons on relativistic electrons
International Nuclear Information System (INIS)
Ando, Hiroaki; Yoneda, Yasuharu
1976-01-01
The high energy photons in gamma-ray region are obtainable by the Compton scattering of laser photons on relativistic electrons. But the motion of the electrons in the storage ring is not necessarily uniform. In the study of the uneven effect, the energy distribution of scattered photons is derived from the assumed momentum distribution of incident electrons. It is generally impossible to derive the momentum distribution of incident electrons from the energy spectrum of scattered photons. The additional conditions which make this possible in a special case are considered. A calculational method is examined for deriving the energy spectrum of scattered photons from the assumed momentum distribution of incident electrons. (Mori, K.)
CURRENT SHEET REGULATION OF SOLAR NEAR-RELATIVISTIC ELECTRON INJECTION HISTORIES
Energy Technology Data Exchange (ETDEWEB)
Agueda, N.; Sanahuja, B. [Departament d' Astronomia i Meteorologia, Institut de Ciencies del Cosmos, Universitat de Barcelona (Spain); Vainio, R. [Department of Physics, University of Helsinki (Finland); Dalla, S. [Jeremiah Horrocks Institute, University of Central Lancashire (United Kingdom); Lario, D. [Applied Physics Laboratory, Johns Hopkins University (United States)
2013-03-10
We present a sample of three large near-relativistic (>50 keV) electron events observed in 2001 by both the ACE and the Ulysses spacecraft, when Ulysses was at high-northern latitudes (>60 Degree-Sign ) and close to 2 AU. Despite the large latitudinal distance between the two spacecraft, electrons injected near the Sun reached both heliospheric locations. All three events were associated with large solar flares, strong decametric type II radio bursts and accompanied by wide (>212 Degree-Sign ) and fast (>1400 km s{sup -1}) coronal mass ejections (CMEs). We use advanced interplanetary transport simulations and make use of the directional intensities observed in situ by the spacecraft to infer the electron injection profile close to the Sun and the interplanetary transport conditions at both low and high latitudes. For the three selected events, we find similar interplanetary transport conditions at different heliolatitudes for a given event, with values of the mean free path ranging from 0.04 AU to 0.27 AU. We find differences in the injection profiles inferred for each spacecraft. We investigate the role that sector boundaries of the heliospheric current sheet (HCS) have on determining the characteristics of the electron injection profiles. Extended injection profiles, associated with coronal shocks, are found if the magnetic footpoints of the spacecraft lay in the same magnetic sector as the associated flare, while intermittent sparse injection episodes appear when the spacecraft footpoints are in the opposite sector or a wrap in the HCS bounded the CME structure.
Relativistic electrons of the outer radiation belt and methods of their forecast (review
Directory of Open Access Journals (Sweden)
Potapov A.S.
2017-03-01
Full Text Available The paper reviews studies of the dynamics of relativistic electrons in the geosynchronous region. It lists the physical processes that lead to the acceleration of electrons filling the outer radiation belt. As one of the space weather factors, high-energy electron fluxes pose a serious threat to the operation of satellite equipment in one of the most populated orbital regions. Necessity is emphasized for efforts to develop methods for forecasting the situation in this part of the magnetosphere, possible predictors are listed, and their classification is given. An example of a predictive model for forecasting relativistic electron flux with a 1–2-day lead time is proposed. Some questions of practical organization of prediction are discussed; the main objectives of short-term, medium-term, and long-term forecasts are listed.
Relativistic nature of carriers: Origin of electron-hole conduction asymmetry in monolayer graphene
Srivastava, Pawan Kumar; Arya, Swasti; Kumar, Santosh; Ghosh, Subhasis
2017-12-01
We report electron-hole conduction asymmetry in monolayer graphene. Previously, it has been claimed that electron-hole conduction asymmetry is due to imbalanced carrier injection from metallic electrodes. Here, we show that metallic contacts have negligible impact on asymmetric conduction and may be either sample or device-dependent phenomena. Electrical measurements show that monolayer graphene based devices exhibit suppressed electron conduction compared to hole conduction due to the presence of donor impurities which scatter electrons more efficiently. This can be explained by the relativistic nature of charge carriers in a graphene monolayer and can be reconciled with the fact that in a relativistic quantum system transport cross section does depend on the sign of scattering potential in contrast to a nonrelativistic quantum system.
International Nuclear Information System (INIS)
Friedman, M.
1989-01-01
This final Progress Report addresses DOE-sponsored research on the development of future high-gradient particle accelerators. The experimental and the theoretical research, which lasted three years, investigated the Two Beam Accelerator (TBA). This high-voltage-gradient accelerator was powered by a modulated intense relativistic electron beam (MIREB) of power >10 10 watts. This research was conceived after a series of successful experiments performed at NRL generating and using MIREBs. This work showed that an RF structure could be built which was directly powered by a modulated intense relativistic electron beam. This structure was then used to accelerate a second electron beam. At the end of the three year project the proof-of-principle accelerator demonstrated the generation of a high current beam of electrons with energy >60 MeV. Scaling laws needed to design practical devices for future applications were also derived
Project: Modeling Relativistic Electrons from Nuclear Explosions in the Magnetosphere
Energy Technology Data Exchange (ETDEWEB)
Cowee, Misa [Los Alamos National Laboratory; Gary, S. Peter [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Liu, Kaijun [Los Alamos National Laboratory
2012-07-17
We present a summary of the FY12 activities for DTRA-funded project 'Modeling Relativistic Electrons from Nuclear Explosions in the Magnetosphere'. We briefly review the outstanding scientific questions and discuss the work done in the last year to try to answer these questions. We then discuss the agenda for this Technical Meeting with the DTRA sponsors. In the last year, we have continued our efforts to understand artificial radiation belts from several different perspectives: (1) Continued development of Electron Source Model (ESM) and comparison to HANE test data; (2) Continued studies of relativistic electron scattering by waves in the natural radiation belts; (3) Began study of self-generated waves from the HANE electrons; and (4) Began modeling for the UCLA laser experiment.
Solitary waves in dusty plasmas with weak relativistic effects in electrons and ions
Energy Technology Data Exchange (ETDEWEB)
Kalita, B. C., E-mail: bckalita123@gmail.com [Gauhati University, Department of Mathematics (India); Choudhury, M., E-mail: choudhurymamani@gmail.com [Handique Girls’ College, Department of Mathematics (India)
2016-10-15
Two distinct classes of dust ion acoustic (DIA) solitary waves based on relativistic ions and electrons, dust charge Z{sub d} and ion-to-dust mass ratio Q’ = m{sub i}/m{sub d} are established in this model of multicomponent plasmas. At the increase of mass ratio Q’ due to increase of relativistic ion mass and accumulation of more negative dust charges into the plasma causing decrease of dust mass, relativistic DIA solitons of negative potentials are abundantly observed. Of course, relativistic compressive DIA solitons are also found to exist simultaneously. Further, the decrease of temperature inherent in the speed of light c causes the nonlinear term to be more active that increases the amplitude of the rarefactive solitons and dampens the growth of compressive solitons for relatively low and high mass ratio Q’, respectively. The impact of higher initial streaming of the massive ions is observed to identify the point of maximum dust density N{sub d} to yield rarefactive relativistic solitons of maximum amplitude.
Cao, Xing; Shprits, Yuri Y; Ni, Binbin; Zhelavskaya, Irina S
2017-12-18
Electron flux in the Earth's outer radiation belt is highly variable due to a delicate balance between competing acceleration and loss processes. It has been long recognized that Electromagnetic Ion Cyclotron (EMIC) waves may play a crucial role in the loss of radiation belt electrons. Previous theoretical studies proposed that EMIC waves may account for the loss of the relativistic electron population. However, recent observations showed that while EMIC waves are responsible for the significant loss of ultra-relativistic electrons, the relativistic electron population is almost unaffected. In this study, we provide a theoretical explanation for this discrepancy between previous theoretical studies and recent observations. We demonstrate that EMIC waves mainly contribute to the loss of ultra-relativistic electrons. This study significantly improves the current understanding of the electron dynamics in the Earth's radiation belt and also can help us understand the radiation environments of the exoplanets and outer planets.
International Nuclear Information System (INIS)
Bekefi, G.; Shefer, R.E.
1979-01-01
Generation of submillimeter radiation by stimulated Raman scattering in an intense relativistic electron beam subjected to a spatially periodic transverse electric field is examined. The requisite electric field modulation can be obtained by rippling the wall of the conducting drift tube. When the electron beam is subjected to a periodic longitudinal electric field, short-wavelength plasmons, rather than photons, are generated. The growth rate and other parameters related to this instability are discussed
Wave-driven butterfly distribution of Van Allen belt relativistic electrons
Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.
2015-01-01
Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon h...
Pair production with electron capture in peripheral collisions of relativistic heavy ions
Energy Technology Data Exchange (ETDEWEB)
Bertulani, C.A.C.A. E-mail: bertu@if.ufrj.br; Dolci, D.D. E-mail: dolci@if.ufrj.br
2001-02-26
The production of electron-positron pairs with the capture of the electron in an atomic orbital is investigated for the conditions of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Dirac wave functions for the leptons are used, taking corrections to orders of Z{alpha} into account. The dependence on the transverse momentum transfer is studied and the accuracy of the equivalent photon approximation is discussed as a function of the nuclear charge.
X-Ray Imaging of Ultrafast Magnetic Reconnection Driven by Relativistic Electrons
Raymond, Anthony; McKelvey, Andrew; Zulick, Calvin; Maksimchuk, Anatoly; Thomas, Alexander; Willingale, Louise; Chvykov, Vladimir; Yanovsky, Victor; Krushelnick, Karl
2014-10-01
Magnetic reconnection events driven by relativistic electrons are observed between two high intensity laser/plasma interaction sites. The two laser focuses were on average 20 μm FWHM containing 50 TW of power each, delivered with a split f/3 paraboloid onto copper foil targets at a focused intensity of 4×1018 W/cm2. A spherically bent k-alpha X-ray Bragg crystal was utilized to image the interactions, and by motorizing one half of the paraboloid vertically the focal separation was varied between 0-200 μm. While these k-alpha images demonstrated a ring structure surrounding a single focus (due to electrons returning from vacuum to the rear of the target surface), splitting the focuses revealed the rings of either spot interacting and enhancing between the focuses, evidencing magnetic reconnection driven by the relativistic electron currents. Imaging the transversely propagating electrons with a filtered LANEX screen demonstrated relativistic currents with spatial nonuniformities potentially directly originating from reconnection events, and varying target geometries were used to investigate the resulting effects on the spatial electron profiles. At present PIC simulations are being conducted to better understand and attempt to reproduce the measured electron outflow dynamics. Currently at: ELI Attosecond Light Pulse Source.
International Nuclear Information System (INIS)
Nation, J.A.
1992-01-01
This report describes work carried out on DOE contract number DE-AC02-80ER10569 during the period December 15, 1979 to May 31, 1992. The original purpose of this research was to investigate the use of slow space charge waves on weakly relativistic electron beams for ion acceleration. The work had three major objectives: development of a suitable ion injector, growth and study of the properties of slow space charge waves on an electron beam, and a combination of the two components into a suitable proof-of-principle demonstration of the wave accelerator. Work focused on the first two of these objectives. Control of the space charge waves' phase velocity was not obtained to the degree required for a working accelerator, so the project was duly terminated in favor of a program which focused on generating ultra high power microwave signals suitable for use in the next linear collider. Work done to develop suitable efficient, inexpensive, phase-stable microwave sources, with peak powers of up to 1 GW in the X band in pulses shorter than 1 ns, is described. Included are lists of the journal and conference papers resulting from this work, as well as a list of graduate students who completed their Ph.D. studies on the projects described in this report
Energy Technology Data Exchange (ETDEWEB)
Hack, Szabolcs [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged (Hungary); Varró, Sándor [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Wigner Research Center for Physics, SZFI, PO Box 49, H-1525 Budapest (Hungary); Czirják, Attila [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged (Hungary)
2016-02-15
We investigate nonlinear Thomson scattering as a source of high-order harmonic radiation with the potential to enable attosecond light pulse generation. We present a new analytic solution of the electron’s relativistic equations of motion in the case of a short laser pulse with a sine-squared envelope. Based on the single electron emission, we compute and analyze the radiated amplitude and phase spectrum for a realistic electron bunch, with special attention to the correct initial values. These results show that the radiation spectrum of an electron bunch in head-on collision with a sufficiently strong laser pulse of sine-squared envelope has a smooth frequency dependence to allow for the synthesis of attosecond light pulses.
International Nuclear Information System (INIS)
Hack, Szabolcs; Varró, Sándor; Czirják, Attila
2016-01-01
We investigate nonlinear Thomson scattering as a source of high-order harmonic radiation with the potential to enable attosecond light pulse generation. We present a new analytic solution of the electron’s relativistic equations of motion in the case of a short laser pulse with a sine-squared envelope. Based on the single electron emission, we compute and analyze the radiated amplitude and phase spectrum for a realistic electron bunch, with special attention to the correct initial values. These results show that the radiation spectrum of an electron bunch in head-on collision with a sufficiently strong laser pulse of sine-squared envelope has a smooth frequency dependence to allow for the synthesis of attosecond light pulses.
Electron Dynamics in Nanostructures in Strong Laser Fields
Energy Technology Data Exchange (ETDEWEB)
Kling, Matthias
2014-09-11
The goal of our research was to gain deeper insight into the collective electron dynamics in nanosystems in strong, ultrashort laser fields. The laser field strengths will be strong enough to extract and accelerate electrons from the nanoparticles and to transiently modify the materials electronic properties. We aimed to observe, with sub-cycle resolution reaching the attosecond time domain, how collective electronic excitations in nanoparticles are formed, how the strong field influences the optical and electrical properties of the nanomaterial, and how the excitations in the presence of strong fields decay.
Novel aspects of direct laser acceleration of relativistic electrons
Arefiev, Alexey
2015-11-01
Production of energetic electrons is a keystone aspect of ultraintense laser-plasma interactions that underpins a variety of topics and applications, including fast ignition inertial confinement fusion and compact particle and radiation sources. There is a wide range of electron acceleration regimes that depend on the duration of the laser pulse and the plasma density. This talk focuses on the regime in which the plasma is significantly underdense and the laser pulse duration is longer than the electron response time, so that, in contrast to the wakefield acceleration regime, the pulse creates a quasi-static channel in the electron density. Such a regime is of particular interest, since it can naturally arise in experiments with solid density targets where the pre-pulse of an ultraintense laser produces an extended sub-critical pre-plasma. This talk examines the impact of several key factors on electron acceleration by the laser pulse and the resulting electron energy gain. A detailed consideration is given to the role played by: (1) the static longitudinal electric field, (2) the static transverse electric field, (3) the electron injection into the laser pulse, (4) the electromagnetic dispersion, and (5) the static longitudinal magnetic field. It is shown that all of these factors lead, under conditions outlined in the talk, to a considerable electron energy gain that greatly exceeds the ponderomotive limit. The static fields do not directly transfer substantial energy to electrons. Instead, they alter the longitudinal dephasing between the electrons and the laser pulse, which then allows the electrons to gain extra energy from the pulse. The talk will also outline a time-resolution criterion that must be satisfied in order to correctly reproduce these effects in particle-in-cell simulations. Supported by AFOSR Contract No. FA9550-14-1-0045, National Nuclear Security Administration Contract No. DE-FC52-08NA28512, and US Department of Energy Contract No. DE-FG02
The Work Function Associated with Ultra-relativistic Electron ...
Indian Academy of Sciences (India)
the study of anisotropic nature of work function in the presence of strong quantizing magnetic field, relevant for strongly magnetized neutron star crustal region, has not been studied earlier. Of course, a completely different approach, popularly known as density functional theory (DFT) has been used by Medin & Lai (2006, ...
Single-electrode monitors for relativistic intense electron beam parameters
International Nuclear Information System (INIS)
Stratienko, V.A.; Khorenko, V.K.
1977-01-01
A single-electrode monitor operating in atmosphere on delta-electrons for precision measurement of high-intensity electron beams is developed. As an emitter is used a 0.2 mm aluminium foil with a hole which is a replica of the sample subjected to radiation. The electric charge from the emitter is recorded by a current integrator. The single-electrode monitor enabled to form a 225 MeV electron beam with a flux density of 5x10 15 electrons/ (cm 2 and confine the latter for 140 hours with an accuracy of +- 0.2 mm. Controlling the beam shifting by means of the single-electrode monitor described, it is possible to measure the real dimensions and density distributions of high-intensity electron beams
Quasilinear analysis of loss-cone driven weakly relativistic electron cyclotron maser instability
International Nuclear Information System (INIS)
Ziebell, L.F.; Yoon, P.H.
1995-01-01
This paper presents a quasilinear analysis of the relativistic electron cyclotron maser instability. Two electron populations are assumed: a low-temperature background component and a more energetic loss-cone population. The dispersion relation is valid for any ratio of the energetic to cold populations, and includes thermal and relativistic effects. The quasilinear analysis is based upon an efficient kinetic moment method, in which various moment equations are derived from the particle kinetic equation. A model time-dependent loss-cone electron distribution function is assumed, which allows one to evaluate the instantaneous linear growth rate as well as the moment kinetic equations. These moment equations along with the wave kinetic equation form a fully self-consistent set of equations which governs the evolution of the particles as well as unstable waves. This set of equations is solved with physical parameters typical of the earth's auroral zone plasma. copyright 1995 American Institute of Physics
Thermal sensitive paper as a diagnostic for intense relativistic electron beam dynamics
Energy Technology Data Exchange (ETDEWEB)
Gilgenbach, R.M.; McDermott, D.B.; Marshall, T.C.
1978-08-01
Thermal sensitive paper has been used as a diagnostic for an intense relativistic electron beam propagating in a rippled magnetic field. The E/sub r/ x B/sub z/ rotation of the beam has been measured from the exposed pattern on the thermal paper and used to calculate the electrostatic field of the beam E/sub r/, and the corresponding values of electron density and beam current. Exposed strips of thermal paper show longitudinal modulation of the radial electron velocity with a period corresponding to that of a rippled magnetic field; modulation of the radial electron velocity at the cyclotron frequency has also been observed.
Liu, Si; Yan, Qi; Yang, Chang; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Gao, Zhonglei; Xiao, Fuliang
2018-02-01
Previous studies have revealed a typical picture that seed electrons are transported inward under the drive of radial diffusion and then accelerated via chorus to relativistic energies. Here we show a potentially different process during the 2-3 October 2013 storm when Van Allen Probes observed extremely rapid (by about 50 times in 2 h) flux enhancements of relativistic (1.8-3.4 MeV) electrons but without distinct chorus at lower L-shells. Meanwhile, Time History of Events and Macroscale Interactions during Substorms satellites simultaneously measured enhanced chorus and fluxes of energetic (˜100-300 keV) seed electrons at higher L-shells. Numerical calculations show that chorus can efficiently accelerate seed electrons at L ˜ 8.3. Then radial diffusion further increased the phase space density of relativistic electrons throughout the outer radiation belts, with a remarkable agreement with the observation in magnitude and timescale. The current results provide a different physical scenario on the interplay between radial diffusion and local acceleration in outer radiation belt.
Min, Sun-Hong; Kwon, Ohjoon; Sattorov, Matlabjon; Baek, In-Keun; Kim, Seontae; Hong, Dongpyo; Jeong, Jin-Young; Jang, Jungmin; Bera, Anirban; Barik, Ranjan Kumar; Bhattacharya, Ranajoy; Cho, Ilsung; Kim, Byungsu; Park, Chawon; Jung, Wongyun; Park, Seunghyuk; Park, Gun-Sik
2018-02-01
When a semiconductor element is irradiated with radiation in the form of a transient pulse emitted from a nuclear explosion, a large amount of charge is generated in a short time in the device. A photocurrent amplified in a certain direction by these types of charges cause the device to break down and malfunction or in extreme cases causes them to burn out. In this study, a pulse-type γ-ray generator based on a relativistic electron beam accelerator (γ=2.2, β=0.89) which functions by means of tungsten impingement was constructed and tested in an effort to investigate the process and effects of the photocurrent formed by electron hole pairs (EHP) generated in a pMOSFET device when a transient radiation pulse is incident in the device. The pulse-type γ-ray irradiating device used here to generate the electron beam current in a short time was devised to allow an increase in the irradiation dose. A precise signal processing circuit was constructed to measure the photocurrent of the small signal generated by the pMOSFET due to the electron beam accelerator pulse signal from the large noise stemming from the electromagnetic field around the relativistic electron beam accelerator. The pulse-type γ-ray generator was installed to meet the requirements of relativistic electron beam accelerators, and beam irradiation was conducted after a beam commissioning step.
Dynamic of non relativistic electrons and protons in the plasmasphere
International Nuclear Information System (INIS)
Mendes Junior, O.; Pinto Junior, O.; Gonzalez, W.D.
1985-01-01
A study of the dynamics of electrons and protons inside the plasmasphere is presented. These particles are subjected to the geomagnetic field and to plasmaspheric electric fields, given by simple static models, during magnetically quiet and disturbed periods. (author) [pt
Study of relativistic electron beams generated by a foilless diode
International Nuclear Information System (INIS)
Jones, M.E.; Thode, L.E.
1979-01-01
Preliminary results of a numerical and analytical study of foilless diodes are presented. The work produced an electron emission algorithm for the particle-in-cell simulation code CCUBE. Diode performance was studied as a function of applied magnetic field strength and simple geometry changes. Annular electron beams with an energy of 5 MeV appear obtainable with densities exceeding 10 14 cm -3 . 8 figures
Directory of Open Access Journals (Sweden)
Xueying Lu
2015-08-01
Full Text Available We present the design of a volumetric metamaterial (MTM structure and its interaction with a relativistic electron beam. This novel structure has promising applications in particle beam diagnostics, acceleration, and microwave generation. The volumetric MTM has a cubic unit cell allowing structures of arbitrary size to be configured as an array of identical cells. This structure allows the exploration of the properties of a metamaterial structure without having to consider substrates or other supporting elements. The dispersion characteristics of the unit cell are obtained using eigenmode simulations in the hfss code and also using an effective medium theory with spatial dispersion. Good agreement is obtained between these two approaches. The lowest-order mode of the MTM structure is found to have a negative group velocity in all directions of propagation. The frequency spectrum of the radiation from a relativistic electron beam passing through the MTM structure is calculated analytically and also calculated with the cst code, with very good agreement. The radiation pattern from the relativistic electron beam is found to be backward Cherenkov radiation, which is a promising tool for particle diagnostics. Calculations are also presented for the application of a MTM-based wakefield accelerator as a possible all-metal replacement for the conventional dielectric wakefield structure. The proposed structure may also be useful for MTM-based vacuum electron devices for microwave generation and amplification.
Transport of a relativistic electron beam through hydrogen gas
International Nuclear Information System (INIS)
Haan, P. de.
1981-01-01
In this thesis the author describes the transport properties of an electron beam through vacuum and through hydrogen gas with pressure ranging from 25 to 1000 Pa. Maximum beam energy and current are 0.8 MeV and 6 kA, respectively. The pulse length is around 150 ns. A description is given of the experimental device. Also the diagnostics for probing the beam and the plasma, produced by the beam, are discussed, as well as the data acquisition system. The interaction between the beam and hydrogen gas with a pressure around 200 Pa is considered. A plasma with density around 10 19 m -3 is produced within a few nanoseconds. Measurements yield the atomic hydrogen temperature, electron density, beam energy loss, and induced plasma current and these are compared with the results of a model combining gas ionization and dissociation, and turbulent plasma heating. The angular distribution of the beam electrons about the magnetic field axis is discussed. (Auth.)
Imaging nanometer-scale beamlets arrays of relativistic electron beams
Energy Technology Data Exchange (ETDEWEB)
Li, R. K.; To, H.; Musumeci, P. [Department of Physics and Astronomy, UCLA, Los Angeles, California, 90095 (United States)
2012-12-21
In this paper we study the evolution of nanometer scale transverse density modulation of a high brightness electron beam through a drift and simple focusing channel. With the help of particle tracking simulations we analyze the effects of space charge forces, emittance and energy spread on the feasibility of recovering an initial nm-scale transverse modulation after transport through a magnifying optical system. These studies are relevant for applications such as time-resolved MeV transmission electron microscopy and in the high brightness electron beam community due to the recent developments of nano-structured cathodes and due to the possibility of taking advantage of nm-structures in the beam for coherent radiation generation.
Momentum spectra for single and double electron ionization of He in relativistic collisions
International Nuclear Information System (INIS)
Wood, C.J.; Olson, R.E.
1997-08-01
The complete momentum spectra for single and double ionization of He by 1GeV/u (β=0.88) U 92+ have been investigated using a classical trajectory Monte Carlo method corrected for the relativistic projectile. The 1/r 12 electron-electron interaction has been included in the post-collision region for double ionization to incorporate the effects of both the nuclear-electron and electron-electron ionizing interactions, and to access the effects of electron correlation in the electron spectra. Experimental measurements were able to determine the longitudinal momentum spectra for single ionization; these observations are in accordance with the theoretical predictions for the three-body momentum balance between projectile, recoil ion, and ionized electron. In particular, the Lorentz contraction of the Coulomb interaction of the projectile manifests itself in the decrease of the post-collision interaction of the projectile with the electron and recoil ion, causing them to recoil back-to-back as in the case for a short electromagnetic pulse. This feature is clearly displayed in both the theoretical and experimental longitudinal momentum spectra, and by comparing to calculations that are performed at the same collision speed but do not include the relativistic potentials. Moreover, collision plane spectra of the three particles demonstrate that the momenta of the recoil ion and ionized electron are preferentially equal, and opposite, to each other. The electron spectra for double ionization show that the inclusion of the electron-electron interaction in the post-collision regime partitions the combined ionization momentum of the electrons so that the electrons are preferentially emitted in opposite azimuthal angles to one another. This is in contrast to calculations made assuming independent electrons. (orig.)
Energy Dependence of Near-relativistic Electron Spectrum at ...
Indian Academy of Sciences (India)
Abstract. In view of the renewed interest in the study of energetic par- ticles in the outer radiation belt of the earth, we feel it will be helpful in looking for the energy dependence of the electron energy spectrum at geo- stationary orbit. This may give us some insight into how we can safeguard geostationary satellites from ...
Relativistic effects on the modulational instability of electron plasma ...
Indian Academy of Sciences (India)
2Centre for Science Education and Research, P-1 B.P. Township, Kolkata 700 094, India. ∗. Corresponding author. E-mail: bsdvghosh@gmail.com. MS received 24 August 2011; revised .... tic electron plasma waves in classical plasma. The group dispersion effect is found to increase sharply with wavenumber k in the low-k ...
Formation and dynamics of electrostatic solitary waves associated with relativistic electron beam
Moslem, W. M.; Bencheriet, F.; Sabry, R.; Djebli, M.
2012-04-01
Properties of nonlinear electrostatic solitary waves in a plasma are analyzed by using the hydrodynamic model for electrons, positrons, and relativistic electron beam. For this purpose, the Kadomtsev-Petviashvili (KP) equation has been derived and its analytical solution is presented. It is found that the nonlinear solitary structures can propagate as slow and fast modes. The dependence of these modes on the plasma parameters is defined numerically. Furthermore, positive and negative electrostatic solitary structures can exist. In order to show that the characteristics of the solitary wave profile are influenced by the plasma parameters, the relevant numerical analysis of the KP equation is obtained. The electrostatic solitary waves, as predicted here, may be associated with the nonlinear structures caused by the interaction of relativistic jets with plasma medium, such as in the active galactic nuclei and in the magnetosphere of collapsing stars.
Interaction of relativistic short proton bunches with space charge limited electron clouds
Directory of Open Access Journals (Sweden)
F. B. Petrov
2014-12-01
Full Text Available The electron cloud buildup and interaction with a train of relativistic, short proton bunches is studied using particle-in-cell codes. The simulation models describe the electron generation at the beam pipe wall as well as the wakefield behind the bunches. The study focuses on the space charge limited (saturated cloud profile between the bunches and on the incoherent tune spread caused by the interaction of the saturated cloud with individual bunches. Analytical expressions describing the pinch of a saturated electron cloud are derived and compared to simulation results.
Interaction of relativistic electrons with plasma facing components
International Nuclear Information System (INIS)
Bartels, H.W.
1992-07-01
Runaway electrons can cause severe damage to plasma facing components of large tokamaks. The designs proposed for the first wall and divertor of the next large fusion experiment, ITER (International Thermonuclear Experimental Reactor), are investigated. Energies of up to 300 MeV per electron and surface energy depositions of 30 MJ/m 2 are assumed. The GEANT code originating from high energy physics was used to model the energy deposition [J/cm 3 ] quantitatively as a function of the penetration depth and material. A two dimensional representation of the geometry was chosen. For the third coordinate the assumption of symmetric conditions is very close to reality. The magnetic field was included in the analysis. It causes bending back of reflected charged particles and reduced penetration depth of the electrons due to the gyration of the electrons around the magnetic field lines. The energy deposition in the bulk material for a given surface energy load is roughly independent of the incident angle and energy (above 100 MeV) since the main physical process of the energy loss is the formation of an electromagnetic shower, i.e. rapid dissipation of the initial energy into many electrons, positrons and photons. Typical divertor designs protect the cooling tubes with a 1 cm thick graphite layer. Melting of such molybdenum (copper) cooling tubes occurs at a heat load of 50 (25) MJ/m 2 . Every additional cm of graphite roughly doubles the runaway protection. Since it is proposed to operate ITER with low cooling water temperatures (T H2O 2 . (orig.)
Observations of collective ion acceleration by a relativistic electron beam in a magnetic cusp
International Nuclear Information System (INIS)
Roberson, C.W.; Eckhouse, S.; Fisher, A.; Robertson, S.; Rostoker, N.
1976-01-01
Ion pulses of 10 13 protons were observed by passing hollow relativistic electron beams through a magnetic cusp using drift-chamber fill pressures from 75 to 600 mTorr of H 2 . Magnetic fields of 0.8 kG suppress the mechanism responsible for acceleration without magnetic field. A different mechanism appears to begin and peak as the cusp threshold is approached. More than 10 11 protons with energies greater than 2 MeV were observed
Planar channeled relativistic electrons and positrons in the field of resonant hypersonic wave
International Nuclear Information System (INIS)
Grigoryan, L.Sh.; Mkrtchyan, A.H.; Khachatryan, H.F.; Tonoyan, V.U.; Wagner, W.
2003-01-01
The wave function of a planar channeled relativistic particle (electron, positron) in a single crystal excited by longitudinal hypersonic vibrations (HVs) is determined. The obtained expression is valid for periodic (not necessarily harmonic) HV of desired profile and single crystals with an arbitrary periodic continuous potential. A revised formula for the wave number of HV that exert resonance influence on the state of a channeled particle was deduced to allow for non-linear effects due to the influence of HV
Precipitation of Trapped Relativistic Electrons by Amplified Whistler Waves in the Magnetosphere
2007-06-01
From - To) 27-06-2007 1 REPRINT I 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Precipitation of trapped relativistic electrons by amplified whistler waves...in the magnetosphere 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62101F 6. AUTHORS 5d. PROJECT NUMBER S.P. Kuo*, Steven S. Kuo**, James T. Huynh...Airborne Systems, El Segundo, CA 90245 14. ABSTRACT Numerical study of a loss-cone negative mass instability to amplify whistler waves by energewtic
Stabilization of the arrival time of a relativistic electron beam to the 50 fs level
Roberts, J.; Skowronski, P.; Burrows, P. N.; Christian, G. B.; Corsini, R.; Ghigo, A.; Marcellini, F.; Perry, C.
2018-01-01
We report the results of a low-latency beam phase feed-forward system built to stabilize the arrival time of a relativistic electron beam. The system was operated at the Compact Linear Collider (CLIC) Test Facility (CTF3) at CERN where the beam arrival time was stabilized to approximately 50 fs. The system latency was 350 ns and the correction bandwidth >23 MHz . The system meets the requirements for CLIC.
Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons
Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q.-G.; Zhou, X.-Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y.-X.; Gao, Zhonglei; He, Zhaoguo; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.
2015-01-01
Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance ha...
On the new belt of relativistic electrons at L=1.9 according to Meteor data
International Nuclear Information System (INIS)
Ginzburg, E.A.; Malyshev, A.B.; Pustosvetov, V.P.
1993-01-01
On the base of regular observations of energetic particle fluxes by means of the 'Meteor' satellite apparatus is found the new phenomenon - the narrow belt of trapped relativistic electrons with the maximum at L=1.8-1.9. Continuous observations permit to obtain elaborate information on the features of the belt spatial structure, its dynamics and energy spectra with the moment of its generation 24.3.1991
Simulation of ultra-relativistic electrons and positrons channeling in crystals with MBN Explorer
DEFF Research Database (Denmark)
Sushko, Gennady B.; Bezchastnov, Victor G.; Solov'yov, Ilia
2013-01-01
A newly developed code, implemented as a part of the MBN Explorer package (Solov'yov et al., 2012; http://www.mbnexplorer.com/, 2012) [1] and [2] to simulate trajectories of an ultra-relativistic projectile in a crystalline medium, is presented. The motion of a projectile is treated classically b......=855 MeV electrons and positrons in oriented Si(110) crystal and in amorphous silicon....
An assessment of relativistic electron beam for plasma heating in magnetically confined devices
International Nuclear Information System (INIS)
Paithankar, A.S.; Rohatgi, V.K.
1979-01-01
The status and progress of various techniques employed for heating the plasma to thermonuclear temperature in magnetically confined devices are presented. The merits and demerits of each technique are critically studied with a view to assess the potential of Relativistic Electron Beam (REB) heating technique, which is a new comer in the field. It has been concluded that REB heating is very much suitable for linear solenoidal reactor devices and is also a potential future candidate for plasma heating for torodial devices. (auth.)
Energy Technology Data Exchange (ETDEWEB)
Kemp, Gregory Elijah [The Ohio State Univ., Columbus, OH (United States)
2013-01-01
Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic
Relativistic electron transport and bremsstrahlung production in solar flares
Miller, James A.; Ramaty, Reuven
1989-01-01
A Monte Carlo simulation of ultrarelativistic electron transport in solar flare magnetic loops has been developed. It includes Coulomb, synchrotron, and bremsstrahlung energy losses; pitch-angle scattering by Alfven and whistler turbulence in the coronal region of the loop; and magnetic mirroring in the converging magnetic flux tubes beneath the transition region. Depth distributions, time profiles, energy spectra, and angular distributions of the resulting bremsstrahlung emission are calculated. It is found that both the preferential detection of solar flares with greater than 10 MeV emission near the limb of the sun and the observation of ultrarelativistic electron bremsstrahlung from flares on the disk are consequences of the loop transport model. The declining portions of the observed time profiles of greater than 10 MeV emission from solar flares can also be accounted for, and it is proposed that these portions are determined by transport and not acceleration.
Transition radiation from relativistic electrons in periodic radiators
Cherry, M. L.; Mueller, D.; Prince, T. A.; Hartmann, G.
1974-01-01
The generation and detection of transition radiation have been studied in a series of experiments with electrons from 1 to 15 GeV at SLAC and at the Cornell Synchrotron. Periodic radiators, consisting of thin plastic foils stretched in air at constant spacings, were used, and proportional chambers filled with krypton or xenon served as detectors. A detailed discussion of the theoretical predictions is given, and the measurements are systematically compared with the predictions by varying the most critical parameters, such as configuration of radiators and detectors, and energy of the electrons. In general, good agreement between theory and experiment has been found. On the basis of these results, the criteria are summarized under which transition radiation can readily be observed.
First observation of Smith-Purcell radiation from relativistic electrons
International Nuclear Information System (INIS)
Doucas, G.; Mulvey, J.H.; Omori, M.; Walsh, J.; Kimmitt, M.F.
1992-01-01
A beam of 3.6 MeV electrons has been used to study the generation of radiation in far infra-red (FIR) by the Smith-Purcell mechanism. The dependence of wavelength on angle of emission, over angles from 56 deg to 150 deg and wavelengths from 350 μm to 1860 μm, is in excellent agreement with the Smith-Purcell dispersion relation. Comparison of the yield with that from a 5000 K source suggests that the spontaneous Smith-Purcell effect offers an easily tunable alternative to the synchrotron as a coherent FIR source, and could form the basis of a cheap, compact Free Electron Laser (FEL). (author) 6 refs.; 5 figs
Current density monitor for intense relativistic electron beams
International Nuclear Information System (INIS)
Fiorito, R.B.; Raleigh, M.; Seltzer, S.M.
1986-01-01
We describe a new type of electric probe which is capable of measuring the time-resolved current density profile of a stable, reproducible, high-energy (>4-MeV) high-current (>1-kA) electron beam. The sensing element of this probe is an open-ended but capped-off 50-Ω coaxial line constructed of graphite. The graphite sensor is 4.3 mm in diameter, 6 cm long, and is range thin to the primary beam electrons. The probe produces a signal proportional to the intercepted beam current. When the sensor is scanned radially through the beam during repeated pulses, a curve of signal versus depth of insertion is produced from which the radial current density profile can be determined. Measurements are presented of the profile of the electron beam from the Experimental Test Accelerator (4.5 MeV, 10 kA) at Lawrence Livermore National Laboratory. Good agreement is shown between measurements made with this probe and the beam radius as predicted by transport codes. The advantage of the electric probe lies in its ruggedness, simplicity, inherent fast rise time, and low cost. In contrast to other systems it requires no radiation shielding, water cooling, or auxiliary support equipment to operate in an intense beam environment
Drozdov, Alexander; Shprits, Yuri; Kellerman, Adam; Usanova, Maria; Aseev, Nikita; Baker, Daniel; Spence, Harlan; Reeves, Geoff
2016-04-01
In this study, we compare long-term simulations performed by the Versatile Electron Radiation Belt (VERB) code with the Van Allen Probes observations. The model takes into account radial, energy, pitch-angle and mixed diffusion, losses into the atmosphere, and magnetopause shadowing. We include scattering by hiss and chorus based on a recently developed statistical models of VLF/ELF waves obtained from EMFISIS instrument. We consider the energetic (>100 KeV), relativistic (~0.5-1 MeV) and ultra-relativistic (>2 MeV) electrons. One year of relativistic electron measurements are well reproduced by the simulation during a period of the various geomagnetic activity. However, for ultra-relativistic energies, the VERB code simulation significantly overestimates electron phase space density. Since the additional loss is required only at very high energies we conclude that EMIC waves is the most likely additional source of scattering that could explain observed decay rates.
Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zheng, Huinan; Shen, Chao; Wang, Yuming; Wang, Shui
2013-06-01
Electromagnetic ion cyclotron (EMIC) waves are long suggested to account for the rapid loss of radiation belt relativistic electrons. Here we perform both theoretical analysis and numerical simulation to comprehensively investigate the nonlinear interaction between EMIC wave and relativistic electrons. In particular, we emphasize the dependence of nonlinear processes on the electron initial latitude. The nonlinear phase trapping yields negative equatorial pitch angle transport, with efficiency varying over the electron initial latitude, implying that it can increase the loss rate predicted by quasilinear theory. The nonlinear channel effect phase bunching produces positive equatorial pitch angle transport, less dependent on the electron initial latitude, suggesting that it can decrease the loss rate predicted by quasilinear theory. The nonlinear cluster effect phase bunching alternately causes positive and negative equatorial pitch angle transport, quasi-periodically dependent on the electron initial latitude, suggesting that it can either decrease or increase the loss rate predicted by the quasilinear theory. Such latitudinal dependence of nonlinear processes should be taken into account in the evaluation of radiation belt electron loss rate driven by EMIC waves.
Fullekrug, Martin; Hanuise, C; Parrot, M
2011-01-01
Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables an experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which...
Wave-Particle Interactions on Relativistic Electron Beams.
1980-05-16
block nuebstj C-, S_ i l iN .... . .6l I~A.S i~In V )d... D D 1473 EDO ,o,, OF 1 NOv i IS 02SOLTE . S/NC 007-014-CL601 , -T ASIeStC4-UIrYl CLAS’.IFICA...differential equation and per- nits the electron orbits to turn in the wave frame, corresponding as one advances along the beam in the direction of...state helical orbits are included. If perturbed, these orbits oscillate about equilibrium, so that substantial gain enhancement can occur if the
Relativistically strong CO{sub 2} laser driver for plasma-channeled particle acceleration
Energy Technology Data Exchange (ETDEWEB)
Pogorelsky, I.V.
1995-12-31
Long-wavelength, short-duration laser pulses are desirable for plasma wakefield particle acceleration and plasma waveguiding. The first picosecond terawatt CO{sub 2} laser is under development to test laser-driven electron acceleration schemes.
Dielectric laser acceleration of non-relativistic electrons at a photonic structure
Energy Technology Data Exchange (ETDEWEB)
Breuer, John
2013-08-29
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28 keV electrons. We measure a maximum energy gain of 280 eV, corresponding to an acceleration gradient of 25 MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100 nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in
Dielectric laser acceleration of non-relativistic electrons at a photonic structure
International Nuclear Information System (INIS)
Breuer, John
2013-01-01
This thesis reports on the observation of dielectric laser acceleration of non-relativistic electrons via the inverse Smith-Purcell effect in the optical regime. Evanescent modes in the vicinity of a periodic grating structure can travel at the same velocity as the electrons along the grating surface. A longitudinal electric field component is used to continuously impart momentum onto the electrons. This is only possible in the near-field of a suitable photonic structure, which means that the electron beam has to pass the structure within about one wavelength. In our experiment we exploit the third spatial harmonic of a single fused silica grating excited by laser pulses derived from a Titanium:sapphire oscillator and accelerate non-relativistic 28 keV electrons. We measure a maximum energy gain of 280 eV, corresponding to an acceleration gradient of 25 MeV/m, already comparable with state-of-the-art radio-frequency linear accelerators. To experience this acceleration gradient the electrons approach the grating closer than 100 nm. We present the theory behind grating-based particle acceleration and discuss simulation results of dielectric laser acceleration in the near-field of photonic grating structures, which is excited by near-infrared laser light. Our measurements show excellent agreement with our simulation results and therefore confirm the direct acceleration with the light field. We further discuss the acceleration inside double grating structures, dephasing effects of non-relativistic electrons as well as the space charge effect, which can limit the attainable peak currents of these novel accelerator structures. The photonic structures described in this work can be readily concatenated and therefore represent a scalable realization of dielectric laser acceleration. Furthermore, our structures are directly compatible with the microstructures used for the acceleration of relativistic electrons demonstrated in parallel to this work by our collaborators in
Simulation of relativistically colliding laser-generated electron flows
Czech Academy of Sciences Publication Activity Database
Yang, X.B.; Dieckmann, M.E.; Sarri, G.; Borghesi, Marco
Roč. 19, č. 11 ( 2012 ), "113110-1"-"113110-7" ISSN 1070-664X R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OPVK 3 Laser Zdroj(XE) CZ.1.07/2.3.00/20.0279 Program:EE Institutional research plan: CEZ:AV0Z10100523 Keywords : laser-plasma interaction * laser generated electron flows * simulation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.376, year: 2012 http://pop.aip.org/resource/1/phpaen/v19/i11/p113110_s1?isAuthorized=no
STATISTICAL STUDY ON THE DECAY PHASE OF SOLAR NEAR-RELATIVISTIC ELECTRON EVENTS
International Nuclear Information System (INIS)
Lario, D.
2010-01-01
We study the decay phase of solar near-relativistic (53-315 keV) electron events as observed by the Advanced Composition Explorer (ACE) and the Ulysses spacecraft during solar cycle 23. By fitting an exponential function (exp - t/τ) to the time-intensity profile in the late phase of selected solar near-relativistic electron events, we examine the dependence of τ on electron energy, electron intensity spectra, event peak intensity, event fluence, and solar wind velocity, as well as heliocentric radial distance, heliolatitude, and heliolongitude of the spacecraft with respect to the parent solar event. The decay rates are found to be either independent or slightly decrease with the electron energy. No clear dependence is found between τ and the heliolongitude of the parent solar event, with the exception of well-connected events for which low values of τ are more commonly observed than for poorly-connected events. For those events concurrently observed by ACE and Ulysses, decay rates increase at distances >3 AU. Events with similar decay rates at ACE and Ulysses were observed mainly when Ulysses was at high heliographic latitudes. We discuss the basic physical mechanisms that control the decay phase of the electron events and conclude that both solar wind convection and adiabatic deceleration effects influence the final shape of the decay phase of solar energetic particle events, but not as expressed by the models based on diffusive transport acting on an isotropic particle population.
Breneman, A. W.; Crew, A.; Sample, J.; Klumpar, D.; Johnson, A.; Agapitov, O.; Shumko, M.; Turner, D. L.; Santolik, O.; Wygant, J. R.; Cattell, C. A.; Thaller, S.; Blake, B.; Spence, H.; Kletzing, C. A.
2017-11-01
We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT the low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 and MLT = 10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus waves with durations and cadences similar to the microbursts. No other waves were observed. This is the first time that chorus and microbursts have been simultaneously observed with a separation smaller than a chorus packet. A majority of the microbursts do not have the energy dispersion expected for trapped electrons bouncing between mirror points. This confirms that the electrons are rapidly (nonlinearly) scattered into the loss cone by a coherent interaction with the large amplitude (up to ˜900 pT) chorus. Comparison of observed time-averaged microburst flux and estimated total electron drift shell content at L = 5.6 indicate that microbursts may represent a significant source of energetic electron loss in the outer radiation belt.
International Nuclear Information System (INIS)
Popa, Alexandru
2009-01-01
In a previous paper we presented a calculation model for high harmonic generation by relativistic Thomson scattering of the electromagnetic radiation by free electrons. In this paper we present a similar model for the calculation of the energies of hard x-rays (20- 200 keV) resulted from the interaction between relativistic electrons (20-100 MeV) and very intense laser beams. Starting from the relativistic equations of motion of an electron in the electromagnetic field we show that the Lienard-Wiechert equation leads to electromagnetic waves whose frequencies are in the domain of hard x-rays. When the relativistic parameter of the laser beam is greater than unity, the model predicts the existence of harmonics of the above frequencies. Our theoretical values are in good agreement with experimental values of the x-ray energies from the literature and predict accurately their angular distribution.
Directory of Open Access Journals (Sweden)
Maruyama Tomoyuki
2016-01-01
Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum approach do not agree with those obtained in the semi-classical approach. Then, we find that the anomalous magnetic moment of the proton greatly enhances the production rate by about two orders magnitude, and that the decay width satisfies a robust scaling law.
Directory of Open Access Journals (Sweden)
Maruyama Tomoyuki
2016-01-01
Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum-field approach do not agree with those obtained in the semi-classical approach. Furthermore, we also find that the anomalous magnetic moment of the proton greatly enhances the production rate about by two orders of magnitude, and that the polar angle of an emitted pion is the same as that of an initial proton.
Total yield of channeling radiation from relativistic electrons in thin Si and W crystals
International Nuclear Information System (INIS)
Abdrashitov, S.V.; Bogdanov, O.V.; Dabagov, S.B.; Pivovarov, Yu.L.; Tukhfatullin, T.A.
2013-01-01
Orientation dependences of channeling radiation total yield from relativistic 155–855 MeV electrons at both 〈1 0 0〉 axial and (1 0 0) planar channeling in thin silicon and tungsten crystals are studied by means of computer simulations. The model as well as computer code developed allows getting the quantitative results for orientation dependence of channeling radiation that can be used for crystal alignment in channeling experiments and/or for diagnostics of initial angular divergence of electron beam
One-electron atomic-molecular ions containing lithium in a strong magnetic field
International Nuclear Information System (INIS)
Olivares-Pilon, H; Turbiner, A V; Vieyra, J C Lopez; Baye, D
2010-01-01
The one-electron lithium-containing Coulomb systems of atomic type Li 2+ and molecular type Li 5+ 2 , LiHe 4+ and LiH 3+ are studied in the presence of a strong magnetic field B ≤ 10 7 au in a non-relativistic framework. They are considered at the Born-Oppenheimer approximation of zero order (infinitely massive centres) within the parallel configuration (molecular axis parallel to the magnetic field). The variational and Lagrange-mesh methods are employed, complementing each other. It is demonstrated that the molecular systems LiH 3+ , LiHe 4+ and Li 5+ 2 can exist for sufficiently strong magnetic fields B ∼> 10 4 au and that Li 5+ 2 can even be stable at magnetic fields typical of magnetars.
International Nuclear Information System (INIS)
Martinolli, E.
2003-04-01
This work is dedicated to the study of the energy deposition of fast electrons in matter. This topic is of prime importance for inertial fusion driven by laser since relativistic electrons are produced in laser-matter interaction for a laser operating in ultra-intense regime. This thesis is made up of: a theoretical chapter dealing with the generation and transport of fast electrons, of 2 chapters reporting experimental data obtained with optical and X-rays diagnostics at the laser facilities of LULI in France and RAL in U.K., and of a chapter dedicated to the simulation of electron transport by using a Monte-Carlo code combined to a hybrid collisional-electromagnetic PIC code. A new spectrometer has been designed: the detection of Kα rays coming from a fluorescent layer embedded in the target has allowed us to assess the size of the electron beam and the level of ionisation. (A.C.)
Relativistic electrons in the outer-zone: An 11 year cycle, their relation to the solar wind
Energy Technology Data Exchange (ETDEWEB)
Belian, R.D.; Cayton, T.E.; Christensen, R.A.; Ingraham, J.C.; Meier, M.M.; Reeves, G.D. [Los Alamos National Lab., NM (United States); Lazarus, A.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States)
1994-12-31
We examine Los Alamos energetic electron data from 1979 through the present to show long term trends in the trapped relativistic electron populations at geosynchronous-earth-orbit (GEO). Data is examined from several CPA and SOPA instruments to cover the interval from 1979 through June 1994. It is shown that the higher energy electrons fluxes (E > 300 keV) displayed a cycle of {approx}11 years. In agreement with other investigators, we also show that the relativistic electron cycle is out of phase with the sunspot cycle. We compare the occurrences of relativistic electrons and solar wind high speed streams and determine that on the time scale of 15 years the two do not correlate well. The long-term data set we provide here shows a systematic change of the electron energy spectrum during the course of the solar cycle. This information should be useful to magnetospheric scientists, model designers and space flight planners.
Long-term relativistic radiation belt electron responses to GEM magnetic storms
Kim, Kyung-Chan; Shprits, Yuri
2013-08-01
We present a long-term radiation belt simulation for a 200-day period starting on 25 January 1991, which includes both six geomagnetic storms identified by the Geospace Environment Modeling (GEM) focus group and non-stormy periods of the Combined Release and Radiation Effects Satellite (CRRES) mission, using 3-D time-dependent Versatile Electron Radiation Belt (VERB) code, and compare the simulation results with a multisatellite phase space density (PSD) reanalysis obtained using Kalman filtering of observations from CRRES, GEO, GPS, and Akebono satellites, as well as with the CRRES MEA 1 MeV electron observation. The processes accounted for in the model are radial diffusion-driven by ultra-low frequency (ULF) electromagnetic fluctuations and local (pitch-angle and energy) scattering by plasmaspheric hiss and chorus waves, respectively, inside and outside the plasmasphere. The observations show that a significant decrease in the relativistic electrons in the outer radiation belt is observed in association with the solar wind dynamic pressure enhancement during the main phase of each storm, while during the recovery phase, different types of relativistic electron flux profiles are identified: increased, decreased, and unchanged relative to the pre-storm flux level. First, for an increase of relativistic electrons relative to the pre-storm flux level, the comparison of simulation with reanalysis shows that inward radial diffusion and local acceleration coupled with each other result in a net acceleration. Second, for a decrease or lack of change in relativistic electrons, competing effects of pitch-angle scattering, outward diffusion, and acceleration produce the net decrease in electron PSD and fluxes. The results show that the overall time evolution of the radiation belt is in good agreement with our model simulations, indicating that modeling, including radial diffusion and pitch-angle scattering, is reasonable in predicting the general long-term structure of the
Koch, J A; Key, M H; Freeman, R R; Hatchett, S P; Lee, R W; Pennington, D; Stephens, R B; Tabak, M
2002-01-01
In our experiments, we irradiated solid CH targets with a 400 J, 5 ps, 3 x 10(19) W/cm(2) laser, and we used x-ray imaging and spectroscopic diagnostics to monitor the keV x-ray emission from thin Al or Au tracer layers buried within the targets. The experiments were designed to quantify the spatial distribution of the thermal electron temperature and density as a function of buried layer depth; these data provide insights into the behavior of relativistic electron currents which flow within the solid target and are directly and indirectly responsible for the heating. We measured approximately 200-350 eV temperatures and near-solid densities at depths ranging from 5 to 100 microm beneath the target surface. Time-resolved x-ray spectra from Al tracers indicate that the tracers emit thermal x rays and cool slowly compared to the time scale of the laser pulse. Most intriguingly, we consistently observe annular x-ray images in all buried tracer-layer experiments, and these data show that the temperature distribution is columnar, with enhanced heating along the edges of the column. The ring diameters are much greater than the laser focal spot diameter and do not vary significantly with the depth of the tracer layer for depths greater than 30 microm. The local temperatures are 200-350 eV for all tracer depths. We discuss recent simulations of the evolution of electron currents deep within solid targets irradiated by ultra-high-intensity lasers, and we discuss how modeling and analytical results suggest that the annular patterns we observe may be related to locally strong growth of the Weibel instability. We also suggest avenues for future research in order to further illuminate the complex physics of relativistic electron transport and energy deposition inside ultra-high-intensity laser-irradiated solid targets.
Particle Production in Strong Electromagnetic Fields in Relativistic Heavy-Ion Collisions
Directory of Open Access Journals (Sweden)
Kirill Tuchin
2013-01-01
Full Text Available I review the origin and properties of electromagnetic fields produced in heavy-ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches ~mπ2 at RHIC and ~10mπ2 at LHC. I demonstrate by explicit analytical calculation that after dropping by about one-two orders of magnitude during the first fm/c of plasma expansion, it freezes out and lasts for as long as quark-gluon plasma lives as a consequence of finite electrical conductivity of the plasma. Magnetic field breaks spherical symmetry in the direction perpendicular to the reaction plane, and therefore all kinetic coefficients are anisotropic. I examine viscosity of QGP and show that magnetic field induces azimuthal anisotropy on plasma flow even in spherically symmetric geometry. Very strong electromagnetic field has an important impact on particle production. I discuss the problem of energy loss and polarization of fast fermions due to synchrotron radiation, consider photon decay induced by magnetic field, elucidate J/ψ dissociation via Lorentz ionization mechanism, and examine electromagnetic radiation by plasma. I conclude that all processes in QGP are affected by strong electromagnetic field and call for experimental investigation.
Kalita, B. C.; Deka, M.
2013-02-01
In the two component relativistic plasmas subject to pressure variation of adiabatic electrons and isothermal ions, both compressive and rarefactive KdV solitons are established in a quite different physical plasma model. It is desirable to define c s in a new way to substantiate the validity of the model under relativistic effects. The corresponding mathematical condition is also determined, which is a new report of this kind. It is also interesting to report that the relativistic rarefactive solitons cease to exist below some critical ion initial streaming speed v i0 for a fixed temperature α and electron streaming speed v e0. Besides, higher initial flux v i0 of ions under constant temperature is observed to generate higher speed v i at the passage of time which causes to increase (in relativistic sense) its mass diminishing thereby the growth of soliton amplitudes.
International Nuclear Information System (INIS)
Mahmood, S.; Sadiq, Safeer; Haque, Q.
2013-01-01
Linear and nonlinear electrostatic waves in magnetized dense electron-ion plasmas are studied with nonrelativistic and ultra-relativistic degenerate and singly, doubly charged helium (He + , He ++ ) and hydrogen (H + ) ions, respectively. The dispersion relation of electrostatic waves in magnetized dense plasmas is obtained under both the energy limits of degenerate electrons. Using reductive perturbation method, the Zakharov-Kuznetsov equation for nonlinear propagation of electrostatic solitons in magnetized dense plasmas is derived for both nonrelativistic and ultra-relativistic degenerate electrons. It is found that variations in plasma density, magnetic field intensity, different mass, and charge number of ions play significant role in the formation of electrostatic solitons in magnetized dense plasmas. The numerical plots are also presented for illustration using the parameters of dense astrophysical plasma situations such as white dwarfs and neutron stars exist in the literature. The present investigation is important for understanding the electrostatic waves propagation in the outer periphery of compact stars which mostly consists of hydrogen and helium ions with degenerate electrons in dense magnetized plasmas
particle simulation for electrostatic oscillation of virtual cathode in relativistic electron beams
International Nuclear Information System (INIS)
Chen Deming; Wang Min
1990-01-01
The virtual cathode oscillation in relativistic electron beams is studied by a 1-D electrostatic particle simulation code with finite-size-particle model. When injection current is less than the space charge limiting current, electron beam propagates stably and transsmits completely. When injection current exceeds the space charge limit, its propagation is unstable, a part of electrons reflect and the other electrons transsmit. The position and potential of the virtual cathode caused by space charge effects oscillate periodically. When the beam current increases, the virtual cathode position closer to the injection plane and its oscillating region gets narrower, the virtual cathode potential decreases and its amplitude increases, the oscillation frequency increases above the beam plasma frequency
MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation
Ivanov, I. A.; Arzhannikov, A. V.; Burdakov, A. V.; Burmasov, V. S.; Gavrilenko, D. E.; Kasatov, A. A.; Kandaurov, I. V.; Kurkuchekov, V. V.; Kuznetsov, S. A.; Mekler, K. I.; Polosatkin, S. V.; Popov, S. S.; Postupaev, V. V.; Rovenskikh, A. F.; Sklyarov, V. F.; Sorokina, N. V.; Trunev, Yu. A.; Vyacheslavov, L. N.
2015-12-01
There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70-110 keV for the electron energy, 1-10 MW for the beam power and 30-300 μs for its duration. The spectrum was measured in 75-230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.
MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation
Energy Technology Data Exchange (ETDEWEB)
Ivanov, I. A., E-mail: Ivanov@inp.nsk.su; Arzhannikov, A. V.; Burmasov, V. S.; Popov, S. S.; Postupaev, V. V.; Sklyarov, V. F.; Vyacheslavov, L. N. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Burdakov, A. V.; Sorokina, N. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Avenue, Novosibirsk 630092 (Russian Federation); Gavrilenko, D. E.; Kasatov, A. A.; Kandaurov, I. V.; Mekler, K. I.; Rovenskikh, A. F.; Trunev, Yu. A. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Kurkuchekov, V. V.; Kuznetsov, S. A. [Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Polosatkin, S. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Avenue, Novosibirsk 630092 (Russian Federation)
2015-12-15
There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70–110 keV for the electron energy, 1–10 MW for the beam power and 30–300 μs for its duration. The spectrum was measured in 75–230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.
Erosion of a relativistic electron beam propagating in a plasma channel
International Nuclear Information System (INIS)
Werner, P.W.; Schamiloglu, E.; Smith, J.R.; Struve, K.W.; Lipinski, R.J.
1994-01-01
A relativistic electron beam has propagated 91 m in a laser-ionized plasma channel across applied magnetic fields much larger than the geomagnetic field. Beam currents ranged from 0.3 to 1.0 kA and transverse magnetic field from 0.1 to 4.0 G. Beam degradation in the form of a shortening of the current pulse (erosion) was observed. The erosion processes were inductive and magnetic erosion. Observed total erosion rates are in agreement with the summation of the theoretical inductive and magnetic erosion rates. Magnetic erosion was enhanced when the beam radius was larger than the channel
Fan Ya Jun; Qiu Aici
2002-01-01
Experimental study on hard X-ray generation was carried out on Flash 2 accelerator, with the method of relativistic electron beams transported in a low pressure gas via azimuthal magnetic field and interacted with Ta target. At 47 cm transporting distance, the measured areal integral of hard X-ray dose rate was 2.1 x 10 sup 1 sup 0 Gy centre dot cm sup 2 /s, total areal integral of hard X-ray dose was 1843 Gy centre dot cm sup 2 , and X-ray convert rate was 108 Gy centre dot cm sup 2 /kJ
Electron Parametric Instabilities Driven by Relativistically Intense Laser Light in Plasma
Barr, H. C.; Mason, P.; Parr, D. M.
1999-08-01
A unified treatment of electron parametric instabilities driven by ultraintense laser light in plasma is described. It is valid for any intensity, polarization, plasma density, and scattering geometry. The method is applied to linearly polarized light in both underdense plasma and overdense plasma accessible by self-induced transparency. New options arise which are hybrids of stimulated Raman scattering, the two plasmon decay, the relativistic modulational and filamentation instabilities, and stimulated harmonic generation. There is vigorous growth over a wide range of wave numbers and harmonics.
Studies of high-current relativistic electron beam interaction with gas and plasma in Novosibirsk
Sinitsky, S. L.; Arzhannikov, A. V.; Burdakov, A. V.
2016-03-01
This paper presents an overview of the studies on the interaction of a high-power relativistic electron beam (REB) with dense plasma confined in a long open magnetic trap. The main goal of this research is to achieve plasma parameters close to those required for thermonuclear fusion burning. The experimental studies were carried over the course of four decades on various devices: INAR, GOL, INAR-2, GOL-M, and GOL-3 (Budker Institute of Nuclear Physics) for a wide range of beam and plasma parameters.
Studies of high-current relativistic electron beam interaction with gas and plasma in Novosibirsk
International Nuclear Information System (INIS)
Sinitsky, S. L.; Arzhannikov, A. V.; Burdakov, A. V.
2016-01-01
This paper presents an overview of the studies on the interaction of a high-power relativistic electron beam (REB) with dense plasma confined in a long open magnetic trap. The main goal of this research is to achieve plasma parameters close to those required for thermonuclear fusion burning. The experimental studies were carried over the course of four decades on various devices: INAR, GOL, INAR-2, GOL-M, and GOL-3 (Budker Institute of Nuclear Physics) for a wide range of beam and plasma parameters.
Studies of high-current relativistic electron beam interaction with gas and plasma in Novosibirsk
Energy Technology Data Exchange (ETDEWEB)
Sinitsky, S. L., E-mail: s.l.sinitsky@inp.nsk.su; Arzhannikov, A. V. [Budker Institute of Nuclear Physics, 11 Acad. Lavrentyev Ave, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova St., Novosibirsk, 630090 (Russian Federation); Burdakov, A. V. [Budker Institute of Nuclear Physics, 11 Acad. Lavrentyev Ave, Novosibirsk, 630090 (Russian Federation); Novosibirsk State Technical University, 20 Prospekt K. Marksa, Novosibirsk, 630073 (Russian Federation)
2016-03-25
This paper presents an overview of the studies on the interaction of a high-power relativistic electron beam (REB) with dense plasma confined in a long open magnetic trap. The main goal of this research is to achieve plasma parameters close to those required for thermonuclear fusion burning. The experimental studies were carried over the course of four decades on various devices: INAR, GOL, INAR-2, GOL-M, and GOL-3 (Budker Institute of Nuclear Physics) for a wide range of beam and plasma parameters.
International Nuclear Information System (INIS)
Key, M.H.; Campbell, E.M.; Cowan, T.E.; Hatchett, S.P.; Henry, E.A.; Koch, J.A.; Landgon, A.B.; Lasinski, B.F.; Lee, R.W.; MacKinnon, A.; Offenberger, A.; Pennington, D.M.; Perry, M.D.; Sangster, T.C.; Yasuike, K.; Snavely, R.; Roth, M.; Phillips, T.W.; Stoyer, M.A.; Wilks, S.C.; Singh, M.S.
1999-01-01
The interaction of laser radiation with solid targets at 1 petawatt power and intensity up to 3x10 20 Wcm -2 has been studied with emphasis on relativistic electrons and high energy ions. Secondary effects including Bremsstrahlung radiation, nuclear interactions and heating have been characterized. A collimated beam of protons with up to 55 MeV energy is emitted normal to the rear surface of thin targets and its characteristics and origin are discussed. The significance of the data for radiography, fast ignition and proton beam applications is summarized
Sakharov, A. S.
2017-11-01
Compact expressions are derived for the nonlocal permittivity tensor of weakly relativistic plasma in a 2D nonuniform magnetic field near the resonances at the second harmonic of the electron cyclotron frequency for an extraordinary wave and at the first harmonic for an ordinary wave. It is shown that the wave equation with allowance for the obtained thermal correction to the permittivity tensor in the form of a differential operator in transverse (with respect to the external magnetic field) coordinates possesses an integral in the form of the energy conservation law.
Relativistic electron dropouts by pitch angle scattering in the geomagnetic tail
Directory of Open Access Journals (Sweden)
J. J. Lee
2006-11-01
Full Text Available Relativistic electron dropout (RED events are characterized by fast electron flux decrease at the geostationary orbit. It is known that the main loss process is non adiabatic and more effective for the high energy particles. RED events generally start to occur at midnight sector and propagate to noon sector and are correlated with magnetic field stretching. In this paper, we discuss this kind of event can be caused from pitch angle diffusion induced when the gyro radius of the electrons is comparable to the radius of curvature of the magnetic field and the magnetic moment is not conserved any more. While this process has been studied theoretically, the question is whether electron precipitation could be explained with this process for the real field configuration. This paper will show that this process can successfully explain the precipitation that occurred on 14 June 2004 observed by the low-altitude (680 km polar orbiting Korean satellite, STSAT-1. In this precipitation event, the energy dispersion showed higher energy electron precipitation occurred at lower L values. This feature is a good indicator that precipitation was caused by the magnetic moment scattering in the geomagnetic tail. This interpretation is supported by the geosynchronous satellite GOES observations that showed significant magnetic field distortion occurred on the night side accompanying the electron flux depletion. Tsyganenko-01 model also shows the magnetic moment scattering could occur under the geomagnetic conditions existing at that time. We suggest the pitch angle scattering by field curvature violating the first adiabatic invariant as a possible candidate for loss mechanism of relativistic electrons in radiation belt.
Relativistic electron acceleration by whistler-mode chorus emissions associated with substorms
Omura, Yoshiharu
Whistler-mode chorus emissions are generated at the geomagnetic equator by injection of energetic electrons into the inner magnetosphere during geomagnetically disturbed periods of substorms[1]. We perform test particle simulations assuming whistler-mode chorus wave packets that are generated at the geomagnetic equator propagate away from the equator in both poleward directions. While electrons in the energy range 10 - 100 keV are primarily responsible for the generation of chorus waves through pitch angle diffusion into the loss cone, it has been found that a fraction of the higher-energy electrons from a few hundred keV to a few MeV are effectively accelerated by chorus due to special nonlinear trapping processes called relativistic turning acceleration (RTA)[2] and ultra-relativistic acceleration (URA)[3]. In the present study we confirm that the RTA and URA processes take place for a wave packet with variable frequency such as that occurring in a rising tone of chorus emissions. We study the efficiency of the RTA and URA processes for different particle energies. A Green's function method is used to describe the evolution of the particle energy distribution function. The RTA and URA processes due to chorus emissions create a high-energy tail in the electron energy distribution function[4]. The shape of the high-energy tail is determined by the distribution function of the seed electrons in the lower-energy range. The RTA and URA can accelerate electrons in a much shorter timescale than that estimated by quasi-linear diffusion theory, e.g., it typically takes tens of minutes to hours for a few keV seed electrons to be accelerated to energies of a few MeV by RTA and URA. References 1. Y. Omura, Y. Katoh, and D. Summers, Theory and simulation of the generation of whistlermode chorus, J. Geophys. Res., in press. 2. Y. Omura, N. Furuya, D. Summers, J Geophys. Res., Vol. 112, A06236, doi:10.1029/2006JA012243, 2007. 3. D. Summers and Y. Omura, Geophys. Res. Lett., 34
A self-consistent nonlinear theory of resistive-wall instability in a relativistic electron beam
International Nuclear Information System (INIS)
Uhm, H.S.
1994-01-01
A self-consistent nonlinear theory of resistive-wall instability is developed for a relativistic electron beam propagating through a grounded cylindrical resistive tube. The theory is based on the assumption that the frequency of the resistive-wall instability is lower than the cutoff frequency of the waveguide. The theory is concentrated on study of the beam current modulation directly related to the resistive-wall klystron, in which a relativistic electron beam is modulated at the first cavity and propagates downstream through the resistive wall. Because of the self-excitation of the space charge waves by the resistive-wall instability, a highly nonlinear current modulation of the electron beam is accomplished as the beam propagates downstream. A partial integrodifferential equation is obtained in terms of the initial energy modulation (ε), the self-field effects (h), and the resistive-wall effects (κ). Analytically investigating the partial integrodifferential equation, a scaling law of the propagation distance z m at which the maximum current modulation occurs is obtained. It is found in general that the self-field effects dominate over the resistive-wall effects at the beginning of the propagation. As the beam propagates farther downstream, the resistive-wall effects dominate. Because of a relatively large growth rate of the instability, the required tube length of the klystron is short for most applications
Sultana, S.; Schlickeiser, R.
2018-02-01
A three component degenerate relativistic quantum plasma (consisting of relativistically degenerate electrons, nondegenerate inertial light nuclei, and stationary heavy nuclei) is considered to model the linear wave and also the electrostatic solitary waves in the light nuclei-scale length. A well-known normal mode analysis is employed to investigate the linear wave properties. A mechanical-motion analog (Sagdeev-type) pseudo-potential approach, which reveals the existence of large amplitude solitary excitations, is adopted to study the nonlinear wave properties. Only the positive potential solitary excitations are found to exist in the plasma medium under consideration. The basic properties of the arbitrary amplitude electrostatic acoustic modes in the light nuclei-scale length and their existence domain in terms of soliton speed (Mach number) are examined. The modifications of solitary wave characteristics and their existence domain with the variation of different key plasma configuration parameters (e.g., electrons degeneracy parameter, inertial light nuclei number density, and degenerate electron number density) are also analyzed. Our results, which may be helpful to explain the basic features of the nonlinear wave propagation in multi-component degenerate quantum plasmas, in connection with astrophysical compact objects (e.g., white dwarfs) are briefly discussed.
Sarfraz, M.; Farooq, H.; Abbas, G.; Noureen, S.; Iqbal, Z.; Rasheed, A.
2018-03-01
Thermal momentum space anisotropy is ubiquitous in many astrophysical and laboratory plasma environments. Using Vlasov-Maxwell's model equations, a generalized polarization tensor for a collisionless ultra-relativistic unmagnetized electron plasma is derived. In particular, the tensor is obtained by considering anisotropy in the momentum space. The integral of moments of Fermi-Dirac distribution function in terms of Polylog functions is used for describing the border line plasma systems (T/e TF e ≈1 ) comprising arbitrary electron degeneracy, where Te and TF e, are thermal and Fermi temperatures, respectively. Furthermore, the effects of variation in thermal momentum space anisotropy on the electron equilibrium number density and the spectrum of electromagnetic waves are analyzed.
Atomic and free electrons in a strong light field
Fedorov, Mikhail V
1997-01-01
This book presents and describes a series of unusual and striking strong-field phenomena concerning atoms and free electrons. Some of these phenomena are: multiphoton stimulated bremsstrahlung, free-electron lasers, wave-packet physics, above-threshold ionization, and strong-field stabilization in Rydberg atoms. The theoretical foundations and causes of the phenomena are described in detail, with all the approximations and derivations discussed. All the known and relevant experiments are described too, and their results are compared with those of the existing theoretical models.An extensive ge
Theory of Free Electron Laser Instability in a Relativistic Annular Electron Beam.
1980-08-01
constant density no , the inequality in Eq. (3) can be expressed in the equivalent form 2p10/c/ << R0 /a, (4) where 02 4 n e2/ ybm is the relativistic...term p z/ym in Eq. (67) by Pz P b + z (71) y7m bm Ybm 2 2 21/2 where b -(l+ pb/m c ) Substituting Eqs. (68) - (71) into Eq. (67), we obtain (J) (0) 2v
Radiative electron-atom collision in a strong laser field
International Nuclear Information System (INIS)
Faisal, F.H.M.
1984-01-01
The comment is concerned with certain current problems and prospects in the theory of electron-atom collision in a strong radiation field. High energy off-shell electron-photon excitation of atoms; low-energy e-atom radiative scattering; steady state input distribution; typical distribution; low energy phenomena; and extensions of the close coupling and the algebraic methods, are all discussed. (U.K.)
Relativistic electron transport in wire and foil targets driven by intense short pulse lasers
Mason, R. J.; Stephens, R. B.; Wei, M.; Freeman, R. R.; Hill, J.; van Woerkom, L. D.
2006-10-01
We model intense laser driven electron transport in wires and foils with the new implicit hybrid code e-PLAS. We focus on background plasma heating for Fast Ignitor applications. The model tracks collisional relativistic PIC electrons undergoing scatter and drag in a background plasma of colliding cold electron and ion Eulerian fluids. Application to 10 μm diameter, 250 μm long, fully ionized carbon wires with an attached cone [Kodama et al. Nature 432 1005 (2004)], exposed to 1 ps, 10^19 W/cm^2 pulses in a 30 μm centered spot, directly calculates resistive Joule heating of the background electrons in the wire to 1.7 KeV. 150 MG magnetic fields arise at the wire surfaces corresponding to hot electron flow outside the wire and a return electron flow just within it. Shorter wires (25 μm) exhibit hot electron recycling. Preliminary simulations indicate that reduction of the cone to a 30 μm diameter nail head produces little change in these results. We also report on tapered wires, wires attached to foils, and the modifying effects of pre-plasma on electron transport into the foils.
Mori, M.; Kando, M.; Daito, I.; Kotaki, H.; Hayashi, Y.; Yamazaki, A.; Ogura, K.; Sagisaka, A.; Koga, J.; Nakajima, K.; Daido, H.; Bulanov, S. V.; Kimura, T.
2006-01-01
The regimes of quasi-mono-energetic electron beam generation were experimentally studied in the sub-relativistic intensity laser plasma interaction. The observed electron acceleration regime is unfolded with two-dimensional-particle-in-cell simulations of laser-wakefield generation in the self-modulation regime.
Energy Technology Data Exchange (ETDEWEB)
Mori, M. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan)]. E-mail: mori.michiaki@jaea.go.jp; Kando, M. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Daito, I. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Kotaki, H. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Hayashi, Y. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Yamazaki, A. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Ogura, K. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Sagisaka, A. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Koga, J. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Nakajima, K. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Daido, H. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan); Bulanov, S.V.; Kimura, T. [Advanced Photon Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizu, Kyoto 619-0215 (Japan)
2006-07-31
The regimes of quasi-monoenergetic electron beam generation were experimentally studied in the sub-relativistic intensity laser plasma interaction. The observed electron acceleration regime is unfolded with two-dimensional-particle-in-cell simulations of laser-wakefield generation in the self-modulation regime.
The Electron-Phonon Interaction in Strongly Correlated Systems
International Nuclear Information System (INIS)
Castellani, C.; Grilli, M.
1995-01-01
We analyze the effect of strong electron-electron repulsion on the electron-phonon interaction from a Fermi-liquid point of view and show that the electron-electron interaction is responsible for vertex corrections, which generically lead to a strong suppression of the electron-phonon coupling in the v F q/ω >>1 region, while such effect is not present when v F q/ω F is the Fermi velocity and q and ω are the transferred momentum and frequency respectively. In particular the e-ph scattering is suppressed in transport properties which are dominated by low-energy-high-momentum processes. On the other hand, analyzing the stability criterion for the compressibility, which involves the effective interactions in the dynamical limit, we show that a sizable electron-phonon interaction can push the system towards a phase-separation instability. Finally a detailed analysis of these ideas is carried out using a slave-boson approach for the infinite-U three-band Hubbard model in the presence of a coupling between the local hole density and a dispersionless optical phonon. (author)
X-ray radiation generated by a beam of relativistic electrons in composite structure
Blazhevich, S. V.; Noskov, A. V.
2018-04-01
The dynamic theory of coherent X-ray radiation generated by a beam of relativistic electrons in the three-layer structure consisting of an amorphous layer, a vacuum (air) layer and a single crystal has been developed. The phenomenon description is based on two main radiation mechanisms, namely, parametric X-ray radiation (PXR) and diffracted transition radiation (DTR). The possibility to increase the spectral-angular density of DTR under the condition of constructive interference of the transition radiation waves from different boundaries of such a structure has been demonstrated. It is shown that little changes in the layers thicknesses should not cause a considerable change in the interference picture, for example, the transition of constructive interference into destructive one. It means that in the considered process the conditions of constructive interference are enough stable to use them for increasing the intensity of X-ray source that can be created based on the interaction of relativistic electrons with such a structure.
Relativistic Electron Acceleration by Surface Plasma Waves in the High Intensity Regime
Zhu, Xiaoming; Cerchez, Mirela; Swantusch, Marco; Aurand, Bastian; Prasad, Rajendra; Andreev, Alexander; Willi, Oswald
2017-10-01
High field plasmonics is one of the new research fields which has synergetically benefited from the advances in laser technology. The availability of radiation fields of intensities exceeding 1018 W/cm2 brought plasmonics into a new regime where relativistic and nonlinear effects start to dominate the dynamics of the surface plasma waves (SPWs). Moreover, surface plasma waves are a very efficient route to transfer the laser energy to the secondary sources including laser driven particle and radiation beams and to control and optimize the physical properties of these sources. We present here experimental evidence of a novel regime of the SPWs excitation by ultra-high intensity laser field (I>1020 W/cm2) on grating targets and its effect on high energy surface electron acceleration. The peak of the electron emission was detected at a laser incidence angle of 45°. The results indicate new conditions for resonant excitation of SPWs since in the limit of the linear regime (moderate intensities of 1019 W/cm2 and step preplasma profile), the resonance angle is predicted at 30°. 2D PIC simulations and a novel analytical model confirm the experimental data and reveal that, at laser intensities above 1020W/cm2, nonlinearities induced by the preplasma condition and relativistic effects change the SPWs resonance.
Anomalous electron loading in SLAC 5045 klystron and relativistic klystron input cavities
International Nuclear Information System (INIS)
Koontz, R.F.; Fowkes, R.W.; Lavine, T.L.; Miller, R.H.; Vlieks, A.E.
1989-03-01
Recent studies of RF breakup and instability in the SLAC 5045 klystrons have revealed that many production klystrons show loading of the input cavity by low energy electrons even under cold cathode no beam conditions. Sometime after the onset of the RF drive pulse, the input cavity absorbs a portion of the incident RF drive that would otherwise be reflected from the not-beam-loaded cavity. This power absorption is a function of drive level, and of axial magnetic field surrounding the cavity. No power absorption is present when the axial magnetic field is zero. This same phenomenon has been observed in the input cavity of relativistic klystron experiments being conducted as part of the SLAC-LBL-LLNL development program. The phenomenon may be associated with RF breakup and RF instability in SLAC 5045 klystrons, and with unstable pulse shortening in the relativistic klystron experiments. This paper outlines some old and new observations of microwave beam device malfunctions that probably are associated with low energy electron fluxes in the vacuum environments of microwave power devices. 2 refs., 5 figs
Anomalous electron loading in SLAC 5045 klystron and relativistic klystron input cavities
Energy Technology Data Exchange (ETDEWEB)
Koontz, R.F.; Fowkes, R.W.; Lavine, T.L.; Miller, R.H.; Vlieks, A.E.
1989-03-01
Recent studies of RF breakup and instability in the SLAC 5045 klystrons have revealed that many production klystrons show loading of the input cavity by low energy electrons even under cold cathode no beam conditions. Sometime after the onset of the RF drive pulse, the input cavity absorbs a portion of the incident RF drive that would otherwise be reflected from the not-beam-loaded cavity. This power absorption is a function of drive level, and of axial magnetic field surrounding the cavity. No power absorption is present when the axial magnetic field is zero. This same phenomenon has been observed in the input cavity of relativistic klystron experiments being conducted as part of the SLAC-LBL-LLNL development program. The phenomenon may be associated with RF breakup and RF instability in SLAC 5045 klystrons, and with unstable pulse shortening in the relativistic klystron experiments. This paper outlines some old and new observations of microwave beam device malfunctions that probably are associated with low energy electron fluxes in the vacuum environments of microwave power devices. 2 refs., 5 figs.
Electron with orbital angular momentum in a strong laser wave
Karlovets, Dmitry V.
2012-12-01
Electrons carrying orbital angular momentum (OAM) have recently been discovered theoretically and obtained experimentally, which opens up possibilities for using them in high-energy physics. We consider such a twisted electron moving in the external field of a plane electromagnetic wave and study how this field influences the electron's OAM. Being motivated by the development of high-power lasers, we focus our attention on a classically strong-field regime for which -e2A2¯/(me2c4)≳1. It is shown that, along with the well-known “plane-wave” Volkov solution, the Dirac equation also has the “non-plane-wave” solutions, which possess OAM and spin-orbit coupling and generalize the free-electron's Bessel states. Motion of an electron with OAM in a circularly polarized laser wave reveals a twofold character: the wave-packet center moves along a classical helical trajectory with some quantum transverse broadening (due to OAM) existing even for a free electron. Using the twisted states, we calculate the electron's total angular momentum and predict its shift in the strong-field regime, which is analogous to the well-known shifts of the electron's momentum and mass (and to a less-known shift of its spin) in intense fields. Since the electron's effective angular momentum is conserved in a plane wave, as well as in some more general field configurations, we discuss several possibilities for accelerating nonrelativistic twisted electrons by using focused and combined electromagnetic fields.
Attosecond Electron Wave Packet Dynamics in Strong Laser Fields
International Nuclear Information System (INIS)
Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier, A.; Lopez-Martens, R.; Valentin, C.; Balcou, Ph.; Kazamias, S.; Mauritsson, J.; Gaarde, M. B.; Schafer, K. J.; Mairesse, Y.; Wabnitz, H.; Salieres, P.
2005-01-01
We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (∼20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes
Atomic and Free Electrons in a Strong Light Field
International Nuclear Information System (INIS)
Fedorov, Mikhail V.
1998-02-01
This book presents and describes a series of unusual and striking strong-field phenomena concerning atoms and free electrons. Some of these phenomena are: multiphoton stimulated Bremsstrahlung, free-electron lasers, ave-packet physics, above-threshold ionization, and strong-field stabilization in Rydberg atoms. The theoretical foundations and causes of the phenomena are described in detail, with all the approximations and derivations discussed. All the known and relevant experiments are described oo, and their results are compared with those of the existing theoretical models. An extensive general theoretical introduction gives a good basis for subsequent parts of the book and is an independent and self-sufficient description of the most efficient theoretical methods of the strong-field and multiphoton physics. This book can serve as a textbook for graduate students
International Nuclear Information System (INIS)
Ouyang, Zhengbiao; Zhang, Shi-Chang
2014-01-01
In a free-electron laser the ‘natural focusing’ effect of a three-dimensional wiggler is too weak to confine the transport of a relativistic electron beam when the beam has a high current and consequently an external focusing system is often needed. In this paper we study the focusing peculiarities of an ion-channel guide field on an electron beam. Nonlinear simulations of an electron beam transport show that, compared to an axial guide magnetic field, the ion-channel guide field results in smaller velocity–space and configuration–space spreads. The intrinsic mechanism of this physical phenomenon is that the ion-channel guide field confines the trajectory of the electron motion resulting in a smaller instantaneous curvature radius and a slighter curvature-center excursion than an axial guide magnetic field does. It is also found that, unlike with an axial guide magnetic field, over-focusing may occur if the ion-channel guide field is too strong. (paper)
Omura, Y.; Hsieh, Y. K.; Foster, J. C.; Erickson, P. J.; Kletzing, C.; Baker, D. N.
2017-12-01
A recent test particle simulation of obliquely propagating whistler mode wave-particle interaction [Hsieh and Omura, 2017] shows that the perpendicular wave electric field can play a significant role in trapping and accelerating relativistic electrons through Landau resonance. A further theoretical and numerical investigation verifies that there occurs nonlinear wave trapping of relativistic electrons by the nonlinear Lorentz force of the perpendicular wave magnetic field. An electron moving with a parallel velocity equal to the parallel phase velocity of an obliquely propagating wave basically see a stationary wave phase. Since the electron position is displaced from its gyrocenter by a distance ρ*sin(φ), where ρ is the gyroradius and φ is the gyrophase, the wave phase is modulated with the gyromotion, and the stationary wave fields as seen by the electron are expanded as series of Bessel functions Jn with phase variations n*φ. The J1 components of the wave electric and magnetic fields rotate in the right-hand direction with the gyrofrequency, and they can be in resonance with the electron undergoing the gyromotion, resulting in effective electron acceleration and pitch angle scattering. We have performed a subpacket analysis of chorus waveforms observed by the Van Allen Probes [Foster et al., 2017], and calculated the energy gain by the cyclotron acceleration through Landau resonance. We compare the efficiencies of accelerations by cyclotron and Landau resonances in typical events of rapid electron acceleration observed by the Van Allen Probes.References:[1] Hsieh, Y.-K., and Y. Omura (2017), Nonlinear dynamics of electrons interacting with oblique whistler mode chorus in the magnetosphere, J. Geophys. Res. Space Physics, 122, 675-694, doi:10.1002/2016JA023255.[2] Foster, J. C., P. J. Erickson, Y. Omura, D. N. Baker, C. A. Kletzing, and S. G. Claudepierre (2017), Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear
Removal of NOx by pulsed, intense relativistic electron beam in distant gas chamber
International Nuclear Information System (INIS)
Imada, Go; Sakurai, Tomoki; Jiang Weihua; Yatsui, Kiyoshi
2002-01-01
Removal of NOx has been studied using a pulsed, intense relativistic electron beam (IREB). The dependence of NOx concentration and the removal efficiency of NOx on the number of IREB shot have been investigated within a distant gas chamber spatially isolated from the electron beam source. The distant gas chamber is filled up with a dry-air-balanced NO gas mixture with the pressure of 270 kPa, and is irradiated by the IREB (2 MeV, 30 A, 35 ns) passing through a 1.6-m-long atmosphere. With the initial NO concentration of 88 ppm, ∼ 70 % of NOx is successfully removed by firing 10 shots of IREB. The NOx removal efficiency has been found to be 50-155 g/kWh
Couillaud, C
2002-01-01
This paper is concerned with the production of X-ray transition radiation when a relativistic electron crosses the interface between two media of different permittivities at the grazing incidence. The production yields are derived analytically when a thick interface is considered and are compared with those obtained when the electron crosses the interface at normal incidence. The production of X-ray photons having an energy between two photoabsorption edges or close to a photoabsorption edge is also investigated. The main features of the transition radiation produced are then exhibited and it is shown that the intensity can be increased by many orders of magnitude. We also show that, at grazing incidence, the backward transition radiation has an intensity close to the forward emission one, contrary to the normal incidence case. The production of quasi-monochromatic radiation is also presented. Finally, the production of X-ray transition radiation using a multilayer radiator is considered and compared in both ...
Cascaded modulator-chicane modules for optical manipulation of relativistic electron beams
Directory of Open Access Journals (Sweden)
Erik Hemsing
2013-01-01
Full Text Available A sequential arrangement of three pairs of modulators and dispersive sections that performs precise manipulation of a relativistic electron beam’s longitudinal phase space is described. We show that using only a single laser wavelength, this scheme acts as a waveform synthesizer through linearization of local regions of phase space to generate sawtooth, triangular, and square wave-type distributions. It also acts as an optical analog of an rf function generator to generate intense coherent radiation that has periodic triangle and square field profiles at the optical wavelength. The same setup can also be used to improve the high-harmonic bunching factors in echo-enabled harmonic generation schemes up to 25% and to produce a bunching factor above 90% at the laser fundamental wavelength for high-efficiency capture in inverse free electron laser acceleration applications.
International Nuclear Information System (INIS)
Andreev, A A; Galkin, A L; Kalashnikov, M P; Korobkin, V V; Romanovsky, Mikhail Yu; Shiryaev, O B
2011-01-01
We study the motion of an electron and emission of electromagnetic waves by an electron in the field of a relativistically intense laser pulse. The dynamics of the electron is described by the Newton equation with the Lorentz force in the right-hand side. It is shown that the electrons may be ejected from the interaction region with high energy. The energy spectrum of these electrons and the technique of using the spectrum to assess the maximal intensity in the focus are analysed. It is found that electromagnetic radiation of an electron moving in an intense laser field occurs within a small angle around the direction of the electron trajectory tangent. The tangent quickly changes its direction in space; therefore, electromagnetic radiation of the electron in the far-field zone in a certain direction in the vicinity of the tangent is a short pulse with a duration as short as zeptoseconds. The calculation of the temporary and spectral distribution of the radiation field is carried out. (superintense laser fields)
International Nuclear Information System (INIS)
Panek, P.; Kaminski, J.Z.; Ehlotzky, F.
2002-01-01
We reconsider the relativistic scattering of electrons by an atom, being approximated by a static potential, in an extremely powerful electromagnetic plane wave of frequency ω and linear polarization ε. Since to a first order of approximation spin effects can be neglected, we first describe the scattered electron by the Gordon solution of the Klein-Gordon equation. Then we investigate the same scattering process by including the spin effects, using for the electron the Volkov solution of the Dirac equation. For sufficiently energetic electrons, the first-order Born approximation can be employed to represent the corresponding scattering matrix element. We compare the results of the differential cross sections of induced and inverse bremsstrahlung, evaluated from both approximations, for various parameter values and angular configurations and we find that in most cases the spin effects are marginal, even at very high laser power. On the other hand, we recover the various asymmetries in the angular distributions of the scattered electrons and their respective energies due to the laser-induced drift motion of the electrons in the direction of propagation of the radiation field, thus confirming the findings of our previous work [Phys. Rev. A 59, 2105 (1999); Laser Physics 10, 163 (2000)
Propagation of a laser-driven relativistic electron beam inside a solid dielectric.
Sarkisov, G S; Ivanov, V V; Leblanc, P; Sentoku, Y; Yates, K; Wiewior, P; Chalyy, O; Astanovitskiy, A; Bychenkov, V Yu; Jobe, D; Spielman, R B
2012-09-01
Laser probe diagnostics: shadowgraphy, interferometry, and polarimetry were used for a comprehensive characterization of ionization wave dynamics inside a glass target induced by a laser-driven, relativistic electron beam. Experiments were done using the 50-TW Leopard laser at the University of Nevada, Reno. We show that for a laser flux of ∼2 × 10(18) W/cm2 a hemispherical ionization wave propagates at c/3 for 10 ps and has a smooth electron-density distribution. The maximum free-electron density inside the glass target is ∼2 × 10(19) cm-3, which corresponds to an ionization level of ∼0.1%. Magnetic fields and electric fields do not exceed ∼15 kG and ∼1 MV/cm, respectively. The electron temperature has a hot, ringlike structure with a maximum of ∼0.7 eV. The topology of the interference phase shift shows the signature of the "fountain effect", a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields driven by laser. The very low ionization observed after the laser heating pulse suggests a fast recombination on the sub-ps time scale.
Directory of Open Access Journals (Sweden)
S. W. H. Cowley
2006-03-01
Full Text Available Recent spectroscopic observations of Jupiter's "main oval" auroras indicate that the primary auroral electron beam is routinely accelerated to energies of ~100 keV, and sometimes to several hundred keV, thus approaching the relativistic regime. This suggests the need to re-examine the classic non-relativistic theory of auroral electron acceleration by field-aligned electric fields first derived by Knight (1973, and to extend it to cover relativistic situations. In this paper we examine this problem for the case in which the source population is an isotropic Maxwellian, as also assumed by Knight, and derive exact analytic expressions for the field-aligned current density (number flux and kinetic energy flux of the accelerated population, for arbitrary initial electron temperature, acceleration potential, and field strength beneath the acceleration region. We examine the limiting behaviours of these expressions, their regimes of validity, and their implications for auroral acceleration in planetary magnetospheres (and like astrophysical systems. In particular, we show that for relativistic accelerating potentials, the current density increases as the square of the minimum potential, rather than linearly as in the non-relativistic regime, while the kinetic energy flux then increases as the cube of the potential, rather than as the square.
Neutrino-electron processes in a strongly magnetized thermal plasma
Hardy, S J; Hardy, Stephen J.; Thoma, Markus H.
2001-01-01
We present a new method of calculating the rate of neutrino-electron interactions in a strong magnetic field based on finite temperature field theory. Using this method, in which the effect of the magnetic field on the electron states is taken into account exactly, we calculate the rates of all of the lowest order neutrino-electron interactions in a plasma. As an example of the use of this technique, we explicitly calculate the rate at which neutrinos and antineutrinos annihilate in a highly magnetized plasma, and compare that to the rate in an unmagnetized plasma. The most important channel for energy deposition is the gyromagnetic absorption of a neutrino-antineutrino pair on an electron or positron in the plasma ($\
Ikramullah, Ahmad, Rashid; Sharif, Saqib; Khattak, Fida Younus
2018-01-01
The interaction of Circularly Polarized Electro-Magnetic (CPEM) waves with a 4-component relativistic quantum plasma is studied. The plasma constituents are: relativistic-degenerate electrons and positrons, dynamic degenerate ions, and Thomas-Fermi distributed electrons in the background. We have employed the Klein-Gordon equations for the electrons as well as for the positrons, while the ions are represented by the Schrödinger equation. The Maxwell and Poisson equations are used for electromagnetic waves. Three modes are observed: one of the modes is associated with the electron acoustic wave, a second mode at frequencies greater than the electron acoustic wave mode could be associated with the positrons, and the third one at the lowest frequencies could be associated with the ions. Furthermore, Stimulated Raman Scattering (SRS), Modulational, and Stimulated Brillouin Scattering (SBS) instabilities are studied. It is observed that the growth rates of both the SRS and SBS instabilities decrease with increase in the quantum parameter of the plasma. It is also observed that the scattering spectra in both the SRS and SBS get restricted to very small wavenumber regions. It is shown that for low amplitude CPEM wave interaction with the quantum plasma, the positron concentration has no effect on the SRS and SBS spectra. In the case of large amplitude CPEM wave interaction, however, one observes spectral changes with varying positron concentrations. An increase in the positron concentration also enhances the scattering instability growth rates. Moreover, the growth rate first increases and then decreases with increasing intensity of the CPEM wave, indicating an optimum value of the CPEM wave intensity for the growth of these scattering instabilities. The modulational instability also shows dependence on the quantum parameter as well as on the positron concentration.
Relativistic electron beam interaction and $K_{\\alpha}$-generation in solid targets
Fill, E; Eder, D; Eidmann, K; Saemann, A
1999-01-01
When fs laser pulses interact with solid surfaces at intensities I lambda /sup 2/ >10/sup 18/ W/cm/sup 2/ mu m/sup 2/, collimated relativistic electron beams are generated. These electrons can be used for producing intense X-radiation (bremsstrahlung or K/sub alpha /) for pumping an innershell X-ray laser. The basic concept of such a laser involves the propagation of the electron beam in a material which converts electron energy into appropriate pump photons. Using the ATLAS titanium-sapphire laser at Max-Planck-Institut fur Quantenoptik, we investigate the generation of hot electrons and of characteristic radiation in copper. The laser (200 mJ/130 fs) is focused by means of an off-axis parabola to a diameter of about 10 mu m. By varying the position of the focus, we measure the copper K/sub alpha /-yield as a function of intensity in a range from 10/sup 15/ to 2 x 10/sup 18/ W/cm/sup 2/ while keeping the laser pulse energy constant. Surprisingly, the highest emission is obtained at an intensity of about 10/s...
Kuang, Xiang-Jun; Wang, Xin-Qiang; Liu, Gao-Bin
2015-02-01
Under the framework of DFT, an all-electron scalar relativistic calculation on the adsorption of Aun (n = 1-13) clusters toward methanol molecule has been performed with the generalized gradient approximation at PW91 level. Our calculation results reveal that the small gold cluster would like to bond with oxygen of methanol molecule at the edge of gold cluster plane. After adsorption, the chemical activities of hydroxyl group and methyl group are enhanced to some extent. The even-numbered AunCH3OH cluster with closed-shell electronic configuration is relatively more stable than the neighboring odd-numbered AunCH3OH cluster with open-shell electronic configuration. All the AunCH3OH clusters prefer low spin multiplicity (M = 1 for even-numbered AuNCH3OH clusters, M = 2 for odd-numbered AunCH3OH clusters) and the magnetic moments are mainly contributed by gold atoms. The odd-even alterations of magnetic moments and electronic configurations can be observed clearly and may be simply understood in terms of the electron pairing effect.
Cao, Xing; Shprits, Yuri Y.; Ni, Binbin; Zhelavskaya, Irina S.
2017-01-01
Electron flux in the Earth’s outer radiation belt is highly variable due to a delicate balance between competing acceleration and loss processes. It has been long recognized that Electromagnetic Ion Cyclotron (EMIC) waves may play a crucial role in the loss of radiation belt electrons. Previous theoretical studies proposed that EMIC waves may account for the loss of the relativistic electron population. However, recent observations showed that while EMIC waves are responsible for the signific...
Magnetic properties of metallic impurities with strongly correlated electrons
Czech Academy of Sciences Publication Activity Database
Janiš, Václav; Ringel, Matouš
2009-01-01
Roč. 115, č. 1 (2009), s. 30-35 ISSN 0587-4246 R&D Projects: GA ČR GA202/07/0644 Institutional research plan: CEZ:AV0Z10100520 Keywords : And erson impurity * strong electron correlations * spin-polarized solution * three-channel parquet equations * magnetic field Subject RIV: BE - Theoretical Physics Impact factor: 0.433, year: 2009 http://przyrbwn.icm.edu.pl/APP/ABSTR/115/a115-1-5.html
Strong field transient manipulation of electronic states and bands
Directory of Open Access Journals (Sweden)
I. Crassee
2017-11-01
Full Text Available In the present review, laser fields are so strong that they become part of the electronic potential, and sometimes even dominate the Coulomb contribution. This manipulation of atomic potentials and of the associated states and bands finds fascinating applications in gases and solids, both in the bulk and at the surface. We present some recent spectacular examples obtained within the NCCR MUST in Switzerland.
Multiorbital simplified parquet equations for strongly correlated electrons
Czech Academy of Sciences Publication Activity Database
Augustinský, Pavel; Janiš, Václav
2011-01-01
Roč. 83, č. 3 (2011), "035114-1"-"035114-13" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GC202/07/J047 Institutional research plan: CEZ:AV0Z10100520 Keywords : multi-orbital model * strongly correlated electrons * parquet equations * Kondo regime Subject RIV: BE - Theoretical Physics Impact factor: 3.691, year: 2011 http://prb.aps.org/abstract/PRB/v83/i3/e035114
Evaluating the Role and Effects of Precipitation on Relativistic Electron Losses during Storms
Chen, Y.; Fu, X.
2016-12-01
Theoretic studies have suggested that during storm times various waves (e.g., whistler-mode chorus and electromagnetic ion cyclotron waves) can cause significant precipitation of relativistic ( MeV) electrons that are originally trapped inside the outer radiation belt. However, the role of precipitation and its quantitative contribution to the losses of outer-belt electrons remain open questions. In this study, we tackle these questions by systemically examining the latest wave and electron in-situ, simultaneous observations made at different altitudes by Van Allen Probes from near equator, NOAA POES at low Earth orbits near/across electron loss cone, and BARREL under the mesosphere. After calibrating with DEMTER observations, we first confirm and quantify the response of POES MEPED proton channels to MeV electrons. Next, we identify a list of precipitation events from BARREL and POES measurements, examine the temporal adn spatial relation between the two data sets, and estimate the intensities of electron precipitation with ascertained uncertainties. Then, from Van Allen Probes data, we select another list of dropout events during storms. By cross checking the above two lists, we are able to determine the causal relation between precipitation and dropouts through individual case as well as statistical studies so as to quantify the contributions from precipitation. This study mainly focuses on the relatively small L-shells with positive phase space density radial gradient in order to alleviate the impacts from outward radial diffusion and adiabatic effects. Based upon the recent discovery of cross-energy cross-pitch angle coherence, we pay particular attention to the cross-term diffusions which may account for the extra "loss" needed by observed MeV electron dropouts. Results from this observational study will advance our knowledge on the loss mechanism of outer-belt electrons, and thus lay down another stepping stone towards high-fidelity physics-based models for
PREFACE: Introduction to Strongly Correlated Electrons in New Materials
Kusmartsev, Feo V.
2003-09-01
The discovery of new natural and artificial materials has revolutionized condensed matter physics and our views on the role of correlations between electrons. Novel properties such as high-temperature superconductivity and colossal magnetoresistance discovered in these materials have overturned our conventional representations of condensed matter physics and pushed us to reconsider many well-established concepts. For example, we must treat the Coulomb interaction between electrons far beyond perturbation theory; we must recall long-forgotten ideas of electronic phase separation introduced originally by Nagaev in the 1960s; we must reconsider the role of electron--phonon and electron--magnon interactions, orbital degrees of freedom, the Rashba effect and many other aspects of condensed matter physics that are becoming increasingly important. In many novel materials, such as the two-dimensional electron gas, the energy associated with the Coulomb interaction is typically of the order of (or even larger than) the kinetic energy of electrons or the Fermi energy. Therefore perturbation theory and associated renormalization group methods are not applicable to these situations and we may expect to find a novel state of matter associated with correlation effects. It is worth mentioning the known examples of these states proposed recently, such as marginal Fermi liquids, novel metal--insulator phase transitions in the two-dimensional electron gas associated with new metallic and insulating states, structured liquids, microscopic electronic phase separations, stripes, strings, polarons and others. The discussion of these states is now on the frontier of modern condensed matter physics and is partially covered in this special issue. The demand to treat the Coulomb interaction properly has stimulated a development of many-body theory, which considers correlations as fully as possible. Strong correlations may play an important role in the dynamics of the electronic system. In a
Self-focusing of electromagnetic waves as a result of relativistic electron-mass variation
International Nuclear Information System (INIS)
Spatschek, K.H.
1977-01-01
Relativistic electron-mass variations due to the presence of intense electromagnetic radiation in the plasma cause a nonlinear refractive index. Using a variational principle the latter is obtained up to fourth order in the electric field amplitude and it is shown that nonlinear effects of the second order lead to self-focusing of a beam of radiation. By nonlinear optics considerations, the self-focusing length of an axially symmetric beam is obtained. Including higher-order dispersive effects it is shown that within the thin-beam approximation the complex electric field envelope obeys a cubic nonlinear Schroedinger equation with an attractive self-consistent potential. The cylindrically symmetric nonlinear Schroedinger equation predicts collapse of the radiation at the self-focusing distance. The nature of the self-focusing singularity is analysed and it is shown that higher-order nonlinearities saturate the amplitude. Then oscillations of the beam radius along the axial direction occur. (author)
Design study of primary ion provider for relativistic heavy ion collider electron beam ion source.
Kondo, K; Kanesue, T; Tamura, J; Okamura, M
2010-02-01
Brookhaven National Laboratory has developed the new preinjector system, electron beam ion source (EBIS) for relativistic heavy ion collider (RHIC) and National Aeronautics and Space Administration Space Radiation Laboratory. Design of primary ion provider is an essential problem since it is required to supply beams with different ion species to multiple users simultaneously. The laser ion source with a defocused laser can provide a low charge state and low emittance ion beam, and is a candidate for the primary ion source for RHIC-EBIS. We show a suitable design with appropriate drift length and solenoid, which helps to keep sufficient total charge number with longer pulse length. The whole design of primary ion source, as well as optics arrangement, solid targets configuration and heating about target, is presented.
Technological Aspects of Corrosion-Resistant Steels Surfacing by Intense Relativistic Electron Beams
Belozerov, V. V.; Donets, S. E.; Klepikov, V. F.; Kivshik, V. F.; Lytvynenko, V. V.; Lonin, Yu. F.; Ponomarev, A. G.; Uvarov, V. T.
Intense tubular relativistic electron beams are a promising tool for a number of practical applications, such as obtaining nanodispersed powder materials, surface properties modification of products, remote surfacing, etc. In current technologies for obtaining of nanopowder materials, one of the leading techniques is one based on the materials handling concentrated flows of energy. Using the various technological equipment (pulse current generators, accelerators), energy is inputted into the material in the form of intense impulse current, the plasma flows of charged particle beams. Each of the specified types of impact is characterized by a certain decomposition mechanism of processed materials to micro- and nano-sized state. Thus, the action of intense pulsed currents based on the thermal evaporation of a melt conductor with its subsequent condensation in liquid, the use of plasma flows and charged particle beams also involves evaporation and condensation of a material in a vacuum or in a special atmosphere.
Anisotropic metamaterial waveguide driven by a cold and relativistic electron beam
Torabi, Mahmoud; Shokri, Babak
2018-03-01
We study the interaction of a cold and relativistic electron beam with a cylindrical waveguide loaded by an anisotropic and dispersive metamaterial layer. The general dispersion relation for the transverse magnetic (TM) mode, through the linear fluid model and Maxwell equations decomposition method, is derived. The effects of some metamaterial parameters on dispersion relation are presented. A qualitative discussion shows the possibility of monomodal propagation band widening and obtaining more control on dispersion relation behavior. Especially for epsilon negative near zero metamaterials, these effects are considerable. Finally, the anisotropy and metamaterial layer thickness impacts on wave growth rate for different metamaterials are considered. The results demonstrate that we can control both wave growth rate and voltage of saturation peak by metamaterial parameters.
Interaction of an intense relativistic electron beam with full density air
International Nuclear Information System (INIS)
Murphy, D.P.; Pechacek, R.E.; Raleigh, M.; Oliphant, W.F.; Meger, R.A.
1987-01-01
The authors report on a study of plasma generation by direct deposition of energy from an intense relativistic electron beam (REB) into full density air. It has been postulated that a sufficiently intense REB can fully ionize the air and produce a 2 eV plasma with Spitzer conductivity. The REB is produced from a field emission diode driven by either the Gamble I or Gamble II generator. Gamble I can produce a 0.60 MV, 300 kA, 50 ns REB and Gamble II can produce a 2.0 MV, 1.0 MA, 50 ns REB. The REB was injected into a short diagnostic cell containing full density air and up to a 14 kG solenoidal magnetic field. The diagnostics include beam and net current measurements, x-ray and visible photography and visible light spectroscopy
System for detecting neutrons in the harsh radiation environment of a relativistic electron beam
International Nuclear Information System (INIS)
Kruse, L.W.
1978-06-01
Newly developed detectors and procedures allow measurement of neutron yield and energy in the harsh radiation environment of a relativistic electron beam source. A new photomultiplier tube design and special gating methods provide the basis for novel time-of-flight and total-yield detectors. The technique of activation analysis is expanded to provide a neutron energy spectrometer. There is a demonstrated potential in the use of the integrated system as a valuable diagnostic tool to study particle-beam fusion, intense ion-beam interactions, and pulsed neutron sources for simulating weapons effects. A physical lower limit of 10 8 neutrons into 4π is established for accurate and meaningful measurements in the REB environment
Martinez-Consentino, V. L.; Ruiz Simo, I.; Amaro, J. E.; Ruiz Arriola, E.
2017-12-01
The relativistic effective mass M* and Fermi momentum kF are important ingredients in the determination of the nuclear equation of state, but they have rarely been extracted from experimental data below saturation density where translationally invariant nuclear matter becomes unstable against clusterization into the existing atomic nuclei. Using a novel kind of superscaling analysis of the quasielastic cross-section electron scattering data involving a suitable selection criterion and 12C as a reference nucleus, the global scaling properties of the resulting set of data for 21 nuclei ranging from 2H to 238U are then analyzed. We find that a subset of a third of the about 20000 data approximately scales to an universal superscaling function with a more constrained uncertainty band than just the reference 12C case and provides M* as a function of kF.
International Nuclear Information System (INIS)
2016-01-01
These Proceedings are published as a recollection of contributions presented at the XI International Symposium on “Radiation from Relativistic Electrons in Periodic Structures” (RREPS-15), which was held in Saint Petersburg, September 6-11, 2015, Russian Federation. RREPS-15 was co-organized by Saint-Petersburg State University, National Research Tomsk Polytechnic University, and National Research Nuclear University (MEPhI). The main goal of the symposium was to bring together the scientists from around the world who work on designs of new radiation sources and their applications. There were 108 participants registered from 12 countries. The website of the symposium is available at http://rreps.tpu.ru/. (paper)
The infrared problem for the dressed non-relativistic electron in a magnetic field
International Nuclear Information System (INIS)
Amour, L.; Faupin, J.; Grebert, B.; Guillot, J.C.
2008-01-01
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x 3 -axis and with a quantized electromagnetic field. The system is translation invariant in the x 3 -direction and the corresponding Hamiltonian has a decomposition H ≅∫ R + H(P 3 )dP 3 . For a fixed momentum P 3 sufficiently small, we prove that H(P 3 ) has a ground state in the Fock representation if and only if E'(P 3 )=0, where P 3 →E'(P 3 ) is the derivative of the map P 3 →E(P 3 )=infσ(H(P 3 )). If E'(P 3 )≠0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Atmospheric Signatures and Effects of Space-based Relativistic Electron Beam Injection
Marshall, R. A.; Sanchez, E. R.; Kero, A.; Turunen, E. S.; Marsh, D. R.
2017-12-01
Future relativistic electron beam injection experiments have the potential to provide groundbreaking insights into the physics of wave-particle interactions and beam-neutral interactions, relevant to space physics and to fundamental plasma physics. However, these experiments are only useful if their signatures can be detected. In this work, we use a physics-based forward modeling framework to investigate the observable signatures of a relativistic beam interacting with the upper atmosphere. The modeling framework is based around the Electron Precipitation Monte Carlo (EPMC) model, used to simulate electron precipitation in the upper atmosphere. That model is coupled to physics-based models of i) optical emission production; ii) bremsstrahlung photon production and propagation; iii) D-region ion chemistry; and iv) VLF wave propagation in the Earth-ionosphere waveguide. Using these modeling tools, we predict the optical, X-ray, chemical, radar, and VLF signatures of a realistic beam injection, based on recent space-based accelerator designs. In particular, we inject a beam pulse of 10 mA for a duration of 500 μs at an energy of 1 MeV, providing a total pulse energy of 5 J. We further investigate variations in these parameters, in particular the total energy and the electron energy. Our modeling shows that for this 5 J pulse injection at 1 MeV electron energy, the optical signal is easily detectable from the ground in common emission bands, but the X-ray signal is likely too weak to be seen from either balloons or LEO orbiting spacecraft. We further predict the optical signal-to-noise ratio that would be expected in different optical systems. Chemical signatures such as changes to NOx and HOx concentrations are too short-lived to be detectable; however our modeling provides a valuable estimate of the total chemical response. Electron density perturbations should be easily measurable from ground-based high-power radars and via VLF subionospheric remote sensing
Dachev, Tsvetan
Relativistic electron precipitation (REP) are observed by the R3D B2/B3 and RD3-B3 instruments during the flights of the Foton M2/M3 and “BION-M” 1 satellite in 2005, 2007 and 2013, and by the R3DE/R instruments at the EXPOSE-E facility of the European Columbus module and at the EXPOSE-R facility of the Russian Zvezda module of the International Space Station (ISS) in the period from February 2008 till August 2010. The obtained dose rates strongly depend by the external and internal shielding of the detectors in the instruments. The highest dose rate reaching more than 20 mGy h (-1) was observed outside the ISS Zvezda module during the REP in April 2010 being the second largest in GOES history with a >2 MeV electron fluence event. REP doses behind relatively thick shielding are too small but may play considerable role during extra vehicular activity (EVA) when the cosmonauts/astronauts body is shielded only by the space suit.
Salmanpoor, H.; Sharifian, M.; Gholipour, S.; Borhani Zarandi, M.; Shokri, B.
2018-03-01
The oblique propagation of nonlinear ion acoustic solitary waves (solitons) in magnetized collisionless and weakly relativistic plasma with positive and negative ions and super thermal electrons has been examined by using reduced perturbation method to obtain the Korteweg-de Vries equation that admits an obliquely propagating soliton solution. We have investigated the effects of plasma parameters like negative ion density, electrons temperature, angle between wave vector and magnetic field, ions velocity, and k (spectral index in kappa distribution) on the amplitude and width of solitary waves. It has been found out that four modes exist in our plasma model, but the analysis of the results showed that only two types of ion acoustic modes (fast and slow) exist in the plasma and in special cases only one mode could be propagated. The parameters of plasma for these two modes (or one mode) determine which one is rarefactive and which one is compressive. The main parameter is negative ions density (β) indicating which mode is compressive or rarefactive. The effects of the other plasma parameters on amplitude and width of the ion acoustic solitary waves have been studied. The main conclusion is that the effects of the plasma parameters on amplitude and width of the solitary wave strongly depend on the value of the negative ion density.
1994-01-01
The NATO Advanced Study Institute (ASI) on "R@lativistic and Electron Correlation Effects in Molecules and Solids", co-sponsored by Simon Fraser University (SFU) and the Natural Sciences and Engineering Research Council of Canada (NSERC) was held Aug 10- 21, 1992 at the University of British Columbia (UBC), Vancouver, Canada. A total of 90 lecturers and students with backgrounds in Chemistry, Physics, Mathematics and various interdisciplinary subjects attended the ASI. In my proposal submitted to NATO for financial support for this ASI, I pointed out that a NATO ASI on the effects of relativity in many-electron systems was held ten years ago, [See G.L. Malli, (ed) Relativistic Effects in Atoms, Molecules and Solids, Plenum Press, Vol B87, New York, 1983]. Moreover, at a NATO Advanced Research Workshop (ARW) on advanced methods for molecular electronic structure "an assessment of state-of the-art of Electron Correlation ... " was carried out [see C.E. Dykstra, (ed), Advanced Theories and Computational Approa...
Nonlinear bound on unstable field energy in relativistic electron beams and plasmas
International Nuclear Information System (INIS)
Davidson, R.C.; Yoon, P.H.
1989-01-01
This paper makes use of Fowler's method [J. Math Phys. 4, 559 (1963)] to determine the nonlinear thermodynamic bound on field energy in unstable plasmas or electron beams in which the electrons are relativistic. Treating the electrons as the only active plasma component, the nonlinear Vlasov--Maxwell equations and the associated global conservation constraints are used to calculate the lowest upper bound on the field energy [ΔE-script/sub F/]/sub max/ that can evolve for the general initial electron distribution function f/sub b//sub / 0 equivalentf/sub b/(x,p,0). The results are applied to three choices of the initial distribution function f/sub b//sub / 0 . Two of the distribution functions have an inverted population in momentum p/sub perpendicular/ perpendicular to the magnetic field B 0 e/sub z/, and the third distribution function reduces to a bi-Maxwellian in the nonrelativistic limit. The lowest upper bound on the efficiency of radiation generation, eta/sub max/ = [ΔE-script/sub F/]/sub max//[V -1 ∫ d 3 x∫ d 3 p(γ-1)mc 2 f/sub b//sub / 0 ], is calculated numerically over a wide range of system parameters for varying degrees of initial anisotropy
Novel probe for determining the size and position of a relativistic electron beam
International Nuclear Information System (INIS)
Orzechowski, T.J.; Koehler, H.; Edwards, W.; Nelson, M.; Marshall, B.
1984-01-01
In order to determine the size and position of a relativistic electron beam inside the wiggler magnetic field of a Free Electron Laser (FEL), we have developed a new probe which intercepts the electron beam on a high Z target and monitors the resulting bremsstrahlung radiation. The probe is designed to move along the entire three meters of the wiggler. This FEL is designed to operate in the microwave region (2 to 8 mm) and the interaction region is an oversized waveguide with a cross section 3 cm x 9.8 cm. The axial probe moves inside this waveguide. The probe stops the electron beam on a Tantalum target and the resulting x-rays are scattered in the forward direction. A scintillator behind the beam stop reacts to the x-rays and emits visible light in the region where the x-rays strike. An array of fiber optics behind the scintillator transmits the visible light to a Reticon camera system which images the visible pattern from the scintillator. Processing the optical image is done by digitizing and storing the image and/or recording the image on video tape. Resolution and performance of this probe will be discussed
International Nuclear Information System (INIS)
Pupasov-Maksimov, Andrey; Deriglazov, Alexei
2012-01-01
Full text: We consider a classical model of the relativistic electron proposed by A. Deriglazov in Phys. Lett. A 376 (2012) 309-313. Though this model contains only bosonic variables, its quantization leads to the Dirac equation and one-particle relativistic quantum mechanics of the electron. There are constraints and gauge symmetries, therefore 18 initial variables of the model {x μ , p μ , ω A , π A }, μ is an element of (0,4), A is an element of (0,5) do not correspond to the observable quantities. There are 10 physical degrees of freedom implying another set of 10 gauge invariant variables which will be interpreted as physically observable quantities. On the other hand, to have a consistent one-particle relativistic quantum mechanics one has to consider only even operators which do not mix quantum states with positive and negative energy states. Such separation can be obtained with the Foldy-Wouthuysen transformation and leads to the Foldy-Wouthuysen representation with new operators for coordinates and spin (so-called Newton-Wigner coordinates). In the present work we match these to pictures by comparing the choice of the gauge invariant classical variables and the transition to the even operators in the quantum mechanics. We study different canonical transformations of this classical model in order to separate the set of observable quantities from variables with ambiguous dynamics. The constraints of the model in the case of free particle can be chosen in such a way that the Dirac brackets coincide with the Poisson brackets. This choice significantly simplify calculations of transformed variables. Moreover, new variables are canonical variables by construction. It is shown that the following generator of an infinitesimal canonical transformation S=1/2J 5j p j A(p 2 ), can be associated with the Foldy-Wouthuysen transformation. Thus we obtain a classical analog of the Foldy- Wouthuysen transformation. Moreover, the gauge invariant variables in the
Relativistic and correlation effects in electron impact excitation of forbidden transitions of OII
International Nuclear Information System (INIS)
Montenegro, Maximiliano; Eissner, Werner; Nahar, Sultana N; Pradhan, Anil K
2006-01-01
We investigate relativistic and correlation effects in electron impact excitation of singly ionized oxygen using the Breit-Pauli R-matrix method. The intermediate coupling close-coupling calculations are carried out using a 16-level target representation dominated by the electronic configurations 1s 2 2s 2 2p 3 , 1s 2 2s2p 4 , 1s 2 2s 2 2p 2 3s. Resonance structures are delineated in detail to ascertain the effect on averaged collision strengths. Convergence of the partial wave summation is ensured for non-dipole transitions in the R-matrix calculations. The present results differ significantly from the similar Breit-Pauli R-matrix calculations by McLaughlin and Bell (1998 J. Phys. B: At. Mol. Opt. Phys. 31 4317-29), but are essentially in agreement with the LS coupling results of Pradhan (1976a J. Phys. B: At. Mol. Opt. Phys. 9 433-43, 1976b Mon. Not. R. Astron. Soc. 177 31-8). A comprehensive study of the detailed energy behaviour of all forbidden transitions among the five levels of the ground configuration, i.e. 2s2p 3 ( 4 S o 3/2 , 2 D o 5/2,3/2 , 2 P o 3/2,1/2 ) shows that the finestructure collision strengths do not significantly depart from the values obtained from a purely LS → LSJ transformation, and relativistic effects are therefore small. We find that the Maxwellian-averaged effective collision strengths for the ten transitions also differ from the previous work, most likely due to more extensive delineation of resonances in the present work. However, the differences are largely systematic and therefore the OII line intensity ratios are not significantly affected. We also obtain an excellent agreement between the present-calculated cross sections for the 4 S o - 2 D o transition and the experimental merged beam measurements
Kolesnikov, E. K.; Manuilov, A. S.; Petrov, V. S.
2018-01-01
We have analyzed the tacking force exerted by a low-conductivity Ohmic plasma channel on a relativistic electron beam. It has been shown that, for the given type of evolution of the resistive hose instability of the beam along its pulse, this force substantially depends on the frequency and the increment of the increase in the given instability.
Tulupov, A. V.
1993-01-01
A comparison of the spectral-angular intensity of radiation of a relativistic electron beam is carried oui in the X-ray range for different radiation types: transition radiation: parametric Cherenkov radiation; undulattor radiation: and radiation in the electromagnetic wave field. Simple analytical
Ultra-High-Contrast Laser Acceleration of Relativistic Electrons in Solid Targets
Energy Technology Data Exchange (ETDEWEB)
Higginson, Drew Pitney [Univ. of California, San Diego, CA (United States)
2013-01-01
The cone-guided fast ignition approach to Inertial Con nement Fusion requires laser-accelerated relativistic electrons to deposit kilojoules of energy within an imploded fuel core to initiate fusion burn. One obstacle to coupling electron energy into the core is the ablation of material, known as preplasma, by laser energy proceeding nanoseconds prior to the main pulse. This causes the laser-absorption surface to be pushed back hundreds of microns from the initial target surface; thus increasing the distance that electrons must travel to reach the imploded core. Previous experiments have shown an order of magnitude decrease in coupling into surrogate targets when intentionally increasing the amount of preplasma. Additionally, for electrons to deposit energy within the core, they should have kinetic energies on the order of a few MeV, as less energetic electrons will be stopped prior to the core and more energetic electrons will pass through the core without depositing much energy. Thus a quantitative understanding of the electron energy spectrum and how it responds to varied laser parameters is paramount for fast ignition. For the rst time, this dissertation quantitatively investigates the acceleration of electrons using an ultra-high-contrast laser. Ultra-high-contrast lasers reduce the laser energy that reaches the target prior to the main pulse; drastically reducing the amount of preplasma. Experiments were performed in a cone-wire geometry relevant to fast ignition. These experiments irradiated the inner-tip of a Au cone with the laser and observed electrons that passed through a Cu wire attached to the outer-tip of the cone. The total emission of K x-rays is used as a diagnostic to infer the electron energy coupled into the wire. Imaging the x-ray emission allowed an e ective path-length of electrons within the wire to be determined, which constrained the electron energy spectrum. Experiments were carried out on the ultra-high-contrast Trident laser at Los
International Nuclear Information System (INIS)
Tang, C. L.; Wang, Y. X.; Ni, B.; Zhang, J.-C.
2017-01-01
Using the Van Allen Probes data, we study the radiation belt seed population and it associated with the relativistic electron dynamics during 74 geomagnetic storm events. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of “non-preconditioned” and “preconditioned”. The statistical study shows that the storm intensity is of significant importance for the distribution of the seed population (336 keV electrons) in the outer radiation belt. However, substorm intensity can also be important to the evolution of the seed population for some geomagnetic storm events. For non-preconditioned storm events, the correlation between the peak fluxes and their L-shell locations of the seed population and relativistic electrons (592 keV, 1.0 MeV, 1.8 MeV, and 2.1 MeV) is consistent with the energy-dependent dynamic processes in the outer radiation belt. For preconditioned storm events, the correlation between the features of the seed population and relativistic electrons is not fully consistent with the energy-dependent processes. It is suggested that the good correlation between the radiation belt seed population and ≤1.0 MeV electrons contributes to the prediction of the evolution of ≤1.0 MeV electrons in the Earth’s outer radiation belt during periods of geomagnetic storms.
Willard, J.; Johnson, J.; Sanchez, E. R.; Kaganovich, I.; Greklek-McKeon, M.; Powis, T.
2017-12-01
New accelerator technologies have made it possible to install a lightweight electron beam accelerator onto small to medium satellites. Electron beams fired along the geomagnetic field would be able to carry energy flux into the ionosphere if they were fired into the loss cone, making these particles observable from the ground. Such an experiment would provide a way to accurately map field lines. One of the important challenges to utilizing this concept is understanding accessibility of these electrons to the ionosphere. While relativistic electron beams are generally more stable than lower energy beams, they are more sensitive to the effects of field-line curvature, which can significantly modify the loss cone [Porazik et al., 2014] making accessibility to the ionosphere sensitive to the launch angle with respect to the magnetic field. We examine the loss cone for 1 MeV electrons in a realistic magnetospheric geometry considering, in particular, the role of field-line stretching. To map the loss cone, we consider conservation of the first adiabatic invariant to second order in ρ/L using the asymptotic series derived by Gardner [Phys Fluids, 1966], which is valid on the midnight meridian. We investigate the loss cones for different magnetic field models controlled by a stretching parameter over the entire midnight meridian. We found that, because tail stretching increases field line curvature near the midplane but decreases curvature elsewhere, accessibility to the ionosphere is increased by tail stretching in regions above and below the midplane, although accessibility of particles passing through the midplane is reduced. This result implies that satellites armed with electron beam accelerators may be able to visibly affect the atmosphere from distances greater than previously anticipated.
Transverse phase space mapping of relativistic electron beams using optical transition radiation
Directory of Open Access Journals (Sweden)
G. P. Le Sage
1999-12-01
Full Text Available Optical transition radiation (OTR has proven to be a versatile and effective diagnostic for measuring the profile, divergence, and emittance of relativistic electron beams with a wide range of parameters. Diagnosis of the divergence of modern high brightness beams is especially well suited to OTR interference (OTRI techniques, where multiple dielectric or metal foils are used to generate a spatially coherent interference pattern. Theoretical analysis of measured OTR and OTRI patterns allows precise measurement of electron beam emittance characteristics. Here we describe an extension of this technique to allow mapping of divergence characteristics as a function of transverse coordinates within a measured beam. We present the first experimental analysis of the transverse phase space of an electron beam using all optical techniques. Comparing an optically masked portion of the beam to the entire beam, we measure different angular spread and average direction of the particles. Direct measurement of the phase-space ellipse tilt angle has been demonstrated using this optical masking technique.
Energy Technology Data Exchange (ETDEWEB)
Ahmad, Ali [National Centre for Physics, Shahdara Valley Road, Islamabad (Pakistan); Masood, W. [National Centre for Physics, Shahdara Valley Road, Islamabad (Pakistan); COMSATS Institute of Information Technology, Park Road, Chak Shahzad, Islamabad (Pakistan)
2016-05-15
Linear and nonlinear electrostatic ion acoustic waves in a weakly relativistic magnetorotating plasma in the presence of non-Maxwellian electrons and warm ions have been examined. The system under consideration has yielded two solutions, namely, the fast and slow acoustic modes which have been observed to depend on the streaming velocity, ion to electron temperature ratio, and the nonthermality parameter of the non-Maxwellian electrons. Using the multiple time scale analysis, we have derived the three dimensional nonlinear Zakharov–Kuznetsov equation and also presented its solution. Both compressive and rarefactive solitary structures have been found in consonance with the satellite observations. It has been observed that although the linear dispersion relation gives both fast and slow ion acoustic waves, the solitary structures form only for the fast acoustic mode. The dependence of the characteristics of the solitary structures on several plasma parameters has also been explored. The present investigation may be beneficial to understanding the rotating plasma environments such as those found in the planetary magnetospheres of Saturn and Jupiter.
Interaction of a relativistic electron beam with radiation in the THz frequency range
Sung, Chieh
The ability to generate a train of microbunches that are only typically tens of femtosecond wide and are separated by a picosecond is a topic of contemporary interest in the field of free electron lasers and plasma based accelerators. Moreover the usefulness of the high gradients present in plasma accelerators will depend on the ability to obtain mono-energetic relativistic electrons. This means that in addition to being prebunched on a scale shorter than the plasma wavelength the externally injected electron beam must be phase-locked to the accelerating plasma wave structure. In this thesis we investigate two techniques, Free Electron Laser interaction (FEL) and the Inverse Free Electron Laser interaction (IFEL), by which a medium energy electron beam can be prebunched into a series of microbunches with the same periodicity as a plasma wave and is phase locked to it. Using full-scale, 3-D simulations we show in this thesis that when a relativistic electron beam and an electromagnetic wave propagate collinearly through a magnetic undulator, FEL and IFEL interactions have the capability to form electron microbunches with periodicity 300-100 mum (1-3 THz range), which contain 50% of electrons within a small fraction of the ponderomotive buckets. Such a bunched beam is suitable for injection into plasma densities in the range 1016-1017 cm-3, respectively. Microbunching using the FEL mechanism requires a narrowband THz radiation source to act as a seed whereas the IFEL mechanism requires, in addition, such a source to be high power. In this thesis the generation of THz radiation in the Neptune Laboratory by mixing of two CO2 laser lines in a non-collinearly phase matched GaAs at room temperature is described A high-power THz pulse with up to 2 MW of peak power in a 250 ps pulse was generated using a TW class CO2 laser pulse. Such high power THz radiation is needed for the IFEL approach to microbunching. We also produced a high repetition rate THz source tunable in the
Strongly correlated electron materials. I. Theory of the quasiparticle structure
Energy Technology Data Exchange (ETDEWEB)
Lopez-Aguilar, F.; Costa-Quintana, J.; Puig-Puig, L. (Departamento de Fisica, Grupo de Electromagnetismo, Universidad Autonoma de Barcelona, Bellaterra, E-08193 Barcelona (Spain))
1993-07-01
In this paper we give a method for analyzing the renormalized electronic structure of the Hubbard systems. The first step is the determination of effective interactions from the random-phase approximation (RPA) and from an extended RPA (ERPA) that introduces vertex effects within the bubble polarization. The second step is the determination of the density of states deduced from the spectral functions. Its analysis leads us to conclude that these systems can exhibit three types of resonances in their electronic structures: the lower-, middle-, and upper-energy resonances. Furthermore, we analyze the conditions for which there is only one type of resonance and the causes that lead to the disappearance of the heavy-fermion state. We finally introduce the RPA and ERPA effective interactions within the strong-coupling theory and we give the conditions for obtaining coupling and superconductivity.
Bound states in strongly correlated magnetic and electronic systems
International Nuclear Information System (INIS)
Trebst, S.
2002-02-01
A novel strong coupling expansion method to calculate two-particle spectra of quantum lattice models is developed. The technique can be used to study bosonic and fermionic models and in principle it can be applied to systems in any dimension. A number of strongly correlated magnetic and electronic systems are examined including the two-leg spin-half Heisenberg ladder, the dimerized Heisenberg chain with a frustrating next-nearest neighbor interaction, coupled Heisenberg ladders, and the one-dimensional Kondo lattice model. In the various models distinct bound states are found below the two-particle continuum. Quantitative calculations of the dispersion, coherence length and binding energy of these bound states are used to describe spectroscopic experiments on (Ca,La) 14 Cu 24 O 41 and NaV 2 O 5 . (orig.)
Correlated electron-ion collisions in a strong laser field
International Nuclear Information System (INIS)
Ristow, T.
2007-01-01
Electron-ion-collisions in plasmas in the presence of an ultra-short intensive laser pulse can cause high energy transfers to the electrons. During the collision the oscillation energy of the electron in the laser field is changed into drift energy. In this regime, multi-photon processes, known from the ionization of neutral atoms (Above-Threshold Ionization), and successive, so called correlated collisions, are important. The subject of the thesis is a study of binary Coulomb collisions in strong laser fields. The collisions are treated both in the context of classical Newtonian mechanics and in the quantum-mechanical framework by the Schroedinger equation. In the classical case a simplified instantaneous collision model and a complete dynamical treatment are discussed. Collisions can be treated instantaneously, if the ratio of the impact parameter to the quiver amplitude is small. The energy distributions calculated in this approximation show an elastic peak and a broad plateau due to rescattered electrons. At incident velocities smaller than the quiver velocity, correlated collisions are observed in the electron trajectories of the dynamical model. This effect leads to characteristic momentum distributions of the electrons, that are explicitly calculated and compared with the results of the instantaneous model. In addition, the time-dependence of the collisions is discussed in the framework of a singular perturbation theory. The complete description of the Coulomb scattering requires a quantum-mechanical description. A time-dependent method of wave-packet scattering is used and the corresponding time-dependent three-dimensional Schroedinger equation is solved by an implicit ADImethod on a spatial grid. The momentum and the energy distributions of the scattered electrons are calculated by the Fourier transformation of the wavefunction. A comparison of the scattering from a repulsive and an attractive potential is used to distinguish between simple collisions and
Drozdov, A. Y.; Shprits, Y. Y.; Orlova, K. G.; Kellerman, A. C.; Subbotin, D. A.; Baker, D. N.; Spence, H. E.; Reeves, G. D.
2015-05-01
In this study, we compare long-term simulations performed by the Versatile Electron Radiation Belt (VERB) code with observations from the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope instruments on the Van Allen Probes satellites. The model takes into account radial, energy, pitch angle and mixed diffusion, losses into the atmosphere, and magnetopause shadowing. We consider the energetic (>100 keV), relativistic (~0.5-1 MeV), and ultrarelativistic (>2 MeV) electrons. One year of relativistic electron measurements (μ = 700 MeV/G) from 1 October 2012 to 1 October 2013 are well reproduced by the simulation during varying levels of geomagnetic activity. However, for ultrarelativistic energies (μ = 3500 MeV/G), the VERB code simulation overestimates electron fluxes and phase space density. These results indicate that an additional loss mechanism is operational and efficient for these high energies. The most likely mechanism for explaining the observed loss at ultrarelativistic energies is scattering by the electromagnetic ion cyclotron waves.
Strongly Coupled Magnetic and Electronic Transitions in Multivalent Strontium Cobaltites.
Lee, J H; Choi, Woo Seok; Jeen, H; Lee, H-J; Seo, J H; Nam, J; Yeom, M S; Lee, H N
2017-11-22
The topotactic phase transition in SrCoO x (x = 2.5-3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO 2.5 that is a room-temperature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO 3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO 2.5 , however, it has been conjectured that the magnetic transition is decoupled to the electronic phase transition, i.e., the AFM-to-FM transition occurs before the insulator-to-metal transition (IMT), which is still controversial. Here, we bridge the gap between the two-phase transitions by density-functional theory calculations combined with optical spectroscopy. We confirm that the IMT actually occurs concomitantly with the FM transition near the oxygen content x = 2.75. Strong charge-spin coupling drives the concurrent IMT and AFM-to-FM transition, which fosters the near room-T magnetic transition characteristic. Ultimately, our study demonstrates that SrCoO x is an intriguingly rare candidate for inducing coupled magnetic and electronic transition via fast and reversible redox reactions.
Hoefener, S.; Ahlrichs, R.; Knecht, S.; Visscher, L.
2012-01-01
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga
Nearly relativistic electron fluxes and ionospheric parameters as components of space weather
Dudnik, Oleksiy; Rothkaehl, Hanna; Matyjasiak, Barbara
2017-04-01
We present specific features detected in spatial distributions of magnetospheric high energy electrons and in ionosphere plasma electron densities and temperatures during a deep minimum of 11 year's cycle of solar activity. New outcome comes as a result of joint analysis of experimental data derived from the satellite telescope of electrons and protons STEP-F aboard the low, circular and highly inclined orbit CORONAS-Photon satellite, and from Demeter satellite. The highly sensitive STEP-F instrument flown in 2009 and measured sub-relativistic electron fluxes and protons of intermediate energies by extensive-angled telescopic system of detectors at the height of 550 km covering the wide range of McIlwain L-parameters from 1 up to 20. We present peculiar characteristics of electron flows in well-known Van Allen outer and inner radiation belts, inside the region of South Atlantic Anomaly and outside of mentioned zones observed during the first half of May, 2009. In spite of extremely low solar activity, and the presence of single geomagnetic substorm on May, 6-8, which was characterized by remarkably small Dst =-30 nT, substantial variations of electron fluxes with energies E > 180 keV came into being in all zones of enhanced charge radiation. It was clearly seen elongation of the South Atlantic Anomaly in terms of electron flows up to low and near-equatorial latitudes to eastern-directed longitudes. Throughout the whole period there were recorded two radiation belts in the inner magnetosphere: well-studied at L 2.3, and additional one at L 1.6. The third radiation belt at L 1.6 had specific belt-shaped profile of particle fluxes, and registered at broad range of longitudes that do not coincide with those ones related to the Anomaly location. The analyses of subrelativistic electrons at the heights of upper ionosphere and inospheric plasma parameters has been analysed. From this standpoint we consider electron flux pulsations during various phases of geomagnetic
Strongly correlated electron physics in nanotube-encapsulated metallocene chains
García-Suárez, V. M.; Ferrer, J.; Lambert, C. J.
2006-11-01
The structural, electronic, and transport properties of metallocene molecules (MCp2) and isolated or nanotube-encapsulated metallocene chains are studied by using a combination of density functional theory and nonequilibrium Green’s functions. The analysis first discusses the whole series of isolated (MCp2) molecules, where M=V , Cr, Mn, Fe, Co, Ni, Ru, and Os. The series presents a rich range of electronic and magnetic behaviors due to the interplay between the crystal field interaction and Hund’s rules, as the occupation of the d shell increases. The article then shows how many of these interesting properties can also be seen when (MCp2) molecules are linked together to form periodic chains. Interestingly, a large portion of these chains display metallic, and eventually magnetic, behavior. These properties may render these systems as useful tools for spintronics applications but this is hindered by the lack of mechanical stability of the chains. It is finally argued that encapsulation of the chains inside carbon nanotubes, that is exothermic for radii larger than 4.5Å , provides the missing mechanical stability and electrical isolation. The structural stability, charge transfer, magnetic, and electronic behavior of the ensuing chains, as well as the modification of the electrostatic potential in the nanotube wall produced by the metallocenes are thoroughly discussed. We argue that the full devices can be characterized by two doped, strongly correlated Hubbard models whose mutual hybridization is almost negligible. The charge transferred from the chains produces a strong modification of the electrostatic potential in the nanotube walls, which is amplified in case of semiconducting and endothermic nanotubes. The transport properties of isolated metallocenes between semi-infinite nanotubes are also analyzed and shown to lead to important changes in the transmission coefficients of clean nanotubes for high energies.
Relativistic attosecond electron bunch emission from few-cycle laser irradiated nanoscale droplets
Directory of Open Access Journals (Sweden)
Laura Di Lucchio
2015-02-01
Full Text Available Attosecond electron bunches produced at the surface of nanometer-scale droplets illuminated by a two-cycle laser pulse are investigated for the purpose of determining their optimal emission characteristics. Significant departures from Mie theory are found for electron bunch emission from droplets whose radii satisfy the condition δ_{r}
Electromagnetic computer simulations of collective ion acceleration by a relativistic electron beam
International Nuclear Information System (INIS)
Galvez, M.; Gisler, G.R.
1988-01-01
A 2.5 electromagnetic particle-in-cell computer code is used to study the collective ion acceleration when a relativistic electron beam is injected into a drift tube partially filled with cold neutral plasma. The simulations of this system reveals that the ions are subject to electrostatic acceleration by an electrostatic potential that forms behind the head of the beam. This electrostatic potential develops soon after the beam is injected into the drift tube, drifts with the beam, and eventually settles to a fixed position. At later times, this electrostatic potential becomes a virtual cathode. When the permanent position of the electrostatic potential is at the edge of the plasma or further up, then ions are accelerated forward and a unidirectional ion flow is obtained otherwise a bidirectional ion flow occurs. The ions that achieve higher energy are those which drift with the negative potential. When the plasma density is varied, the simulations show that optimum acceleration occurs when the density ratio between the beam (n b ) and the plasma (n o ) is unity. Simulations were carried out by changing the ion mass. The results of these simulations corroborate the hypothesis that the ion acceleration mechanism is purely electrostatic, so that the ion acceleration depends inversely on the charge particle mass. The simulations also show that the ion maximum energy increased logarithmically with the electron beam energy and proportional with the beam current
VISSCHER, L; SAUE, T; NIEUWPOORT, WC; FAEGRI, K; GROPEN, O
1993-01-01
Fully relativistic all-electron self-consistent field calculations based on the Dirac-Coulomb Hamiltonian have been performed on the three lowest lying states of the PtH molecule. The resulting four-component Dirac-Hartree-Fock (DHF) molecular spinors are subsequently used in relativistic
Schiller, Q.; Kanekal, S. G.; Jian, L. K.; Li, X.; Jones, A.; Baker, D. N.; Jaynes, A.; Spence, H. E.
2016-12-01
We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E > 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated with MeV electron depletion. Parameters that represent IP shock strength are found to correlate best with highest levels of energization, suggesting that shock strength may play a key role in the severity of the enhancements. However, not every shock results in an enhancement, indicating that magnetospheric preconditioning may be required.
International Nuclear Information System (INIS)
Panasyuk, M.I.; Svertilov, S.I.; Bogomolov, V.V.; Garipov, G.K.; Bogomolov, E.A. A.V.; Myagkova, I.N.; Klimov, P.A.; Prokhorov, A.V.; Klimov, S.I.; Grechko, T.V.; Grushin, V.A.; Vavilov, D.I.; Korepanov, V.E.; Belyaev, S.V.; Demidov, A.N.; Ferencz, Cs.; Bodnár, L.; Szegedi, P.; Rothkaehl, H.; Moravski, M.
2016-01-01
Experiment “RELEC” on-board satellite Vernov, launched July 2014, contains a suite of scientific instruments including gamma-spectrometer (0.01-3.0 MeV), spectrometer of electrons (0.2-15.0 MeV), UV (300-400 nm) and optic sl (600--800 nm) photometer and imager, radio wave low frequency (0.001 - 40.0 kHz) and high frequency (0.05 - 15.0 MHz) analyzers. Gamma and electron spectrometers were used to study transient events, including terrestrial gamma-flashes (TGFs) and precipitations of relativistic electrons from the Earth magnetosphere with ~15 mcs time resolution. Comparative correlating analysis of the data taken by the on-board instruments were made. First catalogue of TGFs detected by “RELEC” during is presented. Events that are included in this catalogue were selected by criterion of having at least 5 gamma-quanta during the time interval of 1 ms, simultaneously in at least two gamma-spectrometer detectors. TGFs included in this catalogue have a typical duration of about 400 microseconds, and in total contain from 10 to 40 gamma-quanta. For each selected for catalogue TGF candidate, we will show light curve and a correlating data of other instruments of “RELEC” on-board Vernov satellite. Results of observations of trapped, quasi-trapped and precipitated electron flux and spectral variations in different areas in the near-Earth space including low L-shells in wide dynamical range from ~1 up to 104 part/cm2s are discussed in this report. (author)
DEFF Research Database (Denmark)
Jensen, Tue Vissing; Sørensen, Allan Hvidkjær
2013-01-01
A charged particle emits bremsstrahlung while traversing matter. We calculate the radiation cross section for bare heavy ions penetrating amorphous materials and single crystals at highly relativistic energies. The main component originates in scattering of the virtual photons of screened target...... in a pronounced directional dependence of the energy loss of bare heavy ions at extreme relativistic energies....
A monolithic relativistic electron beam source based on a dielectric laser accelerator structure
Energy Technology Data Exchange (ETDEWEB)
McNeur, Josh; Carranza, Nestor; Travish, Gil; Yin Hairong; Yoder, Rodney [UCLA Dept. of Physics and Astronomy, Los Angeles, CA 90095 (United States); College of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054 (China); Manhattanville College, Physics Dept., 2900 Purchase St., Purchase, NY 10577 (United States)
2012-12-21
Work towards a monolithic device capable of producing relativistic particle beams within a cubic-centimeter is detailed. We will discuss the Micro-Accelerator Platform (MAP), an optical laser powered dielectric accelerator as the main building block of this chip-scale source along with a field enhanced emitter and a region for sub-relativistic acceleration.
On the physics of relativistic double layers
International Nuclear Information System (INIS)
Carlqvist, P.
1982-06-01
A model of a strong, time-independent, and relativistic double layer is studied. Besides double layers having the electric field parallel to the current the model also describes a certain type of oblique double layers. The 'Langmuir condition' (ratio of ion current density to electron current density) as well as an expression for the potential drop of the double layer are derived. Furthermore, the distribution of charged particles, electric field, and potential within the double layer are clarified and discussed. It is found that the properties of relativistic double layers differ substantially from the properties of corresponding non-relativistic double layers. (Author)
Muon spin relaxation studies in strongly correlated electron systems
Uemura, Y. J.; Luke, G. M.
1993-05-01
We describe recent progress of muon spin relaxation (μSR) studies in heavy-fermion (HF) and other strongly correlated electron systems. Measurements of the magnetic field penetration depth λ in HF superconductors UPt 3, URu 2Si 2, UPd 2Al 3 and U 2PtC 2 have revealed that these systems are characterized by large ratios Tc/ TF = 0.1-0.01 of Tc vs Fermi temperature TF derived from λ. This feature is common to high- Tc cuprate and other exotic superconductors. Zero-field μSR studies of magnetic order have elucidated a cross-over from spin glass ordering to nonmagnetic ground states in the ‘quadrupolar Kondo regime’ of (Y 1- xU x)Pd 3, and also suggested a possibility of incommensurate spin-density-wave (SDW) ordering in UNi 2Al 3.
Liu, S.; Xiao, F.; Yang, C.; Zhou, Q.; He, Y.
2016-12-01
The possible acceleration mechanisms of relativistic electron fluxes in Earth's outer radiation belt are basically categorized into two groups: radial diffusion and in-situ acceleration. A physical understanding and modeling of the radiation belt dynamic require an investigation of the electron phase space density (PSD) to provide a delicate picture of the mechanisms. Here, we study the time evolution of relativistic electron PSD during two events. During 23 to 24 September, 2014, with minimum Dst=-27 nT and maximum Kp 4, relativistic (2.1 -3.4 MeV) electron fluxes and chorus waves were substantially enhanced at L=4.5-6 by the Van Allen Probes. Pronounced peaks in PSD radial profiles occurred at L*=4.9-5.2, suggesting a local acceleration process as the primary mechanism. Numerical calculation shows that bounce-averaged momentum diffusion coefficient from chorus wave approaches 10-5 s-1 at large pitch angle for 2 MeV electrons. Meanwhile, electromagnetic and electrostatic radial diffusion coefficients (DMLL and DELL) are smaller than approximately by 3-20 times and 25-100 times respectively. This indicates that chorus-electron interaction dominates the PSD evolution over the radial diffusion in this event. During 1 to 3 October, 2013, with minimum Dst=-67 nT and maximum Kp 8, relativistic electron fluxes increased by 1-2 orders at L=4.8-5.8, while chorus waves are not directly observed. The PSD radial profiles monotonically increases with L*. We find that DMLL and DELL can approach 10-4 s-1 and 10-5 s-1 respectively. Using inferred chorus intensity 50 pT, we obtain the momentum diffusion coefficient as about 10-6 s-1. The above calculations and observations indicated that the radial diffusion tends to be the dominant process for the PSD enhancement. The present results provide a direct support and reveal a typical picture for the previous statistical characteristics of radial PSD evolution related to different internal, magnetospheric processes. It further
Energy Technology Data Exchange (ETDEWEB)
Stanke, Monika, E-mail: monika@fizyka.umk.pl; Palikot, Ewa, E-mail: epalikot@doktorant.umk.pl [Institute of Physics, Faculty of Physics, Astronomy, and Informatics, Nicolaus Copernicus University, ul. Grudzia̧dzka 5, Toruń, PL 87-100 (Poland); Adamowicz, Ludwik, E-mail: ludwik@email.arizona.edu [Department of Chemistry and Biochemistry and Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States)
2016-05-07
Algorithms for calculating the leading mass-velocity (MV) and Darwin (D) relativistic corrections are derived for electronic wave functions expanded in terms of n-electron explicitly correlated Gaussian functions with shifted centers and without pre-exponential angular factors. The algorithms are implemented and tested in calculations of MV and D corrections for several points on the ground-state potential energy curves of the H{sub 2} and LiH molecules. The algorithms are general and can be applied in calculations of systems with an arbitrary number of electrons.
Energy Technology Data Exchange (ETDEWEB)
Badarin, A. A.; Kurkin, S. A. [Saratov State University (Russian Federation); Koronovskii, A. A. [Yuri Gagarin State Technical University (Russian Federation); Rak, A. O. [Belorussian State University of Informatics and Radioelectronics (Belarus); Hramov, A. E., E-mail: hramovae@gmail.com [Saratov State University (Russian Federation)
2017-03-15
The development and interaction of Bursian and diocotron instabilities in an annular relativistic electron beam propagating in a cylindrical drift chamber are investigated analytically and numerically as functions of the beam wall thickness and the magnitude of the external uniform magnetic field. It is found that the interaction of instabilities results in the formation of a virtual cathode with a complicated rotating helical structure and several reflection regions (electron bunches) in the azimuthal direction. It is shown that the number of electron bunches in the azimuthal direction increases with decreasing beam wall thickness and depends in a complicated manner on the magnitude of the external magnetic field.
Modeling the Proton Radiation Belt With Van Allen Probes Relativistic Electron-Proton Telescope Data
Selesnick, R. S.; Baker, D. N.; Kanekal, S. G.; Hoxie, V. C.; Li, X.
2018-01-01
An empirical model of the proton radiation belt is constructed from data taken during 2013-2017 by the Relativistic Electron-Proton Telescopes on the Van Allen Probes satellites. The model intensity is a function of time, kinetic energy in the range 18-600 MeV, equatorial pitch angle, and L shell of proton guiding centers. Data are selected, on the basis of energy deposits in each of the nine silicon detectors, to reduce background caused by hard proton energy spectra at low L. Instrument response functions are computed by Monte Carlo integration, using simulated proton paths through a simplified structural model, to account for energy loss in shielding material for protons outside the nominal field of view. Overlap of energy channels, their wide angular response, and changing satellite orientation require the model dependencies on all three independent variables be determined simultaneously. This is done by least squares minimization with a customized steepest descent algorithm. Model uncertainty accounts for statistical data error and systematic error in the simulated instrument response. A proton energy spectrum is also computed from data taken during the 8 January 2014 solar event, to illustrate methods for the simpler case of an isotropic and homogeneous model distribution. Radiation belt and solar proton results are compared to intensities computed with a simplified, on-axis response that can provide a good approximation under limited circumstances.
The theory and simulation of relativistic electron beam transport in the ion-focused regime
International Nuclear Information System (INIS)
Swanekamp, S.B.; Holloway, J.P.; Kammash, T.; Gilgenbach, R.M.
1992-01-01
Several recent experiments involving relativistic electron beam (REB) transport in plasma channels show two density regimes for efficient transport; a low-density regime known as the ion-focused regime (IFR) and a high-pressure regime. The results obtained in this paper use three separate models to explain the dependency of REB transport efficiency on the plasma density in the IFR. Conditions for efficient beam transport are determined by examining equilibrium solutions of the Vlasov--Maxwell equations under conditions relevant to IFR transport. The dynamic force balance required for efficient IFR transport is studied using the particle-in-cell (PIC) method. These simulations provide new insight into the transient beam front physics as well as the dynamic approach to IFR equilibrium. Nonlinear solutions to the beam envelope are constructed to explain oscillations in the beam envelope observed in the PIC simulations but not contained in the Vlasov equilibrium analysis. A test particle analysis is also developed as a method to visualize equilibrium solutions of the Vlasov equation. This not only provides further insight into the transport mechanism but also illustrates the connections between the three theories used to describe IFR transport. Separately these models provide valuable information about transverse beam confinement; together they provide a clear physical understanding of REB transport in the IFR
Potylitsyn, Alexander; Karataev, Pavel
2012-05-01
This volume contains papers presented at the IX International Symposium on Radiation from Relativistic Electrons in Periodic Structures (RREPS'11) which was held at Royal Holloway, University of London on September 12-16, Egham, United Kingdom. The symposium was organized jointly by Royal Holloway, University of London and Tomsk Polytechnic University, Tomsk, Russia. RREPS is a biennial series of symposia founded in September 1993 as an initiative of the Nuclear Physics Institute at Tomsk Polytechnic University. The intention was to strengthen the basic and applied research focused on radiation from relativistic electrons in condensed media, particularly from natural and artificial periodic structures, and to review the research activity in this area. Since then, the symposium has developed into a forum attracting young scientists from different areas of research and from many countries. Previous successful symposia were held at Tomsk, Russia (1993, 1995, 1997, 2003), Lake Baikal, Russia (1999), Lake Aiya, Altai, Russia (2001), Czech Technical University in Prague, Czech Republic (2007) and Zvenigorod, Moscow region, Russia (2009). As an outcome of the symposia the conference proceedings have been published in Nuclear Instruments and Methods in Physics Research, Section B (Vol. 145 No 1-2, October 1998; Vol. 173 No 1-2, January 2001; Vol. 201 No 1 January 2003; Vol. 227 No 1-2, January 2005; Vol. 266 No 17, September 2008) and Journal of Physics: Conference Series (Vol. 236, June 2010). The purpose of the present RREPS'11 symposium was to review the up-to-date situation in the area of electromagnetic radiation generated by relativistic charged particles in condensed media, and to discuss the research strategy for the near future. Nowadays, electromagnetic radiation studies cover electron energies from a few MeV up to hundreds of GeV in many laboratories throughout the world. The goal is to study the physics of the generation of various kinds of radiation and their
Directory of Open Access Journals (Sweden)
Agostino Marinelli
2010-11-01
Full Text Available Longitudinal space-charge forces from density fluctuations generated by shot noise can be a major source of microbunching instability in relativistic high brightness electron beams. The gain in microbunching due to this effect is broadband, extending at least up to optical frequencies, where the induced structure on the beam distribution gives rise to effects such as coherent optical transition radiation. In the high-frequency regime, theoretical and computational analyses of microbunching formation require a full three-dimensional treatment. In this paper we address the problem of space-charge induced optical microbunching formation in the high-frequency limit when transverse thermal motion due to finite emittance is included for the first time. We derive an analytical description of this process based on the beam’s plasma dielectric function. We discuss the effect of transverse temperature on the angular distribution of microbunching gain and its connection to the physics of Landau damping in longitudinal plasma oscillations. Application of the theory to a relevant experimental scenario is discussed. The analytical results obtained are then compared to the predictions arising from high resolution three-dimensional molecular dynamics simulations.
Energy Technology Data Exchange (ETDEWEB)
Ross, James Steven [Univ. of California, San Diego, CA (United States)
2010-01-01
Simultaneous scattering from electron-plasma waves and ion-acoustic waves is used to measure local laser-produced plasma parameters with high spatiotemporal resolution including electron temperature and density, average charge state, plasma flow velocity, and ion temperature. In addition, the first measurements of relativistic modifications in the collective Thomson scattering spectrum from thermal electron-plasma fluctuations are presented [1]. Due to the high phase velocity of electron-plasma fluctuations, relativistic effects are important even at low electron temperatures (T_{e} < 1 keV). These effects have been observed experimentally and agree well with a relativistic treatment of the Thomson scattering form factor [2]. The results are important for the interpretation of scattering measurements from laser produced plasmas. Thomson scattering measurements are used to characterize the hydrodynamics of a gas jet plasma which is the foundation for a broad series of laser-plasma interaction studies [3, 4, 5, 6]. The temporal evolution of the electron temperature, density and ion temperature are measured. The measured electron density evolution shows excellent agreement with a simple adiabatic expansion model. The effects of high temperatures on coupling to hohlraum targets is discussed [7]. A peak electron temperature of 12 keV at a density of 4.7 × 10^{20}cm^{-3} are measured 200 μm outside the laser entrance hole using a two-color Thomson scattering method we developed in gas jet plasmas [8]. These measurements are used to assess laser-plasma interactions that reduce laser hohlraum coupling and can significantly reduce the hohlraum radiation temperature.
Energy Technology Data Exchange (ETDEWEB)
Rostampooran, Shabnam; Dorranian, Davoud, E-mail: doran@srbiau.ac.ir [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
2016-08-15
A system of nonlinear one-dimensional equations of the electron hydrodynamics with Maxwell's equations was developed to describe electromagnetic (EM) solitons in plasma with nonthermal electrons. Equation of vector potential was derived in relativistic regime by implementing the multiple scales technique, and their solitonic answers were introduced. The allowed regions for bright and dark electromagnetic solitons were discussed in detail. Roles of number density of nonthermal electrons, temperature of electrons, and frequency of fast participate of vector potential on the Sagdeev potential and properties of EM soliton were investigated. Results show that with increasing the number of nonthermal electrons, the amplitude of vector potential of bright solitons increases. By increasing the number of nonthermal electrons, dark EM solitons may be changed to bright solitons. Increasing the energy of nonthermal electrons leads to generation of high amplitude solitons.
PREFACE: International Conference on Strongly Correlated Electron Systems (SCES 2011)
Littlewood, P. B.; Lonzarich, G. G.; Saxena, S. S.; Sutherland, M. L.; Sebastian, S. E.; Artacho, E.; Grosche, F. M.; Hadzibabic, Z.
2012-11-01
The Strongly Correlated Electron Systems Conference (SCES) 2011, was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 was dedicated to 100 years of superconductivity and covered a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The meeting welcomed to Cambridge 657 participants from 23 countries, who presented 127 talks (including 16 plenary, 57 invited, and 54 contributed) and 736 posters in 40 sessions over five full days of meetings. This proceedings volume contains papers reporting on the science presented at the meeting. This work deepens our understanding of the rich physical phenomena that arise from correlation effects. Strongly correlated systems are known for their remarkable array of emergent phenomena: the traditional subjects of superconductivity, magnetism and metal-insulator transitions have been joined by non-Fermi liquid phenomena, topologically protected quantum states, atomic and photonic gases, and quantum phase transitions. These are some of the most challenging and interesting phenomena in science. As well as the science driver, there is underlying interest in energy-dense materials, which make use of 'small' electrons packed to the highest possible density. These are by definition 'strongly correlated'. For example: good photovoltaics must be efficient optical absorbers, which means that photons will generate tightly bound electron-hole pairs (excitons) that must then be ionised at a heterointerface and transported to contacts; efficient solid state refrigeration depends on substantial entropy changes in a unit cell, with large local electrical or magnetic moments; efficient lighting is in a real sense the inverse of photovoltaics; the limit of an efficient battery is a supercapacitor employing mixed valent ions; fuel cells and solar to fuel conversion
Kitamura, K.; Nagatsuma, T.; Troshichev, O. A.; Obara, T.; Koshiishi, H.; Saita, S.; Yoshikawa, A.; Yumoto, K.
2014-12-01
In the present study the relativistic electron flux (0.59-1.18MeV) measured by Standard Dose Monitor (SDOM) onboard DRTS (KODAMA) satellite at the Geostationary Earth Orbit (GEO) is analyzed to investigate the long term (from 2002 to 2014) variations of the electron flux enhancement (REF) during the passage of Corotating Interaction Regions (CIRs) and/or Coronal Mass Ejection (CMEs). The long term variations of the REF clearly shows the 27-days period associated with the high speed solar wind velocity caused by the CIRs, whereas it is very few that the enhancement of REF lasts for several days after passage of CMEs. The 27-days period enhancement of REF represents the quite strong peak in 2003 when the high speed stream of the solar wind were quit active. We also conducted the same analysis for the Pc5 pulsations observed on the ground. The ground magnetic variations data globally observed by National Institute of Information and Communications Technology (NICT) and International Center for Space Weather Science and Education (ICSWSE) Kyushu University are used to investigate the long term variations of Pc5 power. The same signature in the REF variations is shown in the time variability of the Pc5 power on the ground. These results indicate that the solar wind condition strongly affects the acceleration process of the relativistic electron flux by the ULF wave. In particular the dependence of the REF and Pc5 variations on the sector structures and their seasonal variations strongly suggest that the relationship between Pc5 and REF variations could be controlled by the Russell-McPherron effect.
International Nuclear Information System (INIS)
Baifei Shen
2010-01-01
Complete text of publication follows. The triggering of wave-breaking in a three-dimensional laser plasma wake (bubble) with a nanowire is investigated. The Coulomb potential from the wire is used to disturb the wake field to initialize the wave-breaking. Controlled electron acceleration in the bubble regime is controlled by optimizing the plasma density. The origin of beam disparity in emittance and betatron oscillation orbits, in and out of the polarization plane of the drive laser of laser-plasma accelerators, is explained in terms of betatron oscillation driven by the laser field with simulation and a simple model. Proton trapping and acceleration by an electron bubble-channel structure in high-intensity laser interaction with high density plasma is investigated by using three-dimensional particle-in-cell simulations. It is shown that protons can be trapped, bunched, and efficiently accelerated for appropriate laser intensity and plasma density, and the proton acceleration is enhanced if the plasma consists mainly of heavier ions such as tritium. Theory and simulation of ion acceleration with electrostatic shock is given in detail. Electrostatic shock driven by linearly and circularly polarized laser pulse are compared. Multi stage shock acceleration for ultra thin foils is used to increase the efficiency of laser acceleration. The effect of plasma temperature of laser intensity is discussed. A sandwich target design with a thin compound ion layer between two light-ion layers and a micro-structured target design are proposed for obtaining efficiently monoenergetic heavy-ion beams. The foil thickness for light pressure acceleration is studied. Quasi-single cycle relativistic laser pulse is generated by laser-foil interaction.
Ultra-High-Contrast Laser Acceleration of Relativistic Electrons in Solid Targets
Higginson, Drew Pitney
The cone-guided fast ignition approach to Inertial Confinement Fusion requires laser-accelerated relativistic electrons to deposit kilojoules of energy within an imploded fuel core to initiate fusion burn. One obstacle to coupling electron energy into the core is the ablation of material, known as preplasma, by laser energy proceeding nanoseconds prior to the main pulse. This causes the laser-absorption surface to be pushed back hundreds of microns from the initial target surface; thus increasing the distance that electrons must travel to reach the imploded core. Previous experiments have shown an order of magnitude decrease in coupling into surrogate targets when intentionally increasing the amount of preplasma. Additionally, for electrons to deposit energy within the core, they should have kinetic energies on the order of a few MeV, as less energetic electrons will be stopped prior to the core and more energetic electrons will pass through the core without depositing much energy. Thus a quantitative understanding of the electron energy spectrum and how it responds to varied laser parameters is paramount for fast ignition. For the first time, this dissertation quantitatively investigates the acceleration of electrons using an ultra-high-contrast laser. Ultra-high-contrast lasers reduce the laser energy that reaches the target prior to the main pulse; drastically reducing the amount of preplasma. Experiments were performed in a cone-wire geometry relevant to fast ignition. These experiments irradiated the inner-tip of a Au cone with the laser and observed electrons that passed through a Cu wire attached to the outer-tip of the cone. The total emission of Kalpha x-rays is used as a diagnostic to infer the electron energy coupled into the wire. Imaging the x-ray emission allowed an effective path-length of electrons within the wire to be determined, which constrained the electron energy spectrum. Experiments were carried out on the ultra-high-contrast Trident laser
Babu, S. Ramesh; Badiger, N. M.; Karidurgannavar, M. Y.; Varghese, Jolly. G.
2018-04-01
The Mass Stopping Power (MSP) of relativistic electrons in chitosan loaded with TiO2 of different proportions has been measured by recording the spectrum of internal conversion electrons. The internal conversion electrons of energies 614 keV from Cs137, 942 keV and 1016 keV from Bi207 source are allowed to pass through chitosan-TiO2 alloy and transmitted electrons are detected with a Si (Li) detector coupled to an 8 K multichannel analyzer. By knowing the energies of incident electrons and transmitted electrons, the energy loss and the MSP are determined. Thus measured MSP values of the alloys are compared with the values calculated using Braggs additivity rule. The disagreement between theory and experiment is found to increases with increasing TiO2 concentration in chitosan, indicating the influence of chemical environment in the properties of such polymeric membrane.
DEFF Research Database (Denmark)
Kuznetsov, A.M.; Ulstrup, Jens
2002-01-01
We present a new view and an analytical formalism of electron flow through a donor-acceptor molecule inserted between a pair of metal electrodes. The donor and acceptor levels are strongly coupled to an environmental nuclear continuum. The formalism applies to molecular donor-acceptor systems both...... in vacuum or air, and in aqueous solution under electrochemical potential control. Multifarious patterns of rectified electron flow from the negatively to the positively biased electrode arise. The electronic interaction between the donor and acceptor fragments, mutually and with the electrodes, can be weak...
Energy Technology Data Exchange (ETDEWEB)
Martinolli, E
2003-04-15
This work is dedicated to the study of the energy deposition of fast electrons in matter. This topic is of prime importance for inertial fusion driven by laser since relativistic electrons are produced in laser-matter interaction for a laser operating in ultra-intense regime. This thesis is made up of: a theoretical chapter dealing with the generation and transport of fast electrons, of 2 chapters reporting experimental data obtained with optical and X-rays diagnostics at the laser facilities of LULI in France and RAL in U.K., and of a chapter dedicated to the simulation of electron transport by using a Monte-Carlo code combined to a hybrid collisional-electromagnetic PIC code. A new spectrometer has been designed: the detection of K{alpha} rays coming from a fluorescent layer embedded in the target has allowed us to assess the size of the electron beam and the level of ionisation. (A.C.)
Energy Technology Data Exchange (ETDEWEB)
Lee, Y.S.
1977-11-01
The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, Tl, Pb and Bi without 4f electrons and with atomic numbers reduced by 14. The relativistic effect estimated from the numerical Dirac-Hartree-Fock (DHF) calculations of those atoms is comparable in the magnitude with that of the 4f shell of electrons. Both are larger for 6s than for 5d or 6p electrons. The various relativistic effects on valence electrons are discussed in detail to determine the proper level of the approximation for the valence electron calculations of systems with heavy elements. An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials.
Energy densities of magnetic field and relativistic electrons at the innermost region of the M87 jet
Directory of Open Access Journals (Sweden)
Kino M.
2013-12-01
Full Text Available We explore energy densities of magnetic fields and relativistic electrons in M87 jet. Since the radio core at the base of the M87 jet is the optically thick surface against synchrotron self absorption (SSA, observations directly give the size and turnover frequency for SSA. Using the observed angular diameter 0.11 mas, which corresponds to 16 Schwarzschild radii of the central black hole with 6 × 109 solar mass, and the flux density of the radio core at 43 GHz, we estimate the energy densities of magnetic field (UB and relativistic electrons (Ue by comparing the standard SSA formula to the observed radio core. Together with the allowed total kinetic power of the M87 jet, we find that (i the allowed B is limited in the range 2 G ≤ B ≤ 13 G, and that (ii 0:18 ≤ Ue/UB ≤ 66 holds. Our results significantly constrain formation mechanism of relativistic jets in active galactic nuclei.
Alexander, LYSENKO; Iurii, VOLK
2018-03-01
We developed a cubic non-linear theory describing the dynamics of the multiharmonic space-charge wave (SCW), with harmonics frequencies smaller than the two-stream instability critical frequency, with different relativistic electron beam (REB) parameters. The self-consistent differential equation system for multiharmonic SCW harmonic amplitudes was elaborated in a cubic non-linear approximation. This system considers plural three-wave parametric resonant interactions between wave harmonics and the two-stream instability effect. Different REB parameters such as the input angle with respect to focusing magnetic field, the average relativistic factor value, difference of partial relativistic factors, and plasma frequency of partial beams were investigated regarding their influence on the frequency spectrum width and multiharmonic SCW saturation levels. We suggested ways in which the multiharmonic SCW frequency spectrum widths could be increased in order to use them in multiharmonic two-stream superheterodyne free-electron lasers, with the main purpose of forming a powerful multiharmonic electromagnetic wave.
International Nuclear Information System (INIS)
Shul'ga, N.F.; Truten', V.I.
1999-01-01
It is shown that a considerable decrease in a total cross-section of the elastic scattering of relativistic electrons by a crystal atomic string can take place at certain values of particle incidence angles. This effect is similar to the Ramsauer-Townsend effect of slow electrons scattering by an atom. It is shown that the decrease in the angle of particles incidence on the atomic string essentially changes the process of particles scattering. The phenomena of the particle rainbow scattering and orbiting may occur in this case. 14 refs., 5 figs
International Nuclear Information System (INIS)
Moir, D.C.; Faehl, R.J.; Newberger, B.S.; Thode, L.E.
1981-01-01
Near-term development of the existing PHERMEX standing-wave linac would provide a 40 to 60 MeV electron beam with a current of 3 kA capable of answering a number of fundamental issues concerning endoatmospheric, ultra-relativistic electron beam propagation. Inherent high-repetition rate and multiple-pulse capability would allow alternative propagation scenarios to be investigated. Much of the theoretical expertise required to support the technology development and time-resolved beam propagation experiments presently resides within the Theoretical Applications Division
Ivanov, I. A.; Burdakov, A. V.; Burmasov, V. S.; Kuklin, K. N.; Makarov, M. A.; Mekler, K. I.; Polosatkin, S. V.; Postupaev, V. V.; Rovenskikh, A. F.; Sidorov, E. N.; Sinitsky, S. L.; Sudnikov, A. V.
2017-02-01
Results of spectral and magnetic diagnostics of plasma differential rotation in the GOL-3 multiplemirror trap are presented. It is shown that the maximum frequency of plasma rotation about the longitudinal axis reaches 0.5 MHz during the injection of a relativistic electron beam into the plasma. The data of two diagnostics agree if there is a region with a higher rotation frequency near the boundary of the electron beam. Plasma differential rotation can be an additional factor stabilizing interchange modes in the GOL-3 facility.
International Nuclear Information System (INIS)
Burdakov, A.V.; Voropaev, S.G.; Kojdan, V.S.; Lebedev, S.V.; Meksler, K.I.; Nikiforov, A.A.; Postupaev, V.V.; Shcheglov, M.A.; Piffl, V.
1996-01-01
Significant non-collision beam brake action in plasma (decrease in electron average energy by approximately 25%) was obtained as a result of collective interaction of microsecond relativistic electron beam with plasma on the GOL-3 device. The beam of about 5 μs length and with energy up to 100 kJ was injected in plasma with density of approximately 10 15 cm -3 , located in the seven-meter solenoid with the field of 5 x 5 Tl. The plasma specific energy content remains heterogeneous by length during heating time with the maximum close to the beam injection point. 21 refs., 11 figs
International Nuclear Information System (INIS)
Kontorovich, V.M.; Kochanov, A.E.
1980-01-01
It is demonstrated that in the case of hard injection of relativistic electrons accompanied by the joint action of synchrotron (Compton) losses and energy-dependent spatial diffusion, a spectrum with 'breaks' is formed containing universal (with index γ = 2) and diffusion regions, both independent of the injection spectrum. The effect from non-linearity of the electron spectrum is considered in averaged electromagnetic spectra for various geometries of sources (sphere, disk, arm). It is shown that an universal region (with index α = 0.5) can occur in the radiation spectrum. (orig.)
Haba, Z
2009-02-01
We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.
Roelof, E. C.
2017-12-01
Voyager 1/2 LECP observations at the termination shock (TS) crossings established that energetic ions (40keV-1MeV) appeared to be locally accelerated "termination shock particles", and since then have exhibited remarkably steady and similar intensities at both spacecraft throughout the heliosheath (HS). On the other hand, the anomalous cosmic rays (ACRs, 4-80 MeV total energy H, He, and O ions) increased more or less steadily across the shock and then gradually peaked years later. All the time in the HS, the ACRs at each spacecraft exhibited a striking "common spectrum", i.e., closely similar intensity histories when ordered by total energy. Near-relativistic electrons (30 keV-1 MeV) exhibited seemingly mutually inconsistent behavior while the two Voyagers transited the shock and HS, with the VGR2 electrons peaking at the shock, but later disappearing for a year (in 2010) and then slowly recovering, as opposed to the less variable VGR1 electrons whose remarkably smooth time history (2008-2012) was very similar to the VGR1 ACRs. Consequently, shock acceleration seems to be operating locally at the TS along with another spatially distributed acceleration/transport mechanism within the HS. The "reservoir" equation (Roelof, AIP Conf. Proc., 1500, 174-179 and 180-184, 2012) offers quantitative explanations for many of these apparently disparate observations. Meso-scale gradients and curvatures in the magnetic field produce transverse transport of energetic particles and (in direct consequence) "transverse compressive" acceleration that relates the fractional rate of momentum d(lnp)/dt=-(1/3)div(Vperp) to the divergence of the component of the plasma velocity transverse to the magnetic field. However, this acceleration rate must compete with the extinction rate of singly-charged ions due to charge exchange with the cold interstellar neutral H-atoms that permeate the HS. The agreement of the Voyager 1/2 LECP observations with the acceleration/extinction processes has
Domínguez, Macarena; Muñoz, Víctor; Valdivia, Juan Alejandro
2012-05-01
The propagation of circularly polarized electromagnetic waves along a constant background magnetic field in an electron-positron plasma is calculated by means of both a fluid and a kinetic theory treatment. In the fluid theory, relativistic effects are included in the particle motion, the wave field, and in the thermal motion by means of a function f, which depends only on the plasma temperature. In this work we analyze the consistency of the fluid results with those obtained from a kinetic treatment, based on the relativistic Vlasov equation. The corresponding kinetic dispersion relation is numerically studied for various temperatures, and results are compared with the fluid treatment. Analytic expressions for the Alfvén velocity are obtained for the fluid and kinetic models, and it is shown that, in the kinetic treatment, the Alfvén branch is suppressed for large temperatures.
Superconductivity in strongly correlated electron systems: successes and open questions
International Nuclear Information System (INIS)
Shastry, B. Sriram
2000-01-01
Correlated electronic systems and superconductivity is a field which has unique track record of producing exciting new phases of matter. The article gives an overview of trends in solving the problems of superconductivity and correlated electronic systems
International Nuclear Information System (INIS)
Smith, A.C. Jr.
1977-01-01
The results of an experimental study on the trapping and energy loss mechanisms of intense, relativistic electron rings confined in Astron-like magnetic field geometries are presented. The work is subdivided into four sections: gas trapping; average ring electron energetics; plasma trapping, and hollow-beam cusp-injection into gas and plasma. The mechanisms by which the injected beam coalesces into a current ring in the existing Cornell RECE-Berta facility are considered. To investigate the nature of ring electron energy loss mechanisms following completion of the trapping process, a diagnostic was developed utilizing multi-foil X-ray absorption spectroscopy to analyze the Bremsstrahlung generated by the electrons as they impinge upon a thin tungsten wire target suspended in the circulating current. Finally, a set of preliminary experimental results is presented in which an annular electron beam was passed through a coaxial, non-adiabatic magnetic cusp located at one end of a magnetic mirror well
Hudson, M. K.; Jaynes, A. N.; Li, Z.; Malaspina, D.; Millan, R. M.; Patel, M.; Qin, M.; Shen, X.; Wiltberger, M. J.
2017-12-01
The two strongest storms of Solar Cycle 24, 17 March and 22 June 2015, provide a contrast between magnetospheric response to CME-shocks at equinox and solstice. The 17 March CME-shock initiated storm produced a stronger ring current response with Dst = - 223 nT, while the 22 June CME-shock initiated storm reached a minimum Dst = - 204 nT. The Van Allen Probes ECT instrument measured a dropout in flux for both events which can be characterized by magnetopause loss at higher L values prior to strong recovery1. However, rapid loss is seen at L 3 for the June storm at high energies with maximum drop in the 5.2 MeV channel of the REPT instrument coincident with the observation of EMIC waves in the H+ band by the EMFISIS wave instrument. The rapid time scale of loss can be determined from the 65 minute delay in passage of the Probe A relative to the Probe B spacecraft. The distinct behavior of lower energy electrons at higher L values has been modeled with MHD-test particle simulations, while the rapid loss of higher energy electrons is examined in terms of the minimum resonant energy criterion for EMIC wave scattering, and compared with the timescale for loss due to EMIC wave scattering which has been modeled for other storm events.2 1Baker, D. N., et al. (2016), Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015, J. Geophys. Res. Space Physics, 121, 6647-6660, doi:10.1002/2016JA022502. 2Li, Z., et al. (2014), Investigation of EMIC wave scattering as the cause for the BARREL 17 January 2013 relativistic electron precipitation event: A quantitative comparison of simulation with observations, Geophys. Res. Lett., 41, 8722-8729, doi:10.1002/2014GL062273.
Propagation and Loss-Cone Properties of Relativistic Electron Beams in the Magnetosphere
Sanchez, E. R.; Powis, A.; Greklek, M.; Porazik, P.; Kaganovich, I.
2017-12-01
One of the main obstacles for achieving closure of several key outstanding questions in magnetospheric physics has been the lack of accurate magnetic field mapping between processes or regions in the magnetosphere and their ionospheric foot-points. Accurate correspondence between magnetospheric processes or regions and their ionospheric foot-points can be achieved with beams of MeV electrons that propagate along magnetic-field lines in fractions of a second, emitted by compact linear accelerators under controlled conditions at specified points in the magnetosphere, while the atmospheric imprint created by their precipitation is detected by an array of ground-based optical imagers, radars, riometers or X-ray detectors. To prove that successful magnetic field mapping is possible, we must ensure that the beam can be injected into the loss cone, that the spacecraft potentials induced by the beam emission are manageable, that the beam propagates all the way into the topside ionosphere, and that the beam produces a signature detectable from the ground or from low altitude. In this work, we present the latest results of calculations of beam injection and propagation for a wide range of injection distances in the magnetotail equator and geomagnetic conditions to determine under what conditions beams emitted from the magnetosphere would be able to propagate to the topside ionosphere with enough intensity to be detected by ground-based or low-altitude instrumentation. Using ballistic simulations of charged particle motion, we demonstrate that relativistic electron beams can be successfully injected into the loss cone under both ideal (analytic dipole) and realistic (MHD modeled) magnetosphere conditions from a wide range of injection positions. For identical injection coordinates, the impact location on the top of the atmosphere is dependent on the current magnetosphere conditions, demonstrating that this technique can distinguish between the phases of a geomagnetic storm
International Nuclear Information System (INIS)
Using the covariant spectator theory and the transversity formalism, the unpolarized, coincidence cross section for deuteron electrodisintegration, d(e,e ' p)n, is studied. The relativistic kinematics are reviewed, and simple theoretical formulas for the relativistic impulse approximation (RIA) are derived and discussed. Numerical predictions for the scattering in the high Q 2 region obtained from the RIA and five other approximations are presented and compared. We conclude that measurements of the unpolarized coincidence cross section and the asymmetry A φ , to an accuracy that will distinguish between different theoretical models, is feasible over most of the wide kinematic range accessible at Jefferson Lab
Directory of Open Access Journals (Sweden)
Klimenko V.V.
2017-12-01
Full Text Available This paper presents the calculations of synchrotron radio emission intensity from Van Allen belts with Gaussian space distribution of electron density across L-shells of a dipole magnetic field, and with Maxwell’s relativistic electron energy distribution. The results of these calculations come to a good agreement with measurements of the synchrotron emission intensity of the artificial radiation belt’s electrons during the Starfish nuclear test. We have obtained two-dimensional distributions of radio brightness in azimuth — zenith angle coordinates for an observer on Earth’s surface. The westside and eastside intensity maxima exceed several times the maximum level of emission in the meridian plane. We have also constructed two-dimensional distributions of the radio emission intensity in decibels related to the background galactic radio noise level. Isotropic fluxes of relativistic electrons (Е~1 MeV should be more than 107 cm–2s–1 for the synchrotron emission intensity in the meridian plane to exceed the cosmic noise level by 0.1 dB (riometer sensitivity threshold.
International Nuclear Information System (INIS)
López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor; Viñas, Adolfo F.; Valdivia, J. Alejandro
2014-01-01
We use a kinetic treatment to study the linear transverse dispersion relation for a magnetized isotropic relativistic electron-positron plasma with finite relativistic temperature. The explicit linear dispersion relation for electromagnetic waves propagating along a constant background magnetic field is presented, including an analytical continuation to the whole complex frequency plane for the case of Maxwell-Jüttner velocity distribution functions. This dispersion relation is studied numerically for various temperatures. For left-handed solutions, the system presents two branches, the electromagnetic ordinary mode and the Alfvén mode. In the low frequency regime, the Alfvén branch has two dispersive zones, the normal zone (where ∂ω/∂k > 0) and an anomalous zone (where ∂ω/∂k < 0). We find that in the anomalous zone of the Alfvén branch, the electromagnetic waves are damped, and there is a maximum wave number for which the Alfvén branch is suppressed. We also study the dependence of the Alfvén velocity and effective plasma frequency with the temperature. We complemented the analytical and numerical approaches with relativistic full particle simulations, which consistently agree with the analytical results
Xiong, Ying; Chen, Lunjin; Xie, Lun; Fu, Suiyan; Xia, Zhiyang; Pu, Zuyin
2017-05-01
Dayside modulated relativistic electron's butterfly pitch angle distributions (PADs) from ˜200 keV to 2.6 MeV were observed by Van Allen Probe B at L = 5.3 on 15 November 2013. They were associated with localized magnetic dip driven by hot ring current ion (60-100 keV proton and 60-200 keV helium and oxygen) injections. We reproduce the electron's butterfly PADs at satellite's location using test particle simulation. The simulation results illustrate that a negative radial flux gradient contributes primarily to the formation of the modulated electron's butterfly PADs through inward transport due to the inductive electric field, while deceleration due to the inductive electric field and pitch angle change also makes in part contribution. We suggest that localized magnetic field perturbation, which is a frequent phenomenon in the magnetosphere during magnetic disturbances, is of great importance for creating electron's butterfly PADs in the Earth's radiation belts.
Schönlein, A.; Boutoux, G.; Pikuz, S.; Antonelli, L.; Batani, D.; Debayle, A.; Franz, A.; Giuffrida, L.; Honrubia, J. J.; Jacoby, J.; Khaghani, D.; Neumayer, P.; Rosmej, O. N.; Sakaki, T.; Santos, J. J.; Sauteray, A.
2016-05-01
We studied the interaction of a high-intensity laser with mass-limited Ti-wires. The laser was focused up to 7× 1020 \\text{W/cm}2 , with contrast of 10-10 to produce relativistic electrons. High-spatial-resolution X-ray spectroscopy was used to measure isochoric heating induced by hot electrons propagating along the wire up to 1 mm depth. For the first time it was possible to distinguish surface target regions heated by mixed plasma mechanisms from those heated only by the hot electrons that generate warm dense matter with temperatures up to 50 eV. Our results are compared to simulations that highlight both the role of electron confinement inside the wire and the importance of resistive stopping powers in warm dense matter.
Effect of strong coupling on interfacial electron transfer dynamics in ...
Indian Academy of Sciences (India)
Unknown
Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 e-mail: hnghosh@barc.gov.in. Abstract. Dynamics of interfacial electron transfer (ET) in ruthenium ..... As the localization takes place mostly on bpy-cat ligand, ILET process does not interfere much in the electron injection ...
Gravitationally confined relativistic neutrinos
Vayenas, C. G.; Fokas, A. S.; Grigoriou, D.
2017-09-01
Combining special relativity, the equivalence principle, and Newton’s universal gravitational law with gravitational rather than rest masses, one finds that gravitational interactions between relativistic neutrinos with kinetic energies above 50 MeV are very strong and can lead to the formation of gravitationally confined composite structures with the mass and other properties of hadrons. One may model such structures by considering three neutrinos moving symmetrically on a circular orbit under the influence of their gravitational attraction, and by assuming quantization of their angular momentum, as in the Bohr model of the H atom. The model contains no adjustable parameters and its solution, using a neutrino rest mass of 0.05 eV/c2, leads to composite state radii close to 1 fm and composite state masses close to 1 GeV/c2. Similar models of relativistic rotating electron - neutrino pairs give a mass of 81 GeV/c2, close to that of W bosons. This novel mechanism of generating mass suggests that the Higgs mass generation mechanism can be modeled as a latent gravitational field which gets activated by relativistic neutrinos.
Quantum Monte Carlo methods and strongly correlated electrons on honeycomb structures
Energy Technology Data Exchange (ETDEWEB)
Lang, Thomas C.
2010-12-16
In this thesis we apply recently developed, as well as sophisticated quantum Monte Carlo methods to numerically investigate models of strongly correlated electron systems on honeycomb structures. The latter are of particular interest owing to their unique properties when simulating electrons on them, like the relativistic dispersion, strong quantum fluctuations and their resistance against instabilities. This work covers several projects including the advancement of the weak-coupling continuous time quantum Monte Carlo and its application to zero temperature and phonons, quantum phase transitions of valence bond solids in spin-1/2 Heisenberg systems using projector quantum Monte Carlo in the valence bond basis, and the magnetic field induced transition to a canted antiferromagnet of the Hubbard model on the honeycomb lattice. The emphasis lies on two projects investigating the phase diagram of the SU(2) and the SU(N)-symmetric Hubbard model on the hexagonal lattice. At sufficiently low temperatures, condensed-matter systems tend to develop order. An exception are quantum spin-liquids, where fluctuations prevent a transition to an ordered state down to the lowest temperatures. Previously elusive in experimentally relevant microscopic two-dimensional models, we show by means of large-scale quantum Monte Carlo simulations of the SU(2) Hubbard model on the honeycomb lattice, that a quantum spin-liquid emerges between the state described by massless Dirac fermions and an antiferromagnetically ordered Mott insulator. This unexpected quantum-disordered state is found to be a short-range resonating valence bond liquid, akin to the one proposed for high temperature superconductors. Inspired by the rich phase diagrams of SU(N) models we study the SU(N)-symmetric Hubbard Heisenberg quantum antiferromagnet on the honeycomb lattice to investigate the reliability of 1/N corrections to large-N results by means of numerically exact QMC simulations. We study the melting of phases
Excitonic condensation in systems of strongly correlated electrons
Czech Academy of Sciences Publication Activity Database
Kuneš, Jan
2015-01-01
Roč. 27, č. 33 (2015), s. 333201 ISSN 0953-8984 Institutional support: RVO:68378271 Keywords : electronic correlations * exciton * Bose-Einstein condensation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.209, year: 2015
STIR: Novel Electronic States by Gating Strongly Correlated Materials
2016-03-01
TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6. AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES 15...REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8. PERFORMING ORGANIZATION REPORT NUMBER...channel limits induced electron density changes to approximately 1013 cm-2. This is sufficient to gate semiconducting materials, where the electronic
International Nuclear Information System (INIS)
Chen, C.
1994-01-01
A Pierce-type dispersion relation is derived for the interaction of an intense relativistic electron beam with a cylindrical slow-wave structure of arbitrary corrugation depth. It is shown that near a resonance, the Pierce parameter can be expressed in terms of the vacuum dispersion function and the beam current. The dispersion relation is valid in both the low-current (Compton) regime and the high-current (Raman) regime. The dispersion characteristics of the interaction, such as the linear instability growth rate and bandwidth, are analyzed for both regimes
International Nuclear Information System (INIS)
Piot, P.; Maxwell, T. J.; Sun, Y.-E; Ruan, J.; Lumpkin, A. H.; Thurman-Keup, R.; Rihaoui, M. M.
2011-01-01
We experimentally demonstrate the production of narrow-band (δf/f≅20% at f≅0.5THz) transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. The bunch train is generated via a transverse-to-longitudinal phase space exchange technique. We also show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.
Quantum fluid model of coherent stimulated radiation by a dense relativistic cold electron beam
Energy Technology Data Exchange (ETDEWEB)
Monteiro, L. F.; Serbeto, A.; Tsui, K. H. [Instituto de Física, Universidade Federal Fluminense, Campus da Praia Vermelha, Niterói, RJ 24210-346 (Brazil); Mendonça, J. T.; Galvão, R. M. O. [Instituto de Física, Universidade de São Paulo, São Paulo, SP 05508-090 (Brazil)
2013-07-15
Using a quantum fluid model, the linear dispersion relation for FEL pumped by a short wavelength laser wiggler is deduced. Subsequently, a new quantum corrected resonance condition is obtained. It is shown that, in the limit of low energy electron beam and low frequency pump, the quantum recoil effect can be neglected, recovering the classical FEL resonance condition, k{sub s}=4k{sub w}γ{sup 2}. On the other hand, for short wavelength and high energy electron beam, the quantum recoil effect becomes strong and the resonance condition turns into k{sub s}=2√(k{sub w}/λ{sub c})γ{sup 3/2}, with λ{sub c} being the reduced Compton wavelength. As a result, a set of nonlinear coupled equations, which describes the quantum FEL dynamics as a three-wave interaction, is obtained. Neglecting wave propagation effects, this set of equations is solved numerically and results are presented.
International Nuclear Information System (INIS)
Quesnel, Brice
1998-01-01
This research thesis reports a theoretical and numeric study of the behaviour of two non linear phenomena of the laser-plasma interaction physics in a relativistic regime: the electronic parametric instabilities, and the ponderomotive force. In a first part, the author establishes the three-dimensional scattering relationship of electron parametric instabilities for a circularly polarised wave propagating in a homogeneous and cold plasma, without limitations of wave intensity, nor of plasma density. Results are verified by comparison with those of two-dimensional numerical simulations. The Weibel instability is also briefly studied in relativistic regime. In the second part, the author establishes an expression of the ponderomotive force exerted by an ultra-intense laser pulse in the vacuum about the focus point. A numerical code of integration of equations of motion of an electron in the laser field is used for the different expressions corresponding different approximation degrees. Results are used to interpret a recent experiment, and to critic other theoretical works [fr
Baker, D. N.; Jaynes, A. N.; Li, X.; Henderson, M. G.; Kanekal, S. G.; Reeves, G. D.; Spence, H. E.; Claudepierre, S. G.; Fennell, J. F.; Hudson, M. K.
2014-01-01
The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth's radiation belts. Observations (up to E (is) approximately 10MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L (is) approximately 4.0 +/- 0.5). This reveals graphically that both 'competing' mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession.
Keith, Todd A; Frisch, Michael J
2011-11-17
Scalar-relativistic, all-electron density functional theory (DFT) calculations were done for free, neutral atoms of all elements of the periodic table using the universal Gaussian basis set. Each core, closed-subshell contribution to a total atomic electron density distribution was separately fitted to a spherical electron density function: a linear combination of s-type Gaussian functions. The resulting core subshell electron densities are useful for systematically and compactly approximating total core electron densities of atoms in molecules, for any atomic core defined in terms of closed subshells. When used to augment the electron density from a wave function based on a calculation using effective core potentials (ECPs) in the Hamiltonian, the atomic core electron densities are sufficient to restore the otherwise-absent electron density maxima at the nuclear positions and eliminate spurious critical points in the neighborhood of the atom, thus enabling quantum theory of atoms in molecules (QTAIM) analyses to be done in the neighborhoods of atoms for which ECPs were used. Comparison of results from QTAIM analyses with all-electron, relativistic and nonrelativistic molecular wave functions validates the use of the atomic core electron densities for augmenting electron densities from ECP-based wave functions. For an atom in a molecule for which a small-core or medium-core ECPs is used, simply representing the core using a simplistic, tightly localized electron density function is actually sufficient to obtain a correct electron density topology and perform QTAIM analyses to obtain at least semiquantitatively meaningful results, but this is often not true when a large-core ECP is used. Comparison of QTAIM results from augmenting ECP-based molecular wave functions with the realistic atomic core electron densities presented here versus augmenting with the limiting case of tight core densities may be useful for diagnosing the reliability of large-core ECP models in
International Nuclear Information System (INIS)
Newberger, B.S.; Thode, L.E.
1979-05-01
Experiments on the two-stream instability of a relativistic electron beam propagating through a neutral gas, carried out with the Lawrence Livermore Laboratory Astron beam, have been analyzed using a nonlinear saturation model for a cold beam. The behavior of the observed microwave emission due to the instability is in good agreement with that of the beam energy loss. Collisions on the plasma electrons weaken the nonlinear state of the instability but do not stabilize the mode. The beam essentially acts as if it were cold, a result substantiated by linear theory for waves propagating along the beam. In order to predict the effect of both beam momentum scatter and plasma electron collisions on the stability of the mode in future experiments a full two-dimensional linear theory must be developed
International Nuclear Information System (INIS)
Burdakov, A.V.; Voropaev, S.G.; Koidan, V.S.; Lebedev, S.V.; Mekler, K.I.; Nikiforov, A.A.; Postupaev, V.V.; Shcheglov, M.A.; Piffl, V.
1996-01-01
A considerable collisionless slowing of a beam in a plasma (a decrease in the mean electron energy by ∼25%) and transfer of a significant portion of the beam energy to the plasma are achieved as a result of the collective interaction of a microsecond relativistic electron beam with a plasma in the GOL-3 facility. A beam with a duration up to 5 μs and an energy up to 100 kJ is injected into a hydrogen plasma with a density ∼1015 cm-3 found in a 7-m solenoid with a field equal to 5.5 T. The specific energy content of the plasma remains longitudinally inhomogeneous during the heating period with a maximum near the point where the beam is injected. The parameters of the superthermal electrons born during the collective interaction are also determined. The features of the heating process and heat transfer in the plasma are discussed
International Nuclear Information System (INIS)
Regi, M.
2016-01-01
We focused the attention on the Pc5 geomagnetic pulsations in response to the solar wind forcing and their relationship with the relativistic electron flux at geostationary orbit. We present here the results of a correlation analysis between the Pc5 power in the magnetosphere and on the ground, at low and high latitude, and the solar-wind speed and fluctuation power of the interplanetary magnetic field and solar-wind dynamic pressure through the years 2006 to 2010, also showing the relative timing between pulsations and solar-wind parameters. The Pc5 power appears significantly correlated with simultaneous solar-wind pressure fluctuations and with the solar-wind speed lagged by several hours. The relative amplitude of the two correlation peaks depends on the solar cycle phase and on the latitude. We also show a strong relationship between the Pc5 power and the > 600 keV and > 2MeV electron flux at geosynchronous orbit. Clear evidence emerges that the electron flux follows the Pc5 power by about 2 days; the time delay is a bit longer for the higher-energy electrons.
Habash Krause, L.; Gilchrist, B. E.; Nishikawa, K.; Williams, A.
2013-12-01
Relativistic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and suborbital Reusable Launch Vehicle (sRLV) altitudes. The monoenergetic beam is modeled in cylindrical symmetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremmstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry that relies on sRLVs with a nominal apogee of 100 km. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.
Effect of strong coupling on interfacial electron transfer dynamics in ...
Indian Academy of Sciences (India)
Unknown
Bonnett R, Lambert C, Land E J, Scourides P A, Sin- clair R S and Truscott T G 1983 Photochem. Photo- biol. 38 1. 18. Mataga N 1991 in Electron transfer in inorganic, organic, and biological systems (eds) J R Bolton, N. Mataga and G McLendon (Advances in Chemistry. Series) (Washington, DC:) pp. 91–115. 19. Furube A ...
Electron dynamics in metals and semiconductors in strong THz fields
DEFF Research Database (Denmark)
Jepsen, Peter Uhd
2017-01-01
Semiconductors and metals respond to strong electric fields in a highly nonlinear fashion. Using single-cycle THz field transients it is possible to investigate this response in regimes not accessible by transport-based measurements. Extremely high fields can be applied without material damage...
International Nuclear Information System (INIS)
Rukhadze, A.A.
1981-01-01
Pulsed high-current electron beams with characteristic parameters: electron energy 10 5 -10 7 eV, electron current 10 3 -10 6 A, pulse duration 10 -8 -10 -6 s, beam energy 10 2 -10 6 J and power 10 8 -10 13 W, are widely used in different branches of science and technology such as controlled thermonuclear fusion, relativistic microwave electronics, powerful semiconductors, chemical and gaseous lasers, new principles of heavy-ion acceleration, and long-distance energy transmission. The paper discusses a new branch of science - pulsed high-current electronics, which has its own experimental technique and methods of theoretical analysis. Parts I and II determine what is meant by ''high current'' in an electron beam and calculate the maximum obtainable current values; these calculations are made for the simplest geometrical configurations realizable in practice. Current methods for theoretical analysis of high-current electron beam physics are described, together with classification of current experimental devices for generating such beams according to high-current parameters. The stability of electron beams is discussed and the concept of critical currents is introduced. Part III gives a detailed account of plasma-beam instability which occurs on the interaction of a high-current electron beam with high-density space-limited plasma. The linear and non-linear stages of beam instability are considered. The given theory is used for calculations for amplifiers and microwave generators of electromagnetic radiation. Finally, the experimental achievements in high-current relativistic microwave electronics are reviewed. (author)
Höfener, Sebastian; Ahlrichs, Reinhart; Knecht, Stefan; Visscher, Lucas
2012-12-07
We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] treatments for the 4p-block dimers Ga(2) to Br(2) , the 5p-block dimers In(2) to I(2) , and their atoms. Extended basis sets up to pentuple zeta are employed and energies extrapolated to the complete basis-set limit. Relativistic and non-relativistic results for the dissociation energy D(e) are in close agreement with each other and previously published data, provided non-relativistic or scalar-relativistic results are corrected for spin-orbit contributions taken from the literature. An exception is Te(2) where theoretical results scatter by 0.085 eV. By virtue of this agreement it is unexpected that comparison with the experimental D(0) or D(e) dissociation energies (zero-point vibrational effects are negligible in this context) reveal errors larger than 0.1 eV for Ga(2), Ge(2), and Sb(2). Only relativistic treatments are presented for the 6p-block cases Tl(2) to At(2). Sufficient agreement with experimental data is found only for Pb(2) and Bi(2), the deviation of the computed and experimental D(0) values for Po(2) is again larger than 0.1 eV. Deviations of 0.1 eV between the computed and experimental D(0) values are a major reason for concern and call for additional investigations in both fields to clarify the situation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Tanaka, M.; Sato, T.
1985-01-01
A new implicit macroscale electromagnetic particle simulation code (MARC) which allows a large scale length and a time step in multi-dimensions is described. Finite mass electrons and ions are used with relativistic version of the equation of motion. The electromagnetic fields are solved by using a complete set of Maxwell equations. For time integration of the field equations, a decentered (backward) finite differencing scheme is employed with the predictor - corrector method for small noise and super-stability. It is shown both in analytical and numerical ways that the present scheme efficiently suppresses high frequency electrostatic and electromagnetic waves in a plasma, and that it accurately reproduces low frequency waves such as ion acoustic waves, Alfven waves and fast magnetosonic waves. The present numerical scheme has currently been coded in three dimensions for application to a new tokamak current-drive method by means of relativistic electron beam injection. Some remarks of the proper macroscale code application is presented in this paper
Kozyreva, Olga; Antonova, Elizaveta
One of the main feature of the magnetospheric dynamics during magnetic storms is the motion of the auroral oval to the equator and the development of the powerful ring current. The main magnetic disturbances at the auroral latitudes are connected with the development of the westward electrojet. The motion of the auroral oval to the equator is accompanied by the motion to the equator of the auroral electrojet and the increase of the intensity of ultra low frequency (ULF) waves. We analyze the position of the auroral electrojet and ULF activity during magnetic storms for the period of Van Allen Probes mission. We also produce such analysis for a number of great magnetic storms with min Dst<-200 nT. We compare the localization of the position of the start of the increase of relativistic electrons for the Van Allen Probes period with the latitude of the westward electrojet and show that such increase is localized near its equatorial boundary. We compare the results of observations with the suggested theories of the acceleration of relativistic electrons.
Shao, X.; Fung, S. F.; Tan, L. C.; Sharma, A. S.
2010-01-01
Understanding the origin and acceleration of magnetospheric relativistic electrons (MREs) in the Earth's radiation belt during geomagnetic storms is an important subject and yet one of outstanding questions in space physics. It has been statistically suggested that during geomagnetic storms, ultra-low-frequency (ULF) Pc-5 wave activities in the magnetosphere are correlated with order of magnitude increase of MRE fluxes in the outer radiation belt. Yet, physical and observational understandings of resonant interactions between ULF waves and MREs remain minimum. In this paper, we show two events during storms on September 25, 2001 and November 25, 2001, the solar wind speeds in both cases were > 500 km/s while Cluster observations indicate presence of strong ULF waves in the magnetosphere at noon and dusk, respectively, during a approx. 3-hour period. MRE observations by the Los Alamos (LANL) spacecraft show a quadrupling of 1.1-1.5 MeV electron fluxes in the September 25, 2001 event, but only a negligible increase in the November 2.5, 2001 event. We present a detailed comparison between these two events. Our results suggest that the effectiveness of MRE acceleration during the September 25, 2001 event can be attributed to the compressional wave mode with strong ULF wave activities and the physical origin of MRE acceleration depends more on the distribution of toroidal and poloidal ULF waves in the outer radiation belt.
Strongly Coupled Magnetic and Electronic Transitions in Multivalent Strontium Cobaltites
Lee, J. H.; Choi, Woo Seok; Jeen, H.; Lee, H.-J.; Seo, J. H.; Nam, J.; Yeom, M. S.; Lee, H. N.
2017-01-01
The topotactic phase transition in SrCoO x (x = 2.5–3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO2.5 that is a room-temperature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO2.5, however, it has been conjectured t...
Curcio, A.; Anania, M.; Bisesto, F.; Botton, M.; Castellano, M.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Galletti, M.; Giulietti, D.; Henis, Z.; Petrarca, M.; Pompili, R.; Schleifer, E.; Zigler, A.
2018-02-01
Coherent radiation produced by relativistic charged bunches is nowadays of great interest for user-oriented applications and high-resolution diagnostics. Here we present experimental results obtained by using a temporal monitor based on the electro-optical sampling that allows us to reveal the features of the radiation emitted in terahertz range by ultrashort electron bunches moving in proximity to a nonlinear crystal. We investigate the radiation properties both in near- and far-field conditions by employing electron beams accelerated by a conventional photoinjector and through laser-plasma interactions. Our results indicate that the emitted radiation moves collinearly with the beam in one case, while its properties resemble those of the classical Cherenkov radiation in a second case.
Quantum phase transitions of strongly correlated electron systems
International Nuclear Information System (INIS)
Imada, Masatoshi
1998-01-01
Interacting electrons in solids undergo various quantum phase transitions driven by quantum fluctuations. The quantum transitions take place at zero temperature by changing a parameter to control quantum fluctuations rather than thermal fluctuations. In contrast to classical phase transitions driven by thermal fluctuations, the quantum transitions have many different features where quantum dynamics introduces a source of intrinsic fluctuations tightly connected with spatial correlations and they have been a subject of recent intensive studies as we see below. Interacting electron systems cannot be fully understood without deep analyses of the quantum phase transitions themselves, because they are widely seen and play essential roles in many phenomena. Typical and important examples of the quantum phase transitions include metal-insulator transitions, (2, 3, 4, 5, 6, 7, 8, 9) metal-superconductor transitions, superconductor-insulator transitions, magnetic transitions to antiferromagnetic or ferromagnetic phases in metals as well as in Mott insulators, and charge ordering transitions. Here, we focus on three different types of transitions
Strong-field control landscapes of coherent electronic excitation
Bayer, Tim; Wollenhaupt, Matthias; Baumert, Thomas
2008-04-01
We report on physical mechanisms behind resonant strong-field coherent control. To this end, we study multi-photon ionization of potassium atoms using intense shaped femtosecond laser pulses. The measured photoelectron spectra are discussed in terms of selective population of dressed states (SPODS). A physically motivated pulse parameterization is introduced which opens up two-dimensional parameter spaces comprising pulse sequences as well as chirped pulses. The control topologies of these subspaces are mapped out experimentally and are presented in the form of strong-field control landscapes (SFCLs). In the SFCLs, complementary realizations of SPODS via photon locking and rapid adiabatic passage are observed. Moreover, the combined effect, termed Multi-RAP, arises when both mechanisms are at play simultaneously. In order to better understand the performance of adaptive optimization procedures, we experimentally study their capability to find optimal solutions on a given parameter space. The evolution of different optimization procedures is visualized by means of control trajectories on the surface of the measured SFCL.
Relativistic effects on plasma expansion
Energy Technology Data Exchange (ETDEWEB)
Benkhelifa, El-Amine; Djebli, Mourad, E-mail: mdjebli@usthb.dz [USTHB, Faculty of Physics, Theoretical Physics Laboratory, B.P. 32 Bab-Ezzouar, 16079 Algiers (Algeria)
2014-07-15
The expansion of electron-ion plasma is studied through a fully relativistic multi-fluids plasma model which includes thermal pressure, ambipolar electrostatic potential, and internal energy conversion. Numerical investigation, based on quasi-neutral assumption, is performed for three different regimes: nonrelativistic, weakly relativistic, and relativistic. Ions' front in weakly relativistic regime exhibits spiky structure associated with a break-down of quasi-neutrality at the expanding front. In the relativistic regime, ion velocity is found to reach a saturation limit which occurs at earlier stages of the expansion. This limit is enhanced by higher electron velocity.
Kim, Kyung-Chan; Shprits, Yuri; Subbotin, Dmitriy; Ni, Binbin
2012-08-01
Understanding the dynamics of relativistic electron acceleration, loss, and transport in the Earth's radiation belt during magnetic storms is a challenging task. The U.S. National Science Foundation's Geospace Environment Modeling (GEM) has identified five magnetic storms for in-depth study that occurred during the second half of the Combined Release and Radiation Effects Satellite (CRRES) mission in the year 1991. In this study, we show the responses of relativistic radiation belt electrons to the magnetic storms by comparing the time-dependent 3-D Versatile Electron Radiation Belt (VERB) simulations with the CRRES MEA 1 MeV electron observations in order to investigate the relative roles of the competing effects of previously proposed scattering mechanisms at different storm phases, as well as to examine the extent to which the simulations can reproduce observations. The major scattering processes in our model are radial transport due to Ultra Low Frequency (ULF) electromagnetic fluctuations, pitch angle and energy diffusion including mixed diffusion by whistler mode chorus waves outside the plasmasphere, and pitch angle scattering by plasmaspheric hiss inside the plasmasphere. The 3-D VERB simulations show that during the storm main phase and early recovery phase the estimated plasmapause is located deep in the inner region, indicating that pitch angle scattering by chorus waves can be a dominant loss process in the outer belt. We have also confirmed the important role played by mixed energy-pitch angle diffusion by chorus waves, which tends to reduce the fluxes enhanced by local acceleration, resulting in comparable levels of computed and measured fluxes. However, we cannot reproduce the more pronounced flux dropout near the boundary of our simulations during the main phase, which indicates that non-adiabatic losses may extend toL-shells lower than our simulation boundary. We also provide a detailed description of simulations for each of the GEM storm events.
Inelastic electron scattering influence on the strong coupling oxide superconductors
International Nuclear Information System (INIS)
Gabovich, A.M.; Voitenko, A.I.
1995-01-01
The superconducting order parameters Δ and energy gap Δ g are calculated taking into account the pair-breaking inelastic quasiparticle scattering by thermal Bose-excitations, e.g., phonons. The treatment is self-consistent because the scattering amplitude depends on Δ. The superconducting transition for any strength of the inelastic scattering is the phase transition of the first kind and the dependences Δ (T) and Δ g (T) tend to rectangular curve that agrees well with the experiment for high-Tc oxides. On the basis of the developed theory the nuclear spin-lattice relaxation rate R s in the superconducting state is calculated. The Hebel-Slichter peak in R s (T) is shown to disappear for strong enough inelastic scattering
Sharma, Lalita; Sahoo, Bijaya Kumar; Malkar, Pooja; Srivastava, Rajesh
2018-01-01
A relativistic coupled-cluster theory is implemented to study electron impact excitations of atomic species. As a test case, the electron impact excitations of the 3 s 2 S 1/2-3 p 2 P 1/2;3/2 resonance transitions are investigated in the singly charged magnesium (Mg+) ion using this theory. Accuracies of wave functions of Mg+ are justified by evaluating its attachment energies of the relevant states and compared with the experimental values. The continuum wave function of the projectile electron are obtained by solving Dirac equations assuming distortion potential as static potential of the ground state of Mg+. Comparison of the calculated electron impact excitation differential and total cross-sections with the available measurements are found to be in very good agreements at various incident electron energies. Further, calculations are carried out in the plasma environment in the Debye-Hückel model framework, which could be useful in the astrophysics. Influence of plasma strength on the cross-sections as well as linear polarization of the photon emission in the 3 p 2 P 3/2-3 s 2 S 1/2 transition is investigated for different incident electron energies.
Handbook of relativistic quantum chemistry
Energy Technology Data Exchange (ETDEWEB)
Liu, Wenjian (ed.) [Peking Univ., Beijing (China). Center for Computational Science and Engineering
2017-03-01
This handbook focuses on the foundations of relativistic quantum mechanics and addresses a number of fundamental issues never covered before in a book. For instance: How can many-body theory be combined with quantum electrodynamics? How can quantum electrodynamics be interfaced with relativistic quantum chemistry? What is the most appropriate relativistic many-electron Hamiltonian? How can we achieve relativistic explicit correlation? How can we formulate relativistic properties? - just to name a few. Since relativistic quantum chemistry is an integral component of computational chemistry, this handbook also supplements the ''Handbook of Computational Chemistry''. Generally speaking, it aims to establish the 'big picture' of relativistic molecular quantum mechanics as the union of quantum electrodynamics and relativistic quantum chemistry. Accordingly, it provides an accessible introduction for readers new to the field, presents advanced methodologies for experts, and discusses possible future perspectives, helping readers understand when/how to apply/develop the methodologies.
Directory of Open Access Journals (Sweden)
M. Füllekrug
2011-01-01
Full Text Available Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables an experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which observes 100 kHz radio waves from fifty terrestrial Long Range Aid to Navigation (LORAN transmitters. Their mean luminosity patch in the plasmasphere is a circular area with a radius of 300 km and a power density of 22 μW/Hz as observed at 660 km height above the ground. The luminosity patches exhibit a southward displacement of 450 km with respect to the locations of the LORAN transmitters. The displacement is reduced to 150 km when an upward propagation of the radio waves along the geomagnetic field line is assumed. This residual displacement indicates that the radio waves undergo 150 km sub-ionospheric propagation prior to entering a magnetospheric duct and escaping into near-Earth space. The residual displacement at low (L < 2.14 and high (L > 2.14 geomagnetic latitudes ranges from 100 km to 200 km which suggests that the smaller inclination of the geomagnetic field lines at low latitudes helps to trap the radio waves and to keep them in the magnetospheric duct. Diffuse luminosity areas are observed northward of the magnetic conjugate locations of LORAN transmitters at extremely low geomagnetic latitudes (L < 1.36 in Southeast Asia. This result suggests that the propagation along the geomagnetic field lines results in a spatial spreading of the radio wave energy over distances of 1 Mm. The summative assessment of the electric field intensities measured in space show that nadir observations of terrestrial 100 kHz radio waves, e.g., from
Hao, Y. X.; Zong, Q.-G.; Zhou, X.-Z.; Rankin, R.; Chen, X. R.; Liu, Y.; Fu, S. Y.; Spence, H. E.; Blake, J. B.; Reeves, G. D.
2017-08-01
We present an analysis of "boomerang-shaped" pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.
Faure, Jérôme; Guénot, Diego; Gustas, Dominykas; Vernier, Aline; Beaurepaire, Benoît; Böhle, Frederik; López-Martens, Rodrigo; Lifschitz, Agustin
2017-05-01
Laser-plasma accelerators are usually driven by 100-TW class laser systems with rather low repetition rates. However, recent years have seen the emergence of laser-plasma accelerators operating with kHz lasers and energies lower than 10 mJ. The high repetition-rate is particularly interesting for applications requiring high stability and high signal-to-noise ratio but lower energy electrons. For example, our group recently demonstrated that kHz laser-driven electron beams could be used to capture ultrafast structural dynamics in Silicon nano-membranes via electron diffraction with picosecond resolution. In these first experiments, electrons were injected in the density gradients located at the plasma exit, resulting in rather low energies in the 100 keV range. The electrons being nonrelativistic, the bunch duration quickly becomes picosecond long. Relativistic energies are required to mitigate space charge effects and maintain femtosecond bunches. In this paper, we will show very recent results where electrons are accelerated in laser-driven wakefields to relativistic energies, reaching up to 5 MeV at kHz repetition rate. The electron energy was increased by nearly two orders of magnitude by using single-cycle laser pulses of 3.5 fs, with only 2.5 mJ of energy. Using such short pulses of light allowed us to resonantly excite high amplitude and nonlinear plasma waves at high plasma density, ne=1.5-2×1020 cm-3, in a regime close to the blow-out regime. Electrons had a peaked distribution around 5 MeV, with a relative energy spread of 30 %. Charges in the 100's fC/shot and up to pC/shot where measured depending on plasma density. The electron beam was fairly collimated, 20 mrad divergence at Full Width Half Maximum. The results show remarkable stability of the beam parameters in terms of beam pointing and electron distribution. 3D PIC simulations reproduce the results very well and indicate that electrons are injected by the ionization of Nitrogen atoms, N5+ to N6
Energy Technology Data Exchange (ETDEWEB)
Dunning, Michael
2012-07-19
We report generation of density modulation at terahertz (THz) frequencies in a relativistic electron beam through laser modulation of the beam longitudinal phase space. We show that by modulating the energy distribution of the beam with two lasers, density modulation at the difference frequency of the two lasers can be generated after the beam passes through a chicane. In this experiment, density modulation around 10 THz was generated by down-converting the frequencies of an 800 nm laser and a 1550 nm laser. The central frequency of the density modulation can be tuned by varying the laser wavelengths, beam energy chirp, or momentum compaction of the chicane. This technique can be applied to accelerator-based light sources for generation of coherent THz radiation and marks a significant advance toward tunable narrow-band THz sources.
Kinetic magnetization by fast electrons in laser-produced plasmas at sub-relativistic intensities
Pisarczyk, Tadeusz; Gus'kov, Sergey Yu.; Chodukowski, Tomasz; Dudzak, Roman; Korneev, Philipp; Demchenko, Nicolai N.; Kalinowska, Zofia; Dostal, Jan; Zaras-Szydlowska, Agnieszka; Borodziuk, Stefan; Juha, Libor; Cikhardt, Jakub; Krasa, Josef; Klir, Daniel; Cikhardtova, Balzhima; Kubes, Pavel; Krousky, Eduard; Krus, Miroslav; Ullschmied, Jiri; Jungwirth, Karel; Hrebicek, Jan; Medrik, Tomas; Golasowski, Jiri; Pfeifer, Miroslav; Renner, Oldrich; Singh, Sushil; Kar, Satyabrata; Ahmed, Hamad; Skala, Jiri; Pisarczyk, Pawel
2017-10-01
The problem of spontaneous magnetic field generation with nanosecond laser pulses raises a series of fundamental questions, including the intrinsic magnetization mechanisms in laser-driven plasmas and the understanding of charge-discharge processes in the irradiated target. These two issues are tightly bound as the charge-discharge processes are defined by the currents, which have in turn a feedback by magnetic fields in the plasma. Using direct polaro-interferometric measurements and theoretical analysis, we show that at parameters related to the PALS laser system ( 1.315 μ m, 350 ps, and 1016 W/cm2), fast electrons play a decisive role in the generation of magnetic fields in the laser-driven plasma. Spatial distributions of electric currents were calculated from the measured magnetic field and plasma density distributions. The obtained results revealed the characteristics of strong currents observed in capacitor-coil magnetic generation schemes and open a new approach to fundamental studies related to magnetized plasmas.
Directory of Open Access Journals (Sweden)
Pacheco Daniel
2017-01-01
Full Text Available We study two consecutive solar near-relativistic (>50 keV electron events observed on 2014 August 1 by both STEREO spacecraft with a longitudinal separation of only about 35°. The events were unambiguously associated with a solar source location and not accompanied by type II radio bursts or coronal mass ejections. Despite their close location, the two spacecraft were embedded in different solar wind streams and the electron intensities observed by the two STEREOs showed clear differences in onset times, peak intensities and pitch-angle distributions. The apparently better connected spacecraft, STEREO B, observed a smaller and more isotropic intensity increase and a later event onset time than STEREO A. Since the interplanetary transport conditions of solar energetic particles (SEPs have a direct influence on the characteristics of the observed temporal profiles and the particle anisotropies at the spacecraft location, our aim is to understand if the observations on 2014 August 1 could be explained by different interplanetary transport conditions along each flux tube connecting the spacecraft with the solar source. For that purpose, we use a Monte Carlo interplanetary transport model combined with an inversion procedure to fit the in-situ observations of the two near-relativistic multi-spacecraft electron events. This allows us to obtain the injection profiles at the Sun and infer the transport conditions, which are characterized by the electron radial mean free path, λr. We obtain an almost simultaneous release of electrons for both spacecraft in both events. The release is consistent with the timing and duration of the type III radio burst emission and it is larger for STEREO B, the better connected spacecraft. In addition, we obtain different transport conditions in different solar wind streams. We find that the stream in which STEREO B was embedded was more diffusive (λr = 0.1AU for Event I and λr = 0.06AU for Event II than the
DEFF Research Database (Denmark)
Hofener, S.; Ahlrichs, R.; Knecht, S.
2012-01-01
errors larger than 0.1 eV for Ga2, Ge2, and Sb2. Only relativistic treatments are presented for the 6p-block cases Tl2 to At2. Sufficient agreement with experimental data is found only for Pb2 and Bi2, the deviation of the computed and experimental D0 values for Po2 is again larger than 0.1 e...
International Nuclear Information System (INIS)
Roussel, Eleonore
2014-01-01
Relativistic electron bunches circulating in storage rings are used to produce intense radiation from far-infrared to X-rays. However, above a density threshold value, the interaction between the electron bunch and its own radiation can lead to a spatio-temporal instability called micro bunching instability. This instability is characterized by a strong emission of coherent THz radiation (typically 105 times stronger than the classical synchrotron radiation) which is a signature of the presence of microstructures (at mm scale) in the electron bunch. This instability is known to be a fundamental limitation of the operation of synchrotron light sources at high beam current. In this thesis, we have focused on this instability from a nonlinear dynamics point of view by combining experimental studies carried out at the Synchrotron Soleil and UVSOR storage rings with numerical studies mainly based on the Vlasov-Fokker-Planck equation. In a first step, due to the very indirect nature of the experimental observations, we have sought to deduce information on the microstructure wavenumber either by looking at the temporal evolution of the THz signal emitted during the instability or by studying the response of the electron bunch to a laser perturbation. In a second step, we have achieved direct, real time observations of the microstructures dynamics through two new, very different, detection techniques: a thin-film superconductor-based detector at UVSOR, and a spectrally-encoded electro-optic detection technique at Soleil. These new available experimental observations have allowed severe comparisons with the theoretical models. (author)
Krause, L. Habsh; Gilchrist, B. E.; Nishikawa, Ken-Ichi
2013-01-01
Relativisitic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and space reuseable launch vehicles (sRLVs). The monoenergetic beam is modeled in cylindrical symetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremsstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.
Zocco, Alessandro
2017-12-01
The properties of a non-relativistic magnetised low-beta electron-positron plasma in slab geometry are investigated. The two species are taken to be drift kinetic while we retain Larmor radius effects in quasi-neutrality, and inertia in Ohm's law. A linear analysis shows that, for small magnetic perturbations, Alfvénic perturbations travel at the electron Alfvén speed, which is based on the electron mass. We discuss the role of the displacement current when Larmor-scale and Debye-scale effects are both retained. We predict the existence of a kinetic electron Alfvén wave which connects to the K-modes of Mishchenko et al. (J. Plasma Phys., 2017 (submitted)) in the electrostatic limit. It is found that linear drift waves are not supported by the system if the two species have the same temperature. Tearing modes can be driven unstable by equilibrium current density gradients. Also in this case, the characteristic time is based on the electron Alfvén speed. Nonlinear hybrid fluid-kinetic equations are also derived. It is shown that each species is described, to leading order, by the kinetic reduced electron heating model (KREHM) kinetic equation of Zocco & Schekochihin (Phys. Plasmas, vol. 18, 2011, 102309). The model is extended to retain first-order Larmor radius effects. It supports collisionless dispersive waves, which can greatly impact nonlinear magnetic reconnection. Diamagnetic effects enter the nonlinear equations via the first-order magnetic compressibility. A minimal nonlinear model for two-dimensional low-frequency isothermal pair plasmas is derived.
International Nuclear Information System (INIS)
Miller, J.D.
1989-01-01
Experiments have been performed demonstrating efficient transport of long-pulse (380 ns), high-current (200 A), relativistic electron beams (REBs) in preformed plasma channels in the ion focus regime (IFR). Plasma channels were created by low-energy ( e , and channel ion mass, in agreement with theoretical values predicted for the ion hose instability. Microwave emission has also been observed indicative of REB-plasma electron two-stream instability. Plasma channel density measurements indicate that the two-stream instability can become dominant for measured f e values slightly above unity. The author has introduced a theoretical analysis for high-current REB transport and modulation in axially periodic IFR plasma channels. Analytic expression for the electric field are found for the case of a cosine modulation of the channel ion density. Two different types of channels are considered: (i) periodic beam-induced ionization channels, and (ii) periodic plasma slab channels created by an external source. Analytical conditions are derived for the matched radius of the electron beam and for approximate beam envelope motion using a 'smooth' approximation. Numerical solutions to the envelope equation show that by changing the wavelength or the amplitude of the space-charge neutralization fraction of the ion channel density modulation, the beam can be made to focus and diverge, or to undergo stable, modulated transport
Energy Technology Data Exchange (ETDEWEB)
Decker, J.; Peysson, Y
2004-12-01
A new original code for solving the 3-D relativistic and bounce-averaged electron drift kinetic equation is presented. It designed for the current drive problem in tokamak with an arbitrary magnetic equilibrium. This tool allows self-consistent calculations of the bootstrap current in presence of other external current sources. RF current drive for arbitrary type of waves may be used. Several moments of the electron distribution function are determined, like the exact and effective fractions of trapped electrons, the plasma current, absorbed RF power, runaway and magnetic ripple loss rates and non-thermal Bremsstrahlung. Advanced numerical techniques have been used to make it the first fully implicit (reverse time) 3-D solver, particularly well designed for implementation in a chain of code for realistic current drive calculations in high {beta}{sub p} plasmas. All the details of the physics background and the numerical scheme are presented, as well a some examples to illustrate main code capabilities. Several important numerical points are addressed concerning code stability and potential numerical and physical limitations. (authors)
International Nuclear Information System (INIS)
Zhang Jiatai; Xu Linbao; Chang Tieqiang
1990-04-01
An one and a half dimensional (one space dimension and two velocity components) relativistic electromagnetic cloud-in-cell simulation code CIC-R, which is suitable for simulating FEL process, has been developed. By using this code the temporal evolution of FEL is simulated and the linear growth rate of unstable spectra (For one simulation the growth rate is 0.07 which is in good agreement with the theoretical data.), dispersion relations of coupling of pump waves, the electromagnetic and electrostatic waves are obtained. Other results such as the behaviour of electron distribution function, electrons bunching in phase space, nonlinear saturation and efficiency of energy conversion are also considered. Besides the multi-mode particle simulation, a single-mode wave-particle code (SMWPC) is developed. It is based on the simplified single-mode theory which was obtained from equations of electron motion and radiation field derived strictly under one dimension assumption and single-mode approximation. Using this code a 3.459 mm Raman FEL has been simulated. The higher gamma and tapered wiggler of FEL are also simulated. The results show that the efficiency can reach to 48% if the tapered wiggler field and other parameters are properly designed
Vereshchagin, Gregory V.; Aksenov, Alexey G.
2017-02-01
Preface; Acknowledgements; Acronyms and definitions; Introduction; Part I. Theoretical Foundations: 1. Basic concepts; 2. Kinetic equation; 3. Averaging; 4. Conservation laws and equilibrium; 5. Relativistic BBGKY hierarchy; 6. Basic parameters in gases and plasmas; Part II. Numerical Methods: 7. The basics of computational physics; 8. Direct integration of Boltzmann equations; 9. Multidimensional hydrodynamics; Part III. Applications: 10. Wave dispersion in relativistic plasma; 11. Thermalization in relativistic plasma; 12. Kinetics of particles in strong fields; 13. Compton scattering in astrophysics and cosmology; 14. Self-gravitating systems; 15. Neutrinos, gravitational collapse and supernovae; Appendices; Bibliography; Index.
'Antigravity' Propulsion and Relativistic Hyperdrive
Felber, Franklin S.
2006-01-01
Exact payload trajectories in the strong gravitational fields of compact masses moving with constant relativistic velocities are calculated. The strong field of a suitable driver mass at relativistic speeds can quickly propel a heavy payload from rest to a speed significantly faster than the driver, a condition called hyperdrive. Hyperdrive thresholds and maxima are calculated as functions of driver mass and velocity.
Simulation of wake potentials induced by relativistic proton bunches in electron clouds
Energy Technology Data Exchange (ETDEWEB)
Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder (TEMF)
2012-07-01
Electron clouds limit the intensity of modern high intensity hadron accelerators. Presently electron clouds are the main limiting factor for the LHC operation with 25 ns bunch trains. The bunches passing through an electron cloud induce a wake field. When the electron cloud density exceeds a certain threshold beam instabilities occur. The presence of electron clouds results in a shift of the synchronous phase, which increases if the bunch spacing is reduced. For LHC and SPS conditions we compare the longitudinal electron cloud wake potentials and stopping powers obtained using a simplified 2D electrostatic Particle-in-Cell code with fully electromagnetic simulations using VORPAL. In addition we analyze the wake fields induced by displaced or tilted bunches.
Energy Technology Data Exchange (ETDEWEB)
Geloni, Gianluca; Ilinski, Petr; Saldin, Evgeni; Schneidmiller, Evgeni; Yurkov, Mikhail
2009-05-15
We describe a novel technique to characterize ultrashort electron bunches in Xray Free-Electron Lasers. Namely, we propose to use coherent Optical Transition Radiation to measure three-dimensional (3D) electron density distributions. Our method relies on the combination of two known diagnostics setups, an Optical Replica Synthesizer (ORS) and an Optical Transition Radiation (OTR) imager. Electron bunches are modulated at optical wavelengths in the ORS setup.When these electron bunches pass through a metal foil target, coherent radiation pulses of tens MW power are generated. It is thereafter possible to exploit advantages of coherent imaging techniques, such as direct imaging, diffractive imaging, Fourier holography and their combinations. The proposed method opens up the possibility of real-time, wavelength-limited, single-shot 3D imaging of an ultrashort electron bunch. (orig.)
Precipitation of trapped relativistic electrons by amplified whistler waves in the magnetosphere
International Nuclear Information System (INIS)
Kuo, S. P.; Kuo, Steven S.; Huynh, James T.; Kossey, Paul
2007-01-01
Numerical study of a loss-cone negative mass instability to amplify whistler waves by energetic electrons in the radiation belts is presented. The results show that a very low intensity whistler wave can be amplified by 50 keV electrons more than 25 dB, consistent with the Siple experimental result [Helliwell et al., J. Geophys. Res. 85, 3360 (1980)]. The dependencies of the amplification factor on the energetic electron density and on the initial wave intensity are evaluated. It is shown that the amplification factor decreases as the initial wave intensity increases. However, this gain can still exceed 15 dB for a 30 dB increase of the initial wave intensity, which is needed for the purpose of precipitating MeV electrons in the radiation belts. We then show that there exists a double resonance situation, by which, as an example, a wave is simultaneously in cyclotron resonance with 50 keV electrons as well as with 1.5 MeV electrons; the wave is first amplified by 50 keV electrons and then precipitates 1.5 MeV electrons. With the aid of the cyclotron resonance, the threshold field for the commencement of chaos in the electron trajectories is reduced considerably from that for a general case. Pitch angle scattering of 1.5 MeV electrons is demonstrated. The results show that a whistler wave with magnetic field amplitude of 0.08% of the background magnetic field can scatter electrons from an initial pitch angle of 86.5 deg. to a pitch angle <50 deg
Zheng, Ming; Chen, Fang-Yuan; Tian, Jia-Nan; Pan, Qing-Jiang
2018-03-21
To provide deep insight into cation-cation interactions (CCIs) involving hexavalent actinyl species that are major components in spent nuclear fuel and pose important implications for the effective removal of radiotoxic pollutants in the environment, a series of homo- and heterobimetallic actinide complexes supported by cyclopentadienyl (Cp) and polypyrrolic macrocycle (H 4 L) ligands were systematically investigated using relativistic density functional theory. The metal sort in both parts of (THF)(H 2 L)(OAn VI O) and (An') III Cp 3 from U to Np to Pu, as well as the substituent bonding to Cp from electron-donating Me to H to electron-withdrawing Cl, SiH 3 , and SiMe 3 , was changed. Over 0.70 electrons are unraveled to transfer from the electron-rich U III to the electron-deficient An VI of the actinyl moiety, leading to a more stable An V -U IV isomer; in contrast, uranylneptunium and uranylplutonium complexes behave as electron-resonance structures between VI-III and V-IV. These were further corroborated by geometrical and electronic structures. The energies of CCIs (i.e., O exo -An' bonds) were calculated to be -19.6 to -41.2 kcal/mol, affording those of OUO-Np (-23.9 kcal/mol) and OUO-Pu (-19.6 kcal/mol) with less electron transfer (ET) right at the low limit. Topological analyses of the electron density at the O exo -An' bond critical points demonstrate that the CCIs are ET or dative bonds in nature. A positive correlation has been built between the CCIs' strength and corresponding ET amount. It is concluded that the CCIs of O exo -An' are driven by the electrostatic attraction between the actinyl oxo atom (negative) and the actinide ion (positive) and enhanced by their ET. Finally, experimental syntheses of (THF)(H 2 L)(OU VI O)(An') III Cp 3 (An' = U and Np) were well reproduced by thermodynamic calculations that yielded negative free energies in a tetrahydrofuran solution but a positive one for their uranylplutonium analogue, which was synthetically
International Nuclear Information System (INIS)
Kato, K.G.; Benford, G.; Tzach, D.
1983-01-01
Prodigious quantities of microwave energy distributed uniformly across a wide frequency band are observed when a relativistic electron beam (REB) penetrates a plasma. Typical measured values are 20 MW total for Δνapprox. =40 GHz with preliminary observations of bandwidths as large as 100 GHz. An intense annular pulsed REB (Iapprox. =128 kA; rapprox. =3 cm; Δrapprox. =1 cm; 50 nsec FWHM; γapprox. =3) is sent through an unmagnetized or weakly magnetized plasma column (n/sub plasma/approx.10 13 cm -3 ). Beam-to-plasma densities of 0.01 >ω/sub p/ and weak harmonic structure is wholly unanticipated from Langmuir scattering or soliton collapse models. A model of Compton-like boosting of ambient plasma waves by the beam electrons, with collateral emission of high-frequency photons, qualitatively explains these spectra. Power emerges largely in an angle approx.1/γ, as required by Compton mechanisms. As n/sub b//n/sub p/ falls, ω/sub p/-2ω/sub p/ structure and harmonic power ratios consistent with soliton collapse theories appear. With further reduction of n/sub b//n/sub p/ only the ω/sub p/ line persists
International Nuclear Information System (INIS)
Sellem, F.
1997-01-01
This thesis is dedicated to the study of microwave radiation produced by relativistic electron beams. The vircator (virtual cathode oscillator) is a powerful microwave source based on this principle. This device is described but the complexity of the physical processes involved makes computer simulation necessary before proposing a simplified model. The existent M2V code has been useful to simulate the behaviour of a vircator but the representation of some phenomena such as hot points, the interaction of waves with particles lacks reliability. A new code CODEX has been written, it can solve Maxwell equations on a double mesh system by a finite difference method. The electric and magnetic fields are directly computed from the scalar and vectorial potentials. This new code has been satisfactorily tested on 3 configurations: the bursting of an electron beam in vacuum, the evolution of electromagnetic fields in diode and the propagation of waves in a wave tube. CODEX has been able to simulate the behaviour of a vircator, the frequency and power are well predicted and some contributions to the problem of origin of microwave production have been made. It seems that the virtual cathode is not directly involved in the microwave production. (A.C.)
International Nuclear Information System (INIS)
Shokair, I.R.
1991-01-01
Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z 2 for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs
Kolesnikov, E. K.; Manuilov, A. S.; Petrov, V. S.; Klyushnikov, G. N.; Chernov, S. V.
2017-06-01
The influence of the current neutralization process, the phase mixing of the trajectories of electrons and multiple Coulomb scattering of electrons beam on the atoms of the background medium on the spatial increment of the growth of sausage instability of a relativistic electron beam propagating in ohmic plasma channel has been considered. It has been shown that the amplification of the current neutralization leads to a significant increase in this instability, and phase mixing and the process of multiple scattering of electrons beam on the atoms of the background medium are the stabilizing factor.
Energy Technology Data Exchange (ETDEWEB)
Sahai, Aakash A., E-mail: aakash.sahai@gmail.com [Department of Electrical Engineering, Duke University, Durham, North Carolina 27708 (United States)
2014-05-15
We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime (a{sub 0}>1). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-β traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators. In Relativistically Induced Transparency Acceleration (RITA) scheme, the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparency through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme, the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. In RPA, the acceleration structure velocity critically depends upon plasma-ion mass in addition to the laser intensity and plasma density. In RITA, mass of the heavy immobile plasma-ions does not affect the speed of the critical layer. Inertia of the bared immobile ions in RITA excites the charge separation potential, whereas RPA is not possible when ions are stationary.
Sahai, Aakash A.
2014-05-01
We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime (a0>1). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-β traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators. In Relativistically Induced Transparency Acceleration (RITA) scheme, the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparency through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme, the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. In RPA, the acceleration structure velocity critically depends upon plasma-ion mass in addition to the laser intensity and plasma density. In RITA, mass of the heavy immobile plasma-ions does not affect the speed of the critical layer. Inertia of the bared immobile ions in RITA excites the charge separation potential, whereas RPA is not possible when ions are stationary.
Dal Lago, A.; Marchezi, J. P.; Alves, L. R.; da Silva, L.; Dallaqua, R.; Medeiros, C.; Souza, V. M. C. E. S.; Rockenbach, M.; Vieira, L.; Mendes, O., Jr.; Sibeck, D. G.; Kanekal, S. G.; Kletzing, C.; Baker, D. N.; Wygant, J. R.
2016-12-01
Various physical processes can contribute to loss and acceleration of energetic electrons in the Earth's radiation belts. In the range of 1 mHz to 10 Hz, ultra-low frequency (ULF) waves are known to cause significant changes in the energetic particle flux in the radiation belts. On board the Van Allen Probes, the Relativistic Electron Proton Telescope (REPT) measures the relativistic electron flux in the outer radiation belts in the energy range from 1.8 MeV up to 20 MeV. We selected events that have significant electron flux dropouts, classified into two categories regarding the time elapsed between the outer radiation belt dropout and the refurbishing, namely events that time scale had taken (i) a few hours and, (ii) some days. This work aims to investigate the presence of ULF waves using the radial and azimuthal magnetic and electric field components recorded by the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS). The evaluation of the power spectral density of those components unravels the poloidal and toroidal characteristc of the rapid compressional waves. We discuss how these modes can contribute to modifications of the relativistic electron fluxes considering the (i) and (ii) cases.
Energy Technology Data Exchange (ETDEWEB)
Ma, Tammy Yee Wing [Univ. of California, San Diego, CA (United States)
2010-01-01
The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.
Sarlanis, Christos; Heber, Bernd; Labrenz, Johannes; Kühl, Patrick; Marquardt, Johannes; Dimitroulakos, John; Papaioannou, Athanasios; Posner, Arik
2017-04-01
Solar Energetic Particle (SEP) events are one of the most important elements of space weather. Given that the complexity of the underlying physical processes of the acceleration and propagation of SEP events is still a very active research area, the prognosis of SEP event occurrence and their corresponding characteristics remains challenging. In order to provide up to an hour warning time before these particles arrive at Earth, relativistic electron and below 50 MeV proton data from the Electron Proton Helium Instrument (EPHIN) on SOHO were used to implement the 'Relativistic Electron Alert System for Exploration (REleASE)'. The REleASE forecasting scheme was recently rewritten in the open access programming language PYTHON and will be made publicly available. As a next step, along with relativistic electrons (v > 0.9 c) provided by SOHO, near-relativistic (v c) electron measurements from other instruments like the Electron Proton Alpha Monitor (EPAM) aboard the Advanced Composition Explorer (ACE) have been utilized. In this work, we demonstrate the real-time outputs derived by the end user from the REleASE using both SOHO/EPHIN and ACE/EPAM. We further, show a user friendly illustration of the outputs that make use of a "traffic light" to monitor the different warning stages: quiet, warning, alert offering a simple guidance to the end users. Finally, the capabilities offered by this new system, accessing both the pictorial and textural outputs REleASE are being presented. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.
International Nuclear Information System (INIS)
Takabayashi, Y.; Bagrov, V.G.; Bogdanov, O.V.; Pivovarov, Yu.L.; Tukhfatullin, T.A.
2015-01-01
New experiments on channeling of 255 MeV electrons in a half-wavelength crystals (HWC) were performed at SAGA Light Source facilities. The simulations of trajectories for (2 2 0) and (1 1 1) planar channeling in Si were performed using the computer code BCM-1.0. Comparison of experimental and theoretical results shows a good agreement. The results of calculations of spectral distribution of radiation in forward direction (θ = 0°) from 255 MeV electrons at (2 2 0) channeling in HWC silicon are presented. Qualitative comparison with radiation spectrum from an electron moving in an arc is performed
International Nuclear Information System (INIS)
Fink, J.; Schilling, H.B.; Schumacher, U.
1979-07-01
The experiments with a divided cathode in an electron beam gun, one half of which is connected via a resistor with the high voltage terminal, lead to the generation of a low emittance electron beam with instantaneously two different energies which is suitable for suppression of collective instabilities in an electron ring accelerator. The energy difference can be varied up to 100 keV proportional to the resistance, and the sub-currents are equal. The beam parts are well separated and focussed at the injection area of the compressor, and their radial distance is about equal to the radial difference of the corresponding closed orbits, such that electron ring formation with minimum radial betatron oscillations should be possible. (orig.)
Generation of an intense ion beam by a pinched relativistic electron beam
International Nuclear Information System (INIS)
Gilad, P.; Zinamon, Z.
1976-01-01
The pinched electron beam of a pulsed electron accelerator is used to generate an intense beam of ions. A foil anode and vacuum drift tube are used. The space charge field of the pinched beam in the tube accelerates ions from the foil anode. Ion currents of 10 kA at a density of 5kA/cm 2 with pulse length of 50 ns are obtained using a 5 kJ, 450 kV, 3 Ω diode. (author)
Solution of the Fokker-Planck equation for axially-channeled relativistic electrons
International Nuclear Information System (INIS)
Muralev, V.A.; Telegin, V.I.
1981-01-01
A method of the two dimensional kinetic equation of the Fokker-Planck type for axially-channeled electrons is proposed. This equation has been obtained recently by Beloshitsky and Kumakhov to describe the diffusion of channeling negative particles over the transverse energy and angular momentum. The results of computation of the dechanneling function of 1 GeV electrons in tungsten are presented. (author)
Strongly anisotropic spin-orbit splitting in a two-dimensional electron gas
DEFF Research Database (Denmark)
Michiardi, Matteo; Bianchi, Marco; Dendzik, Maciej
2015-01-01
Near-surface two-dimensional electron gases on the topological insulator Bi$_2$Te$_2$Se are induced by electron doping and studied by angle-resolved photoemission spectroscopy. A pronounced spin-orbit splitting is observed for these states. The $k$-dependent splitting is strongly anisotropic...
Energy Technology Data Exchange (ETDEWEB)
Amour, L. [Reims Univ., Lab. de Mathematiques EDPPM, FRE-CNRS 3111, 51 (France); Faupin, J. [Aarhus Univ., Institut for Matematiske Fag (Denmark); Grebert, B. [Nantes Univ, Lab. de Mathematiques Jean-Leray, UMR-CNRS 6629 (France); Guillot, J.C. [Ecole Polytechnique, Centre de Mathematiques Appliquees, UMR-CNRS 7641, 91 - Palaiseau (France)
2008-10-15
We consider a non-relativistic electron interacting with a classical magnetic field pointing along the x{sub 3}-axis and with a quantized electromagnetic field. The system is translation invariant in the x{sub 3}-direction and the corresponding Hamiltonian has a decomposition H {approx_equal}{integral}{sub R}{sup +}H(P{sub 3})dP{sub 3}. For a fixed momentum P{sub 3} sufficiently small, we prove that H(P{sub 3}) has a ground state in the Fock representation if and only if E'(P{sub 3})=0, where P{sub 3} {yields}E'(P{sub 3}) is the derivative of the map P{sub 3}{yields}E(P{sub 3})=inf{sigma}(H(P{sub 3})). If E'(P{sub 3}){ne}0, we obtain the existence of a ground state in a non-Fock representation. This result holds for sufficiently small values of the coupling constant. (authors)
Aryanpour, K.; Roberts, A.; Sandhu, A.; Rathore, R.; Shukla, A.; Mazumdar, S.
2013-01-01
Strong electron correlation effects in the photophysics of quasi-one-dimensional $\\pi$-conjugated organic systems such as polyenes, polyacetylenes, polydiacetylenes, etc., have been extensively studied. Far less is known on correlation effects in two-dimensional $\\pi$-conjugated systems. Here we present theoretical and experimental evidence for moderate repulsive electron-electron interactions in a number of finite polycyclic aromatic hydrocarbon molecules with $D_{6h}$ symmetry. We show that...
Goikhman, M. B.; Gromov, A. V.; Kovalev, N. F.; V. Palitsin, A.
2016-12-01
We consider the properties of thin-walled, strongly magnetized electron beams in closed evacuated transportation channels with arbitrary cross sections of the channel and the electron beam. Explicit precise formulas are obtained for the limiting and Fedosov's currents of such electron beams. The found relationships allow one to explain many observed phenomena and can serve as a basis for verification of the results of more complicated calculations.
Weakly relativistic plasma expansion
Energy Technology Data Exchange (ETDEWEB)
Fermous, Rachid, E-mail: rfermous@usthb.dz; Djebli, Mourad, E-mail: mdjebli@usthb.dz [Theoretical Physics Laboratory, Faculty of Physics, USTHB, B.P. 32 Bab-Ezzouar, 16079 Algiers (Algeria)
2015-04-15
Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.
Demianski, Marek
2013-01-01
Relativistic Astrophysics brings together important astronomical discoveries and the significant achievements, as well as the difficulties in the field of relativistic astrophysics. This book is divided into 10 chapters that tackle some aspects of the field, including the gravitational field, stellar equilibrium, black holes, and cosmology. The opening chapters introduce the theories to delineate gravitational field and the elements of relativistic thermodynamics and hydrodynamics. The succeeding chapters deal with the gravitational fields in matter; stellar equilibrium and general relativity
Directory of Open Access Journals (Sweden)
R. Kataoka
2008-06-01
Full Text Available We report average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit (GEO. It is found that seven of top ten extreme events at GEO during solar cycle 23 are associated with the magnetosphere inflation during the storm recovery phase as caused by the large-scale solar wind structure of very low dynamic pressure (<1.0 nPa during rapid speed decrease from very high (>650 km/s to typical (400–500 km/s in a few days. For the seven events, the solar wind parameters, geomagnetic activity indices, and relativistic electron flux and geomagnetic field at GEO are superposed at the local noon period of GOES satellites to investigate the physical cause. The average profiles support the "double inflation" mechanism that the rarefaction of the solar wind and subsequent magnetosphere inflation are one of the best conditions to produce the extreme flux enhancement at GEO because of the excellent magnetic confinement of relativistic electrons by reducing the drift loss of trapped electrons at dayside magnetopause.
Dynamics of valence-shell electrons and nuclei probed by strong-field holography and rescattering
Walt, Samuel G.; Bhargava Ram, Niraghatam; Atala, Marcos; Shvetsov-Shilovski, Nikolay I; von Conta, Aaron; Baykusheva, Denitsa; Lein, Manfred; Wörner, Hans Jakob
2017-01-01
Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales. These results offer perspectives for imaging ultrafast dynamics of molecules on femtosecond to attosecond timescales. PMID:28643771
Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam
International Nuclear Information System (INIS)
Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Wu, Jennifer W.
2008-01-01
Computer simulations using the 2D code 'POSINST' were used to study the formation of the electron cloud in the wiggler section of the positron damping ring of the International Linear Collider. In order to simulate an x-y slice of the wiggler (i.e., a slice perpendicular to the beam velocity), each simulation assumed a constant vertical magnetic field. At values of the magnetic field where the cyclotron frequency was an integral multiple of the bunch frequency, and where the field strength was less than approximately 0.6 T, equilibrium average electron densities were up to three times the density found at other neighboring field values. Effects of this resonance between the bunch and cyclotron frequency are expected to be non-negligible when the beam bunch length is much less than the product of the electron cyclotron period and the beam
Generation of a cold, intense relativistic electron beam using a magnetized foilless diode
International Nuclear Information System (INIS)
Sheffield, R.L.; Montgomery, M.D.; Parker, J.V.; Riepe, K.B.; Singer, S.
1982-01-01
An annular electron beam with less than 30 mrad of angular velocity spread, a radius of 1 cm, and a current density exceeding 0.4 MA/cm 2 has been generated with a magnetized foilless diode. The diode current loss is limited to less than a few percent by careful design of the tapered transition region connecting a self-magnetically insulated vacuum transmission line to the externally magnetized foilless diode. Details of the transition section design and operating characteristics of the electron beam generator are given
Notes on the relativistic movement of runaway electrons in parallel electric and magnetic fields
Czech Academy of Sciences Publication Activity Database
Delong, Vojtěch A.; Beňo, R.; Břeň, D.; Kulhánek, P.
2016-01-01
Roč. 23, č. 9 (2016), s. 1-4, č. článku 094504. ISSN 1070-664X R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : electrons * plasma * velociti * Larmor radius Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.115, year: 2016
Electron-positron pair production in relativistic ion-atom collisions
International Nuclear Information System (INIS)
Eichler, Joerg
2005-01-01
The creation of electron-positron pairs constitutes an example for the conversion of energy into mass. We here give a brief outline of the various processes and theoretical approaches in a simple fashion. We point out some recent results and difficulties that have yet to be overcome
Mainali, Laxman; Sahu, Indra; Earle, Keith
2008-03-01
Relativistic density functional theory calculations of electron paramagnetic resonance (EPR) parameters using a variety of basis sets have been computed for the model systems Vanadyl acetyl acetonate and Copper acetyl acetonate using the ORCA program. The basis set dependence of g and A tensor calculations for Vanadyl acetyl acetonate and Copper acetyl acetonate were studied using Pople Style and Ahlrichs basis sets in Local and gradient corrected functionals (BP86 and PWP) and Hybrid functionals (B3LYP and PW1PW). The PW1PW hybrid functional gives the best values for VO(acac)2 using the TZV basis set and for Cu(acac)2 using the 6-311G(d) basis set. The calculated A values with PW1PW hybrid functional for VO(acac)2 and Local and gradient corrected functional (BP86) for Cu(acac)2 with same basis set (DZ) give better results than previously reported values using the Amsterdam Density Functional Theory (ADF) Software. Our calculated g and A tensor values are in good agreement with the values determined from experiment.
Arabshahi, S.; Dwyer, J. R.; Nag, A.; Rakov, V. A.; Rassoul, H. K.
2014-01-01
Compact intracloud discharges (CIDs) are sources of the powerful, often isolated radio pulses emitted by thunderstorms. The VLF-LF radio pulses are called narrow bipolar pulses (NBPs). It is still not clear how CIDs are produced, but two categories of theoretical models that have previously been considered are the Transmission Line (TL) model and the Relativistic Runaway Electron Avalanche-Extensive Air Showers (RREA-EAS) model. In this paper, we perform numerical calculations of RREA-EASs for various electric field configurations inside thunderstorms. The results of these calculations are compared to results from the other models and to the experimental data. Our analysis shows that different theoretical models predict different fundamental characteristics for CIDs. Therefore, many previously published properties of CIDs are highly model dependent. This is because of the fact that measurements of the radiation field usually provide information about the current moment of the source, and different physical models with different discharge currents could have the same current moment. We have also found that although the RREA-EAS model could explain the current moments of CIDs, the required electric fields in the thundercloud are rather large and may not be realistic. Furthermore, the production of NBPs from RREA-EAS requires very energetic primary cosmic ray particles, not observed in nature. If such ultrahigh-energy particles were responsible for NBPs, then they should be far less frequent than is actually observed.
Schiller, Q.; Tu, W.; Ali, A. F.; Li, X.; Godinez, H. C.; Turner, D. L.; Morley, S. K.; Henderson, M. G.
2017-03-01
The most significant unknown regarding relativistic electrons in Earth's outer Van Allen radiation belt is the relative contribution of loss, transport, and acceleration processes within the inner magnetosphere. Detangling each individual process is critical to improve the understanding of radiation belt dynamics, but determining a single component is challenging due to sparse measurements in diverse spatial and temporal regimes. However, there are currently an unprecedented number of spacecraft taking measurements that sample different regions of the inner magnetosphere. With the increasing number of varied observational platforms, system dynamics can begin to be unraveled. In this work, we employ in situ measurements during the 13-14 January 2013 enhancement event to isolate transport, loss, and source dynamics in a one-dimensional radial diffusion model. We then validate the results by comparing them to Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms observations, indicating that the three terms have been accurately and individually quantified for the event. Finally, a direct comparison is performed between the model containing event-specific terms and various models containing terms parameterized by geomagnetic index. Models using a simple 3/Kp loss time scale show deviation from the event-specific model of nearly 2 orders of magnitude within 72 h of the enhancement event. However, models using alternative loss time scales closely resemble the event-specific model.
Observation of the Avalanche of Runaway Electrons in Air in a Strong Electric Field
Gurevich, A. V.; Mesyats, G. A.; Zybin, K. P.; Yalandin, M. I.; Reutova, A. G.; Shpak, V. G.; Shunailov, S. A.
2012-08-01
The generation of an avalanche of runaway electrons is demonstrated for the first time in a laboratory experiment. Two flows of runaway electrons are formed sequentially in an extended air discharge gap at the stage of delay of a pulsed breakdown. The first, picosecond, runaway electron flow is emitted in the cathode region where the field is enhanced. Being accelerated in the gap, this beam generates electrons due to impact ionization. These secondary electrons form a delayed avalanche of runaway electrons if the field is strong enough. The properties of the avalanche correspond to the existing notions about the runaway breakdown in air. The measured current of the avalanche exceeds up to an order the current of the initiating electron beam.
Density-dependent electron scattering in photoexcited GaAs in strongly diffusive regime
DEFF Research Database (Denmark)
Mics, Zoltán; D’Angio, Andrea; Jensen, Søren A.
2013-01-01
In a series of systematic optical pump–terahertz probe experiments, we study the density-dependent electron scattering rate in photoexcited GaAs in the regime of strong carrier diffusion. The terahertz frequency-resolved transient sheet conductivity spectra are perfectly described by the Drude...... model, directly yielding the electron scattering rates. A diffusion model is applied to determine the spatial extent of the photoexcited electron-hole gas at each moment after photoexcitation, yielding the time-dependent electron density, and hence the density-dependent electron scattering time. We find...... that the electron scattering time decreases from 320 to 60 fs, as the electron density changes from 1015 to 1019 cm−3....
Guasp, J.; Pastor, I.; Álvarez-Estrada, R. F.; Castejón, F.
2015-02-01
Analytical results obtained recently of the ab-initio classical incoherent Thomson Scattering (TS) spectrum from a single-electron (Alvarez-Estrada et al 2012 Phys. Plasmas 19 062302) have been numerically implemented in a paralelized code to efficiently compute the TS emission from a given electron distribution function, irrespective of its characteristics and/or the intensity of the incoming radiation. These analytical results display certain differences, when compared with other authors, in the general case of incoming linearly and circularly polarized radiation and electrons with arbitrary initial directions. We regard such discrepancies and the ubiquitous interest in TS as motivations for this work. Here, we implement some analytical advances (like generalized Bessel functions for incoming linearly polarized radiation) in TS. The bulk of this work reports on the efficient computation of TS spectra (based upon our analytical approach), for an electron population having an essentially arbitrary distribution function and for both incoming linearly and circularly polarized radiation. A detailed comparison between the present approach and a previous Monte Carlo one (Pastor et al 2011 Nuclear Fusion 51 043011), dealing with the ab-initio computation of TS spectra, is reported. Both approaches are shown to fully agree with each other. As key computational improvements, the analytical technique yields a × 30 to × 100 gain in computation time and is a very flexible tool to compute the scattered spectrum and eventually the scattered electromagnetic fields in the time domain. The latter are computed explicitly here for the first time, as far as we know. Scaling laws for the power integrated over frequency versus initial kinetic energy are studied for the case of isotropic and monoenergetic electron distribution functions and their potential application as diagnostic tools for high-energy populations is briefly discussed. Finally, we discuss the application of these
Khazanov, G. V.; Gallagher, D. L.; Gamayunov, K.
2007-01-01
It is well known that the effects of EMIC waves on RC ion and RB electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. Therefore, realistic characteristics of EMIC waves should be properly determined by modeling the RC-EMIC waves evolution self-consistently. Such a selfconsistent model progressively has been developing by Khaznnov et al. [2002-2006]. It solves a system of two coupled kinetic equations: one equation describes the RC ion dynamics and another equation describes the energy density evolution of EMIC waves. Using this model, we present the effectiveness of relativistic electron scattering and compare our results with previous work in this area of research.
Isochoric heating of reduced mass targets by ultra-intense laser produced relativistic electrons
Energy Technology Data Exchange (ETDEWEB)
Neumayer, P; Lee, H J; Offerman, D; Shipton, E; Kemp, A; Kritcher, A L; Doppner, T; Back, C A; Glenzer, S H
2009-02-04
We present measurements of the chlorine K-alpha emission from reduced mass targets, irradiated with ultra-high intensity laser pulses. Chlorinated plastic targets with diameters down to 50 micrometers and mass of a few 10{sup -8} g were irradiated with up to 7 J of laser energy focused to intensities of several 10{sup 19} W/cm{sup 2}. The conversion of laser energy to K-alpha radiation is measured, as well as high resolution spectra that allow observation of line shifts, indicating isochoric heating of the target up to 18 eV. A zero-dimensional 2-temperature equilibration model, combined with electron impact K-shell ionization and post processed spectra from collisional radiative calculations reproduces the observed K-alpha yields and line shifts, and shows the importance of target expansion due to the hot electron pressure.
Ion and relativistic electron acceleration by Alfven and whistler turbulence in solar flares
Miller, James A.; Ramaty, Reuven
1987-01-01
A model is proposed in which turbulent Alfven and whistler waves simultaneously produce the proton and electron spectra implied by the gamma-ray observations noted during the impulsive phase of the June 3, 1982 flare. The results demonstrate that protons can be accelerated to several GeV in less than about 10 sec by Alfven turbulence whose energy density is greater than a few erg/cu cm. It is also found that electrons may be accelerated to tens of MeV on similar time scales by whistler and Alfven turbulence. A lower limit on the energy density of the Alfven turbulence is obtained which is small compared to the total magnetic energy density.
Czech Academy of Sciences Publication Activity Database
Wagenknecht, David; Carva, K.; Turek, Ilja
2017-01-01
Roč. 53, č. 11 (2017), č. článku 1700205. ISSN 0018-9464 R&D Projects: GA ČR GA15-13436S Institutional support: RVO:68081723 Keywords : electronic transport * magnetic alloys * ab initio theory Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.243, year: 2016
New global loss model of energetic and relativistic electrons based on Van Allen Probes measurements
Ksenia Orlova; Yuri Shprits; Maria Spasojevic
2016-01-01
The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on the Van Allen Probes provides a vast quantity of fully resolved wave measurements below L = 5.5, a critical region for radiation belt acceleration and loss. EMFISIS data show that plasmaspheric hiss waves can be observed at frequencies as low as 20 Hz and provide three-component magnetic field measurements that can be directly used for electron scattering calculations. Updated models of hiss proper...
Cooray, G. V.; Cooray, G. K.
2011-12-01
Gurevich et al. [1] postulated that the source of narrow bipolar pulses, a class of high energy pulses that occur during thunderstorms, could be a runaway electron avalanche driven by the intense electric fields of a thunderstorm. Recently, Watson and Marshall [2] used the modified transmission line model to test the mechanism of the source of narrow bipolar pulses. In a recent paper, Cooray and Cooray [3] demonstrated that the electromagnetic fields of accelerating charges could be used to evaluate the electromagnetic fields from electrical discharges if the temporal and spatial variation of the charges in the discharge is known. In the present study, those equations were utilized to evaluate the electromagnetic fields generated by a relativistic electron avalanche. In the analysis it is assumed that all the electrons in the avalanche are moving with the same speed. In other words, the growth or the decay of the number of electrons takes place only at the head of the avalanche. It is shown that the radiation is emanating only from the head of the avalanche where electrons are being accelerated. It is also shown that an analytical expression for the radiation field of the avalanche at any distance can be written directly in terms of the e-folding length of the avalanche. This makes it possible to extract directly the spatial variation of the e-folding length of the avalanche from the measured radiation fields. In the study this model avalanche was used to investigate whether it can be used to describe the measured electromagnetic fields of narrow bipolar pulses. The results obtained are in reasonable agreement with the two station data of Eack [4] for speeds of propagation around (2 - 2.5) x 10^8 m/s and when the propagation effects on the electric fields measured at the distant station is taken into account. [1] Gurevich et al. (2004), Phys. Lett. A., 329, pp. 348 -361. [2] Watson, S. S. and T. C. Marshall (2007), Geophys. Res. Lett., Vol. 34, L04816, doi: 10
Characteristics of warm dense matter produced by a relativistic electron beam
Kwan, Thomas; Schmitt, Mark; Berninger, Michael
2009-11-01
Accurate equation-of-state theory on warm dense matter is a big challenge to model and good experimental data is difficult to obtain. One of the difficulties is the creation of a warm dense matter (WDM) suitable for experiments to examine its equation of state. We have performed calculations using MCNP and LASNEX to examine the warm dense matter created by a highly energetic electron beam such as the DARHT beam at LANL in a cylindrical sample confined by a collar. Energy deposition by the electron beam in the target and collar of different materials were calculated with different beam profiles. The energy deposition was sourced into LASNEX calculations to examine the dynamic evolution of the target and the generation of radially outward propagating shock waves. Our calculations indicated warm dense matter with a temperature of a few electron volts is achievable and the speed of the shock wave can be determined using photonic Doppler velocimetry technique. We will present results from our calculations for various materials of the target and collar and in different geometries.
International Nuclear Information System (INIS)
Aleinik, A.N.; Chefonov, O.V.; Kalinin, B.N.; Naumenko, G.A.; Potylitsyn, A.P.; Saruev, G.A.; Sharafutdinov, A.F.
2003-01-01
The resonant optical polarization radiation (ROPR) in the Smith-Purcell geometry and the one from the inclined grating at the Tomsk synchrotron and 6-MeV microtron have been investigated. The polarization radiation was observed at 4.2 deg. from the 200 MeV electron beam and at 5 deg. from the 6.2 MeV electron beam. Two methods of measurement of ROPR maxima in these two cases have been used. In the first case (the experiment on synchrotron) we have fixed the wavelength of radiation using an optical filter; the orientation dependence of this radiation was measured. In this dependence we have observed two peaks of radiation from electrons in gold foil grating of 0.1 mm period. The first large peak is a zeroth order peak in direction of specular reflection, and the second one is the first-order peak of resonant polarization radiation. In the experiment on microtron the spectra of ROPR from aluminum foil strip grating of 0.2 mm period in the Smith-Purcell geometry were measured, and the peak of the first-order Smith-Purcell radiation in these spectra was observed. The comparison of data obtained with the simulation results has been performed
A long-lived relativistic electron storage ring embedded in Earth's outer Van Allen belt.
Baker, D N; Kanekal, S G; Hoxie, V C; Henderson, M G; Li, X; Spence, H E; Elkington, S R; Friedel, R H W; Goldstein, J; Hudson, M K; Reeves, G D; Thorne, R M; Kletzing, C A; Claudepierre, S G
2013-04-12
Since their discovery more than 50 years ago, Earth's Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for more than 4 weeks before being disrupted (and virtually annihilated) by a powerful interplanetary shock wave passage.
Monochromatic coherent transition and diffraction radiation from a relativistic electron bunch train
Naumenko, G.; Potylitsyn, A.; Shevelev, M.; Karataev, P.; Shipulya, M.; Bleko, V.
2018-04-01
Electron beams of most accelerators have a bunched structure and are synchronized with the accelerating RF field. Due to modulation of the electron beam with frequency ν RF one can expect to observe resonances with frequencies ν k=kṡ ν RF in radiation spectrum generated via any spontaneous emission mechanism (k is an integer and the resonance order). In this paper we present the results of spectral measurements of coherent transition radiation (CTR) generated by an electron bunch train from the Tomsk microtron with ν RF=2.63GHz in the spectral frequency range from 8 to 35 GHz. We also measured the spectrum of coherent diffraction radiation and demonstrated that the observed spectra in both cases consist of monochromatic lines. For spectral measurements the Martin-Puplett interferometer with spectral resolution of 800 MHz (FWMH) was employed. Using a waveguide frequency cut-off we were able to exclude several spectral lines to observe higher resonance orders of up to k =7.
International Nuclear Information System (INIS)
Multiple scale methods are used to treat several ingredients of the theory of atoms in strong electromagnetic fields. First, a focused electromagnetic field is expanded. Second, a classical electron is described giving the ponderomotive potential. Third, the quantum electron is treated in the WKB approximation. Fourth, the one dimensional quantum harmonic oscillator is solved; and last the one dimensional square well, showing the low intensity limit of the theory
International Nuclear Information System (INIS)
Lemons, Don S.
2012-01-01
We develop a Markov process theory of charged particle scattering from stationary, transverse, magnetic waves. We examine approximations that lead to quasilinear theory, in particular the resonant diffusion approximation. We find that, when appropriate, the resonant diffusion approximation simplifies the result of the weak turbulence approximation without significant further restricting the regime of applicability. We also explore a theory generated by expanding drift and diffusion rates in terms of a presumed small correlation time. This small correlation time expansion leads to results valid for relatively small pitch angle and large wave energy density - a regime that may govern pitch angle scattering of high-energy electrons into the geomagnetic loss cone.
Kinetic magnetization by fast electrons in laser-produced plasmas at sub-relativistic intensities
Czech Academy of Sciences Publication Activity Database
Pisarczyk, T.; Gus'kov, S. Yu.; Chodukowski, T.; Dudžák, Roman; Korneev, Ph.; Demchenko, N. N.; Kalinowska, Z.; Dostál, Jan; Zaras-Szydlowska, A.; Borodziuk, S.; Juha, Libor; Cikhardt, Jakub; Krása, Josef; Klír, Daniel; Cikhardtová, B.; Kubeš, P.; Krouský, Eduard; Krůs, Miroslav; Ullschmied, Jiří; Jungwirth, Karel; Hřebíček, Jan; Medřík, Tomáš; Golasowski, Jiří; Pfeifer, Miroslav; Renner, Oldřich; Singh, Sushil K.; Kar, S.; Ahmed, H.; Skála, Jiří; Pisarczyk, P.
2017-01-01
Roč. 24, č. 10 (2017), s. 1-11, č. článku 102711. ISSN 1070-664X R&D Projects: GA MŠk EF15_008/0000162 EU Projects: European Commission(XE) 654148 - LASERLAB-EUROPE Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : laser-produced plasma * femtosecond polaro-interferometry * spontaneous magnetic fiel * spatial and temporal electron density distribution Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.115, year: 2016
Czech Academy of Sciences Publication Activity Database
Breneman, A. W.; Crew, A.; Sample, J.; Klumpar, D.; Johnson, A.; Agapitov, O.; Shumko, M.; Turner, D. L.; Santolík, Ondřej; Wygant, J. R.; Cattell, C. A.; Thaller, S. A.; Blake, B.; Spence, H.; Kletzing, C. A.
2017-01-01
Roč. 44, č. 22 (2017), s. 11265-11272 ISSN 0094-8276 R&D Projects: GA ČR GA17-07027S Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : VLF-CHORUS * RADIATION BELT * ZONE ELECTRONS * SOURCE REGION * AURORAL-ZONE * GEM STORMS * PRECIPITATION * ASSOCIATION * RESOLUTION * EMISSIONS Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 4.253, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2017GL075001/epdf
International Nuclear Information System (INIS)
Ullschmied, J.; Simek, M.; Kolacek, K.; Ripa, M.
1996-01-01
Theoretical and experimental parameters characterizing the Langmuir turbulence in the REBEX machine are summarized. The experimental data collected up to now support the idea that at the end of the beam injection the beam-heated plasma in the REBEX machine reaches a strongly turbulent state. Nevertheless the attempts to determine the turbulence level on the base of spectroscopic measurements were unsuccessful up to now. From this point of view, the advantages and disadvantages of three different spectroscopic apparatuses used for detailed measurements of the profiles of hydrogen emission lines are discussed. (J.U.). 2 tabs., 5 figs., 13 refs
Relativistic electron influence on sanitary-model microorganisms and antibiotics in model samples
International Nuclear Information System (INIS)
Antipov, V.S.; Berezhna, I.V.; Kovpik, O.F.; Babych, E.M.; Voliansky, Yu.L.; Sklar, N.I.
2004-01-01
A series of the investigations of the electron beam influence on sanitary-model test cultures and antibiotics in model solutions has been carried out. For each of the test objects, the authors have found the boundary doses of the absorbed radiation. The higher doses cause the sharp increase in the bactericidal influence, which becomes complete. The sanitary-bactericidal indices of the water samples remain sable during 6 days. The samples of antibiotics in various concentrations (from 100 UA) have been irradiated. It is proved that the substratum processing by the beam (in the regimes 30 kGy) causes diminution and complete neutralization of the antibacterial activity in all probes of the samples
X-ray streak camera for observation of tightly pinched relativistic electron beams
International Nuclear Information System (INIS)
Johnson, D.J.
1977-01-01
A pinhole camera is coupled with a Pilot-B scintillator and image-intensified TRW streak camera to study pinched electron beam profiles via observation of anode target bremsstrahlung. Streak intensification is achieved with an EMI image intensifier operated at a gain of up to 10 6 which allows optimizing the pinhole configuration so that resolution is simultaneously limited by photon-counting statistics and pinhole geometry. The pinhole used is one-dimensional and is fabricated by inserting uranium shims with hyperbolic curved edges between two 5-cm-thick lead blocks. The loss of spatial resolution due to the x-ray transmission through the perimeter of the pinhole is calculated and a streak photograph of a Gamble I pinched beam interacting with a brass anode is presented
Prus, O.; Yaish, Y.; Reznikov, M.; Sivan, U.; Pudalov, V.
2002-01-01
A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances the low temperature susceptibility up to 7.5 folds compared with the Pauli susceptibility of non-interacting electrons. The magnetization peaks in the vicinity of the density where transition to strong localization takes place. At the same density, the suscep...
Perturbation theory of strongly correlated electrons with and without slave boson technique
International Nuclear Information System (INIS)
Nguyen Van Hieu; Ha Vinh Tan; Nguyen Toan Thang; Nguyen Ai Viet.
1988-10-01
The Green functions of the electrons in the two-band Hubbard model with the strong on-site Coulomb repulsion were calculated by means of the perturbation theory with respect to the hopping term of the Hamiltonian. It was shown that in the slave boson technique we obtain the expressions different from the results of the calculations involving directly electron operators without using slave bosons. The physical meaning of this discrepancy was discussed. (author)
Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Liu, Yaqi; Xu, Jun; Yu, Dapeng; Wan, Weishi; Zhu, Yimei; Xiang, Dao; Zhang, Jie
2018-03-01
An accelerator-based MeV ultrafast electron microscope (MUEM) has been proposed as a promising tool to the study structural dynamics at the nanometer spatial scale and the picosecond temporal scale. Here, we report experimental tests of a prototype MUEM where high quality images with nanoscale fine structures were recorded with a pulsed ˜3 MeV picosecond electron beam. The temporal and spatial resolutions of the MUEM operating in the single-shot mode are about 4 ps (FWHM) and 100 nm (FWHM), corresponding to a temporal-spatial resolution of 4 × 10-19 s m, about 2 orders of magnitude higher than that achieved with state-of-the-art single-shot keV UEM. Using this instrument, we offer the demonstration of visualizing the nanoscale periodic spatial modulation of an electron beam, which may be converted into longitudinal density modulation through emittance exchange to enable production of high-power coherent radiation at short wavelengths. Our results mark a great step towards single-shot nanometer-resolution MUEMs and compact intense x-ray sources that may have widespread applications in many areas of science.
Sofer, Zdeněk; Sedmidubský, David; Huber, Štěpán; Luxa, Jan; Bouša, Daniel; Boothroyd, Chris; Pumera, Martin
2016-03-01
Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer- and inner-sphere molecular probes is highly anisotropic. The electron-transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J.C.; Erickson, P. J.; Fennell, Joseph; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.;
2016-01-01
Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (Disturbance Storm Time Ring Current Index) value reaching 223 nanoteslas. On 22 June 2015 another strong storm (Dst reaching 204 nanoteslas) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E (Energy) greater than or approximately equal to 1 millielectronvolt) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 millielectronvolts in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong butterfly distributions with deep minima in flux at alpha equals 90 degrees. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported impenetrable barrier at L (L-shell magnetic field line value) approximately equal to 2.8 was pushed inward, but not significantly breached, and no E (Energy) greater than or approximately equal to 2.0 millielectronvolts electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.
Baker, D N; Jaynes, A N; Kanekal, S G; Foster, J C; Erickson, P J; Fennell, J F; Blake, J B; Zhao, H; Li, X; Elkington, S R; Henderson, M G; Reeves, G D; Spence, H E; Kletzing, C A; Wygant, J R
2016-07-01
Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm ( Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy ( E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong "butterfly" distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported "impenetrable barrier" at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.
International Nuclear Information System (INIS)
Hencken, K.; Trautmann, D.; Baur, G.
1995-01-01
We calculate the impact-parameter-dependent total probability P total (b) for the electromagnetic production of electron-positron pairs in relativistic heavy-ion collisions in lowest order. We study expecially impact parameters smaller than the Compton wavelength of the electron, where the equivalent-photon approximation cannot be used. Calculations with and without a form factor for the heavy ions are done; the influence is found to be small. The lowest-order results are found to violate unitarity and are used for the calculation of multiple-pair production probabilities with the help of the approximate Poisson distribution already found in earlier publications
Directory of Open Access Journals (Sweden)
Zhen Wang
2014-09-01
Full Text Available A new scheme to generate narrow-band tunable terahertz (THz radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme are demonstrated numerically with a start-to-end simulation using the beam parameters at the Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV. The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear rf chirp and longitudinal space charge effect have also been studied in our article. The methods to generate the THz radiation in SDUV with the new scheme and the estimation of the radiation power are also discussed briefly.
International Nuclear Information System (INIS)
Weidman, D.J.; Murphy, D.P.; Myers, M.C.; Meger, R.A.
1994-01-01
The expansion of the radius of a 5 MeV, 20 kA, 40 ns electron beam from SuperIBEX during propagation through gas is being measured. The beam is generated, conditions, equilibrated, and then passed through a thin foil that produces Cherenkov light, which is recorded by a streak camera. At a second location, the beam hits another Cherenkov emitter, which is viewed by a framing camera. Measurements at these two locations can provide a time-resolved measure of the beam expansion. The two measurements, however, must be synchronized with each other, because the beam radius is not constant throughout the pulse due to variations in beam current and energy. To correlate the timing of the two diagnostics, several shots have been taken with both diagnostics viewing Cherenkov light from the same foil. Experimental measurements of the Cherenkov light from one foil viewed by both diagnostics will be presented to demonstrate the feasibility of correlating the diagnostics with each other. Streak camera data showing the optical fiducial, as well as the final correlation of the two diagnostics, will also be presented. Preliminary beam radius measurements from Cherenkov light measured at two locations will be shown
Tian, Justin; Wang, Xu; Eberly, J. H.
2017-05-01
The lack of analytical solutions for the exit momentum in the laser-driven tunneling theory is a well-recognized problem in strong field physics. Theoretical studies of electron momentum distributions in the neighborhood of the tunneling exit depend heavily on ad hoc assumptions. In this Letter, we apply a new numerical method to study the exiting electron's longitudinal momentum distribution under intense short-pulse laser excitation. We present the first realizations of the dynamic behavior of an electron near the so-called tunneling exit region without adopting a tunneling approximation.
Electron cyclotron maser instability (ECMI in strong magnetic guide field reconnection
Directory of Open Access Journals (Sweden)
R. A. Treumann
2017-08-01
Full Text Available The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is
Electron cyclotron maser instability (ECMI) in strong magnetic guide field reconnection
Treumann, Rudolf A.; Baumjohann, Wolfgang
2017-08-01
The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales) electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR) in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects) involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is of particular
Density functional theory for strongly-interacting electrons: Perspectives for Physics and Chemistry
Gori Giorgi, P.; Seidl, M.
2010-01-01
Improving the accuracy and thus broadening the applicability of electronic density functional theory (DFT) is crucial to many research areas, from material science, to theoretical chemistry, biophysics and biochemistry. In the last three years, the mathematical structure of the strong-interaction
Strongly Correlated Electron Systems in The Half Filled Band of The ...
African Journals Online (AJOL)
Strong correlation of interacting electrons has been widely studied under the single band Hubbard model with the aid of several techniques. These numerous studies have been carried out at different band filling. In this work, the ground state properties in the half filled band in one dimension are studied employing a ...
Relativistic configuration interaction approach
Indian Academy of Sciences (India)
(and requirement for) ab-initio calculation of electronic structure providing a high level of reliability and accuracy in accounting for both relativistic and correlation effects associated with these properties has gained importance. In this paper, we will compute one of the P, T-odd interaction constants, the so-called Wd, which is.
Katsavrias, Christos; Daglis, Ioannis A.; Li, Wen; Dimitrakoudis, Stavros; Georgiou, Marina; Papadimitriou, Constantinos
2017-04-01
We present electron phase space density (PSD) calculations as well as concurrent Pc5 and chorus wave activity observations in the outer radiation belt during 18 intense geospace magnetic storms by employing multi-point particle and field observations (both in-situ and through ground-based remote sensing), including the THEMIS, Van Allen Probes, NOAA POES and GOES constellations, the XMM and INTEGRAL spacecraft, and the CARISMA and IMAGE ground magnetometer arrays. The data provide a broad range of particle energies and a wide radial and azimuthal spatial coverage. Observations show that different acceleration and loss mechanisms act simultaneously on different electron populations, depending on the values of the electrons' 1st and 2nd adiabatic invariants. This work has been supported by the NOA/IAASARS SOLPLA project.
Strong-coupling behaviour of two t - J chains with interchain single-electron hopping
International Nuclear Information System (INIS)
Zhang Guangming; Feng Shiping; Yu Lu.
1994-01-01
Using the fermion-spin transformation to implement spin-charge separation of constrained electrons, a model of two t - J chains with interchain single-electron hopping is studied by abelian bosonization. After spin-charge decoupling the charge dynamics can be trivially solved, while the spin dynamics is determined by a strong-coupling fixed point where the correlation functions can be calculated explicitly. This is a generalization of the Luther-Emery line for two-coupled t - J chains. The interchain single-electron hopping changes the asymptotic behaviour of the interchain spin-spin correlation functions and the electron Green function, but their exponents are independent of the coupling strength. (author). 25 refs
Tsurutani, B. T.; Hajra, R.; Tanimori, T.; Takada, A.; Bhanu, R.; Mannucci, A. J.; Lakhina, G. S.; Kozyra, J. U.; Shiokawa, K.; Lee, L. C.; Echer, E.; Reddy, R. V.; Gonzalez, W. D.
2016-10-01
A new scenario is presented for the cause of magnetospheric relativistic electron decreases (REDs) and potential effects in the atmosphere and on climate. High-density solar wind heliospheric plasmasheet (HPS) events impinge onto the magnetosphere, compressing it along with remnant noon-sector outer-zone magnetospheric 10-100 keV protons. The betatron accelerated protons generate coherent electromagnetic ion cyclotron (EMIC) waves through a temperature anisotropy (T⊥/T|| > 1) instability. The waves in turn interact with relativistic electrons and cause the rapid loss of these particles to a small region of the atmosphere. A peak total energy deposition of 3 × 1020 ergs is derived for the precipitating electrons. Maximum energy deposition and creation of electron-ion pairs at 30-50 km and at climate change mechanisms. Wilcox et al. (1973) noted a correlation between solar wind heliospheric current sheet (HCS) crossings and high atmospheric vorticity centers at 300 mb altitude. Tinsley et al. has constructed a global circuit model which depends on particle precipitation into the atmosphere. Other possible scenarios potentially affecting weather/climate change are also discussed.
Kovács, Z.; Harko, T.
2011-11-01
We present a full general relativistic numerical code for estimating the energy-momentum deposition rate (EMDR) from neutrino pair annihilation (?). The source of the neutrinos is assumed to be a neutrino-cooled accretion disc around neutron and quark stars. We calculate the neutrino trajectories by using a ray-tracing algorithm with the general relativistic Hamilton's equations for neutrinos and derive the spatial distribution of the EMDR due to the annihilations of neutrinos and antineutrinos around rotating neutron and quark stars. We obtain the EMDR for several classes of rotating neutron stars, described by different equations of state of the neutron matter, and for quark stars, described by the Massachusetts Institute of Technology (MIT) bag model equation of state and in the colour-flavour-locked (CFL) phase. The distribution of the total annihilation rate of the neutrino-antineutrino pairs around rotating neutron and quark stars is studied for isothermal discs and accretion discs in thermodynamical equilibrium. We demonstrate both the differences in the equations of state for neutron and quark matter and rotation with the general relativistic effects significantly modify the EMDR of the electrons and positrons generated by the neutrino-antineutrino pair annihilation around compact stellar objects, as measured at infinity.
Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas
Energy Technology Data Exchange (ETDEWEB)
Tierno, S. P., E-mail: sp.tierno@upm.es; Donoso, J. M.; Domenech-Garret, J. L.; Conde, L. [Department of Applied Physics, E.T.S.I. Aeronáutica y del Espacio. Universidad Politécnica de Madrid, 28040 Madrid (Spain)
2016-01-15
The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.
Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas
Tierno, S. P.; Donoso, J. M.; Domenech-Garret, J. L.; Conde, L.
2016-01-01
The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.
Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems
International Nuclear Information System (INIS)
Paolasini, L.; Bergevin, F. de
2008-01-01
Resonant X-ray scattering is a method which combines high-Q resolution X-ray elastic diffraction and atomic core-hole spectroscopy for investigating electronic and magnetic long-range ordered structures in condensed matter. During recent years the development of theoretical models to describe resonant X-ray scattering amplitudes and the evolution of experimental techniques, which include the control and analysis of linear photon polarization and the introduction of extreme environment conditions such as low temperatures, high magnetic field and high pressures, have opened a new field of investigation in the domain of strongly correlated electron systems. (authors)
International Nuclear Information System (INIS)
Vugman, N.V.
1973-08-01
The radiation effects in ]Ir III (CN) 6 ] 3- diamagnetic complexe inserted in the KCl lattice and irradiated with electrons of 2MeV by electron spin resonance (ESR) are analysed. Formulas for g and A tensors in the ligand field approximation, are derivated to calculate non coupling electron density in the metal. The X polarization field of inner shells is positive, indicating a 6s function mixture in the non coupling electron molecular orbital. The observed hyperfine structure is assigned to 4 equivalent nitrogen and one non equivalent nitrogen. This hypothesis is verified by experience of isotope substitution with 15 N. The s and p spin density in ligands are calculated and discussed in terms of molecular obitals. The effects of strong quadrupole interaction into the EPR spectra of ]Ir II (CN) 5 ] 3- complex are analysed by MAGNSPEC computer program to diagonalize the Spin Hamiltonian of the system. Empiric rules for EPR espectrum interpretation with strong quadrupole interaction. A review of EPR technique and a review of main concepts of crystal-field and ligand field theories, are also presented. (M.C.K.) [pt
Greenman, Loren; Mazziotti, David A
2010-10-28
Dioxetanone, a key component of the bioluminescence of firefly luciferin, is itself a chemiluminescent molecule due to two conical intersections on its decomposition reaction surface. While recent calculations of firefly luciferin have employed four electrons in four active orbitals [(4,4)] for the dioxetanone moiety, a study of dioxetanone [F. Liu et al., J. Am. Chem. Soc. 131, 6181 (2009)] indicates that a much larger active space is required. Using a variational calculation of the two-electron reduced-density-matrix (2-RDM) [D. A. Mazziotti, Acc. Chem. Res. 39, 207 (2006)], we present the ground-state potential energy surface as a function of active spaces from (4,4) to (20,17) to determine the number of molecular orbitals required for a correct treatment of the strong electron correlation near the conical intersections. Because the 2-RDM method replaces exponentially scaling diagonalizations with polynomially scaling semidefinite optimizations, we readily computed large (18,15) and (20,17) active spaces that are inaccessible to traditional wave function methods. Convergence of the electron correlation with active-space size was measured with complementary RDM-based metrics, the von Neumann entropy of the one-electron RDM as well as the Frobenius and infinity norms of the cumulant 2-RDM. Results show that the electron correlation is not correctly described until the (14,12) active space with small variations present through the (20,17) space. Specifically, for active spaces smaller than (14,12), we demonstrate that at the first conical intersection, the electron in the σ(∗) orbital of the oxygen-oxygen bond is substantially undercorrelated with the electron of the σ orbital and overcorrelated with the electron of the carbonyl oxygen's p orbital. Based on these results, we estimate that in contrast to previous treatments, an accurate calculation of the strong electron correlation in firefly luciferin requires an active space of 28 electrons in 25 orbitals
Extended Aharonov-Bohm period analysis of strongly correlated electron systems
Arita, Ryotaro; Kusakabe, Koichi; Kuroki, Kazuhiko; Aoki, Hideo
1996-01-01
The `extended Aharonov-Bohm (AB) period' recently proposed by Kusakabe and Aoki [J. Phys. Soc. Jpn (65), 2772 (1996)] is extensively studied numerically for finite size systems of strongly correlated electrons. While the extended AB period is the system length times the flux quantum for noninteracting systems, we have found the existence of the boundary across which the period is halved or another boundary into an even shorter period on the phase diagram for these models. If we compare this r...
Truncated exponential-rigid-rotor model for strong electron and ion rings
International Nuclear Information System (INIS)
Larrabee, D.A.; Lovelace, R.V.; Fleischmann, H.H.
1979-01-01
A comprehensive study of exponential-rigid-rotor equilibria for strong electron and ion rings indicates the presence of a sizeable percentage of untrapped particles in all equilibria with aspect-ratios R/a approximately <4. Such aspect-ratios are required in fusion-relevant rings. Significant changes in the equilibria are observed when untrapped particles are excluded by the use of a truncated exponential-rigid-rotor distribution function. (author)
Gain length fitting formula for free-electron lasers with strong space-charge effects
Directory of Open Access Journals (Sweden)
G. Marcus
2011-08-01
Full Text Available We present a power-fit formula, obtained from a variational analysis using three-dimensional free-electron laser theory, for the gain length of a high-gain free-electron laser’s fundamental mode in the presence of diffraction, uncorrelated energy spread, and longitudinal space-charge effects. The approach is inspired by the work of Xie [Nucl. Instrum. Methods Phys. Res., Sect. A 445, 59 (2000NIMAER0168-900210.1016/S0168-9002(0000114-5], and provides a useful shortcut for calculating the gain length of the fundamental Gaussian mode of a free-electron laser having strong space-charge effects in the 3D regime. The results derived from analytic theory are in good agreement with detailed numerical particle simulations that also include higher-order space-charge effects, supporting the assumptions made in the theoretical treatment and the variational solutions obtained in the single-mode limit.
Characteristics of electron emission from PZT ferroelectric cathode under strong accelerating field
Energy Technology Data Exchange (ETDEWEB)
Hayashi, Yasushi [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan)]. E-mail: hayashi@es.titech.ac.jp; Hotta, Eiki [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan); Flechtner, Donald [High Voltage Laboratory, Cornell University, Ithaca, NY (United States)
2002-02-07
We have studied emission characteristics of a PZT ferroelectric cathode under the influence of a strong accelerating field by varying the triggering conditions. The beam current pulse reveals a rising and a steady phase. In the rising phase, the time variation of the beam current is found to be linearly dependent on both the trigger voltage and the diode voltage at the time when the current starts. In the steady phase, field emission characteristics are observed. The results show that the diode voltage is not only accelerating the emitted electrons but also assisting the electron emission from the ferroelectric cathode. An empirical model is proposed and is found to yield a reasonable beam current pulse when the electric field on the surface of the cathode is uniformly distributed. It also provides us with a new possibility to diagnose the emission process of a ferroelectric electron gun. (author)
Alekseev, P. A.; Menushenkov, A. P.; Mignot, J.-M.; Nemkovski, K. S.; Yaroslavtsev, A. A.; Kozlenko, D. P.
Rare-earth based strongly correlated electron systems (SCES) exhibit a large variety of different ground states, ranging from the simple paramagnetism of crystal-field-split f-electron multiplets to highly unconventional Kondo-insulator states with a combination of charge gap, spin gap and valence instability, in which long-range magnetic order can eventually arise from an initially singlet state. The physical background for these properties of the electron subsystem may be clarified by performing detailed neutron scattering experiments, namely magnetic neutron scattering spectroscopy and diffraction. This report reviews the results of the previous and new experimental studies on a number of rare-earth intermetallic compounds, which shed light on peculiar features of those unusual ground states.
Luciano, Rezzolla
2013-01-01
Relativistic hydrodynamics is a very successful theoretical framework to describe the dynamics of matter from scales as small as those of colliding elementary particles, up to the largest scales in the universe. This book provides an up-to-date, lively, and approachable introduction to the mathematical formalism, numerical techniques, and applications of relativistic hydrodynamics. The topic is typically covered either by very formal or by very phenomenological books, but is instead presented here in a form that will be appreciated both by students and researchers in the field. The topics covered in the book are the results of work carried out over the last 40 years, which can be found in rather technical research articles with dissimilar notations and styles. The book is not just a collection of scattered information, but a well-organized description of relativistic hydrodynamics, from the basic principles of statistical kinetic theory, down to the technical aspects of numerical methods devised for the solut...
Directory of Open Access Journals (Sweden)
F. Liu
2012-07-01
Full Text Available The nonlinear Thomson scattering of a relativistic electron with an intense laser pulse is calculated numerically. The results show that an ultrashort x-ray pulse can be generated by an electron with an initial energy of 5 MeV propagating across a circularly polarized laser pulse with a duration of 8 femtosecond and an intensity of about 1.1×10^{21} W/cm^{2}, when the detection direction is perpendicular to the propagation directions of both the electron and the laser beam. The optimal values of the carrier-envelop phase and the intensity of the laser pulse for the generation of a single ultrashort x-ray pulse are obtained and verified by our calculations of the radiation characteristics.
Nonadiabaticity of electron-tunneling-ionization processes in elliptical strong laser fields
Cai, Jun; Chen, Yan-jun; Xia, Qin-zhi; Ye, Di-fa; Liu, Jie; Fu, Li-bin
2017-09-01
We theoretically investigate the electron-tunneling process for a helium atom irradiated by an elliptical strong laser field. The momentum distribution for an electron ionized during the cycle when the laser intensity reaches its maximum is captured, such that we can ignore the interference between the wave packets ionized in different laser cycles and precisely determine the center of the momentum distribution. The quantum mechanical prediction of the center position is further compared to the semiclassical single-trajectory simulation as well as the experimental data. We find that the electron momentums along the minor axis of the laser polarization show good agreement with the nonadiabatic semiclassical calculation for a wide range of laser intensities, indicating the existence of a nonzero lateral momentum when the electron exits the barrier. On the other hand, the offset angles obtained by our quantum mechanical approach for different laser intensities are larger than the nonadiabatic semiclassical results, indicating the importance of the quantum effects during the electron's under-the-barrier dynamics.
High Hole-Mobility Molecular Layer Made from Strong Electron Acceptor Molecules with Metal Adatoms.
Yamane, Hiroyuki; Kosugi, Nobuhiro
2017-11-02
The electronic structure of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-TCNQ (F 4 TCNQ) monolayers on Au(111) has been investigated by means of angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation. In contrast to the physisorbed TCNQ/Au(111) interface, the high-resolution core-level photoemission spectra and the low-energy electron diffraction at the F 4 TCNQ/Au(111) interface show evidence for the strong charge transfer (CT) from Au to F 4 TCNQ and for the Au atom segregation from the underlying Au(111) surface, suggesting a possible origin of the spontaneous formation of the two-dimensional F 4 TCNQ-Au network. The ARPES experiment reveals a low hole-injection barrier and large band dispersion in the CT-induced topmost valence level of the F 4 TCNQ-Au network with 260 meV bandwidth due to the adatom-mediated intermolecular interaction. These results indicate that strong electron acceptor molecules with metal adatoms can form high hole-mobility molecular layers by controlling the molecule-metal ordered structure and their CT interaction.
International Nuclear Information System (INIS)
Bastero-Gil, M.
2015-01-01
Relativistic cosmology is nothing but the study of the evolution of our universe expanding from the General Theory of Relativity, which describes the gravitational interaction at any scale and given its character far-reaching is the force that dominate the evolution of the universe. (Author)
Price, R H
1993-01-01
Work reported in the workshop on relativistic astrophysics spanned a wide varicy of topics. Two speciﬁc areas seemed of particular interest. Much attention was focussed on gravitational wave sources, especially on the waveforms they produce, and progress was reported in theoretical and observational aspects of accretion disks.
Critical Behavior of a Strongly-Interacting 2D Electron System
Sarachik, Myriam P.
2013-03-01
Two-dimensional (2D) electron systems that obey Fermi liquid theory at high electron densities are expected to undergo one or more transitions to spatially and/or spin-ordered phases as the density is decreased, ultimately forming a Wigner crystal in the dilute, strongly-interacting limit. Interesting, unexpected behavior is observed with decreasing electron density as the electrons' interactions become increasingly important relative to their kinetic energy: the resistivity undergoes a transition from metallic to insulating temperature dependence; the resistance increases sharply and then saturates abruptly with increasing in-plane magnetic field; a number of experiments indicate that the electrons' effective mass exhibits a substantial increase approaching a finite ``critical'' density. There has been a great deal of debate concerning the underlying physics in these systems, and many have questioned whether the change of the resistivity from metallic to insulating signals a phase transition or a crossover. In this talk, I will report measurements that show that with decreasing density ns, the thermopower S of a low-disorder 2D electron system in silicon exhibits a sharp increase by more than an order of magnitude, tending to a divergence at a finite, disorder-independent density nt, consistent with the critical form (- T / S) ~(ns -nt) x with x = 1 . 0 +/- 0 . 1 (T is the temperature). Unlike the resistivity which may not clearly distinguish between a transition and crossover behavior, the thermopower provides clear evidence that a true phase transition occurs with decreasing density to a new low-density phase. Work supported by DOE Grant DE-FG02-84ER45153, BSF grant 2006375, RFBR, RAS, and the Russian Ministry of Science.
Direct Visualization of Valence Electron Motion Using Strong-Field Photoelectron Holography
He, Mingrui; Li, Yang; Zhou, Yueming; Li, Min; Cao, Wei; Lu, Peixiang
2018-03-01
Watching the valence electron move in molecules on its intrinsic timescale has been one of the central goals of attosecond science and it requires measurements with subatomic spatial and attosecond temporal resolutions. The time-resolved photoelectron holography in strong-field tunneling ionization holds the promise to access this realm. However, it remains to be a challenging task hitherto. Here we reveal how the information of valence electron motion is encoded in the hologram of the photoelectron momentum distribution (PEMD) and develop a novel approach of retrieval. As a demonstration, applying it to the PEMDs obtained by solving the time-dependent Schrödinger equation for the prototypical molecule H2+ , the attosecond charge migration is directly visualized with picometer spatial and attosecond temporal resolutions. Our method represents a general approach for monitoring attosecond charge migration in more complex polyatomic and biological molecules, which is one of the central tasks in the newly emerging attosecond chemistry.
Charging dynamics and strong localization of a two-dimensional electron cloud
International Nuclear Information System (INIS)
Dianoux, R; Smilde, H J H; Marchi, F; Buffet, N; Mur, P; Comin, F; Chevrier, J
2007-01-01
The dynamics of charge injection in silicon nanocrystals embedded in a silicon dioxide matrix is studied using electrostatic force microscopy. We show that the presence of silicon nanocrystals with a density of 10 11 cm -2 is essential for strong localization of charges, and results in exceptional charge retention properties compared to nanocrystal-free SiO 2 samples. In both systems, a logarithmic dependence of the diameter of the charged area on the injection time is experimentally observed on a timescale between 0.1 and 10 s (voltage≤10 V). A field-emission injection, limited by Coulomb blockade and a lateral charge spreading due to a repulsive radial electric field are used to model the sample charging. Once the tip is retracted, the electron cloud is strongly confined in the nanocrystals and remains static
International Nuclear Information System (INIS)
Dorado, B.
2010-09-01
Uranium dioxide UO 2 is the standard nuclear fuel used in pressurized water reactors. During in-reactor operation, the fission of uranium atoms yields a wide variety of fission products (FP) which create numerous point defects while slowing down in the material. Point defects and FP govern in turn the evolution of the fuel physical properties under irradiation. In this study, we use electronic structure calculations in order to better understand the fuel behavior under irradiation. In particular, we investigate point defect behavior, as well as the stability of three volatile FP: iodine, krypton and xenon. In order to take into account the strong correlations of uranium 5f electrons in UO 2 , we use the DFT+U approximation, based on the density functional theory. This approximation, however, creates numerous metastable states which trap the system and induce discrepancies in the results reported in the literature. To solve this issue and to ensure the ground state is systematically approached as much as possible, we use a method based on electronic occupancy control of the correlated orbitals. We show that the DFT+U approximation, when used with electronic occupancy control, can describe accurately point defect and fission product behavior in UO 2 and provide quantitative information regarding point defect transport properties in the oxide fuel. (author)
Davis, J. C. Séamus; Lee, Dung-Hai
2013-01-01
Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron–electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron–electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron–electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs. PMID:24114268
Energy Technology Data Exchange (ETDEWEB)
Rose, Harvey [Los Alamos National Laboratory; Daughton, W [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory
2009-01-01
The onset of Stimulated Raman scatter from an intense laser speckle is the simplest experimentally realizable laser-plasma-interaction environment. Despite this data and recent 3D particle simulations, the controlling mechanism at the onset of backscatter in the kinetic regime when strong electron trapping in the daughter Langmuir wave is a dominant nonlinearity is not understood. This paper explores the consequences of assuming that onset is controlled by large thermal fluctuations. A super exponential dependence of mean reflectivity on speckle intensity in the onset regime is predicted.
Peculiarities of two-electron atom ionization in strong electromagnetic field
International Nuclear Information System (INIS)
Ovodova, O.V.; Popov, A.M.; Tikhonova, O.V.
1997-01-01
One-dimensional model of helium atom in strong field of electromagnetic wave of femtosecond activity is plotted within the Hartree method frames. Comparison of 'exact' calculations with the calculations conducted within the frames of the 'frozen' and 'passive' electrons is made. The nonmonotonous dependence of one-dimensional ionization probability on the radiation intensity is found. It is shown that the ionization minima are connected with multiphoton resonances between various atomic states, originating due to the Stark effect. It is supposed that the effect of ionization suppression in this case is related to interference stabilization
Samkharadze, N; Kumar, A; Manfra, M J; Pfeiffer, L N; West, K W; Csáthy, G A
2011-05-01
We fabricated a He-3 immersion cell for transport measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's environment in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional electron gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK.
Astrelin, V. T.; Arzhannikov, A. V.; Burdakov, A. V.; Sinitskii, S. L.; Stepanov, V. D.
2009-05-01
The geometry of the ribbon diode of the U-2 accelerator is optimized to increase both the current density and the total current of the relativistic electron beam for its subsequent injection into the plasma of a multimirror GOL-3 trap. Beam simulation in the diode was performed using the POISSON-2 applied software modified on the basis of the results obtained using the theory of a planar diode in an inclined magnetic field. As a result of the optimization, the diode geometry and the magnetic field configuration were found that should provide a factor of 1.5-2 increase in the current density in experiments with a small angular divergence of electron velocities.
Control and dynamics of attosecond electron wave packets in strong laser fields
International Nuclear Information System (INIS)
Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier; Lopez-Martens, R.; Valentin, C.; Balcou, P.; Kazamias, S.; Mauritsson, J.; Gaarde, M.B.; Schafer, K.J.; Mairess, Y.; Wabnitz, H.; Boutu, W.; Salieres, P.
2005-01-01
Full text: Trains of attosecond pulses, emerging from the phase-locking of high-order harmonics generated in a strong laser field are now being routinely produced and characterized in a few laser laboratories. Attosecond pulse trains (APTs) are flexible attosecond sources, since the amplitude and relative phase of the spectral components (the harmonics) can be tailored, allowing us to vary both the duration and the carrier frequency of the pulses. Attosecond pulses interacting with a gas of atoms generate electron wave packets (EWPs), which are temporally localized with approximately the same duration as the attosecond pulses. In contrast to the tunneling electron wave packets giving rise to processes such as high-order harmonic generation and above-threshold-ionization (ATI), the properties of these EWPs are inherited from the attosecond pulses through the single-photon ionization step. Thus the energy and temporal characteristics of the EWPs can be varied independently of the process under investigation, by controlling the properties of the attosecond pulses. This talk will describe two recent experiments done in Lund. First we report on the generation, compression and delivery on target of ultrashort extreme-ultraviolet light pulses using external amplitude and phase control. The APT is synthesized from the 13 th to 35 th harmonics of a 35 fs Ti:sapphire laser. The harmonics are generated by focusing the laser beam into a window-less gas cell, filled with argon. To achieve the required on-target attosecond pulses, the harmonics are filtered spatially, using a fixed aperture, and spectrally using aluminum filters. The aluminum filters also serve the purpose of compressing the attosecond pulses, using the negative group-delay dispersion of aluminum to compensate for the intrinsic positive chirp of the attosecond pulses. This experiment demonstrates a practical method for the synthesis and control of attosecond waveforms, and in this case the production of pulses