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Sample records for equilibrium electron beam

  1. Theories of statistical equilibrium in electron-positron colliding-beam storage rings

    SciTech Connect

    Schonfeld, J.F.

    1985-01-01

    In this lecture I introduce you to some recent theoretical work that represents a significant and long overdue departure from the mainstream of ideas on the physics of colliding- beam storage rings. The goal of the work in question is to understand analytically - without recourse to computer simulation - the role that dissipation and noise play in the observed colliding-beam behavior of electron-positron storage rings.

  2. Equilibrium Beam Invariants of an Electron Storage Ring with Linear x-y Coupling

    SciTech Connect

    Wu, Juhao; Nash, B.E.; Chao, A.W.; /SLAC

    2005-09-14

    In accelerators, it is common that the motion of the horizontal x-plane is coupled to that of the vertical y-plane. Such coupling will induce tune shifts and can cause instabilities. The damping and diffusion rates are also affected, which in turn will lead to a change in the equilibrium invariants. With the perturbative approach which is also used for synchrobetatron coupling [B. Nash, J.Wu, and A. Chao, work in progress], we study the x-y coupled case in this paper. Starting from the one-turn map, we give explicit formulae for the tune shifts, damping and diffusion rates, and the equilibrium invariants. We focus on the cases where the system is near the integer or half integer, and sum or difference resonances where small coupling can cause a large change in the beam distribution.

  3. Chemical kinetics and relaxation of non-equilibrium air plasma generated by energetic photon and electron beams

    NASA Astrophysics Data System (ADS)

    Maulois, Melissa; Ribière, Maxime; Eichwald, Olivier; Yousfi, Mohammed; Azaïs, Bruno

    2016-04-01

    The comprehension of electromagnetic perturbations of electronic devices, due to air plasma-induced electromagnetic field, requires a thorough study on air plasma. In the aim to understand the phenomena at the origin of the formation of non-equilibrium air plasma, we simulate, using a volume average chemical kinetics model (0D model), the time evolution of a non-equilibrium air plasma generated by an energetic X-ray flash. The simulation is undertaken in synthetic air (80% N2 and 20% O2) at ambient temperature and atmospheric pressure. When the X-ray flash crosses the gas, non-relativistic Compton electrons (low energy) and a relativistic Compton electron beam (high energy) are simultaneously generated and interact with the gas. The considered chemical kinetics scheme involves 26 influent species (electrons, positive ions, negative ions, and neutral atoms and molecules in their ground or metastable excited states) reacting following 164 selected reactions. The kinetics model describing the plasma chemistry was coupled to the conservation equation of the electron mean energy, in order to calculate at each time step of the non-equilibrium plasma evolution, the coefficients of reactions involving electrons while the energy of the heavy species (positive and negative ions and neutral atoms and molecules) is assumed remaining close to ambient temperature. It has been shown that it is the relativistic Compton electron beam directly created by the X-ray flash which is mainly responsible for the non-equilibrium plasma formation. Indeed, the low energy electrons (i.e., the non-relativistic ones) directly ejected from molecules by Compton collisions contribute to less than 1% on the creation of electrons in the plasma. In our simulation conditions, a non-equilibrium plasma with a low electron mean energy close to 1 eV and a concentration of charged species close to 1013 cm-3 is formed a few nanoseconds after the peak of X-ray flash intensity. 200 ns after the flash

  4. Relativistic electron beam generator

    DOEpatents

    Mooney, L.J.; Hyatt, H.M.

    1975-11-11

    A relativistic electron beam generator for laser media excitation is described. The device employs a diode type relativistic electron beam source having a cathode shape which provides a rectangular output beam with uniform current density.

  5. Electron beam focusing system

    SciTech Connect

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  6. Electron Beam Freeform Fabrication

    NASA Video Gallery

    Electron Beam Freeform Fabrication (EBF3) is a process by which NASA hopes to build metal parts in zero gravity environments. It's a layer-additive process that uses an electron beam and a solid wi...

  7. Electron beam device

    DOEpatents

    Beckner, E.H.; Clauser, M.J.

    1975-08-12

    This patent pertains to an electron beam device in which a hollow target is symmetrically irradiated by a high energy, pulsed electron beam about its periphery and wherein the outer portion of the target has a thickness slightly greater than required to absorb the electron beam pulse energy. (auth)

  8. Rippled beam free electron Laser Amplifier

    SciTech Connect

    Carlsten, Bruce E.

    1998-04-21

    A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a T{sub 0n} mode. A waveguide defines an axial centerline and . A solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

  9. Rippled beam free electron laser amplifier

    DOEpatents

    Carlsten, Bruce E.

    1999-01-01

    A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

  10. Dynamics of Charged Particles in an Adiabatic Thermal Beam Equilibrium

    NASA Astrophysics Data System (ADS)

    Chen, Chiping; Wei, Haofei

    2010-11-01

    Charged-particle motion is studied in the self-electric and self-magnetic fields of a well-matched, intense charged-particle beam and an applied periodic solenoidal magnetic focusing field. The beam is assumed to be in a state of adiabatic thermal equilibrium. The phase space is analyzed and compared with that of the well-known Kapchinskij-Vladimirskij (KV)-type beam equilibrium. It is found that the widths of nonlinear resonances in the adiabatic thermal beam equilibrium are narrower than those in the KV-type beam equilibrium. Numerical evidence is presented, indicating almost complete elimination of chaotic particle motion in the adiabatic thermal beam equilibrium.

  11. (Pulsed electron beam precharger)

    SciTech Connect

    Finney, W.C.; Shelton, W.N.

    1990-01-01

    This report discusses the following topics on electron beam guns: Precharger Modification; Installation of Charge vs. Radius Apparatus; High Concentration Aerosol Generation; and Data Acquisition and Analysis System.

  12. Electron beam polarimetry

    SciTech Connect

    Sinclair, C.K.

    1998-12-01

    Along with its well known charge and mass, the electron also carries an intrinsic angular momentum, or {ital spin}. The rules of quantum mechanics allow us to measure only the probability that the electron spin is in one of two allowed spin states. When a beam carries a net excess of electrons in one of these two allowed spin states, the beam is said to be {ital polarized}. The beam polarization may be measured by observing a sufficient number of electrons scattered by a spin-dependent interaction. For electrons, the useful scattering processes involve Coulomb scattering by heavy nuclei, or scattering from either polarized photons or other polarized electrons (known as Mott, Compton, and Mo/ller scattering, respectively). In this tutorial, we will briefly review how beam polarization is measured through a general scattering process, followed by a discussion of how the three scattering processes above are used to measure electron beam polarization. Descriptions of electron polarimeters based on the three scattering processes will be given. {copyright} {ital 1998 American Institute of Physics.}

  13. Electron beam polarimetry

    NASA Astrophysics Data System (ADS)

    Sinclair, Charles K.

    1998-12-01

    Along with its well known charge and mass, the electron also carries an intrinsic angular momentum, or spin. The rules of quantum mechanics allow us to measure only the probability that the electron spin is in one of two allowed spin states. When a beam carries a net excess of electrons in one of these two allowed spin states, the beam is said to be polarized. The beam polarization may be measured by observing a sufficient number of electrons scattered by a spin-dependent interaction. For electrons, the useful scattering processes involve Coulomb scattering by heavy nuclei, or scattering from either polarized photons or other polarized electrons (known as Mott, Compton, and Mo/ller scattering, respectively). In this tutorial, we will briefly review how beam polarization is measured through a general scattering process, followed by a discussion of how the three scattering processes above are used to measure electron beam polarization. Descriptions of electron polarimeters based on the three scattering processes will be given.

  14. Electron beam dose calculations.

    PubMed

    Hogstrom, K R; Mills, M D; Almond, P R

    1981-05-01

    Electron beam dose distributions in the presence of inhomogeneous tissue are calculated by an algorithm that sums the dose distribution of individual pencil beams. The off-axis dependence of the pencil beam dose distribution is described by the Fermi-Eyges theory of thick-target multiple Coulomb scattering. Measured square-field depth-dose data serve as input for the calculations. Air gap corrections are incorporated and use data from'in-air' measurements in the penumbra of the beam. The effective depth, used to evaluate depth-dose, and the sigma of the off-axis Gaussian spread against depth are calculated by recursion relations from a CT data matrix for the material underlying individual pencil beams. The correlation of CT number with relative linear stopping power and relative linear scattering power for various tissues is shown. The results of calculations are verified by comparison with measurements in a 17 MeV electron beam from the Therac 20 linear accelerator. Calculated isodose lines agree nominally to within 2 mm of measurements in a water phantom. Similar agreement is observed in cork slabs simulating lung. Calculations beneath a bone substitute illustrate a weakness in the calculation. Finally a case of carcinoma in the maxillary antrum is studied. The theory suggests an alternative method for the calculation of depth-dose of rectangular fields.

  15. Electron beam generation in Tevatron electron lenses

    SciTech Connect

    Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.; /Novosibirsk, IYF

    2006-08-01

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices.

  16. Measuring electron beam polarization

    NASA Astrophysics Data System (ADS)

    Napolitano, J.

    1992-12-01

    A two-hour discussion session was held on electron beam polarimetry including representatives from Halls A, B, and C. Presentations included a description of an existing Mo/ller polarimeter at the MIT-Bates laboratory, plans for Mo/ller polarimeters in Halls A and B, and a Compton (i.e., ``laser backscatter'') polarimeter planned for Hall A. This paper is a summary of those discussions.

  17. Compact electron beam focusing column

    SciTech Connect

    Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

    2001-07-13

    A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

  18. Depressed collector for electron beams

    NASA Technical Reports Server (NTRS)

    Ives, R. Lawrence (Inventor)

    2005-01-01

    A depressed collector for recovery of spent beam energy from electromagnetic sources emitting sheet or large aspect ration annular electron beams operating aver a broad range of beam voltages and currents. The collector incorporates a trap for capturing and preventing the return of reflected and secondary electrons.

  19. Pulsed electron beam precharger

    SciTech Connect

    Finney, W.C.; Shelton, W.N.

    1990-01-01

    Florida State University is investigating the concept of pulsed electron beams for fly ash precipitation. This report describes the results and data on three of the subtasks of this project and preliminary work only on the remaining five subtasks. Described are the modification of precharger for pulsed and DC energization of anode; installation of the Q/A measurement system; and modification and installation of pulsed power supply to provide both pulsed and DC energization of the anode. The other tasks include: measurement of the removal efficiency for monodisperse simulated fly ash particles; measurement of particle charge; optimization of pulse energization schedule for maximum removal efficiency; practical assessment of results; and measurement of the removal efficiency for polydisperse test particles. 15 figs., 1 tab. (CK)

  20. Pulsed electron beam precharger

    SciTech Connect

    Finney, W.C.; Shelton, W.N.

    1990-01-01

    In this report, a short review of electron beam particle precharging using a pulsed electric field is presented in Section B-1. Section B-2 details the design and installation of a remote focusing gear train which will allow much greater control over the particle charge measurement capability of the charge vs. radius apparatus. Under Section B-3, progress on the electrical shielding of the rotating spark gap power supply using a large Faraday cage is described. Efforts to prevent RFI interference from adversely affecting the Climet particle counter and the MicroMac current measurement device using a variety of techniques are also presented in this section. The basic effort is to optimize the removal efficiency for fly ash particles. 13 figs.

  1. Electron Beam Diagnostics in Plasmas Based on Electron Beam Ionization

    NASA Astrophysics Data System (ADS)

    Leonhardt, Darrin; Leal-Quiros, Edbertho; Blackwell, David; Walton, Scott; Murphy, Donald; Fernsler, Richard; Meger, Robert

    2001-10-01

    Over the last few years, electron beam ionization has been shown to be a viable generator of high density plasmas with numerous applications in materials modification. To better understand these plasmas, we have fielded electron beam diagnostics to more clearly understand the propagation of the beam as it travels through the background gas and creates the plasma. These diagnostics vary greatly in sophistication, ranging from differentially pumped systems with energy selective elements to metal 'hockey pucks' covered with thin layers of insulation to electrically isolate the detector from the plasma but pass high energy beam electrons. Most importantly, absolute measurements of spatially resolved beam current densities are measured in a variety of pulsed and continuous beam sources. The energy distribution of the beam current(s) will be further discussed, through experiments incorporating various energy resolving elements such as simple grids and more sophisticated cylindrical lens geometries. The results are compared with other experiments of high energy electron beams through gases and appropriate disparities and caveats will be discussed. Finally, plasma parameters are correlated to the measured beam parameters for a more global picture of electron beam produced plasmas.

  2. Instability versus equilibrium propagation of a laser beam in plasma.

    PubMed

    Lushnikov, Pavel M; Rose, Harvey A

    2004-06-25

    We obtain, for the first time, an analytic theory of the forward stimulated Brillouin scattering instability of a spatially and temporally incoherent laser beam that controls the transition between statistical equilibrium and nonequilibrium (unstable) self-focusing regimes of beam propagation. The stability boundary may be used as a comprehensive guide for inertial confinement fusion designs. Well into the stable regime, an analytic expression for the angular diffusion coefficient is obtained, which provides an essential correction to a geometric optic approximation for beam propagation.

  3. Generation of electron Airy beams.

    PubMed

    Voloch-Bloch, Noa; Lereah, Yossi; Lilach, Yigal; Gover, Avraham; Arie, Ady

    2013-02-21

    Within the framework of quantum mechanics, a unique particle wave packet exists in the form of the Airy function. Its counterintuitive properties are revealed as it propagates in time or space: the quantum probability wave packet preserves its shape despite dispersion or diffraction and propagates along a parabolic caustic trajectory, even though no force is applied. This does not contradict Newton's laws of motion, because the wave packet centroid propagates along a straight line. Nearly 30 years later, this wave packet, known as an accelerating Airy beam, was realized in the optical domain; later it was generalized to an orthogonal and complete family of beams that propagate along parabolic trajectories, as well as to beams that propagate along arbitrary convex trajectories. Here we report the experimental generation and observation of the Airy beams of free electrons. These electron Airy beams were generated by diffraction of electrons through a nanoscale hologram, which imprinted on the electrons' wavefunction a cubic phase modulation in the transverse plane. The highest-intensity lobes of the generated beams indeed followed parabolic trajectories. We directly observed a non-spreading electron wavefunction that self-heals, restoring its original shape after passing an obstacle. This holographic generation of electron Airy beams opens up new avenues for steering electronic wave packets like their photonic counterparts, because the wave packets can be imprinted with arbitrary shapes or trajectories.

  4. Determination of the secondary electron equilibrium using an extrapolation chamber

    SciTech Connect

    Marshall, E.T.; Vaziri, K.; Krueger, F.P.; Cossairt, J.D.

    1996-09-01

    To ensure that the external personnel dosimetry program conducted by U. S. Department of Energy (DOE) contractors is of the highest quality, the DOE established the Department of Energy Laboratory Accreditation Program or DOELAP. The contractor`s dosimetry program is assessed against the criteria set forth for dosimeter performance and the associated quality assurance and calibration programs. Although personnel dosimeters are not processed or calibrated by Fermilab, a proactive quality assurance program is in place to ensure accurate monitoring. This program includes quarterly blind testing of the dosimeters used by personnel. During the on-site assessment conducted of Fermilab`s external dosimetry program during May 1994, an observation with regard to equipment maintenance and calibration was made: ``calibration personnel should probably review the electron secondary equilibrium needs at various irradiation distances from the {sup 137}Cs irradiation systems`` The majority of the secondary electrons are generated through interactions of the beam with the collimator. Secondary electrons increase the low energy component of the radiation field, increasing the shallow doses measured. For dosimetric purposes, this increase needs to be defined so appropriate corrections to calculations or modifications to the facility can be made. Prompted by this observation, a study was designed to investigate the electron secondary equilibrium in the facility used for the blind testing by determining the dose equivalent as a function of depth in a tissue-equivalent medium. This presentation summarizes the methodology utilized and results of the investigation.

  5. Repetitively pumped electron beam device

    DOEpatents

    Schlitt, L.G.

    1979-07-24

    Disclosed is an apparatus for producing fast, repetitive pulses of controllable length of an electron beam by phased energy storage in a transmission line of length matched to the number of pulses and specific pulse lengths desired. 12 figs.

  6. Dual-Cathode Electron-Beam Source

    NASA Technical Reports Server (NTRS)

    Bradley, James G.; Conley, Joseph M.; Wittry, David B.

    1988-01-01

    Beam from either cathode electromagnetically aligned with exit port. Electron beam from either of two cathodes deflected by magnetic and electric fields to central axis. Mechanical alignment of beam easy because cathode axes, anode apertures, and electron trajectories coplanar. Applications where uninterrupted service needed: scanning electron microscopes, transmission electron microscopes, electron-beam lithography equipment, Auger instruments, and microfocused x-ray sources.

  7. Electron beam pumped semiconductor laser

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  8. Relativistic Electron Beams Above Thunderclouds

    NASA Astrophysics Data System (ADS)

    Fullekrug, Martin; Roussel-Dupre, Robert; Symbalisty, Eugene; Chanrion, Olivier; van der Velde, Oscar; Soula, Serge; Odzimek, Anna; Bennett, Alec; Whitley, Toby; Neubert, Torsten

    2010-05-01

    It has recently been discovered that lightning discharges generate upward-directed relativistic electron beams above thunderclouds. This extends the phenomenon of relativistic runaway breakdown believed to occur inside thunderclouds to the atmosphere above thunderclouds. This marks a profound advance in our understanding of the atmosphere because we now know it acts as a giant, natural, particle accelerator. The accelerated electrons can reach significant relativistic energies of some MeV during their passage from the troposphere, through the middle atmosphere, into near-Earth space. These relativistic electron beams constitute a current above thunderclouds and effectively transfer energy from the troposphere to the middle atmosphere. This coupling process thereby forms a novel element of the global atmospheric electric circuit which links tropospheric thunderclouds to the atmosphere above. This contribution describes the radio remote sensing of upward electron beams to determine their occurrence frequency and to characterise their physical properites.

  9. Polarized electron beams at SLAC

    SciTech Connect

    Moffeit, K.C.

    1992-11-01

    SLAC has successfully accelerated high energy polarized electrons for the Stanford Linear Collider and fixed polarized nuclear target experiments. The polarized electron beams at SLAC use a gallium arsenide (GaAlAs for E-142) photon emission source to provide the beam of polarized electrons with polarization of approximately 28% (41% for E-142). While the beam emittance is reduced in the damping ring for SLC operation a system of bend magnets and superconducting solenoids preserve and orient the spin direction for maximum longitudinal polarization at the collision point. The electron polarization is monitored with a Compton scattering polarimeter, and was typically 22% at the e[plus]e[minus] collision point for the 1992 run. Improvements are discussed to increase the source polarization and to reduce the depolarization effects between the source and the collision point.

  10. Polarized electron beams at SLAC

    SciTech Connect

    Moffeit, K.C.

    1992-11-01

    SLAC has successfully accelerated high energy polarized electrons for the Stanford Linear Collider and fixed polarized nuclear target experiments. The polarized electron beams at SLAC use a gallium arsenide (GaAlAs for E-142) photon emission source to provide the beam of polarized electrons with polarization of approximately 28% (41% for E-142). While the beam emittance is reduced in the damping ring for SLC operation a system of bend magnets and superconducting solenoids preserve and orient the spin direction for maximum longitudinal polarization at the collision point. The electron polarization is monitored with a Compton scattering polarimeter, and was typically 22% at the e{plus}e{minus} collision point for the 1992 run. Improvements are discussed to increase the source polarization and to reduce the depolarization effects between the source and the collision point.

  11. Electron Beam Materials Irradiators

    NASA Astrophysics Data System (ADS)

    Cleland, Marshall R.

    2012-06-01

    Radiation processing is a well established method for enhancing the properties of materials and commercial products by treating them with ionizing energy in the form of high-energy electrons, X-rays, and gamma rays. Beneficial effects include polymerizing, cross-linking, grafting and degrading plastics, sterilizing single-use medical devices, disinfecting and disinfesting fresh foods, purifying drinking water, treating wastewater and other toxic waste materials that harm the environment, and many other applications that are still being evaluated. Industrial electron accelerators of several types have been developed and are being used for these applications. More than 1800 electron accelerators are presently installed in facilities worldwide for these purposes.

  12. Electron beam ion source and electron beam ion trap (invited).

    PubMed

    Becker, Reinard; Kester, Oliver

    2010-02-01

    The electron beam ion source (EBIS) and its trap variant [electron beam ion trap (EBIT)] celebrated their 40th and 20th anniversary, respectively, at the EBIS/T Symposium 2007 in Heidelberg. These technologically challenging sources of highly charged ions have seen a broad development in many countries over the last decades. In contrast to most other ion sources the recipe of improvement was not "sorcery" but a clear understanding of the physical laws and obeying the technological constraints. This review will report important achievements of the past as well as promising developments in the future.

  13. Beam Studies with Electron Columns

    SciTech Connect

    Shiltsev, V.; Valishev, A.; Kuznetsov, G.; Kamerdzhiev, V.; Romanov, A.; /Novosibirsk, IYF

    2009-04-01

    We report preliminary results of experimental studies of 'electron columns' in the Tevatron and in a specialized test setup. In the Tevatron, a beam of 150 GeV protons ionizes residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are observed. In the test setup, we observe effects pointing to accumulation and escape of ionization electrons.

  14. Intense electron beam propagation across a magnetic field

    SciTech Connect

    Zhang, X.; Striffler, C.D.; Yao, R.L.; Destler, W.W.; Reiser, M.P.

    1989-01-01

    In this paper we consider the propagation of an intense electron-ion beam across an applied magnetic field. In the absence of the applied field, the beam system is in a Bennett equilibrium state that involves electrons with both large axial and thermal velocities and a cold stationary space-charge neutralizing ion species. Typical parameters under consideration are V{sub o} {approximately} 1 MV, I {approximately} 5 kA, T{sub e} {approximately} 100 keV, and beam radii {approximately} 1 cm. We find that in the intense beam regime, the propagation is limited due to space-charge depression caused by the deflection of the electron beam by the transverse field. This critical field is of the order of the peak self-magnetic field of the electron beam which is substantially higher than the single particle cut-off field. 8 refs., 3 figs.

  15. Low electron beam energy CIVA analysis of passivated ICs

    SciTech Connect

    Cole, E.I. Jr.; Soden, J.M.; Dodd, B.A.; Henderson, C.L.

    1994-08-01

    Low Energy Charge-Induced Voltage Alteration (LECIVA) is a new scanning electron microscopy technique developed to localize open conductors in passivated ICs. LECIVA takes advantage of recent experimental work showing that the dielectric surface equilibrium voltage has an electron flux density dependence at low electron beam energies ({le}1.0 keV). The equilibrium voltage changes from positive to negative as the electron flux density is increased. Like Charge-Induced Voltage Alteration (CIVA), LECIVA images are produced from the voltage fluctuations of a constant current power supply as an electron beam is scanned over the IC surface. LECIVA image contrast is generated only by the electrically open part of a conductor, yielding, the same high selectivity demonstrated by CIVA. Because LECIVA is performed at low beam energies, radiation damage by the primary electrons and x-rays to MOS structures is far less than that caused by CIVA. LECIVA may also be performed on commercial electron beam test systems that do not have high primary electron beam energy capabilities. The physics of LECIVA signal generation are described. LECIVA imaging examples illustrate its utility on both a standard scanning electron microscope (SEM) and a commercial electron beam test system.

  16. Cylindrical electron beam diode

    DOEpatents

    Bolduc, Paul E.

    1976-01-01

    A diode discharge device may include a tubular anode concentrically encircled by and spaced from a tubular cathode electrode with ends intermediate the ends of said anode electrode, and a metal conductive housing having a tubular wall disposed around the cathode electrode with end walls connected to the anode electrode. High energy electron current coupling is through an opening in the housing tubular wall to a portion of the cathode electrode intermediate its ends. Suitable utilization means may be within the anode electrode at positions to be irradiated by electrons emitted from the cathode electrode and transmitted through the anode walls.

  17. Electron beam cutting

    DOEpatents

    Mochel, Margaret E.; Humphreys, Colin J.

    1985-04-02

    A method for the cutting of holes 20 Angstroms in diameter, or lines 20 Angstroms wide in a material having positive ionic conduction by the use of a focused electron probe is described. The holes and lines are stable under ambient conditions.

  18. Electron beam cutting

    DOEpatents

    Mochel, M.E.; Humphreys, C.J.

    1985-04-02

    A method for the cutting of holes 20 Angstroms in diameter, or lines 20 Angstroms wide in a material having positive ionic conduction by the use of a focused electron probe is described. The holes and lines are stable under ambient conditions. 2 figs.

  19. Shimmed electron beam welding process

    DOEpatents

    Feng, Ganjiang; Nowak, Daniel Anthony; Murphy, John Thomas

    2002-01-01

    A modified electron beam welding process effects welding of joints between superalloy materials by inserting a weldable shim in the joint and heating the superalloy materials with an electron beam. The process insures a full penetration of joints with a consistent percentage of filler material and thereby improves fatigue life of the joint by three to four times as compared with the prior art. The process also allows variable shim thickness and joint fit-up gaps to provide increased flexibility for manufacturing when joining complex airfoil structures and the like.

  20. Neutral beam spectroscopy for equilibrium and stability measurements for the PEGASUS toroidal experiment (abstract)

    SciTech Connect

    Thorson, T.; Fonck, R.; Lewicki, B.

    1999-01-01

    An optical neutral beam spectroscopy system is being designed to provide equilibrium and stability measurements for the PEGASUS toroidal experiment. Spatially localized measurements of the electron temperature and plasma density are possible by observing the intensity of the collisionally induced neutral beam fluorescence. In a helium beam, the population of the singlet levels are relatively independent of the plasma temperature compared to the triplet levels. Therefore, the ratio of intensities of a triplet transition (e.g., 3{sup 3}S{r_arrow}2{sup 3}P, {lambda}=706.5 nm) to a singlet transition (e.g., 3{sup 1}P{r_arrow}2{sup 1}S, {lambda}=501.6 nm) provides a measure of the local plasma temperature for the range 10 eV{lt}T{sub e}{lt}1.0 keV. The plasma density profile can be inferred from the attenuation of the beam fluorescence signal as the beam passes through the plasma. Additionally in a deuterium beam, the local plasma density can be directly inferred from the local radial gradient in the observed beam fluorescence signal. Plasma stability will be studied with localized magnetohydrodynamics measurements via beam emission spectroscopy, which otherwise is problematic for low-field spherical plasmas. {copyright} {ital 1999 American Institute of Physics.}

  1. Light modulated electron beam driven radiofrequency emitter

    DOEpatents

    Wilson, M.T.; Tallerico, P.J.

    1979-10-10

    The disclosure relates to a light modulated electron beam-driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  2. Electron Beam Could Probe Recombination Centers

    NASA Technical Reports Server (NTRS)

    Vonroos, O.

    1983-01-01

    Electron beam probe technique estimate electron/hole capture cross sections in semiconductors with wide band gaps. Amplitude-modulated electron beam induces short-circuit current collected by ohmic contacts. Phase shift between this current and electron-beam current measured as function of frequency. Results of measurements used to ascertain recombination rates and energy levels.

  3. Static analysis of possible emittance growth of intense charged particle beams with thermal equilibrium distribution

    SciTech Connect

    Kikuchi, Takashi; Horioka, Kazuhiko

    2009-05-15

    Possible emittance growths of intense, nonuniform beams during a transport in a focusing channel are derived as a function of nonlinear field energy and space charge tune depression factors. The nonlinear field energy of the beam with thermal equilibrium distribution is estimated by considering the particle distribution across the cross section of the beam. The results show that the possible emittance growth can be suppressed by keeping the beam particle in thermal equilibrium distribution during the beam transport.

  4. Storage-ring Electron Cooler for Relativistic Ion Beams

    SciTech Connect

    Lin, Fanglei; Derbenev, Yaroslav; Douglas, David R.; Guo, Jiquan; Johnson, Rolland P.; Krafft, Geoffrey A.; Morozov, Vasiliy; Zhang, Yuhong

    2016-05-01

    Application of electron cooling at ion energies above a few GeV has been limited due to reduction of electron cooling efficiency with energy and difficulty in producing and accelerating a high-current high-quality electron beam. A high-current storage-ring electron cooler offers a solution to both of these problems by maintaining high cooling beam quality through naturally-occurring synchrotron radiation damping of the electron beam. However, the range of ion energies where storage-ring electron cooling can be used has been limited by low electron beam damping rates at low ion energies and high equilibrium electron energy spread at high ion energies. This paper reports a development of a storage ring based cooler consisting of two sections with significantly different energies: the cooling and damping sections. The electron energy and other parameters in the cooling section are adjusted for optimum cooling of a stored ion beam. The beam parameters in the damping section are adjusted for optimum damping of the electron beam. The necessary energy difference is provided by an energy recovering SRF structure. A prototype linear optics of such storage-ring cooler is presented.

  5. Electron Beam IEMP Simulation Development

    DTIC Science & Technology

    1975-08-01

    Effect of Injected Current Pulse Width Variation Upon Transmittfed Current Pulse 69 4.10 Open Shutter Photograph of Surface Flashover on Dielectric Tube...occurred, presumably by electrical breakdown In volume. However it was no+ observed In all cases. Surface flashover Is another electrical failure mode...early in the Injected pulse 71 TDIELECTRIC TUBE ELECTRON BEAM oil~ Flgu--e 4.10 Open Shutter Photograph of Surface Flashover on Dielectric Tube 7

  6. Practical Teaching about Electron Beams

    ERIC Educational Resources Information Center

    Strawson, R. J.

    2009-01-01

    If you have seen tubes like the ones we describe here in the back of a cupboard but have been reluctant to use them, now is the time to get them out. The aim of this article is to record the history of teaching about electron beams, particularly with Teltron equipment, and in doing so encourage those schools that are equipped with these tubes to…

  7. Laser wakefield acceleration of polarized electron beams

    NASA Astrophysics Data System (ADS)

    Pugacheva, D. V.; Andreev, N. E.; Cros, B.

    2016-11-01

    The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

  8. Electron beam stimulated spin reorientation

    NASA Astrophysics Data System (ADS)

    Monchesky, T. L.; Unguris, J.; Celotta, R. J.

    2003-05-01

    Using scanning electron microscopy with polarization analysis, we observed the electron beam induced switching of the magnetic state of epitaxial single-crystal Fe(110) films grown on atomically flat cleaved GaAs(110). For low film thickness the magnetization lies along the [-110] in-plane direction, while above a thickness of 19 monolayers, the ground state magnetization configuration switches to the [001] in-plane direction. If Fe films are grown to a thickness greater than the critical thickness of the reorientation, the magnetization is caught in a metastable state, oriented along [-110]. We discovered that we can locally switch the metastable state to the stable [001] direction by irradiating the metastable magnetic state with a suitable electron current density. The reversal proceeds by the nucleation and growth of lancet-shaped domains that move in discrete jumps between pinning sites. Our results show that there is a permanent reduction of the strength of defect sites without a permanent change in the overall anisotropy. We demonstrate how an electron beam can be used to locally control domain structure.

  9. Collimation Studies with Hollow Electron Beams

    SciTech Connect

    Stancari, G.; Annala, G.; Johnson, T.R.; Saewert, G.W.; Shiltsev, V.; Still, D.A.; Valishev, A.; /Fermilab

    2011-08-01

    Recent experimental studies at the Fermilab Tevatron collider have shown that magnetically confined hollow electron beams can act as a new kind of collimator for high-intensity beams in storage rings. In a hollow electron beam collimator, electrons enclose the circulating beam. Their electric charge kicks halo particles transversely. If their distribution is axially symmetric, the beam core is unaffected. This device is complementary to conventional two-stage collimation systems: the electron beam can be placed arbitrarily close to the circulating beam; and particle removal is smooth, so that the device is a diffusion enhancer rather than a hard aperture limitation. The concept was tested in the Tevatron collider using a hollow electron gun installed in one of the existing electron lenses. We describe some of the technical aspects of hollow-beam scraping and the results of recent measurements.

  10. Beam/seam alignment control for electron beam welding

    DOEpatents

    Burkhardt, Jr., James H.; Henry, J. James; Davenport, Clyde M.

    1980-01-01

    This invention relates to a dynamic beam/seam alignment control system for electron beam welds utilizing video apparatus. The system includes automatic control of workpiece illumination, near infrared illumination of the workpiece to limit the range of illumination and camera sensitivity adjustment, curve fitting of seam position data to obtain an accurate measure of beam/seam alignment, and automatic beam detection and calculation of the threshold beam level from the peak beam level of the preceding video line to locate the beam or seam edges.

  11. PURIFICATION OF IRIDIUM BY ELECTRON BEAM MELTING

    SciTech Connect

    Ohriner, Evan Keith

    2008-01-01

    The purification of iridium metal by electron beam melting has been characterized for 48 impurity elements. Chemical analysis was performed by glow discharge mass spectrographic (GDMS) analysis for all elements except carbon, which was analyzed by combustion. The average levels of individual elemental impurities in the starting powder varied from 37 g/g to 0.02 g/g. The impurity elements Li, Na, Mg, P, S, Cl, K, Ca, Mn, Co, Ni, Cu, Zn, As, Pd, Ag, Cd, Sn, Sb, Te, Ba, Ce, Tl, Pb, and Bi were not detectable following the purification. No significant change in concentration of the elements Ti, V, Zr, Nb, Mo, and Re was found. The elements B, C, Al, Si, Cr, Fe, Ru, Rh, and Pt were partially removed by vaporization during electron beam melting. Langmuir's equation for ideal vaporization into a vacuum was used to calculate for each impurity element the expected ratio of impurity content after melting to that before melting. Equilibrium vapor pressures were calculated using Henry's law, with activity coefficients obtained from published data for the elements Fe, Ti, and Pt. Activity coefficients were estimated from enthalpy data for Al, Si, V, Cr, Mn, Co, Ni, Zr, Nb, Mo, and Hf and an ideal solution model was used for the remaining elements. The melt temperature was determined from measured iridium weight loss. Excellent agreement was found between measured and calculated impurity ratios for all impurity elements. The results are consistent with some localized heating of the melt pool due to rastering of the electron beam, with an average vaporization temperature of 3100 K as compared to a temperature of 2965 K calculated for uniform heating of the melt pool. The results are also consistent with ideal mixing in the melt pool.

  12. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-01-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*01 mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  13. Nuclear astrophysics and electron beams

    SciTech Connect

    Schwenk, A.

    2013-11-07

    Electron beams provide important probes and constraints for nuclear astrophysics. This is especially exciting at energies within the regime of chiral effective field theory (EFT), which provides a systematic expansion for nuclear forces and electroweak operators based on quantum chromodynamics. This talk discusses some recent highlights and future directions based on chiral EFT, including nuclear structure and reactions for astrophysics, the neutron skin and constraints for the properties of neutron-rich matter in neutron stars and core-collapse supernovae, and the dark matter response of nuclei.

  14. Adjusting an electron beam for drilling

    NASA Technical Reports Server (NTRS)

    Childress, C. L.

    1980-01-01

    Reticle contains two concentric circles: inner circle insures beam circularity and outer circle is guide to prevent beam from cutting workpiece clamp. Precise measurement of beam and clamp are required with old reticle. New reticle speeds up electron-beam drilling process by eliminating need to rotate eyepiece to make measurements against reticle scale.

  15. Electron beam parallel X-ray generator

    NASA Technical Reports Server (NTRS)

    Payne, P.

    1967-01-01

    Broad X ray source produces a highly collimated beam of low energy X rays - a beam with 2 to 5 arc minutes of divergence at energies between 1 and 6 keV in less than 5 feet. The X ray beam is generated by electron bombardment of a target from a large area electron gun.

  16. Definition of Beam Diameter for Electron Beam Welding

    SciTech Connect

    Burgardt, Paul; Pierce, Stanley W.; Dvornak, Matthew John

    2016-03-11

    It is useful to characterize the dimensions of the electron beam during process development for electron beam welding applications. Analysis of the behavior of electron beam welds is simplest when a single number can be assigned to the beam properties that describes the size of the beam spot; this value we generically call the “beam diameter”. This approach has worked well for most applications and electron beam welding machines with the weld dimensions (width and depth) correlating well with the beam diameter. However, in recent weld development for a refractory alloy, Ta-10W, welded with a low voltage electron beam machine (LVEB), it was found that the weld dimensions (weld penetration and weld width) did not correlate well with the beam diameter and especially with the experimentally determined sharp focus point. These data suggest that the presently used definition of beam diameter may not be optimal for all applications. The possible reasons for this discrepancy and a suggested possible alternative diameter definition is the subject of this paper.

  17. Beam rotation and shear in a large electron beam diode

    SciTech Connect

    Mansfield, C.R.; Oona, H.; Shurter, R.P.

    1990-01-01

    The time averaged electron beam current distribution of one of the electron guns of the Large Aperture Module (LAM) of the Aurora laser was measured as part of a larger set of experiments designed to study the electron beam transport to and energy deposition in the LAM laser chamber. The LAM laser chamber has a 1-m {times} 1-m aperture and is pumped from two sides along a 2-m length. A 10 ga. stainless steel sheet was placed inside the laser chamber and served multiple purposes. First, it was used to convert high energy electrons into X-rays in order to make radiograms of the electron beam. Second, the sheet was used as a Faraday cup to measure the total beam current. Third, individual Faraday cups were mounted on the plate to sample the time history of the electron beam at various positions. Each of the LAM electron gun diodes produces a beam of 750 kV electrons with a total current of about 500 kA which is relatively uniform over the cathode area of 1 m {times} 2 m. An applied magnetic field of about 1300 Gauss is used to prevent pinch of the beam during beam transport.

  18. Transverse Mode Electron Beam Microwave Generator

    NASA Technical Reports Server (NTRS)

    Wharton, Lawrence E.

    1994-01-01

    An electron beam microwave device having an evacuated interaction chamber to which are coupled a resonant cavity which has an opening between the resonant cavity and the evacuated interaction chamber and an electron gun which causes a narrow beam of electrons to traverse the evacuated interaction chamber. The device also contains a mechanism for feeding back a microwave electromagnetic field from the resonant cavity to the evacuated interaction chamber in such a way as to modulate the direction of propagation of the electron beam, thereby further amplifyjng the microwave electromagnetic field. Furthermore, provision is made for coupling the electromagnetic field out of the electron beam microwave device.

  19. Plasma lenses for focusing relativistic electron beams

    SciTech Connect

    Govil, R.; Wheeler, S.; Leemans, W.

    1997-04-01

    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{sub p} much greater than electron beam density, n{sub b}) or underdense (n{sub p} less than 2 n{sub 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.

  20. Electron beam effects in a UV FEL

    SciTech Connect

    Wong, R.K.; Blau, J.; Colson, W.B.

    1995-12-31

    At the Continuous Electron Beam Accelerator Facility (CEBAF), a free electron laser (FEL) is designed to produce ultraviolet (UV) light. A four-dimensional FEL simulation studies the effects of betatron oscillations, external focusing, and longitudinal pulse compression of the electron beam on the FEL performance.

  1. Rippled-beam free-electron laser

    SciTech Connect

    Carlsten, B.E.

    1997-10-01

    The authors describe a new microwave generation mechanism involving a scalloping annular electron beam. The beam interacts with the axial electric field of a TM{sub 0n} mode in a smooth circular waveguide through the axial free-electron laser interaction, in which the beam ripple period is synchronous with the phase slippage of the rf mode relative to the electron beam. Due to nonlinearities in the orbit equation, the interaction can be made autoresonant, where the phase and amplitude of the gain is independent of the beam energy.

  2. Towards demonstration of electron cooling with bunched electron beam

    SciTech Connect

    Fedotov, A.

    2012-01-11

    All electron cooling systems which were in operation so far employed electron beam generated with an electrostatic electron gun in DC operating mode, immersed in a longitudinal magnetic field. At low energies magnetic field is also being used to transport electron beam through the cooling section from the gun to the collector. At higher energies (few MeV), it was shown that one can have simpler electron beam transport without continuous magnetic field. Because of a rather weak magnetic field on the cathode and in the cooling section the latter approach was referred to as 'non-magnetized cooling', since there was no suppression of the transverse angular spread of the electron beam with the magnetic field in the cooling section. Such a cooler successfully operated at FNAL (2005-11) at electron beam energy of 4.3 MeV. Providing cooling at even higher energies would be easier with RF acceleration of electron beam, and thus using bunched electron beam for cooling. Significant efforts were devoted to explore various aspects of such bunched electron beam cooling as part of R and D of high-energy electron cooling for RHIC. However, experimental studies of such cooling are still lacking. Establishing this technique experimentally would be extremely useful for future high-energy applications. Presently there is an ongoing effort to build Proof-of-Principle (PoP) experiment of Coherent Electron Cooling (CEC) at RHIC, which promises to be superior to conventional electron cooling for high energies. Since the CEC experiment is based on bunched electron beam and it has sections where electron beam co-propagates with the ion beam at the same velocity, it also provides a unique opportunity to explore experimentally conventional electron cooling but for the first time with a bunched electron beam. As a result, it allows us to explore techniques needed for the high-energy electron cooling such as 'painting' with a short electron beam and control of ion beam distribution under

  3. Electron Systems Out of Equilibrium: Nonequilibrium Green's Function Approach

    NASA Astrophysics Data System (ADS)

    Špička, Václav Velický, Bedřich Kalvová, Anděla

    2015-10-01

    This review deals with the state of the art and perspectives of description of non-equilibrium many body systems using the non-equilibrium Green's function (NGF) method. The basic aim is to describe time evolution of the many-body system from its initial state over its transient dynamics to its long time asymptotic evolution. First, we discuss basic aims of transport theories to motivate the introduction of the NGF techniques. Second, this article summarizes the present view on construction of the electron transport equations formulated within the NGF approach to non-equilibrium. We discuss incorporation of complex initial conditions to the NGF formalism, and the NGF reconstruction theorem, which serves as a tool to derive simplified kinetic equations. Three stages of evolution of the non-equilibrium, the first described by the full NGF description, the second by a Non-Markovian Generalized Master Equation and the third by a Markovian Master Equation will be related to each other.

  4. Creating electron vortex beams with light.

    PubMed

    Handali, Jonathan; Shakya, Pratistha; Barwick, Brett

    2015-02-23

    We propose an all-optical method of creating electron vortices utilizing the Kapitza-Dirac effect. This technique uses the transfer of orbital angular momentum from photons to free electrons creating electron vortex beams in the process. The laser intensities needed for this experiment can be obtained with available pulsed lasers and the resulting electron beams carrying orbital angular momentum will be particularly useful in the study of magnetic materials and chiral plasmonic structures in ultrafast electron microscopy.

  5. The POSEIDON electron beam generator. Final report

    SciTech Connect

    Sethian, J.D.; Mora, F.

    1982-09-27

    The POSEIDON electron beam generator was designed to perform a series of experiments to produce a closed field line plasma confinement system with two rotating relativistic electron beams. Previous experimental studies have shown that a single rotating beam (generated by the TRITON electron beam generator) can produce a plasma in a reversed field configuration inside an initially field free metal tube. The magnetic fields were maintained with induced plasma currents rather than the beam electrons themselves. However, because the beam was injected from one end of the system, a net axial current persisted which precluded axial containment. To eliminate this current, it was proposed to inject a second rotating beam from the opposite end of the system.

  6. Precision Absolute Beam Current Measurement of Low Power Electron Beam

    SciTech Connect

    Ali, M. M.; Bevins, M. E.; Degtiarenko, P.; Freyberger, A.; Krafft, G. A.

    2012-11-01

    Precise measurements of low power CW electron beam current for the Jefferson Lab Nuclear Physics program have been performed using a Tungsten calorimeter. This paper describes the rationale for the choice of the calorimeter technique, as well as the design and calibration of the device. The calorimeter is in use presently to provide a 1% absolute current measurement of CW electron beam with 50 to 500 nA of average beam current and 1-3 GeV beam energy. Results from these recent measurements will also be presented.

  7. Focused electron and ion beam systems

    DOEpatents

    Leung, Ka-Ngo; Reijonen, Jani; Persaud, Arun; Ji, Qing; Jiang, Ximan

    2004-07-27

    An electron beam system is based on a plasma generator in a plasma ion source with an accelerator column. The electrons are extracted from a plasma cathode in a plasma ion source, e.g. a multicusp plasma ion source. The beam can be scanned in both the x and y directions, and the system can be operated with multiple beamlets. A compact focused ion or electron beam system has a plasma ion source and an all-electrostatic beam acceleration and focusing column. The ion source is a small chamber with the plasma produced by radio-frequency (RF) induction discharge. The RF antenna is wound outside the chamber and connected to an RF supply. Ions or electrons can be extracted from the source. A multi-beam system has several sources of different species and an electron beam source.

  8. Low energy electron magnetometer using a monoenergetic electron beam

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M.; Rayborn, G. H.; White, F. A. (Inventor)

    1983-01-01

    A low energy electron beam magnetometer utilizes near-monoenergetic electrons thereby reducing errors due to electron energy spread and electron nonuniform angular distribution. In a first embodiment, atoms in an atomic beam of an inert gas are excited to a Rydberg state and then electrons of near zero energy are detached from the Rydberg atoms. The near zero energy electrons are then accelerated by an electric field V(acc) to form the electron beam. In a second embodiment, a filament emits electrons into an electrostatic analyzer which selects electrons at a predetermined energy level within a very narrow range. These selected electrons make up the electron beam that is subjected to the magnetic field being measured.

  9. Electron beam emittance monitor for the SSC

    SciTech Connect

    Tsyganov, E.; Meinke, R.; Nexsen, W.; Kauffmann, S.; Zinchenko, A.; Taratin, A.

    1993-05-01

    A nondestructive beam profile monitor for the Superconducting Super Collider (SSC) is presented using as a probe a low-energy electron beam interacting with the proton bunch charge. Results using a full Monte Carlo simulation code look promising for the transverse and longitudinal beam profile measurements.

  10. Redesigned Electron-Beam Furnace Boosts Productivity

    NASA Technical Reports Server (NTRS)

    Williams, Gary A.

    1995-01-01

    Redesigned electron-beam furnace features carousel of greater capacity so more experiments conducted per loading, and time spent on reloading and vacuum pump-down reduced. Common mounting plate for electron source and carousel simplifies installation and reduces vibration.

  11. Feasibility study for mega-electron-volt electron beam tomography

    SciTech Connect

    Hampel, U.; Baertling, Y.; Hoppe, D.; Kuksanov, N.; Fadeev, S.; Salimov, R.

    2012-09-15

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  12. Feasibility study for mega-electron-volt electron beam tomography.

    PubMed

    Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

    2012-09-01

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  13. Ion-beam assisted, electron-beam physical vapor deposition

    SciTech Connect

    Singh, J.

    1996-12-01

    Electron beam-physical vapor deposition (EB-PVD) is a relatively new technology that has overcome some of the difficulties associated with chemical vapor deposition, physical vapor deposition, and thermal spray processes. In the EB-PVD process, focused high-energy electron beams generated from electron guns are directed to melt and evaporate ingots, as well as preheat the substrate inside a vacuum chamber. By adding the assistance of ion beams to the process, coating density and adhesion are improved, while costs are reduced. This article describes physical vapor deposition and ion-beam processes, explains the advantages of EB-PVD, shows how ion beams optimize the benefits of EB-PVD, and enumerates a variety of applications.

  14. Focused electron beam in pyroelectric electron probe microanalyzer.

    PubMed

    Imashuku, Susumu; Imanishi, Akira; Kawai, Jun

    2013-07-01

    We report a method to focus the electron beam generated using a pyroelectric crystal. An electron beam with a spot size of 100 μm was achieved by applying an electrical field to an electroconductive needle tip set on a pyroelectric crystal. When the focused electron beam bombarded a sample, characteristic X-rays of the sample were only detected due to the production of an electric field between the needle tip and the sample.

  15. Electron-positron pair equilibrium in strongly magnetized plasmas

    SciTech Connect

    Harding, A.K.

    1984-11-01

    Steady states of thermal electron-positron pair plasmas at mildly relativistic temperatures and in strong magnetic fields are investigated. The pair density in steady-state equilibrium, where pair production balances annihilation, is found as a function of temperature, magnetic field strength and source size, by a numerical calculation which includes pair production attenuation and Compton scattering of the photons. It is found that there is a maximum pair density for each value of temperature and field strength, and also a source size above which optically thin equilibrium states do not exist. (ESA)

  16. Wave excitation by inhomogeneous suprathermal electron beams

    NASA Technical Reports Server (NTRS)

    Freund, H. P.; Dillenburg, D.; Wu, C. S.

    1982-01-01

    Wave excitation by an inhomogeneous suprathermal electron beam in a homogeneous magnetized plasma is studied. Not only is the beam density nonuniform, but the beam electrons possess a sheared bulk velocity. The general dispersion equation encompassing both electrostatic and electromagnetic effects is derived. Particular attention is given to the whistler mode. It is established that the density-gradient and velocity-shear effects are important for waves with frequencies close to the lower-hybrid resonance frequency.

  17. Electron Beam Influence on Microcrystalline Cellulose

    NASA Astrophysics Data System (ADS)

    Nemţanu, Monica R.; Minea, R.; Mitru, Ecaterina

    2007-04-01

    Cellulose is a natural raw material used in great quantity as stabilizer, tabletting agent, anti-caking agent, flavor carrier, etc. Due to its structure it has limited uses exhibiting some disadvantages in certain applications. Irradiation technique is frequently used to change the polymeric materials. The purpose of the work is to discuss the action of accelerated electron beams (e-beams) on microcrystalline cellulose. The results of the study showed that some properties of cellulose can be improved by electron beam treatment.

  18. Intense steady state electron beam generator

    DOEpatents

    Hershcovitch, Ady; Kovarik, Vincent J.; Prelec, Krsto

    1990-01-01

    An intense, steady state, low emittance electron beam generator is formed by operating a hollow cathode discharge plasma source at critical levels in combination with an extraction electrode and a target electrode that are operable to extract a beam of fast primary electrons from the plasma source through a negatively biased grid that is critically operated to repel bulk electrons toward the plasma source while allowing the fast primary electrons to move toward the target in the desired beam that can be successfully transported for relatively large distances, such as one or more meters away from the plasma source.

  19. Optimizing the electron beam parameters for head-on beam-beam compensation in RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.; Pikin, A.; Gu, X.

    2011-03-28

    Head-on beam-beam compensation is adopted to compensate the large beam-beam tune spread from the protonproton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). Two e-lenses are being built and to be in stalled near IP10 in the end of 2011. In this article we perform numeric simulation to investigate the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse profile, size, current, offset and random errors in them. In this article we studied the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse shape, size, current, offset and their random errors. From the study, we require that the electron beam size can not be smaller than the proton beam's. And the random noise in the electron current should be better than 0.1%. The offset of electron beam w.r.t. the proton beam center is crucial to head-on beam-beam compensation. Its random errors should be below {+-}8{micro}m.

  20. NON-EQUILIBRIUM ELECTRONS IN THE OUTSKIRTS OF GALAXY CLUSTERS

    SciTech Connect

    Avestruz, Camille; Nagai, Daisuke; Lau, Erwin T.; Nelson, Kaylea E-mail: camille.avestruz@yale.edu

    2015-08-01

    The analysis of X-ray and Sunyaev–Zel’dovich measurements of the intracluster medium (ICM) assumes that electrons are in thermal equilibrium with ions in the plasma. However, in the outskirts of galaxy clusters, the electron–ion equilibration timescale can become comparable to the Hubble time, leading to systematic biases in cluster mass estimates and mass-observable scaling relations. To quantify an upper limit of the impact of non-equilibrium electrons, we use a mass-limited sample of simulated galaxy clusters taken from a cosmological simulation with a two-temperature model that assumes the Spitzer equilibration time for the electrons and ions. We show that the temperature bias is more pronounced in more massive and rapidly accreting clusters. For the most extreme case, we find that the bias is of the order of 10% at half of the cluster virial radius and increases to 40% at the edge of the cluster. Gas in filaments is less susceptible to the non-equilibrium effect, leading to azimuthal variations in the temperature bias at large cluster-centric radii. Using mock Chandra observations of simulated clusters, we show that the bias manifests in ultra-deep X-ray observations of cluster outskirts and quantify the resulting biases in hydrostatic mass and cluster temperature derived from these observations. We provide a mass-dependent fitting function for the temperature bias profile, which can be useful for modeling the effect of electron-ion equilibration in galaxy clusters.

  1. Dual cathode system for electron beam instruments

    NASA Technical Reports Server (NTRS)

    Bradley, James G. (Inventor); Conley, Joseph M. (Inventor); Wittry, David B. (Inventor)

    1989-01-01

    An electron beam source having a single electron optical axis is provided with two coplanar cathodes equally spaced on opposite sides from the electron optical axis. A switch permits selecting either cathode, and a deflection system comprised of electromagnets, each with separate pole pieces equally spaced from the plane of the cathodes and electron optical axis, first deflects the electron beam from a selected cathode toward the electron optical axis, and then in an opposite direction into convergence with the electron optical axis. The result is that the electron beam from one selected cathode undergoes a sigmoid deflection in two opposite directions, like the letter S, with the sigmoid deflection of each being a mirror image of the other.

  2. Single electron beam rf feedback free electron laser

    DOEpatents

    Brau, C.A.; Stein, W.E.; Rockwood, S.D.

    1981-02-11

    A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

  3. Attainment of Electron Beam Suitable for Medium Energy Electron Cooling

    SciTech Connect

    Seletskiy, Sergei M.

    2005-01-01

    Electron cooling of charged particle beams is a well-established technique at electron energies of up to 300 keV. However, up to the present time the advance of electron cooling to the MeV-range energies has remained a purely theoretical possibility. The electron cooling project at Fermilab has recently demonstrated the ¯rst cooling of 8.9 GeV/c antiprotons in the Recycler ring, and therefore, has proved the validity of the idea of relativistic electron cool- ing. The Recycler Electron Cooler (REC) is the key component of the Teva- tron Run II luminosity upgrade project. Its performance depends critically on the quality of electron beam. A stable electron beam of 4.3 MeV car- rying 0.5 A of DC current is required. The beam suitable for the Recycler Electron Cooler must have an angular spread not exceeding 200 ¹rad. The full-scale prototype of the REC was designed, built and tested at Fermilab in the Wideband laboratory to study the feasibility of attaining the high-quality electron beam. In this thesis I describe various aspects of development of the Fermilab electron cooling system, and the techniques used to obtain the electron beam suitable for the cooling process. In particular I emphasize those aspects of the work for which I was principally responsible.

  4. Kinetic-MHD hybrid equilibrium model using a Monte-Carlo calculation of runaway electron distribution function

    NASA Astrophysics Data System (ADS)

    Matsuyama, Akinobu; Aiba, Nobuyuki; Yagi, Masatoshi

    2015-11-01

    An axisymmetric MHD equilibrium model is studied to allow the inclusion of both beam inertia and energy spectrum for runaway electron beam. Following kinetic-MHD hybrid approach, we evaluate the RE beam current from the integrals of the RE distribution function. The distribution function is here evaluated by a relativistic guiding-center trace code ETC-Rel, where we have implemented the effects of collisions, radiations, and exponential growth into the code. Because to directly treat the Dreicer mechanism in particle simulations is time consuming, the primary RE source is modeled by a Monte-Carlo weighing scheme taking into account the instantaneous generation rate. This paper applies ETC-Rel to the parametric study of the MHD equilibrium with different RE beam parameters. Kinetic effects on the MHD equilibrium appears, e.g., as enhanced Shafranov shifts due to the inertia of highly relativistic electrons. A kinetic modification to the equilibrium becomes significant if the contribution of the beam inertia - being increased with the total electron mass of multi-MeV RE populations - becomes large enough to affect the radial force balance. This work was supported in part by MEXT KAKENHI Grant No. 23561009 and 26820404.

  5. Warm-fluid description of intense beam equilibrium and electrostatic stability properties

    SciTech Connect

    Lund, S.M.; Davidson, R.C.

    1998-08-01

    A nonrelativistic warm-fluid model is employed in the electrostatic approximation to investigate the equilibrium and stability properties of an unbunched, continuously focused intense ion beam. A closed macroscopic model is obtained by truncating the hierarchy of moment equations by the assumption of negligible heat flow. Equations describing self-consistent fluid equilibria are derived and elucidated with examples corresponding to thermal equilibrium, the Kapchinskij{endash}Vladimirskij (KV) equilibrium, and the waterbag equilibrium. Linearized fluid equations are derived that describe the evolution of small-amplitude perturbations about an arbitrary equilibrium. Electrostatic stability properties are analyzed in detail for a cold beam with step-function density profile, and then for axisymmetric flute perturbations with {partial_derivative}/{partial_derivative}{theta}=0 and {partial_derivative}/{partial_derivative}z=0 about a warm-fluid KV beam equilibrium. The radial eigenfunction describing axisymmetric flute perturbations about the KV equilibrium is found to be {ital identical} to the eigenfunction derived in a full kinetic treatment. However, in contrast to the kinetic treatment, the warm-fluid model predicts stable oscillations. None of the instabilities that are present in a kinetic description are obtained in the fluid model. A careful comparison of the mode oscillation frequencies associated with the fluid and kinetic models is made in order to delineate which stability features of a KV beam are model-dependent and which may have general applicability. {copyright} {ital 1998 American Institute of Physics.}

  6. Electron Beam Scanning in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Jongen, Yves; Herer, Arnold

    1996-05-01

    Scanned electron beams are used within many industries for applications such as sterilization of medical disposables, crosslinking of wire and cables insulating jackets, polymerization and degradation of resins and biomaterials, modification of semiconductors, coloration of gemstones and glasses, removal of oxides from coal plant flue gasses, and the curing of advanced composites and other molded forms. X-rays generated from scanned electron beams make yet other applications, such as food irradiation, viable. Typical accelerators for these applications range in beam energy from 0.5MeV to 10 MeV, with beam powers between 5 to 500kW and scanning widths between 20 and 300 cm. Since precise control of dose delivery is required in many of these applications, the integration of beam characteristics, product conveyance, and beam scanning mechanisms must be well understood and optimized. Fundamental issues and some case examples are presented.

  7. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron`s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  8. Non-Vacuum Electron Beam Welding

    SciTech Connect

    Hershcovitch, Ady

    2007-01-31

    Original objectives of CRADA number BNL-01-03 between BNL and Acceleron, Inc., were to further develop the Plasma Window concept (a BNL invention covered by US Patent number 5,578,831), mate the Plasma Window to an existing electron beam welder to perform in-air electron beam welding, and mount the novel nonvacuum electron beam welder on a robot arm. Except for the last objective, all other goals were met or exceeded. Plasma Window design and operation was enhanced during the project, and it was successfully mated to a conventional4 kW electron beam welder. Unprecedented high quality non-vacuum electron beam . welding was demonstrated. Additionally, a new invention the Plasma Shield (US Patent number 7,075,030) that chemically and thermally shields a target object was set forth. Great interest in the new technology was shown by a number of industries and three arcs were sold for experimental use. However, the welding industry requested demonstration of high speed welding, which requires 100 kW electron beam welders. The cost of such a welder involved the need for additional funding. Therefore, some of the effort was directed towards Plasma Shield development. Although relatively a small portion of the R&D effort was spent on the Plasma Shield, some very encouraging results were obtained. Inair Plasma Shield was demonstrated. With only a partial shield, enhanced vacuum separation and cleaner welds were realized. And, electron beam propagation in atmosphere improved by a factor of about 3. Benefits to industry are the introduction of two new technologies. BNL benefited from licensing fee cash, from partial payment for employee salary, and from a new patent In addition to financial benefits, a new technology for physics studies was developed. Recommendations for future work are to develop an under-water plasma shield, perform welding with high-power electron beam:s, carry out other plasma shielded electron beam and laser processes. Potential benefits from further R

  9. Intense Relativistic Electron Beam Investigations

    DTIC Science & Technology

    1979-04-01

    flashover and other undetermined physical processes which create a plasma at the liner surface . The ions are drawn toward the Uiner axis by the...dielectric wall and causing surface flashover and the liberation of ions. These ions provide sufficient charge neutralization for the beam to propagate a...beam-induced surface flashover process which produces the ions to be accelerated. Alternative methods are proposed in Section III for next year’s

  10. Electron beam machining using rotating and shaped beam power distribution

    DOEpatents

    Elmer, John W.; O'Brien, Dennis W.

    1996-01-01

    An apparatus and method for electron beam (EB) machining (drilling, cutting and welding) that uses conventional EB guns, power supplies, and welding machine technology without the need for fast bias pulsing technology. The invention involves a magnetic lensing (EB optics) system and electronic controls to: 1) concurrently bend, focus, shape, scan, and rotate the beam to protect the EB gun and to create a desired effective power-density distribution, and 2) rotate or scan this shaped beam in a controlled way. The shaped beam power-density distribution can be measured using a tomographic imaging system. For example, the EB apparatus of this invention has the ability to drill holes in metal having a diameter up to 1000 .mu.m (1 mm or larger), compared to the 250 .mu.m diameter of laser drilling.

  11. Electron beam machining using rotating and shaped beam power distribution

    DOEpatents

    Elmer, J.W.; O`Brien, D.W.

    1996-07-09

    An apparatus and method are disclosed for electron beam (EB) machining (drilling, cutting and welding) that uses conventional EB guns, power supplies, and welding machine technology without the need for fast bias pulsing technology. The invention involves a magnetic lensing (EB optics) system and electronic controls to: (1) concurrently bend, focus, shape, scan, and rotate the beam to protect the EB gun and to create a desired effective power-density distribution, and (2) rotate or scan this shaped beam in a controlled way. The shaped beam power-density distribution can be measured using a tomographic imaging system. For example, the EB apparatus of this invention has the ability to drill holes in metal having a diameter up to 1,000 {micro}m (1 mm or larger), compared to the 250 {micro}m diameter of laser drilling. 5 figs.

  12. Numerical simulation of electron beam welding with beam oscillations

    NASA Astrophysics Data System (ADS)

    Trushnikov, D. N.; Permyakov, G. L.

    2017-02-01

    This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.

  13. Runaway electron beam in atmospheric pressure discharges

    NASA Astrophysics Data System (ADS)

    Oreshkin, E. V.; Barengolts, S. A.; Chaikovsky, S. A.; Oreshkin, V. I.

    2015-11-01

    A numerical simulation was performed to study the formation of a runaway electron (RAE) beam from an individual emission zone in atmospheric pressure air discharges with a highly overvolted interelectrode gap. It is shown that the formation of a RAE beam in discharges at high overvoltages is much contributed by avalanche processes.

  14. Emittance growth from electron beam modulation

    SciTech Connect

    Blaskiewicz, M.

    2009-12-01

    In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

  15. Scrap uranium recycling via electron beam melting

    SciTech Connect

    McKoon, R.

    1993-11-01

    A program is underway at the Lawrence Livermore National Laboratory (LLNL) to recycle scrap uranium metal. Currently, much of the material from forging and machining processes is considered radioactive waste and is disposed of by oxidation and encapsulation at significant cost. In the recycling process, uranium and uranium alloys in various forms will be processed by electron beam melting and continuously cast into ingots meeting applicable specifications for virgin material. Existing vacuum processing facilities at LLNL are in compliance with all current federal and state environmental, safety and health regulations for the electron beam melting and vaporization of uranium metal. One of these facilities has been retrofitted with an auxiliary electron beam gun system, water-cooled hearth, crucible and ingot puller to create an electron beam melt furnace. In this furnace, basic process R&D on uranium recycling will be performed with the goal of eventual transfer of this technology to a production facility.

  16. The Electron Beam Ion Source (EBIS)

    ScienceCinema

    Brookhaven Lab

    2016-07-12

    Brookhaven National Lab has successfully developed a new pre-injector system, called the Electron Beam Ion Source, for the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory science programs. The first of several planned improvemen

  17. Photon-Electron Interaction and Condense Beams

    SciTech Connect

    Chattopadhyay, S.

    1998-11-01

    We discuss beams of charged particles and radiation from multiple perspectives. These include fundamental acceleration and radiation mechanisms, underlying electron-photon interaction, various classical and quantum phase-space concepts and fluctuational interpretations.

  18. Electron beam depolarization in a damping ring

    SciTech Connect

    Minty, M.

    1993-04-01

    Depolarization of a polarized electron beam injected into a damping ring is analyzed by extending calculations conventionally applied to proton synchrotrons. Synchrotron radiation in an electron ring gives rise to both polarizing and depolarizing effects. In a damping ring, the beam is stored for a time much less than the time for self polarization. Spin flip radiation may therefore be neglected. Synchrotron radiation without spin flips, however, must be considered as the resonance strength depends on the vertical betatron oscillation amplitude which changes as the electron beam is radiation damped. An expression for the beam polarization at extraction is derived which takes into account radiation damping. The results are applied to the electron ring at the Stanford Linear Collider and are compared with numerical matrix formalisms.

  19. Technical Seminar: Electron Beam Forming Fabrication

    NASA Video Gallery

    EBF³ uses a focused electron beam in a vacuum environment to create a molten pool on a metallic substrate. This layer-additive process enables fabrication of parts directly from CAD drawings. The ...

  20. The Electron Beam Ion Source (EBIS)

    SciTech Connect

    Brookhaven Lab

    2009-06-09

    Brookhaven National Lab has successfully developed a new pre-injector system, called the Electron Beam Ion Source, for the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory science programs. The first of several planned improvemen

  1. Electron-Beam Dynamics for an Advanced Flash-Radiography Accelerator

    SciTech Connect

    Ekdahl, Carl

    2015-11-17

    Beam dynamics issues were assessed for a new linear induction electron accelerator being designed for multipulse flash radiography of large explosively driven hydrodynamic experiments. Special attention was paid to equilibrium beam transport, possible emittance growth, and beam stability. Especially problematic would be high-frequency beam instabilities that could blur individual radiographic source spots, low-frequency beam motion that could cause pulse-to-pulse spot displacement, and emittance growth that could enlarge the source spots. Furthermore, beam physics issues were examined through theoretical analysis and computer simulations, including particle-in-cell codes. Beam instabilities investigated included beam breakup, image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. The beam corkscrew motion and emittance growth from beam mismatch were also studied. It was concluded that a beam with radiographic quality equivalent to the present accelerators at Los Alamos National Laboratory will result if the same engineering standards and construction details are upheld.

  2. Electron-beam dynamics for an advanced flash-radiography accelerator

    SciTech Connect

    Ekdahl, Carl August Jr.

    2015-06-22

    Beam dynamics issues were assessed for a new linear induction electron accelerator. Special attention was paid to equilibrium beam transport, possible emittance growth, and beam stability. Especially problematic would be high-frequency beam instabilities that could blur individual radiographic source spots, low-frequency beam motion that could cause pulse-to-pulse spot displacement, and emittance growth that could enlarge the source spots. Beam physics issues were examined through theoretical analysis and computer simulations, including particle-in cell (PIC) codes. Beam instabilities investigated included beam breakup (BBU), image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. Beam corkscrew motion and emittance growth from beam mismatch were also studied. It was concluded that a beam with radiographic quality equivalent to the present accelerators at Los Alamos will result if the same engineering standards and construction details are upheld.

  3. Ion beam processing of advanced electronic materials

    SciTech Connect

    Cheung, N.W.; Marwick, A.D.; Roberto, J.B.; International Business Machines Corp., Yorktown Heights, NY . Thomas J. Watson Research Center; Oak Ridge National Lab., TN )

    1989-01-01

    This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases. (CBS)

  4. Electron Cooling of Intense Ion Beam

    SciTech Connect

    Dietrich, J.; Kamerdjiev, V.; Maier, R.; Prasuhn, D.; Stein, J.; Stockhorst, H.; Korotaev, Yu.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2006-03-20

    Results of experimental studies of the electron cooling of a proton beam at COSY (Juelich, Germany) are presented. Intensity of the proton beam is limited by two general effects: particle loss directly after the injection and development of instability in a deep cooled ion beam. Results of the instability investigations performed at COSY during last years are presented in this report in comparison with previous results from HIMAC (Chiba, Japan) CELSIUS (Uppsala, Sweden) and LEAR (CERN). Methods of the instability suppression, which allow increasing the cooled beam intensity, are described. This work is supported by RFBR grant no. 05-02-16320 and INTAS grant no. 03-54-5584.

  5. NUMERICAL SOLUTION FOR THE POTENTIAL AND DENSITY PROFILE OF A THERMAL EQUILIBRIUM SHEET BEAM

    SciTech Connect

    Lund, S M; Bazouin, G

    2011-03-29

    In a recent paper, S. M. Lund, A. Friedman, and G. Bazouin, Sheet beam model for intense space-charge: with application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam, in press, Phys. Rev. Special Topics - Accel. and Beams (2011), a 1D sheet beam model was extensively analyzed. In this complementary paper, we present details of a numerical procedure developed to construct the self-consistent electrostatic potential and density profile of a thermal equilibrium sheet beam distribution. This procedure effectively circumvents pathologies which can prevent use of standard numerical integration techniques when space-charge intensity is high. The procedure employs transformations and is straightforward to implement with standard numerical methods and produces accurate solutions which can be applied to thermal equilibria with arbitrarily strong space-charge intensity up to the applied focusing limit.

  6. NUMERICAL SOLUTION FOR THE POTENTIAL AND DENSITY PROFILE OF A THERMAL EQUILIBRIUM SHEET BEAM

    SciTech Connect

    Bazouin, Steven M. Lund, Guillaume; Bazouin, Guillaume

    2011-04-01

    In a recent paper, S. M. Lund, A. Friedman, and G. Bazouin, Sheet beam model for intense space-charge: with application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam, in press, Phys. Rev. Special Topics - Accel. and Beams (2011), a 1D sheet beam model was extensively analyzed. In this complementary paper, we present details of a numerical procedure developed to construct the self-consistent electrostatic potential and density profile of a thermal equilibrium sheet beam distribution. This procedure effectively circumvents pathologies which can prevent use of standard numerical integration techniques when space-charge intensity is high. The procedure employs transformations and is straightforward to implement with standard numerical methods and produces accurate solutions which can be applied to thermal equilibria with arbitrarily strong space-charge intensity up to the applied focusing limit.

  7. A reflex electron beam discharge as a plasma source for electron beam generation

    SciTech Connect

    Murray, C.S.; Rocca, J.J.; Szapiro, B. )

    1988-10-01

    A reflex electron beam glow discharge has been used as a plasma source for the generation of broad-area electron beams. An electron current of 120 A (12 A/cm/sup 2/) was extracted from the plasma in 10 ..mu..s pulses and accelerated to energies greater than 1 keV in the gap between two grids. The scaling of the scheme for the generation of multikiloamp high-energy beams is discussed.

  8. Control and Manipulation of Electron Beams

    SciTech Connect

    Piot, Philippe

    2009-01-22

    The concepts of the advanced accelerators and light source rely on the production of bright electron beams. The rms areas of the beam phase space often need to be tailored to the specific applications. Furthermore, a new class of the forefront research calls for detailed specific distribution such as the particle density in the time coordinate. Several groups are tackling these various challenges and in this report we attempt to give a review of the state-of-the-art of the control and manipulation of the electron beams.

  9. A conceptual design for an electron beam

    SciTech Connect

    Garcia, M

    1999-02-15

    This report is a brief description of a model electron beam, which is meant to serve as a pulsed heat source that vaporizes a metal fleck into an ''under-dense'' cloud. See Reference 1. The envelope of the electron beam is calculated from the paraxial ray equation, as stated in Reference 2. The examples shown here are for 5 A, 200 keV beams that focus to waists of under 0.4 mm diameter, within a cylindrical volume of 10 cm radius and length. The magnetic fields assumed in the examples are moderate, 0.11 T and 0.35 T, and can probably be created by permanent magnets.

  10. Control and manipulation of electron beams

    SciTech Connect

    Piot, Philippe; /NICADD, DeKalb /Northern Illinois U. /Fermilab

    2008-09-01

    The concepts of the advanced accelerators and light source rely on the production of bright electron beams. The rms areas of the beam phase space often need to be tailored to the specific applications. Furthermore, a new class of the forefront research calls for detailed specific distribution such as the particle density in the time coordinate. Several groups are tackling these various challenges and in this report we attempt to give a review of the state-of-the-art of the control and manipulation of the electron beams.

  11. Short rise time intense electron beam generator

    DOEpatents

    Olson, Craig L.

    1987-01-01

    A generator for producing an intense relativistic electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  12. Short rise time intense electron beam generator

    DOEpatents

    Olson, C.L.

    1984-03-16

    A generator for producing an intense relativisitc electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  13. Laser-Bessel-Beam-Driven Electron Acceleration

    NASA Astrophysics Data System (ADS)

    Li, Dazhi; Imasaki, Kazuo

    2005-08-01

    A vacuum-laser-driven acceleration scheme using a laser Bessel beam is presented. In contrast to the conventional Gaussian beam, the Bessel beam demonstrates diffraction-free propagation, which implies the possibility of extending the effective interaction distance for a laser-electron system. In this method, the Bessel beam is truncated by annular slits to realize a series of nonsuccessive dim regions along the path of laser propagation, where the amplitude of the laser field is reduced, making the electron slightly decelerate as it travels in the decelerating phase. We analyzed the propagation characteristics of the truncated Bessel beam with scalar diffraction theory, and then introduced this approach with careful investigation of a three-stage acceleration model.

  14. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  15. Funneling electron beams from gallium arsenide photocathodes

    NASA Astrophysics Data System (ADS)

    Rahman, Omer Habib

    Gallium Arsenide (GaAs) is the most widely used source of polarized electrons around the world. Electrons are extracted from a GaAs surface, terminated by a cesium-oxygen layer. The electrons are accelerated to form a beam by a DC electric field. This beam can ionize residual gas in the chamber, and the DC field accelerates the resulting ions into the cathode surface, damaging the Cesium- Oxygen layer. This process, called Ion Back Bombardment, is the dominant mechanism for limiting photocathode lifetime. As a result, high average current operation yields charge lifetimes too low to be used in a collider design. One idea to extend the charge lifetime is to funnel the beams from multiple cathodes using a rotating magnetic field-if operation of one cathode does not affect the operation of another cathode in the same chamber, then the source's lifetime can be extended by simply adding more cathodes. This dissertation presents the design, construction and commissioning of a unique electron gun capable of operating twenty cathodes. Results of funneling two electron beams with a rotating magnetic field are also presented. For average currents at 175 nA and 350 nA, the charge lifetimes for individual cathodes and two-cathode operation were measured, showing that the charge lifetime for two beam funneling is the sum of the individual ion back bombardment charge lifetimes. The addition of charge lifetime implies that beam funneling can be used to increase charge lifetime by an order of magnitude.

  16. Electron beam direct write: shaped beam overcomes resolution concerns

    NASA Astrophysics Data System (ADS)

    Stolberg, Ines; Pain, Laurent; Kretz, Johannes; Boettcher, Monika; Doering, Hans-Joachim; Gramss, Juergen; Hahmann, Peter

    2007-02-01

    In semiconductor industry time to market is one of the key success factors. Therefore fast prototyping and low-volume production will become extremely important for developing process technologies that are well ahead of the current technological level. Electron Beam Lithography has been launched for industrial use as a direct write technology for these types of applications. However, limited throughput rates and high tool complexity have been seen as the major concerns restricting the industrial use of this technology. Nowadays this begins to change. Variable Shaped Beam (VSB) writers have been established in Electron Beam Direct Write (EBDW) on Si or GaAs. In the paper semiconductor industry requirements to EBDW will be outlined. Behind this background the Vistec SB3050 lithography system will be reviewed. The achieved resolution enhancement of the VSB system down to the 22nm node exposure capability will be discussed in detail; application examples will be given. Combining EBDW in a Mix and Match technology with optical lithography is one way to utilize the high flexibility advantage of this technology and to overcome existing throughput concerns. However, to some extend a common Single Electron Beam Technology (SBT) will always be limited in throughput. Therefore Vistec's approach of a system that is based on the massive parallelisation of beams (MBT), which was initially pursued in a European Project, will also be discussed.

  17. Correlation in a coherent electron beam

    SciTech Connect

    Kodama, Tetsuji; Osakabe, Nobuyuki; Tonomura, Akira

    2011-06-15

    Correlations between successive detections in beams of free electrons are studied with a transmission electron microscope. For incoherent illumination of the detectors, a certain random coincidence probability is observed, indicative for uncorrelated arrival times of the electrons. When the illumination is changed from incoherent to coherent, a reduction of the random coincidence probability is observed, indicative for antibunching in the arrival times of the electrons. However, the amount of reduction is larger than the theoretically expected value calculated from the Pauli principle, forbidding more than one identical fermion to occupy the same quantum state. For a certain coherent illumination of the detectors, where we use magnetic lenses in electron microscopes for magnifications of the coherence length, we find an enhanced coincidence probability, indicative for bunching in the arrival times of the electrons. This originates from correlations in beams of free electrons due to Coulomb interactions.

  18. Holographic generation of highly twisted electron beams.

    PubMed

    Grillo, Vincenzo; Gazzadi, Gian Carlo; Mafakheri, Erfan; Frabboni, Stefano; Karimi, Ebrahim; Boyd, Robert W

    2015-01-23

    Free electrons can possess an intrinsic orbital angular momentum, similar to those in an electron cloud, upon free-space propagation. The wave front corresponding to the electron's wave function forms a helical structure with a number of twists given by the angular speed. Beams with a high number of twists are of particular interest because they carry a high magnetic moment about the propagation axis. Among several different techniques, electron holography seems to be a promising approach to shape a conventional electron beam into a helical form with large values of angular momentum. Here, we propose and manufacture a nanofabricated phase hologram for generating a beam of this kind with an orbital angular momentum up to 200ℏ. Based on a novel technique the value of orbital angular momentum of the generated beam is measured and then compared with simulations. Our work, apart from the technological achievements, may lead to a way of generating electron beams with a high quanta of magnetic moment along the propagation direction and, thus, may be used in the study of the magnetic properties of materials and for manipulating nanoparticles.

  19. Ribbon electron beam formation by a forevacuum plasma electron source

    SciTech Connect

    Klimov, A. S. Burdovitsin, V. A.; Grishkov, A. A.; Oks, E. M.; Zenin, A. A.; Yushkov, Yu. G.

    2016-01-15

    Results of the numerical analysis and experimental research on ribbon electron beam generation based on hollow cathode discharge at forevacuum gas pressure are presented. Geometry of the accelerating gap has modified. It lets us focus the ribbon electron beam and to transport it on a distance of several tens of centimeters in the absence of an axial magnetic field. The results of numerical simulations are confirmed by the experiment.

  20. Modelling of electron beam induced nanowire attraction

    NASA Astrophysics Data System (ADS)

    Bitzer, Lucas A.; Speich, Claudia; Schäfer, David; Erni, Daniel; Prost, Werner; Tegude, Franz J.; Benson, Niels; Schmechel, Roland

    2016-04-01

    Scanning electron microscope (SEM) induced nanowire (NW) attraction or bundling is a well known effect, which is mainly ascribed to structural or material dependent properties. However, there have also been recent reports of electron beam induced nanowire bending by SEM imaging, which is not fully explained by the current models, especially when considering the electro-dynamic interaction between NWs. In this article, we contribute to the understanding of this phenomenon, by introducing an electro-dynamic model based on capacitor and Lorentz force interaction, where the active NW bending is stimulated by an electromagnetic force between individual wires. The model includes geometrical, electrical, and mechanical NW parameters, as well as the influence of the electron beam source parameters and is validated using in-situ observations of electron beam induced GaAs nanowire (NW) bending by SEM imaging.

  1. Dispersion characteristics of the electromagnetic waves in a relativistic electron beam guided by the ion channel

    SciTech Connect

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Ghasemi, Maede; Sedaghat, Zeinab; Mahdian, Zeinab

    2010-05-15

    In this article, the dispersion characteristics of the paraxial (near axis) electromagnetic (EM) waves in a relativistic electron beam guided by the ion channel are investigated. Equilibrium fields such as ion-channel electrostatic field and self-fields of relativistic electron beam are included in this formalism. In accordance with the equilibrium field structure, radial and azimuthal waves are selected as base vectors for EM waves. It is shown that the dispersion of the radially polarized EM and space charge waves are influenced by the equilibrium fields, but azimuthally polarized wave remain unaffected. In some wave number domains, the radially polarized EM and fast space charge waves are coupled. In these regions, instability is analyzed as a function of equilibrium structure. It is shown that the total equilibrium radial force due to the ion channel and electron beam and also relativistic effect play a key role in the coupling of the radially polarized EM wave and space charge wave. Furthermore, some asymptotic behaviors such as weak and strong ion channel, nonrelativistic case and cutoff frequencies are discussed. This instability could be used as an amplification mechanism for radially polarized EM waves in a beam-plasma system where a relativistic electron beam is guided by the ion channel.

  2. Thermodynamic modelling of phase equilibrium in system Ti-B-Si-C, synthesis and phases composition of borides and carbides layers on titanic alloyVT-1 at electron beam treatment in vacuum

    NASA Astrophysics Data System (ADS)

    Smirnyagina, N. N.; Khaltanova, V. M.; Lapina, A. E.; Dasheev, D. E.

    2017-01-01

    Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VT-1 are generated at diffused saturation in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

  3. Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

    SciTech Connect

    Hastings, J.B.; Rudakov, F.M.; Dowell, D.H.; Schmerge, J.F.; Cardoza, J.D.; Castro, J.M.; Gierman, S.M.; Loos, H.; Weber, P.M.; /Brown U.

    2006-10-24

    An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.

  4. Scaling of Electron Beam Switches

    DTIC Science & Technology

    1983-06-01

    BEAM CURRENT DENSITY (AFTER FOIL). N2 760 Torr N2+0.038Torr C3F8 ~15 N2+0. l’T orr C3F8 N2+0. 124Torr C2F6 Ql L L 310 \\ ~ \\\\ ~ 5 h...Time [sec] FIG 5. CURRENT DECAYS FOR NITROGEN AND NITROGEN WITH ADDED ATTACHING GASES. CH4 760 Torr CH4+0. lTorr C2F6 CH4+0. lTorr C3F8 CH4

  5. High Density Mastering Using Electron Beam

    NASA Astrophysics Data System (ADS)

    Kojima, Yoshiaki; Kitahara, Hiroaki; Kasono, Osamu; Katsumura, Masahiro; Wada, Yasumitsu

    1998-04-01

    A mastering system for the next-generation digital versatile disk (DVD) is required to have a higher resolution compared with the conventional mastering systems. We have developed an electron beam mastering machine which features a thermal field emitter and a vacuum sealed air spindle motor. Beam displacement caused by magnetic fluctuation with spindle rotation was about 60 nm(p-p) in both the radial and tangential directions. Considering the servo gain of a read-out system, it has little influence on the read-out signal in terms of tracking errors and jitters. The disk performance was evaluated by recording either the 8/16 modulation signal or a groove on the disk. The electron beam recording showed better jitter values from the disk playback than those from a laser beam recorder. The deviation of track pitch was 44 nm(p-p). We also confirmed the high density recording with a capacity reaching 30 GB.

  6. Self-effect in expanding electron beam plasma

    SciTech Connect

    Garcia, M

    1999-05-07

    An analytical model of plasma flow from a metal plate hit by an intense, pulsed, electron beam aims to bridge the gap between radiation-hydrodynamics simulations and experiments, and to quantify the self-effect of the electron beam penetrating the flow. Does the flow disrupt the tight focus of the initial electron bunch, or later pulses in a train? This work aims to model the spatial distribution of plasma speed, density, degree of ionization, and magnetization to inquire. The initial solid density, several eV plasma expands to 1 cm and 10{sup {minus}4} relative density by 2 {micro}s, beyond which numerical simulations are imprecise. Yet, a Faraday cup detector at the ETA-II facility is at 25 cm from the target and observes the flow after 50 {micro}s. The model helps bridge this gap. The expansion of the target plasma into vacuum is so rapid that the ionized portion of the flow departs from local thermodynamic equilibrium. When the temperature (in eV) in a parcel of fluid drops below V{sub i} x [(2{gamma} - 2)/(5{gamma} + 17)], where V{sub i} is the ionization potential of the target metal (7.8 eV for tantalum), and {gamma} is the ratio of specific heats (5/3 for atoms), then the fractional ionization and electron temperature in that parcel remain fixed during subsequent expansion. The freezing temperature as defined here is V{sub i}/19. The balance between the self-pinching force and the space charge repulsion of an electron beam changes on penetrating a flow: (i) the target plasma cancels the space-charge field, (ii) internal eddy currents arise to counter the magnetization of relativistic electrons, and (iii) electron beam heating alters the flow magnetization by changing the plasma density gradient and the magnitude of the conductivity.

  7. Linac Coherent Light Source Electron Beam Collimation

    SciTech Connect

    Wu, J.; Dowell, D.; Emma, P.; Limborg-Deprey, C.; Schmerge, J.F.; /SLAC

    2007-04-27

    This paper describes the design and simulation of the electron beam collimation system in the Linac Coherent Light Source (LCLS). Dark current is expected from the gun and some of the accelerating cavities. Particle tracking of the expected dark current through the entire LCLS linac, from gun through FEL undulator, is used to estimate final particle extent in the undulator as well as expected beam loss at each collimator or aperture restriction. A table of collimators and aperture restrictions is listed along with halo particle loss results, which includes an estimate of average continuous beam power lost. In addition, the transverse wakefield alignment tolerances are calculated for each collimator.

  8. Fast magnetospheric echoes of energetic electron beams

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

    1983-01-01

    Electron beam experiments using rocket-borne instrumentation confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. A total of 234 echoes were observed in a pitch angle range from 9 to 110 deg at energies of 1.87 and 3.90 keV. Of these, 102 echoes could unambiguously be identified with known accelerator operations at 2, 4 or 8 keV energy and highest current levels resulting in the determination of transit times of typically 300 to 400 ms. In most cases, when echoes were present in both energy channels, the higher energy electrons led the lower energy ones by 50 to 70 ms. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. The injection process is discussed as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection.

  9. Picosecond runaway electron beams in air

    SciTech Connect

    Mesyats, G. A.; Yalandin, M. I.; Reutova, A. G.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.

    2012-01-15

    Experimental data on the generation of picosecond runaway electron beams in an air gap with an inhomogeneous electric field at a cathode voltage of up to 500 kV are presented. The methods and equipment developed for these experiments made it possible to measure the beam characteristics with a time resolution of better than 10{sup -11} s, determine the voltage range and the beam formation time in the breakdown delay stage, and demonstrate the influence of the state of the cathode surface on the stability of runaway electron generation. It is demonstrated that the critical electron runaway field in air agrees with the classical concepts and that the accelerated beam can be compressed to {approx}20 ps. It is unlikely that, under these conditions, the beam duration is limited due to the transition of field emission from the cathode to a microexplosion of inhomogeneities. The maximum energy acquired by runaway electrons in the course of acceleration does not exceed the value corresponding to the electrode voltage.

  10. Microwave Emission from Relativistic Electron Beams

    DTIC Science & Technology

    1989-03-01

    crucial for the operation of short wavelength free-electron lasers. It mitigates the effects of diffraction and thereby allows the free electron...akin to the guiding properties of an optical fiber. Such "optical guiding" [5]-[10] would mitigate the effects of diffraction, and thereby allow the...beam aperture limits the size of the beam to rb/ 1, f 0.07, the wiggler field is close to that of an ideal wiggler. That is, the effects of the radial

  11. Electron beam induced growth of tin whiskers

    SciTech Connect

    Vasko, A. C.; Karpov, V. G.; Warrell, G. R.; Parsai, E. I.; Shvydka, Diana

    2015-09-28

    We have investigated the influence of electron irradiation on tin whisker growth. Sputtered tin samples exposed to electron beam of 6 MeV energy exhibited fast whisker growth, while control samples did not grow any whiskers. The statistics of e-beam induced whiskers was found to follow the log-normal distribution. The observed accelerated whisker growth is attributed to electrostatic effects due to charges trapped in an insulating substrate. These results offer promise for establishing whisker-related accelerated life testing protocols.

  12. LOW EMITTANCE ELECTRON BEAMS FOR THE RHIC ELECTRON COOLER

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    An electron cooler, based on an Energy Recovery Linac (ERL) is under development for the Relativistic Heavy Ion Collider (RMIC) at Brookhaven National Laboratory. This will be the first electron cooler operating at high energy with bunched beams. In order to achieve sufficient cooling of the ion beams the electron have to have a charge of 5 nC and a normalized emittance less than 4 {mu}. This paper presents the progress in optimizing the injector and the emittance improvements from shaping the charge distribution in the bunch.

  13. Electron Beam Control of Combustion

    DTIC Science & Technology

    2006-11-01

    FA8655-03-D-0001, Delivery Order 0011 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dr. Georgy Pozdnyakov 5d. PROJECT NUMBER 5d...and Applied Mechanics SB RAS Project Director Dr. Georgy A. Pozdnyakov Novosibirsk, 2006...of the reaction region in the field of wavelengths of about 310 nm, for the kerosene-oxygen mixture. The moment of electron gun connection almost

  14. Electron beam diagnostic for profiling high power beams

    DOEpatents

    Elmer, John W.; Palmer, Todd A.; Teruya, Alan T.

    2008-03-25

    A system for characterizing high power electron beams at power levels of 10 kW and above is described. This system is comprised of a slit disk assembly having a multitude of radial slits, a conducting disk with the same number of radial slits located below the slit disk assembly, a Faraday cup assembly located below the conducting disk, and a start-stop target located proximate the slit disk assembly. In order to keep the system from over-heating during use, a heat sink is placed in close proximity to the components discussed above, and an active cooling system, using water, for example, can be integrated into the heat sink. During use, the high power beam is initially directed onto a start-stop target and after reaching its full power is translated around the slit disk assembly, wherein the beam enters the radial slits and the conducting disk radial slits and is detected at the Faraday cup assembly. A trigger probe assembly can also be integrated into the system in order to aid in the determination of the proper orientation of the beam during reconstruction. After passing over each of the slits, the beam is then rapidly translated back to the start-stop target to minimize the amount of time that the high power beam comes in contact with the slit disk assembly. The data obtained by the system is then transferred into a computer system, where a computer tomography algorithm is used to reconstruct the power density distribution of the beam.

  15. Thermal equilibrium of a cryogenic magnetized pure electron plasma

    NASA Technical Reports Server (NTRS)

    Dubin, D. H. E.; Oneil, T. M.

    1986-01-01

    The thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP). The N-particle spatial distribution rho sub s and the Helmholtz free energy F are evaluated for the McPEP to O(lambda sub d-squared/a-squared), where lambda sub d is the thermal de Broglie wavelength and is an interparticle spacing. The electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical. The distribution rho sub s is shown to be identical to that of a classical OCP with a slightly modified potential. To O(lambda sub d-squared/a-squared) this modification does not affect that part of F that is caused by correlations, as long as certain requirements concerning the size of the plasma are met. This theory is motivated by a current series of experiments that involve the cooling of a magnetically confined pure electron plasma to the cryogenic temperature range.

  16. Gamma Putty dosimetric studies in electron beam

    PubMed Central

    Gloi, Aime M.

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12–20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6–9 MeV). PMID:27651563

  17. RHIC electron lens beam transport system design considerations

    SciTech Connect

    Luo, Y.; Heimerle, M.; Fischer, W.; Pikin, A.; Beebe, E.; Bruno, D.; Gassner, D.; Gu, X.; Gupta, R. C.; Hock, J.; Jain, A.; Lambiase, R.; Mapes, M.; Meng, W.; Montag, C.; Oerter, B.; Okamura, M.; Raparia, D.; Tan, Y.; Than, R.; Tuozzolo, J.; Zhang, W.

    2010-08-03

    To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP6 and IP8. Each electron lens has several sub-systems, including electron gun, electron collector, superconducting main solenoid (SM), diagnostics system and power supply system. In addition to these systems, beam transport system which can transport electron beam from electron gun side to collector side is also needed.

  18. Current limiting mechanisms in electron and ion beam experiments

    NASA Technical Reports Server (NTRS)

    Olsen, R. C.

    1990-01-01

    The emission and collection of current from satellites or rockets in the ionosphere is a process which, at equilibrium, requires a balance between inward and outward currents. In most active experiments in the ionosphere and magnetosphere, the emitted current exceeds the integrated thermal current by one or more orders of magnitude. The system response is typically for the emitted current to be limited by processes such as differential charging of insulating surfaces, interactions between an emitted beam and the local plasma, and interactions between the beam and local neutral gas. These current limiting mechanisms have been illustrated for 20 years in sounding rocket and satellite experiments, which are reviewed here. Detailed presentations of the Spacecraft Charging at High Altitude (SCATHA) electron and ion gun experiments are used to demonstrate the general range of observed phenomena.

  19. Near equilibrium distributions for beams with space charge in linear and nonlinear periodic focusing systems

    SciTech Connect

    Sonnad, Kiran G.; Cary, John R.

    2015-04-15

    A procedure to obtain a near equilibrium phase space distribution function has been derived for beams with space charge effects in a generalized periodic focusing transport channel. The method utilizes the Lie transform perturbation theory to canonically transform to slowly oscillating phase space coordinates. The procedure results in transforming the periodic focusing system to a constant focusing one, where equilibrium distributions can be found. Transforming back to the original phase space coordinates yields an equilibrium distribution function corresponding to a constant focusing system along with perturbations resulting from the periodicity in the focusing. Examples used here include linear and nonlinear alternating gradient focusing systems. It is shown that the nonlinear focusing components can be chosen such that the system is close to integrability. The equilibrium distribution functions are numerically calculated, and their properties associated with the corresponding focusing system are discussed.

  20. Electron gun jitter effects on beam bunching

    SciTech Connect

    Liu, M. S.; Iqbal, M.

    2014-02-15

    For routine operation of Beijing Electron Positron Collider II (BEPCII) linac, many factors may affect the beam bunching process directly or indirectly. We present the measurements and analyses of the gun timing jitter, gun high voltage jitter, and beam energy at the exit of the standard acceleration section of the linac quantitatively. Almost 80 mV and more than 200 ps of gun high voltage and time jitters have ever been measured, respectively. It was analyzed that the gun timing jitter produced severe effects on beam energy than the gun high voltage jitter, if the timing jitter exceeded 100 ps which eventually deteriorates both the beam performance and the injection rate to the storage ring.

  1. Precision fast kickers for kiloampere electron beams

    SciTech Connect

    Caporaso, G.J.; Chen, Y.J.; Weir, J.T.

    1999-10-06

    These kickers will be used to make fast dipoles and quadrupoles which are driven by sharp risetime pulsers to provide precision beam manipulations for high current kA electron beams. This technology will be used on the 2nd axis of the DARHT linac at LANL. It will be used to provide 4 micropulses of pulse width 20 to 120 nsec. selected from a 2 {micro}sec., 2kA, 20MeV macropulse. The fast pulsers will have amplitude modulation capability to compensate for beam-induced steering effects and other slow beam centroid motion to within the bandwidth of the kicker system. Scaling laws derived from theory will be presented along with extensive experimental data obtained on the test bed ETA-II.

  2. Young's Interference Experiment with Electron Beams Carrying Orbital Angular Momentum

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yuya; Saitoh, Koh; Tanaka, Nobuo; Tanimura, Shogo; Uchida, Masaya

    2013-03-01

    A Young's-type double-slit experiment using electron beams carrying orbital angular momentum (OAM) is demonstrated in a transmission electron microscope. Each of the slits is replaced by a grating mask with a fork dislocation, which generates electron beams with OAM as diffracted beams. Interference fringes produced by two diffracted electron beams with OAM appear at the observation screen. The interference fringe patterns exhibit dislocation features depending on the topological charges of the two electron beams. The experimental results clearly show the wave nature of the electron beams with OAM and gives potential applications in electron physics and quantum mechanics.

  3. Auroral electron beams near the magnetic equator

    NASA Technical Reports Server (NTRS)

    Mcilwain, C. E.

    1975-01-01

    Intense beams of electrons traveling parallel to the local magnetic field have been observed at a magnetic latitude of 11 deg and a radial distance of 6.6 earth radii. The distribution function for electrons traveling within 8 deg of the field line direction is typically flat or slightly rising up to a break point beyond which it decreases as inversely as the 5-10th power of v. The energy corresponding to the break point velocity is usually between 0.1 and 10 keV. These beams are found to occur on closed field lines at the inner edge of the plasma sheet and thus at the root of the earth's magnetotail. Beams with break point energies greater than 2 keV seem to occur only within the first 10 minutes after the onset of hot plasma injection associated with a magnetospheric substorm.

  4. Longitudinal Diagnostics for Short Electron Beam Bunches

    SciTech Connect

    Loos, H.; /SLAC

    2010-06-11

    Single-pass free electron lasers require high peak currents from ultra-short electron bunches to reach saturation and an accurate measurement of bunch length and longitudinal bunch profile is necessary to control the bunch compression process from low to high beam energy. The various state-of-the-art diagnostics methods from ps to fs time scales using coherent radiation detection, RF deflection, and other techniques are presented. The use of linear accelerators as drivers for free electron lasers (FEL) and the advent of single-pass (SASE) FELs has driven the development of a wide range of diagnostic techniques for measuring the length and longitudinal distribution of short and ultra-short electron bunches. For SASE FELs the radiation power and the length of the undulator needed to achieve saturation depend strongly on the charge density of the electron beam. In the case of X-ray FELs, this requires the accelerator to produce ultra-high brightness beams with micron size transverse normalized emittances and peak currents of several kA through several stages of magnetic bunch compression. Different longitudinal diagnostics are employed to measure the peak current and bunch profile along these stages. The measurement techniques can be distinguished into different classes. Coherent methods detect the light emitted from the beam by some coherent radiation process (spectroscopic measurement), or directly measure the Coulomb field traveling with the beam (electro-optic). Phase space manipulation techniques map the time coordinate onto a transverse dimension and then use conventional transverse beam diagnostics (transverse deflector, rf zero-phasing). Further methods measure the profile or duration of an incoherent light pulse emitted by the bunch at wavelengths much shorted than the bunch length (streak camera, fluctuation technique) or modulate the electron beam at an optical wavelength and then generate a narrow bandwidth radiation pulse with the longitudinal profile of

  5. SLC polarized beam source electron optics design

    SciTech Connect

    Eppley, K.R.; Lavine, T.L.; Early, R.A.; Herrmannsfeldt, W.B.; Miller, R.H.; Schultz, D.C.; Spencer, C.M.; Yeremian, A.D.

    1991-05-01

    This paper describes the design of the beam-line from the polarized electron gun to the linac injector in the Stanford Linear Collider (SLC). The polarized electron source is a GaAs photocathode, requiring 10{sup {minus}11}-Torr-range pressure for adequate quantum efficiency and longevity. The photocathode is illuminated by 3-nsec-long laser pulses. The quality of the optics for the 160-kV beam is crucial since electron-stimulated gas desorption from beam loss in excess of 0.1% of the 20-nC pulses may poison the photocathode. Our design for the transport line consists of a differential pumping region isolated by a pair of valves. Focusing is provided by a pair of Helmholtz coils and by several iron-encased solenoidal lenses. Our optics design is based on beam transport simulations using 2{1/2}-D particle-in-cell codes to model the gun and to solve the fully-relativistic time-dependent equations of motion in three dimensions for electrons in the presence of azimuthally symmetric electromagnetic fields. 6 refs., 6 figs.

  6. Electron Beam Applications in Chemical Processing

    NASA Astrophysics Data System (ADS)

    Martin, D.; Dragusin, M.; Radoiu, M.; Moraru, R.; Oproiu, C.; Cojocaru, G.; Margarit, C.

    1997-05-01

    Our recent results in the field of polymeric materials obtained by electron beam irradiation are presented. Two types of polymeric flocculants and three hydrogels are described. The effects of radiation absorbed dose and chemical composition of the irradiated solutions upon the polymeric materials characteristics are discussed. The required absorbed dose levels to produce the polymeric flocculants are in the range of 0.4 kGy to 1 kGy, and 4 kGy to 12 kGy for hydrogels. Experimental results obtained by testing polymeric flocculants with waste water from food industry are given. Plymeric materials processing was developed on a pilot small scale level with a 0.7 kW and 5.5 MeV linac built in Romania. A new facility for application of combined electron beam and microwave irradiation in the field of polymeric materials preparation is presently under investigation. Preliminary results have demonstrated that some polymeric flocculants characteristics, such as linearity, were improved by using combined electron beam and microwave irradiation. Also, the absorbed dose levels decreases in comparison with those required when only electron beam irradiation was used.

  7. Dielectric charging by an electron beam

    NASA Astrophysics Data System (ADS)

    Upatov, V. Y.

    1996-08-01

    Experimental discovery of a charge spot field effect (CSFE) has altered considerably our understanding of dielectric charging by an electron beam, under conditions typical for the operation of a large class of cathode ray tubes (CRT). Dielectric charging by an electron beam was studied using a specific pulse method for the measurement of the potential. The accuracy of this method is discussed. Measurements were made of the potential relief of a positively charged spot on muscovite mica (quartz, aluminum oxide). The potential at the spot center, under conditions described in the paper and at a relatively long charging time, was shown to be considerably lower than that of the collector. Potential dependence on charging time, determined under the same conditions, is shown for the charged spot center and a number of adjacent points. During creation of the charged spot charging current was measured. The results of the measurements are discussed. A new mechanism of dielectric charging by electron beam is proposed. A CSFE is formulated, and its significance for the operation of CRT is stated. Criticism is given of in-plane grid effect. The paper presents calculations of fields for grid target models determining the mechanism of dielectric charging by electron beam.

  8. The CMS Beam Halo Monitor electronics

    NASA Astrophysics Data System (ADS)

    Tosi, N.; Dabrowski, A. E.; Fabbri, F.; Grassi, T.; Hughes, E.; Mans, J.; Montanari, A.; Orfanelli, S.; Rusack, R.; Torromeo, G.; Stickland, D. P.; Stifter, K.

    2016-02-01

    The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes (PMTs). The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few nanosecond resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is read out via IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providing online feedback on the beam quality. A dedicated calibration monitoring system has been designed to generate short triggered pulses of light to monitor the efficiency of the system. The electronics has been in operation since the first LHC beams of Run II and has served as the first demonstration of the new QIE10, Microsemi Igloo2 FPGA and high-speed 5 Gbps link with LHC data.

  9. Electron lenses for head-on beam-beam compensation in RHIC

    NASA Astrophysics Data System (ADS)

    Gu, X.; Fischer, W.; Altinbas, Z.; Anerella, M.; Bajon, E.; Bannon, M.; Bruno, D.; Costanzo, M.; Drees, A.; Gassner, D. M.; Gupta, R. C.; Hock, J.; Harvey, M.; Jain, A. K.; Jamilkowski, J. P.; Kankiya, P.; Lambiase, R.; Liu, C.; Luo, Y.; Mapes, M.; Marusic, A.; Mi, C.; Michnoff, R.; Miller, T. A.; Minty, M.; Nemesure, S.; Ng, W.; Phillips, D.; Pikin, A. I.; Rosas, P. J.; Robert-Demolaize, G.; Samms, T.; Sandberg, J.; Schoefer, V.; Shrey, T. C.; Tan, Y.; Than, R.; Theisen, C.; Thieberger, P.; Tuozzolo, J.; Wanderer, P.; Zhang, W.; White, S. M.

    2017-02-01

    Two electron lenses (e -lenses) have been in operation during the 2015 RHIC physics run as part of a head-on beam-beam compensation scheme. While the RHIC lattice was chosen to reduce the beam-beam-induced resonance-driving terms, the electron lenses reduced the beam-beam-induced tune spread. This has been demonstrated for the first time. The beam-beam compensation scheme allows for higher beam-beam parameters and therefore higher intensities and luminosity. In this paper, we detail the design considerations and verification of the electron beam parameters of the RHIC e -lenses. Longitudinal and transverse alignments with ion beams and the transverse beam transfer function measurement with head-on electron-proton beam are presented.

  10. An electron optical theory of beam blanking

    NASA Astrophysics Data System (ADS)

    Gesley, M.

    1993-11-01

    Trajectory equations are derived in closed form for electrons in time-dependent electric fields produced by beam blankers. Simple parallel plate and double-deflection blankers with transmission delay lines are evaluated. Lens imaging of the apparent beam motion is analyzed by developing the virtual electron trajectories obtained from linear extrapolation back into the blanker region. Lens excitation effects and conjugate blanking optics can then be described. The blanker voltage is represented by a damped exponential cosine term, which satisfies a typical circuit equation for the driver-amplifier. The form of the trajectory equation is written as a 3×3 matrix, which comprises a set of conditional solutions that are determined by blanker geometry. The optimum delay line length of any double-deflection blanker can then be determined. The blanker-induced beam jitter is shown to be significantly reduced by using this configuration. The effect of the blanker beam stop on the motion at the target plane is given by combining results on the real and apparent beam trajectories.

  11. New shielding materials for clinical electron beams.

    PubMed

    Tajiri, Minoru; Tokiya, Yuji; Uenishi, Jun; Sunaoka, Masayoshi; Watanabe, Kazuhiro

    2006-09-01

    Since lead has recently been recognized as a source of environmental pollution, we have investigated new electron shielding materials that do not contain lead. We compared the shielding thicknesses of a hard plate and a sheet composed of the new materials with that of lead for electron beams. The shielding thickness was evaluated as the thickness required for shielding primary electrons. The comparison revealed the shielding ability of the hard plate and sheet is approximately equivalent to 1.0 and 0.9 times that of lead, respectively. The thickness (in millimeters) required for shielding by the hard-plate, as well as the thickness of lead, is related to approximately half of the electron-beam energy (in MeV). The shielding ability of the sheet is also equivalent to that of Lipowitz alloy. Moreover these materials are environmentally friendly, and can be easily customized into arbitrary shapes. Therefore they can be used as lead substitutes for shielding against electron beams.

  12. MULTIPLE ELECTRON BEAM ION PUMP AND SOURCE

    DOEpatents

    Ellis, R.E.

    1962-02-27

    A vacuum pump is designed which operates by ionizing incoming air and by withdrawing the ions from the system by means of electrical fields. The apparatus comprises a cylindrical housing communicable with the vessel to be evacuated and having a thin wall section in one end. Suitable coils provide a longitudinal magnetic field within the cylinder. A broad cathode and an anode structure is provided to establish a plurality of adjacent electron beams which are parallel to the cylinder axis. Electron reflector means are provided so that each of the beams constitutes a PIG or reflex discharge. Such structure provides a large region in which incoming gas molecules may be ionized by electron bombardment. A charged electrode assembly accelerates the ions through the thin window, thereby removing the gas from the system. The invention may also be utilized as a highly efficient ion source. (AEC)

  13. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

    SciTech Connect

    Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G.; Singh, P.

    2013-12-15

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  14. Instrumental Asymmetry Reduction in Polarized Electron Beams

    NASA Astrophysics Data System (ADS)

    Fabrikant, M. I.; Trantham, K. W.; Gay, T. J.

    2008-05-01

    We report progress in the reduction of instrumental asymmetries (IAs) related to the photoemission of polarized electrons from GaAs caused by circularly-polarized diode laser beams [1]. Such asymmetries can mask true helicity-dependent interactions between the emitted electrons and chiral targets. Minimization of laser intensity IAs is achieved by chopping two spatially separated light beams with orthogonal polarizations which are recombined and passed through a quarter-wave plate to yield a single beam with rapidly flipping helicity. We have demonstrated the ability to reduce intensity IAs of the laser beam itself to less than 2 x 10-6 [2]. We have also investigated the IAs of the photemission current from the GaAs. At present, we are able to reduce the photoemission asymmetry to values that are comparable to the laser intensity asymmetry. Implications for experiments measuring effects due to electron circular dichroism [3] will be discussed. [1]Trantham K.W. et al J. Phys. B. 28 L543 (1995) [2] Fabrikant M.I. et al submitted to Appl. Opt. [3] Mayer S., Kessler J. Phys. Rev. Lett. 74, 4803 (1995) Funding for this project was provided by Undergraduate Creative Activities and Research Experiences (UCARE) and the National Science Foundation (PHY-0653379).

  15. Measuring the Fluence of Clinical Electron Beams

    NASA Astrophysics Data System (ADS)

    Zaini, Mehran

    1995-01-01

    The incident electron fluence on the patient is greatly affected by the various collimator components on the path of the beam. It is therefore important to measure and characterize these fluence perturbations, which alter the dose distributions. In addition, the incident fluence information is needed as input for the treatment planning algorithms, which are presently inferred from the dose measurements. The magnitude of electron fluence for patient treatments is very low and it is difficult to assess directly. Therefore, a specially designed fluence-meter is required. Of all the detection methods, an ion-implanted semiconductor detector with an ultra-thin depletion layer is the most suitable. We have shown that the energy deposited in an ultra-thin detector, with no window, is directly proportional to the incident fluence of clinical electron beams, including the small contribution of delta-rays. The main reasons for this concept are that (L/rho ) of silicon is essentially constant over the spectrum of any clinical beam and these beams are almost mono-energetic. Our detector is calibrated against a flat Faraday cup and can provide a measure of true electron fluence, with almost no energy and directional dependence. Calibrations are done in a vacuum chamber, where the chamber and the measuring electronics are connected to the accelerator ground. In the calibration setup, a pipe collimation system is used to create a mono-directional beam, so that Phi = Phi_{planar }. Geometrical calculations and films are used for making quantitative analysis of the beam impinging on the detector and the cup. The precision of the calibrations is below 1%. Since the calibration factors of the detector are the same on two different linacs, once a detector is calibrated, it can measure electron fluence on any clinical machine. Fluence output and profiles, and dphi /dtheta of a variety of cones and blocks are measured. The measured surface fluence values conform to the expected shape of

  16. Polarized electron beams at milliampere average current

    SciTech Connect

    Poelker, Matthew

    2013-11-01

    This contribution describes some of the challenges associated with developing a polarized electron source capable of uninterrupted days-long operation at milliAmpere average beam current with polarization greater than 80%. Challenges will be presented in the context of assessing the required level of extrapolation beyond the performance of today's CEBAF polarized source operating at ~ 200 uA average current. Estimates of performance at higher current will be based on hours-long demonstrations at 1 and 4 mA. Particular attention will be paid to beam-related lifetime-limiting mechanisms, and strategies to construct a photogun that operate reliably at bias voltage > 350kV.

  17. Electron Accelerators for Radioactive Ion Beams

    SciTech Connect

    Lia Merminga

    2007-10-10

    The summary of this paper is that to optimize the design of an electron drive, one must: (a) specify carefully the user requirements--beam energy, beam power, duty factor, and longitudinal and transverse emittance; (b) evaluate different machine options including capital cost, 10-year operating cost and delivery time. The author is convinced elegant solutions are available with existing technology. There are several design options and technology choices. Decisions will depend on system optimization, in-house infrastructure and expertise (e.g. cryogenics, SRF, lasers), synergy with other programs.

  18. High Efficiency Transverse D. C. Electron Beams.

    DTIC Science & Technology

    1984-10-01

    cathode er pressures is also possible, however, the electron beam be- materials. For example, copper beryllium has a high secon- comes poorly collimated as...50-50% by weight 0.6 acceptable Molybdenum-MgO 6. Graphite 0.1 low 7. Copper 0.05 very high .1 8. Copper- beryllium 98-2% 0.05 very high 9. Stainless...reached 10% of the initial value at a total energy of BEAM S HEET 725 J/cm2. Annealing of doped polysilicon and silicide films was also achieved. Fig

  19. Guided Radiation Beams in Free Electron Lasers.

    DTIC Science & Technology

    1988-05-19

    the electron beam in an FEL that the radiation beam will remain guided. 0 20 II. Refractive Index Associated with FELs In our model, the vector ...eIAw/ymOc(exp(ikwz) + c.c.) ex/2 , is the wiggle velocity, y is the Lorentz factor, Aw is the vector potential amplitude of the planar wiggler...Balboa Avenue Palo Alto, CA 94303 San Diego, CA 92123 38 Dr. S. Krinsky Nat. Synchrotron Light Source Dr. Michael Lavan Brookhaven National Laboratory U.S

  20. Surface waves of high amplitude excited by relativistic electron beam on plasma boundary

    NASA Astrophysics Data System (ADS)

    Bogdanova, S. N.; Reshetnikova, K. A.; Dankov, P. I.; Ivanov, S. T.

    1984-06-01

    The equilibrium state of a relativistic electron beam and a surface EM-wave of large amplitude on the beam-plasma boundary is analysed in hydrodynamic approximation. Taking into consideration the law of conversion of energy, the phase velocity, the wave amplitude, the efficiency of transformation of the kinetic energy into the energy of electromagnetic field and the distribution of the energy of a beam transferred to a system have been obtained. This energy is expended both on excitation of a surface wave and on plasma electrons oscillations.

  1. Beam Dynamics Considerations in Electron Ion Colliders

    NASA Astrophysics Data System (ADS)

    Krafft, Geoffrey

    2015-04-01

    The nuclear physics community is converging on the idea that the next large project after FRIB should be an electron-ion collider. Both Brookhaven National Lab and Thomas Jefferson National Accelerator Facility have developed accelerator designs, both of which need novel solutions to accelerator physics problems. In this talk we discuss some of the problems that must be solved and their solutions. Examples in novel beam optics systems, beam cooling, and beam polarization control will be presented. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

  2. Electron beam throughput from raster to imaging

    NASA Astrophysics Data System (ADS)

    Zywno, Marek

    2016-12-01

    Two architectures of electron beam tools are presented: single beam MEBES Exara designed and built by Etec Systems for mask writing, and the Reflected E-Beam Lithography tool (REBL), designed and built by KLA-Tencor under a DARPA Agreement No. HR0011-07-9-0007. Both tools have implemented technologies not used before to achieve their goals. The MEBES X, renamed Exara for marketing purposes, used an air bearing stage running in vacuum to achieve smooth continuous scanning. The REBL used 2 dimensional imaging to distribute charge to a 4k pixel swath to achieve writing times on the order of 1 wafer per hour, scalable to throughput approaching optical projection tools. Three stage architectures were designed for continuous scanning of wafers: linear maglev, rotary maglev, and dual linear maglev.

  3. Simulation tools for pinched-electron-beam radiographic diodes

    NASA Astrophysics Data System (ADS)

    Humphries, Stanley; Orzechowski, Thaddeus

    2006-02-01

    We describe capabilities of an integrated software suite to simulate pinched-electron-beam diodes for pulsed radiography. In contrast to other reported work using particle-in-cell methods, we employ a ray-tracing code (Trak) with advanced capabilities for modeling beam-generated magnetic fields. Ray tracing is a direct approach to a steady-state solution and involves less work than a particle-in-cell calculation. The second software component, GamBet, is a new Monte Carlo code for radiation transport that incorporates effects of the complex electric and magnetic fields at the radiation target. The ray-tracing approach exhibits good convergence in calculations for the diode geometry of the compact radiography (CRAD) program at Lawrence Livermore National Laboratory. With a 1.5 MV, 30 ns driver, we predict that the diode can produce a beam with axial length ˜1 mm that generates isotropic bremsstrahlung radiation exceeding 1 rad at 1 m. The ray-tracing procedure encounters convergence problems when applied to the rod-pinch geometry, a configuration used in several pulsed radiographic machines. We observe a fundamental difference in the nature of electron orbits in the two diodes. There is an increased chance for particle-orbit feedback in the rod pinch, so that equilibrium solutions are sensitive to small changes in emission characteristics.

  4. Disabling CNT Electronic Devices by Use of Electron Beams

    NASA Technical Reports Server (NTRS)

    Petkov, Mihail

    2008-01-01

    Bombardment with tightly focused electron beams has been suggested as a means of electrically disabling selected individual carbon-nanotubes (CNTs) in electronic devices. Evidence in support of the suggestion was obtained in an experiment in which a CNT field-effect transistor was disabled (see figure) by focusing a 1-keV electron beam on a CNT that served as the active channel of a field-effect transistor (FET). Such bombardment could be useful in the manufacture of nonvolatile-memory circuits containing CNT FETs. Ultimately, in order to obtain the best electronic performances in CNT FETs and other electronic devices, it will be necessary to fabricate the devices such that each one contains only a single CNT as an active element. At present, this is difficult because there is no way to grow a single CNT at a specific location and with a specific orientation. Instead, the common practice is to build CNTs into electronic devices by relying on spatial distribution to bridge contacts. This practice results in some devices containing no CNTs and some devices containing more than one CNT. Thus, CNT FETs have statistically distributed electronic characteristics (including switching voltages, gains, and mixtures of metallic and semiconducting CNTs). According to the suggestion, by using a 1-keV electron beam (e.g., a beam from a scanning electron microscope), a particular nanotube could be rendered electrically dysfunctional. This procedure could be repeated as many times as necessary on different CNTs in a device until all of the excess CNTs in the device had been disabled, leaving only one CNT as an active element (e.g., as FET channel). The physical mechanism through which a CNT becomes electrically disabled is not yet understood. On one hand, data in the literature show that electron kinetic energy >86 keV is needed to cause displacement damage in a CNT. On the other hand, inasmuch as a 1-keV beam focused on a small spot (typically a few tens of nanometers wide

  5. Compact two-beam push-pull free electron laser

    DOEpatents

    Hutton, Andrew

    2009-03-03

    An ultra-compact free electron laser comprising a pair of opposed superconducting cavities that produce identical electron beams moving in opposite directions such that each set of superconducting cavities accelerates one electron beam and decelerates the other electron beam. Such an arrangement, allows the energy used to accelerate one beam to be recovered and used again to accelerate the second beam, thus, each electron beam is decelerated by a different structure than that which accelerated it so that energy exchange rather than recovery is achieved resulting in a more compact and highly efficient apparatus.

  6. Experimental Studies of Compensation of Beam-Beam Effects with Tevatron Electron Lenses

    SciTech Connect

    Shiltsev, V.; Alexahin, Yu.; Bishofberger, Kip; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.; /Fermilab /Los Alamos /Novosibirsk, IYF /CERN

    2008-02-01

    Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with 'electron lenses', novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.

  7. Electron Beam Welding of Gear Wheels by Splitted Beam

    NASA Astrophysics Data System (ADS)

    Dřímal, Daniel

    2014-06-01

    This contribution deals with the issue of electron beam welding of high-accurate gear wheels composed of a spur gearing and fluted shaft joined with a face weld for automotive industry. Both parts made of the high-strength low-alloy steel are welded in the condition after final machining and heat treatment, performed by case hardening, whereas it is required that the run-out in the critical point of weldment after welding, i. e. after the final operation, would be 0.04 mm max.. In case of common welding procedure, cracks were formed in the weld, initiated by spiking in the weld root. Crack formation was prevented by the use of an interlocking joint with a rounded recess and suitable welding parameters, eliminating crack initiation by spiking in the weld root. Minimisation of the welding distortions was achieved by the application of tack welding with simultaneous splitting of one beam into two parts in the opposite sections of circumferential face weld attained on the principle of a new system of controlled deflection with digital scanning of the beam. This welding procedure assured that the weldment temperature after welding would not be higher than 400 °C. Thus, this procedure allowed achieving the final run-outs in the critical point of gearwheels within the maximum range up to 0.04 mm, which is acceptable for the given application. Accurate optical measurements did not reveal any changes in the teeth dimensions.

  8. Electron-beam distillation of natural polymers

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. V.; Makarov, I. E.; Ershov, B. G.

    2014-01-01

    Pyrolysis of cellulose, lignin, and chitin may be upgraded by the use of an electron-beam irradiation. The radiation-thermal destruction mode does more probable production of liquid low-molecular-weight products instead of solid pyrolitic oligomers. Furans, methoxyphenols, and pyridines are dominant products of high-temperature radiolysis of cellulose, lignin, and chitin, respectively. The mechanism of chain destruction of natural polymers is considered.

  9. Susceptor heating device for electron beam brazing

    DOEpatents

    Antieau, Susan M.; Johnson, Robert G. R.

    1999-01-01

    A brazing device and method are provided which locally apply a controlled amount of heat to a selected area, within a vacuum. The device brazes two components together with a brazing metal. A susceptor plate is placed in thermal contact with one of the components. A serrated pedestal supports the susceptor plate. When the pedestal and susceptor plate are in place, an electron gun irradiates an electron beam at the susceptor plate such that the susceptor plate is sufficiently heated to transfer heat through the one component and melt the brazing metal.

  10. Beam-beam and electron cloud effects in CEPC/FCC-ee

    NASA Astrophysics Data System (ADS)

    Ohmi, Kazuhito

    2016-11-01

    We discuss beam dynamics issues in CEPC/FCC-ee, especially focusing on the beam-beam and electron cloud effects. Beamstrahlung is strong in extreme high energy collision such as Higgs and top factory. Beam-beam simulations considering beamstrahlung are now ready. Several points of beam-beam effects for FCC-ee are presented. Electron cloud effects are serious for high current positron machine, especially in Z factory that many bunches are stored. Analytical estimate for threshold of electron density and electron build-up for CEPC are presented.

  11. Recent Experience with Electron Lens Beam-Beam Compensation at the Tevatron

    SciTech Connect

    Kuznetsov, G.; Saewert, G.; Shiltsev, V.; Valishev, A.; Kamerdzhiev, V.; /Julich, Forschungszentrum

    2009-05-01

    Tevatron Electron Lenses (TEL) have reliably demonstrated correction of the bunch-to-bunch tune shift induced by long-range beam-beam interactions. With the commissioning of the new high voltage modulator that became operational in 2008, the electron beam can be pulsed on every bunch of the Tevatron beam. We report on the recent results of beam-beam compensation studies in the high luminosity regime.

  12. Electron beam coupling to a metamaterial structure

    SciTech Connect

    French, David M.; Shiffler, Don; Cartwright, Keith

    2013-08-15

    Microwave metamaterials have shown promise in numerous applications, ranging from strip lines and antennas to metamaterial-based electron beam driven devices. In general, metamaterials allow microwave designers to obtain electromagnetic characteristics not typically available in nature. High Power Microwave (HPM) sources have in the past drawn inspiration from work done in the conventional microwave source community. In this article, the use of metamaterials in an HPM application is considered by using an effective medium model to determine the coupling of an electron beam to a metamaterial structure in a geometry similar to that of a dielectric Cerenkov maser. Use of the effective medium model allows for the analysis of a wide range of parameter space, including the “mu-negative,”“epsilon-negative,” and “double negative” regimes of the metamaterial. The physics of such a system are modeled analytically and by utilizing the particle-in-cell code ICEPIC. For this geometry and effective medium representation, optimum coupling of the electron beam to the metamaterial, and thus the optimum microwave or RF production, occurs in the epsilon negative regime of the metamaterial. Given that HPM tubes have been proposed that utilize a metamaterial, this model provides a rapid method of characterizing a source geometry that can be used to quickly understand the basic physics of such an HPM device.

  13. Fast magnetospheric echoes of energetic electron beams

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

    1985-01-01

    Electron beam experiments using rocketborne instrumentation have confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. A total of 234 echoes have been observed in a pitch angle range from 9 to 110 deg at energies of 1.87 and 3.90 keV. Out of this number, 95 echoes could unambiguously be identified with known accelerator operations at 2-, 4-, or 8-keV energy and highest current levels resulting in the determination of transit times of typically 300 to 400 ms. In most cases, when echoes were present in both energy channels, the higher-energy electrons led the lower-energy ones by 50 to 70 ms. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. An alternative interpretation is briefly examined, and its relative merit in describing the observations is evaluated. The injection process is discussed in some detail as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection for both processes.

  14. Transverse profile imager for ultrabright electron beams

    NASA Astrophysics Data System (ADS)

    Ischebeck, Rasmus; Prat, Eduard; Thominet, Vincent; Ozkan Loch, Cigdem

    2015-08-01

    A transverse profile imager for ultrabright electron beams is presented, which overcomes resolution issues in present designs by observing the Scheimpflug imaging condition as well as the Snell-Descartes law of refraction in the scintillating crystal. Coherent optical transition radiation emitted by highly compressed electron bunches on the surface of the crystal is directed away from the camera, allowing to use the monitor for profile measurements of electron bunches suitable for X-ray free electron lasers. The optical design has been verified by ray tracing simulations, and the angular dependency of the resolution has been verified experimentally. An instrument according to the presented design principles has been used in the SwissFEL Injector Test Facility, and different scintillator materials have been tested. Measurements in conjunction with a transverse deflecting radiofrequency structure and an array of quadrupole magnets demonstrate a normalized slice emittance of 25 nm in the core of a 30 fC electron beam at a pulse length of 10 ps and a particle energy of 230 MeV.

  15. Optimizing the beam-beam alignment in an electron lens using bremsstrahlung

    SciTech Connect

    Montag, C.; Fischer, W.; Gassner, D.; Thieberger, P.; Haug, E.

    2010-05-23

    Installation of electron lenses for the purpose of head-on beam-beam compensation is foreseen at RHIC. To optimize the relative alignment of the electron lens beam with the circulating proton (or ion) beam, photon detectors will be installed to measure the bremsstrahlung generated by momentum transfer from protons to electrons. We present the detector layout and simulations of the bremsstrahlung signal as function of beam offset and crossing angle.

  16. Emittance growth of an nonequilibrium intense electron beam in a transport channel with discrete focusing

    SciTech Connect

    Carlsten, B.E.

    1997-02-01

    The author analyzes the emittance growth mechanisms for a continuous, intense electron beam in a focusing transport channel, over distances short enough that the beam does not reach equilibrium. The emittance grows from the effect of nonlinear forces arising from (1) current density nonuniformities, (2) energy variations leading to nonlinearities in the space-charge force even if the current density is uniform, (3) axial variations in the radial vector potential, (4) an axial velocity shear along the beam, and (5) an energy redistribution of the beam as the beam compresses or expands. The emittance growth is studied analytically and numerically for the cases of balanced flow, tight focusing, and slight beam scalloping, and is additionally studied numerically for an existing 6-MeV induction linear accelerator. Rules for minimizing the emittance along a beamline are established. Some emittance growth will always occur, both from current density nonuniformities that arise along the transport and from beam radius changes along the transport.

  17. RHIC electron lens beam transport system design considerations

    SciTech Connect

    Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Jain, A.; Raparia, D.

    2010-10-01

    To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP10. Electron beam transport system is one of important subsystem, which is used to transport electron beam from electron gun side to collector side. This system should be able to change beam size inside superconducting magnet and control beam position with 5 mm in horizontal and vertical plane. Some other design considerations for this beam transport system are also reported in this paper. The head-on beam-beam effect is one of important nonlinear source in storage ring and linear colliders, which have limited the luminosity improvement of many colliders, such as SppS, Tevatron and RHIC. In order to enhance the performance of colliders, beam-beam effects can be compensated with direct space charge compensation, indirect space charge compensation or betatron phase cancellation scheme. Like other colliders, indirect space charge compensation scheme (Electron Lens) was also proposed for Relativistic Heavy Ion Collider (RHIC) beam-beam compensation at Brookhaven National Laboratory. The two similar electron lenses are located in IR10 between the DX magnets. One RHIC electron lens consists of one DC electron gun, one superconducting magnet, one electron collector and beam transport system.

  18. First test of BNL electron beam ion source with high current density electron beam

    SciTech Connect

    Pikin, Alexander Alessi, James G. Beebe, Edward N.; Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard

    2015-01-09

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm{sup 2} and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio < 4.5 are requested by many heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  19. First test of BNL electron beam ion source with high current density electron beam

    NASA Astrophysics Data System (ADS)

    Pikin, Alexander; Alessi, James G.; Beebe, Edward N.; Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard

    2015-01-01

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm2 and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio < 4.5 are requested by many heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  20. Use of beam deflection to control an electron beam wire deposition process

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M. (Inventor); Hofmeister, William H. (Inventor); Hafley, Robert A. (Inventor)

    2013-01-01

    A method for controlling an electron beam process wherein a wire is melted and deposited on a substrate as a molten pool comprises generating the electron beam with a complex raster pattern, and directing the beam onto an outer surface of the wire to thereby control a location of the wire with respect to the molten pool. Directing the beam selectively heats the outer surface of the wire and maintains the position of the wire with respect to the molten pool. An apparatus for controlling an electron beam process includes a beam gun adapted for generating the electron beam, and a controller adapted for providing the electron beam with a complex raster pattern and for directing the electron beam onto an outer surface of the wire to control a location of the wire with respect to the molten pool.

  1. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    SciTech Connect

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  2. Theory of Electron Beam Moiré

    PubMed Central

    Read, David T.; Dally, James W.

    1996-01-01

    When a specimen surface carrying a high-frequency line grating is examined under a scanning electron microscope (SEM), moiré fringes are observed at several different magnifications. The fringes are characterized by their spatial frequency, orientation, and contrast. These features of the moiré pattern depend on the spatial frequency mismatch between the specimen grating and the raster scan lines, the diameter of the electron beam, and the detailed topography of the lines on the specimen. A mathematical model of e-beam moiré is developed that expresses the spatial dependence of the SEM image brightness as a product of the local intensity of the scanning beam and the local scattering function from the specimen grating. Equations are derived that give the spatial frequency of the moiré fringes as functions of the microscope settings and the spatial frequency of the specimen grating. The model also describes the contrast of several different types of moiré fringes that are observed at different magnifications. We analyze the formation of these different fringe patterns, and divide them into different categories including natural fringes, fringes of multiplication, fringes of division, and fringes of rotation. PMID:27805092

  3. Prediction of electron beam output factors.

    PubMed

    Mills, M D; Hogstrom, K R; Almond, P R

    1982-01-01

    A method to predict square and rectangular field output factors from the measurement of selected fields of electron beams on the Therac 20 Saturne has been developed. A two parameter fit of the square field output factor data, based on the functional dependence as predicted by a pencil beam calculational model, has proven clinically acceptable. The pencil beam distributions are given by the Fermi-Eyges theory of multiple Coulomb scattering. For a rectangular field, the output factor can be calculated from the square root of the product of the two square field output factors wtih sides equal to those of the rectangular field. If however, there is a significant asymmetry between the X and Y collimator systems, then rectangular field output factors should be predicted from the product of the X and Y one-dimensional output factors. One-dimensional output factors are defined as output factors of rectangular fields where one side remains constant and equal to the side of the square reference field. Measured data indicate either of the two methods of determining rectangular field output factors to be clinically acceptable for the Therac 20, the use of one-dimensional output factors demonstrating greater accuracy. Data show agreement to within approximately 1.5% at electron energies of 6, 9, 13, and 17 MeV.

  4. Electron vortex beams with high quanta of orbital angular momentum.

    PubMed

    McMorran, Benjamin J; Agrawal, Amit; Anderson, Ian M; Herzing, Andrew A; Lezec, Henri J; McClelland, Jabez J; Unguris, John

    2011-01-14

    Electron beams with helical wavefronts carrying orbital angular momentum are expected to provide new capabilities for electron microscopy and other applications. We used nanofabricated diffraction holograms in an electron microscope to produce multiple electron vortex beams with well-defined topological charge. Beams carrying quantized amounts of orbital angular momentum (up to 100ħ) per electron were observed. We describe how the electrons can exhibit such orbital motion in free space in the absence of any confining potential or external field, and discuss how these beams can be applied to improved electron microscopy of magnetic and biological specimens.

  5. Designing a beam transport system for RHIC's electron lens

    SciTech Connect

    Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Raparia, D.

    2011-03-28

    We designed two electron lenses to apply head-on beam-beam compensation for RHIC; they will be installed near IP10. The electron-beam transport system is an important subsystem of the entire electron-lens system. Electrons are transported from the electron gun to the main solenoid and further to the collector. The system must allow for changes of the electron beam size inside the superconducting magnet, and for changes of the electron position by 5 mm in the horizontal- and vertical-planes.

  6. Electron beam directed energy device and methods of using same

    DOEpatents

    Retsky, Michael W.

    2007-10-16

    A method and apparatus is disclosed for an electron beam directed energy device. The device consists of an electron gun with one or more electron beams. The device includes one or more accelerating plates with holes aligned for beam passage. The plates may be flat or preferably shaped to direct each electron beam to exit the electron gun at a predetermined orientation. In one preferred application, the device is located in outer space with individual beams that are directed to focus at a distant target to be used to impact and destroy missiles. The aimings of the separate beams are designed to overcome Coulomb repulsion. A method is also presented for directing the beams to a target considering the variable terrestrial magnetic field. In another preferred application, the electron beam is directed into the ground to produce a subsurface x-ray source to locate and/or destroy buried or otherwise hidden objects including explosive devices.

  7. Polarized electron beams at milliampere average current

    SciTech Connect

    Poelker, M.

    2013-11-07

    This contribution describes some of the challenges associated with developing a polarized electron source capable of uninterrupted days-long operation at milliAmpere average beam current with polarization greater than 80%. Challenges will be presented in the context of assessing the required level of extrapolation beyond the performance of today’s CEBAF polarized source operating at ∼ 200 uA average current. Estimates of performance at higher current will be based on hours-long demonstrations at 1 and 4 mA. Particular attention will be paid to beam-related lifetime-limiting mechanisms, and strategies to construct a photogun that operate reliably at bias voltage > 350kV.

  8. Beam conditioner for free electron lasers and synchrotrons

    DOEpatents

    Liu, H.; Neil, G.R.

    1998-09-08

    A focused optical has been used to introduce an optical pulse, or electromagnetic wave, collinear with the electron beam in a free electron laser or synchrotron thereby adding an axial field component that accelerates the electrons on the radial outside of the distribution of electrons in the electron beam. This invention consists of using the axial electrical component of a TEM{sub 10} mode Gaussian beam in vacuum to condition the electron beam and speed up the outer electrons in the beam. The conditioning beam should possess about the same diameter as the electron beam. The beam waist of the conditioning wave must be located around the entrance of the undulator longitudinally to have a net energy exchange between the electrons in the outer part of the distribution and the conditioning wave owing to the natural divergence of a Gaussian beam. By accelerating the outer electrons, the outer and core electrons are caused to stay in phase. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron. 4 figs.

  9. Beam conditioner for free electron lasers and synchrotrons

    DOEpatents

    Liu, Hongxiu; Neil, George R.

    1998-01-01

    A focused optical is been used to introduce an optical pulse, or electromagnetic wave, colinearly with the electron beam in a free electron laser or synchrotron thereby adding an axial field component that accelerates the electrons on the radial outside of the distribution of electrons in the electron beam. This invention consists of using the axial electrical component of a TEM.sub.10 mode Gaussian beam in vacuum to condition the electron beam and speed up the outer electrons in the beam. The conditioning beam should possess about the same diameter as the electron beam. The beam waist of the conditioning wave must be located around the entrance of the undulator longitudinally to have a net energy exchange between the electrons in the outer part of the distribution and the conditioning wave owing to the natural divergence of a Gaussian beam. By accelerating the outer electrons, the outer and core electrons are caused to stay in phase. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron.

  10. Intense Microsecond Electron Beam Interactions with Low-Pressure Gases

    DTIC Science & Technology

    1991-02-28

    Gilgenbach, J. E. Tucker, and C. L. Enloe, Laser and Particle Beams, 6 687 (1988). 4) "Undulation of a Magnetized Electron Beam by a Periodic Ion...Excitation by Relativistic Electrons: I. Collisions Cross Sections and Deposition Efficiencies", Laser and Particle Beams 8 493 (1990) 11) D.B...McGarrah and M.L. Brake, Argon Ion Excitation by Relativistic Electrons: II. Chemical Kinetics", Laser and Particle Beams 8 507 (1990) 9 T-PS/18/3//35709

  11. Purification of Niobium by Electron Beam Melting

    NASA Astrophysics Data System (ADS)

    Sankar, M.; Mirji, K. V.; Prasad, V. V. Satya; Baligidad, R. G.; Gokhale, A. A.

    2016-06-01

    Pure niobium metal, produced by alumino-thermic reduction of niobium oxide, contains various impurities which need to be reduced to acceptable levels to obtain aerospace grade purity. In the present work, an attempt has been made to refine niobium metals by electron beam drip melting technique to achieve purity confirming to the ASTM standard. Input power to the electron gun and melt rate were varied to observe their combined effect on extend of refining and loss of niobium. Electron beam (EB) melting is shown to reduce alkali metals, trace elements and interstitial impurities well below the specified limits. The reduction in the impurities during EB melting is attributed to evaporation and degassing due to the combined effect of high vacuum and high melt surface temperature. The % removal of interstitial impurities is essentially a function of melt rate and input power. As the melt rate decreases or input power increases, the impurity levels in the solidified niobium ingot decrease. The EB refining process is also accompanied by considerable amount of niobium loss, which is attributed to evaporation of pure niobium and niobium sub-oxide. Like other impurities, Nb loss increases with decreasing melt rate or increase in input power.

  12. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    SciTech Connect

    Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

    2008-08-22

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  13. Suprathermal electrons produced by beam-plasma-discharge

    NASA Technical Reports Server (NTRS)

    Sharp, W. E.

    1982-01-01

    Experiments conducted with a low energy plasma lens, HARP, in the electron beam of the large vacuum chamber at Johnson Space Center indicate that an enhanced population of 50 to 300 volt electrons appear when the beam goes into the Beam-Plasma Discharge (BPD) mode. Below the BPD instability the electron distribution appears to be characterized as non-energized single particle scattering and energy loss. At 100 cm from the beam core in the BPD mode the fluxes parallel to the beam are reduced by a factor of 20 with respect to the fluxes at 25 cm. Some evidence for isotropy near the beam core is presented.

  14. Two-Beam Instability in Electron Cooling

    SciTech Connect

    Burov, Alexey V.; /Fermilab

    2006-04-01

    The drift motion of cooling electrons makes them able to respond to transverse perturbations of a cooled ion beam. This response may lead to dipole or quadrupole transverse instabilities at specific longitudinal wave numbers. While the dipole instabilities can be suppressed by a combination of the Landau damping, machine impedance, and the active damper, the quadrupole and higher order modes can lead to either emittance growth, or a lifetime degradation, or both. The growth rates of these instabilities are strongly determined by the machine x-y coupling. Thus, tuning out of the coupling resonance and/or reduction of the machine coupling can be an efficient remedy for these instabilities.

  15. Graphene electronics for terahertz electron-beam radiation.

    PubMed

    Tantiwanichapan, Khwanchai; DiMaria, Jeff; Melo, Shayla N; Paiella, Roberto

    2013-09-20

    By virtue of their distinctive electronic properties (including linear energy dispersion, large velocity, and potentially ultra-high mobility even at room temperature), charge carriers in single-layer graphene are uniquely suited to radiation mechanisms that so far have been the primary domain of electron beams in vacuum-based systems. Here, we consider the use of sinusoidally corrugated graphene sheets for the generation of THz light based on a fundamentally new cyclotron-like radiation process, which does not require the application of any external magnetic field. Instead, periodic angular motion under bias is simply produced by the graphene mechanical corrugation, combined with its two-dimensional nature which ensures that the carrier trajectories perfectly conform to the corrugation. Numerical simulations indicate that technologically significant output power levels can correspondingly be obtained at geometrically tunable THz frequencies. This mechanism (as well as similar electron-beam radiation processes such as the Smith-Purcell and Cherenkov effects in periodic nanostructures) may open the way for a new family of THz optoelectronic devices based on graphene, including solid-state 'free-electron' lasers potentially capable of room-temperature operation.

  16. Generation and application of bessel beams in electron microscopy.

    PubMed

    Grillo, Vincenzo; Harris, Jérémie; Gazzadi, Gian Carlo; Balboni, Roberto; Mafakheri, Erfan; Dennis, Mark R; Frabboni, Stefano; Boyd, Robert W; Karimi, Ebrahim

    2016-07-01

    We report a systematic treatment of the holographic generation of electron Bessel beams, with a view to applications in electron microscopy. We describe in detail the theory underlying hologram patterning, as well as the actual electron-optical configuration used experimentally. We show that by optimizing our nanofabrication recipe, electron Bessel beams can be generated with relative efficiencies reaching 37±3%. We also demonstrate by tuning various hologram parameters that electron Bessel beams can be produced with many visible rings, making them ideal for interferometric applications, or in more highly localized forms with fewer rings, more suitable for imaging. We describe the settings required to tune beam localization in this way, and explore beam and hologram configurations that allow the convergences and topological charges of electron Bessel beams to be controlled. We also characterize the phase structure of the Bessel beams generated with our technique, using a simulation procedure that accounts for imperfections in the hologram manufacturing process.

  17. Space Charge Effect in the Sheet and Solid Electron Beam

    NASA Astrophysics Data System (ADS)

    Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung

    1998-11-01

    We analyze the space charge effect of two different types of electron beam ; sheet and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for sheet and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting current and space charge loading in each geometries.

  18. The electron beam instability and turbulence theories

    NASA Technical Reports Server (NTRS)

    Dum, C. T.

    1990-01-01

    Extensions and practical applications of recent observations of electron beam-plasma interactions are investigated for the range of turbulence theories, extending from quasi-linear to strong turbulence theory, which have been developed on the basis of the Langmuir-wave excitation model. Electron foreshock observations have indicated that linear instability theory must encompass the excitation of waves whose frequencies are substantially different from those of the plasma frequency; the point of departure for such extensions should be a quantitative test of existing theories, and particle simulations conducive to such testing are presented. A step-by-step addition of physical considerations is used in such simulation studies to differentiate among nonlinear turbulence effects.

  19. Focused electron beam induced deposition: A perspective

    PubMed Central

    Porrati, Fabrizio; Schwalb, Christian; Winhold, Marcel; Sachser, Roland; Dukic, Maja; Adams, Jonathan; Fantner, Georg

    2012-01-01

    Summary Background: Focused electron beam induced deposition (FEBID) is a direct-writing technique with nanometer resolution, which has received strongly increasing attention within the last decade. In FEBID a precursor previously adsorbed on a substrate surface is dissociated in the focus of an electron beam. After 20 years of continuous development FEBID has reached a stage at which this technique is now particularly attractive for several areas in both, basic and applied research. The present topical review addresses selected examples that highlight this development in the areas of charge-transport regimes in nanogranular metals close to an insulator-to-metal transition, the use of these materials for strain- and magnetic-field sensing, and the prospect of extending FEBID to multicomponent systems, such as binary alloys and intermetallic compounds with cooperative ground states. Results: After a brief introduction to the technique, recent work concerning FEBID of Pt–Si alloys and (hard-magnetic) Co–Pt intermetallic compounds on the nanometer scale is reviewed. The growth process in the presence of two precursors, whose flux is independently controlled, is analyzed within a continuum model of FEBID that employs rate equations. Predictions are made for the tunability of the composition of the Co–Pt system by simply changing the dwell time of the electron beam during the writing process. The charge-transport regimes of nanogranular metals are reviewed next with a focus on recent theoretical advancements in the field. As a case study the transport properties of Pt–C nanogranular FEBID structures are discussed. It is shown that by means of a post-growth electron-irradiation treatment the electronic intergrain-coupling strength can be continuously tuned over a wide range. This provides unique access to the transport properties of this material close to the insulator-to-metal transition. In the last part of the review, recent developments in mechanical strain

  20. Electron Beam Technology for Environmental Pollution Control.

    PubMed

    Chmielewski, Andrzej G; Han, Bumsoo

    2016-10-01

    Worldwide, there are over 1700 electron beam (EB) units in commercial use, providing an estimated added value to numerous products, amounting to 100 billion USD or more. High-current electron accelerators are used in diverse industries to enhance the physical and chemical properties of materials and to reduce undesirable contaminants such as pathogens, toxic byproducts, or emissions. Over the past few decades, EB technologies have been developed aimed at ensuring the safety of gaseous and liquid effluents discharged to the environment. It has been demonstrated that EB technologies for flue gas treatment (SO x and NO x removal), wastewater purification, and sludge hygienization can be effectively deployed to mitigate environmental degradation. Recently, extensive work has been carried out on the use of EB for environmental remediation, which also includes the removal of emerging contaminants such as VOCs, endocrine disrupting chemicals (EDCs), and potential EDCs.

  1. Mask Fabrication Using Electron Beam Exposure System

    NASA Astrophysics Data System (ADS)

    Watakabe, Y.; Shigetomi, A.; Morimoto, H.; Kato, T.

    1981-07-01

    This study describes the results of feature size distribution, pattern location accuracy and level to level registration error on chrominum master masks fabricated by EeBES-40. This system has the capability of high speed electron beam blanking at 40MHz, the capacity for large size masks (with 6 inch mask cassette), and the automatic cassette handling system. OEBR-100(PGMA), as the electron beam negative resist, is used for 5 inch and 6 inch chrominum masks. The chrominum etching process is used for both wet and dry plasma technology. Test patterns and 64 K bit memory TEG, as the practical pattern, are used in this study. More than 40 measurements are taken, uniformly distributed over 96 to 112mm square, and the feature size distribution is measured by a laser interferometer X-Y measuring system. Pattern location accuracy and level to level registration error are obtained using EeBES-40 quality assurance programs called MARKET/PLOTMARKET. This program operates by scanning over the resist image of the test pattern, utilizing the normal fiducial mark location hardware. The followinc results are obtained; (1) Feature size distribution within 6 inch mask : -/+0.1 μm (2) Level-to-level registration error2 : less than 0.1 pm High quality masks with about 0.02 defects/cm2 , and rapid throughput of 6 hr./10 masks using the auto-matic 10-cassette handling system are obtained.

  2. Polarization of a stored electron beam

    SciTech Connect

    Chao, A.W.

    1981-07-01

    Synchrotron radiation by a point charge is a familiar subject in classical electrodynamics. Perhaps less familiar are some quantum mechanical corrections to the classical results. Some of those quantum aspects of synchrotron radiation are described. One of the quantum effects leads to the expectation that electrons in a storage ring will polarize themselves to 92% - a surprisingly high value. A semi-classical derivation of the quantum effects is given. An effort has been made to minimize the need of using quantum mechanics. Results are put together to derive a final expression of beam polarization. Conditions under which the expected 92% polarization is destroyed are found and attributed to depolarization resonances. The various depolarization mechanisms are first illustrated by an idealized example and then systematically treated by a matrix formalism. It is shown that the strength of depolarization is specified by a key quantity called the spin chromaticity. Finally as an application of the obtained results, an estimate of the achievable level of beam polarization for two existing electron storage rings, SPEAR and PEP, is given.

  3. Atomic Image Projection Electron Beam Lithography

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Bum

    2006-03-01

    While we are approaching to the nanotechnology era, as was proposed by Richard Feynman in 1959, our main concern still lies in how one can controllably manufacture and utilize nanometer scale features. The top-down approaches, most notably, lithography based techniques still have the problem of throughput although it has been successfully demonstrate to make features with the size less than 10 nm. The bottom-up approaches, either utilizing chemical vapor deposition process to make carbon nanotube or wet-chemical process to make size controllable quantum dots and rods, still have the limitation of extending it to many different types of materials and also delivering them on a wafer size substrate to make nanodevices. In this talk, we will propose a novel electron beam lithography technique to make nanometer scale features. The novelty of this process lies in the fact that one can utilize the crystalline lattice image commonly observed by the high resolution transmission electron microscopy as an ultimate mask to generate nanometer scale patterns. Using this technique, we demonstrate that down to 45 nm pitch size can be resolved on hydrogen silsesquioxine (HSQ) e-beam resist material. The patterns are formed on Si substarte with the dot size of about 30 nm and the line size of about 25 nm. This technique can be extend to define less than 10 nm size features only if the suitable resist is developed.

  4. The polarized electron beam at ELSA

    NASA Astrophysics Data System (ADS)

    Hoffmann, M.; Drachenfels, W. V.; Frommberger, F.; Gowin, M.; Helbing, K.; Hillert, W.; Husmann, D.; Keil, J.; Michel, T.; Naumann, J.; Speckner, T.; Zeitler, G.

    2001-06-01

    The future medium energy physics program at the electron stretcher accelerator ELSA of Bonn University mainly relies on experiments using polarized electrons in the energy range from 1 to 3.2 GeV. To provide a polarized beam with high polarization and sufficient intensity a dedicated source has been developed and set into operation. To prevent depolarization during acceleration in the circular accelerators several depolarizing resonances have to be corrected for. Intrinsic resonances are compensated using two pulsed betatron tune jump quadrupoles. The influence of imperfection resonances is successfully reduced applying a dynamic closed orbit correction in combination with an empirical harmonic correction on the energy ramp. In order to minimize beam depolarization, both types of resonances and the correction techniques have been studied in detail. It turned out that the polarization in ELSA can be conserved up to 2.5 GeV and partially up to 3.2 GeV which is demonstrated by measurements using a Møller polarimeter installed in the external GDH1-beamline. .

  5. Proximity correction for electron beam lithography

    NASA Astrophysics Data System (ADS)

    Marrian, Christie R.; Chang, Steven; Peckerar, Martin C.

    1996-09-01

    As the critical dimensions required in mask making and direct write by electron beam lithography become ever smaller, correction for proximity effects becomes increasingly important. Furthermore, the problem is beset by the fact that only a positive energy dose can be applied with an electron beam. We discuss techniques such as chopping and dose shifting, which have been proposed to meet the positivity requirement. An alternative approach is to treat proximity correction as an optimization problem. Two such methods, local area dose correction and optimization using a regularizer proportional to the informational entropy of the solution, are compared. A notable feature of the regularized proximity correction is the ability to correct for forward scattering by the generation of a 'firewall' set back from the edge of a feature. As the forward scattering width increases, the firewall is set back farther from the feature edge. The regularized optimization algorithm is computationally time consuming using conventional techniques. However, the algorithm lends itself to a microelectronics integrated circuit coprocessor implementation, which could perform the optimization faster than even the fastest work stations. Scaling the circuit to larger number of pixels is best approached with a hybrid serial/parallel digital architecture that would correct for proximity effects over 108 pixels in about 1 h. This time can be reduced by simply adding additional coprocessors.

  6. Analysis of Beam-Beam Kink Instability in a Linac-Ring Electron-Ion Collider

    SciTech Connect

    V. Lebedev; J. Bisognano; R. Li; B. Yunn

    2001-06-01

    A linac-ring collision scheme was considered in recent proposals of electron-gold colliders (eRHIC) and polarized-electron light-ion colliders (EPIC). The advantages of using an energy-recovered linac for the electron beam is that it avoids the limitation of beam-beam tune shift inherent in a storage ring, pertains good beam quality and easy manipulation of polarization. However, the interaction of the ion beam in the storage ring with the electron beam from the linac acts analogously to a transverse impedance, and can induce unstable behavior of the ion beam similar to the strong head-tail instability. In this paper, this beam-beam kink instability with head-tail effect is analyzed using the linearized Vlasov equation, and the threshold of transverse mode coupling instability is obtained.

  7. Electron beam diagnostic for space charge measurement of an ion beam

    SciTech Connect

    Roy, Prabir K.; Yu, Simon S.; Henestroza, Enrique; Eylon, Shmuel; Shuman, Derek B.; Ludvig, Jozsef; Bieniosek, Frank M.; Waldron, William L.; Greenway, Wayne G.; Vanecek, David L.; Hannink, Ryan; Amezcua, Monserrat

    2004-09-25

    A non-perturbing electron beam diagnostic system for measuring the charge distribution of an ion beam is developed for Heavy Ion Fusion (HIF) beam physics studies. Conventional diagnostics require temporary insertion of sensors into the beam, but such diagnostics stop the beam, or significantly alter its properties. In this diagnostic a low energy, low current electron beam is swept transversely across the ion beam; the measured electron beam deflection is used to infer the charge density profile of the ion beam. The initial application of this diagnostic is to the Neutralized Transport Experiment (NTX), which is exploring the physics of space-charge-dominated beam focusing onto a small spot using a neutralizing plasma. Design and development of this diagnostic and performance with the NTX ion beamline is presented.

  8. Electron energy distribution produced by beam-plasma discharge

    NASA Technical Reports Server (NTRS)

    Anderson, H. R.; Gordeuk, J.; Jost, R. J.

    1982-01-01

    In an investigation of a beam-plasma discharge (BPD), the electron energy distribution of an electron beam moving through a partially ionized gas is analyzed. Among other results, it is found that the occurrence of BPD heats the initially cold electron beam from the accelerator. The directional intensity of electrons measured outside the beam core indicates that most particles suffer a single scattering in energy and pitch angle. At low currents this result is expected as beam particles collide with the neutral atmosphere, while in BPD the majority of particles is determined to still undergo a single scattering near the original beam core. The extended energy spectra at various beam currents show two rather distinct plasma populations, one centered at the initial beam energy (approximately 1500 eV) and the other at approximately 150 eV.

  9. Electron acceleration by a tightly focused cylindrical vector Gaussian beam

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Yang, Zhen-Jun; Li, Jian-Xing; Zang, Wei-Ping

    2017-02-01

    We have studied the electron acceleration by a tightly focused cylindrical vector Gaussian beam. Different from the Lax series field, cylindrical vector Gaussian beams are vector-beam solutions of Maxwell’s equations and its focusing property can be numerically analyzed by the Richards-Wolf vectorial diffraction theory. Field differences exist between the cylindrical vector Gaussian beam and the Lax series field. The cylindrical vector Gaussian beam increases the asymmetry of the electromagnetic fields, which is more beneficial to the electron acceleration. When the beam waist falls down to the order of the wavelength, the high laser intensity zone is more proper to define the reflection, capture and transmission conditions of the electrons. The injection energy and the injected angle of the electron and the initial phase of the laser beam play important roles for the electron to enter and be trapped by the high laser intensity zone.

  10. Cherenkov Light-based Beam Profiling for Ultrarelativistic Electron Beams

    SciTech Connect

    Adli, E.; Gessner, S. J.; Corde, S.; Hogan, M. J.; Bjerke, H. H.

    2015-02-09

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. Furthermore, the profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. Finally, we report on the measured performance of this profile monitor.

  11. Effective NOx remediation from a surrogate flue gas using the US NRL Electra electron beam facility

    NASA Astrophysics Data System (ADS)

    Petrova, Tz. B.; Petrov, G. M.; Wolford, M. F.; Giuliani, J. L.; Ladouceur, H. D.; Hegeler, F.; Myers, M. C.; Sethian, J. D.

    2017-02-01

    Nitric oxide (NOx) emission is under restrictive federal regulations because of its negative impact on atmosphere, biosphere, and human health. Therefore, its removal has been a subject of extensive research to develop new efficient and cost effective techniques that can be applied on an industrial scale. In this work, we study both experimentally and theoretically an effective removal of NOx pollutants from a surrogate flue gas (SFG) using high power electron beam (e-beam) pulses. SFG is a simulant for exhaust from coal combustion power plants (82% N2, 6% O2, 12% CO2, and ˜100 ppm of NOx). The pulsed electron beam is generated using the United States Naval Research Laboratory Electra facility, which delivers e-beams with energies of ˜500 keV and a power pulse duration of ˜140 ns. During the e-beam irradiation, the energetic electrons generate a non-equilibrium plasma containing chemically active species, which then react with NOx to form harmless substances. A non-equilibrium time-dependent model is developed to describe NOx remediation from SFG. The model combines e-beam deposition rates obtained by solving the electron Boltzmann equation and extensive plasma chemistry modeling, which follows the species on a time scale from sub-nanoseconds to a few seconds. NOx decomposition as a function of electron beam parameters is studied. It is demonstrated experimentally that short (ns) pulses are the most efficient for NOx removal. A sharp reduction of NOx was measured with e-beam power deposition increasing, following the trend predicted by the model, achieving a 20 fold reduction to ˜5 ppm at energy deposition ˜20 J/l.

  12. Novel vortex generator and mode converter for electron beams.

    PubMed

    Schattschneider, P; Stöger-Pollach, M; Verbeeck, J

    2012-08-24

    A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with a topological charge m=±1 into beams closely resembling Hermite-Gaussian HG(10) and HG(01) modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a plane wave into modes with topological charge m=±1. This combination serves as a generator of electron vortex beams of high brilliance.

  13. A self-consistent quasistatic equilibrium for non-neutral diamagnetic electron vortices

    SciTech Connect

    Church, B.W.; Sudan, R.N.

    1995-06-01

    A self-consistent quasistatic equilibrium for a non-neutral cylindrical electron vortex has been found using the two-dimensional relativistic electron fluid equations. While other work on electron vortices considered a regime where the vortex radius is much smaller than the collisionless skin depth {lambda}={ital c}/{omega}{sub {ital p}}, this equilibrium is valid for large-radius, diamagnetic vortices and predicts a maximum radius of 2{sup 3/2}{lambda} for a highly relativistic electron vortex. The vortex model shows good agreement with observations of diamagnetic electron vortices in two-dimensional electromagnetic particle-in-cell simulations of magnetically insulated transmission lines.

  14. Electron-Beam Dynamics for an Advanced Flash-Radiography Accelerator

    DOE PAGES

    Ekdahl, Carl

    2015-11-17

    Beam dynamics issues were assessed for a new linear induction electron accelerator being designed for multipulse flash radiography of large explosively driven hydrodynamic experiments. Special attention was paid to equilibrium beam transport, possible emittance growth, and beam stability. Especially problematic would be high-frequency beam instabilities that could blur individual radiographic source spots, low-frequency beam motion that could cause pulse-to-pulse spot displacement, and emittance growth that could enlarge the source spots. Furthermore, beam physics issues were examined through theoretical analysis and computer simulations, including particle-in-cell codes. Beam instabilities investigated included beam breakup, image displacement, diocotron, parametric envelope, ion hose, and themore » resistive wall instability. The beam corkscrew motion and emittance growth from beam mismatch were also studied. It was concluded that a beam with radiographic quality equivalent to the present accelerators at Los Alamos National Laboratory will result if the same engineering standards and construction details are upheld.« less

  15. Experimental study of the stability of a neutralized electron beam

    SciTech Connect

    Kudelainen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1983-05-01

    Results are reported from measurements of the spectral properties of a long neutralized electron beam in the NAP-M proton storage ring. It is shown that when the number of secondary electrons is small, both the longitudinal and the transverse oscillations are strongly damped, so that beam instability is suppressed. The current density of the neutralized electron beam produced in the experiments was approx.10/sup 2/ times greater than the theoretical value determined from the instability threshold for nonaxisymmetric oscillations.

  16. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    SciTech Connect

    Grillo, Vincenzo; Mafakheri, Erfan; Frabboni, Stefano

    2014-01-27

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.

  17. Study on electron beam in a low energy plasma focus

    SciTech Connect

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  18. Development of hollow electron beams for proton and ion collimation

    SciTech Connect

    Stancari, G.; Drozhdin, A.I.; Kuznetsov, G.; Shiltsev, V.; Still, D.A.; Valishev, A.; Vorobiev, L.G.; Assmann, R.; Kabantsev, A.; /UC, San Diego

    2010-06-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  19. Effect of electron beam irradiation on PMMA films

    SciTech Connect

    Tiwari, Pragya; Srivastava, A. K.; Khattak, B. Q.; Verma, Suveer; Upadhyay, Anuj; Sinha, A. K.; Ganguli, Tapas; Lodha, G. S.; Deb, S. K.

    2012-06-05

    Polymethyl methacrylate (PMMA) is characterized for electron beam interactions in the resist layer in lithographic applications. PMMA thin films (free standing) were prepared by solvent casting method. These films were irradiated with 30keV electron beam at different doses. Structural and chemical properties of the films were studied by means of X-ray diffraction and Fourier transform infra-red (FTIR) spectroscopy The XRD results showed that the amorphization increases with electron beam irradiation dose. FTIR spectroscopic analysis reveals that electron beam irradiation promotes the scission of carbonyl group and depletes hydrogen and converts polymeric structure into hydrogen depleted carbon network.

  20. Electron beam accelerator with magnetic pulse compression and accelerator switching

    DOEpatents

    Birx, D.L.; Reginato, L.L.

    1984-03-22

    An electron beam accelerator is described comprising an electron beam generator-injector to produce a focused beam of greater than or equal to .1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electron by about .1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially .1-1 MeV maximum energy over a time duration of less than or equal to 1 ..mu..sec.

  1. Effect of Electron Beam Irradiation on Tensile Strength of Polypropylene

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroshi; Ikeda, Masayuki; Shimbo, Minoru; Miyano, Yasushi

    In this paper, the effects of the intensity of electron beam and the variation with time after irradiation of electron beam on the tensile strength of the polypropylene (PP), which is widely used as medicine containers, were investigated. PP with and without colorants were used first and samples irradiated under various intensity of EB. A tensile test on the irradiated samples with elapsed time after the irradiation of the electron beam was carried out. The effects of those factors on the tensile strength were discussed. The following results were obtained (1) The tensile strength of PP decreased due to the influence of the electron beam irradiation, however the rate of the decrease in strength was small compared with the original one. Furthermore, the rate of the decrease in strength was very small owing to the variation with time after the EB irradiation. (2) The tensile rupture strength of PP increased and the rupture strain owing to the influence of the electron beam irradiation compared with the original one. In addition, these rupture strength increased and the rupture strain decreased along with time after the irradiation of the electron beam. (3) The tensile rupture strain energy of PP decreased owing to the influence of the electron beam irradiation compared with the original one. In addition, the strain energy decreases with time after the irradiation of the electron beam. Moreover, the strength characteristics of PP with colorants received greater influence of electron beam compared with the one without colorants.

  2. Electron beam accelerator with magnetic pulse compression and accelerator switching

    DOEpatents

    Birx, Daniel L.; Reginato, Louis L.

    1987-01-01

    An electron beam accelerator comprising an electron beam generator-injector to produce a focused beam of .gtoreq.0.1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electrons by about 0.1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially 0.1-1 MeV maximum energy over a time duration of .ltoreq.1 .mu.sec.

  3. Electron beam accelerator with magnetic pulse compression and accelerator switching

    DOEpatents

    Birx, Daniel L.; Reginato, Louis L.

    1988-01-01

    An electron beam accelerator comprising an electron beam generator-injector to produce a focused beam of .gtoreq.0.1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electrons by about 0.1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially .gtoreq.0.1-1 MeV maximum energy over a time duration of .ltoreq.1 .mu.sec.

  4. Electron-beam direct processing on living cell membrane

    SciTech Connect

    Hoshino, Takayuki; Morishima, Keisuke

    2011-10-24

    We demonstrated a direct processing on a living Hep G2 cell membrane in conventional cultivation conditions using an electron beam. Electron beam-induced deposition from liquid precursor 3,4-ethylenedioxythiophene and ablation was performed on the living cells. The 2.5-10 keV electron beam which was irradiated through a 100-nm-thick SiN nanomembrane could induce a deposition pattern and a ablation on a living cell membrane. This electron beam direct processing can provide simple in-situ cell surface modification for an analytical method of living cell membrane dynamic.

  5. Patterning and imaging with electrons: assessing multi-beam SEM for e-beam structured CMOS samples

    NASA Astrophysics Data System (ADS)

    Garbowski, Tomasz; Panteleit, Friedhelm; Dellemann, Gregor; Gutsch, Manuela; Hohle, Christoph; Reich, Elke; Rudolph, Matthias; Steidel, Katja; Thrun, Xaver; Zeidler, Dirk

    2016-03-01

    Electron optics can assist in the fabrication of semiconductor devices in many challenges that arise from the ongoing decrease of structure size. Examples are augmenting optical lithography by electron beam direct write strategies and high-throughput imaging of patterned structures with multiple beam electron microscopes. We use multiple beam electron microscopy to image semiconductor wafers processed by electron beam lithography.

  6. Electron beam diagnostic system using computed tomography and an annular sensor

    DOEpatents

    Elmer, John W.; Teruya, Alan T.

    2014-07-29

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  7. Electron beam diagnostic system using computed tomography and an annular sensor

    DOEpatents

    Elmer, John W.; Teruya, Alan T.

    2015-08-11

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  8. Prevention of electron beam transmittance for biological cell imaging using electron beam excitation-assisted optical microscope

    NASA Astrophysics Data System (ADS)

    Fukuta, Masahiro; Nawa, Yasunori; Inami, Wataru; Kawata, Yoshimasa

    2016-12-01

    We demonstrated the high-spatial-resolution imaging of label-free biological cells using an electron beam excitation-assisted optical (EXA) microscope without irradiation damage by the electron beam. An EXA microscope can be used to observe a specimen with a nanometric light source excited in the Si3N4 membrane by an electron beam. The incident electron beam penetrates the Si3N4 membrane and damages the specimen. To suppress the irradiation damage of the specimen, we prevented the transmittance of the electron beam by coating the Si3N4 membrane with a gold thin film. To obtain an electron beam transmittance through the Si3N4 of 0%, a gold film of 15 nm thickness was required. By adding the gold layer, a label-free cellular structure was observed with 135-nm spatial resolution.

  9. Electron beam magnetic switch for a plurality of free electron lasers

    DOEpatents

    Schlitt, Leland G.

    1984-01-01

    Apparatus for forming and utilizing a sequence of electron beam segments, each of the same temporal length (substantially 15 nsec), with consecutive beams being separated by a constant time interval of the order of 3 nsec. The beam sequence is used for simultaneous inputs to a plurality of wiggler magnet systems that also accept the laser beams to be amplified by interaction with the co-propagating electron beams. The electron beams are arranged substantially in a circle to allow proper distribution of and simultaneous switching out of the beam segments to their respective wiggler magnets.

  10. Cherenkov Light-based Beam Profiling for Ultrarelativistic Electron Beams

    DOE PAGES

    Adli, E.; Gessner, S. J.; Corde, S.; ...

    2015-02-09

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. Furthermore, the profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. Finally,more » we report on the measured performance of this profile monitor.« less

  11. Current understanding and issues on electron beam injection in space

    NASA Technical Reports Server (NTRS)

    Papadopoulos, K.; Szuszczewicz, E. P.

    1988-01-01

    The status of the physics understanding involved in electron beam injection in space is reviewed. The paper examines our understanding of beam plasma interactions and their associated wave and energized particle spectra of the processes involved in the beam plasma discharge, and of the vehicle charge neutralization. 'Strawman' models are presented for comparison with experimental observations.

  12. Measurement of the electron beam mode in earth's foreshock

    NASA Technical Reports Server (NTRS)

    Onsager, T. G.; Holzworth, R. H.

    1990-01-01

    High frequency electric field measurements from the AMPTE IRM plasma wave receiver are used to identify three simultaneously excited electrostatic wave modes in the earth's foreshock region: the electron beam mode, the Langmuir mode, and the ion acoustic mode. A technique is developed which allows the rest frame frequecy and wave number of the electron beam waves to be determined. It is shown that the experimentally determined rest frame frequency and wave number agree well with the most unstable frequency and wave number predicted by linear homogeneous Vlasov theory for a plasma with Maxwellian background electrons and a Lorentzian electron beam. From a comparison of the experimentally determined and theoretical values, approximate limits are put on the electron foreshock beam temperatures. A possible generation mechanism for ion acoustic waves involving mode coupling between the electron beam and Langmuir modes is also discussed.

  13. Monoenergetic collimated nano-Coulomb electron beams driven by crossed laser beams

    SciTech Connect

    Wang Jingwei; Murakami, M.; Weng, S. M.; Ruhl, H.; Luan Shixia; Yu Wei

    2013-07-08

    Monoenergetic collimated electron acceleration by two crossed laser beams is investigated through an analytical model and particle-in-cell simulations. Electron bunches with a total charge of order nano-Coulombs are accelerated by the axial electric field formed by the crossed laser beams to nearly 760 MeV with an energy spread of 2.7%. The transverse components of both electric and magnetic fields vanish along the axis, making the electron beam highly collimated. This acceleration scheme appears promising in producing high quality electron beams.

  14. Gridded Electron Guns and Modulation of Intense Beams

    SciTech Connect

    Harris, J R; O'Shea, P G

    2006-05-02

    Gridded guns are useful for producing modulated electron beams. This modulation is generally limited to simple gating of the beam, but may be used to apply structure to the beam pulse shape. In intense beams, this structure spawns space charge waves whose dynamics depend in part on the relative strengths of the velocity and density variations which comprise the initial current modulation. In this paper, we calculate the strengths of beam current and velocity modulation produced in a gridded electron gun, and show that under normal conditions the initial modulation is dominated by density variation rather than velocity variation.

  15. Quantum effects in electron beam pumped GaAs

    SciTech Connect

    Yahia, M. E.; Azzouz, I. M.; Moslem, W. M.

    2013-08-19

    Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.

  16. Annular-beam, 17 GHz free-electron maser experiment

    SciTech Connect

    Earley, L.M.; Carlsten, B.E.; Fazio, M.V.

    1997-06-01

    Experiments have been conducted on a 15-17 GHz free electron maser (FEM) for producing a 500 MW output pulse with a phase stability appropriate for linear collider applications. The electron beam source was a 1 {mu}s, 800 kV, 5 kA, 6-cm-dia annular electron beam machine called BANSHEE. The beam interacted with the TM{sub 02} and TM{sub 03} mode Raman FEM amplifier in a corrugated cylindrical waveguide where the beam runs close to the interaction device walls to reduce the power density in the fields. This greatly reduced the kinetic energy loss caused by the beam potential depression associated with the space charge which was a significant advantage in comparison with conventional solid beam microwave tubes at the same beam current. The experiment was operated in a single shot mode with a large number of diagnostics to measure power, frequency and energy.

  17. Patient radiation doses for electron beam CT

    SciTech Connect

    Castellano, Isabel A.; Dance, David R.; Skinner, Claire L.; Evans, Phil M.

    2005-08-15

    A Monte Carlo based computer model has been developed for electron beam computed tomography (EBCT) to calculate organ and effective doses in a humanoid hermaphrodite phantom. The program has been validated by comparison with experimental measurements of the CT dose index in standard head and body CT dose phantoms; agreement to better than 8% has been found. The robustness of the model has been established by varying the input parameters. The amount of energy deposited at the 12:00 position of the standard body CT dose phantom is most susceptible to rotation angle, whereas that in the central region is strongly influenced by the beam quality. The program has been used to investigate the changes in organ absorbed doses arising from partial and full rotation about supine and prone subjects. Superficial organs experience the largest changes in absorbed dose with a change in subject orientation and for partial rotation. Effective doses for typical clinical scan protocols have been calculated and compared with values obtained using existing dosimetry techniques based on full rotation. Calculations which make use of Monte Carlo conversion factors for the scanner that best matches the EBCT dosimetric characteristics consistently overestimate the effective dose in supine subjects by typically 20%, and underestimate the effective dose in prone subjects by typically 13%. These factors can therefore be used to correct values obtained in this way. Empirical dosimetric techniques based on the dose-length product yield errors as great as 77%. This is due to the sensitivity of the dose length product to individual scan lengths. The magnitude of these errors is reduced if empirical dosimetric techniques based on the average absorbed dose in the irradiated volume (CTDI{sub vol}) are used. Therefore conversion factors specific to EBCT have been calculated to convert the CTDI{sub vol} to an effective dose.

  18. Electron beam enhanced surface modification for making highly resolved structures

    DOEpatents

    Pitts, John R.

    1986-01-01

    A method for forming high resolution submicron structures on a substrate is provided by direct writing with a submicron electron beam in a partial pressure of a selected gas phase characterized by the ability to dissociate under the beam into a stable gaseous leaving group and a reactant fragment that combines with the substrate material under beam energy to form at least a surface compound. Variations of the method provide semiconductor device regions on doped silicon substrates, interconnect lines between active sites, three dimensional electronic chip structures, electron beam and optical read mass storage devices that may include color differentiated data areas, and resist areas for use with selective etching techniques.

  19. High harmonic terahertz confocal gyrotron with nonuniform electron beam

    SciTech Connect

    Fu, Wenjie; Guan, Xiaotong; Yan, Yang

    2016-01-15

    The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.

  20. Electron beam enhanced surface modification for making highly resolved structures

    DOEpatents

    Pitts, J.R.

    1984-10-10

    A method for forming high resolution submicron structures on a substrate is provided by direct writing with a submicron electron beam in a partial pressure of a selected gas phase characterized by the ability to dissociate under the beam into a stable gaseous leaving group and a reactant fragment that combines with the substrate material under beam energy to form at least a surface compound. Variations of the method provide semiconductor device regions on doped silicon substrates, interconnect lines between active sites, three dimensional electronic chip structures, electron beam and optical read mass storage devices that may include color differentiated data areas, and resist areas for use with selective etching techniques.

  1. Potential for Fabric Damage by Welding Electron Beam

    NASA Technical Reports Server (NTRS)

    Fragomeni, James M.; Nunes, Arthur C., Jr.

    1998-01-01

    Welding electron beam effects on Nextel AF-62 ceramic fabric enable a preliminary, tentative interpretation of electron beam fabric damage. Static surface charging does not protect fabric from beam penetration, but penetration occurs only after a delay time. The delay time is thought to be that required for the buildup of outgassing products at the fabric surface to a point where arcing occurs. Extra long delays are noted when the gun is close enough to the surface to be shut off by outgassing emissions. Penetration at long distances is limited by beam attenuation from electronic collisions with the chamber atmosphere.

  2. XUV and Xray Diagnostics of Relativistic Electron Beam Generated Plasmas.

    DTIC Science & Technology

    1982-02-08

    crystals. No-Screen and Type T x-ray films were used to record the spectra, and available sen- 1’) sitometric data was used to relate film densities...ELECTRON TEMPERATURE (eV) Fig. 21 - A local thermodynamic equilibrium calculation of the ratio of two argon lines vs. electron temperature. The electron

  3. A Investigation of Radiotherapy Electron Beams Using Monte Carlo Techniques

    NASA Astrophysics Data System (ADS)

    Ding, George X.

    1995-01-01

    Radiotherapy electron beams are more complicated than photon beams due to variations in the beam production, the scattering of low-energy electrons, and the presence contaminant photons. The detailed knowledge of a radiotherapy beam is essential to an accurate calculation of dose distribution for a treatment planning system. This investigation aims to enhance our understanding of radiotherapy beams by focusing on electron beams used in radiotherapy. It starts with a description of the Monte Carlo simulation code, BEAM, and a detailed simulation of an accelerator head to obtain realistic radiotherapy beams. The simulation covers electron beams from various accelerators, including the NRC research accelerator, the NPL (UK), accelerator, A Varian Clinac 2100C, a Philips SL75-20, a Siemens KD2, an AECL Therac 20, and a Scanditronix MM50. The beam energies range from 4 to 50 MeV. The EGS4 user code, BEAM, is extensively benchmarked against experiment by comparing calculated dose distributions with measured dose distributions in water. The simulated beams are analyzed to obtain the characteristics of various electron beams from a variety of accelerators. The simulated beams are also used as inputs to calculate the following parameters: the mean electron energy, the most probable energy, the energy-range relationships, the depth-scaling factor to convert depths in plastic to water-equivalent depths, the water-to-air stopping-power ratios, and the electron fluence correction factors used to convert dose measured in plastics to dose in water. These parameters are essential for electron beam dosimetry. The results from this study can be applied in cancer clinics to improve the accuracy of the absolute dosimetry. The simulation also provides information about the backscatter into the beam monitor chamber, and predicts the influence on the beam output factors. This investigation presents comprehensive data on the clinical electron beams, and answers many questions which could

  4. NOx reduction by electron beam-produced nitrogen atom injection

    DOEpatents

    Penetrante, Bernardino M.

    2002-01-01

    Deactivated atomic nitrogen generated by an electron beam from a gas stream containing more than 99% N.sub.2 is injected at low temperatures into an engine exhaust to reduce NOx emissions. High NOx reduction efficiency is achieved with compact electron beam devices without use of a catalyst.

  5. Practical Implications of Electron-Beam Surface Melting

    NASA Astrophysics Data System (ADS)

    Lewis, Brian G.; Strutt, Peter R.

    1982-11-01

    The use of laser/electron-beam techniques to glaze large surface areas is briefly reviewed. The properties thus obtained for a range of iron-based alloys is discussed. Recent results show that electron-beam glazing can extend the wear life of certain cemented carbide materials and preliminary results indicate that glazed tool steels show enhanced corrosion resistance.

  6. Electron Beam-Cure Polymer Matrix Composites: Processing and Properties

    NASA Technical Reports Server (NTRS)

    Wrenn, G.; Frame, B.; Jensen, B.; Nettles, A.

    2001-01-01

    Researchers from NASA and Oak Ridge National Laboratory are evaluating a series of electron beam curable composites for application in reusable launch vehicle airframe and propulsion systems. Objectives are to develop electron beam curable composites that are useful at cryogenic to elevated temperatures (-217 C to 200 C), validate key mechanical properties of these composites, and demonstrate cost-saving fabrication methods at the subcomponent level. Electron beam curing of polymer matrix composites is an enabling capability for production of aerospace structures in a non-autoclave process. Payoffs of this technology will be fabrication of composite structures at room temperature, reduced tooling cost and cure time, and improvements in component durability. This presentation covers the results of material property evaluations for electron beam-cured composites made with either unidirectional tape or woven fabric architectures. Resin systems have been evaluated for performance in ambient, cryogenic, and elevated temperature conditions. Results for electron beam composites and similar composites cured in conventional processes are reviewed for comparison. Fabrication demonstrations were also performed for electron beam-cured composite airframe and propulsion piping subcomponents. These parts have been built to validate manufacturing methods with electron beam composite materials, to evaluate electron beam curing processing parameters, and to demonstrate lightweight, low-cost tooling options.

  7. Electron Gun For Multiple Beam Klystron Using Magnetic Focusing

    DOEpatents

    Ives, R. Lawrence; Miram, George; Krasnykh, Anatoly

    2004-07-27

    An RF device comprising a plurality of drift tubes, each drift tube having a plurality of gaps defining resonant cavities, is immersed in an axial magnetic field. RF energy is introduced at an input RF port at one of these resonant cavities and collected at an output RF port at a different RF cavity. A plurality of electron beams passes through these drift tubes, and each electron beam has an individual magnetic shaping applied which enables confined beam transport through the drift tubes.

  8. Waves in relativistic electron beam in low-density plasma

    NASA Astrophysics Data System (ADS)

    Sheinman, I.; Sheinman (Chernenco, J.

    2016-11-01

    Waves in electron beam in low-density plasma are analyzed. The analysis is based on complete electrodynamics consideration. Dependencies of dispersion laws from system parameters are investigated. It is shown that when relativistic electron beam is passed through low-density plasma surface waves of two types may exist. The first type is a high frequency wave on a boundary between the beam and neutralization area and the second type wave is on the boundary between neutralization area and stationary plasma.

  9. Electron beam control using shock-induced density downramp injection

    NASA Astrophysics Data System (ADS)

    Swanson, K.; Tsai, H.-E.; Barber, S.; Lehe, R.; Mao, H.-S.; Steinke, S.; van Tilborg, J.; Geddes, C. G. R.; Leemans, W. P.

    2017-03-01

    In these experiments, we improve the quality of electrons injected along a shock-induced density downramp. We demonstrate that beam ellipticity and steering are influenced by the shock front tilt, and we present simple models to explain these effects. By adjusting the shock front angle, we minimize the beam's off-axis steering and ellipticity, producing high-quality electron beams over a tunable energy range.

  10. Study of non-equilibrium electron dynamics in metals

    NASA Astrophysics Data System (ADS)

    Ibrahim, Wael Mohamed Gomaa

    Thermal phenomena, such as heat propagation, lattice melting, and ablation, are the result of energy deposition in metals. A fundamental understanding of the electron dynamics leading to these thermal phenomena would benefit many laser applications, such as laser deposition of thin films and laser processing. In this work, thin metal films were prepared using the resistive heating evaporation technique. High dynamic range autocorrelators were constructed to characterize the different laser systems used in this study. The nonequilibrium electron dynamics in single layer gold films, multi-layer gold-vanadium, and gold-titanium films were studied. The time evolution of the electron temperature was monitored using femtosecond time-resolved thermoreflectivity (DeltaR/R) measurements. The validity of the Two-Temperature Model (TTM) in describing ultrafast laser heating processes was checked. The effect of the padding layer on the surface damage threshold was investigated. The experimental results revealed a reduction of the thermoreflectivity signal, DeltaRmax, for the multi-layer film that signifies a reduction in the surface electron temperature. Multi-shot damage experiments, in contrast to the thermoreflectivity measurements and the results of Qiu et al., showed no evidence of surface damage in the case of the gold sample, whereas the multi-layer sample experienced an onset of surface damage at the same experimental conditions. The suitability of the Two-Temperature Model (TTM) in describing the transport and relaxation dynamics of hot electrons accurately was verified. A new methodology for the correction of the TTM to account for the internal thermalization of the electron gas and convolution effects was achieved.

  11. Thermal effect on prebunched two-beam free electron laser

    NASA Astrophysics Data System (ADS)

    Mirian, N. S.; Maraghechi, B.

    2013-08-01

    A numerical simulation in one-dimension is conducted to study the two-beam free electron laser. The fundamental resonance of the fast electron beam coincides with the fifth harmonic of the slow electron beam in order to generate extreme ultraviolet radiation. Thermal effect in the form of the longitudinal velocity spread is included in the analysis. In order to reduce the length of the wiggler, prebunched slow electron beam is considered. The evaluation of the radiation power, bunching parameter, distribution function of energy, and the distribution function of the pondermotive phase is studied. Sensitivity of the power of the fifth harmonic to the jitter in the energy difference between the two beams is also studied. A phase space is presented that shows the trapped electrons at the saturation point.

  12. Spin-Polarizing Interferometric Beam Splitter for Free Electrons.

    PubMed

    Dellweg, Matthias M; Müller, Carsten

    2017-02-17

    A spin-polarizing electron beam splitter is described that relies on an arrangement of linearly polarized laser waves of nonrelativistic intensity. An incident electron beam is first coherently scattered off a bichromatic laser field, splitting the beam into two portions, with electron spin and momentum being entangled. Afterwards, the partial beams are coherently superposed in an interferometric setup formed by standing laser waves. As a result, the outgoing electron beam is separated into its spin components along the laser magnetic field, which is shown by both analytical and numerical solutions of Pauli's equation. The proposed laser field configuration thus exerts the same effect on free electrons as an ordinary Stern-Gerlach magnet does on atoms.

  13. Spin-Polarizing Interferometric Beam Splitter for Free Electrons

    NASA Astrophysics Data System (ADS)

    Dellweg, Matthias M.; Müller, Carsten

    2017-02-01

    A spin-polarizing electron beam splitter is described that relies on an arrangement of linearly polarized laser waves of nonrelativistic intensity. An incident electron beam is first coherently scattered off a bichromatic laser field, splitting the beam into two portions, with electron spin and momentum being entangled. Afterwards, the partial beams are coherently superposed in an interferometric setup formed by standing laser waves. As a result, the outgoing electron beam is separated into its spin components along the laser magnetic field, which is shown by both analytical and numerical solutions of Pauli's equation. The proposed laser field configuration thus exerts the same effect on free electrons as an ordinary Stern-Gerlach magnet does on atoms.

  14. Space charge corrected electron emission from an aluminum surface under non-equilibrium conditions

    SciTech Connect

    Wendelen, W.; Bogaerts, A.; Mueller, B. Y.; Rethfeld, B.; Autrique, D.

    2012-06-01

    A theoretical study has been conducted of ultrashort pulsed laser induced electron emission from an aluminum surface. Electron emission fluxes retrieved from the commonly employed Fowler-DuBridge theory were compared to fluxes based on a laser-induced non-equilibrium electron distribution. As a result, the two- and three-photon photoelectron emission parameters for the Fowler-DuBridge theory have been approximated. We observe that at regimes where photoemission is important, laser-induced electron emission evolves in a more smooth manner than predicted by the Fowler-DuBridge theory. The importance of the actual electron distribution decreases at higher laser fluences, whereas the contribution of thermionic emission increases. Furthermore, the influence of a space charge effect on electron emission was evaluated by a one dimensional particle-in-cell model. Depending on the fluences, the space charge reduces the electron emission by several orders of magnitude. The influence of the electron emission flux profiles on the effective electron emission was found to be negligible. However, a non-equilibrium electron velocity distribution increases the effective electron emission significantly. Our results show that it is essential to consider the non-equilibrium electron distribution as well as the space charge effect for the description of laser-induced photoemission.

  15. Electron beam characterization of a combined diode rf electron gun

    NASA Astrophysics Data System (ADS)

    Ganter, R.; Beutner, B.; Binder, S.; Braun, H. H.; Garvey, T.; Gough, C.; Hauri, C.; Ischebeck, R.; Ivkovic, S.; Le Pimpec, F.; Li, K.; Paraliev, M. L.; Pedrozzi, M.; Schietinger, T.; Steffen, B.; Trisorio, A.; Wrulich, A.

    2010-09-01

    Experimental and simulation results of an electron gun test facility, based on pulsed diode acceleration followed by a two-cell rf cavity at 1.5 GHz, are presented here. The main features of this diode-rf combination are: a high peak gradient in the diode (up to 100MV/m) obtained without breakdown conditioning, a cathode shape providing an electrostatic focusing, and an in-vacuum pulsed solenoid to focus the electron beam between the diode and the rf cavity. Although the test stand was initially developed for testing field emitter arrays cathodes, it became also interesting to explore the limits of this electron gun with metallic photocathodes illuminated by laser pulses. The ultimate goal of this test facility is to fulfill the requirements of the SwissFEL project of Paul Scherrer Institute [B. D. Patterson , New J. Phys. 12, 035012 (2010)NJOPFM1367-263010.1088/1367-2630/12/3/035012]; a projected normalized emittance below 0.4μm for a charge of 200 pC and a bunch length of less than 10 ps (rms). A normalized projected emittance of 0.23μm with 13 pC has been measured at 5 MeV using a Gaussian laser longitudinal intensity distribution on the photocathode. Good agreements with simulations have been obtained for different electron bunch charge and diode geometries. Emittance measurements at a bunch charge below 1 pC were performed for different laser spot sizes in agreement with intrinsic emittance theory [e.g. 0.54μm/mm of laser spot size (rms) for Cu at 274 nm]. Finally, a projected emittance of 1.25+/-0.2μm was measured with 200 pC and 100MV/m diode gradient.

  16. Simulating Electron Cloud Effects in Heavy-Ion Beams

    SciTech Connect

    Cohen, R.H.; Friedman, A.; Lund, S.W.; Molvik, A.W.; Azevedo, T.; Vay, J.-L.; Stoltz, P.; Veitzer, S.

    2004-08-04

    Stray electrons can be introduced in heavy ion fusion accelerators as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary-electron emission. We summarize here results from several studies of electron-cloud accumulation and effects: (1) Calculation of the electron cloud produced by electron desorption from computed beam ion loss; the importance of ion scattering is shown; (2) Simulation of the effect of specified electron cloud distributions on ion beam dynamics. We find electron cloud variations that are resonant with the breathing mode of the beam have the biggest impact on the beam (larger than other resonant and random variations), and that the ion beam is surprisingly robust, with an electron density several percent of the beam density required to produce significant beam degradation in a 200-quadrupole system. We identify a possible instability associated with desorption and resonance with the breathing mode. (3) Preliminary investigations of a long-timestep algorithm for electron dynamics in arbitrary magnetic fields.

  17. Optimization of combined electron and photon beams for breast cancer

    NASA Astrophysics Data System (ADS)

    Xiong, W.; Li, J.; Chen, L.; Price, R. A.; Freedman, G.; Ding, M.; Qin, L.; Yang, J.; Ma, C.-M.

    2004-05-01

    Recently, intensity-modulated radiation therapy and modulated electron radiotherapy have gathered a growing interest for the treatment of breast and head and neck tumours. In this work, we carried out a study to combine electron and photon beams to achieve differential dose distributions for multiple target volumes simultaneously. A Monte Carlo based treatment planning system was investigated, which consists of a set of software tools to perform accurate dose calculation, treatment optimization, leaf sequencing and plan analysis. We compared breast treatment plans generated using this home-grown optimization and dose calculation software for different treatment techniques. Five different planning techniques have been developed for this study based on a standard photon beam whole breast treatment and an electron beam tumour bed cone down. Technique 1 includes two 6 MV tangential wedged photon beams followed by an anterior boost electron field. Technique 2 includes two 6 MV tangential intensity-modulated photon beams and the same boost electron field. Technique 3 optimizes two intensity-modulated photon beams based on a boost electron field. Technique 4 optimizes two intensity-modulated photon beams and the weight of the boost electron field. Technique 5 combines two intensity-modulated photon beams with an intensity-modulated electron field. Our results show that technique 2 can reduce hot spots both in the breast and the tumour bed compared to technique 1 (dose inhomogeneity is reduced from 34% to 28% for the target). Techniques 3, 4 and 5 can deliver a more homogeneous dose distribution to the target (with dose inhomogeneities for the target of 22%, 20% and 9%, respectively). In many cases techniques 3, 4 and 5 can reduce the dose to the lung and heart. It is concluded that combined photon and electron beam therapy may be advantageous for treating breast cancer compared to conventional treatment techniques using tangential wedged photon beams followed by a boost

  18. Onorbit electron beam welding experiment definition

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The proposed experiment design calls for six panels to be welded, each having unique characteristics selected to yield specific results and information. The experiment is completely automated and the concept necessitated the design of a new, miniaturized, self-contained electron beam (EB) welding system, for which purpose a separate IR and D was funded by the contractor, Martin Marietta Corporation. Since future tasks beyond the proposed experiment might call for astronauts to perform hand-held EB gun repairs or for the gun to be interfaced with a dexterous robot such as the planned flight telerobotic servicer (FTS), the EB gun is designed to be dismountable from the automated system. In the experiment design, two separate, identical sets of weld panels will be welded, one on earth in a vacuum chamber and the other onorbit in the aft cargo bay of an orbiter. Since the main objective of the experiment is to demonstrate that high quality welds can be achieved under onorbit conditions, the welds produced will be subjected to a wide range of discriminating non-destructive Q.C. procedures and destructive physical tests. However, advantage will be taken of the availability of a fairly large quantity of welded material in the two series of welded specimens to widen the circle of investigative talent by providing material to academic and scientific institutions for examination.

  19. Heat shrinkage of electron beam modified EVA

    NASA Astrophysics Data System (ADS)

    Datta, Sujit K.; Chaki, T. K.; Tikku, V. K.; Pradhan, N. K.; Bhowmick, A. K.

    1997-10-01

    Heat shrinkage of electron beam modified ethylene vinyl acetate copolymer (EVA) has been investigated over a range of times, temperatures, stretching, irradiation doses and trimethylolpropane trimethacrylate (TMPTMA) levels. The irradiated (radiation dose 50 kGy and TMPTMA level 1%) and stretched (100% elongation) sample shrinks to a maximum level when kept at 453K temperature for 60 s. The heat shrinkage of samples irradiated with radiation doses of 20, 50, 100 and 150 kGy increases sharply with increasing stretching in the initial stage. Amnesia rating decreases with increasing radiation dose and TMPTMA level as well as gel content. The high radiation dose and TMPTMA level lower the heat shrinkage due to the chain scission. The effect of temperature at which extension is carried out on heat shrinkage is marginal. The irradiated (radiation dose 50 kGy and TMPTMA level 1%) EVA tubes of different dimensions expanded in a laboratory grade tube expander show similar behaviour at 453K and 60 s. The X-ray and DSC studies reveal that the crystallinity increases on stretching due to orientation of chains and it decreases to a considerable extent on heat shrinking. The theoretical and experimental values of heat shrinkage for tubes and rectangular strips are in good accord, when the radiation dose is 50 kGy and TMPTMA level 1%.

  20. Transverse profile of the electron beam for the RHIC electron lenses

    NASA Astrophysics Data System (ADS)

    Gu, X.; Altinbas, Z.; Costanzo, M.; Fischer, W.; Gassner, D. M.; Hock, J.; Luo, Y.; Miller, T.; Tan, Y.; Thieberger, P.; Montag, C.; Pikin, A. I.

    2015-10-01

    The transverse profile of the electron beam plays a very important role in assuring the success of the electron lens beam-beam compensation, as well as its application in space charge compensation. To compensate for the beam-beam effect in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, we recently installed and commissioned two electron lenses. In this paper, we describe, via theory and simulations using the code Parmela, the evolution of the density of the electron beam with space charge within an electron lens from the gun to the main solenoid. Our theoretical analysis shows that the change in the beam transverse density is dominated by the effects of the space charge induced longitudinal velocity reduction, not by those of transverse Coulomb collisions. We detail the transverse profile of RHIC electron-lens beam, measured via the YAG screen and pinhole detector, and also describe its profile that we assessed from the signal of the electron-backscatter detector (eBSD) via scanning the electron beam with respect to the RHIC beam. We verified, in simulations and experiments, that the distribution of the transverse electron beam is Gaussian throughout its propagation in the RHIC electron lens.

  1. IBS in a CAM-Dominated Electron Beam

    SciTech Connect

    Burov, A.; Nagaitsev, S.; Shemyakin, A.; Gusachenko, I.

    2006-03-20

    Electron cooling of the 8.9 GeV/c antiprotons in the Recycler ring requires high-quality dc electron beam with the current of several hundred mA and the kinetic energy of 4.3 MeV. That high electron current is attained through beam recirculation (charge recovery). The primary current path is from the magnetized cathode at high voltage terminal to the ground, where the electron beam interacts with the antiproton beam and cooling takes place, and then to the collector in the terminal. The energy distribution function of the electron beam at the collector determines the required collector energy acceptance. Multiple and single intra-beam scattering as well as the dissipation of density micro-fluctuations during the beam transport are studied as factors forming a core and tails of the electron energy distribution. For parameters of the Fermilab electron cooler, the single intra-beam scattering (Touschek effect) is found to be of the most importance.

  2. Experimental observation of helical microbunching of a relativistic electron beam

    SciTech Connect

    Hemsing, E.; Knyazik, A.; O'Shea, F.; Marinelli, A.; Musumeci, P.; Williams, O.; Rosenzweig, J. B.; Tochitsky, S.

    2012-02-27

    Experimental observation of the microbunching of a relativistic electron beam at the second harmonic interaction frequency of a helical undulator is presented. The microbunching signal is observed from the coherent transition radiation of the electron beam and indicates experimental evidence of a dominantly helical electron beam density distribution. This result is in agreement with theoretical and numerical predictions and provides a proof-of-principle demonstration of proposed schemes designed to generate light with orbital angular momentum in high-gain free-electron lasers.

  3. A simple model of electron beam initiated dielectric breakdown

    NASA Technical Reports Server (NTRS)

    Beers, B. L.; Daniell, R. E.; Delmer, T. N.

    1985-01-01

    A steady state model that describes the internal charge distribution of a planar dielectric sample exposed to a uniform electron beam was developed. The model includes the effects of charge deposition and ionization of the beam, separate trap-modulated mobilities for electrons and holes, electron-hole recombination, and pair production by drifting thermal electrons. If the incident beam current is greater than a certain critical value (which depends on sample thickness as well as other sample properties), the steady state solution is non-physical.

  4. Production and dosimetry of simultaneous therapeutic photons and electrons beam by linear accelerator: A Monte Carlo study

    SciTech Connect

    Khledi, Navid; Sardari, Dariush; Arbabi, Azim; Ameri, Ahmad; Mohammadi, Mohammad

    2015-02-24

    Depending on the location and depth of tumor, the electron or photon beams might be used for treatment. Electron beam have some advantages over photon beam for treatment of shallow tumors to spare the normal tissues beyond of the tumor. In the other hand, the photon beam are used for deep targets treatment. Both of these beams have some limitations, for example the dependency of penumbra with depth, and the lack of lateral equilibrium for small electron beam fields. In first, we simulated the conventional head configuration of Varian 2300 for 16 MeV electron, and the results approved by benchmarking the Percent Depth Dose (PDD) and profile of the simulation and measurement. In the next step, a perforated Lead (Pb) sheet with 1mm thickness placed at the top of the applicator holder tray. This layer producing bremsstrahlung x-ray and a part of the electrons passing through the holes, in result, we have a simultaneous mixed electron and photon beam. For making the irradiation field uniform, a layer of steel placed after the Pb layer. The simulation was performed for 10×10, and 4×4 cm2 field size. This study was showed the advantages of mixing the electron and photon beam by reduction of pure electron's penumbra dependency with the depth, especially for small fields, also decreasing of dramatic changes of PDD curve with irradiation field size.

  5. Non-equilibrium vibrational and electron energy distribution functions in mtorr, high-electron-density nitrogen discharges and afterglows

    NASA Astrophysics Data System (ADS)

    Capitelli, M.; Colonna, G.; D’Ammando, G.; Laricchiuta, A.; Pietanza, L. D.

    2017-03-01

    Non-equilibrium vibrational distributions (vdf) and non-equilibrium electron energy distribution functions (eedf) in a nitrogen plasma at low pressure (mtorr) have been calculated by using a time-dependent plasma physics model coupled to the Boltzmann equation and heavy particle kinetics. Different case studies have been selected showing the non-equilibrium character of both vdf and eedf under discharge and post-discharge conditions in the presence of large concentrations of electrons. Particular attention is devoted to the electron-molecule resonant vibrational excitation cross sections acting in the whole vibrational ladder. The results in the post-discharge conditions show the interplay of superelastic vibrational and electronic collisions in forming structures in the eedf. The link between the present results in the mtorr afterglow regime with the existing eedf in the torr and atmospheric regimes is discussed.

  6. Electron Cyclotron Maser Emissions from Evolving Fast Electron Beams

    NASA Astrophysics Data System (ADS)

    Tang, J. F.; Wu, D. J.; Chen, L.; Zhao, G. Q.; Tan, C. M.

    2016-05-01

    Fast electron beams (FEBs) are common products of solar active phenomena. Solar radio bursts are an important diagnostic tool for understanding FEBs and the solar plasma environment in which they propagate along solar magnetic fields. In particular, the evolution of the energy spectrum and velocity distribution of FEBs due to the interaction with the ambient plasma and field during propagation can significantly influence the efficiency and properties of their emissions. In this paper, we discuss the possible evolution of the energy spectrum and velocity distribution of FEBs due to energy loss processes and the pitch-angle effect caused by magnetic field inhomogeneity, and we analyze the effects of the evolution on electron-cyclotron maser (ECM) emission, which is one of the most important mechanisms for producing solar radio bursts by FEBs. Our results show that the growth rates all decrease with the energy loss factor Q, but increase with the magnetic mirror ratio σ as well as with the steepness index δ. Moreover, the evolution of FEBs can also significantly influence the fastest growing mode and the fastest growing phase angle. This leads to the change of the polarization sense of the ECM emission. In particular, our results also reveal that an FEB that undergoes different evolution processes will generate different types of ECM emission. We believe the present results to be very helpful for a more comprehensive understanding of the dynamic spectra of solar radio bursts.

  7. Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

    PubMed Central

    Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

    2012-01-01

    Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process. PMID:23242276

  8. Plasma charge current for controlling and monitoring electron beam welding with beam oscillation.

    PubMed

    Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

    2012-12-14

    Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process.

  9. Virtual mask digital electron beam lithography

    DOEpatents

    Baylor, Larry R.; Thomas, Clarence E.; Voelkl, Edgar; Moore, James A.; Simpson, Michael L.; Paulus, Michael J.

    1999-01-01

    Systems and methods for direct-to-digital holography are described. An apparatus includes a laser; a beamsplitter optically coupled to the laser; a reference beam mirror optically coupled to the beamsplitter; an object optically coupled to the beamsplitter, a focusing lens optically coupled to both the reference beam mirror and the object; and a digital recorder optically coupled to the focusing lens. A reference beam is incident upon the reference beam mirror at a non-normal angle, and the reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form an image. The systems and methods provide advantages in that computer assisted holographic measurements can be made.

  10. Virtual mask digital electron beam lithography

    DOEpatents

    Baylor, L.R.; Thomas, C.E.; Voelkl, E.; Moore, J.A.; Simpson, M.L.; Paulus, M.J.

    1999-04-06

    Systems and methods for direct-to-digital holography are described. An apparatus includes a laser; a beamsplitter optically coupled to the laser; a reference beam mirror optically coupled to the beamsplitter; an object optically coupled to the beamsplitter, a focusing lens optically coupled to both the reference beam mirror and the object; and a digital recorder optically coupled to the focusing lens. A reference beam is incident upon the reference beam mirror at a non-normal angle, and the reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form an image. The systems and methods provide advantages in that computer assisted holographic measurements can be made. 5 figs.

  11. Interfacial Properties of Electron Beam Cured Composites

    SciTech Connect

    Eberle, C.C.

    1999-12-30

    The objectives of the CRADA are to: Confirm that fiber-resin adhesion is responsible for the observed poor shear properties; Determine the mechanism(s) responsible for poor adhesion between carbon fibers and epoxy resins after e-beam curing; Develop and evaluate resin systems and fiber treatments to improve the properties of e-beam cured, carbon-fiber-reinforced composites; and Develop refined methods for processing e-beam cured, carbon-fiber-reinforced composites.

  12. Fast wire scanner for intense electron beams

    NASA Astrophysics Data System (ADS)

    Moore, T.; Agladze, N. I.; Bazarov, I. V.; Bartnik, A.; Dobbins, J.; Dunham, B.; Full, S.; Li, Y.; Liu, X.; Savino, J.; Smolenski, K.

    2014-02-01

    We have developed a cost-effective, fast rotating wire scanner for use in accelerators where high beam currents would otherwise melt even carbon wires. This new design uses a simple planetary gear setup to rotate a carbon wire, fixed at one end, through the beam at speeds in excess of 20 m/s. We present results from bench tests, as well as transverse beam profile measurements taken at Cornell's high-brightness energy recovery linac photoinjector, for beam currents up to 35 mA.

  13. Dense plasma heating by crossing relativistic electron beams

    NASA Astrophysics Data System (ADS)

    Ratan, N.; Sircombe, N. J.; Ceurvorst, L.; Sadler, J.; Kasim, M. F.; Holloway, J.; Levy, M. C.; Trines, R.; Bingham, R.; Norreys, P. A.

    2017-01-01

    Here we investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams. Heating occurs as an instability of the electron beams drives Langmuir waves, which couple nonlinearly into damped ion-acoustic waves. Simulations show a factor 2.8 increase in electron kinetic energy with a coupling efficiency of 18%. Our results support applications to the production of warm dense matter and as a driver for inertial fusion plasmas.

  14. Dense plasma heating by crossing relativistic electron beams.

    PubMed

    Ratan, N; Sircombe, N J; Ceurvorst, L; Sadler, J; Kasim, M F; Holloway, J; Levy, M C; Trines, R; Bingham, R; Norreys, P A

    2017-01-01

    Here we investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams. Heating occurs as an instability of the electron beams drives Langmuir waves, which couple nonlinearly into damped ion-acoustic waves. Simulations show a factor 2.8 increase in electron kinetic energy with a coupling efficiency of 18%. Our results support applications to the production of warm dense matter and as a driver for inertial fusion plasmas.

  15. Limiting current of intense electron beams in a decelerating gap

    NASA Astrophysics Data System (ADS)

    Nusinovich, G. S.; Beaudoin, B. L.; Thompson, C.; Karakkad, J. A.; Antonsen, T. M.

    2016-02-01

    For numerous applications, it is desirable to develop electron beam driven efficient sources of electromagnetic radiation that are capable of producing the required power at beam voltages as low as possible. This trend is limited by space charge effects that cause the reduction of electron kinetic energy and can lead to electron reflection. So far, this effect was analyzed for intense beams propagating in uniform metallic pipes. In the present study, the limiting currents of intense electron beams are analyzed for the case of beam propagation in the tubes with gaps. A general treatment is illustrated by an example evaluating the limiting current in a high-power, tunable 1-10 MHz inductive output tube (IOT), which is currently under development for ionospheric modification. Results of the analytical theory are compared to results of numerical simulations. The results obtained allow one to estimate the interaction efficiency of IOTs.

  16. Applications with Intense OTR Images II: Microbunched Electron Beams

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Dejus, R. J.; Rule, D. W.

    2004-12-01

    In this second application for intense images we take advantage of the coherent enhancement of optical transition radiation (OTR) due to self-amplified spontaneous emission (SASE) free-electron laser (FEL)-induced microbunching of the beam. A much smaller number of total particles is involved, but the microbunched fraction (NB) gives a NB2 enhancement. We report measurements on the z-dependent growth of the coherent OTR (COTR) and the effects of beam size and electron beam/photon beam coalignment in the COTR interferograms.

  17. Tracking on the joint during the electron beam welding

    NASA Astrophysics Data System (ADS)

    Braverman, V.; Bogdanov, V.; Belozertsev, V.; Uspenskiy, N.

    2016-11-01

    In the article the description of device, which provides automatic positioning of electron beam relative to joint of welded parts during welding, is given. Extremum seeking based on synchronous detection of sensor signal (X-ray or secondary emission) is realized in the device. Measurements are made when beam goes out of the channel following the welding direction. The application of synchronous detection is possible due to the fact that during joint scanning with electron beam harmonics, carrying data about beam position relative to the joint appear in the joint sensor signal spectrum.

  18. Application of optical beams to electrons in graphene

    SciTech Connect

    Matulis, A.; Masir, M. Ramezani; Peeters, F. M.

    2011-03-15

    The technique of beam optics is applied to the description of the wave function of Dirac electrons. This approach is illustrated by considering electron transmission through simple nonhomogeneous structures, such as flat and bent p-n junctions and superlattices. We found that a convex p-n junction compresses the beam waist, while a concave interface widens it without loosing its focusing properties. At a flat p-n junction the waist of the transmitted Gaussian beam can be narrowed or widened, depending on the angle of incidence. A general condition is derived for the occurrence of beam collimation in a superlattice which is less stringent than previous discussed.

  19. Beam-induced electron modulations observed during TSS 1R

    NASA Astrophysics Data System (ADS)

    Rubin, A. G.; Burke, W. J.; Gough, M. P.; Machuzak, J. S.; Gentile, L. C.; Huang, C. Y.; Hardy, D. A.; Thompson, D. C.; Raitt, W. J.

    1999-08-01

    We report on modulations of electron fluxes at megahertz frequencies measured by the Shuttle Potential and Return Electron Experiment (SPREE) during fast pulsed electron gun (FPEG) beam experiments conducted after the tether break event of the Tethered Satellite System Reflight. Six intervals of sustained modulations were identified while FPEG emitted a 100 mA beam of 1 kev electrons. During five events the beam pitch angle αB was near 90° and the modulations were near even or odd half harmonics of the electron gyrofrequency fce. In the sixth event with 60°>=αB>=45°, electron modulations were near estimated values of the electron plasma frequency fpe and 2fpe. Whenever SPREE detected beam electrons modulated at a given frequency, secondary electrons were also modulated at the same frequency over a broad range of energies. Occasionally, some secondary electrons were modulated simultaneously at a second frequency. Multiple frequencies were related as ratios of low integers. In one case the beam electrons were simultaneously modulated at 0.8 MHz and 1.25 kHz. SPREE measurements suggest that the beam electrons propagate in cylindrical shells whose inner edge is marked by steep spatial gradients in fluxes at 1 keV [Hardy et al., 1995]. Inside the shell, electron distribution functions have positive slopes ∂f/∂v⊥>0 at velocities near that of the beam. Velocity space gradients act as free-energy sources to drive cavity modes that alter the instantaneous guiding centers of electrons causing SPREE to sample alternating parts of the beam cylinder's inner edge. Associated time-varying electric fields also modulated the fluxes of secondary electrons reaching SPREE. Other cavity modes may be excited through nonlinear processes [Calvert, 1982]. With αB far from 90°, electrons in the beam cylinder evolved toward bump-on-tail distributions to excite large-amplitude Langmuir modulations at fpe and its harmonics [Klimas, 1983]. Low-frequency modulations are attributed

  20. The Moving Lines on Electron Spectra as Charge Reflexes on Non-equilibrium States of Nanostructured Surfaces

    NASA Astrophysics Data System (ADS)

    Mishchuk, Oleg A.

    2016-04-01

    The experimental results present the phenomenon of moving lines on electron spectra which are linked spatially and in time with the localization and durability of the processes of new surface producing in folds and grain boundaries. This effect was also realized for a thin-layer composite "organic on metal films on dielectric substrate" in modeling non-equilibrium conditions which are created by the intensive electron beam pulse impact. It was found that the nature of the inceptive adsorption layer, in addition to the metal film, determines the initial positions of moving lines on the spectra. The main accents in these investigations were in observations of appearance of the moving lines, dynamics of their displacements on the spectra, final stages when these lines vanished, and finding the general regularities between the spontaneous and induced events.

  1. The Moving Lines on Electron Spectra as Charge Reflexes on Non-equilibrium States of Nanostructured Surfaces.

    PubMed

    Mishchuk, Oleg A

    2016-12-01

    The experimental results present the phenomenon of moving lines on electron spectra which are linked spatially and in time with the localization and durability of the processes of new surface producing in folds and grain boundaries. This effect was also realized for a thin-layer composite "organic on metal films on dielectric substrate" in modeling non-equilibrium conditions which are created by the intensive electron beam pulse impact. It was found that the nature of the inceptive adsorption layer, in addition to the metal film, determines the initial positions of moving lines on the spectra. The main accents in these investigations were in observations of appearance of the moving lines, dynamics of their displacements on the spectra, final stages when these lines vanished, and finding the general regularities between the spontaneous and induced events.

  2. EFFECT OF SOLENOID FIELD ERRORS ON ELECTRON BEAM TEMPERATURES IN THE RHIC ELECTRON COOLER.

    SciTech Connect

    MONTAG,C.KEWISCH,J.

    2003-05-12

    As part of a future upgrade to the Relativistic Heavy Ion Collider (RHIC), electron cooling is foreseen to decrease ion beam emittances. Within the electron cooling section, the ''hot'' ion beam is immersed in a ''cold'' electron beam. The cooling effect is further enhanced by a solenoid field in the cooling section, which forces the electrons to spiral around the field lines with a (Larmor) radius of 10 micrometers, reducing the effective transverse temperature by orders of magnitude. Studies of the effect of solenoid field errors on electron beam temperatures are reported.

  3. Miniature electron microscope beam column optics

    NASA Astrophysics Data System (ADS)

    Loyd, Jody Stuart

    This investigation is in the area of electrostatic lens design with the overarching goal of contributing to the creation of a miniaturized scanning electron microscope (SEM) for use in mineralogical analysis or detection of signs of life on the surface of Mars. Such an instrument could also have application in the exploration of Earth's moon, planetary moons, asteroids, or comets. Other embodiments could include tabletop or field portable SEMs for use on Earth. The scope of this research is in the design of a beam column that attains focusing, demagnification, and aberration control within the smallest achievable package. The goals of planetary exploration and of spaceflight in general impose severe constraints on the instrument's mass and electrical power consumption, while favoring a robust design of small size and high rigidity that is also simple to align. To meet these requirements a design using electrostatic lenses was favored because of the lower power requirement and mass of electrostatic versus magnetic lenses, their relatively simple construction, as well as inherently easier shielding from extraneous fields. In modeling the lens field, a hybrid of a Boundary Element Method (BEM) and a Fourier series solution was employed, whereby an initial solution from the BEM is used to derive the bounding potential of a cylindrical subdomain for the subsequent Fourier series solution. The approach is applicable to many problems in physics and combines the inherent precision of this series solution with the flexibility of BEM to describe practical, non-idealized electrode shapes. The resulting lens field in the Fourier series subdomain is of higher precision, thereby allowing smaller errors in subsequent calculations of electron ray paths. The effects of aberrations are thus easier to observe in tracing non-paraxial rays. A significant speed increase in tracing rays is also observed. The modeling technique has been validated by reproducing example ray-traces through

  4. Focused ion beam scanning electron microscopy in biology.

    PubMed

    Kizilyaprak, C; Daraspe, J; Humbel, B M

    2014-06-01

    Since the end of the last millennium, the focused ion beam scanning electron microscopy (FIB-SEM) has progressively found use in biological research. This instrument is a scanning electron microscope (SEM) with an attached gallium ion column and the 2 beams, electrons and ions (FIB) are focused on one coincident point. The main application is the acquisition of three-dimensional data, FIB-SEM tomography. With the ion beam, some nanometres of the surface are removed and the remaining block-face is imaged with the electron beam in a repetitive manner. The instrument can also be used to cut open biological structures to get access to internal structures or to prepare thin lamella for imaging by (cryo-) transmission electron microscopy. Here, we will present an overview of the development of FIB-SEM and discuss a few points about sample preparation and imaging.

  5. An Electron-Beam Profile Monitor Using Fresnel Zone Plates

    SciTech Connect

    Nakamura, Norio; Sakai, Hiroshi; Iida, Kensuke; Shinoe, Kenji; Takaki, Hiroyuki; Fujisawa, Masami; Hayano, Hitoshi; Muto, Toshiya; Nomura, Masaharu; Kamiya, Yukihide; Koseki, Tadashi; Amemiya, Yoshiyuki; Aoki, Nobutada; Nakayama, Koichi

    2004-05-12

    We have developed a beam profile monitor using two Fresnel zone plates (FZPs) at the KEK-ATF (Accelerator Test Facility) damping ring to measure small electron-beam sizes for low-emittance synchrotron radiation sources. The monitor has a structure of an X-ray microscope, where two FZPs constitute an X-ray imaging optics. In the monitor system, the synchrotron radiation from the electron beam at the bending magnet is monochromatized to 3.235-keV X-rays by a crystal monochromator and the transverse electron-beam image is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. This monitor has the following advantages: (1) high spatial resolution, (2) non-destructive measurement, (3) real-time monitoring, and (4) direct electron-beam imaging. With the beam profile monitor, we have succeeded in obtaining a clear electron-beam image and measuring the extremely small beam size less than 10 {mu}m. The measured magnification of the imaging optics was in good agreement with the design value.

  6. Nonlinear longitudinal space charge oscillations in relativistic electron beams.

    PubMed

    Musumeci, P; Li, R K; Marinelli, A

    2011-05-06

    In this Letter we study the evolution of an initial periodic modulation in the temporal profile of a relativistic electron beam under the effect of longitudinal space-charge forces. Linear theory predicts a periodic exchange of the modulation between the density and the energy profiles at the beam plasma frequency. For large enough initial modulations, wave breaking occurs after 1/2 period of plasma oscillation leading to the formation of short current spikes. We confirm this effect by direct measurements on a ps-modulated electron beam from an rf photoinjector. These results are useful for the generation of intense electron pulse trains for advanced accelerator applications.

  7. Nonlinear Longitudinal Space Charge Oscillations in Relativistic Electron Beams

    SciTech Connect

    Musumeci, P.; Li, R. K.; Marinelli, A.

    2011-05-06

    In this Letter we study the evolution of an initial periodic modulation in the temporal profile of a relativistic electron beam under the effect of longitudinal space-charge forces. Linear theory predicts a periodic exchange of the modulation between the density and the energy profiles at the beam plasma frequency. For large enough initial modulations, wave breaking occurs after 1/2 period of plasma oscillation leading to the formation of short current spikes. We confirm this effect by direct measurements on a ps-modulated electron beam from an rf photoinjector. These results are useful for the generation of intense electron pulse trains for advanced accelerator applications.

  8. Economics of electron beam accelerator facilities: Concept vs actual

    NASA Astrophysics Data System (ADS)

    Minbiole, Paul R.

    1995-02-01

    Electron beam accelerator facilities continue to demonstrate their ability to "add value" to a wide range of industrial products. The power, energy, and reliability of commercially available accelerators have increased steadily over the past several decades. The high throughput potential of modern electron beam facilities, together with the broad spectrum of commercial applications, result in the concept that an electron beam facility is an effective tool for adding economic value to industrial products. However, the high capital costs of such a facility (including hidden costs), together with practical limitations to high throughput (including several layers of inefficiencies), result in profit-and-loss economics which are more tenuous than expected after first analysis.

  9. Patterned electrochemical deposition of copper using an electron beam

    SciTech Connect

    Heijer, Mark den; Shao, Ingrid; Reuter, Mark C.; Ross, Frances M.; Radisic, Alex

    2014-02-01

    We describe a technique for patterning clusters of metal using electrochemical deposition. By operating an electrochemical cell in the transmission electron microscope, we deposit Cu on Au under potentiostatic conditions. For acidified copper sulphate electrolytes, nucleation occurs uniformly over the electrode. However, when chloride ions are added there is a range of applied potentials over which nucleation occurs only in areas irradiated by the electron beam. By scanning the beam we control nucleation to form patterns of deposited copper. We discuss the mechanism for this effect in terms of electron beam-induced reactions with copper chloride, and consider possible applications.

  10. Separating the Spin States of a Free Electron Beam

    NASA Astrophysics Data System (ADS)

    Rifkin, Neil

    2008-10-01

    In 1922 Otto Stern and Walther Gerlach set out to test the spacial quantization of the electron by passing a beam of neutral silver atoms through a transverse magnetic field. The interaction of the two projections of the electron's magnetic moment with the magnetic field resulted in a splitting of the beam. However, for some sixty years it was generally accepted that the spin of free electrons, and thus their magnetic moment, could not be measured with an experiment similar to that of Stern and Gerlach. The reason being that the lorentz force on charged particles is far greater than the force due to the magnetic moment of the electron, thus blurring any desired results. To reduce the lorentz force, the electrons could be passed through a magnetic field whose gradient is in the direction of the electrons' momentum. This longitudinal Stern-Gerlach device, with a superconducting magnet, could polarize the tails of a low energy electron beam.

  11. A compact, versatile low-energy electron beam ion source

    SciTech Connect

    Zschornack, G.; König, J.; Schmidt, M.; Thorn, A.

    2014-02-15

    A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

  12. A compact, versatile low-energy electron beam ion source.

    PubMed

    Zschornack, G; König, J; Schmidt, M; Thorn, A

    2014-02-01

    A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

  13. Beam induced electron cloud resonances in dipole magnetic fields

    NASA Astrophysics Data System (ADS)

    Calvey, J. R.; Hartung, W.; Makita, J.; Venturini, M.

    2016-07-01

    The buildup of low energy electrons in an accelerator, known as electron cloud, can be severely detrimental to machine performance. Under certain beam conditions, the beam can become resonant with the cloud dynamics, accelerating the buildup of electrons. This paper will examine two such effects: multipacting resonances, in which the cloud development time is resonant with the bunch spacing, and cyclotron resonances, in which the cyclotron period of electrons in a magnetic field is a multiple of bunch spacing. Both resonances have been studied directly in dipole fields using retarding field analyzers installed in the Cornell Electron Storage Ring. These measurements are supported by both analytical models and computer simulations.

  14. The use of electron beams for pasteurization of meats

    SciTech Connect

    Prestwich, K.R.; Kaye, R.J.; Turman, B.N.; Neau, E.L.

    1994-12-01

    Electron beam accelerators can be used for electronic pasteurization of meat products by: (1) using the electrons directly impacting the products, or (2) optimizing the conversion of electron energy to x-rays and treating the product with these x-rays. The choice of process depends on the configuration of the product when it is treated. For electron treatment, ten million electron volt (MeV) kinetic energy is the maximum allowed by international agreement. The depth of penetration of electrons with that energy into a product with density of meat is about five centimeters (cm). Two-sided treatment can be done on products up to 10 cm thick with a two-to-one ratio between minimum and maximum dose. Ground beef patties are about 1.25 cm (0.5 inch thick). Beams with 2.5 MeV electron energy could be used to treat these products. Our calculations show that maximum to minimum dose ratios less than 1.2 can be achieved with this energy if the transverse beam energy is small. If the product thickness is greater than 10 cm, x-rays can provide the needed dose uniformity. Uniform doses can be supplied for pallets with dimensions greater than 1.2 m on each side using x-rays from a 5 MeV electron beam. The efficiency of converting the electron beam to x-rays and configurations to achieve dose uniformity are discussed.

  15. How an Electron Beam (Eventually) Penetrates Ceramic Cloth

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Russell, C. K.; Zimmerman, F. R.; Fragomeni, J. M.

    1999-01-01

    In anticipation of the International Space Welding Experiment (ISWE) the effect of an electron beam was investigated on Nextel AF-62 ceramic cloth designed to withstand temperatures up to 1427 C. It was anticipated that the cloth would take a static charge that would repel the beam and remain undamaged. It was found that after some seconds the impinging beam penetrated penetrated the cloth. Further, the penetration time went up significantly both at longer and at closer standoff distances. A tentative explanation appears to fit the observed facts. The electrons in the beam generate positive ions by collisions with the contaminant gas molecules in the vacuum chamber. The positive ions transfer a small but significant fraction of the beam power to the cloth. Under the impingement of the positive ions the cloth heats up until sufficient outgassing occurs to initiate arcing. Once arcing occurs the full beam power impinges on the cloth and, almost instantaneously, burns a hole.

  16. Electron gun for a multiple beam klystron with magnetic compression of the electron beams

    DOEpatents

    Ives, R. Lawrence; Tran, Hien T; Bui, Thuc; Attarian, Adam; Tallis, William; David, John; Forstall, Virginia; Andujar, Cynthia; Blach, Noah T; Brown, David B; Gadson, Sean E; Kiley, Erin M; Read, Michael

    2013-10-01

    A multi-beam electron gun provides a plurality N of cathode assemblies comprising a cathode, anode, and focus electrode, each cathode assembly having a local cathode axis and also a central cathode point defined by the intersection of the local cathode axis with the emitting surface of the cathode. Each cathode is arranged with its central point positioned in a plane orthogonal to a device central axis, with each cathode central point an equal distance from the device axis and with an included angle of 360/N between each cathode central point. The local axis of each cathode has a cathode divergence angle with respect to the central axis which is set such that the diverging magnetic field from a solenoidal coil is less than 5 degrees with respect to the projection of the local cathode axis onto a cathode reference plane formed by the device axis and the central cathode point, and the local axis of each cathode is also set such that the angle formed between the cathode reference plane and the local cathode axis results in minimum spiraling in the path of the electron beams in a homogenous magnetic field region of the solenoidal field generator.

  17. Electron beam injection experiments - Replication of flight observations in a laboratory beam plasma discharge

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Mcgarity, J. O.; Konradi, A.

    1983-01-01

    Recent electron beam injection experiments in the lower ionosphere have produced two perplexing results: (1) At altitudes from 140 km to 220 km, the beam associated 391.4 nm intensity is relatively independent of altitude despite the decreasing N2 abundance. (2) The radial extent of the perturbed region populated by beam associated energetic electrons significantly exceeds the nominal gyrodiameter for 90 deg injection. A series of laboratory measurements is described in which both of these flight results appear to have been closely reproduced. The laboratory results are reasonably consistent with the transition from a collision dominated to collisionless beam-plasma discharge configuration.

  18. Advanced accelerating structures and their interaction with electron beams.

    SciTech Connect

    Gai, W.; High Energy Physics

    2008-01-01

    In this paper, we give a brief description of several advanced accelerating structures, such as dielectric loaded waveguides, photonic band gap, metamaterials and improved iris-loaded cavities. We describe wakefields generated by passing high current electron beams through these structures, and applications of wakefields to advanced accelerator schemes. One of the keys to success for high gradient wakefield acceleration is to develop high current drive beam sources. As an example, the high current RF photo injector at the Argonne Wakefield Accelerator, passed a {approx}80 nC electron beam through a high gradient dielectric loaded structure to achieve a 100 MV/m gradient. We will summarize recent related experiments on beam-structure interactions and also discuss high current electron beam generation and propagation and their applications to wakefield acceleration.

  19. Advanced Accelerating Structures and Their Interaction with Electron Beams

    SciTech Connect

    Gai Wei

    2009-01-22

    In this paper, we give a brief description of several advanced accelerating structures, such as dielectric loaded waveguides, photonic band gap, metamaterials and improved iris-loaded cavities. We describe wakefields generated by passing high current electron beams through these structures, and applications of wakefields to advanced accelerator schemes. One of the keys to success for high gradient wakefield acceleration is to develop high current drive beam sources. As an example, the high current RF photo injector at the Argonne Wakefield Accelerator, passed a {approx}80 nC electron beam through a high gradient dielectric loaded structure to achieve a 100 MV/m gradient. We will summarize recent related experiments on beam-structure interactions and also discuss high current electron beam generation and propagation and their applications to wakefield acceleration.

  20. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  1. Double deflection system for an electron beam device

    DOEpatents

    Parker, Norman W.; Golladay, Steven D.; Crewe, Albert V.

    1978-01-01

    A double deflection scanning system for electron beam instruments is provided embodying a means of correcting isotropic coma, and anisotropic coma aberrations induced by the magnetic lens of such an instrument. The scanning system deflects the beam prior to entry into the magnetic lens from the normal on-axis intersection of the beam with the lens according to predetermined formulas and thereby reduces the aberrations.

  2. Collective microdynamics and noise suppression in dispersive electron beam transport

    SciTech Connect

    Gover, Avraham; Dyunin, Egor; Duchovni, Tamir; Nause, Ariel

    2011-12-15

    A general formulation is presented for deep collective interaction micro-dynamics in dispersive e-beam transport. In the regime of transversely coherent interaction, the formulation is applicable to both coherent and random temporal modulation of the electron beam. We demonstrate its use for determining the conditions for suppressing beam current noise below the classical shot-noise level by means of transport through a dispersive section with a small momentum compaction parameter.

  3. Pulsed Electric Discharge Laser Technology. Electron Beam Window Foil Material.

    DTIC Science & Technology

    1984-01-01

    6.0 INTERFEROMETRIC MEASUREMENT OF FOIL MOVEMENT A simple Michelson interferometer was used to measure foil movement on the test rig. Because the...TURNING BEAM MIRRORS BEAM DISPLAYFOCUEED IRIS AT FOOS. OPTICAL FIBRE * BUNDLE Figure 49. Schematic of interferometer . -98-7 reflected speckle. The...As a check on the pulse simulation, the actual movement of an electron-beam foil window was measured by interferometry. A speckle interferometer which

  4. Structured electron beams from nano-engineered cathodes

    NASA Astrophysics Data System (ADS)

    Lueangaramwong, A.; Mihalcea, D.; Andonian, G.; Piot, P.

    2017-03-01

    The ability to engineer cathodes at the nano-scale have opened new possibilities such as enhancing quantum efficiency via surface-plasmon excitation, forming ultra-low-emittance beams, or producing structured electron beams. In this paper, we present numerical investigations of the beam dynamics associated with this class of cathode in the weak- and strong-field regimes. We finally discuss the possible applications of some of the achievable cathode patterns when coupled with other phase space manipulations.

  5. Beam-Beam Study on the Upgrade of Beijing Electron Positron Collider

    SciTech Connect

    Wang, S.; Cai, Y.; /SLAC

    2006-02-10

    It is an important issue to study the beam-beam interaction in the design and performance of such a high luminosity collider as BEPCII, the upgrade of Beijing Electron Positron Collider. The weak-strong simulation is generally used during the design of a collider. For performance a large scale tune scan, the weak-strong simulation studies on beam-beam interaction were done, and the geometry effects were taken into account. The strong-strong simulation studies were done for investigating the luminosity goal and the dependence of the luminosity on the beam parameters.

  6. Prebunched-beam free electron maser

    NASA Astrophysics Data System (ADS)

    Arbel, M.; Ben-Chaim, D.; Cohen, M.; Draznin, M.; Eichenbaum, A.; Gover, Abraham; Kleinman, H.; Kugel, A.; Pinhasi, Yosef; Witman, S.; Yakover, Y. M.

    1994-05-01

    The development status of a prebunched FEM is described. We are developing a 70 KeV FEM to allow high gain wideband operation and to enable variation of the degree of prebunching. We intend to investigate its operation as an amplifier and as an oscillator. Effects of prebunching, frequency variation, linear and nonlinear effects, will be investigated. The prebuncher consists of a Pierce e-gun followed by a beam modulating section. The prebunched beam is accelerated to 70 KeV and injected into a planar wiggler containing a waveguide. The results obtained to date will be presented. These include: characterization of the e-gun, e-beam transport to and through the wiggler, use of field modifying permanent magnets near the entrance and along the wiggler to obtain good e-beam transport through the wiggler, waveguide selection and characterization.

  7. Isotope separation using tuned laser and electron beam

    NASA Technical Reports Server (NTRS)

    Trajmar, Sandor (Inventor)

    1987-01-01

    The apparatus comprises means for producing an atomic beam containing the isotope of interest and other isotopes. Means are provided for producing a magnetic field traversing the path of the atomic beam of an intensity sufficient to broaden the energy domain of the various individual magnetic sublevels of the isotope of interest and having the atomic beam passing therethrough. A laser beam is produced of a frequency and polarization selected to maximize the activation of only individual magnetic sublevels of the isotope of interest with the portion of its broadened energy domain most removed from other isotopes with the stream. The laser beam is directed so as to strike the atomic beam within the magnetic field and traverse the path of the atomic beam whereby only the isotope of interest is activated by the laser beam. The apparatus further includes means for producing a collimated and high intensity beam of electrons of narrow energy distribution within the magnetic field which is aimed so as to strike the atomic beam while the atomic beam is simultaneously struck by the laser beam and at an energy level selected to ionize the activated isotope of interest but not ground state species included therewith. Deflection means are disposed in the usual manner to collect the ions.

  8. New fast beam profile monitor for electron-positron colliders

    SciTech Connect

    Bogomyagkov, A. V.; Gurko, V. F.; Zhuravlev, A. N.; Zubarev, P. V.; Kiselev, V. A.; Meshkov, O. I.; Muchnoi, N. Yu.; Selivanov, A. N.; Smaluk, V. V.; Khilchenko, A. D.

    2007-04-15

    A new fast beam profile monitor has been developed at the Budker Institute of Nuclear Physics. This monitor is based on the Hamamatsu multianode photomultiplier with 16 anode strips and provides turn-by-turn measurement of the transverse beam profile. The device is equipped with an internal memory, which has enough capacity to store 131 072 samples of the beam profile. The dynamic range of the beam profile monitor allows us to study turn-by-turn beam dynamics within the bunch charge range from 1 pC up to 10 nC. Using this instrument, we have investigated at the VEPP-4M electron-positron collider a number of beam dynamics effects which cannot be observed by other beam diagnostics tools.

  9. Beam acceleration by plasma-loaded free-electron devices

    NASA Astrophysics Data System (ADS)

    Tsui, K. H.; Serbeto, A.; D'olival, J. B.

    1998-01-01

    The use of a plasma-filled wiggler free-electron laser device operating near the plasma cutoff to accelerate electron beams is examined. Near the cutoff, the group velocity of the microwave field in the plasma is much less than the beam velocity. This scheme, therefore, operates in the pulse mode to accelerate electron beam bunches much shorter than the wiggler length. Between one bunch and the other, the wiggler is reloaded with microwave field. During the loading period, the laser-wiggler-plasma (SWL) Raman interaction generates a Langmuir mode with the laser and the wiggler as the primary energy sources. When the wiggler plasma is fully loaded with microwave field, a short electron bunch is fired into the device. In this accelerating period, the Langmuir mode is coupled to the laser-wiggler-beam (SWB) free-electron-laser interaction. The condition that the Langmuir phase velocity matches the free-electron-laser resonant beam velocity assures the simultaneous interaction of the SWL and SWB parametric processes. Beam acceleration is accomplished fundamentally via the space charge field of the Langmuir mode and the electron phase in the ponderomotive potential. Linear energy gain regime is accomplished when the phase velocity of the Langmuir mode is exactly equal to the speed of light.

  10. Energy measurement of electron beams by Compton scattering

    NASA Technical Reports Server (NTRS)

    Keppel, Cynthia

    1995-01-01

    A method has been proposed to utilize the well-known Compton scattering process as a tool to measure the centroid energy of a high energy electron beam at the 0.01% level. It is suggested to use the Compton scattering of an infrared laser off the electron beam, and then to measure the energy of the scattered gamma-rays very precisely using solid-state detectors. The technique proposed is applicable for electron beams with energies from 200 MeV to 16 GeV using presently available lasers. This technique was judged to be the most viable of all those proposed for beam energy measurements at the nearby Continuous Electron Beam Accelerator Facility (CEBAF). Plans for a prototype test of the technique are underway, where the main issues are the possible photon backgrounds associated with an electron accelerator and the electron and laser beam stabilities and diagnostics. The bulk of my ASEE summer research has been spent utilizing the expertise of the staff at the Aerospace Electronics Systems Division at LaRC to assist in the design of the test. Investigations were made regarding window and mirror transmission and radiation damage issues, remote movement of elements in ultra-high vacuum conditions, etc. The prototype test of the proposed laser backscattering method is planned for this December.

  11. Normal modes and mode transformation of pure electron vortex beams

    NASA Astrophysics Data System (ADS)

    Thirunavukkarasu, G.; Mousley, M.; Babiker, M.; Yuan, J.

    2017-02-01

    Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre-Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite-Gaussian beams. This article is part of the themed issue 'Optical orbital angular momentum'.

  12. Electron acoustic solitary waves in a magnetized plasma with nonthermal electrons and an electron beam

    NASA Astrophysics Data System (ADS)

    Singh, S. V.; Devanandhan, S.; Lakhina, G. S.; Bharuthram, R.

    2016-08-01

    A theoretical investigation is carried out to study the obliquely propagating electron acoustic solitary waves having nonthermal hot electrons, cold and beam electrons, and ions in a magnetized plasma. We have employed reductive perturbation theory to derive the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation describing the nonlinear evolution of these waves. The two-dimensional plane wave solution of KdV-ZK equation is analyzed to study the effects of nonthermal and beam electrons on the characteristics of the solitons. Theoretical results predict negative potential solitary structures. We emphasize that the inclusion of finite temperature effects reduces the soliton amplitudes and the width of the solitons increases by an increase in the obliquity of the wave propagation. The numerical analysis is presented for the parameters corresponding to the observations of "burst a" event by Viking satellite on the auroral field lines.

  13. Vortex stabilized electron beam compressed fusion grade plasma

    SciTech Connect

    Hershcovitch, Ady

    2014-03-19

    Most inertial confinement fusion schemes are comprised of highly compressed dense plasmas. Those schemes involve short, extremely high power, short pulses of beams (lasers, particles) applied to lower density plasmas or solid pellets. An alternative approach could be to shoot an intense electron beam through very dense, atmospheric pressure, vortex stabilized plasma.

  14. A Gridded Electron Gun for a Sheet Beam Klystron

    SciTech Connect

    Read, M.E.; Miram, G.; Ives, R.L.; Ivanov, V.; Krasnykh, A.; /SLAC

    2008-04-25

    This paper describes the development of an electron gun for a sheet beam klystron. Initially intended for accelerator applications, the gun can operate at a higher perveance than one with a cylindrically symmetric beam. Results of 2D and 3D simulations are discussed.

  15. Acceleration of electrons in strong beam-plasma interactions

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

    1984-01-01

    The effects of strong beam-plasma interactions on the electron population of the upper atmosphere have been investigated in an electron acceleration experiment performed with a sounding rocket. The rocket carried the Several Complex Experiments (SCEX) payload which included an electron accelerator, three disposable 'throwaway' detectors (TADs), and a stepped electron energy analyzer. The payload was launched in an auroral arc over the rocket at altitudes of 157 and 178 km, respectively. The performance characteristics of the instruments are discussed in detail. The data are combined with the results of laboratory measurements and show that electrons with energies of at least two and probably four times the injection energy of 2 keV were observed during strong beam-plasma interaction events. The interaction events occurred at pitch angles of 54 and 126 degrees. On the basis of the data it is proposed that the superenergization of the electrons is correlated with the length of the beam-plasma interaction region.

  16. Inactivation kinetics of Escherichia coli by pulsed electron beam.

    PubMed

    Chalise, P R; Hotta, E; Matak, K E; Jaczynski, J

    2007-09-01

    A novel and compact low-energy (keV) high-power pulsed electron beam (e-beam) that utilizes a secondary emission electron gun (SEEG) was designed and constructed. Escherichia coli JM 109 at a concentration of 10(6) CFU/mL was spread-plated on Luria-Bertani (LB) medium and subjected to the SEEG e-beam. The e-beam was administered as 1 or 5 pulses. The duration of a single pulse was constant at 5 micros, e-beam current density was constant at 25 mA/cm2, and e-beam energy varied between 60 and 82.5 keV. Following treatment with the SEEG e-beam, survivors of the irradiated E. coli samples were enumerated by a standard 10-fold dilution and spread-plated. The survivor curves were plotted on logarithmic scale as a function of e-beam dose. The D10-values were calculated as a negative reciprocal of the slope of the survivor curves. The D10-values for E. coli inactivated with 1- and 5-pulse SEEG e-beam were 0.0026 and 0.0217 Gy, respectively. These D10-values were considerably lower than published D10-values for E. coli inactivated with conventional high-energy continuous e-beam, likely due to shorter exposure time (t), greater current density (J), and a pulse mode of the SEEG e-beam. The SEEG e-beam showed promising results for microbial inactivation in a nonthermal manner; however, due to low energy of the SEEG e-beam, current applications are limited to surface decontamination. The SEEG e-beam may be an efficient processing step for surface inactivation of food-borne pathogens on ready-to-eat products, including fresh and leafy vegetables.

  17. Electron Beam Freeform Fabrication in the Space Environment

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M.; Hafley, Robert A.

    2007-01-01

    This viewgraph presentation describes the effect of microgravity on the fabrication of electron beam freeform (EBF) in aerospace environments. The contents include: 1) Electron Beam Freeform Fabrication (EBF3) Process Description; 2) Portable Electron Beam Freeform Fabrication System at NASA LaRC; 3) Electron Beam Freeform Fabrication in the Space Environment; 4) Effect of Gravity on Surface Tension; 5) Effect of Deposit Height on Cooling Path; 6) Microgravity Testing Aboard JSC's C-9; 7) Typical Test Flight Plates; 8) Direction and Height Trials for Process Control; 9) Effect of Wire Entry Direction into Molten Pool; 10) Microstructure of Single Layer EBF Deposits; 11) 0-g Deposit with Incorrect Standoff Distance; 12) Successful Demonstration of EBF in 0-g; and 13) Conclusion.

  18. Use of an Electron Beam for Stochastic Cooling

    SciTech Connect

    Yaroslave Derbenev

    2007-09-10

    Microwave instability of an electron beam can be used for a multiple increase in the collective response for the perturbation caused by a particle of a co-moving ion beam, i.e. for enhancement of friction force in electron cooling method. The low scale (hundreds GHz and higher frequency range) space charge or FEL type instabilities can be produced (depending on conditions) by introducing an alternating magnetic fields along the electron beam path. Beams’ optics and noise conditioning for obtaining a maximal cooling effect and related limitations will be discussed. The method promises to increase by a few orders of magnitude the cooling rate for heavy particle beams with a large emittance for a wide energy range with respect to either electron and conventional stochastic cooling.

  19. Commercial applications of electron beam advanced oxidation technology

    NASA Astrophysics Data System (ADS)

    Curry, Randy D.; Bosma, John T.

    1995-03-01

    Emerging commercial applications of electron-beam advanced oxidation technology offer a significant advancement in the treatment of waste steams. Both electron beam and X-ray (Brehmsstrahlung) advanced oxidation processes have been shown to be effective in the destruction of volatile and semivolatile organic compounds. Emerging commercial applications, however, far exceed in scope current applications of oxidation technologies for the destruction of simple semivolatile and volatile organic compounds in water. Emerging applications include direct treatment of contaminated soil, removal of metal ions from water and sterilization of water, sludges, and food. Application of electron beam advanced oxidation technologies are reviewed, along with electron- beam-generated X-ray (Brehmsstrahlung) advanced oxidation processes. Advantages of each technology are discussed along with advanced accelerator technologies which are applicable for commercial processing of waste streams. An overview of the U.S. companies and laboratories participating in this research area are included in this discussion.

  20. Electron beam irradiated silver nanowires for a highly transparent heater.

    PubMed

    Hong, Chan-Hwa; Oh, Seung Kyu; Kim, Tae Kyoung; Cha, Yu-Jung; Kwak, Joon Seop; Shin, Jae-Heon; Ju, Byeong-Kwon; Cheong, Woo-Seok

    2015-12-07

    Transparent heaters have attracted increasing attention for their usefulness in vehicle windows, outdoor displays, and periscopes. We present high performance transparent heaters based on Ag nanowires with electron beam irradiation. We obtained an Ag-nanowire thin film with 48 ohm/sq of sheet resistance and 88.8% (substrate included) transmittance at 550 nm after electron beam irradiation for 120 sec. We demonstrate that the electron beam creates nano-soldering at the junctions of the Ag nanowires, which produces lower sheet resistance and improved adhesion of the Ag nanowires. We fabricated a transparent heater with Ag nanowires after electron beam irradiation, and obtained a temperature of 51 °C within 1 min at an applied voltage of 7 V. The presented technique will be useful in a wide range of applications for transparent heaters.

  1. Inductive voltage adder (IVA) for submillimeter radius electron beam

    SciTech Connect

    Mazarakis, M.G.; Poukey, J.W.; Maenchen, J.E.

    1996-12-31

    The authors have already demonstrated the utility of inductive voltage adder accelerators for production of small-size electron beams. In this approach, the inductive voltage adder drives a magnetically immersed foilless diode to produce high-energy (10--20 MeV), high-brightness pencil electron beams. This concept was first demonstrated with the successful experiments which converted the linear induction accelerator RADLAC II into an IVA fitted with a small 1-cm radius cathode magnetically immersed foilless diode (RADLAC II/SMILE). They present here first validations of extending this idea to mm-scale electron beams using the SABRE and HERMES-III inductive voltage adders as test beds. The SABRE experiments are already completed and have produced 30-kA, 9-MeV electron beams with envelope diameter of 1.5-mm FWHM. The HERMES-III experiments are currently underway.

  2. Production of a sub-10 fs electron beam with 107 electrons

    NASA Astrophysics Data System (ADS)

    Han, Jang-Hui

    2011-05-01

    We study the possibility to produce a 1.6 pC electron beam (107 electrons) with a bunch length of less than 10 fs and a beam energy of a few MeV. Such a short, relativistic beam will be useful for an electron diffraction experiment with a 10 fs time resolution. An electron beam with 107 electrons will allow a single-shot experiment with a laser pulse pump and an electron beam probe. In this design, an S-band photocathode gun is used for generating and accelerating a beam and a buncher consisting of two S-band four-cell cavities is used for temporally compressing the beam. Focusing solenoids control the beam transverse divergence and size at the sample. Numerical optimization is carried out to achieve a beam with a 4 fs full-width-at-half-maximum length, a 26 microradian root-mean-square divergence, and a 2 nm transverse coherence length at a 3.24 MeV beam energy. When state-of-the-art rf stability is considered, beam arrival time jitter at the sample is calculated to be about 10 fs.

  3. Mixed feed and its ingredients electron beam decontamination

    NASA Astrophysics Data System (ADS)

    Bezuglov, V. V.; Bryazgin, A. A.; Vlasov, A. Yu; Voronin, L. A.; Ites, Yu V.; Korobeynikov, M. V.; Leonov, S. V.; Leonova, M. A.; Tkachenko, V. O.; Shtarklev, E. A.; Yuskov, Yu G.

    2017-01-01

    Electron beam treatment is used for food processing for decades to prevent or minimize food losses and prolong storage time. This process is also named cold pasteurization. Mixed feed ingredients supplied in Russia regularly occur to be contaminated. To reduce contamination level the contaminated mixed feed ingredients samples were treated by electron beam with doses from 2 to 12 kGy. The contamination levels were decreased to the level that ensuring storage time up to 1 year.

  4. Electron Beam Collimation for the Next Generation Light Source

    SciTech Connect

    Steier, C.; Emma, P.; Nishimura, H.; Papadopoulos, C.; Sannibale, F.

    2013-05-20

    The Next Generation Light Source will deliver high (MHz) repetition rate electron beams to an array of free electron lasers. Because of the significant average current in such a facility, effective beam collimation is extremely important to minimize radiation damage to undulators, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. This paper describes the early conceptual design of a collimation system, as well as initial results of simulations to test its effectiveness.

  5. An Undulator-Based Laser Wakefield Accelerator Electron Beam Diagnostic

    NASA Astrophysics Data System (ADS)

    Bakeman, Michael S.

    Currently particle accelerators such as the Large Hadron Collider use RF cavities with a maximum field gradient of 50-100 MV/m to accelerate particles over long distances. A new type of plasma based accelerator called a Laser Plasma Accelerator (LPA) is being investigated at the LOASIS group at Lawrence Berkeley National Laboratory which can sustain field gradients of 10-100 GV/m. This new type of accelerator offers the potential to create compact high energy accelerators and light sources. In order to investigate the feasibility of producing a compact light source an undulator-based electron beam diagnostic for use on the LOASIS LPA has been built and calibrated. This diagnostic relies on the principal that the spectral analysis of synchrotron radiation from an undulator can reveal properties of the electron beam such as emittance, energy and energy spread. The effects of electron beam energy spread upon the harmonics of undulator produced synchrotron radiation were derived from the equations of motion of the beam and numerically simulated. The diagnostic consists of quadrupole focusing magnets to collimate the electron beam, a 1.5 m long undulator to produce the synchrotron radiation, and a high resolution high gain XUV spectrometer to analyze the radiation. The undulator was aligned and tuned in order to maximize the flux of synchrotron radiation produced. The spectrometer was calibrated at the Advanced Light Source, with the results showing the ability to measure electron beam energy spreads at resolutions as low as 0.1% rms, a major improvement over conventional magnetic spectrometers. Numerical simulations show the ability to measure energy spreads on realistic LPA produced electron beams as well as the improvements in measurements made with the quadrupole magnets. Experimentally the quadrupoles were shown to stabilize and focus the electron beams at specific energies for their insertion into the undulator, with the eventual hope of producing an all optical

  6. New data on electron-beam purification of wastewater

    NASA Astrophysics Data System (ADS)

    Pikaev, A. K.

    2002-11-01

    Recent environmental applications of radiation technology, developed in the author's laboratory, are presented in this paper. They are electron-beam and coagulation purification of molasses distillery slops from distillery-produced ethyl alcohol by fermentation of plant materials, electron-beam purification of wastewater from carboxylic acids (for example, formic acid) and removal of petroleum products (diesel fuel, motor oil and residual fuel oil) from water by γ-irradiation.

  7. Characterization of electron contamination in megavoltage photon beams

    SciTech Connect

    Medina, Antonio Lopez; Teijeiro, Antonio; Garcia, Juan; Esperon, Jorge; Terron, J. Antonio; Ruiz, Diego P.; Carrion, Maria C.

    2005-05-01

    The purpose of the present study is to characterize electron contamination in photon beams in different clinical situations. Variations with field size, beam modifier (tray, shaping block) and source-surface distance (SSD) were studied. Percentage depth dose measurements with and without a purging magnet and replacing the air by helium were performed to identify the two electron sources that are clearly differentiated: air and treatment head. Previous analytical methods were used to fit the measured data, exploring the validity of these models. Electrons generated in the treatment head are more energetic and more important for larger field sizes, shorter SSD, and greater depths. This difference is much more noticeable for the 18 MV beam than for the 6 MV beam. If a tray is used as beam modifier, electron contamination increases, but the energy of these electrons is similar to that of electrons coming from the treatment head. Electron contamination could be fitted to a modified exponential curve. For machine modeling in a treatment planning system, setting SSD at 90 cm for input data could reduce errors for most isocentric treatments, because they will be delivered for SSD ranging from 80 to 100 cm. For very small field sizes, air-generated electrons must be considered independently, because of their different energetic spectrum and dosimetric influence.

  8. Characterization of electron contamination in megavoltage photon beams.

    PubMed

    Lopez Medina, Antonio; Teijeiro, Antonio; Garcia, Juan; Esperon, Jorge; Terron, J Antonio; Ruiz, Diego P; Carrion, Maria C

    2005-05-01

    The purpose of the present study is to characterize electron contamination in photon beams in different clinical situations. Variations with field size, beam modifier (tray, shaping block) and source-surface distance (SSD) were studied. Percentage depth dose measurements with and without a purging magnet and replacing the air by helium were performed to identify the two electron sources that are clearly differentiated: air and treatment head. Previous analytical methods were used to fit the measured data, exploring the validity of these models. Electrons generated in the treatment head are more energetic and more important for larger field sizes, shorter SSD, and greater depths. This difference is much more noticeable for the 18 MV beam than for the 6 MV beam. If a tray is used as beam modifier, electron contamination increases, but the energy of these electrons is similar to that of electrons coming from the treatment head. Electron contamination could be fitted to a modified exponential curve. For machine modeling in a treatment planning system, setting SSD at 90 cm for input data could reduce errors for most isocentric treatments, because they will be delivered for SSD ranging from 80 to 100 cm. For very small field sizes, air-generated electrons must be considered independently, because of their different energetic spectrum and dosimetric influence.

  9. Motion of ionized electrons under the intense electromagnetic field of the beam

    SciTech Connect

    Kamiya, Y.

    1983-09-01

    The motion of an electron ionized from residual gas by the beam becomes relativistic in the case of a high-density beam as in SLC, while the ions produced by the beam remain nonrelativistic. The ionized relativistic electron will be dragged by the beam, and will go away from the beam (electron beam) before the beam passes, even for the very short bunch of SLC. In this note, we discuss the motions of electrons ionized by the electron beam or by the positron beam. We assume that the density of the beam is uniform and the shape cylindrical (transversely round and longitudinally rectangular).

  10. Microbunched electron cooling for high-energy hadron beams.

    PubMed

    Ratner, D

    2013-08-23

    Electron and stochastic cooling are proven methods for cooling low-energy hadron beams, but at present there is no way of cooling hadrons as they near the TeV scale. In the 1980s, Derbenev suggested that electron instabilities, such as free-electron lasers, could create collective space charge fields strong enough to correct the hadron energies. This Letter presents a variation on Derbenev's electron cooling scheme using the microbunching instability as the amplifier. The large bandwidth of the instability allows for faster cooling of high-density beams. A simple analytical model illustrates the cooling mechanism, and simulations show cooling rates for realistic parameters of the Large Hadron Collider.

  11. Electron-Cloud Effects on Heavy-Ion Beams

    SciTech Connect

    Azevedo, T; Friedman, A; Cohen, R; Vay, J

    2004-03-29

    Stray electrons can be introduced in positive-charge accelerators for heavy ion fusion (or other applications) as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary-electron emission. We are developing a capability for self-consistent simulation of ion beams with the electron clouds they produce. We report on an ingredient in this capability, the effect of specified electron cloud distributions on the dynamics of a coasting ion beam. We consider here electron distributions with axially varying density, centroid location, or radial shape, and examine both random and sinusoidally varying perturbations. We find that amplitude variations are most effective in spoiling ion beam quality, though for sinusoidal variations which match the natural ion beam centroid oscillation or breathing mode frequencies, the centroid and shape perturbations can also be effective. We identify a possible instability associated with resonance with the beam-envelope ''breathing'' mode. One conclusion from this study is that heavy-ion beams are surprisingly robust to electron clouds, compared to a priori expectations.

  12. Reinforcing multiwall carbon nanotubes by electron beam irradiation

    SciTech Connect

    Duchamp, Martial; Meunier, Richard; Smajda, Rita; Mionic, Marijana; Forro, Laszlo; Magrez, Arnaud; Seo, Jin Won; Song, Bo; Tomanek, David

    2010-10-15

    We study the effect of electron beam irradiation on the bending modulus of multiwall carbon nanotubes grown by chemical vapor deposition. Atomic force microscopy observations of the nanotube deflection in the suspended-beam geometry suggest an internal, reversible stick-slip motion prior to irradiation, indicating presence of extended defects. Upon electron beam irradiation, nanotubes with an initial bending modulus exceeding 10 GPa initially get stiffer, before softening at high doses. Highly defective nanotubes with smaller initial bending moduli do not exhibit the initial reinforcement. These data are explained by ab initio molecular dynamics calculations suggesting a spontaneous cross-linking of neighboring nanotube walls at extended vacancy defects created by the electron beam, in agreement with electron microscopy observations. At low defect concentration, depending on the edge morphology, the covalent bonds between neighboring nanotube walls cause reinforcement by resisting relative motion of neighboring walls. At high concentration of defects that are present initially or induced by high electron beam dose, the structural integrity of the entire system suffers from increasing electron beam damage.

  13. Angular-momentum-dominated electron beams and flat-beam generation

    SciTech Connect

    Sun, Yin-e

    2005-06-01

    In the absence of external forces, if the dynamics within an electron beam is dominated by its angular momentum rather than other effects such as random thermal motion or self Coulomb-repulsive force (i.e., space-charge force), the beam is said to be angular-momentum-dominated. Such a beam can be directly applied to the field of electron-cooling of heavy ions; or it can be manipulated into an electron beam with large transverse emittance ratio, i.e., a flat beam. A flat beam is of interest for high-energy electron-positron colliders or accelerator-based light sources. An angular-momentum-dominated beam is generated at the Fermilab/NICADD photoinjector Laboratory (FNPL) and is accelerated to an energy of 16 MeV. The properties of such a beam is investigated systematically in experiment. The experimental results are in very good agreement with analytical expectations and simulation results. This lays a good foundation for the transformation of an angular-momentum-dominated beam into a flat beam. The round-to-flat beam transformer is composed of three skew quadrupoles. Based on a good knowledge of the angular-momentum-dominated beam, the quadrupoles are set to the proper strengths in order to apply a total torque which removes the angular momentum, resulting in a flat beam. For bunch charge around 0.5 nC, an emittance ratio of 100 ± 5 was measured, with the smaller normalized root-mean-square emittance around 0.4 mm-mrad. Effects limiting the flat-beam emittance ratio are investigated, such as the chromatic effects in the round-to-flat beam transformer, asymmetry in the initial angular-momentum-dominated beam, and space-charge effects. The most important limiting factor turns out to be the uncorrelated emittance growth caused by space charge when the beam energy is low, for example, in the rf gun area. As a result of such emittance growth prior to the round-to-flat beam transformer, the emittance ratio achievable in simulation decreases from orders of thousands to

  14. Electron beam driven lower hybrid waves in a dusty plasma

    SciTech Connect

    Prakash, Ved; Vijayshri; Sharma, Suresh C.; Gupta, Ruby

    2013-05-15

    An electron beam propagating through a magnetized dusty plasma drives electrostatic lower hybrid waves to instability via Cerenkov interaction. A dispersion relation and the growth rate of the instability for this process have been derived taking into account the dust charge fluctuations. The frequency and the growth rate of the unstable wave increase with the relative density of negatively charged dust grains. Moreover, the growth rate of the instability increases with beam density and scales as the one-third power of the beam density. In addition, the dependence of the growth rate on the beam velocity is also discussed.

  15. Noninvasive measurement of electron-beam size with diamagnetic loops

    SciTech Connect

    Ekdahl, Carl

    2001-07-01

    Diamagnetic loops can be used as a noninvasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. A comprehensive theory for interpreting data from a diamagnetic loop is developed. It is shown that the change in flux through a diamagnetic loop can be simply related to the rms beam radius to high accuracy, regardless of the details of the current profile, when the ratio of beam current to Alfven current I{sub b}/I{sub A} is small. The difficulty in making this measurement lies in the fact that the diamagnetic-loop signal is also small to the same order.

  16. Electron Beam Lifetime in SPEAR3: Measurement and Simulation

    SciTech Connect

    Corbett, J.; Huang, X.; Lee, M.; Lui, P.; Sayyar-Rodsari, B.; /Pavilon Tech., Austin

    2007-12-19

    In this paper we report on electron beam lifetime measurements as a function of scraper position, RF voltage and bunch fill pattern in SPEAR3. We then outline development of an empirical, macroscopic model using the beam-loss rate equation. By identifying the dependence of loss coefficients on accelerator and beam parameters, a numerically-integrating simulator can be constructed to compute beam decay with time. In a companion paper, the simulator is used to train a parametric, non-linear dynamics model for the system [1].

  17. determination of current density distribution in an electron beam

    NASA Astrophysics Data System (ADS)

    Kandel, Yudhishthir Prasad

    Electron beams are useful in many applications because they can be focused down to a spot far exceeding the physical limit of focusing visible light or x-rays. Additionally, electron beams are useful in transferring concentrated amounts of energy to a very small well defined region of a target for a fixed duration. This has led to the development of both scanning electron microscopes (SEMs) and electron beam lithography. The goal of this work was to develop a general method that accurately and easily yields the best estimate of the electron current density distribution of a focused electron beam, known as point spread function (PSF). The method developed is fast, easy to use and accurate. Two specific areas of research have been addressed for PSF determination. The first is concerned with the monotonic response of EUV photoresist as a function of electron beam dose. An external metrology is used for mapping the change in thickness that is smaller than the beam spot size. The method developed in this study simultaneously gives the photo-resist thickness change as a function of electron dose and electron beam PSF. A second thrust of this research has been to develop set of PSF characterization approaches that apply to the SEM. Here a knowledge of the PSF offers many benefits including the ability to monitor and optimize SEM performance such as astigmatism control. Perhaps, even more importantly, a knowledge of the PSF combined with a series of well-defined experimental steps has led to the development of new methods for improving the resolution of SEM images through computational means rather than very costly and complex equipment modification.

  18. Note: Characteristic beam parameter for the line electron gun

    SciTech Connect

    Iqbal, M.; Islam, G. U.; Zhou, Z.; Chi, Y.

    2013-11-15

    We have optimized the beam parameters of line source electron gun using Stanford Linear Accelerator Centre electron beam trajectory program (EGUN), utilizing electrostatic focusing only. We measured minimum beam diameter as 0.5 mm that corresponds to power density of 68.9 kW/cm{sup 2} at 13.5 mm in the post-anode region which is more than two-fold (33 kW/cm{sup 2}), of the previously reported results. The gun was operated for the validation of the theoretical results and found in good agreement. The gun is now without any magnetic and electrostatic focusing thus much simpler and more powerful.

  19. Runaway electron beam control for longitudinally pumped metal vapor lasers

    NASA Astrophysics Data System (ADS)

    Kolbychev, G. V.; Kolbycheva, P. D.

    1995-08-01

    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  20. Electromagnetic beam modes driven by anisotropic electron streams

    NASA Technical Reports Server (NTRS)

    Goldman, Martin V.; Newman, David

    1987-01-01

    A theory is presented which provides an explanation for recent laboratory observations of a 'new electromagnetic' mode in a non-Maxwellian high-beta plasma' and suggests a likely relevance of these modes to space plasmas. Unstable parallel-propagating waves, which can be beam modes or whistlers, depending mainly on the degree of velocity anisotropy in a weak electron beam, are found. In the beam-mode limit relevant to the experiment, this is a kinetic Weibel instability, enhanced by a parallel magnetic field. The frequency of the mode can be above or below the electron cyclotron frequency.

  1. Development of High Power Electron Beam Measuring and Analyzing System for Microwave Vacuum Electron Devices

    NASA Astrophysics Data System (ADS)

    Ruan, C. J.; Wu, X. L.; Li, Q. S.; Li, C. S.

    The measurement and analysis of high power electron beam during its formation and transmission are the basic scientific problems and key techniques for the development of high performance microwave vacuum electron devices, which are widely used in the fields of military weapon, microwave system and scientific instruments. In this paper, the dynamic parameters measurement and analysis system being built in Institute of Electronics, Chinese Academy of Sciences (IECAS) recently are introduced. The instrument are designed to determine the cross-section, the current density, and the energy resolution of the high power electron beam during its formation and transmission process, which are available both for the electron gun and the electron optics system respectively. Then the three dimension trajectory images of the electron beam can be rebuilt and display with computer controlled data acquisition and processing system easily. Thus, much more complicated structures are considered and solved completely to achieve its detection and analysis, such as big chamber with 10-6 Pa high vacuum system, the controlled detector movement system in axis direction with distance of 600 mm inside the vacuum chamber, the electron beam energy analysis system with high resolution of 0.5%, and the electron beam cross-section and density detector using the YAG: Ce crystal and CCD imaging system et al. At present, the key parts of the instrument have been finished, the cross-section experiment of the electron beam have been performed successfully. Hereafter, the instrument will be used to measure and analyze the electron beam with the electron gun and electron optics system for the single beam and multiple beam klystron, gyrotron, sheet beam device, and traveling wave tube etc. thoroughly.

  2. Whistler-mode radiation from the Spacelab 2 electron beam

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Steinberg, J. T.; Banks, P. M.; Bush, R. I.

    1986-01-01

    During the Spacelab 2 mission the Plasma Diagnostics Package (PDP) performed a fly-around of the Shuttle at distances of up to 300 meters while an electron beam was being ejected from the Shuttle. A magnetic conjunction of the Shuttle and the PDP while the electron gun was operating in a steady (DC) mode is discussed. During this conjunction, the PDP detected a clear funnel-shaped emission that is believed to be caused by whistler-mode emission from the beam. Ray-path calculations show that the shape of the funnel can be accounted for by whistler-mode waves propagating near the resonance cone. Because the beam and waves are propagating in the same direction, the radiation must be produced by a Landau interaction with the beam. Other types of waves generated by the beam are also described.

  3. Electron-beam induced recrystallization in amorphous apatite

    SciTech Connect

    Bae, In-Tae; Zhang, Yanwen; Weber, William J.; Higuchi, Mikio; Giannuzzi, Lucille

    2007-01-10

    Electron-beam-induced recrystallization of irradiation-induced amorphous Sr2Nd8(SiO4)6O2 is investigated in situ using transmission electron microscopy with 200 keV electrons at room temperature. Epitaxial recrystallization is observed from both the amorphous/crystalline interface and the surface, and the recrystallization is more pronounced with increasing electron-beam flux. Since the temperature increase induced by electron-beam irradiation is estimated to be less than 7 K and maximum energies transferred to target atoms are below the displacement energies, ionization-induced processes are considered to be the primary mechanisms for the solid-phase epitaxial recrystallization observed in the present study.

  4. An Electron Beam Profile Instrument Based on FBGs

    PubMed Central

    Sporea, Dan; Stăncălie, Andrei; Becherescu, Nicu; Becker, Martin; Rothhardt, Manfred

    2014-01-01

    Along with the dose rate and the total irradiation dose measurements, the knowledge of the beam localization and the beam profile/energy distribution in the beam are parameters of interest for charged particle accelerator installations when they are used in scientific investigations, industrial applications or medical treatments. The transverse profile of the beam, its position, its centroid location, and its focus or flatness depend on the instrument operating conditions or on the beam exit setup. Proof-of-concept of a new type of charged particle beam diagnostics based on fiber Bragg gratings (FBGs) was demonstrated. Its operating principle relies on the measurement of the peak wavelength changes for an array of FBG sensors as function of the temperature following the exposure to an electron beam. Periodically, the sensor irradiation is stopped and the FBG are force cooled to a reference temperature with which the temperature influencing each sensor during beam exposure is compared. Commercially available FBGs, and FBGs written in radiation resistant optical fibers, were tested under electron beam irradiation in order to study their possible use in this application. PMID:25157554

  5. Compact electron-beam source for formation of neutral beams of very low vapor pressure materials

    NASA Technical Reports Server (NTRS)

    Rutherford, J. A.; Vroom, D. A.

    1978-01-01

    In order to form metal vapors for neutral beam studies, an electron-beam heater and a power supply have been designed. The source, which measures about 30 x 50 x 70 mm, consists of a filament, accelerating plate (defined by pole pieces), and a supported target. The electrons from the filament are focused by the field penetration through a 2 mm slit in the high-voltage cage. They are then accelerated to about 5 kV to a ground plate. The electrons then follow a path in the magnetic field and strike the sample to be heated on its front surface. The assembly is attached to a water-cooled base plate. The electron beam source has produced beams of Ta and C particles with densities of about 10 to the 8th power/cu cm.

  6. Electrostatic ion cyclotron, beam-plasma, and lower hybrid waves excited by an electron beam

    SciTech Connect

    Singh, N.; Conrad, J.R.; Schunk, R.W.

    1985-06-01

    It is pointed out that electrostatic ion cyclotron (EIC) waves have been extensively investigated in connection with both space and laboratory plasmas. The present investigation has the objective to study the excitation of low-frequency waves in a multiion plasma by electron beams. The frequencies considered range from below the lowest gyrofrequency of the heaviest ion to about the lower hybrid frequency. It is shown that electron-beam instabilities can produce peaks in the growth rate below the cyclotron frequency of each ion species if nonzero perpendicular wave number effects are included in the ion dynamics. The dispersion relations for neutralized ion Bernstein (NIB) and pure ion Bernstein (PIB) waves are considered along with an instability analysis for a cold plasma and warm electron beam, the electron beam-plasma mode, banded ion cyclotron (EIC) waves with small perpendicular wavelengths, and the growth lengths of the waves. 39 references.

  7. Electrostatic ion cyclotron, beam-plasma, and lower hybrid waves excited by an electron beam

    NASA Technical Reports Server (NTRS)

    Singh, N.; Conrad, J. R.; Schunk, R. W.

    1985-01-01

    It is pointed out that electrostatic ion cyclotron (EIC) waves have been extensively investigated in connection with both space and laboratory plasmas. The present investigation has the objective to study the excitation of low-frequency waves in a multiion plasma by electron beams. The frequencies considered range from below the lowest gyrofrequency of the heaviest ion to about the lower hybrid frequency. It is shown that electron-beam instabilities can produce peaks in the growth rate below the cyclotron frequency of each ion species if nonzero perpendicular wave number effects are included in the ion dynamics. The dispersion relations for neutralized ion Bernstein (NIB) and pure ion Bernstein (PIB) waves are considered along with an instability analysis for a cold plasma and warm electron beam, the electron beam-plasma mode, banded ion cyclotron (EIC) waves with small perpendicular wavelengths, and the growth lengths of the waves.

  8. Electron-beam induced synthesis of nanostructures: a review.

    PubMed

    Gonzalez-Martinez, I G; Bachmatiuk, A; Bezugly, V; Kunstmann, J; Gemming, T; Liu, Z; Cuniberti, G; Rümmeli, M H

    2016-06-02

    As the success of nanostructures grows in modern society so does the importance of our ability to control their synthesis in precise manners, often with atomic precision as this can directly affect the final properties of the nanostructures. Hence it is crucial to have both deep insight, ideally with real-time temporal resolution, and precise control during the fabrication of nanomaterials. Transmission electron microscopy offers these attributes potentially providing atomic resolution with near real time temporal resolution. In addition, one can fabricate nanostructures in situ in a TEM. This can be achieved with the use of environmental electron microscopes and/or specialized specimen holders. A rather simpler and rapidly growing approach is to take advantage of the imaging electron beam as a tool for in situ reactions. This is possible because there is a wealth of electron specimen interactions, which, when implemented under controlled conditions, enable different approaches to fabricate nanostructures. Moreover, when using the electron beam to drive reactions no specialized specimen holders or peripheral equipment is required. This review is dedicated to explore the body of work available on electron-beam induced synthesis techniques with in situ capabilities. Particular emphasis is placed on the electron beam-induced synthesis of nanostructures conducted inside a TEM, viz. the e-beam is the sole (or primary) agent triggering and driving the synthesis process.

  9. Incident-beam effects in electron-stimulated Auger-electron diffraction

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Cao, Jianming

    1991-04-01

    We have examined incident-beam effects in electron-stimulated Auger-electron diffraction (AED) on a cleaved GaAs(110) surface. The results indicate that incident-beam diffraction is significant in an AED experiment, and that the dissipative nature of the incident beam in contributing to the Auger process must be accounted for. We have developed a qualitative model that describes the trend of the polar-angle dependence of the Auger intensity for both the incident and exit beams. In calculating the diffraction features, we used a zeroth-order approximation to simulate the dissipation of the incident beam, which is found to adequately describe the experimental data.

  10. Electron cyclotron beam measurement system in the Large Helical Device

    SciTech Connect

    Kamio, S. Takahashi, H.; Kubo, S.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Osakabe, M.; Mutoh, T.

    2014-11-15

    In order to evaluate the electron cyclotron (EC) heating power inside the Large Helical Device vacuum vessel and to investigate the physics of the interaction between the EC beam and the plasma, a direct measurement system for the EC beam transmitted through the plasma column was developed. The system consists of an EC beam target plate, which is made of isotropic graphite and faces against the EC beam through the plasma, and an IR camera for measuring the target plate temperature increase by the transmitted EC beam. This system is applicable to the high magnetic field (up to 2.75 T) and plasma density (up to 0.8 × 10{sup 19} m{sup −3}). This system successfully evaluated the transmitted EC beam profile and the refraction.

  11. Diffusion of Echo 7 electron beams during bounce motion

    SciTech Connect

    Nemzek, R.J.

    1992-01-01

    The Echo 7 sounding rocket experiment injected electron beams into the magnetosphere and detected them after one or more bounces along field lines near L = 6.5. Waves with equatorial amplitudes of a few mV/m diffused the beams so that only {approx}2O% of the initial current returned to the rocket altitude in the northern hemisphere. On successive bounces the electron flux continued to drop at the same rate. These results imply a lifetime of {approx}1.7 for 20 kev electrons just outside of the loss cone. comparison with other Echo flights shows that the beam return is dependent upon geomagnetic conditions: low activity causes there to be less scattering, while high activity can actually prevent detection of the returning beam.

  12. Diffusion of Echo 7 electron beams during bounce motion

    SciTech Connect

    Nemzek, R.J.

    1992-08-01

    The Echo 7 sounding rocket experiment injected electron beams into the magnetosphere and detected them after one or more bounces along field lines near L = 6.5. Waves with equatorial amplitudes of a few mV/m diffused the beams so that only {approx}2O% of the initial current returned to the rocket altitude in the northern hemisphere. On successive bounces the electron flux continued to drop at the same rate. These results imply a lifetime of {approx}1.7 for 20 kev electrons just outside of the loss cone. comparison with other Echo flights shows that the beam return is dependent upon geomagnetic conditions: low activity causes there to be less scattering, while high activity can actually prevent detection of the returning beam.

  13. Do Unpolarized Electrons Affect the Polarization of a Stored Beam?

    SciTech Connect

    Rathmann, Frank

    2009-08-04

    We present a short overview of the PAX physics case for polarized antiprotons. In order to progress towards a stored polarized antiproton beam, it is crucial to understand the interaction of polarized protons with unpolarized electrons. Therefore investigations that address in particular the contributions of electrons to the polarization buildup of a stored proton beam are presented here in more detail. The measurement of the depolarizing p-vectore cross section settled a long-standing controversy about the role of electrons in the polarization buildup of a stored beam by spin-filtering. Instead of studying the buildup of polarization in an initially unpolarized beam, here the inverse situation was investigated by observation of the depolarization of an initially polarized beam. For the first time, electrons in the electron cooler have been used as a target to study their depolarizing effect on a 49.3 MeV proton beam orbiting in COSY. The foreseen spin-filtering experiments at COSY-Juelich and at the AD of CERN are briefly discussed as well.

  14. PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons

    SciTech Connect

    Adeyemi, Adeleke H.

    2015-09-01

    Polarized positron beams have been identified as either an essential or a significant ingredient for the experimental program of both the present and next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). An experiment demonstrating a new method for producing polarized positrons has been performed at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e⁻/e⁺ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high-Z conversion target. PEPPo demonstrated the effective transfer of spin-polarization of an 8.2 MeV/c polarized (P~85%) electron beam to positrons produced in varying thickness tungsten production targets, and collected and measured in the range of 3.1 to 6.2 MeV/c. In comparison to other methods this technique reveals a new pathway for producing either high-energy or thermal polarized positron beams using a relatively low polarized electron beam energy (~10MeV) .This presentation will describe the PEPPo concept, the motivations of the experiment and high positron polarization achieved.

  15. Observations of ionospheric electron beams in the plasma sheet.

    PubMed

    Zheng, H; Fu, S Y; Zong, Q G; Pu, Z Y; Wang, Y F; Parks, G K

    2012-11-16

    Electrons streaming along the magnetic field direction are frequently observed in the plasma sheet of Earth's geomagnetic tail. The impact of these field-aligned electrons on the dynamics of the geomagnetic tail is however not well understood. Here we report the first detection of field-aligned electrons with fluxes increasing at ~1 keV forming a "cool" beam just prior to the dissipation of energy in the current sheet. These field-aligned beams at ~15 R(E) in the plasma sheet are nearly identical to those commonly observed at auroral altitudes, suggesting the beams are auroral electrons accelerated upward by electric fields parallel (E([parallel])) to the geomagnetic field. The density of the beams relative to the ambient electron density is δn(b)/n(e)~5-13% and the current carried by the beams is ~10(-8)-10(-7) A m(-2). These beams in high β plasmas with large density and temperature gradients appear to satisfy the Bohm criteria to initiate current driven instabilities.

  16. Transverse profile of the electron beam for the RHIC electron lenses

    SciTech Connect

    Gu, X.; Altinbas, Z.; Costanzo, M.; Fischer, W.; Gassner, D. M.; Hock, J.; Luo, Y.; Miller, T.; Tan, Y.; Thieberger, P.; Montag, C.; Pikin, A. I.

    2015-07-10

    To compensate for the beam-beam effects from the proton-proton interactions at the two interaction points IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are constructing two electron lenses (e-lenses) that we plan to install in the interaction region IR10. Before installing them, the electron gun, collector, instrumentation were tested and the electron beam properties were qualified on an electron lens test bench. We will present the test results and discuss our measurement of the electron beam current and of the electron gun perveance. We achieved a maximum current of 1 A with 5 kV energy for both the pulsed- and the DC-beam (which is a long turn-by-turn pulse beam). We measured beam transverse profiles with an Yttrium Aluminum Garnet (YAG) screen and pinhole detector, and compared those to simulated beam profiles. Measurements of the pulsed electron beam stability were obtained by measuring the modulator voltage.

  17. Transverse profile of the electron beam for the RHIC electron lenses

    DOE PAGES

    Gu, X.; Altinbas, Z.; Costanzo, M.; ...

    2015-07-10

    To compensate for the beam-beam effects from the proton-proton interactions at the two interaction points IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are constructing two electron lenses (e-lenses) that we plan to install in the interaction region IR10. Before installing them, the electron gun, collector, instrumentation were tested and the electron beam properties were qualified on an electron lens test bench. We will present the test results and discuss our measurement of the electron beam current and of the electron gun perveance. We achieved a maximum current of 1 A with 5 kV energy for bothmore » the pulsed- and the DC-beam (which is a long turn-by-turn pulse beam). We measured beam transverse profiles with an Yttrium Aluminum Garnet (YAG) screen and pinhole detector, and compared those to simulated beam profiles. Measurements of the pulsed electron beam stability were obtained by measuring the modulator voltage.« less

  18. Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

    NASA Astrophysics Data System (ADS)

    Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; Ji, Wei

    2015-08-01

    Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. It is shown that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections.

  19. Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

    DOE PAGES

    Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; ...

    2015-08-04

    Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Importantmore » swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections.« less

  20. Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

    SciTech Connect

    Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; Ji, Wei

    2015-08-04

    Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections.

  1. SHEEBA: A spatial high energy electron beam analyzer

    NASA Astrophysics Data System (ADS)

    Galimberti, Marco; Giulietti, Antonio; Giulietti, Danilo; Gizzi, Leonida A.

    2005-05-01

    Electron bunches with large energy and angle spread are not easy to be analyzed with conventional spectrometers. In this article, a device for the detection of high energy electrons is presented. This detector, based on the traces left by electrons on a stack of dosimetric films, together with an original numerical algorithm for traces deconvolution, is able to characterize both angularly and spectrally (up to some mega-electron-volts) a broad-spectrum electron bunch. A numerical test was successfully performed with a virtual electron beam, which was in turn reconstructed using a Montecarlo code (based on the CERN library GEANT4). Due to its simplicity and small size, the spatial high energy electron beam analyzer (SHEEBA) detector is particularly suitable to be used in laser plasma acceleration experiments.

  2. Energy Spread Reduction of Electron Beams Produced via Laser Wake

    SciTech Connect

    Pollock, Bradley Bolt

    2012-01-01

    Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis describes a series of experiments which investigates the physics of LWFA in the self-guided blowout regime. Beginning with high density gas jet experiments the scaling of the LWFA-produced electron beam energy with plasma electron density is found to be in excellent agreement with both phenomenological theory and with 3-D PIC simulations. It is also determined that self-trapping of background electrons into the wake exhibits a threshold as a function of the electron density, and at the densities required to produce electron beams with energies exceeding 1 GeV a different mechanism is required to trap charge into low density wakes. By introducing small concentrations of high-Z gas to the nominal He background the ionization-induced injection mechanism is enabled. Electron trapping is observed at densities as low as 1.3 x 1018 cm-3 in a gas cell target, and 1.45 GeV electrons are demonstrated for the first time from LWFA. This is currently the highest electron energy ever produced from LWFA. The ionization-induced trapping mechanism is also shown to generate quasi-continuous electron beam energies, which is undesirable for accelerator applications. By limiting the region over which ionization-induced trapping occurs, the energy spread of the electron beams can be controlled. The development of a novel two-stage gas cell target provides the capability to tailor the gas composition in the longitudinal direction, and confine the trapping process to occur only in a

  3. Turbulent relaxation and meta-stable equilibrium states of an electron plasma

    NASA Astrophysics Data System (ADS)

    Rodgers, Douglas J.

    A Malmberg-Penning electron trap allows for the experimental study of nearly ideal, two-dimensional (2D) inviscid (Euler) hydrodynamics. This is perhaps the simplest case of self organizing nonlinear turbulence, and is therefore a paradigm for dynamo theory, Taylor relaxation, selective decay and other nonlinear fluid processes. The dynamical relaxation of a pure electron plasma in the guiding-center-drift approximation is studied, comparing experiments, numerical simulations and statistical theories of weakly-dissipative 2D turbulence. The nonuniform metastable equilibrium states resulting from turbulent evolution are examined, and are well-described by a maximum entropy principle for constrained circulation, energy, and angular momentum. The turbulent decay of the system is also examined, and a similarity decay law is proposed which incorporates the substantial enstrophy trapped in the metastable equilibrium. This law approaches Batchelor's t-2 self-similar decay in the limit of strong turbulence, and is verified in turbulent evolution in the electron plasma experiment.

  4. Depolarization due to beam-beam interaction in electron-positron linear colliders

    SciTech Connect

    Yokoya, K. ); Chen, P. )

    1989-05-05

    We investigate two major mechanisms which induce depolarization of electron beams during beam-beam interaction in linear colliders. These are the classical spin precession under the collective field of the oncoming beam, and the spin-flip effect from beamstrahlung. Analytic formulas are derived for estimating these depolarization effects. As examples, we estimate the depolarization in the Stanford Linear Collider (SLC) and a possible future TeV linear collider (TLC). The effects are found to be negligibly small for SLC and not very large for TLC.

  5. Upgrade of the electron beam ion trap in Shanghai

    SciTech Connect

    Lu, D.; Yang, Y.; Xiao, J.; Shen, Y.; Fu, Y.; Wei, B.; Yao, K.; Hutton, R.; Zou, Y.

    2014-09-15

    Over the last few years the Shanghai electron beam ion trap (EBIT) has been successfully redesigned and rebuilt. The original machine, developed under collaboration with the Shanghai Institute of Applied Physics, first produced an electron beam in 2005. It could be tuned with electron energies between 1 and 130 keV and beam current up to 160 mA. After several years of operation, it was found that several modifications for improvements were necessary to reach the goals of better electron optics, higher photon detection, and ion injection efficiencies, and more economical running costs. The upgraded Shanghai-EBIT is made almost entirely from Ti instead of stainless steel and achieves a vacuum of less than 10{sup −10} Torr, which helps to minimize the loss of highly changed ions through charge exchange. Meanwhile, a more compact structure and efficient cryogenic system, and excellent optical alignment have been of satisfactory. The magnetic field in the central trap region can reach up till 4.8 T with a uniformity of 2.77 × 10{sup −4}. So far the upgraded Shanghai-EBIT has been operated up to an electron energy of 151 keV and a beam current of up to 218 mA, although promotion to even higher energy is still in progress. Radiation from ions as highly charged as Xe{sup 53+,} {sup 54+} has been produced and the characterization of current density is estimated from the measured electron beam width.

  6. Thermal response of ceramic components during electron beam brazing

    SciTech Connect

    Voth, T.E.; Gianoulakis, S.E.; Halbleib, J.A.

    1996-03-01

    Ceramics are being used increasingly in applications where high temperatures are encountered such as automobile and gas turbine engines. However, the use of ceramics is limited by a lack of methods capable of producing strong, high temperature joints. This is because most ceramic-ceramic joining techniques, such as brazing, require that the entire assembly be exposed to high temperatures in order to assure that the braze material melts. Alternatively, localized heating using high energy electron beams may be used to selectively heat the braze material. In this work, high energy electron beam brazing of a ceramic part is modeled numerically. The part considered consists of a ceramic cylinder and disk between which is sandwiched an annular washer of braze material. An electron beam impinges on the disk, melting the braze metal. The resulting coupled electron and thermal transport equations are solved using Monte Carlo and finite element techniques. Results indicate that increased electron beam current decreases time to melt as well as required cooling time. Vacuum furnace brazing was also simulated and predicted results indicate increased processing times relative to electron beam brazing.

  7. Dosimetry of small fields for Therac 20 electron beams.

    PubMed

    Sharma, S C; Wilson, D L; Jose, B

    1984-01-01

    The Therac 20 medical linear accelerator produces electron beams of 6, 9, 13, 17, and 20 MeV. We measured depth dose, isodose curves, and output factors for small electron fields using an ionization chamber, film, and thermoluminescent dosimeters. Tables and graphs were generated from these measurements for accurate treatment planning of various blocked and open fields.

  8. Experimental Studies of Electrons in a Heavy-Ion Beam

    SciTech Connect

    Molvik, A W; Seidl, P A; Bieniosek, F M; Cohen, R H; Faltens, A; Friedman, A; Covo, M K; Lund, S M; Prost, L

    2004-06-23

    Electron cloud effects, ECEs, are normally a problem only in ring accelerators. However, heavy-ion induction linacs for inertial fusion energy have an economic incentive to fit beam tubes tightly to intense beams. This places them at risk from electron clouds produced by emission of electrons and gas from walls. We have measured electron and gas emission from 1 MeV K{sup +} impact on surfaces near grazing incidence on the High-Current Experiment (HCX) at LBNL. Electron emission coefficients reach *values of 130, whereas gas desorption coefficients are near 10{sup 4}. Mitigation techniques are being studied: A bead-blasted rough surface reduces electron emission by a factor of 10 and gas desorption by a factor of 2. Diagnostics are installed on HCX, between and within quadrupole magnets, to measure the beam halo loss, net charge and expelled ions, from which we infer gas density, electron trapping, and the effects of mitigation techniques. Here we discuss a new diagnostic technique that measures gas pressure and electron ionization rates within quadrupole magnets during the beam transit.

  9. Scattered electron beams shaped by a multileaf collimator

    NASA Astrophysics Data System (ADS)

    Moran, Jean Marie

    Recent developments in conformal radiation therapy have focused primarily on applying computer-controlled equipment and techniques to photon beams. Despite favorable characteristics of the dose fall-off with depth for electron beams, their application to conformal therapy has been limited. Factors such as geometrically limiting applicator systems, lack of automatic field shaping, and dose calculation model limitations must be addressed before routine clinical use of electron beams for conformal radiotherapy becomes common. This work evaluates dose characteristics and modeling of dose distributions and output factors for a system specifically designed for computer-controlled collimation of dual-foil scattered and scanned electron beams. Dose characteristics determined from measured depth dose curves and profiles were evaluated for multileaf- collimated and applicator-collimated beams produced by the dual-foil scattered gantry of a two-gantry racetrack microtron system. The resulting dose distributions and characteristics were used to evaluate and modify the existing 3-D electron pencil beam algorithm in UMPlan, the University of Michigan treatment planning system, to predict relative dose distributions for MLC-shaped fields. Output factors (dose of a field relative to that of a reference field) were measured, analyzed, and modeled for MLC-collimated rectangular and shaped fields. For output factor calculations, two models were evaluated: a pencil beam-derived model and an empirical edge model originally developed for photon dose calculations. The current work shows that the dosimetric characteristics of MLC and applicator-collimated beams of the racetrack microtron are similar once the collimation geometry is accounted for. The dosimetric characteristics are also consistent with those for other dual-foil scattered machines with applicator systems and earlier generation scanned beams collimated with trimmer bars. By accounting for collimation geometry, electron

  10. A Study of the Effect of Preschool Children's Participation in Sensorimotor Activities on Their Understanding of the Mechanical Equilibrium of a Balance Beam

    ERIC Educational Resources Information Center

    Hadzigeorgiou, Yannis; Anastasiou, Leonidas; Konsolas, Manos; Prevezanou, Barbara

    2009-01-01

    The purpose of this study was to investigate whether participation in sensorimotor activities by preschool children involving their own bodily balance while walking on a beam over the floor has an effect on their understanding of the mechanical equilibrium of a balance beam. The balance beam consisted of a horizontal stick balancing around its…

  11. Design of Electron-Beam Controlled Switches.

    DTIC Science & Technology

    1982-11-24

    atomic physics, cumulative heating in the switch, and switch e-beam driver under repetitive, long conduction time (with respect to the load pulse ... surface flashover switch,𔃿 (3) the thyratron,’ŕ (4) the high pressure spark gap, (5) the magnetic switch,19 󈧘 and (6) the EBCS. The ongoing research...for both the low pressure gas and surface flashover closing switches has yielded some encouraging results. The technology appears to be simple. At

  12. Adjustable stiffness of individual piezoelectric nanofibers by electron beam polarization

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Li, Anton; Yao, Nan; Shi, Yong

    2011-11-01

    We present a method to adjust the stiffness of individual piezoelectric nanofiber by electron beam induced polarization under an in situ scanning electron microscopy. The lead zirconate titanate (PZT) nanofibers were fabricated by an electrospinning process. The Young's modulus was calculated from the resonant frequency excited by an oscillating electric field applied through a nanomanipulator. The stiffness can be adjusted up to 75% by induced polarization under the exposure of an electron beam to control the domain boundaries in single PZT nanofibers. Splitting effect of the resonant frequencies was observed due to anisotropic stiffness in polarized PZT nanofibers.

  13. Dynamics of a high-current relativistic electron beam

    SciTech Connect

    Strelkov, P. S.; Tarakanov, V. P.; Ivanov, I. E. Shumeiko, D. V.

    2015-06-15

    The dynamics of a high-current relativistic electron beam is studied experimentally and by numerical simulation. The beam is formed in a magnetically insulated diode with a transverse-blade explosive-emission cathode. It is found experimentally that the radius of a 500-keV beam with a current of 2 kA and duration of 500 ns decreases with time during the beam current pulse. The same effect was observed in numerical simulations. This effect is explained by a change in the shape of the cathode plasma during the current pulse, which, according to calculations, leads to a change in the beam parameters, such as the electron pitch angle and the spread over the longitudinal electron momentum. These parameters are hard to measure experimentally; however, the time evolution of the radial profile of the beam current density, which can be measured reliably, coincides with the simulation results. This allows one to expect that the behavior of the other beam parameters also agrees with numerical simulations.

  14. Coulomb repulsion and the electron beam directed energy weapon

    NASA Astrophysics Data System (ADS)

    Retsky, Michael W.

    2004-09-01

    Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into small spots at large distances from defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Based on estimates, the nonreversible terms should be small - of the order of 0.1 mm. If this is true, it is possible to design a practical electron beam directed weapon not limited by Coulomb repulsion.

  15. Characteristics of scattered electron beams shaped with a multileaf collimator.

    PubMed

    Moran, J M; Martel, M K; Bruinvis, I A; Fraass, B A

    1997-09-01

    Characteristics of dual-foil scattered electron beams shaped with a multileaf collimator (MLC) (instead of an applicator system) were studied. The electron beams, with energies between 10 and 25 MeV, were produced by a racetrack microtron using a dual-foil scattering system. For a range of field sizes, depth dose curves, profiles, penumbra width, angular spread in air, and effective and virtual source positions were compared. Measurements were made when the MLC alone provided collimation and when an applicator provided collimation. Identical penumbra widths were obtained at a source-to-surface distance of 85 cm for the MLC and 110 cm for the applicator. The MLC-shaped beams had characteristics similar to other machines which use trimmers or applicators to collimate scanned or scattered electron beams. Values of the effective source position and the angular spread parameter for the MLC beams were similar to those of the dual-foil scattered beams of the Varian Clinac 2100 CD and the scanned beams of the Sagittaire linear accelerators. A model, based on Fermi-Eyges multiple scattering theory, was adapted and applied successfully to predict penumbra width as a function of collimator-surface distance.

  16. Electron Beam Diagnostics Of The JLAB UV FEL

    SciTech Connect

    Evtushenko, Pavel; Benson, Stephen; Biallas, George; Coleman, James; Dickover, Cody; Douglas, David; Marchlik, Matthew; Sexton, Daniel; Tennant, Christopher

    2011-03-01

    In this contribution we describe various systems and aspects of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line at the existing 10 kW IR Upgrade FEL. Here, we describe a set of the following systems. A combination of OTR and phosphor viewers is used for measurements of the transverse beam profile, transverse emittance, and Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurement system is used to set up bunch compression in an optimal way, such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of diagnostic systems made a significant contribution in achieving first lasing of the FEL after only about 60 hours of beam operation.

  17. Ignition of beam plasma discharge in the electron beam experiment in space

    NASA Technical Reports Server (NTRS)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Roberts, W. T.; Taylor, W. W. L.

    1985-01-01

    An ignition of beam plasma discharge (BPD) in space was observed in a neutral gas-electron beam interaction experiment by Space Shuttle/Spacelab-1 in 1983. An electron beam of 8 kV 100 mA was injected into a high dense nitrogen gas cloud of 10 to the 23rd molecules which was released during 100 msec from the Orbiter. The appearance of the beam and its surroundings observed by a low-light-level TV camera showed a local ignition of the beam plasma discharge in the gas cloud. The enhanced plasma production, generation of auroral emission, and associated wave emission were also detected by onboard diagnostic instruments.

  18. Carbon-nanotube electron-beam (C-beam) crystallization technique for silicon TFTs

    NASA Astrophysics Data System (ADS)

    Lee, Su Woong; Kang, Jung Su; Park, Kyu Chang

    2016-02-01

    We introduced a carbon-nanotube (CNT) electron beam (C-beam) for thin film crystallization and thin film transistor (TFT) applications. As a source of electron emission, a CNT emitter which had been grown on a silicon wafer with a resist-assisted patterning (RAP) process was used. By using the C-beam exposure, we successfully crystallized a silicon thin film that had nano-sized crystalline grains. The distribution of crystalline grain size was about 10 ˜ 30 nm. This nanocrystalline silicon thin film definitely had three crystalline directions which are (111), (220) and (311), respectively. The silicon TFTs crystallized by using a C-beam exposure showed a field effect mobility of 20 cm2/Vs and an on/off ratio of more than 107. The C-beam exposure can modify the bonding network of amorphous silicon with its proper energy.

  19. Dual scattering foil design for poly-energetic electron beams.

    PubMed

    Kainz, K K; Antolak, J A; Almond, P R; Bloch, C D; Hogstrom, K R

    2005-03-07

    The laser wakefield acceleration (LWFA) mechanism can accelerate electrons to energies within the 6-20 MeV range desired for therapy application. However, the energy spectrum of LWFA-generated electrons is broad, on the order of tens of MeV. Using existing laser technology, the therapeutic beam might require a significant energy spread to achieve clinically acceptable dose rates. The purpose of this work was to test the assumption that a scattering foil system designed for a mono-energetic beam would be suitable for a poly-energetic beam with a significant energy spread. Dual scattering foil systems were designed for mono-energetic beams using an existing analytical formalism based on Gaussian multiple-Coulomb scattering theory. The design criterion was to create a flat beam that would be suitable for fields up to 25 x 25 cm2 at 100 cm from the primary scattering foil. Radial planar fluence profiles for poly-energetic beams with energy spreads ranging from 0.5 MeV to 6.5 MeV were calculated using two methods: (a) analytically by summing beam profiles for a range of mono-energetic beams through the scattering foil system, and (b) by Monte Carlo using the EGS/BEAM code. The analytic calculations facilitated fine adjustments to the foil design, and the Monte Carlo calculations enabled us to verify the results of the analytic calculation and to determine the phase-space characteristics of the broadened beam. Results showed that the flatness of the scattered beam is fairly insensitive to the width of the input energy spectrum. Also, results showed that dose calculated by the analytical and Monte Carlo methods agreed very well in the central portion of the beam. Outside the useable field area, the differences between the analytical and Monte Carlo results were small but significant, possibly due to the small angle approximation. However, these did not affect the conclusion that a scattering foil system designed for a mono-energetic beam will be suitable for a poly

  20. Influence of static electron beam`s self-fields on the cyclotron-undulator resonance

    SciTech Connect

    Rozanov, N.E.; Golub, Yu.Ya. |

    1995-12-31

    When undulators with a leading magnetic field B are used, the regime of double resonance is possible in which an undulator period is equal to an electron cyclotron wavelength. In the vicinity of this resonance an amplitude of particle oscillations in the undulator strongly depends on a difference between B and a resonant value of the leading magnetic field. Consequently, it is important to investigate a role of self-fields of the electron beam, in particular, due to its influence on the electron cyclotron wavelength. At the paper analytically and by numerical simulation the influence of the static fields of the annular electron beam on its dynamics in the axisymmetrical magnetic undulator with the leading magnetic field in the vicinity of the cyclotron-undulator resonance is investigated. It is shown that the value of the resonant magnetic field is changed with the rise of beam`s current. A shift of the resonant magnetic field may be both to larger values of B and to smaller ones, when different values of beam and waveguide radii, beam energy and undulator period are considered. A width of the resonance (on B - scale) is increased with the beam current.

  1. Electron Beam/Converter Target Interactions in Radiographic Accelerators

    SciTech Connect

    McCarrick, J; Caporaso, G; Chambers, F; Chen, Y-J; Falabella, S; Goldin, F; Guethlein, G; Ho, D; Richardson, R; Weir, J

    2003-05-27

    Linear induction accelerators used in X-ray radiography have single-pulse parameters of the order 20 MeV of electron beam energy, 2 kA of beam current, pulse lengths of 50-100 ns, and spot sizes of 1-2 mm. The thermal energy deposited in a bremsstrahlung converter target made of tantalum from such a pulse is {approx}80 kJ/cc, more than enough to bring the target material to a partially ionized state. The tail end of a single beam pulse, or any subsequent pulse in a multi-pulse train, undergoes a number of interactions with the target that can affect beam transport and radiographic performance. Positive ions extracted from the target plasma by the electron beam space charge can affect the beam focus and centroid stability. As the target expands on the inter-pulse time scale, the integrated line density of material decreases, eventually affecting the X-ray output of the system. If the target plume becomes sufficiently large, beam transport through it is affected by macroscopic charge and current neutralization effects and microscopic beam/plasma instability mechanisms. We will present a survey of some of these interactions, as well as some results of an extensive experimental and theoretical campaign to understand the practical amelioration of these effects, carried out at the ETA-II accelerator facility at the Lawrence Livermore National Laboratory.

  2. Experimental Time Resolved Electron Beam Temperature Measurements Using Bremsstrahlung Diagnostics

    SciTech Connect

    Menge, P.R.; Maenchen, J.E.; Mazarakis, M.G.; Rosenthal, S.E.

    1999-06-25

    Electron beam temperature, {beta}{perpendicular} (= v{perpendicular}/v), is important to control for the development of high dose flash radiographic bremsstrahlung sources. At high voltage (> 5 MV) increasing electron beam temperature has a serious deleterious effect on dose production. The average and time resolved behavior of beam temperature was measured during radiographic experiments on the HERMES III accelerator (10 MV, 50 kA, 70 ns). A linear array of thermoluminescent dosimeters (TLDs) were used to estimate the time integrated average of beam temperature. On and off-axis photoconducting diamond (PCD) detectors were used to measure the time resolved bremsstrahlung dose rate, which is dependent on beam energy and temperature. The beam temperature can be determined by correlating PCD response with accelerator voltage and current and also by analyzing the ratio of PCD amplitudes on and off axis. This ratio is insensitive to voltage and current and thus, is more reliable than utilizing absolute dose rate. The data is unfolded using comparisons with Monte Carlo simulations to obtain absolute beam temperatures. The data taken on HERMES III show abrupt increases in {beta}{perpendicular} midway through the pulse indicating rapid onset of beam instability.

  3. Pulsed electron beam propagation in argon and nitrogen gas mixture

    SciTech Connect

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Zhirkov, I. S.

    2015-10-15

    The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N{sub 2}). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively.

  4. Uniqueness of the equilibrium of an electron plasma on magnetic surfaces

    SciTech Connect

    Durand de Gevigney, Benoit

    2011-01-15

    The equilibrium of an electron plasma on magnetic surfaces is governed by a Poisson-Boltzmann equation. The electrons follow a Boltzmann distribution on each surface and the charge density depends exponentially on the electric potential. It is a well-known property that the classical Poisson's equation, for which the charge density is an independent parameter, possesses a unique solution provided suitable boundary conditions are given. Here we show that the Poisson-Boltzmann equation describing electron plasmas on magnetic surfaces also has a unique solution.

  5. Equilibrium polymerization of acenaphthylene and its copolymerizations with electron-accepting vinyl monomers

    SciTech Connect

    Iwatsuki, Shouji; Kubo, Masataka; Iwayama, Hiroaki

    1993-12-20

    Radical polymerization kinetics of acenaphthylene in toluene using 2,2{prime}-azobis (isobutyronitrile) (AIBN) as an initiator was investigated revealing an equilibrium polymerization. The values of monomer concentration at equilibrium were determined to be between 1.3 and 3.3 mol/L for a temperature range of 50--70 C. The thermodynamics parameters were determined and showed an enthalpy change of {delta}H = {minus}43 kJ/mol and an entropy change of {delta}S ={minus}98J/K {center_dot} mol. Furthermore, copolymerization of acenaphthylene with electron-accepting vinyl monomers such as methyl methacrylate (MMA) and acrylonitrile (AN) were carried out and showed a change from random to alternating copolymerization as the acenaphthylene concentration decreased. This change in mechanism is rationally explained in terms of the equilibrium polymerization of acenaphthylene.

  6. Electron Beam Alignment Strategy in the LCLS Undulators

    SciTech Connect

    Nuhn, H.-D.; Emma, P.J.; Gassner, G.L.; LeCocq, C.M.; Peters, E.; Ruland, R.E.; /SLAC

    2007-01-03

    The x-ray FEL process puts very tight tolerances on the straightness of the electron beam trajectory (2 {micro}m rms) through the LCLS undulator system. Tight but less stringent tolerances of 80 {micro}m rms vertical and 140 {micro}m rms horizontally are to be met for the placement of the individual undulator segments with respect to the beam axis. The tolerances for electron beam straightness can only be met through beam-based alignment (BBA) based on electron energy variations. Conventional alignment will set the start conditions for BBA. Precision-fiducialization of components mounted on remotely adjustable girders and the use of beam-finder wires (BFW) will satisfy placement tolerances. Girder movement due to ground motion and temperature changes will be monitored continuously by an alignment monitoring system (ADS) and remotely corrected. This stabilization of components as well as the monitoring and correction of the electron beam trajectory based on BPMs and correctors will increase the time between BBA applications. Undulator segments will be periodically removed from the undulator Hall and measured to monitor radiation damage and other effects that might degrade undulator tuning.

  7. Improvement of electron beam shape control in radiation processing

    NASA Astrophysics Data System (ADS)

    Strasser, A.; Fang, R.; Kuntz, F.

    1994-05-01

    The development of radiation processing using electron accelerators requires good control of the treatment parameters to improve the dosimetry quality. Especially, the analysis of the shape of the scanned electron beam that interacts with the product, is of prime necessity. A Multiwire Beam Shape Analyser (MBSA) has been developed by the AERIAL Laboratory in order to insure good monitoring of the scanning length and uniformity. This device consists of an aluminum beam-stop covered with a mesh of individually insulated stainless steel wires, placed under the scanning cone. The current generated by the impact of the electron beam on each wire is converted into voltage. After pulse shaping and multiplexing of the different channels, the beam profile can be displayed on an oscilloscope or on a PC screen. A prototype is now operating on an experimental irradiation plant based on a 2.5 MeV /300 W Van de Graaff electron accelerator. It allows almost continuous visualization of the beam profile (between two conveyor passes) and its response was compared to classical film dosimeters (Gafchromic, FWT 60.00). Considering FWHM and homogeneous treatment regions of the profiles, MBSA and the dosimeters give similar responses and variations remain lower than ± 12%. The acquisition of an electrical signal corresponding to the beam profile in air constitutes the original aspect of the MBSA and is in keeping with the general pattern of continuous control and automation of the irradiation processes. Hereafter, much work has to be done to adapt this device to an industrial use (higher energy, high power electron beams, non-destructive measurements…).

  8. Return Current Electron Beams and Their Generation of "Raman" Scattering

    NASA Astrophysics Data System (ADS)

    Simon, A.

    1998-11-01

    For some years, we(A. Simon and R. W. Short, Phys. Rev. Lett. 53), 1912 (1984). have proposed that the only reasonable explanation for many of the observations of "Raman" scattering is the presence of an electron beam in the plasma. (The beam creates a bump-on-tail instability.) Two major objections to this picture have been observation of Raman when no n_c/4 surface was present, with no likely source for the electron beam, and the necessity for the initially outward directed beam to bounce once to create the proper waves. Now new observations on LLE's OMEGA(R. Petrasso et al), this conference. and at LULI(C. Labaune et al)., Phys. Plasma 5, 234 (1998). have suggested a new origin for the electron beam. This new scenario answers the previous objections, maintains electron beams as the explanation of the older experiments, and may clear up puzzling observations that have remained unexplained. The new scenario is based on two assumptions: (1) High positive potentials develop in target plasmas during their creation. (2) A high-intensity laser beam initiates spark discharges from nearby surfaces to the target plasma. The resulting return current of electrons should be much more delta-like, is initially inwardly directed, and no longer requires the continued presence of a n_c/4 surface. Scattering of the interaction beam from the BOT waves yields the observed Raman signal. Experimental observations that support this picture will be cited. ``Pulsation'' of the scattering and broadband ``flashes'' are a natural part of this scenario. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  9. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    SciTech Connect

    Sydorenko, D.; Kaganovich, I. D.; Chen, L.; Ventzek, P. L. G.

    2015-12-15

    Generation of anomalously energetic suprathermal electrons was observed in simulation of a high-voltage dc discharge with electron emission from the cathode. An electron beam produced by the emission interacts with the nonuniform plasma in the discharge via a two-stream instability. The energy transfer from the beam to the plasma electrons is ensured by the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The waves with short wavelength near the anode accelerate plasma bulk electrons to suprathermal energies. The sheath near the anode reflects some of the accelerated electrons back into the plasma. These electrons travel through the plasma, reflect near the cathode, and enter the accelerating area again but with a higher energy than before. Such particles are accelerated to energies much higher than after the first acceleration. This mechanism plays a role in explaining earlier experimental observations of energetic suprathermal electrons in similar discharges.

  10. Electron-beam-driven RI separator for SCRIT (ERIS) at RIKEN RI beam factory

    NASA Astrophysics Data System (ADS)

    Ohnishi, T.; Ichikawa, S.; Koizumi, K.; Kurita, K.; Miyashita, Y.; Ogawara, R.; Tamaki, S.; Togasaki, M.; Wakasugi, M.

    2013-12-01

    We constructed a radioactive isotope (RI) separator named ERIS (electron-beam-driven RI separator for SCRIT) for the SCRIT (Self-Confinement RI Target) electron scattering facility at RIKEN RI Beam Factory (RIBF). In ERIS, production rate of fission products in the photofission of uranium is estimated to be 2.2 ×1011 fissions/s with 30 g of uranium and a 1-kW electron beam. During the commissioning of ERIS, the mass resolution and overall efficiency, including ionization, extraction, and transmission, were found to be 1660 and 21%, respectively, using natural xenon gas. The preparation of uranium carbide (UC2) RI production targets is described from which a 132Sn beam was successfully separated in our first attempt at RI production.

  11. Optimal beam pattern to maximize inclusion residence time in an electron beam melting hearth

    SciTech Connect

    Powell, A.; Pal, U.; Avyle, J. van den

    1997-02-01

    Approximate probabilities of inclusion survival through an electron beam melting hearth are computed from nitride dissolution rates, flotation velocities, and residence times. Dissolution rates were determined by measuring shrinkage rates of pure TiN and nitrided sponge in small pools of molten titanium in an electron beam melting hearth. Flotation velocities were calculated using correlations for fluid flow around spheres, and show that particles sink or float unless their densities are extremely close to that of molten titanium. Flow field characteristics which lead to effective inclusion removal are discussed in terms of heat flux pattern required to produce them, based on the electron beam`s unique ability to impart a nearly arbitrary heat flux pattern to the melt surface.

  12. Curing Composite Materials Using Lower-Energy Electron Beams

    NASA Technical Reports Server (NTRS)

    Byrne, Catherine A.; Bykanov, Alexander

    2004-01-01

    In an improved method of fabricating composite-material structures by laying up prepreg tapes (tapes of fiber reinforcement impregnated by uncured matrix materials) and then curing them, one cures the layups by use of beams of electrons having kinetic energies in the range of 200 to 300 keV. In contrast, in a prior method, one used electron beams characterized by kinetic energies up to 20 MeV. The improved method was first suggested by an Italian group in 1993, but had not been demonstrated until recently. With respect to both the prior method and the present improved method, the impetus for the use of electron- beam curing is a desire to avoid the high costs of autoclaves large enough to effect thermal curing of large composite-material structures. Unfortunately, in the prior method, the advantages of electron-beam curing are offset by the need for special walls and ceilings on curing chambers to shield personnel from x rays generated by impacts of energetic electrons. These shields must be thick [typically 2 to 3 ft (about 0.6 to 0.9 m) if made of concrete] and are therefore expensive. They also make it difficult to bring large structures into and out of the curing chambers. Currently, all major companies that fabricate composite-material spacecraft and aircraft structures form their layups by use of automated tape placement (ATP) machines. In the present improved method, an electron-beam gun is attached to an ATP head and used to irradiate the tape as it is pressed onto the workpiece. The electron kinetic energy between 200 and 300 keV is sufficient for penetration of the ply being laid plus one or two of the plies underneath it. Provided that the electron-beam gun is properly positioned, it is possible to administer the required electron dose and, at the same time, to protect personnel with less shielding than is needed in the prior method. Adequate shielding can be provided by concrete walls 6 ft (approximately equal to 1.8 m) high and 16 in. (approximately

  13. Research on Intense Electron Beams and Applications.

    DTIC Science & Technology

    1984-07-01

    controlled fusion research devices10 - 12 and other machines . 13 In recent times there has been renewed interest in high power, high efficiency microwave...7, 22 (1960). 16. 0. Buneman, J. Electron. Control 3, 1,507 (1957). 17. G. DOhler, submitted to IEEE Trans. Electron Devices. 18. Y.Y. Lau and D...with respect to h when ways positive. h - 1/vs Thus. according to Eqs (1) and (5). the £ 140. Buneman. J. Electron. Control 3. 507 (1957). layer is most

  14. Optimization of Compton Source Performance through Electron Beam Shaping

    SciTech Connect

    Malyzhenkov, Alexander; Yampolsky, Nikolai

    2016-09-26

    We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a way so that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary.

  15. Flat-Lens Focusing of Electron Beams in Graphene

    PubMed Central

    Tang, Yang; Cao, Xiyuan; Guo, Ran; Zhang, Yanyan; Che, Zhiyuan; Yannick, Fouodji T.; Zhang, Weiping; Du, Junjie

    2016-01-01

    Coupling electron beams carrying information into electronic units is fundamental in microelectronics. This requires precision manipulation of electron beams through a coupler with a good focusing ability. In graphene, the focusing of wide electron beams has been successfully demonstrated by a circular p-n junction. However, it is not favorable for information coupling since the focal length is so small that the focal spot locates inside the circular gated region, rather than in the background region. Here, we demonstrate that an array of gate-defined quantum dots, which has gradually changing lattice spacing in the direction transverse to propagation, can focus electrons outside itself, providing a possibility to make a coupler in graphene. The focusing effect can be understood as due to the gradient change of effective refractive indices, which are defined by the local energy band in a periodic potential. The strong focusing can be achieved by suitably choosing the lattice gradient and the layer number in the incident direction, offering an effective solution to precision manipulation of electron beams with wide electron energy range and high angular tolerance. PMID:27628099

  16. Optimization of compton source performance through electron beam shaping

    NASA Astrophysics Data System (ADS)

    Malyzhenkov, Alexander; Yampolsky, Nikolai

    2017-03-01

    We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality, since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6D electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized, then, if the electron phase space is transformed in a way such that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6D photon phase space distribution), and derive it for the ICS source when the electron and laser rms matrices are arbitrary.

  17. Electrostatic ion beam trap for electron collision studies

    SciTech Connect

    Heber, O.; Witte, P.D.; Diner, A.; Bhushan, K.G.; Strasser, D.; Toker, Y.; Rappaport, M.L.; Ben-Itzhak, I.; Altstein, N.; Schwalm, D.; Wolf, A.; Zajfman, D.

    2005-01-01

    We describe a system combining an ion beam trap and a low energy electron target in which the interaction between electrons and vibrationally cold molecular ions and clusters can be studied. The entire system uses only electrostatic fields for both trapping and focusing, thus being able to store particles without a mass limit. Preliminary results for the electron impact neutralization of C{sub 2}{sup -} ions and aluminum clusters are presented.

  18. Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam

    SciTech Connect

    Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Yu, Jennifer W.

    2008-09-02

    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 velocity, for a beam moving at v~;;c. Details of the dynamics of the resonance are described.

  19. Microwave Emission From Relativistic Electron Beams

    DTIC Science & Technology

    1993-04-12

    9 Effect of electron prebunching on the radiation growth rate in a collective...Appendix 1) we have ob- served profile modifications caused by the free electron laser interaction. The modifications are a combination of two effects ...experiment to continue for a period of 6-12 months. It is complementary to the studies being carried out at Columbia University’ where multimode effects are

  20. Effect of secondary ions on the electron beam optics in the Recycler Electron Cooler

    SciTech Connect

    Shemyakin, A.; Prost, L.; Saewert, G.; /Fermilab

    2010-05-01

    Antiprotons in Fermilab's Recycler ring are cooled by a 4.3 MeV, 0.1-0.5 A DC electron beam (as well as by a stochastic cooling system). The unique combination of the relativistic energy ({gamma} = 9.49), an Ampere-range DC beam, and a relatively weak focusing makes the cooling efficiency particularly sensitive to ion neutralization. A capability to clear ions was recently implemented by way of interrupting the electron beam for 1-30 {micro}s with a repetition rate of up to 40 Hz. The cooling properties of the electron beam were analyzed with drag rate measurements and showed that accumulated ions significantly affect the beam optics. For a beam current of 0.3 A, the longitudinal cooling rate was increased by factor of {approx}2 when ions were removed.

  1. Electron beam-assisted healing of nanopores in magnesium alloys

    PubMed Central

    Zheng, He; Liu, Yu; Cao, Fan; Wu, Shujing; Jia, Shuangfeng; Cao, Ajing; Zhao, Dongshan; Wang, Jianbo

    2013-01-01

    Nanopore-based sensing has emerged as a promising candidate for affordable and powerful DNA sequencing technologies. Herein, we demonstrate that nanopores can be successfully fabricated in Mg alloys via focused electron beam (e-beam) technology. Employing in situ high-resolution transmission electron microscopy techniques, we obtained unambiguous evidence that layer-by-layer growth of atomic planes at the nanopore periphery occurs when the e-beam is spread out, leading to the shrinkage and eventual disappearance of nanopores. The proposed healing process was attributed to the e-beam-induced anisotropic diffusion of Mg atoms in the vicinity of nanopore edges. A plausible diffusion mechanism that describes the observed phenomena is discussed. Our results constitute the first experimental investigation of nanopores in Mg alloys. Direct evidence of the healing process has advanced our fundamental understanding of surface science, which is of great practical importance for many technological applications, including thin film deposition and surface nanopatterning. PMID:23719630

  2. Two-dimensional electron beam charging model for polymer films

    NASA Technical Reports Server (NTRS)

    Reeves, R. D.; Balmain, K. G.

    1981-01-01

    A two-dimensional model is developed to describe the charging of strips of thin polymer films above a grounded substrate exposed to a uniform mono-energetic electron beam. The study is motivated by the observed anomalous behavior of geosynchronous satellites, which has been attributed to differential charging of the satellite surfaces exposed to magnetospheric electrons. Surface and bulk electric fields are calcuated at steady state in order to identify regions of high electrical stress, with emphasis on behavior near the material's edge. The model is used to study the effects of some of the experimental parameters, notably beam energy, beam angle of incidence, beam current density, material thickness and material width. Also examined are the consequences of a central gap in the material and a discontinuity in the material thickness.

  3. Tomographic determination of the power distribution in electron beams

    DOEpatents

    Teruya, Alan T.; Elmer, John W.

    1996-01-01

    A tomographic technique for determining the power distribution of an electron beam using electron beam profile data acquired from a modified Faraday cup to create an image of the current density in high and low power beams. A refractory metal disk with a number of radially extending slits is placed above a Faraday cup. The beam is swept in a circular pattern so that its path crosses each slit in a perpendicular manner, thus acquiring all the data needed for a reconstruction in one circular sweep. Also, a single computer is used to generate the signals actuating the sweep, to acquire that data, and to do the reconstruction, thus reducing the time and equipment necessary to complete the process.

  4. Tomographic determination of the power distribution in electron beams

    DOEpatents

    Teruya, A.T.; Elmer, J.W.

    1996-12-10

    A tomographic technique for determining the power distribution of an electron beam using electron beam profile data acquired from a modified Faraday cup to create an image of the current density in high and low power beams is disclosed. A refractory metal disk with a number of radially extending slits is placed above a Faraday cup. The beam is swept in a circular pattern so that its path crosses each slit in a perpendicular manner, thus acquiring all the data needed for a reconstruction in one circular sweep. Also, a single computer is used to generate the signals actuating the sweep, to acquire that data, and to do the reconstruction, thus reducing the time and equipment necessary to complete the process. 4 figs.

  5. Simulation Of Electron Cloud Effects On Electron Beam At ERL With Pipelined QuickPIC

    SciTech Connect

    Feng, B.; Muggli, P.; Huang, C.; Decyk, V.; Mori, W. B.; Hoffstaetter, G. H.; Katsouleas, T.

    2009-01-22

    With the successful implementation of pipelining algorithm to the QuickPIC code, the number of processors used is increased by 2 to 3 orders of magnitude, and the speed of the simulation is improved by a similar factor. The pipelined QuickPIC is used to simulate the electron cloud effect on electron beam in the Cornell Energy Recovery Linac (ERL) due to extremely small emittance and high peak currents anticipated in the machine. A tune shift is found due to electron cloud on electron beams, which is of equal magnitude to that on positron beams but in an opposite direction; however, emittance growth of the electron beam in an electron cloud is not observed for ERL parameters.

  6. Analysis of Electron Beam Damage of Crystalline Pharmaceutical Materials by Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    S'ari, M.; Cattle, J.; Hondow, N.; Blade, H.; Cosgrove, S.; Brydson, R. M.; Brown, A. P.

    2015-10-01

    We have studied the impact of transmission electron microscopy (TEM) and low dose electron diffraction on ten different crystalline pharmaceutical compounds, covering a diverse chemical space and with differing physical properties. The aim was to establish if particular chemical moieties were more susceptible to damage within the electron beam. We have measured crystalline diffraction patterns for each and indexed nine out of ten of them. Characteristic electron dosages are reported for each material, with no apparent correlation between chemical structure and stability within the electron beam. Such low dose electron diffraction protocols are suitable for the study of pharmaceutical compounds.

  7. Electron beam assisted field evaporation of insulating nanowires/tubes

    SciTech Connect

    Blanchard, N. P. Niguès, A.; Choueib, M.; Perisanu, S.; Ayari, A.; Poncharal, P.; Purcell, S. T.; Siria, A.; Vincent, P.

    2015-05-11

    We demonstrate field evaporation of insulating materials, specifically BN nanotubes and undoped Si nanowires, assisted by a convergent electron beam. Electron irradiation leads to positive charging at the nano-object's apex and to an important increase of the local electric field thus inducing field evaporation. Experiments performed both in a transmission electron microscope and in a scanning electron microscope are presented. This technique permits the selective evaporation of individual nanowires in complex materials. Electron assisted field evaporation could be an interesting alternative or complementary to laser induced field desorption used in atom probe tomography of insulating materials.

  8. Transmission of High-Power Electron Beams Through Small Apertures

    SciTech Connect

    Tschalaer, Christoph; Alarcon, Ricardo O.; Balascuta, S.; Benson, Stephen V.; Bertozzi, William; Boyce, James R.; Cowan, Ray Franklin; Douglas, David R.; Evtushenko, Pavel; Fisher, Peter H.; Ihloff, Ernest E.; Kalantarians, Narbe; Kelleher, Aidan Michael; Legg, Robert A.; Milner, Richard; Neil, George R.; Ou, Longwu; Schmookler, Barak Abraham; Tennant, Christopher D.; Williams, Gwyn P.; Zhang, Shukui

    2013-11-01

    Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 hour continuous run.

  9. Wave-Particle Interactions on Relativistic Electron Beams.

    DTIC Science & Technology

    1983-10-20

    beam. Moreover, as we shall discuss presently, the axial magnetic field can introduce a number of physical features not present when this field is absent...Collective Free Electron Laser in Uniform Magnetic Field," A. Fruchtman and L. Friedland, IEEE J. Quantum Elec- tronics QE- 19 , 327 (1983). Most of the...transition, as predicted in paper #2. Since • the work reported in paper #3, the Hebrew University group has continued its work on beam diagnostics for

  10. Modulation of continuous electron beams in plasma wake-fields

    SciTech Connect

    Rosenzweig, J.B.

    1988-09-08

    In this paper we discuss the interaction of a continuous electron beam with wake-field generated plasma waves. Using a one-dimensional two fluid model, a fully nonlinear analytical description of the interaction is obtained. The phenomena of continuous beam modulation and wave period shortening are discussed. The relationship between these effects and the two-stream instability is also examined. 12 refs., 1 fig.

  11. Heat extraction from targets in high current electron beams

    NASA Astrophysics Data System (ADS)

    Bubb, Ernest; Altemus, Rosemary; McCarthy, James; Biron, Don

    1982-12-01

    Various aspects of heat extraction from targets in high current electron beams are examined, among which are the dependences on boundary temperature, beam current density, and convective effects from an ambient gaseous environment. The design of a cooling system which extracts heat by forcing hydrogen (or helium) gas at a pressure of several Torr at near sonic velocities across a target surface is described. Boundary layer theory calculations and empirical measurements of the average heat transfer coefficient for the system are presented.

  12. Efficient Injection of Electron Beams into Magnetic Guide Fields

    SciTech Connect

    Chorny, V.; Cooperstein, G.; Dubyna, V.; Frolov, O.; Harper-Slaboszewicz, V.; Hinshelwood, D.; Schneider, R.; Solovyov, V.; Tsepilov, H.; Vitkovitsky, I.; Ware, K,

    1999-06-08

    Preliminary experimental and modeling study of injection and transport of high current electron beams in current-neutralized background gas has been performed. Initial analysis of the results indicates that high current triaxial ring diode operates very reproducibly in the pinch mode. High current density beam can be injected efficiently into the drift region, using azimuthal guide field with reduced intensity near the injection region. This was shown to improve the effectiveness of capturing the beam for the transport. The transport length was insufficient to measure losses, such as would arise from scattering with the background gas.

  13. Emission of an intense electron beam from a ceramic honeycomb

    NASA Astrophysics Data System (ADS)

    Friedman, M.; Myers, M.; Hegeler, F.; Swanekamp, S. B.; Sethian, J. D.; Ludeking, L.

    2003-01-01

    Inserting a slab of honeycomb ceramic in front of the emitting surface of a large-area cathode improves the electron beam emission uniformity, decreases the beam current rise and fall times, and maintains a more constant diode impedance. Moreover, changing the cathode material from velvet to carbon fiber achieved a more robust cathode that starts to emit at a higher electric field without a degradation in beam uniformity. In addition, an 80% reduction in the postshot diode pressure was also observed when gamma alumina was deposited on the ceramic. A possible explanation is that reabsorption and recycling of adsorbed gases takes place.

  14. A method of forming a high-quality electron beam for free electron masers

    SciTech Connect

    Samsonov, S.V.; Bratman, V.L.; Manuilov, V.N.

    1995-12-31

    A large number of electron microwave devices require initially rectilinear high-quality electron beams for effective operation. In FEMS such beams are pumped up to sufficiently high operating-oscillation velocity and small initial particle oscillations (cyclotron oscillations if the beam is focused by an axial magnetic field) can lead to a rather large transverse velocity spread and, correspondingly, axial velocity spread. Thus, an acute problem for these devices (essentially more important than for Cherenkov-type devices) is the formation of a beam in which electrons initially move along the axis with minimum oscillations. A new method to form such a beam by a two-electrode axially-symmetrical gun of simple configuration immersed in a uniform axial magnetic field is discussed in this paper. This method allows to improve the quality of an electron beam passing through a narrow anode outlet. It is well-known that the anode aperture acts as an electrostatic lens and disperses the electron beam. In the presence of an axial magnetic field this unwanted dispersing action can be compensated simultaneously for all electrons of the paraxial electron beam by means of a magnetic field generated by a small additional coil placed down-stream from the anode aperture. If the coil length is equal to half the electron Larmor step, then the action of the border cod fields comes to two kicks which, being correctly phased, compensate the spurious rotary electron velocities. Computer simulations using the EPOSR-code intended for the calculation of electron guns both for the temperature- and space-charge-limited regimes prove the effectiveness of this method. In particular, for a version of field-emission gun the correcting coil reduces about five times the maximum transverse velocity in the beam. Positive effect from applying this method was proved at a realization of a high-efficiency CARM-oscillator.

  15. Time-Resolved Photoemission of Correlated Electrons Driven Out of Equilibrium

    SciTech Connect

    Moritz, B.; Devereaux, T.P.; Freericks, J.K.; /Georgetown U.

    2010-02-15

    We describe the temporal evolution of the time-resolved photoemission response of the spinless Falicov-Kimball model driven out of equilibrium by strong, applied fields. The model is one of the few possessing a metal-insulator transition and admitting an exact solution in the time domain. The nonequilibrium dynamics, evaluated using an extension of dynamical mean-field theory, show how the driven system differs from two common viewpoints - a quasi-equilibrium system at an elevated, effective temperature (the 'hot' electron model) or a rapid interaction quench ('melting' of the Mott gap) - due to the rearrangement of electronic states and redistribution of spectral weight. The results demonstrate the inherent trade-off between energy and time resolution accompanying the finite width probe-pulses, characteristic of those employed in pump-probe, time-domain experiments, which can be used to focus attention on different aspects of the dynamics near the transition.

  16. Single Crystal Diamond Beam Position Monitors with Radiofrequency Electronic Readout

    SciTech Connect

    Solar, B.; Graafsma, H.; Potdevin, G.; Trunk, U.; Morse, J.; Salome, M.

    2010-06-23

    Over the energy range 5{approx}30 keV a suitably contacted, thin ({approx}100 {mu}m) diamond plate can be operated in situ as a continuous monitor of X-ray beam intensity and position as the diamond absorbs only a small percentage of the incident beam. Single crystal diamond is a completely homogeneous material showing fast (ns), spatially uniform signal response and negligible (beams. We report on tests made at ESRF and DESY using diamond beam position monitors of simple quadrant electrode designs with metal contacts, operated using wideband electronic readout corresponding to the RF accelerator frequency. The instrumentation for these monitors must cover a large range of operating conditions: different beam sizes, fluxes, energies and time structure corresponding to the synchrotron fill patterns. Sophisticated new RF sampling electronics can satisfy most requirements: using a modified Libera Brilliance readout system, we measured the center of gravity position of a 25 {mu}m beam at the DORIS III F4 beam line at a rate of 130 Msample/s with narrowband filtering of a few MHz bandwidth. Digitally averaging the signal further provided a spatial resolution {approx}20 nm.

  17. Electron Beam Biasing of Substrates during Plasma Etching [1

    NASA Astrophysics Data System (ADS)

    Quick, A. K.; Hershkowitz, N.

    1997-10-01

    Electron beam biasing of substrates is being studied as an alternative to the usual method of using a capacitively coupled, rf-powered wafer chuck. The advantage of biasing with an electron beam is that the electrons which arrive at the wafer do so with an anisotropic velocity distribution similar to the plasma sheath-accelerated ions. This becomes important when etching large aspect ratio features. Isotropic plasma electrons can't follow the ions to the bottom of deep wells and they adhere to and charge up the feature sidewalls. This differential charging creates electric fields which deflect incoming ions and causes sidewall profile defects such as bowing, notching, and microtrenching and contributes to RIE(Reactive Ion Etch) lag( R. A. Gottscho, C. W. Jurgensen, and D. J. Vitkavage, J. Vac. Sci. Technol. B 10, Sep/Oct 1992, 2133.). The effects of etching sub-half micron nested poly-Silicon lines in Cl2 plasmas in the presence of an electron beam will be presented particularly in regard to notch suppression. The effects that the electron beam has on RIE lag suppression in SiO2 etching in fluorocarbon plasmas will also be discussed.

  18. Electron Beam Transport in Advanced Plasma Wave Accelerators

    SciTech Connect

    Williams, Ronald L

    2013-01-31

    The primary goal of this grant was to develop a diagnostic for relativistic plasma wave accelerators based on injecting a low energy electron beam (5-50keV) perpendicular to the plasma wave and observing the distortion of the electron beam's cross section due to the plasma wave's electrostatic fields. The amount of distortion would be proportional to the plasma wave amplitude, and is the basis for the diagnostic. The beat-wave scheme for producing plasma waves, using two CO2 laser beam, was modeled using a leap-frog integration scheme to solve the equations of motion. Single electron trajectories and corresponding phase space diagrams were generated in order to study and understand the details of the interaction dynamics. The electron beam was simulated by combining thousands of single electrons, whose initial positions and momenta were selected by random number generators. The model was extended by including the interactions of the electrons with the CO2 laser fields of the beat wave, superimposed with the plasma wave fields. The results of the model were used to guide the design and construction of a small laboratory experiment that may be used to test the diagnostic idea.

  19. Divergence of laser-driven relativistic electron beams.

    PubMed

    Debayle, A; Honrubia, J J; d'Humières, E; Tikhonchuk, V T

    2010-09-01

    Electron acceleration by ultrahigh intensity lasers is studied by means of two-dimensional planar particle-in-cell simulations. It is shown that the full divergence of the fast electron beam is defined by two complementary physical effects: the regular radial beam deviation depending on the electron radial position and the angular dispersion. If the scale length of the preplasma surrounding the solid target is sufficiently low, the radial deviation is determined by the transverse component of the laser ponderomotive force. The random angular dispersion is due to the small scale magnetic fields excited near the critical density due to the collisionless Weibel instability. When a preplasma is present, the radial beam deviation increases due to the electron acceleration in larger volumes and can become comparable to the local angular dispersion. This effect has been neglected so far in most of the fast electron transport calculations, overestimating significantly the beam collimation by resistive magnetic fields. Simulations with a two-dimensional cylindrically-symmetric hybrid code accounting for the electron radial velocity demonstrate a substantially reduced strength and a shorter penetration of the azimuthal magnetic field in solid targets.

  20. Beam breakup growth and reduction experiments in long-pulse electron beam transport

    NASA Astrophysics Data System (ADS)

    Menge, P. R.; Gilgenbach, R. M.; Lau, Y. Y.; Bosch, R. A.

    1994-02-01

    The results of an experimental program whose sole objective is to investigate the cumulative beam breakup instability (BBU) in electron beam accelerators are presented. The BBU growth rate scalings are examined with regard to beam current, focusing field, cavity Q, and propagation distance. A microwave cavity array was designed and fabricated to excite and measure the cumulative BBU resulting from beam interactions with the deflecting TM110 cavity mode. One phase of this experiment used high Q(≊1000) cavities with relatively large frequency spread (Δf/f0≊0.1%). The observed TM110 mode microwave growth between an upstream (second) and a downstream (tenth) cavity indicated BBU growth of 26 dB for an electron beam of kinetic energy of 750 keV, 45 A, and focused by a 1.1 kG solenoidal field. At beam currents of less than 100 A the experiments agreed well with a two-dimensional continuum theory; the agreement was worse at higher beam currents (≳100 A) due to beam loading. The second-phase experiments used lower Q(≊200) cavities with relatively low frequency spread (Δf/f0≊0.03%). Theory and experiment agreed well for beam currents up to 220 A. Distance scaling experiments were also performed by doubling the propagation length. Instability growth reduction experiments using the technique of external cavity coupling resulted in a factor of four decrease in energy in BBU growth when seven internal beam cavities were coupled by microwave cable to seven identical external dummy cavities. A theory invoking power sharing between the internal beam cavities and the external dummy cavities was used to explain the experimental reduction with excellent agreement using an equivalent circuit model.

  1. Ground Base Skylab Electron Beam Welds in Tantalum

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Comparison of ground-based (left) and Skylab (right) electron beam welds in pure tantalum (Ta) (10X magnification). Residual votices left behind in the ground-based sample after the electron beam passed were frozen into the grain structure. These occurred because of the rapid cooling rate at the high temperature. Although the thermal characteristics and electron beam travel speeds were comparable for the skylab sample, the residual vortices were erased in the grain structure. This may have been due to the fact that final grain size of the solidified material was smaller in the Skylab sample compared to the ground-based sample. The Skylab sample was processed in the M512 Materials Processing Facility (MPF) during Skylab SL-2 Mission. Principal Investigator was Richard Poorman.

  2. Ice-assisted electron beam lithography of graphene

    NASA Astrophysics Data System (ADS)

    Gardener, Jules A.; Golovchenko, J. A.

    2012-05-01

    We demonstrate that a low energy focused electron beam can locally pattern graphene coated with a thin ice layer. The irradiated ice plays a crucial role in the process by providing activated species that locally remove graphene from a silicon dioxide substrate. After patterning the graphene, the ice resist is easily removed by sublimation to leave behind a clean surface with no further processing. More generally, our findings demonstrate that ice-assisted e-beam lithography can be used to pattern very thin materials deposited on substrate surfaces. The procedure is performed in situ in a modified scanning electron microscope. Desirable structures such as nanoribbons are created using the method. Defects in graphene from electrons backscattered from the bulk substrate are identified. They extend several microns from the e-beam writing location. We demonstrate that these defects can be greatly reduced and localized by using thinner substrates and/or gentle thermal annealing.

  3. Modelling and simulation of beam formation in electron guns

    NASA Astrophysics Data System (ADS)

    Sabchevski, S.; Mladenov, G.; Titov, A.; Barbarich, I.

    1996-02-01

    This paper describes a new PC version of the software package GUN-EBT for computer simulation of beam formation in rotationally symmetric electron guns with thermionic cathodes. It is based on a self-consistent physical model which takes into account the beam space charge and the initial velocities effects. The theoretical framework used for both the formulation of the model and for the interpretation of the results of numerical experiments is the formalism of the charged particle dynamics in phase space. This enables not only a trajectory analysis (ray tracing) but also a phase-space analysis of beams to be performed. The package can be used as an effective tool for computer aided design and optimization of electron guns in various electron-optical systems. The operation of the package is illustrated with a typical example.

  4. Portable radiography system using a relativistic electron beam

    DOEpatents

    Hoeberling, Robert F.

    1990-01-01

    A portable radiographic generator is provided with an explosive magnetic flux compression generator producing the high voltage necessary to generate a relativistic electron beam. The relativistic electron beam is provided with target materials which generates the desired radiographic pulse. The magnetic flux compression generator may require at least two conventional explosively driven generators in series to obtain a desired output voltage of at least 1 MV. The cathode and anode configuration of the diode are selected to provide a switching action wherein a high impedance load is presented to the magnetic flux compression generator when the high voltage is being generated, and thereafter switching to a low impedance load to generate the relativistic electron beam. Magnetic flux compression generators can be explosively driven and provided in a relatively compact, portable form for use with the relativistic x-ray equipment.

  5. Portable radiography system using a relativistic electron beam

    DOEpatents

    Hoeberling, R.F.

    1987-09-22

    A portable radiographic generator is provided with an explosive magnetic flux compression generator producing the high voltage necessary to generate a relativistic electron beam. The relativistic electron beam is provided with target materials which generates the desired radiographic pulse. The magnetic flux compression generator may require at least two conventional explosively driven generators in series to obtain a desired output voltage of at least 1 MV. The cathode and anode configuration of the diode are selected to provide a switching action wherein a high impedance load is presented to the magnetic flux compression generator when the high voltage is being generated, and thereafter switching to a low impedance load to generate the relativistic electron beam. Magnetic flux compression generators can be explosively driven and provided in a relatively compact, portable form for use with the relativistic x-ray equipment. 8 figs.

  6. Strongly turbulent stabilization of electron beam-plasma interactions

    NASA Technical Reports Server (NTRS)

    Freund, H. P.; Haber, I.; Palmadesso, P.; Papadopoulos, K.

    1980-01-01

    The stabilization of electron beam interactions due to strongly turbulent nonlinearities is studied analytically and numerically for a wide range of plasma parameters. A fluid mode coupling code is described in which the effects of electron and ion Landau damping and linear growth due to the energetic electron beam are included in a phenomenological manner. Stabilization of the instability is found to occur when the amplitudes of the unstable modes exceed the threshold of the oscillating two-stream instability. The coordinate space structure of the turbulent spectrum which results clearly shows that soliton-like structures are formed by this process. Phenomenological models of both the initial stabilization and the asymptotic states are developed. Scaling laws between the beam-plasma growth rate and the fluctuations in the fields and plasma density are found in both cases, and shown to be in good agreement with the results of the simulation.

  7. Millimeter-wave generation with spiraling electron beams

    NASA Technical Reports Server (NTRS)

    Kulke, B.

    1971-01-01

    The feasibility of using the interaction between a thin, solid, spiraling electron beam of 10 to 20 kV energy and a microwave cavity to generate watts of CW millimeter-wave power was investigated. Experimental results are given for several prototype devices operating at 9.4 GHz and at 94 GHz. Power outputs of 5 W, and electronic efficiencies near 3%, were obtained at X band, and moderate gain was obtained at 94 GHz. The small-signal theory gives a good fit to the X-band data, and the device behavior at 94 GHz is as expected from the given beam characteristics. The performance is limited chiefly by the velocity spread in the spiraling electron beam, and once this can be brought under control, high-power generation of millimeter waves appears quite feasible with this type of device.

  8. Practical considerations for electron beam small field size dosimetry

    SciTech Connect

    Sharma, Subhash C.; Johnson, Martin W.; Gossman, Michael S. . E-mail: GossmanMS@erlanger.org

    2005-06-30

    Special care of superficial lesions surrounding critical structures, such as an eye, may require tight margins. When this is the case, small megavoltage electron treatment fields and nonstandard treatment distances become necessary. When the field size is found to be less than the practical range of the electron beam, dosimetric measurements should be performed. This research includes data proving that very small electron fields can be employed for treatment with appropriate beam flatness and penumbra. This is accomplished by first coning down the incident beam to a small field size, then secondly by adding a single lead sheet to the patient's skin surface. The aperture of the sheet is required to be greater than 2 x 2 cm{sup 2} in size, and must be cut properly to adequately confine the treatment area.

  9. Generation And Applications Of Electron-Beam Plasma Flows

    NASA Astrophysics Data System (ADS)

    Vasiliev, M. N.; Tun Win, Aung

    2015-03-01

    Plasma flows generated by continuous or interrupted injection of an electron beam into subsonic or supersonic gaseous streams are considered. Liquid and powder spraying by the electron-beam plasma (EBP) flows is studied as a technique of the aerosol plasma generation. A number of experimental setups generating both free plasma jets and plasma flows in channels are described. Examples of the EBP flows applications for industrial and aerospace technologies are given. The applications are shown to be based on unique properties of the EBP and its stability within very wide ranges of the plasma generation conditions. Some applications of the Hybrid Plasma (HP) generated by combined action of the electron beam (EB) and intermittent gas discharge on flows of gaseous mixtures and aerosols are presented as well.

  10. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    NASA Astrophysics Data System (ADS)

    Kaganovich, Igor; Sydorenko, Dmytro; Ventzek, Peter L. G.

    2016-09-01

    Electrons emitted from electrodes are accelerated by the sheath electric field and become the electron beams penetrating the plasma. The electron beam can interact with the plasma in collisionless manner via two-stream instability and produce suprathermal electrons. In order to understand the mechanism of suprathermal electrons acceleration, a beam-plasma system was simulated using a 1D3V particle-in-cell code EDIPIC. These simulation results show that the acceleration may be caused by the effects related to the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The short waves near the anode accelerate plasma bulk electrons to suprathermal energies. Rich complexity of beam-plasma interaction phenomena was also observed: intermittency and multiple regimes of two-stream instability in a dc discharge, band structure of the growth rate of the two-stream instability of an electron beam propagating in a bounded plasma, multi-stage acceleration of electrons in a finite system. This research was funded by US Department of Energy.

  11. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    NASA Astrophysics Data System (ADS)

    Sydorenko, Dmytro; Kaganovich, Igor D.; Ventzek, Peter L. G.

    2016-10-01

    Electrons emitted from electrodes are accelerated by the sheath electric field and become the electron beams penetrating the plasma. The electron beam can interact with the plasma in collisionless manner via two-stream instability and produce suprathermal electrons. In order to understand the mechanism of suprathermal electrons acceleration, a beam-plasma system was simulated using a 1D3V particle-in-cell code EDIPIC. These simulation results show that the acceleration may be caused by the effects related to the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The short waves near the anode accelerate plasma bulk electrons to suprathermal energies. Rich complexity of beam- plasma interaction phenomena was also observed: intermittency and multiple regimes of two-stream instability in a dc discharge, band structure of the growth rate of the two-stream instability of an electron beam propagating in a bounded plasma, multi-stage acceleration of electrons in a finite system.

  12. Generation of valley-polarized electron beam in bilayer graphene

    SciTech Connect

    Park, Changsoo

    2015-12-28

    We propose a method to produce valley-polarized electron beams using a bilayer graphene npn junction. By analyzing the transmission properties of electrons through the junction with zigzag interface in the presence of trigonal warping, we observe that there exist a range of incident energies and barrier heights in which transmitted electrons are well polarized and collimated. From this observation and by performing numerical simulations, it is demonstrated that valley-dependent electronic currents with nearly perfect polarization can be generated. We also show that the peak-to-peak separation angle between the polarized currents is tunable either by incident energy or by barrier height each of which is controlled by using top and back gate voltages. The results can be used for constructing an electron beam splitter to produce valley-polarized currents.

  13. Post-disruptive runaway electron beams in the COMPASS tokamak

    NASA Astrophysics Data System (ADS)

    Vlainic, Milos; Mlynar, J.; Cavalier, J.; Weinzettl, V.; Paprok, R.; Imrisek, M.; Ficker, O.; Varavin, M.; Vondracek, P.; Noterdaeme, J.-M.; Noterdaeme

    2015-10-01

    > For ITER-relevant runaway electron studies, such as suppression, mitigation, termination and/or control of a runaway beam, it is important to obtain the runaway electrons after the disruption. In this paper we report on the first discharges achieved with a post-disruptive runaway electron beam, termed a `runaway plateau', in the COMPASS tokamak. The runaway plateau is produced by a massive gas injection of argon. Almost all of the disruptions with runaway electron plateaus occurred during the plasma current ramp-up phase. The Ar injection discharges with and without a runaway plateau were compared for various parameters. Parametrisation of the discharges shows that the COMPASS disruptions fulfil the range of parameters important for runaway plateau occurrence. These parameters include electron density, electric field, disruption speed, effective safety factor, and the maximum current quench electric field. In addition to these typical parameters, the plasma current value just before the massive gas injection proved to be surprisingly important.

  14. Emittance measurements of the CLIO electron beam

    NASA Astrophysics Data System (ADS)

    Chaput, R.; Devanz, G.; Joly, P.; Kergosien, B.; Lesrel, J.

    1997-02-01

    We have designed a setup to measure the transverse emittance at the CLIO accelerator exit, based on the "3 gradients" method. The beam transverse size is measured simply by scanning it with a steering coil across a fixed jaw and recording the transmitted current, at various quadrupole strengths. A code then performs a complete calculation of the emittance using the transfer matrix of the quadrupole instead of the usual classical lens approximation. We have studied the influence of various parameters on the emittance: Magnetic field on the e-gun and the peak current. We have also improved a little the emittance by replacing a mismatched pipe between the buncher and accelerating section to avoid wake-field effects; The resulting improvements of the emittance have led to an increase in the FEL emitted power.

  15. CO2 remediation using high power electron beams

    NASA Astrophysics Data System (ADS)

    Petrova, Tzvetelina; Petrov, George; Apruzese, John; Wolford, Matthew

    2016-10-01

    To mitigate increasing CO2 concentrations in the atmosphere and alleviate global warming, we investigated a method of CO2 reduction using high-power electron beams. A series of experiments were conducted in which the reduction of CO2 is measured for different gas compositions and power deposition rates. Electron beam irradiation of gas containing 90% CO2 and 10% CH4 at beam energy density deposition of 4.2 J/cm3, reduced the CO2 concentration to 78%. Analogous experiments with a gas mixture containing 11.5% CO2, 11.5% CH4 and balance of Ar, reduced the CO2 concentration to below 11% with energy deposition 0.71 J/cm3. An electron beam deposition model computed the energy cost for breaking a CO2 molecule in flue gas (82% N2, 6% O2 and 12% CO2) to be 85 eV per molecule. Other techniques to enhance the removal of CO2 with pulsed electron beams are also explored, yielding new possible avenues of research.

  16. Magnetic Guiding of Electron Beam in Imploded Spherical Solid Targets

    NASA Astrophysics Data System (ADS)

    Johzaki, Tomoyuki; Sentoku, Yasuhiko; Nagatomo, Hideo; Sunahara, Atsushi; Sakagami, Hitoshi; Fujioka, Shinsuke; Shiraga, Hiroyuki; Endo, Takuma; Firex Team

    2015-11-01

    In fast ignition, the large divergence of electron beam is one of the most critical issues for efficient core heating. For improving the efficiency in FIREX project, we proposed the electron beam guiding by externally applied kT-class longitudinal magnetic fields. The 2D collisional PIC simulations showed that the electron beam can be successfully focused by the moderately-converging fields (mirror ratio RM < 20). On the other hand, in the implosion simulation for a cone-attached CD shell target with B-field, the mirror ratio reaches RM > 100 at the maximum compression, which is too high for efficient guiding. Recently, we introduced a spherical solid target, where the mirror ratio is moderate since the density compressibility stays low (~30) and the magnetic-field compressibility will also be low. In the conference, we will show the integrated simulation results for core heating by fast electron beam with large beam divergence under the compressed core and magnetic fields formed through implosion of a solid spherical target. This work is supported by NIFS Collaboration Research program (NIFS12KUGK057, NIFS15KUGK094), JSPS KAKENHI (25400534, 25400539, 26400532) and DOE/OFES under DE-SC0008827.

  17. Three-axis electron-beam test facility

    NASA Technical Reports Server (NTRS)

    Dayton, J. A., Jr.; Ebihara, B. T.

    1981-01-01

    An electron beam test facility, which consists of a precision multidimensional manipulator built into an ultra-high-vacuum bell jar, was designed, fabricated, and operated at Lewis Research Center. The position within the bell jar of a Faraday cup which samples current in the electron beam under test, is controlled by the manipulator. Three orthogonal axes of motion are controlled by stepping motors driven by digital indexers, and the positions are displayed on electronic totalizers. In the transverse directions, the limits of travel are approximately + or - 2.5 cm from the center with a precision of 2.54 micron (0.0001 in.); in the axial direction, approximately 15.0 cm of travel are permitted with an accuracy of 12.7 micron (0.0005 in.). In addition, two manually operated motions are provided, the pitch and yaw of the Faraday cup with respect to the electron beam can be adjusted to within a few degrees. The current is sensed by pulse transformers and the data are processed by a dual channel box car averager with a digital output. The beam tester can be operated manually or it can be programmed for automated operation. In the automated mode, the beam tester is controlled by a microcomputer (installed at the test site) which communicates with a minicomputer at the central computing facility. The data are recorded and later processed by computer to obtain the desired graphical presentations.

  18. A new beam source for free electron lasers

    SciTech Connect

    Wang, M.C.; Wang, Z.J.; Zhu, J.B.

    1995-12-31

    A high power, high current density and high voltage electron beam was generated with the pseudospark discharge (PS), this is a new beam source for free electron lasers. The design and construction of the pseudospark discharge was described, the device has low cost and is easy to fabricate. The experiments are presented, the configuration parameters of the modified pulse line accelerator (PLA) are as follows. The PS hollow cavity has a 3 cm diameter and 4.1 cm long. The discharge chamber consists of planar cathode with hollow cavity, sets of intermediate electrodes and insulators with a common channel, and a planar anode. The electrodes are made of brass and the insulators are made of Plexiglas. The diameter of the channel is 3.2 mm. The anode-cathode gap distance is varied in 10-100 mm. The electron beams have voltage of 200 KeV, current of 2 KA and beam diameter of 1mm. The beam penetrated a 0.3 mm hole on a copper foil of 0.05 mm thick at the distance of 5 cm from the anode and penetrated a 0.6 mm hole on an acid-sensitive film at the distance of 15 cm. A compact free electron laser with a table size is discussed.

  19. Investigation of electron beam transport in a helical undulator

    SciTech Connect

    Jeong, Y.U.; Lee, B.C.; Kim, S.K.

    1995-12-31

    Lossless transport of electrons through the undulator is essential for CW operation of the FELs driven by recirculating electrostatic accelerators. We calculate the transport ratio of an electron beam in a helical undulator by using a 3-D simulation code and compare the results with the experimental results. The energy and the current of the electron beam are 400 keV and 2 A, respectively. The 3-D distribution of the magnetic field of a practical permanent-magnet helical undulator is measured and is used in the calculations. The major parameters of the undutlator are : period = 32 mm, number of periods = 20, number of periods in adiabatic region = 3.5, magnetic field strength = 1.3 kG. The transport ratio is very sensitive to the injection condition of the electron beam such as the emittance, the diameter, the divergence, etc.. The injection motion is varied in the experiments by changing the e-gun voltage or the field strength of the focusing magnet located at the entrance of the undulator. It is confirmed experimentally and with simulations that most of the beam loss occurs at the adiabatic region of the undulator regardless of the length of the adiabatic region The effect of axial guiding magnetic field on the beam finish is investigated. According to the simulations, the increase of the strength of axial magnetic field from 0 to 1 kG results in the increase of the transport ratio from 15 % to 95%.

  20. Drag of ballistic electrons by an ion beam

    SciTech Connect

    Gurevich, V. L.; Muradov, M. I.

    2015-12-15

    Drag of electrons of a one-dimensional ballistic nanowire by a nearby one-dimensional beam of ions is considered. We assume that the ion beam is represented by an ensemble of heavy ions of the same velocity V. The ratio of the drag current to the primary current carried by the ion beam is calculated. The drag current turns out to be a nonmonotonic function of velocity V. It has a sharp maximum for V near v{sub nF}/2, where n is the number of the uppermost electron miniband (channel) taking part in conduction and v{sub nF} is the corresponding Fermi velocity. This means that the phenomenon of ion beam drag can be used for investigation of the electron spectra of ballistic nanostructures. We note that whereas observation of the Coulomb drag between two parallel quantum wires may in general be complicated by phenomena such as tunneling and phonon drag, the Coulomb drag of electrons of a one-dimensional ballistic nanowire by an ion beam is free of such spurious effects.

  1. Electron-Beam Diagnostic Methods for Hypersonic Flow Diagnostics

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The purpose of this work was the evaluation of the use of electron-bean fluorescence for flow measurements during hypersonic flight. Both analytical and numerical models were developed in this investigation to evaluate quantitatively flow field imaging concepts based upon the electron beam fluorescence technique for use in flight research and wind tunnel applications. Specific models were developed for: (1) fluorescence excitation/emission for nitrogen, (2) rotational fluorescence spectrum for nitrogen, (3) single and multiple scattering of electrons in a variable density medium, (4) spatial and spectral distribution of fluorescence, (5) measurement of rotational temperature and density, (6) optical filter design for fluorescence imaging, and (7) temperature accuracy and signal acquisition time requirements. Application of these models to a typical hypersonic wind tunnel flow is presented. In particular, the capability of simulating the fluorescence resulting from electron impact ionization in a variable density nitrogen or air flow provides the capability to evaluate the design of imaging instruments for flow field mapping. The result of this analysis is a recommendation that quantitative measurements of hypersonic flow fields using electron-bean fluorescence is a tractable method with electron beam energies of 100 keV. With lower electron energies, electron scattering increases with significant beam divergence which makes quantitative imaging difficult. The potential application of the analytical and numerical models developed in this work is in the design of a flow field imaging instrument for use in hypersonic wind tunnels or onboard a flight research vehicle.

  2. A tunable electronic beam splitter realized with crossed graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Brandimarte, Pedro; Engelund, Mads; Papior, Nick; Garcia-Lekue, Aran; Frederiksen, Thomas; Sánchez-Portal, Daniel

    2017-03-01

    Graphene nanoribbons (GNRs) are promising components in future nanoelectronics due to the large mobility of graphene electrons and their tunable electronic band gap in combination with recent experimental developments of on-surface chemistry strategies for their growth. Here, we explore a prototype 4-terminal semiconducting device formed by two crossed armchair GNRs (AGNRs) using state-of-the-art first-principles transport methods. We analyze in detail the roles of intersection angle, stacking order, inter-GNR separation, GNR width, and finite voltages on the transport characteristics. Interestingly, when the AGNRs intersect at θ =60° , electrons injected from one terminal can be split into two outgoing waves with a tunable ratio around 50% and with almost negligible back-reflection. The split electron wave is found to propagate partly straight across the intersection region in one ribbon and partly in one direction of the other ribbon, i.e., in analogy with an optical beam splitter. Our simulations further identify realistic conditions for which this semiconducting device can act as a mechanically controllable electronic beam splitter with possible applications in carbon-based quantum electronic circuits and electron optics. We rationalize our findings with a simple model suggesting that electronic beam splitters can generally be realized with crossed GNRs.

  3. Electron beam recrystallization of amorphous semiconductor materials

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.

    1968-01-01

    Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

  4. Parametric Modeling of Electron Beam Loss in Synchrotron Light Sources

    SciTech Connect

    Sayyar-Rodsari, B.; Schweiger, C.; Hartman, E.; Corbett, J.; Lee, M.; Lui, P.; Paterson, E.; /SLAC

    2007-11-28

    Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstrahlung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.

  5. Spontaneous Formation of Closed-Field Torus Equilibrium via Current Jump Observed in an Electron-Cyclotron-Heated Plasma

    SciTech Connect

    Yoshinaga, T.; Uchida, M.; Tanaka, H.; Maekawa, T.

    2006-03-31

    Spontaneous current jump resulting in the formation of closed field equilibrium has been observed in electron-cyclotron-heated toroidal plasmas under steady external fields composed of a toroidal field and a relatively weak vertical field in the low aspect ratio torus experiment device. This bridges the gap between the open field equilibrium maintained by a pressure-driven current in the external field and the closed field equilibrium at a larger current. Experimental results and theoretical analyses suggest a current jump model that is based on the asymmetric electron confinement along the field line appearing upon simultaneous transitions of field topology and equilibrium.

  6. Transient fields produced by a cylindrical electron beam flowing through a plasma

    NASA Astrophysics Data System (ADS)

    Firpo, Marie-Christine

    2012-10-01

    Fast ignition schemes (FIS) for inertial confinement fusion should involve in their final stage the interaction of an ignition beam composed of MeV electrons laser generated at the critical density surface with a dense plasma target. In this study, the out-of-equilibrium situation in which an initially sharp-edged cylindrical electron beam, that could e.g. model electrons flowing within a wire [1], is injected into a plasma is considered. A detailed computation of the subsequently produced magnetic field is presented [2]. The control parameter of the problem is shown to be the ratio of the beam radius to the electron skin depth. Two alternative ways to address analytically the problem are considered: one uses the usual Laplace transform approach, the other one involves Riemann's method in which causality conditions manifest through some integrals of triple products of Bessel functions.[4pt] [1] J.S. Green et al., Surface heating of wire plasmas using laser-irradiated cone geometries, Nature Physics 3, 853--856 (2007).[0pt] [2] M.-C. Firpo, http://hal.archives-ouvertes.fr/hal-00695629, to be published (2012).

  7. Numerical Simulation of Beam-Beam Effects in the Proposed Electron-Ion Colider at Jefferson Lab

    SciTech Connect

    Balsa Terzic, Yuhong Zhang

    2010-05-01

    One key limiting factor to a collider luminosity is beam-beam interactions which usually can cause serious emittance growth of colliding beams and fast reduction of luminosity. Such nonlinear collective beam effect can be a very serious design challenge when the machine parameters are pushed into a new regime. In this paper, we present simulation studies of the beam-beam effect for a medium energy ring-ring electron-ion collider based on CEBAF.

  8. WE-A-207-02: Electron Beam Therapy - Current Status and Future Directions

    SciTech Connect

    Wu, Q.

    2015-06-15

    In memory of the significant contribution of Dr. Jacques Ovadia to electron beam techniques, this session will review recent, advanced techniques which are reinvigorating the science of electron beam radiation therapy. Recent research efforts in improving both the applicability and quality of the electron beam therapy will be discussed, including modulated electron beam radiotherapy (MERT) and dynamic electron arc radiotherapy (DEAR). Learning Objectives: To learn about recent advances in electron beam therapy, including modulated electron beam therapy and dynamic electron arc therapy (DEAR). Put recent advances in the context of work that Dr. Ovadia pursued during his career in medical physics.

  9. Numerical modeling of electron-beam welding of dissimilar metals

    NASA Astrophysics Data System (ADS)

    Krektuleva, R. A.; Cherepanov, O. I.; Cherepanov, R. O.

    2016-11-01

    This paper is devoted to numerical modeling of heat transfer processes and estimation of thermal stresses in weld seams created by electron beam welding of heterogeneous metals. The mathematical model is based on a system of equations that includes the Lagrange's variational equation of theory of plasticity and variational equation of M. Biot's principle to simulate the heat transfer processes. The two-dimensional problems (plane strain and plane stress) are considered for estimation of thermal stresses in welds considering differences of mechanical properties of welded materials. The model is developed for simulation of temperature fields and stresses during electron beam welding.

  10. High-Power Microwave Switch Employing Electron Beam Triggering

    SciTech Connect

    Hirshfield, Jay L

    2012-09-19

    A high-power active microwave pulse compressor is described that modulates the quality factor Q of the energy storage cavity by a new means involving mode conversion controlled by a triggered electron-beam discharge through a switch cavity. The electron beam is emitted from a diamond-coated molybdenum cathode. This report describes the principle of operation, the design of the switch, the configuration used for the test, and the experimental results. The pulse compressor produced output pulses with 140 - 165 MW peak power, power gain of 16 - 20, and pulse duration of 16 - 20 ns at a frequency of 11.43 GHz.

  11. Biodegradability enhancement of textile wastewater by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Tak-Hyun; Lee, Jae-Kwang; Lee, Myun-Joo

    2007-06-01

    Textile wastewater generally contains various pollutants, which can cause problems during biological treatment. Electron beam radiation technology was applied to enhance the biodegradability of textile wastewater for an activated sludge process. The biodegradability (BOD 5/COD) increased at a 1.0 kGy dose. The biorefractory organic compounds were converted into more easily biodegradable compounds such as organic acids having lower molecular weights. In spite of the short hydraulic retention time (HRT) of the activated sludge process, not only high organic removal efficiencies, but also high microbial activities were achieved. In conclusion, textile wastewater was effectively treated by the combined process of electron beam radiation and an activated sludge process.

  12. Pulsed-electron-beam annealing of ion-implantation damage

    NASA Technical Reports Server (NTRS)

    Greenwald, A. C.; Kirkpatrick, A. R.; Little, R. G.; Minnucci, J. A.

    1979-01-01

    Short-duration high-intensity pulsed electron beams have been used to anneal ion-implantation damage in silicon and to electrically activate the dopant species. Lattice regrowth and dopant activation were determined using He(+)-4 backscattering, SEM, TEM, and device performance characteristics as diagnostic techniques. The annealing mechanism is believed to be liquid-phase epitaxial regrowth initiating from the substrate. The high-temperature transient pulse produced by the electron beam causes the dopant to diffuse rapidly in the region where the liquid state is achieved.

  13. Evaporation rate and composition monitoring of electron beam PVD processes

    SciTech Connect

    Anklam, T.M.; Berzins, L.V.; Braun, D.G.; Haynam, C.; Meier, T.; McClelland, M.A.

    1995-03-01

    Lawrence Livermore National Laboratory (LLNL) is developing sensor and control technology to improve the quality and range of applicability of electron beam PVD. The approach being developed uses tunable lasers to measure, the density and composition of the vapor plume. This paper reviews the principles of operation of laser based sensors and discusses data from experiments in which titanium and niobium are co-vaporized. Laser data agreed well with deposited film compositions and spatial variations in deposited film cross sections. Laser based vapor monitoring appears to have broad applicability and has the potential to extend the use of high rate electron beam PVD.

  14. Radial electron-beam-breakup transit-time oscillator

    DOEpatents

    Kwan, Thomas J. T.; Mostrom, Michael A.

    1998-01-01

    A radial electron-beam-breakup transit-time oscillator (RBTO) provides a compact high power microwave generator. The RBTO includes a coaxial vacuum transmission line having an outer conductor and an inner conductor. The inner conductor defines an annular cavity with dimensions effective to support an electromagnetic field in a TEM.sub.00m mode. A radial field emission cathode is formed on the outer conductor for providing an electron beam directed toward the annular cavity electrode. Microwave energy is then extracted from the annular cavity electrode.

  15. Radio Spectroscopic Imaging of Electron Beams in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Bastian, Timothy S.; Chen, B.

    2012-05-01

    The recently upgraded Jansky Very Large Array was used to observe the radio emission from a C class solar flare. Observations were performed from 1-2 GHz with a spectral resolution of 1 MHz and time resolution of 100 ms. A number of fast-drift, type-III-like radio bursts was observed, the result of nonthermal electron beams propagating from the flare site, guided by the coronal magnetic field. Using these dynamic, imaging, spectroscopic observations, the electron beam trajectories are deduced.Implications are briefly discussed.

  16. Generation of subnanosecond electron beams in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kostyrya, I. D.; Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Rybka, D. V.

    2009-11-01

    Optimum conditions for the generation of runaway electron beams with maximum current amplitudes and densities in nanosecond pulsed discharges in air at atmospheric pressure are determined. A supershort avalanche electron beam (SAEB) with a current amplitude of ˜30 A, a current density of ˜20 A/cm2, and a pulse full width at half maximum (FWHM) of ˜100 ps has been observed behind the output foil of an air-filled diode. It is shown that the position of the SAEB current maximum relative to the voltage pulse front exhibits a time shift that varies when the small-size collector is moved over the foil surface.

  17. Electron beam collector for a microwave power tube

    DOEpatents

    Dandl, Raphael A.

    1980-01-01

    This invention relates to a cylindrical, electron beam collector that efficiently couples the microwave energy out of a high power microwave source while stopping the attendant electron beam. The interior end walls of the collector are a pair of facing parabolic mirrors and the microwave energy from an input horn is radiated between the two mirrors and reassembled at the entrance to the output waveguide where the transmitted mode is reconstructed. The mode transmission through the collector of the present invention has an efficiency of at least 94%.

  18. Ultra-bright pulsed electron beam with low longitudinal emittance

    DOEpatents

    Zolotorev, Max

    2010-07-13

    A high-brightness pulsed electron source, which has the potential for many useful applications in electron microscopy, inverse photo-emission, low energy electron scattering experiments, and electron holography has been described. The source makes use of Cs atoms in an atomic beam. The source is cycled beginning with a laser pulse that excites a single Cs atom on average to a band of high-lying Rydberg nP states. The resulting valence electron Rydberg wave packet evolves in a nearly classical Kepler orbit. When the electron reaches apogee, an electric field pulse is applied that ionizes the atom and accelerates the electron away from its parent ion. The collection of electron wave packets thus generated in a series of cycles can occupy a phase volume near the quantum limit and it can possess very high brightness. Each wave packet can exhibit a considerable degree of coherence.

  19. Ultrafast electron diffraction from non-equilibrium phonons in femtosecond laser heated Au films

    SciTech Connect

    Chase, T.; Trigo, M.; Reid, A. H.; Li, R.; Vecchione, T.; Shen, X.; Weathersby, S.; Coffee, R.; Hartmann, N.; Reis, D. A.; Wang, X. J.; Dürr, H. A.

    2016-01-25

    We use ultrafast electron diffraction to detect the temporal evolution of non-equilibrium phonons in femtosecond laser-excited ultrathin single-crystalline gold films. From the time-dependence of the Debye-Waller factor, we extract a 4.7 ps time-constant for the increase in mean-square atomic displacements. The observed increase in the diffuse scattering intensity demonstrates that the energy transfer from laser-heated electrons to phonon modes near the X and K points in the Au fcc Brillouin zone proceeds with timescales of 2.3 and 2.9 ps, respectively, faster than the Debye-Waller average mean-square displacement.

  20. Electron Broadening of Isolated Lines with Stationary Non-Equilibrium Level Populations

    SciTech Connect

    Iglesias, C A

    2005-01-12

    It is shown that a quantum kinetic theory approach to line broadening, extended to stationary non-equilibrium states, yields corrections to the standard electron impact widths of isolated lines that depend on the population of the radiator internal levels. A consistent classical limit from a general quantum treatment of the perturbing electrons also introduces corrections to the isolated line widths. Both effects are essential in preserving detailed-balance relations. Preliminary analysis indicates that these corrections may resolve existing discrepancies between theoretical and experimental widths of isolated lines. An experimental test of the results is proposed.

  1. Electron-beam-induced ferroelectric domain behavior in the transmission electron microscope: Toward deterministic domain patterning

    NASA Astrophysics Data System (ADS)

    Hart, James L.; Liu, Shi; Lang, Andrew C.; Hubert, Alexander; Zukauskas, Andrius; Canalias, Carlota; Beanland, Richard; Rappe, Andrew M.; Arredondo, Miryam; Taheri, Mitra L.

    2016-11-01

    We report on transmission electron microscope beam-induced ferroelectric domain nucleation and motion. While previous observations of this phenomenon have been reported, a consistent theory explaining induced domain response is lacking, and little control over domain behavior has been demonstrated. We identify positive sample charging, a result of Auger and secondary electron emission, as the underlying mechanism driving domain behavior. By converging the electron beam to a focused probe, we demonstrate controlled nucleation of nanoscale domains. Molecular dynamics simulations performed are consistent with experimental results, confirming positive sample charging and reproducing the result of controlled domain nucleation. Furthermore, we discuss the effects of sample geometry and electron irradiation conditions on induced domain response. These findings elucidate past reports of electron beam-induced domain behavior in the transmission electron microscope and provide a path towards more predictive, deterministic domain patterning through electron irradiation.

  2. Transport coefficients and heat fluxes in non-equilibrium high-temperature flows with electronic excitation

    NASA Astrophysics Data System (ADS)

    Istomin, V. A.; Kustova, E. V.

    2017-02-01

    The influence of electronic excitation on transport processes in non-equilibrium high-temperature ionized mixture flows is studied. Two five-component mixtures, N 2 / N2 + / N / N + / e - and O 2 / O2 + / O / O + / e - , are considered taking into account the electronic degrees of freedom for atomic species as well as the rotational-vibrational-electronic degrees of freedom for molecular species, both neutral and ionized. Using the modified Chapman-Enskog method, the transport coefficients (thermal conductivity, shear viscosity and bulk viscosity, diffusion and thermal diffusion) are calculated in the temperature range 500-50 000 K. Thermal conductivity and bulk viscosity coefficients are strongly affected by electronic states, especially for neutral atomic species. Shear viscosity, diffusion, and thermal diffusion coefficients are not sensible to electronic excitation if the size of excited states is assumed to be constant. The limits of applicability for the Stokes relation are discussed; at high temperatures, this relation is violated not only for molecular species but also for electronically excited atomic gases. Two test cases of strongly non-equilibrium flows behind plane shock waves corresponding to the spacecraft re-entry (Hermes and Fire II) are simulated numerically. Fluid-dynamic variables and heat fluxes are evaluated in gases with electronic excitation. In inviscid flows without chemical-radiative coupling, the flow-field is weakly affected by electronic states; however, in viscous flows, their influence can be more important, in particular, on the convective heat flux. The contribution of different dissipative processes to the heat transfer is evaluated as well as the effect of reaction rate coefficients. The competition of diffusion and heat conduction processes reduces the overall effect of electronic excitation on the convective heating, especially for the Fire II test case. It is shown that reliable models of chemical reaction rates are of great

  3. Exposure simulation of electron beam microcolumn lithography

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Kon; Oh, Hye-Keun

    2004-05-01

    We propose an improved method to describe the electron-resist interaction based on Dill"s model for exposure simulation. For this purpose, Monte Carlo simulation was performed to obtain the energy intensity distribution in the chemically amplified resist. Tabulated Mott data for elastic scattering, Moller and Vriens cross sections for inelastic scattering, and Modified Bethe equation plus discrete energy loss for energy loss are used for the calculation of the energy intensity distribution. Through the electron-resist interaction, the energy intensity distribution changes resist components into the exposure production such as the photoacid concentration or the photoacid generator inside resists with various pattern shapes by using the modified Dill"s model. Our simulation profiles show a good agreement with experimental profiles.

  4. Nonlinear transmission line based electron beam driver

    SciTech Connect

    French, David M.; Hoff, Brad W.; Tang Wilkin; Heidger, Susan; Shiffler, Don; Allen-Flowers, Jordan

    2012-12-15

    Gated field emission cathodes can provide short electron pulses without the requirement of laser systems or cathode heating required by photoemission or thermionic cathodes. The large electric field requirement for field emission to take place can be achieved by using a high aspect ratio cathode with a large field enhancement factor which reduces the voltage requirement for emission. In this paper, a cathode gate driver based on the output pulse train from a nonlinear transmission line is experimentally demonstrated. The application of the pulse train to a tufted carbon fiber field emission cathode generates short electron pulses. The pulses are approximately 2 ns in duration with emission currents of several mA, and the train contains up to 6 pulses at a frequency of 100 MHz. Particle-in-cell simulation is used to predict the characteristic of the current pulse train generated from a single carbon fiber field emission cathode using the same technique.

  5. Electron-Beam Controlled Semiconductor Switches

    DTIC Science & Technology

    1993-11-02

    34 Proceedings of the 7th IEEE Pulsed Power Conference (1989) 348- 351. Thomas, B, et al., "Investigation of Surface Flashover in Silicon...Phbs- trolled semiconductor switch. In 1990 he joined the Naval Surface Warfare ical Electronics Research Institute His current research interests...field of 17 depletion region over the entire zone I1. In addition to this kV/cm. At this point, problems with surface flashover prevented depletion

  6. Microwave Emission from Relativistic Electron Beams.

    DTIC Science & Technology

    1983-12-23

    serious problems . The rippled-field magnetron is a novel source of coherent radiation devoid " of physical slow-wave structures and capable RrM t r i...initial experiments on a circular FEL which uses a monoenergetic rotating electron ring and thereby circumvents the problem of velocity shear... problem how best to couple out the avail- able radiation. Our horn antenna merely probes the radiation field and re- ceives only a small fraction of

  7. Precision Electron Beam Polarimetry in Hall C at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Gaskell, David

    2013-10-01

    The electron beam polarization in experimental Hall C at Jefferson Lab is measured using two devices. The Hall-C/Basel Møller polarimeter measures the beam polarization via electron-electron scattering and utilizes a novel target system in which a pure iron foil is driven to magnetic saturation (out of plane) using a superconducting solenoid. A Compton polarimeter measures the polarization via electron-photon scattering, where the photons are provided by a high-power, CW laser coupled to a low gain Fabry-Perot cavity. In this case, both the Compton-scattered electrons and backscattered photons provide measurements of the beam polarization. Results from both polarimeters, acquired during the Q-Weak experiment in Hall C, will be presented. In particular, the results of a test in which the Møller and Compton polarimeters made interleaving measurements at identical beam currents will be shown. In addition, plans for operation of both devices after completion of the Jefferson Lab 12 GeV Upgrade will also be discussed.

  8. Suppression of shot noise and spontaneous radiation in electron beams

    SciTech Connect

    Litvinenko,V.

    2009-08-23

    Shot noise in the electron beam distribution is the main source of noise in high-gain FEL amplifiers, which may affect applications ranging from single- and multi-stage HGHG FELs to an FEL amplifier for coherent electron cooling. This noise also imposes a fundamental limit of about 10{sup 6} on FEL gain, after which SASE FELs saturate. There are several advantages in strongly suppressing this shot noise in the electron beam, and the corresponding spontaneous radiation. For more than a half-century, a traditional passive method has been used successfully in practical low-energy microwave electronic devices to suppress shot noise. Recently, it was proposed for this purpose in FELs. However, being passive, the method has some significant limitations and is hardly suitable for the highly inhomogeneous beams of modern high-gain FELs. I present a novel active method of suppressing, by many orders-of-magnitude, the shot noise in relativistic electron beams. I give a theoretical description of the process, and detail its fundamental limitation.

  9. Electron beam irradiation of gemstone for color enhancement

    SciTech Connect

    Idris, Sarada; Ghazali, Zulkafli; Hashim, Siti A'iasah; Ahmad, Shamshad; Jusoh, Mohd Suhaimi

    2012-09-26

    Numerous treatment of gemstones has been going on for hundreds of years for enhancing color and clarity of gems devoid of these attributes. Whereas previous practices included fraudulent or otherwise processes to achieve the color enhancement, the ionizing radiation has proven to be a reliable and reproducible technique. Three types of irradiation processes include exposure to gamma radiation, electron beam irradiation and the nuclear power plants. Electron Beam Irradiation of Gemstone is a technique in which a gemstone is exposed to highly ionizing radiation electron beam to knock off electrons to generate color centers culminating in introduction of deeper colors. The color centers may be stable or unstable. Below 9MeV, normally no radioactivity is introduced in the exposed gems. A study was conducted at Electron Beam Irradiation Centre (Alurtron) for gemstone color enhancement by using different kind of precious gemstones obtained from Pakistan. The study shows that EB irradiation not only enhances the color but can also improves the clarity of some type of gemstones. The treated stones included kunzite, tourmaline, topaz, quartz, aquamarine and cultured pearls. Doses ranging from 25 kGy to 200 KGy were employed to assess the influence of doses on color and clarity and to select the optimum doses. The samples used included both the natural and the faceted gemstones. It is concluded that significant revenue generation is associated with the enhancement of the color in clarity of gemstones which are available at very cheap price in the world market.

  10. Electron beam irradiation of gemstone for color enhancement

    NASA Astrophysics Data System (ADS)

    Idris, Sarada; Ghazali, Zulkafli; Hashim, Siti A'iasah; Ahmad, Shamshad; Jusoh, Mohd Suhaimi

    2012-09-01

    Numerous treatment of gemstones has been going on for hundreds of years for enhancing color and clarity of gems devoid of these attributes. Whereas previous practices included fraudulent or otherwise processes to achieve the color enhancement, the ionizing radiation has proven to be a reliable and reproducible technique. Three types of irradiation processes include exposure to gamma radiation, electron beam irradiation and the nuclear power plants. Electron Beam Irradiation of Gemstone is a technique in which a gemstone is exposed to highly ionizing radiation electron beam to knock off electrons to generate color centers culminating in introduction of deeper colors. The color centers may be stable or unstable. Below 9MeV, normally no radioactivity is introduced in the exposed gems. A study was conducted at Electron Beam Irradiation Centre (Alurtron) for gemstone color enhancement by using different kind of precious gemstones obtained from Pakistan. The study shows that EB irradiation not only enhances the color but can also improves the clarity of some type of gemstones. The treated stones included kunzite, tourmaline, topaz, quartz, aquamarine and cultured pearls. Doses ranging from 25 kGy to 200 KGy were employed to assess the influence of doses on color and clarity and to select the optimum doses. The samples used included both the natural and the faceted gemstones. It is concluded that significant revenue generation is associated with the enhancement of the color in clarity of gemstones which are available at very cheap price in the world market.

  11. Slit disk for modified faraday cup diagnostic for determining power density of electron and ion beams

    DOEpatents

    Teruya, Alan T [Livermore, CA; Elmer,; John, W [Danville, CA; Palmer, Todd A [State College, PA

    2011-03-08

    A diagnostic system for characterization of an electron beam or an ion beam includes an electrical conducting disk of refractory material having a circumference, a center, and a Faraday cup assembly positioned to receive the electron beam or ion beam. At least one slit in the disk provides diagnostic characterization of the electron beam or ion beam. The at least one slit is located between the circumference and the center of the disk and includes a radial portion that is in radial alignment with the center and a portion that deviates from radial alignment with the center. The electron beam or ion beam is directed onto the disk and translated to the at least one slit wherein the electron beam or ion beam enters the at least one slit for providing diagnostic characterization of the electron beam or ion beam.

  12. Simulation of radial expansion of an electron beam injected into a background plasma

    NASA Technical Reports Server (NTRS)

    Koga, J.; Lin, C. S.

    1989-01-01

    A 2-D electrostatic particle code was used to study the beam radial expansion of a nonrelativistic electron beam injected from an isolated equipotential conductor into a background plasma. The simulations indicate that the beam radius is generally proportional to the beam electron gyroradius when the conductor is charged to a large potential. The simulations also suggest that the charge buildup at the beam stagnation point causes the beam radial expansion. From a survey of the simulation results, it is found that the ratio of the beam radius to the beam electron gyroradius increases with the square root of beam density and decreases inversely with beam injection velocity. This dependence is explained in terms of the ratio of the beam electron Debye length to the ambient electron Debye length. These results are most applicable to the SEPAC electron beam injection experiments from Spacelab 1, where high charging potential was observed.

  13. Beam loading compensation for acceleration of multi-bunch electron beam train

    NASA Astrophysics Data System (ADS)

    Liu, Shengguang; Fukuda, Masafumi; Araki, Sakae; Terunuma, Nobuhiro; Urakawa, Junji; Hirano, Koichiro; Sasao, Noboru

    2008-01-01

    The laser undulator compact X-ray source (LUCX) is a test bench used with the compact, high-brightness X-ray generator at KEK (High Energy Accelerator Research Organization). Our group is conducting experiments with LUCX to demonstrate the possibility of K-edge digital subtraction angiography, based on Compton scattering. One of the challenging problems is to generate high-brightness multi-bunch electron beams to compensate for the energy difference arising from the beam loading effect. In this paper we calculate the transient beam loading voltage and energy gain from the RF field in the gun and accelerating tube for a multi-bunch train. To do so we consider the process by which the RF field builds up in the gun and accelerating tube, and the special shape of the RF pulse. We generate and accelerate 100 bunches with a 50 nC electron bunch train, effectively compensating for the beam loading effect by adjusting the injection timing. Using a beam position monitor (BPM) and optical transition radiation (OTR) system, we measure the electron beam energy bunch by bunch. The average energy of a 100-bunch train is 40.5 MeV and the maximum energy difference from bunch to bunch is 0.26 MeV.

  14. Evaluating the diffusive equilibrium models: Comparison with the IMAGE RPI field-aligned electron density measurements

    NASA Astrophysics Data System (ADS)

    Ozhogin, P.; Song, P.; Tu, J.; Reinisch, B. W.

    2014-06-01

    The diffusive equilibrium models that are widely used by the space physics community to describe the plasma densities in the plasmasphere are evaluated with field-aligned electron density measurements from the radio plasma imager (RPI) instrument onboard the IMAGE satellite. The original mathematical form of the diffusive equilibrium model was based on the hydrostatic equilibrium along the magnetic field line with the centrifugal force and the field-aligned electrostatic force as well as a large number of simplifying approximations. Six free parameters in the mathematical form have been conventionally determined from observations. We evaluate four sets of the parameters that have been reported in the literature. The evaluation is made according to the equatorial radial distance dependence, latitudinal dependence at a given radial distance, and the combined radial and latitudinal dependences. We find that the mathematical form given in the diffusive equilibrium model is intrinsically incompatible with the measurements unless another large number of free parameters are artificially introduced, which essentially changes the nature of a theoretical model to an empirical model.

  15. Electron beam induced THz emissions from nanotube array

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Kumar, Pawan

    2016-10-01

    A new scheme of terahertz radiation generation by passing an ultrashort electron bunch over a planar array of nanotube/nanorod across their lengths is proposed and analyzed. The beam pulse exerts a repulsive impulse on the free electron cylinder of each nanorod and displaces them with respect to ion cylinder. After the passage of the pulse, the electron cylinders oscillate at their natural frequency ω p / √{ 2 } (where ω p is the plasma frequency of electrons in each carbon nanotube) acting as phased array dipole antennae, emitting THz radiation.

  16. The system of RF beam control for electron gun

    NASA Astrophysics Data System (ADS)

    Barnyakov, A. M.; Chernousov, Yu. D.; Ivannikov, V. I.; Levichev, A. E.; Shebolaev, I. V.

    2015-06-01

    The system of RF control of three-electrode electron gun current is described. It consists of a source of microwave signal, coaxial line, coaxial RF switch and RF antenna lead. The system allows one to get the electron beam in the form of bunches with the frequency of the accelerating section to achieve the capture of particles in the acceleration mode close to 100%. The results of calculation and analysis of the elements of the system are presented. Characteristics of the devices are obtained experimentally. The results of using RF control in three-electrode electron gun at electron linear accelerator are described.

  17. Effect of electron beams during solar flares

    NASA Astrophysics Data System (ADS)

    Aboudarham, J.; Henoux, J. C.; Brown, J. C.; van den Oord, J.; van Driel-Gesztelyi, L.

    1990-12-01

    Electron bombardment of the solar atmosphere has two effects: one is to enhance hydrogen recombination emission, the other is to increase the opacity via an increase of H(-) population. The first effect is the most important in the upper part of the atmosphere, and the second in the lower part. It is predicted that, when enhanced absorption dominates in the part of the atmosphere where radiation originates, there will be a decrease in the white-light emission, leading to a 'negative flare', or 'black-light flare' short duration, not more than about 20 sec.

  18. Large area electron beam pumped krypton fluoride laser amplifier

    SciTech Connect

    Sethian, J.D.; Obenschain, S.P.; Gerber, K.A.; Pawley, C.J.; Serlin, V.; Sullivan, C.A.; Webster, W.; Deniz, A.V.; Lehecka, T.; McGeoch, M.W.; Altes, R.A.; Corcoran, P.A.; Smith, I.D.; Barr, O.C.

    1997-06-01

    Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm {times} 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high {times} 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier has been fully integrated into the Nike system and is used on a daily basis for laser-target experiments. {copyright} {ital 1997 American Institute of Physics.}

  19. Electron beam irradiation of Matricaria chamomilla L. for microbial decontamination

    NASA Astrophysics Data System (ADS)

    Nemţanu, Monica R.; Kikuchi, Irene Satiko; de Jesus Andreoli Pinto, Terezinha; Mazilu, Elena; Setnic, Silvia; Bucur, Marcela; Duliu, Octavian G.; Meltzer, Viorica; Pincu, Elena

    2008-05-01

    Wild chamomile (Matricaria chamomilla L.) is one of the most popular herbal materials with both internal and external use to cure different health disturbances. As a consequence of its origin, chamomile could carry various microbial contaminants which offer different hazards to the final consumer. Reduction of the microbial load to the in force regulation limits represents an important phase in the technological process of vegetal materials, and the electron beam treatment might be an efficient alternative to the classical methods of hygienic quality assurance. The purpose of the study was to analyze the potential application of the electron beam treatment in order to assure the microbial safety of the wild chamomile. Samples of chamomile dry inflorescences were treated in electron beam (e-beam) of 6 MeV mean energy, at room temperature and ambient pressure. Some loss of the chemical compounds with bioactive role could be noticed, but the number of microorganisms decreased as a function on the absorbed dose. Consequently, the microbial quality of studied vegetal material inflorescences was improved by e-beam irradiation.

  20. Focusing of a megavoltage electron beam in a medical accelerator

    NASA Astrophysics Data System (ADS)

    Friedrichs, P. B.; Konrad, G. T.

    1991-05-01

    Due to packaging constraints in the radiotherapy machine gantry of Siemens Mevatrons, the electron linac used in the lower energy models has a long drift tube between the end of the linae and the 270° achromatic bend assembly. Space charge effects cause the electron beam to grow so that it frequently impinges upon the entrance hole to the bend assembly. A compact solenoid has been designed that is effective in increasing the transmitted beam through the bend assembly by over 40%. A permanent magnet design proved to be unsuccessful because of high transverse fields within the magnet. Trajectory calculations obtained through the electron linac design code PARMELA (Public domain code supplied to Siemens Medical Laboratories, Inc. by L.M. Young, Los Alamos National Laboratories, Los Alamos, NM) support the experimentally observed results. Data is presented for several electron energies over the normal operating range of 4-6 MV photons from these Mevatrons.

  1. Creating and Steering Highly Directional Electron Beams in Graphene

    NASA Astrophysics Data System (ADS)

    Liu, Ming-Hao; Gorini, Cosimo; Richter, Klaus

    2017-02-01

    We put forward a concept to create highly collimated, nondispersive electron beams in pseudorelativistic Dirac materials such as graphene or topological insulator surfaces. Combining negative refraction and Klein collimation at a parabolic p n junction, the proposed lens generates beams, as narrow as the focal length, that stay focused over scales of several microns and can be steered by a magnetic field without losing collimation. We demonstrate the lens capabilities by applying it to two paradigmatic settings of graphene electron optics: We propose a setup for observing high-resolution angle-dependent Klein tunneling, and, exploiting the intimate quantum-to-classical correspondence of these focused electron waves, we consider high-fidelity transverse magnetic focusing accompanied by simulations for current mapping through scanning gate microscopy. Our proposal opens up new perspectives for next-generation graphene electron optics experiments.

  2. Radiation damage in zircon by high-energy electron beams

    SciTech Connect

    Jiang Nan; Spence, John C. H.

    2009-06-15

    Radiation damage induced by high-energy (200 keV) electron irradiation in zircon has been studied thoroughly using imaging, diffraction, and electron energy-loss spectroscopy techniques in transmission electron microscopy. Both structural and compositional changes during the damage were measured using the above techniques in real time. It was found that the damage was mainly caused by the preferential sputtering of O. The loss of O occurred initially within small sporadic regions with dimension of several nanometers, resulting in the direct transformation of zircon into Zr{sub x}Si{sub y}. These isolated patches gradually connect each other and eventually cover the whole area of the electron beam. These differ from the previous observations either in the self-irradiated natural and synthetic zircon or in ion-beam irradiated thin zircon specimen.

  3. Shaping single walled nanotubes with an electron beam

    SciTech Connect

    Zobelli, A.; Gloter, A.; Colliex, C.; Ewels, C. P.

    2008-01-15

    We show that electron irradiation in a dedicated scanning transmission microscope can be used as a nano-electron-lithography technique allowing the controlled reshaping of single walled carbon and boron nitride nanotubes. The required irradiation conditions have been optimized on the basis of total knock-on cross sections calculated within density functional based methods. It is then possible to induce morphological modifications, such as a local change of the tube chirality, by sequentially removing several tens of atoms with a nanometrical spatial resolution. We show that electron beam heating effects are limited. Thus, electron beam induced vacancy migration and nucleation might be excluded. These irradiation techniques could open new opportunities for nanoengineering a large variety of nanostructured materials.

  4. Singularities and internal rotational dynamics of electron beams

    NASA Astrophysics Data System (ADS)

    Velasco-Martínez, D.; Ibarra-Sierra, V. G.; Sandoval-Santana, J. C.; Cardoso, J. L.; Kunold, A.

    2016-12-01

    We study the internal rotational dynamics of electronic beams in relation to the phase singularities of their wave functions. Given their complex singularity structure, Hermite-Gaussian beams and other superpositions of Laguerre-Gaussian modes are studied here. We show that by inspecting the lowest nonvanishing terms of the wave function near the singularity, it is possible to infer the structure of the Bohmian streamlines. Conversely, starting from a map of the electron's Bohmian velocities, we demonstrate that it is possible to derive the form of the electron's wave function near the singularity. We outline a procedure that could yield an experimental method to determine the main parameters of the electron's wave function close to a singularity.

  5. Standing-Wave Free-Electron Laser Two-Beam Accelerator

    SciTech Connect

    Sessler, Andrew M.; Whittum, D.H.; Wurtele, Jonathan S.; Sharp, W.M.; Makowski, M.A.

    1991-02-01

    A free-electron laser (FEL) two-beam accelerator (TBA) is proposed, in which the FEL interaction takes place in a series of drive cavities, rather than in a waveguide. Each drive cavity is 'beat-coupled' to a section of the accelerating structure. This standing-wave TBA is investigated theoretically and numerically, with analyses included of microwave extraction, growth of the FEL signal through saturation, equilibrium longitudinal beam dynamics following saturation, and sensitivity of the microwave amplitude and phase to errors in current and energy. It is found that phase errors due to current jitter are substantially reduced from previous versions of the TBA. Analytic scalings and numerical simulations are used to obtain an illustrative TBA parameter set.

  6. A SIMPLE METHOD FOR MEASURING THE ELECTRON-BEAM MAGNETIZATION

    SciTech Connect

    Halavanau, A.; Qiang, G.; Wisniewski, E.; Ha, G.; Power, J.; Piot, P.

    2016-10-18

    There are a number of projects that require magnetized beams, such as electron cooling or aiding in “flat” beam transforms. Here we explore a simple technique to characterize the magnetization, observed through the angular momentum of magnetized beams. These beams are produced through photoemission. The generating drive laser first passes through microlens arrays (fly-eye light condensers) to form a transversely modulated pulse incident on the photocathode surface [1]. The resulting charge distribution is then accelerated from the photocathode. We explore the evolution of the pattern via the relative shearing of the beamlets, providing information about the angular momentum. This method is illustrated through numerical simulations and preliminary measurements carried out at the Argonne Wakefield Accelerator (AWA) facility are presented.

  7. Spin-valley splitting of electron beam in graphene

    NASA Astrophysics Data System (ADS)

    Song, Yu; Xie, Lei; Shi, Zhi-Gui; Li, Shun; Zhang, Jian

    2016-11-01

    We study spatial separation of the four degenerate spin-valley components of an electron beam in a EuO-induced and top-gated ferromagnetic/pristine/strained graphene structure. We show that, in a full resonant tunneling regime for all beam components, the formation of standing waves can lead sudden phase jumps ˜-π and giant lateral Goos-Hänchen shifts as large as the transverse beam width, while the interplay of the spin and valley imaginary wave vectors in the modulated regions can lead differences of resonant angles for the four spin-valley flavors, manifesting a spin-valley beam splitting effect. The splitting effect is found to be controllable by the gating and strain.

  8. Electron beam tuning of carrier concentrations in oxide nanowires

    NASA Astrophysics Data System (ADS)

    Ji, Hyunjin; Choi, Jaewan; Cho, Youngseung; Hwang, In-Sung; Kim, Sun-Jung; Lee, Jong-Heun; Roth, Siegmar; Kim, Gyu-Tae

    2011-07-01

    In spite of the attractive electrical properties of metal oxide nanowires, it is difficult to tune their surface states, notably the ionic adsorbents and oxygen vacancies, both of which can cause instability, degradation, and the irreproducibility or unrepeatable changes of the electrical characteristics. In order to control the surface states of the nanowires, electron beams were locally irradiated onto the channels of metal oxide nanowire field effect transistors. This high energy electron beam irradiation changed the electrical properties of the individual metal oxide nanowires, due to the removal of the negative adsorbents (O2-, O-). The detachment of the ionic adsorbents changes the charge states of the nanowires, resulting in the enhancement of the electrical conductance in n-type nanowires (ZnO, SnO2) and the degradation of the conductance in p-type nanowires (CuO). By investigating the changes in the electrical properties of nanowire devices in air or vacuum, with or without exposure to electron beams, the roles of the physisorbed water molecules or chemisorbed oxygen molecules can be independently understood. Unlike the electron beam irradiation, the vacuum enhanced the conductance of both n-type (ZnO, SnO2) and p-type (CuO) nanowires, due to the release of charges caused by the detachment of the polarized water molecules that were screening them from the surface of the nanowires, irrespective of the major carrier type. The electron beam irradiation technique has the potential to locally modulate the charge carriers in electronic nanowire devices, and the changes could be maintained with proper passivation for the long-term preservation of the device characteristics.

  9. Whistler-Mode Radiation from the Spacelab 2 Electron Beam.

    DTIC Science & Technology

    1985-11-27

    launched on July 29, 1985, a spacecraft called the Plasma Diagnostics Package (PDP) was released from the shuttle to survey the plasma environment around...be shown, the plasma wave emissions observed are remarkably similar to emissions detected by spacecraft flying through auroral electron beams. The PDP...the spacecraft and instruments, see Shawhan [19821. The electron gun on the shuttle is part of the Vehicle Charging and Potential (VCAP) experiment

  10. The Physics and Applications of High Brightness Electron Beams

    NASA Astrophysics Data System (ADS)

    Palumbo, Luigi; Rosenzweig, J.; Serafini, Luca

    2007-09-01

    Plenary sessions. RF deflector based sub-Ps beam diagnostics: application to FEL and advanced accelerators / D. Alesini. Production of fermtosecond pulses and micron beam spots for high brightness electron beam applications / S.G. Anderson ... [et al.]. Wakefields of sub-picosecond electron bunches / K.L.F. Bane. Diamond secondary emitter / I. Ben-Zvi ... [et al.]. Parametric optimization for an X-ray free electron laser with a laser wiggler / R. Bonifacio, N. Piovella and M.M. Cola. Needle cathodes for high-brightness beams / C.H. Boulware ... [et al.]. Non linear evolution of short pulses in FEL cascaded undulators and the FEL harmonic cascade / L. Giannessi and P. Musumeci. High brightness laser induced multi-meV electron/proton sources / D. Giulietti ... [et al.]. Emittance limitation of a conditioned beam in a strong focusing FEL undulator / Z. Huang, G. Stupakov and S. Reiche. Scaled models: space-charge dominated electron storage rings / R.A. Kishek ... [et al.]. High brightness beam applications: energy recovered linacs / G.A. Krafft. Maximizing brightness in photoinjectors / C. Limborg-Deprey and H. Tomizawa. Ultracold electron sources / O.J. Luiten ... [et al.]. Scaling laws of structure-based optical accelerators / A. Mizrahi, V. Karagodsky and L. Schächter. High brightness beams-applications to free-electron lasers / S. Reiche. Conception of photo-injectors for the CTF3 experiment / R. Roux. Superconducting RF photoinjectors: an overview / J. Sekutowicz. Status and perspectives of photo injector developments for high brightness beams / F. Stephan. Results from the UCLA/FNLP underdense plasma lens experiment / M.C. Thompson ... [et al.]. Medical application of multi-beam compton scattering monochromatic tunable hard X-ray source / M. Uesaka ... [et al.]. Design of a 2 kA, 30 fs RF-photoinjector for waterbag compression / S.B. Van Der Geer, O.J. Luiten and M.J. De Loos. Proposal for a high-brightness pulsed electron source / M. Zolotorev ... [et al

  11. Theory of low voltage annular beam free-electron lasers

    SciTech Connect

    Blank, M.; Freund, H.P.; Jackson, R.H.

    1995-12-31

    An nonlinear analysis of an annular beam propagating through a cylindrical waveguide in the presence of a helical wiggler and an axial guide field is presented. The analysis is based upon the ARACHNE simulation which is a non-wiggler-averaged slow-time-scale simulation code in which the electromagnetic field is represented as a superposition of the TE and TM modes in a vacuum waveguide, and the beam space-charge waves are represented as a superposition of Gould-Trivelpiece modes. The DC self-electric and self-magnetic fields are also included in the model. ARACHNE has been extensively benchmarked against experiments at MIT and NRL in the past with good agreement, but all of these experiments have dealt with solid electron beams and beam voltages in excess of 200 kV. In seeking to reduce the beam voltage requirements we now consider the effect of operation with an annular beam. One advantage to be obtained by using an annular beam is that, for a fixed beam current, the effect of the DC selffields (i.e., the space-charge depression in beam voltage) will be reduced relative to that of a solid beam. This facilitates beam transport in short period wigglers in which the transverse dimensions are also small. A specific example is under study which makes use of 55 kV/5A electron beam with inner and outer radii of 0.27 cm and 0.33 cm respectively. The wiggler amplitude is 250 G with a period of 0.9 cm. and guide fields up to 3 kG corresponding to Group I trajectories. The waveguide radius is chosen to correspond to grazing incidence for the fundamental mode in Ku-Band (12-18 GHz). Preliminary results indicate that efficiencies upwards of 10% are possible with no wiggler taper. In addition, the energy spread must be held below 0.1%, and the instantaneous bandwidth is found to be greater than 20%.

  12. PLASMA EMISSION BY COUNTER-STREAMING ELECTRON BEAMS

    SciTech Connect

    Ziebell, L. F.; Petruzzellis, L. T.; Gaelzer, R.; Yoon, P. H.; Pavan, J. E-mail: yoonp@umd.edu

    2016-02-10

    The radiation emission mechanism responsible for both type-II and type-III solar radio bursts is commonly accepted as plasma emission. Recently Ganse et al. suggested that type-II radio bursts may be enhanced when the electron foreshock geometry of a coronal mass ejection contains a double hump structure. They reasoned that the counter-streaming electron beams that exist between the double shocks may enhance the nonlinear coalescence interaction, thereby giving rise to more efficient generation of radiation. Ganse et al. employed a particle-in-cell simulation to study such a scenario. The present paper revisits the same problem with EM weak turbulence theory, and show that the fundamental (F) emission is not greatly affected by the presence of counter-streaming beams, but the harmonic (H) emission becomes somewhat more effective when the two beams are present. The present finding is thus complementary to the work by Ganse et al.

  13. Echo 7: Magnetospheric properties determined by artificial electron beams

    SciTech Connect

    Nemzek, R.J.

    1990-01-01

    The sounding rocket Echo 7 was launched from the Poker Flat Research Range. An on-board accelerator injected high-power electron beams into the magnetospheric tail near L = 6.5. After mirroring at the southern conjugate point, about 20 percent of the initial beam electrons returned to the North as Conjugate Echoes, where detectors (scintillators and spectrometers) on four subpayloads measured their energy and bounce time. The other 80 percent of the beam was pitch angle diffused by wave near the equatorial plane either into the conjugate atmosphere or up to mirror points above the payload. Comparison of measured values to calculations showed that the actual magnetosphere during the flight was well-described by the Tsyganenko-Usmanov model magnetosphere with a Kp value of 2- or 2+. Analysis of echo energies yielded values for the highly variable magnetospheric convection electric field.

  14. High Brightness Electron Beam Studies at the NSLS SDL

    SciTech Connect

    Qian,H.; Hidaka, Y.; Murphy, J. B.; Podobedov, B.; Seletskiy, S.; Shen, Y.; Yang, X.; Wang, X. J.; Tang, C. X.

    2009-05-04

    Experimental optimization of electron beam brightness at the NSLS SDL is reported in this paper. Using a high quantum efficiency (QE) Mg metal cathode and the S-band BNL-type RF gun, we have systematically studied electron beams transverse and longitudinal emittance. The measured thermal emittance for the Mg cathode is 0.85{+-}0.04 mm-mrad/mm, which contradicts the current thermal emittance model. For a 50 pC beam, measured normalized transverse and longitudinal RMS emittance are 0.6 mm-mrd and 5.2 ps-keV, respectively. The smallest projected transverse emittance observed for a 20 pC charge is 0.15 {+-} 0.02 mm-mrad.

  15. Plasma Emission by Counter-streaming Electron Beams

    NASA Astrophysics Data System (ADS)

    Ziebell, L. F.; Petruzzellis, L. T.; Yoon, P. H.; Gaelzer, R.; Pavan, J.

    2016-02-01

    The radiation emission mechanism responsible for both type-II and type-III solar radio bursts is commonly accepted as plasma emission. Recently Ganse et al. suggested that type-II radio bursts may be enhanced when the electron foreshock geometry of a coronal mass ejection contains a double hump structure. They reasoned that the counter-streaming electron beams that exist between the double shocks may enhance the nonlinear coalescence interaction, thereby giving rise to more efficient generation of radiation. Ganse et al. employed a particle-in-cell simulation to study such a scenario. The present paper revisits the same problem with EM weak turbulence theory, and show that the fundamental (F) emission is not greatly affected by the presence of counter-streaming beams, but the harmonic (H) emission becomes somewhat more effective when the two beams are present. The present finding is thus complementary to the work by Ganse et al.

  16. HOLLOW ELECTRON BEAM COLLIMATION FOR HL-LHC - EFFECT ON THE BEAM CORE

    SciTech Connect

    Fitterer, M.; Stancari, G.; Valishev, A.; Bruce, R.; Papadopoulou, S.; Papotti, G.; Pellegrini, D.; Pellegrini, S.; Valuch, D.; Wagner, J. F.

    2016-10-05

    Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.

  17. Science and applications of low-emittance electron beams

    SciTech Connect

    van Bibber, K

    2000-08-20

    The capability of making very low-emittance electron beams of temporally short, high charge bunches has opened up exciting new possibilities in basic and applied science. Two notable applications are high energy electron-positron linear colliders for particle physics, and fourth-generation light sources consisting of linac-driven Free-Electron Lasers (FEL), both of which represent significant programmatic potential for the Laboratory in the future. The technologies contributing to low-emittance electron beams and their applications, namely precision fabrication, ultra-short pulse lasers, and RF photocathode injectors, are all areas of Lab expertise, and the work carried out under this LDRD project further expanded our core-competency in advanced concept accelerators. Furthermore, high energy accelerators have become a cornerstone of the SBSS program, as illustrated by the recent development of proton radiography as a prime technology candidate for the Advanced Hydrotest Facility (AHF), which enhanced the significance of this project all the more. This was a one-year project to both advance the technology of, and participate in the science enabled by very low-emittance electron beams. The work centered around the two themes above, namely electron-positron linear colliders, and the new fourth-generation light sources. This work built upon previous LDRD investments, and was intended to emphasize accelerator physics experiments.

  18. Development of splitting convergent beam electron diffraction (SCBED).

    PubMed

    Houdellier, Florent; Röder, Falk; Snoeck, Etienne

    2015-12-01

    Using a combination of condenser electrostatic biprism with dedicated electron optic conditions for sample illumination, we were able to split a convergent beam electron probe focused on the sample in two half focused probes without introducing any tilt between them. As a consequence, a combined convergent beam electron diffraction pattern is obtained in the back focal plane of the objective lens arising from two different sample areas, which could be analyzed in a single pattern. This splitting convergent beam electron diffraction (SCBED) pattern has been tested first on a well-characterized test sample of Si/SiGe multilayers epitaxially grown on a Si substrate. The SCBED pattern contains information from the strained area, which exhibits HOLZ lines broadening induced by surface relaxation, with fine HOLZ lines observed in the unstrained reference part of the sample. These patterns have been analyzed quantitatively using both parts of the SCBED transmitted disk. The fine HOLZ line positions are used to determine the precise acceleration voltage of the microscope while the perturbed HOLZ rocking curves in the stained area are compared to dynamical simulated ones. The combination of these two information leads to a precise evaluation of the sample strain state. Finally, several SCBED setups are proposed to tackle fundamental physics questions as well as applied materials science ones and demonstrate how SCBED has the potential to greatly expand the range of applications of electron diffraction and electron holography.

  19. A compact terahertz free-electron laser with two gratings driven by two electron-beams

    NASA Astrophysics Data System (ADS)

    Liu, Weihao; Lu, Yalin; Wang, Lin; Jia, Qika

    2017-02-01

    We proposed and investigated a novel terahertz free-electron laser, which is based on two gratings driven by two electron-beams. Two gratings are symmetrically arranged to form an open-cavity. Two electron-beams generate special Smith-Purcell radiations, respectively, from two gratings. When radiation interferes constructively, operation modes of the open-cavity are excited and then amplified by beam-wave interactions. By means of particle-in-cell simulations, we have shown that, with compact equipments and available electron-beams, this scheme can generate radiation with power and efficiency being higher than those of majority radiation sources in the vicinity region of 1 THz. It can promisingly be developed as a high-power, high-efficiency, and compact terahertz source for practice.

  20. Adaptive robust control of longitudinal and transverse electron beam profiles

    NASA Astrophysics Data System (ADS)

    Rezaeizadeh, Amin; Schilcher, Thomas; Smith, Roy S.

    2016-05-01

    Feedback control of the longitudinal and transverse electron beam profiles are considered to be critical for beam control in accelerators. In the feedback scheme, the longitudinal or transverse beam profile is measured and compared to a desired profile to give an error estimate. The error is then used to act on the appropriate actuators to correct the profile. The role of the transverse feedback is to steer the beam in a particular trajectory, known as the "orbit." The common approach for orbit correction is based on approximately inverting the response matrix, and in the best case, involves regulating or filtering the singular values. In the current contribution, a more systematic and structured way of handling orbit correction is introduced giving robustness against uncertainties in the response matrix. Moreover, the input bounds are treated to avoid violating the limits of the corrector currents. The concept of the robust orbit correction has been successfully tested at the SwissFEL injector test facility. In the SwissFEL machine, a photo-injector laser system extracts electrons from a cathode and a similar robust control method is developed for the longitudinal feedback control of the current profile of the electron bunch. The method manipulates the angles of the crystals in the laser system to produce a desired charge distribution over the electron bunch length. This approach paves the way towards automation of laser pulse stacking.