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Sample records for 855-mev electron beam

  1. 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.

  2. 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.

  3. 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...

  4. 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)

  5. (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.

  6. Pulsed electron beam precharger

    SciTech Connect

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

    1991-01-01

    Electron beam precharging of a high resistivity aerosol was successfully performed under a range of experimental conditions during Quarter Six of the contract. The initial E-beam particle precharging experiments completed this term were designed to extend the efficiency of particle charging and collection using a fine, monodisperse aerosol at relatively large loadings in the FSU Electron Beam Precipitator wind tunnel. There are several reasons for doing this: (1) to re-establish a baseline performance criterion for comparison to other runs, (2) to test several recently upgraded or repaired subsystems, and (3) to improve upon the collection efficiency of the electron beam precipitator when testing precharging effectiveness with a very high resistivity, moderate-to-high dust concentration. In addition, these shakedown runs were used to determine a set of suitable operational parameters for the wind tunnel, the electrostatic collecting sections, and the MINACC E-beam accelerator. These parameters will normally be held constant while the precharging parameters are varied to produce an optimum particle charge. The electron beam precharging investigation performed during the period covered by Quarter Six used virtually the same experimental apparatus and procedures as in previous contract work, and these are described for review in this report. This investigation was part of an experimental effort which ran nearly continuously for nine months, encompassing work on the electrostatic collecting section, electron beam precharger, and particle charge-to-radius measuring apparatus. A summary of the work on dc electron beam precipitation is presented here.

  7. Sheet electron beam tester

    NASA Astrophysics Data System (ADS)

    Spear, Alexander Grenbeaux

    The DARPA HiFIVE project uses a pulsed electron sheet beam gun to power a traveling wave tube amplifier operating at 220 GHz. Presented is a method for characterizing the high current density 0.1 mm by 1 mm sheet electron beam. A tungsten tipped probe was scanned through the cross section of the sheet electron beam inside of a vacuum vessel. The probe was controlled with sub-micron precision using stepper motors and LabView computer control while boxcar averaging hardware sampled the pulsed beam. Matlab algorithms were used to interpret the data, calculate beam dimensions and current density, and create 2-dimensional cross section images. Full characterization of two separate HiFIVE sheet electron guns was accomplished and is also presented.

  8. Pulsed electron beam precharger

    SciTech Connect

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

    1989-01-01

    This is the fifth in a series of contracts and grants exploring the advanced particulate pollution control technology of electron beam precipitation. The chief goal of the current contract is to develop a laboratory scale electron beam precharger using a pulsed electric field to the proof-of-concept stage. Contract tasks leading to the achievement of this goal are generally divided up into two categories: tasks required to bring the Electron Beam Precipitator (EBP) test system up to an operational level for the contract work, and tasks concerning the actual experimental and analytical phase of the study. Not unexpectedly, the early portion of the contract duration will be devoted to the commissioning of the EBP and its many subsystems, while the latter portion will devote itself to testing the new pulsed electron beam precharger.

  9. Pulsed electron beam precharger

    SciTech Connect

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

    1990-01-01

    Electrostatic collection of a high resistivity aerosol using the Electron Beam Precipitator (EBP) collecting section was demonstrated during this reporting period (Quarter Five). Collection efficiency experiments were designed to confirm and extend some of the work performed under the previous contract. The reason for doing this was to attempt to improve upon the collection efficiency of the precipitator alone when testing with a very high resistivity, moderate-to-high concentration dust load. From the collector shakedown runs, a set of suitable operational parameters were determined for the downstream electrostatic collecting sections of the Electron Beam Precipitator wind tunnel. These parameters, along with those for the MINACC electron beam, will generally be held constant while the numerous precharging parameters are varied to produce an optimum particle charge. The electrostatic collector experiments were part of a larger, comprehensive investigation on electron beam precharging of high resistivity aerosol particles performed during the period covered by Quarters Five, Six, and Seven. This body of work used the same experimental apparatus and procedures and the experimental run period lasted nearly continuously for six months. A summary of the Quarter Five work is presented in the following paragraphs. Section II-A of TPR 5 contains a report on the continuing effort which was expended on the modification and upgrade of the pulsed power supply and the monitoring systems prior to the initiation of the electron beam precharging experimental work.

  10. Pulsed electron beam precharger

    SciTech Connect

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

    1991-01-01

    Electron beam precharging of a high resistivity aerosol was successfully demonstrated during this reporting period (Quarters Five and Six). The initial E-beam particle precharging experiments completed this term were designed to confirm and extend some of the work performed under the previous contract. There are several reasons for doing this: (1) to re-establish a baseline performance criterion for comparison to other runs, (2) to test several recently upgraded or repaired subsystems, and (3) to improve upon the collection efficiency of the electron beam precipitator when testing precharging effectiveness with a very high resistivity, moderate-to-high concentration dust load. In addition, these shakedown runs were used to determine a set of suitable operational parameters for the wind tunnel, the electrostatic collecting sections, and the MINACC E-beam accelerator. These parameters will generally be held constant while the precharging parameters are varied to produce an optimum particle charge.

  11. 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.

  12. Landsat electron beam recorder

    NASA Astrophysics Data System (ADS)

    Grosso, P. F.; Whitley, J. P.

    A minicomputer-controlled electron beam recorder (EBR) presently in use at the Brazilian Government's Institute De Pesquisas Espaclais (INPE) satellite ground station is described. This 5-in.-film-size EBR is used to record both Landsat and SPOT satellite imagery in South America. A brief electron beam recorder technology review is presented. The EBR is capable of recording both vector and text data from computer-aided design, publishing, and line art systems and raster data from image scanners, raster image processors (RIPS), halftone/screen generators, and remote image sensors. A variety of image formats may be recorded on numerous film sizes (16 mm, 35 mm, 70 mm, 105 mm, 5-in, 5.5-in., and 9.5-in.). These recordings are used directly or optically enlarged depending on the final product.

  13. Pulsed electron beam precharger

    NASA Astrophysics Data System (ADS)

    Finney, W. C.

    A short review of electron beam particle precharging using a pulsed electric field is presented. The design and installation is detailed of a remote focusing gear train which will allow much greater control over the particle charge measurement capability of the charge vs. radius apparatus. 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. The basic effort is to optimize the removal efficiency for fly ash particles.

  14. 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.

  15. Electron Cooling of Bunched Beams

    SciTech Connect

    Uesugi, T.; Noda, K.; Syresin, E.; Meshkov, I.; Shibuya, S.

    2006-03-20

    Experiments of electron cooling have been done with the HIMAC synchrotron in NIRS. Limitation on cooled beam-sizes in longitudianl and transverse spaces were measured. The effect of space-charge field and intra-beam scattering are investigated.

  16. Electron Beam Ablation and Deposition

    NASA Astrophysics Data System (ADS)

    Kovaleski, S. D.; Gilgenbach, R. M.; Ang, L. K.; Lau, Y. Y.

    1997-11-01

    Ablation of fused silica, titanium nitride, and boron nitride with a channel spark electron beam is being studied. The channel spark is a low energy (15-20kV), high current (1600A) electron beam source developed at KFK(G. Muller and C. Schultheiss, Proc. of Beams `94, Vol. II, p833). This is a pseudospark device which operates in the ion focused regime of electron beam transport. For this reason, a low pressure (10-15mTorr of Ar) background gas is used to provide electron beam focusing. Plume composition and excitation has been studied via optical emission spectroscopy. Ablation has also been imaged photographically. Electron density gradients and densities are being studied through laser deflection. Film deposition experiments are also being performed. Electron transport and energy deposition in metals are being simulated in the ITS-TIGER code(Sandia Report No. SAND 91-1634).

  17. Focusing Electron Beams at SLAC.

    ERIC Educational Resources Information Center

    Taylor, Richard L.

    1993-01-01

    Describes the development of a set of magnets that focus high-energy electron and positron beams causing them to collide, annihilate each other, and generate new particles. Explains how dipoles bend the beam, how quadrupoles focus the beam, how the focal length is calculated, and the superconducting final focus. (MDH)

  18. Collimation with hollow electron beams.

    PubMed

    Stancari, G; Valishev, A; Annala, G; Kuznetsov, G; Shiltsev, V; Still, D A; Vorobiev, L G

    2011-08-19

    A novel concept of controlled halo removal for intense high-energy beams in storage rings and colliders is presented. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as a tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collimator extends conventional collimation systems beyond the intensity limits imposed by tolerable losses. The concept was tested experimentally at the Fermilab Tevatron proton-antiproton collider. The first results on the collimation of 980-GeV antiprotons are presented. PMID:21929171

  19. Electron Beam Dump Particle Search

    SciTech Connect

    Crisler, M.; Fenker, H.; Leedom, I.; Pordes, S.; /Fermilab

    1986-05-30

    The debate over the existence of a new particle postulated to explain the narrow positron spectra seen in heavy ion collisions has focused attention on a region of mass/lifetime where such a particle may exist and yet would not have been seen. To obtain the best possible sensitivity to elementary particles coupling to the electron in this unexplored region, we propose an electron beam dump experiment which will make parasitic use of the newly constructed wide band electron beam.

  20. 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. PMID:23426323

  1. Electron Beam Ablation of Metals

    NASA Astrophysics Data System (ADS)

    Kovaleski, S. D.; Gilgenbach, R. M.; Rintamaki, J. I.; Ang, L. K.; Spindler, H. L.; Cohen, W. E.; Lau, Y. Y.; Lash, J. S.

    1996-10-01

    An experiment has recently been devised for material ablation using a channelspark electron beam. The ultimate goal of this experiment is to deposit thin films by electron beam ablation. The channelspark is a pseudospark device developed by Forschungszentrum Karlsruhe (G. Muller, C. Schultheiss, Proc. of Beams, 2, 833(1994)) for production of high current, low energy electron beams. The channelspark has the following operating parameters: a 15-20kV accelerating potential and measured source current of <2000A. Initial experiments have concentrated on characterizing ion-focused electron beam current transport through the necessary background fill gas (typically 5-50 mTorr of Argon). Ablation of Al, Fe, and Ti is being studied with spectroscopy and electron beam current diagnostics. Physical beam target damage is also being investigated and compared to laser ablated targets. Simulations of electron transport and energy deposition are being conducted via the ITS-TIGER code (Sandia Report No. SAND 91-1634) developed at Sandia National Laboratory.

  2. 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.

  3. 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.

  4. 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.

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

    SciTech Connect

    Becker, Reinard; Kester, Oliver

    2010-02-15

    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.

  6. Electron beam modeling on LTX

    NASA Astrophysics Data System (ADS)

    Szalkowski, Gregory; Majeski, Richard; Schmitt, John

    2014-10-01

    The lithium tokamak experiment (LTX) is a low aspect ratio tokamak with a steel clad copper shell that can be heated to 300-400 °C and coated with lithium. The lithium coating has been shown to decrease impurities in the plasma and decrease the recycling coefficient, improving plasma performance. The coating is applied to the walls by heating the shells, then using an electron beam to evaporate a pool of lithium located at the bottom of the shell. The beam is steered using the magnetic field generated by the field coils. This method allows for rapid evaporation of the lithium, producing a 50-100 nm coating in approximately 5 minutes. The current electron beam system can only coat half of the shell surface. A new electron beam system has been installed on LTX to coat the remaining shell surface. A model of this electron gun has been created using the AMaze program series (Field Precision LCC). The model will be used to find the magnetic fields needed to steer the electron beam produced by the gun to the lithium pool. The model will also show the electropotential produced both at the electron gun head and in the vessel. The model may also be used to find the dispersion of the beam and therefore the effective power density of the beam as it impacts the lithium pool. Supported by US DOE Contracts DE-AC02-09CH11466 and DE-AC52-07NA27344 and in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship.

  7. 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.

  8. Electron beam controller. [using magnetic field to refocus spent electron beam in microwave oscillator tube

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G. (Inventor)

    1973-01-01

    An electron beam device which extracts energy from an electron beam before the electrons of the beam are captured by a collector apparatus is described. The device produces refocusing of a spent electron beam by minimizing tranverse electron velocities in the beam where the electrons, having a multiplicity of axial velocities, are sorted at high efficiency by collector electrodes.

  9. 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.

  10. 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.

  11. 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.

  12. Vortices in relativistic electron beams

    PubMed

    Jovanovic; Fedele; Shukla

    2000-08-01

    We demonstrate that a relativistic electron beam is properly described in the moving frame by the electron-magnetohydrodynamic equations of plasma physics. For large beam currents, the accelerator magnetic field is expected to be unstable to the fast magnetic reconnection. We present a plausible saturated state of the fast reconnection, in the form of a complex vortex pattern. The nonlinear dispersion equations of the vortex are derived and the relationship between the vortex structure and the background magnetic field is discussed. PMID:11088759

  13. 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.

  14. 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.

  15. 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…

  16. APPARATUS FOR ELECTRON BEAM HEATING CONTROL

    DOEpatents

    Jones, W.H.; Reece, J.B.

    1962-09-18

    An improved electron beam welding or melting apparatus is designed which utilizes a high voltage rectifier operating below its temperature saturation region to decrease variations in electron beam current which normally result from the gas generated in such apparatus. (AEC)

  17. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-04-01

    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*{sub 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.

  18. 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.

  19. 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.

  20. Modern developments in electron-beam fluorescence

    NASA Astrophysics Data System (ADS)

    Cattolica, Robert J.

    Recent developments in the area of electron-beam fluorescence are discussed with special attention given to the experience in the use of the electron-beam fluorescence in flight research. A new measurement approach, called electron-photon fluorescence (EPF), is described, and it is shown that EPF offers the potential of overcoming some of the disadvantages of electron-beam fluorescence in high-density flows. Examples of using the EPF technique are presented.

  1. Modern developments in electron-beam fluorescence

    NASA Technical Reports Server (NTRS)

    Cattolica, Robert J.

    1991-01-01

    Recent developments in the area of electron-beam fluorescence are discussed with special attention given to the experience in the use of the electron-beam fluorescence in flight research. A new measurement approach, called electron-photon fluorescence (EPF), is described, and it is shown that EPF offers the potential of overcoming some of the disadvantages of electron-beam fluorescence in high-density flows. Examples of using the EPF technique are presented.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Optics of electron beam in the Recycler

    SciTech Connect

    Burov, Alexey V.; Kazakevich, G.; Kroc, T.; Lebedev, V.; Nagaitsev, S.; Prost, L.; Pruss, S.; Shemyakin, A.; Sutherland, M.; Tiunov, M.; Warner, A.; /Fermilab /Novosibirsk, IYF

    2005-11-01

    Electron cooling of 8.9 GeV/c antiprotons in the Recycler ring (Fermilab) requires high current and good quality of the DC electron beam. Electron trajectories of {approx}0.2 A or higher DC electron beam have to be parallel in the cooling section, within {approx}0.2 mrad, making the beam envelope cylindrical. These requirements yielded a specific scheme of the electron transport from a gun to the cooling section, with electrostatic acceleration and deceleration in the Pelletron. Recuperation of the DC beam limits beam losses at as tiny level as {approx}0.001%, setting strict requirements on the return electron line to the Pelletron and a collector. To smooth the beam envelope in the cooling section, it has to be linear and known at the transport start. Also, strength of the relevant optic elements has to be measured with good accuracy. Beam-based optic measurements are being carried out and analyzed to get this information. They include beam simulations in the Pelletron, differential optic (beam response) measurements and simulation, beam profile measurements with optical transition radiation, envelope measurements and analysis with orifice scrapers. Current results for the first half-year of commissioning are presented. Although electron cooling is already routinely used for pbar stacking, its efficiency is expected to be improved.

  11. Optics of Electron Beam in the Recycler

    SciTech Connect

    Burov, A.; Kroc, T.; Lebedev, V.; Nagaitsev, S.; Prost, L.; Pruss, S.; Shemyakin, A.; Sutherland, M.; Warner, A.; Kazakevich, G.; Tiunov, M.

    2006-03-20

    Electron cooling of 8.9 GeV/c antiprotons in the Recycler ring (Fermilab) requires high current and good quality of the DC electron beam. Electron trajectories of {approx}0.2 A or higher DC electron beam have to be parallel in the cooling section, within {approx} 0.2 mrad, making the beam envelope cylindrical. These requirements yielded a specific scheme of the electron transport from a gun to the cooling section, with electrostatic acceleration and deceleration in the Pelletron. Recuperation of the DC beam limits beam losses at as tiny level as {approx}0.001%, setting strict requirements on the return electron line to the Pelletron and a collector. To smooth the beam envelope in the cooling section, it has to be linear and known at the transport start. Also, strength of the relevant optic elements has to be measured with good accuracy. Beam-based optic measurements are being carried out and analysed to get this information. They include beam simulations in the Pelletron, differential optic (beam response) measurements and simulation, beam profile measurements with optical transition radiation, envelope measurements and analysis with orifice scrapers. Current results for the first half-year of commissioning are presented. Although electron cooling is already routinely used for pbar stacking, its efficiency is expected to be improved.

  12. 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.

  13. 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.

  14. Electron beam coherence measurements using diffracted beam interferometry/holography.

    PubMed

    Herring, Rodney A

    2009-06-01

    The intensity and coherence of elastically and inelastically scattered electrons have been studied by the interference of electron-diffracted beams using a method of diffracted beam interferometry/holography (DBI/H). In the interferograms produced, fringes were found to exist from low to high scattering angles. The intensity and coherence of the fringes are useful for understanding the contrast mismatch between experimental and simulated images found in atomic resolution images of crystals produced by transmission electron microscopy (TEM) and annular dark-field (ADF) scanning transmission electron microscopy (STEM). The fringes disappear when the interfering beams are separated from an exact overlay position, which produces a measurement of the beam's lateral coherence and holds promise for measuring the coherence of the respective quasi-particles associated with the energy loss electrons. PMID:19141592

  15. 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.

  16. 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.

  17. BEAM-BEAM SIMULATIONS FOR THE ERHIC ELECTRON RING.

    SciTech Connect

    MONTAG, C.

    2005-05-16

    To study collisions between polarized electrons and heavy ions or polarized protons at high energy, adding a 10 GeV electron storage ring to the existing RHIC facility is currently under consideration. To achieve high luminosities of several 10{sup 33} cm{sup -2} sec{sup -1} range, a vertical beam-beam tuneshift parameter of {zeta}{sub y} = 0.08 is required for the electron beam. Simulation studies are being performed to study the feasibility of this high tuneshift parameter and explore the potential for even higher tuneshifts. Recent results of these studies are presented.

  18. Electron beam selectively seals porous metal filters

    NASA Technical Reports Server (NTRS)

    Snyder, J. A.; Tulisiak, G.

    1968-01-01

    Electron beam welding selectively seals the outer surfaces of porous metal filters and impedances used in fluid flow systems. The outer surface can be sealed by melting a thin outer layer of the porous material with an electron beam so that the melted material fills all surface pores.

  19. Electron beam sterilisation of heterogeneous medical devices

    NASA Astrophysics Data System (ADS)

    Sadat, T.; Morisseau, MrD.; Ross, MissA.

    1993-07-01

    Electron beam radiation is used in the sterilisation of medical disposable devices. High energy, 10 MeV, electron beam linear accelerators are in use worldwide for this purpose. The dose distribution achieved in the products treated influences the efficiency of treatment. This paper looks at the dose distribution achieved with such machines and the methods used to define it in heterogeneous products.

  20. Separating Isotopes With Laser And Electron Beams

    NASA Technical Reports Server (NTRS)

    Trajmar, Sandor

    1989-01-01

    Need for second laser eliminated. In scheme for separation of isotopes, electrons of suitable kinetic energy ionize specific isotope excited by laser beam in magnetic field. Ionization by electron beams cheap and efficient in comparison to ionization by laser beams, and requires no special technical developments. Feasibility of new scheme demonstrated in selective ionization of Ba138, making possible separation of isotope from Ba isotopes of atomic weight 130, 132, 134, 135, 136, and 137.

  1. Electron beam curing of polymer matrix composites

    SciTech Connect

    Janke, C.J.; Wheeler, D.; Saunders, C.

    1998-01-08

    The purpose of the CRADA was to conduct research and development activities to better understand and utilize the electron beam PMC curing technology. This technology will be used to replace or supplement existing PMC thermal curing processes in Department of Energy (DOE) Defense Programs (DP) projects and American aircraft and aerospace industries. This effort involved Lockheed Martin Energy Systems, Inc./Lockheed Martin Energy Research Corp. (Contractor), Sandia National Laboratories, and ten industrial Participants including four major aircraft and aerospace companies, three advanced materials companies, and three electron beam processing organizations. The technical objective of the CRADA was to synthesize and/or modify high performance, electron beam curable materials that meet specific end-use application requirements. There were six tasks in this CRADA including: Electron beam materials development; Electron beam database development; Economic analysis; Low-cost Electron Beam tooling development; Electron beam curing systems integration; and Demonstration articles/prototype structures development. The contractor managed, participated and integrated all the tasks, and optimized the project efforts through the coordination, exchange, and dissemination of information to the project participants. Members of the Contractor team were also the principal inventors on several electron beam related patents and a 1997 R and D 100 Award winner on Electron-Beam-Curable Cationic Epoxy Resins. The CRADA achieved a major breakthrough for the composites industry by having successfully developed high-performance electron beam curable cationic epoxy resins for use in composites, adhesives, tooling compounds, potting compounds, syntactic foams, etc. UCB Chemicals, the world`s largest supplier of radiation-curable polymers, has acquired a license to produce and sell these resins worldwide.

  2. Spin transport in tilted electron vortex beams

    NASA Astrophysics Data System (ADS)

    Basu, Banasri; Chowdhury, Debashree

    2014-12-01

    In this paper we have enlightened the spin related issues of tilted Electron vortex beams. We have shown that in the skyrmionic model of electron we can have the spin Hall current considering the tilted type of electron vortex beam. We have considered the monopole charge of the tilted vortex as time dependent and through the time variation of the monopole charge we can explain the spin Hall effect of electron vortex beams. Besides, with an external magnetic field we can have a spin filter configuration.

  3. 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.

  4. Intense steady state electron beam generator

    DOEpatents

    Hershcovitch, A.; Kovarik, V.J.; Prelec, K.

    1990-07-17

    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. 2 figs.

  5. 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.

  6. Generation of Nondiffracting Electron Bessel Beams

    NASA Astrophysics Data System (ADS)

    Grillo, Vincenzo; Karimi, Ebrahim; Gazzadi, Gian Carlo; Frabboni, Stefano; Dennis, Mark R.; Boyd, Robert W.

    2014-01-01

    Almost 30 years ago, Durnin discovered that an optical beam with a transverse intensity profile in the form of a Bessel function of the first order is immune to the effects of diffraction. Unlike most laser beams, which spread upon propagation, the transverse distribution of these Bessel beams remains constant. Electrons also obey a wave equation (the Schrödinger equation), and therefore Bessel beams also exist for electron waves. We generate an electron Bessel beam by diffracting electrons from a nanoscale phase hologram. The hologram imposes a conical phase structure on the electron wave-packet spectrum, thus transforming it into a conical superposition of infinite plane waves, that is, a Bessel beam. We verify experimentally that these beams can propagate for 0.6 m without measurable spreading and can also reconstruct their intensity distributions after being partially obstructed by an obstacle. Finally, we show by numerical calculations that the performance of an electron microscope can be increased dramatically through use of these beams.

  7. 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.

  8. Survey on electron beam processing technologies

    NASA Astrophysics Data System (ADS)

    Yasui, S.; Sunabe, K.; Inaba, T.

    1990-06-01

    The developing situation is studied of electron beam processing technologies and the future problems are shown when these are utilized for electric power utilities. When an electron beam is used as a heating source by focussing, the electron beam has features of high focusability, high controllability and high energy density, so that the electron beam is used for parts requiring high quality processing from micro machining, case hardening, and welding to melting furnaces of metals of high melting point. Presently is necessary to hold ultra high voltage for acceleration and high vacuum because of lower current. Since the processing capability with high energy density is high and the energy consumption efficiency is also high for the chemical field using the high energy density of the electron beam, the application are researched in the field from sterilization of medical instruments, sterilization of sludge, through food processing, improvement of thermal resistance of insulated wires to flue gas irradiation to desulfurize and denitrify. But a practical use is not yet realized because of small current of electron beam. Therefore, the largest technological problem may be the development of high current electron gun and the beam control systems.

  9. REVIEW: Review of electron beam therapy physics

    NASA Astrophysics Data System (ADS)

    Hogstrom, Kenneth R.; Almond, Peter R.

    2006-07-01

    For over 50 years, electron beams have been an important modality for providing an accurate dose of radiation to superficial cancers and disease and for limiting the dose to underlying normal tissues and structures. This review looks at many of the important contributions of physics and dosimetry to the development and utilization of electron beam therapy, including electron treatment machines, dose specification and calibration, dose measurement, electron transport calculations, treatment and treatment-planning tools, and clinical utilization, including special procedures. Also, future changes in the practice of electron therapy resulting from challenges to its utilization and from potential future technology are discussed.

  10. Plasma heating with crossing relativistic electron beams

    NASA Astrophysics Data System (ADS)

    Ratan, Naren; Sircombe, Nathan; Ceurvorst, Luke; Kasim, Muhammad; Sadler, James; Bingham, Robert; Trines, Raoul; Norreys, Peter

    2015-11-01

    Plasma heating by relativistic electron beams is a powerful tool with applications including the heating of inertial confinement fusion targets and the study of matter in extreme conditions. We discuss the use of two relativistic electron beams to efficiently heat the plasma ions where the beams cross by using beam-plasma instabilities and non-linear wave coupling between Langmuir and ion-acoustic waves. Energy from the electron beams is coupled to the plasma ions as the beams become unstable and drive Langmuir waves which couple non-linearly to ion-acoustic waves which are then damped . Results of linear growth rate calculations are presented for the system of two crossing electron beams demonstrating a broad spectrum of unstable modes. Relativistic Vlasov-Maxwell simulations in two space and two momentum dimensions have been performed which demonstrate the non-linear coupling of the electron beam energy into ion-acoustic waves and the energy cascade to the background ions. Time-frequency analysis is applied to analyze the non-linear coupling between Langmuir and ion-acoustic waves in wave phase space. Structural properties of the strong turbulence produced at late times are analyzed.

  11. 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.

  12. 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

  13. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, Changbiao

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically transported 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.

  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. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. The Electron Beam Ion Source (EBIS)

    ScienceCinema

    Brookhaven Lab

    2010-01-08

    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. 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 ...

  2. 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.

  3. 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

  4. Characterization Of A Wakefield Accelerated Electron Beam

    NASA Astrophysics Data System (ADS)

    Guèye, Paul; Keppel, Cynthia; Lane, Bianca; Owens, Judy; Torrence, Rickey; Saleh, Ned; Umstadter, Don; Zhang, Ping; Ent, Rolf; Assamagan, Kétévi

    2001-10-01

    With the advancement of femtosecond Terawatt lasers, there has been great interest in their ability of accelerating electrons to high energy within short distances; this effect originating from the GeV/cm gradient created in the plasma (compared to conventional RF systems). We report on new experimental results obtained from a 400 fs/4 J-laser plasma driven electron beam. The data were collected by means of a ~ 3 m QQ¯QD spectrometer especially designed for that experiment. A 32× 16 fiber array detector, along with a scintillating LANEX screen and a Faraday cup were used to detect the electrons, and for charge monitoring. The momentum and spatial distributions of the beam were reconstructed. The results are consistent with a previous experiment, and compatible with a GEANT simulation used for background estimation due primarily to secondaries induced by electron-beam pipe collisions. We also report on the extracted emittance of the beam for the corresponding momentum range.

  5. Electron beam, laser beam and plasma arc welding studies

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

  6. 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)

  7. Electron beam ion sources and traps (invited)

    NASA Astrophysics Data System (ADS)

    Becker, Reinard

    2000-02-01

    The electron beam method of stepwise ionization to highest charge states has found applications in electron beam ion sources (EBISs) for accelerators and atomic physics collision experiments as well as in electron beam ion traps (EBITs) for x-ray and mass spectroscopy. A dense and almost monoenergetic electron beam provides a unique tool for ionization, because radiative recombination by slow electrons is negligible and charge exchange is almost avoided in ultrahigh vacua. These are essential differences to electron cyclotron resonance ion sources with inevitable low energy electrons and comparatively high gas pressure. The distinction between EBIS and EBIT as genuine devices has become meaningless, because EBISs may work as traps and almost all EBITs are feeding beamlines for external experiments. More interesting is to note the diversification of these devices, which demonstrates that a matured technology is finding dedicated answers for different applications. At present we may distinguish six major lines of development and application: high current EBISs for upcoming hadron colliders, super EBITs in the energy range above 300 keV for quantum electrondynamics tests, inexpensive and small EBISTs for atomic physics studies, a highly efficient EBIS with oscillating electrons, MEDEBIS for tumor therapy with C6+, and charge breeding in facilities for exotic radioactive beams.

  8. Effective Electron Beam Injection With Broad Energy Initial Beam

    SciTech Connect

    Cooley, J.H.; Hubbard, R.F.; Gordon, D.F.; Ting, A.; Sprangle, P.; Zigler, A.

    2004-12-07

    Laser Wakefield Accelerators (LWFA), in the resonant regime, require use of an injected electron beam. Several optical methods for generating electron bunches exist e.g., Laser Ionization and Ponderomotive Acceleration (LIPA) and Self-Modulated LWFA among others. Each of these schemes produces an electron bunch with a characteristic energy distribution. We examine the trapping characteristics in a resonant LWFA for an injection electron beam with a broad energy spread that can be characterized using a Boltzmann distribution with an 'effective temperature'. We present results of both analytic calculations and simulations which provide a methodology for optimizing the resulting accelerated electron bunch characteristics i.e., energy and energy spread, for a given LWFA configuration.

  9. Electron-beam furnace with magnetic stabilization

    SciTech Connect

    Harker, H.R.; Knecht, J.A. II

    1986-10-07

    This patent describes an electron-beam comprising: a. An evacuable chamber having a port for coupling the chamber to vacuum pump means; b. a trough-shaped hearth within the chamber for holding material to be melted, the hearth having a spout for issuing a flow of molten material therefrom; c. a crucible positioned within the chamber for receiving molten material flowing from the hearth; d. one or more electron guns each for producing an energetic beam of electrons, each electron gun being positioned a relatively large distance away from the hearth and the crucible; e. magnetic beam deflection means forming an integral part of each electron gun for scanning and shaping the beam produced thereby across the hearth or the crucible; and f. magnetic means adjacent to the hearth and the crucible for producing a relatively weak magnetic field in the vicinity of the hearth and the crucible for preventing erratic deflections of the scanning electron beams without significantly altering the trajectories of such beams.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, Changbiao.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically transported 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.

  18. 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.

  19. Nonlinear wave scattering and electron beam relaxation

    NASA Technical Reports Server (NTRS)

    Muschietti, L.; Dum, C. T.

    1991-01-01

    The role played by nonlinear scattering during the relaxation of a warm electron beam is investigated through a numerical code based on kinetic equations. The code encompasses the quasi-linear wave-electron interaction and wave-wave scattering off ion clouds. Ions with velocities 2 nu sub i (nu sub i being the ion thermal velocity) are found to be the most efficient for scattering the Langmuir waves off their polarization clouds. The transfer rate of the spectrum out of resonance with the beam is larger by a factor 3 compared to usual estimates. The changes produced in the dispersion relation by the presence of the beam electrons dramatically alter the characteristics of the secondary spectrum. In a late phase the classic condensate K of about 0 is depleted, with the formation of a new condensate in resonance with the flat-topped beam distribution, which follows from the fact that the mere presence of the beam electrons creates a minimum in the frequency-wave-number relation. For strong and slow beams, the predictions of the code are found to be in excellent agreement with the results of the particle simulation if a dispersion relation that includes the beam is used.

  20. Electron beam size measurements in the Fermilab Electron Cooling System

    SciTech Connect

    Kroc, T.K.; Burov, A.V.; Bolshakov, T.B.; Shemyakin, A.; Seletskiy, S.M.; /Rochester U.

    2005-09-01

    The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide maximum cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper will focus on results of these measurements of the beam size and the difficulties in making those measurements.

  1. Electron Beam Size Measurements in the Fermilab Electron Cooling System

    SciTech Connect

    Kroc, T. K.; Burov, A. V.; Bolshakov, T. B.; Shemyakin, A.; Seletskiy, S. M.

    2006-03-20

    The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide maximum cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper will focus on results of these measurements of the beam size and the difficulties in making those measurements.

  2. 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.

  3. Theory of helical electron beams in gyrotrons

    SciTech Connect

    Kuftin, A.N.; Lygin, V.K.; Manuilov, V.N.; Raisky, B.V.; Solujanova, E.A.; Tsimring, S.E.

    1993-04-01

    Helical electron beams (HEB) with disturbed axial symmetry of currents density and HEB with locking electrons in magnetic trap are described. The theory of magnetron injection gun (MIG) in space-charge limited current is developed. Systems on permanent magnets forming HEB are considered. 30 refs., 12 figs., 5 tabs.

  4. 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. PMID:25659003

  5. Parameterization of electron beam output factor.

    PubMed

    Akino, Yuichi; Zhu, Timothy C; Das, Indra J

    2015-06-01

    Electron beam dose distribution is dependent on the beam energy and complicated trajectory of particles. Recent treatment planning systems using Monte Carlo calculation algorithm provide accurate dose calculation. However, double check of monitor units (MUs) based on an independent algorithm is still required. In this study, we have demonstrated single equation that reproduces the measured relative output factor (ROF) that can be used for MU calculation for electron radiotherapy. Electron beams generated by an iX (Varian Medical Systems) and a PRIMUS (Siemens) accelerator were investigated. For various energies of electron beams, the ROF at respective dmax were measured using diode detector in a water phantom at SSD of 100 cm. Curve fitting was performed with an exponential generalized equation ROF = α(β - e(-γR)) including three variables (α, β, γ) as a function of field radius and electron energy. The correlation coefficients between the ROF measured and that calculated by the equation were greater than 0.998. For ROF of Varian electron beams, the average values of all fitting formulas were applied for two of the constants; α and β. The parameter γ showed good agreement with the quadratic approximation as a function of mean energy at surface (E0). The differences between measured and calculated ROF values were within ± 3% for beams with cutout radius of ≥ 1.5 cm for electron beams with energies from 6 MeV to 15 MeV. The proposed formula will be helpful for double-check of MUs, as it requires minimal efforts for MU calculation. PMID:25726475

  6. Green coffee decontamination by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Nemtanu, Monica R.; Brasoveanu, Mirela; Grecu, Maria Nicoleta; Minea, R.

    2005-10-01

    Microbiological load of green coffee is a real problem considering that it is extremely sensitive to contamination. Irradiation is a decontamination method for a lot of foodstuffs, being a feasible, very effective and environment friendly one. Beans and ground green coffee were irradiated with electron beams up to 40 kGy. Microbial load, rheological behavior, electron paramagnetic resonance (EPR) and visible spectroscopy were carried out. The results show that electron beam irradiation of green coffee could decontaminate it without severe changes in its properties.

  7. 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.

  8. 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.

  9. Radiative cooling of relativistic electron beams.

    SciTech Connect

    Huang, Z.

    1999-04-14

    Radiative cooling is a natural and effective method of phase-space cooling for stored electron beams. In electron storage rings the average effects of synchrotron radiation from the bending magnets cause the beam emittances in all three degrees of freedom to damp towards equilibria, determined by the fluctuating nature of quantum emissions. In this paper, they show that the radiation damping in a focusing system is fundamentally different from that in a bending system. Quantum excitation to the transverse dimensions is absent in a straight, continuous focusing channel, and is exponentially suppressed in a focusing-dominated ring. Thus, the transverse normalized emittances in such systems can in principle be damped to the Compton wavelength of the electron, limited only by the Heisenberg Uncertainty Principle. In addition, they investigate methods of rapid damping such as radiative laser cooling. They propose a laser-electron storage ring (LESR) where the electron beam in a compact storage ring repetitively interacts with an intense laser pulse stored in an optical resonator. The laser-electron interaction gives rise to fast cooling of electron beams and can be used to overcome the space-charge effects encountered in a medium-energy circular machine. Applications to the designs of ultra-low-emittance damping rings and compact x-ray sources are also explored.

  10. High-brightness electron beam diagnostics at the ATF

    SciTech Connect

    Wang, X.J.; Ben-Zvi, I.

    1996-07-01

    The Brookhaven Accelerator Test Facility (ATF) is a dedicated user facility for accelerator physicists. Its design is optimized to explore laser acceleration and coherent radiation production. To characterize the low-emittance, picoseconds long electron beam produced by the ATF`s photocathode RF gun, we have installed electron beam profile monitors for transverse emittance measurement, and developed a new technique to measure electron beam pulse length by chirping the electron beam energy. We have also developed a new technique to measure the ps slice emittance of a 10 ps long electron beam. Stripline beam position monitors were installed along the beam to monitor the electron beam position and intensity. A stripline beam position monitor was also used to monitor the timing jitter between the RF system and laser pulses. Transition radiation was used to measure electron beam energy, beam profile and electron beam bunch length.

  11. Ion acceleration mechanism in electron beams

    SciTech Connect

    Popov, A.F.

    1982-07-01

    Analysis of experimental data reveals that several processes observed in diodes and during the transport of intense electron beams in a neutral gas result from polarization of a plasma in an electric field. Under certain conditions this effect gives rise to a high-field region at the boundary of a plasma column. The electron beam is strongly focused in this region. As a result, a two-dimensional potential well forms at the crossover point of a strongly focused beam. The electric field at this well can reach several megavolts per centimeter. The crossover point moves as a result of expansion of the plasma cloud. The ions trapped in the potential well are accelerated. There is effective acceleration over a distance of the order of a few times the beam radius. A new physical model gives a satisfactory explanation of the experimental results.

  12. Beam Charge Asymmetry Monitors for Low Intensity Continuous Electron Beam

    SciTech Connect

    Jean-Claude Denard; Arne P. Freyberger; Youri Sharabian

    2001-05-01

    Experimental Hall B at Jefferson Lab typically operates with CW electron beam currents in the range of 1 - 10 nA. This low beam current coupled with a 30 Hz flip rate of the beam helicity required the development of new devices to measure and monitor the beam charge asymmetry. We have developed four independent devices with sufficient bandwidth for readout at 30 Hz rate: a synchrotron light monitor (SLM), two backward optical transition radiation monitors (OTR) and a Faraday Cup. Photomultipliers operating in current mode provided the readout of the light from the SLM and the OTRs, while high bandwidth electronics provided the readout from the Faraday cup. Using {approximately}6 helicity pairs, we measured the beam charge asymmetry to a statistically accuracy which is better than 0.05%. We present the results from the successful operation of these devices during the fall 2000 physics program. The reliability and the bandwidth of the devices allowed us to control the gain on the source laser by means of a feedback loop.

  13. Medulloblastoma therapy using electron beams

    SciTech Connect

    Vijayakumar, S.; Muller-Runkel, R.

    1985-11-01

    The use of megavoltage photons for the spinal component of cerebrospinal axis irradiation is responsible for most of the long-term sequelae in children with medulloblastomas who undergo this procedure. The technique and advantages of using electrons for this component of the procedure are described.

  14. 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.

  15. 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.

  16. Electron beam induced growth of tin whiskers

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  17. Prototype electron lens set-up for the Tevatron beam-beam compensation

    SciTech Connect

    Crawford, C.; Saewert, G.; Santucci, J.; Sery, A.; Shemyakin, A.; Shiltsev, V.; Wildman, D.; Aleksandrov, A.; Arapov, L.; Kuznetsov, G.; Logachov, P.; Sharapa, A.; Skarbo, B.; Sukhina, B.

    1999-05-17

    A prototype "electron lens" for the Tevatron beam-beam compensation project is commissioned at Fermilab. We de-scribe the set-up, report results of the first tests of the elec-tron beam, and discuss future plans.

  18. Electron beams in research and technology

    NASA Astrophysics Data System (ADS)

    Mehnert, R.

    1995-11-01

    Fast electrons lose their energy by inelastic collisions with electrons of target molecules forming secondary electrons and excited molecules. Coulomb interaction of secondary electrons with valence electrons of neighboring molecules leads to the formation of radical cations, thermalized electrons, excited molecular states and radicals. The primary reactive species initiate chemical reactions in the materials irradiated. Polymer modifications using accelerated electrons such as cross-linking of cable insulation, tubes, pipes and moldings, vulcanization of elastomers, grafting of polymer surfaces, processing of foamed plastics and heat shrinkable materials have gained wide industrial acceptance. A steadily growing electron beam technology is curing of paints, lacquers, printing inks and functional coatings. Electron beam processing offers high productivity, the possibility to treat the materials at normal temperature and pressure, excellent process control and clean production conditions. On an industrial scale the most important application of fast electrons is curing of 100% reactive monomer/prepolymer systems. Mainly acrylates and epoxides are used to formulate functional coatings on substrates such as paper, foil, wood, fibre board and high pressure laminates. A survey is given about the reaction mechanism of curing, the characterization of cured coatings, and of some industrial application.

  19. REBL nanowriter: Reflective Electron Beam Lithography

    NASA Astrophysics Data System (ADS)

    Petric, Paul; Bevis, Chris; Brodie, Alan; Carroll, Allen; Cheung, Anthony; Grella, Luca; McCord, Mark; Percy, Henry; Standiford, Keith; Zywno, Marek

    2009-03-01

    REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam direct write maskless lithography. The system is specifically targeting 5 to 7 wafer levels per hour throughput on average at the 45 nm node, with extendibility to the 32 nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the Digital Pattern Generator (DPG). The DPG is a CMOS ASIC chip with an array of small, independently controllable cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The exposure method utilized by the DPG was emulated on a Vistec VB-6 in order to validate the gray level exposure method used in REBL. Results of these exposure tests are discussed.

  20. Effect of Backscattered Electrons on Electron Beam Focus

    SciTech Connect

    Falabella, S; Chen, Y-J; Houck, T; McCarrick, J; Sampayan, S; Weir, J

    2000-08-10

    Using an induction linac, ETA-II, we are studying the interaction of a 2 kA, 6 MeV electron beam focused to a <2 mm diameter spot on high-Z foils. A focus shift was noticed when changing from 5 mil to 40 mil tantalum foil targets. This shift was subsequently attributed to the effect of a substantial fraction of the incident electron beam backscattering from the target, reducing the net beam current. This fraction varies with the thickness and density of the target. The presence and magnitude of the backscattered component was confirmed using Faraday cup collectors and beam current monitors. Calculations confirm the magnitude of the focus shift is consistent with the observed backscattered fraction.

  1. Proposed LLNL electron beam ion trap

    SciTech Connect

    Marrs, R.E.; Egan, P.O.; Proctor, I.; Levine, M.A.; Hansen, L.; Kajiyama, Y.; Wolgast, R.

    1985-07-02

    The interaction of energetic electrons with highly charged ions is of great importance to several research fields such as astrophysics, laser fusion and magnetic fusion. In spite of this importance there are almost no measurements of electron interaction cross sections for ions more than a few times ionized. To address this problem an electron beam ion trap (EBIT) is being developed at LLNL. The device is essentially an EBIS except that it is not intended as a source of extracted ions. Instead the (variable energy) electron beam interacting with the confined ions will be used to obtain measurements of ionization cross sections, dielectronic recombination cross sections, radiative recombination cross sections, energy levels and oscillator strengths. Charge-exchange recombinaion cross sections with neutral gasses could also be measured. The goal is to produce and study elements in many different charge states up to He-like xenon and Ne-like uranium. 5 refs., 2 figs.

  2. 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.

  3. Electron beam experiments at high altitudes

    NASA Technical Reports Server (NTRS)

    Olsen, R. C.

    1987-01-01

    Experiments with the electron gun on the SCATHA satellite produced evidence of beam-plasma interactions, and heating of the low energy electrons around the satellite. These experiments were conducted near geosynchronous orbit, in the dusk bulge, and plasma sheet, with one short operation in the lobe regions, providing a range of ambient plasma densities. The electron gun was operated at 50 eV, with beam currents of 1, 10, and 100 micro-A. Data from electrostatic analyzers and the dc electric field experiment show that the satellite charged to near the beam energy in sunlight, if the beam current was sufficient. Higher ambient densities required higher beam currents. The electrostatic analyzers showed distribution functions which had peaks, or plateaus, at energies greater than the satellite potential. These measurements indicate heating of the ambient plasma at several Debye lengths from the satellite, with the heated plasma then accelerated into the satellite. It is likely that the ambient plasma is in fact the photoelectron sheath generated by the satellite.

  4. Electron beam experiments at high altitudes

    NASA Technical Reports Server (NTRS)

    Olsen, R. C.; Cohen, H. A.

    1988-01-01

    Experiments with the electron gun on the SCATHA satellite produced evidence of beam-plasma interactions, and heating of the low energy electrons around the satellite. These experiments were conducted near geosynchronous orbit, in the dusk bulge, and plasma sheet, with one short operation in the lobe regions, providing a range of ambient plasma densities. The electron gun was operated at 50 eV, with beam currents of 1, 10, and 100 micro-A. Data from electrostatic analyzers and the DC electric field experiment show that the satellite charged to near the beam energy in sunlight, if the beam current was sufficient. Higher ambient densities required higher beam currents. The electrostatic analyzers showed distribution functions which had peaks, or plateaus, at energies greater than the satellite potential. These measurements indicate heating of the ambient plasma at several Debye lengths from the satellite, with the heated plasma then accelerated into the satellite. It is likely that the ambient plasma is in fact the photoelectron sheath generated by the satellite.

  5. 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.

  6. 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.

  7. Helical relativistic electron beam Vlasov equilibria

    NASA Astrophysics Data System (ADS)

    Lai, H. M.

    1980-08-01

    Three existing helical relativistic electron beam models are discussed and compared. Both Yoshikawa's and Lawson's models are shown to be derivable from appropriate Vlasov equilibria. A new helical Vlasov equilibrium with energy spread is presented and studied. Unlike Auer's axial current model in which the allowance of an energy spread limits the total current in the relativistic beam case, the present model, with the addition of an azimuthal current, permits solutions with arbitrarily large current. On the other hand, like the model studied by Kan and Lai, the present model leads to nonhollowed-out beam solutions in which, the larger the beam current, the more force-free is the magnetic field configuration.

  8. 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

  9. 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.

  10. Toward a cold electron beam in the Fermilab's Electron Cooler

    SciTech Connect

    Vitali S. Tupikov et al.

    2004-05-12

    Fermilab is developing a high-energy electron cooling system to cool 8.9-GeV/c antiprotons in the Recycler ring [1]. Cooling of antiprotons requires a round electron beam with a small angular spread propagating through 20-m long cooling section with a kinetic energy of 4.3 MeV. To confine the electron beam tightly and to keep its transverse angles below 0.1 mrad, the cooling section will be immersed into a solenoidal field of 50-150G. This paper describes the technique of measuring and adjusting the magnetic field quality in the cooling section and presents preliminary results of beam quality measurements in the cooler prototype.

  11. 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.

  12. 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.

  13. Electron beam puts a shine on leather

    SciTech Connect

    Berberich, S.

    1986-02-01

    A technique for curing leather using either ultraviolet or electron-beam radiation has been developed. This type of radiation curing saves at least 60 percent of the energy cost of conventional leather finishing and can also result in considerable savings in plant space and labor. The implications of the new technology in international balance of trade are discussed.

  14. Free electron laser for a mildly relativistic electron beam

    SciTech Connect

    Uhm, H.S.

    1983-08-01

    One of the most basic instabilities which characterize a relativistic electron beam propagating through a helical wiggler (or undulator) magnetic field is the free electron laser instability. This instability has been extensively investigated in recent years with particular emphasis on applications involving high power microwave radiation. Previous theoretical studies of this instability have tended to result in the conclusion that high energy beams with a relativistic factor much greater than 1 are required to generate high frequency microwave radiation. Beams with this high a relativistic factor have proven to be highly unsuited, however, to compact and practical microwave tubes. To this end, for a relativistic electron beam propagating through a dielectric loaded waveguide, this paper presents a method for the bandwidth and frequency enhancement of the free electron laser instability which makes use of a mild (less than 1.5) relativistic factor. It demonstrates that the instability bandwidth and frequency can be greatly enhanced for specified values of the beam energy and wiggler wavelength if the dielectric constant and the thickness of the dielectric material are appropriately selected. The paper also presents a new scheme for a broad bandwidth microwave amplifier.

  15. Electron beam induced conductivity effect of polymer resists and charging induced electron beam deflection simulation in electron beam lithography

    NASA Astrophysics Data System (ADS)

    Hwu, Justin Jia-Jen

    2000-10-01

    The electron beam induced conductivity (EBIC) effect of polymer materials was investigated and three electron beam resists, PBS, EBR900, and ZEP7000, were used as target materials in this research. An external bias method was applied for the direct measurements of EBIC current and the EBIC conductivity was then derived. The temperature effect on EBIC was illustrated by EBR900 and a simple single trap level analysis gave good agreement in explanation of initial state conductivity dependence on temperature change. The dependence of initial state EBIC values on dose rates and bias was also determined and an empirical from of EBIC-bias relationship was established for the electron beam deflection modeling. The long term EBIC characteristics of resists were investigated under different dose rates. The variation of EBIC versus time was explained by a transient theory that considers rates of carrier generation, carrier trapping, carrier detrapping, and carrier recombination contribution. The trapping model analysis on steady state EBIC results revealed that PBS has a uniform distribution of traps, while EBR900 and ZEP7000 fall in the same category that has exponential distribution of traps. The steady state EBIC gain was also determined for the three resists and the onset of the plasma region was observed for EBR900 and ZEP7000. A simulation model for the calculation of electron beam deflection owing to resist charging was developed in the second part of this research. Charging patterns of circles and squares of different dimensions were considered. Both SIMION and MATHEMATICA were used as simulation tools and the limitation of SIMION was illustrated and discussed. The model programmed in MATHEMATICA simulated electron beam deflection during e-beam writing. With the combination of the empirical EBIC-bias relationship of EBR900, the model simulated surface potential decay after irradiation and the results showed good agreement with literature values. The extent of

  16. An electron beam detector for the FLASH II beam dump

    NASA Astrophysics Data System (ADS)

    Good, J.; Kube, G.; Leuschner, N.; Perlick, F.; Sachwitz, M.; Schmitz, M.; Wittenburg, K.; Wohlenberg, T.

    2013-05-01

    After the generation of the laser light, a dipole deflects the highly energetic electron beam of FLASH (Free Electron Laser Hamburg) into a dump. A detector is developed to monitor the position, dimensions and profile of the electron beam. Scintillation light is emitted due to the electrons hitting a luminescent screen located in front of the dump aperture. This light is guided by an optical system external to the vacuum to a CCD camera for optical analysis of the generated image. In this paper the layouts of two different optical systems are presented, both of which will be redundantly installed at FLASH II. The conventional lens-mirror-arrangement, consisting of three single collecting lenses, two mirrors and a zoom lens, is supposed to have a theoretical resolution of 0.25 mm. The second optical system is based on radiation-hard optical fibres. For the latter it is planned to test the impact of radiation on the optical qualities of the bundle by installing it into a "radioactive hot spot" at the bunch compressor in the FLASH accelerator. This test setup will also be presented.

  17. High-throughput electron-beam lithography

    NASA Astrophysics Data System (ADS)

    Feinerman, Alan D.; Crewe, David A.; Perng, Dung-Ching; Shoaf, S. E.; Crewe, Albert V.

    1992-08-01

    A new approach for fabricating arrays of electron beam columns by stacking silicon wafers with micron accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create an array of apertures on the top or bottom of the wafer and four orthogonal v- grooves on both surfaces of the wafer. Precision pyrex fibers align and bond the v-grooves on the top of one wafer to the bottom of the next wafer. This procedure is repeated to create thick structures and a stack of six wafers is used to create arrays of scanning electron microscopes (SEMs). This technique is suitable for fabricating 1 - 30 mm long electron optical columns. The optimum size is determined by the desired array size, operating voltage, resolution, field of view, and working distance. The first wafer contains an array of micromachined field emission electron sources. The next three wafers accelerate and focus the electron beams. The last two wafers in the stack have electrodes to deflect each beam and correct for astigmatism. The performance of an SEM improves as its length is reduced and a subcm 2 keV SEM with a field emission source should have approximately 7 nm resolution.

  18. Electron beam driven disordering in small particles

    SciTech Connect

    Vanfleet, R.R.; Mochel, J.

    1997-11-01

    Small metal particles in the range of a few nanometers in diameter are seen to progressively disorder when the 100 keV electron beam of a Scanning Transmission Electron Microscope (STEM) is held stationary on the particle. The diffraction pattern of the individual particle is seen to progress from an initial array of indexable diffraction spots to a mixture of diffraction spots and amorphous-like rings and finally to rings with no persistent diffraction spots. After the electron beam is removed, the particles will recrystallize after minutes or hours. Only particles below a critical size are seen to fully disorder. The authors have observed this in platinum, palladium, rhodium, and iridium and based on the model of disordering process believe it is a universal effect. It has also been observed with a platinum ruthenium alloy. They discuss the mechanism of this disordering and the structure of the resulting disordering particle for the case of platinum clusters.

  19. Electron beam facility for divertor target experiments

    SciTech Connect

    Anisimov, A.; Gagen-Torn, V.; Giniyatulin, R.N.

    1994-12-31

    To test different concepts of divertor targets and bumpers an electron beam facility was assembled in Efremov Institute. It consists of a vacuum chamber (3m{sup 3}), vacuum pump, electron beam gun, manipulator to place and remove the samples, water loop and liquid metal loop. The following diagnostics of mock-ups is stipulated: (1) temperature distribution on the mock-up working surface (scanning pyrometer and infra-red imager); (2) temperature distribution over mocked-up thickness in 3 typical cross-sections (thermo-couples); (3) cracking dynamics during thermal cycling (acoustic-emission method), (4) defects in the mock-up before and after tests (ultra-sonic diagnostics, electron and optical microscopes). Carbon-based and beryllium mock-ups are made for experimental feasibility study of water and liquid-metal-cooled divertor/bumper concepts.

  20. 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)

  1. Fundamentals of high energy electron beam generation

    NASA Astrophysics Data System (ADS)

    Turman, B. N.; Mazarakis, M. G.; Neau, E. L.

    High energy electron beam accelerator technology has been developed over the past three decades in response to military and energy-related requirements for weapons simulators, directed-energy weapons, and inertially-confined fusion. These applications required high instantaneous power, large beam energy, high accelerated particle energy, and high current. These accelerators are generally referred to as 'pulsed power' devices, and are typified by accelerating potential of millions of volts (MV), beam current in thousands of amperes (KA), pulse duration of tens to hundreds of nanoseconds, kilojoules of beam energy, and instantaneous power of gigawatts to teffawatts (10(exp 9) to 10(exp 12) watts). Much of the early development work was directed toward single pulse machines, but recent work has extended these pulsed power devices to continuously repetitive applications. These relativistic beams penetrate deeply into materials, with stopping range on the order of a centimeter. Such high instantaneous power deposited in depth offers possibilities for new material fabrication and processing capabilities that can only now be explored. Fundamental techniques of pulse compression, high voltage requirements, beam generation and transport under space-charge-dominated conditions will be discussed in this paper.

  2. 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.

  3. 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.

  4. Electron beam recording of optical disc

    NASA Astrophysics Data System (ADS)

    Cartwright, Giles; Reynolds, Gerald; Baylis, Chris; Pearce, Adrian; Dix, Colin; Ogilvie, Nick

    2002-09-01

    The Nimbus Technology & Engineering e -Beam Mastering System was developed to gain a large improvement in optical disc and structured hard disc recording capacity, significantly more than is possible from deep UV and SIL mastering. The current electron beam recorder is essentially a production machine capable of making full-length exposures at capacities of up to 50 GB with a simple low-cost upgrade path to disc capacities of several hundred gigabytes and beyond and hard disk drives (HDD) with capacities of up to 1 tera bit per square inch.

  5. Installation of electric field electron beam blanker in high-resolution transmission electron microscopy

    SciTech Connect

    Hayashida, Misa; Kimura, Yoshihide; Taniguchi, Yoshifumi; Otsuka, Masayuki; Takai, Yoshizo

    2006-11-15

    We have newly installed an electric field electron beam blanker in a transmission electron microscopy, which chops an electron beam very quickly without the effect of hysteresis. The electric field, which is generated by the electron beam blanker, deflects the electron beam, and the electron beam is intercepted by an aperture. The response time of the beam blanker is 50 {mu}s. Therefore, a very short pulsed electron beam enables a charge-coupled device camera to directly expose an electron beam spot or diffraction pattern. Moreover, we measured the response of a deflector coil, which is usually used as an electron beam blanker, using our electron beam blanker. Our beam blanker will become a key component in a computer-assisted minimal dose system, which enables us to reduce the electron dose of the sample.

  6. 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

  7. 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.

  8. SPALLATION NEUTRON SOURCE BEAM CURRENT MONITOR ELECTRONICS.

    SciTech Connect

    KESSELMAN,M.; DAWSON,W.C.

    2002-05-06

    This paper will discuss the present electronics design for the beam current monitor system to be used throughout the Spallation Neutron Source (SNS) under construction at Oak Ridge National Laboratory. The beam is composed of a micro-pulse structure due to the 402.5MHz RF, and is chopped into mini-pulses of 645ns duration with a 300ns gap, providing a macro-pulse of 1060 mini-pulses repeating at a 60Hz rate. Ring beam current will vary from about 15ma peak during studies, to about 50Amps peak (design to 100 amps). A digital approach to droop compensation has been implemented and initial test results presented.

  9. 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.

  10. Progress with Tevatron Electron Lens Head-On Beam-Beam Compensation

    SciTech Connect

    Valishev, A.; Kuznetsov, G.; Shiltsev, V.; Stancari, G.; Zhang, X.

    2010-05-19

    Tevatron electron lenses have been successfully used to mitigate bunch-to-bunch differences caused by longrange beam-beam interactions. For this purpose, the electron beam with uniform transverse density distribution was used. Another planned application of the electron lens is the suppression of tune spread due to head-on beam-beam collisions. For this purpose, the transverse distribution of the E{sup -} beam must be matched to that of the antiproton beam. In 2009, the Gaussian profile electron gun was installed in one of the Tevatron electron lenses. We report on the first experiments with non-linear beam-beam compensation. Discussed topics include measurement and control of the betatron tune spread, importance of the beam alignment and stability, and effect of electron lens on the antiproton beam lifetime.

  11. ELECTRON BEAM THERAPY OF MYCOSIS FUNGOIDES

    PubMed Central

    Bagshaw, Malcolm A.; Schneidman, Harold M.; Farber, Eugene M.; Kaplan, Henry S.

    1961-01-01

    Ionizing radiation in the form of x-ray therapy is the best modality of treatment available at the present time for single, isolated lesions of mycosis fungoides. However, for generalized mycosis fungoides, generalized x-ray therapy is technically difficult and dangerous. It is now possible to employ electron beam therapy for generalized mycosis fungoides, using energies which confine the dose to the superficial layers of the skin and thus avoid hematopoietic injury. A technique for wide field electron beam therapy has been developed for this purpose which has been effective and well tolerated in limited trials to date. ImagesFigure 2.Figure 4.Figure 4.Figure 4.Figure 5.Figure 5.Figure 5.Figure 6. AFigure 6. A PMID:13863947

  12. 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.

  13. Multiple Electron Stripping of Heavy Ion Beams

    SciTech Connect

    D. Mueller; L. Grisham; I. Kaganovich; R. L. Watson; V. Horvat; K. E. Zaharakis; Y. Peng

    2002-06-25

    One approach being explored as a route to practical fusion energy uses heavy ion beams focused on an indirect drive target. Such beams will lose electrons while passing through background gas in the target chamber, and therefore it is necessary to assess the rate at which the charge state of the incident beam evolves on the way to the target. Accelerators designed primarily for nuclear physics or high energy physics experiments utilize ion sources that generate highly stripped ions in order to achieve high energies economically. As a result, accelerators capable of producing heavy ion beams of 10 to 40 Mev/amu with charge state 1 currently do not exist. Hence, the stripping cross-sections used to model the performance of heavy ion fusion driver beams have, up to now, been based upon theoretical calculations. We have investigated experimentally the stripping of 3.4 Mev/amu Kr 7+ and Xe +11 in N2; 10.2 MeV/amu Ar +6 in He, N2, Ar and Xe; 19 MeV/amu Ar +8 in He, N2, Ar and Xe; 30 MeV He 1 + in He, N2, Ar and Xe; and 38 MeV/amu N +6 in He, N2, Ar and Xe. The results of these measurements are compared with the theoretical calculations to assess their applicability over a wide range of parameters.

  14. Production of slow-positron beams with an electron linac

    SciTech Connect

    Howell, R.H.; Alvarez, R.A.; Stanek, M.

    1982-03-26

    Intense, pulsed beams of low-energy positrons have been produced by a high-energy beam from an electron linac. The production efficiency for low-energy positrons has been determined for electrons with 60 to 120 MeV energy, low-energy positron beams from a linac can be of much higher intensity than those beams currently derived from radioactive sources.

  15. Preventing Contamination In Electron-Beam Welds

    NASA Technical Reports Server (NTRS)

    Goodin, Wesley D.; Gulbrandsen, Kevin A.; Oleksiak, Carl

    1990-01-01

    Simple expedient eliminates time-consuming, expensive manual hand grinding. Use of groove and backup tube greatly reduces postweld cleanup in some electron-beam welding operations. Tube-backup method developed for titanium parts, configurations of which prevents use of solid-block backup. In new welding configuration, tube inserted in groove to prevent contact between alumina beads and molten weld root. When welding complete and beads and tube removed, only minor spatter remains and is ground away easily.

  16. Further remarks on electron beam pumping of laser materials.

    PubMed

    Klein, C A

    1966-12-01

    This article demonstrates that recently completed studies on the energy dissipation of kilovolt electron beams in solids provide readily applicable methods for assessing the situation in electron beam pumped lasers. PMID:20057662

  17. System of video observation for electron beam welding process

    NASA Astrophysics Data System (ADS)

    Laptenok, V. D.; Seregin, Y. N.; Bocharov, A. N.; Murygin, A. V.; Tynchenko, V. S.

    2016-04-01

    Equipment of video observation system for electron beam welding process was developed. Construction of video observation system allows to reduce negative effects on video camera during the process of electron beam welding and get qualitative images of this process.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Experimental studies of compensation of beam beam effects with Tevatron electron lenses

    NASA Astrophysics Data System (ADS)

    Shiltsev, V.; Alexahin, Y.; Bishofberger, K.; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.

    2008-04-01

    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 paper, 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.

  4. Coherent Radiation from Relativistic Electron Beams.

    NASA Astrophysics Data System (ADS)

    Chen, Kuan-Ren

    Two new laser concepts, the Ion-Ripple Laser (IRL) and the Ion-Channel Laser (ICL), are proposed. A unified theory for coherent radiation from relativistic electron beams devices is developed; the theory not only links the physics of Cyclotron Masers (CMs) and Free Electron Lasers (FELs) but covers the physics of the IRLs and the ICLs. We have also invented a new numerical method, the Neo-Finite -Difference (NFD) method, for electromagnetic plasma simulations and applied it to studies of these lasers. The unified amplification theory compares the growth mechanisms. Two bunching mechanisms (both axial and azimuthal) exist, not only for the noncollective single electron resonance regime, but also in the collective gain regime. Competition or reinforcement between the two bunching mechanisms is determined by the q value (a parameter that determines how the electron oscillation frequency depends on energy), the electron axial velocity, and the wave phase velocity. The unified theory concludes that, for wave amplification, the sign of the electron mismatch frequency is required to be the same as the sign of a bunching parameter that is determined by the total bunching. In an IRL, a relativistic electron beam propagates obliquely through an ion ripple in a plasma. The radiation frequency depends on the beam energy, the ripple wave number, and the angle: omega ~ 2gamma ^{2}k_{ir}ccos theta. By proper choice of device parameters, sources of microwaves, optical, and perhaps even X-rays can be made. The dispersion relation for wave coupling is derived and used to calculate the radiation frequency and linear growth rate. The nonlinear saturation mechanism is explored. Computer simulation is used to verify the ideas, scaling laws and nonlinear mechanisms. In an ICL, the ion focusing force causes the electrons to oscillate about the channel axis and plays a similar role to the magnetic field in a CM. This electron motion is nonlinear and is studied. Simulations were performed

  5. 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.

  6. 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.

  7. 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.

  8. Experimental demonstration of colliding beam lifetime improvement by electron lenses

    SciTech Connect

    Shiltsev, Vladimir; Alexahin, Yuri; Kamerdzhiev, Vsevolod; Kuznetsov, Gennady; Zhang, Xiao-Long; Bishofberger, Kip; /Los Alamos

    2007-10-01

    We report successful application of space-charge forces of a low-energy electron beam for improvement of particle lifetime determined by beam-beam interaction in high-energy collider. In our experiments, an electron lens, a novel instrument developed for the beam-beam compensation, was set on a 980-GeV proton bunch in the Tevatron proton-antiproton collider. The proton bunch losses due to its interaction with antiproton beam were reduced by a factor of 2 when the electron lens was operating. We describe the principle of electron lens operation and present experimental results.

  9. Development of ferroelectric electron beam diodes

    SciTech Connect

    Flechtner, D.; Ivers, J.D.; Kerslick, G.A.; Nation, J.A.; Schaechter, L.; Zhang, G.

    1995-12-31

    The authors are currently investigating the use of ferroelectric ceramics for electron beam generation. These materials exhibit a spontaneous (saturation) polarization, P{sub s}, of up to 100{mu}C/cm{sup 2}. Emission occurs when the polarization state of the ferroelectric is changed rapidly by an applied electric field, and a fraction of the surface screening charge is released at a gridded electrode. Using a Lead-Zirconate-Titanate (PZT) ceramic as the electron source in a planar 14kV diode geometry they have measured diode current densities of up to 40A/cm{sup 2} with a 5cm gap. The normalized rms emittance of this beam has been measured to be 12{pi} mm-mrad at 8A. Recent results from experiments to extend operation of this diode up to 70 kV, 300 ns pulses will be reported. They are also designing a 20--30 kV, 1 {micro}s system that will be operated in a repetition rate mode. They are planning to use such a system as part of their program to develop compact X-band sources with average power levels in the hundreds of watts range. Using simulation codes, such as EGUN, together with results from analytical work TWT structures are being designed for use with these sources. The advantages of using PPM focusing in both cylindrical or sheet beam configurations are also under investigation.

  10. Ionospheric modification using relativistic electron beams

    NASA Technical Reports Server (NTRS)

    Banks, Peter M.; Fraser-Smith, Anthony C.; Gilchrist, B. E.

    1990-01-01

    The recent development of comparatively small electron linear accelerators (linacs) now makes possible a new class of ionospheric modification experiments using beams of relativistic electrons. These experiments can potentially provide much new information about the interactions of natural relativistic electrons with other particles in the upper atmosphere, and it may also make possible new forms of ionization structures extending down from the lower ionosphere into the largely un-ionized upper atmosphere. The consequences of firing a pulsed 1 A, 5 Mev electron beam downwards into the upper atmosphere are investigated. If a small pitch angle with respect to the ambient geomagnetic field is selected, the beam produces a narrow column of substantial ionization extending down from the source altitude to altitudes of approximately 40 to 45 km. This column is immediately polarized by the natural middle atmosphere fair weather electric field and an increasingly large potential difference is established between the column and the surrounding atmosphere. In the regions between 40 to 60 km, this potential can amount to many tens of kilovolts and the associated electric field can be greater than the field required for breakdown and discharge. Under these conditions, it may be possible to initiate lightning discharges along the initial ionization channel. Filamentation may also occur at the lower end to drive further currents in the partially ionized gases of the stratosphere. Such discharges would derive their energy from the earth-ionosphere electrical system and would be sustained until plasma depletion and/or electric field reduction brought the discharge under control. It is likely that this artificially-triggered lightning would produce measurable low-frequency radiation.

  11. Bunch length effects in the beam-beam compensation with an electron lens

    SciTech Connect

    Fischer, W.; Luo, Y.; Montag, C.

    2010-02-25

    Electron lenses for the head-on beam-beam compensation are under construction at the Relativistic Heavy Ion Collider. The bunch length is of the same order as the {beta}-function at the interaction point, and a proton passing through another proton bunch experiences a substantial phase shift which modifies the beam-beam interaction. We review the effect of the bunch length in the single pass beam-beam interaction, apply the same analysis to a proton passing through a long electron lens, and study the single pass beam-beam compensation with long bunches. We also discuss the beam-beam compensation of the electron beam in an electron-ion collider ring.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Inspection applications with higher electron beam energies

    NASA Astrophysics Data System (ADS)

    Norman, D. R.; Jones, J. L.; Yoon, W. Y.; Haskell, K. J.; Sterbentz, J. W.; Zabriskie, J. M.; Hunt, A. W.; Harmon, F.; Kinlaw, M. T.

    2005-12-01

    The Idaho National Laboratory has developed prototype shielded nuclear material detection systems based on pulsed photonuclear assessment (PPA) techniques for the inspection of cargo containers. During this work, increased nuclear material detection capabilities have been demonstrated at higher electron beam energies than those allowed by federal regulations for cargo inspection. This paper gives a general overview of a nuclear material detection system, the PPA technique and discusses the benefits of using these higher energies. This paper also includes a summary of the numerical and test results from LINAC operations up to 24 MeV and discusses some of the federal energy limitations associated with cargo inspection.

  3. 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.

  4. Electron beam pumping of CdZnSe quantum well laser structures using a variable energy electron beam

    NASA Astrophysics Data System (ADS)

    Trager-Cowan, C.; Bagnall, D. M.; McGow, F.; McCallum, W.; O'Donnell, K. P.; Smith, P. C.; Wright, P. J.; Cockayne, B.; Prior, K. A.; Mullins, J. T.; Horsburgh, G.; Cavenett, B. C.

    1996-02-01

    In this paper we present experimental results on electron beam pumping of MBE and MOVPE lasers with CdZnSe single quantum wells. Laser emission in the gree and blue occurs under pulsed excitation, with threshold power densities typically less than 2 kW/cm 2 at low temperatures. Threshold curves obtained at different electron beam energies show that there is an optimum electron beam energy for wells at a given depth below the surface. This suggests that it is possible to match the electron beam energy to a given structure. Results are broadly consistent with Monte Carlo calculations of the depth dependence of the energy deposition of the electron beam.

  5. 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.

  6. 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

  7. 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. PMID:27620188

  8. Study on nanosecond pulsed electron beam generation

    NASA Astrophysics Data System (ADS)

    Ponomarev, D.; Kholodnaya, G.; Remnev, G.; Kaikanov, M.; Sazonov, R.

    2014-11-01

    The paper presents the findings of an investigation on volt-ampere characteristics of the diode with explosive emission cathodes of different constructions (blade metal-dielectric (MD-cathode) and solid graphite cathodes) under the change of the anode-cathode gap in wide ranges. The investigations were carried out using the TEA-500 pulsed electron accelerator. The total current of the electron beam was measured using the Faraday cup (FC). A 0.5-mm foiled glass fiber laminate was used as an emitting edge of the cathode in the experimental study with the explosive emission blade MD-cathode. Based on the obtained results, the conclusion was made that the graphite cathode has the most effective efficiency factor.

  9. 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.

  10. 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. PMID:27203186

  11. 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.

  12. Electron beam EUV patterned mask inspection system

    NASA Astrophysics Data System (ADS)

    Yamada, Keizo; Kitayama, Yasunobu; Fiekowsky, Peter

    2011-11-01

    EUV lithography is expected to begin production in 2014. Production of successful EUV photomasks requires patterned mask inspection (PMI). The ultimate PMI tool is expected to utilize actinic (EUV) illumination. Development of such a tool is expected to require three years after funding. Current test EUV masks, such as 22 nm, can be inspected using 193 nm wavelength deep UV (DUV) inspection tools similar to those currently being used for DUV masks. The DUV inspection tools may be extended for the 16 nm node. However EUV production is expected to start with 11 nm node masks which cannot be inspected with proposed DUV inspection tools. Therefore E-beam inspection (EBI) is discussed as the interim PMI method. EBI has the advantage of high resolution and the disadvantages of low inspection speed and relative insensitivity to ML defects (in the multi-layer material). EBI inspection speed is limited by the pixel size, pixel capture rate and the number of electron columns. The pixel rate is limited by the detector time-resolution, the beam current, and the detection efficiency. Technical improvements in beam focus, secondary electron detection, and defect detection and analysis provide good performance for 22 nm node masks. We discuss the advances and show that performance can be extrapolated for 16 and 11 nm node patterned mask inspections. We present sensitivity and false-defect frequency results of using the Holon EBI tool on 22 nm test masks and a roadmap for extending its operation for use on 16 and 11 nm node masks for inspections requiring 2-5 hours per mask.

  13. High power, electron-beam induced switching in diamond

    SciTech Connect

    Scarpetti, R.D.; Hofer, W.W.; Kania, D.R.; Schoenbach, K.H.; Joshi, R.P.; Molina, C.; Brinkmann, R.P.

    1993-07-01

    We are developing a high voltage, high average power, electron-beam controlled diamond switch that could significantly impact high power solid-state electronics in industrial and defense applications. An electron-beam controlled thin-film diamond could switch well over 100 kW average power at MHz frequencies, greater than 5 kV, and with high efficiency. This performance is due to the excellent thermal and electronic properties of diamond, the high efficiency achieved with electron beam control, and the demonstrated effectiveness of microchannel cooling. Our electron beam penetration depth measurements agree with our Monte-Carlo calculations. We have not observed electron beam damage in diamond for beam energies up to 150 keV. In this paper we describe our experimental and calculational results and research objectives.

  14. Extraction of a steady state electron beam from HCD (hollow cathode discharge) plasmas for EBIS (electron beam ion source) applications

    SciTech Connect

    Hershcovitch, A.; Kovarik, V.; Prelec, K.

    1988-01-01

    Experiments to extract high brightness electron beams from hollow cathode discharge plasmas are now in progress. A unique feature of these plasmas, which in principle can facilitate the extraction of large current low emittance electron beams, is the existence of a relatively high energy electron population with a very narrow energy spread. This electron population was identified in a self-extraction experiment, which yielded a 35 eV, 600 mA electron beam with parallel energy spread of less than 0.5 eV. Preliminary, crude application of 2.5 kV extraction voltage yielded a steady state electron beam current of 1.2 A. The end result of this endeavor would be an Electron Beam Ion Source (EBIS) with an electron beam current of 6 A. 4 refs., 2 figs.

  15. 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.

  16. 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.

  17. Polymeric flocculants processing by accelerated electron beams and microwave heating

    NASA Astrophysics Data System (ADS)

    Martin, Diana I.; Mateescu, Elena; Craciun, Gabriela; Ighigeanu, Daniel; Ighigeanu, Adelina

    2002-08-01

    Results obtained by accelerated electron beam, microwave and simultaneous microwave and electron beam application in the chemistry of acrylamide and acrylic acid copolymers (polymeric flocculants used for wastewater treatment) are presented. Comparative results concerning the molecular weight and Huggins' constant for the acrylamide and acrylic acid copolymers obtained by classical heating, microwave heating, electron beam irradiation and simultaneous microwave and electron beam treatment are reported. Microwave heating produces high water solubility of the polymeric flocculants but median molecular weight values. Electron beam irradiation gives high molecular weight values but associated with a cross-linked structure (poor water solubility) while microwave energy addition to electron beam energy gives simultaneously high molecular weight values and high water solubility.

  18. Novel Vortex Generator and Mode Converter for Electron Beams

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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 HG10 and HG01 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.

  19. 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. PMID:23002749

  20. Electron acceleration using two crossed Bessel beams in vacuum

    NASA Astrophysics Data System (ADS)

    Zhao, Zhiguo; Lü, Baida

    2007-09-01

    The direct acceleration of electrons by using two crossed linearly polarized Bessel beams with equal frequency and amplitude in vacuum is studied and compared with the case of single linearly polarized Bessel beam. It is found that two zeroth- and first-order Bessel beams with π-rad phase difference have a nonvanishing longitudinal electric field on the z-axis, which can be maximized under certain conditions and used to accelerate electrons. Two crossed zeroth- and first-order Bessel beams have a larger maximum longitudinal electric field on the z-axis than that of a single first-order Bessel beam, and are suited for laser electron acceleration.

  1. MEASURED PROPERTIES OF THE DUVFEL HIGH BRIGHTNESS, ULTRASHORT ELECTRON BEAM.

    SciTech Connect

    GRAVES, W.S.; CARR, G.L.; DIMAURO, L.F.; DOYURAN, A.; HEESE, R.; JOHNSON, E.D.; KRINSKY, S.; NEUMAN, C.; RAKOWSKY, G.; ROSE, J.; ROTHMAN, J.; RUDATI, J.; SHAFTAN, T.; SHEEHY, B.; SKARITKA, J.; YU, L.H.; DOWELL, D.H.; EMMA, P.

    2001-06-18

    The DUVFEL electron linac is designed to produce sub-picosecond, high brightness electron bunches to drive an ultraviolet FEL. The accelerator consists of a 1.6 cell S-band photoinjector, variable pulse length Ti:Sapp laser, 4 SLAC-type S-band accelerating sections, and 4-dipole chicane bunch compressor. In preparation for FEL operation, the compressed electron beam has been fully characterized. Measurement of the beam parameters and simulation of the beam are presented.

  2. 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.

  3. The electron-beam FGT process

    NASA Astrophysics Data System (ADS)

    Frank, Norman W.; Hirano, Shinichi

    The electron-beam process is one of the most effective methods of removing SO 2 and NO x from industrial flue gases. This flue gas treatment consists of adding a small amount of ammonia to the flue gas and irradiating the gas by means of an electron beam, thereby causing reactions which convert the SO 2 and NO x to ammonium sulfate and ammonium-sulfate nitrate. These salts may then be collected from the flue gas by means of such conventional collectors as an elecrtostatic precipitator or baghouse. This process has numerous advantages over currently-used conventional processes as follows: 1) The process simultaneously removes SO 2 and NO x from flue gas at high efficiency levels; 2) It is a dry process which is easily controlled and has excellent load-following capability; 3) Stock-gas reheat is not required; 4) The pollutants are converted into a salable agricultural fertilizer; 5) The process has low capital and operating cost requirements. Test results from the most recent pilot plant in Indianapolis, Indiana, will be discussed showing various characteristics of process control, temperature relationships, radiation dosage, pollution removals at various conditions, and by-product collection usage evaluations. The results will show what will be required in future commercial installations and what accelerator equipment will be required, including various configuration of irradiation zone process design. The economic evaluation will include studies of cost sensitivity and by-product pay back. Various designs for large scale plants indicate the process will have a place in the future clean-up of environmental pollutants.

  4. Quantitative experiments with electrons in a positively charged beam

    SciTech Connect

    Molvik, A W; Vay, J; Covo, M K; Cohen, R; Baca, D; Bieniosek, F; Friedman, A; Leister, C; Lund, S M; Seidl, P; Sharp, W

    2006-12-06

    Intense ion beams are difficult to maintain as non-neutral plasmas. Experiments and simulations are used to study the complex interactions between beam ions and (unwanted) electrons. Such ''electron clouds'' limit the performance of many accelerators. To characterize electron clouds, a number of parameters are measured including: total and local electron production and loss for each of three major sources, beam potential versus time, electron line-charge density, and gas pressure within the beam. Electron control methods include surface treatments to reduce electron and gas emission, and techniques to remove electrons from the beam, or block their capture by the beam. Detailed, self-consistent simulations include beam-transport fields, and electron and gas generation and transport; these compute unexpectedly rich behavior, much of which is confirmed experimentally. For example, in a quadrupole magnetic field, ion and dense electron plasmas interact to produce multi-kV oscillations in the electron plasma and distortions of the beam velocity space distribution, without the system becoming homogeneous or locally neutral.

  5. Simple electron beam guiding system including automatic capture circuitry

    NASA Astrophysics Data System (ADS)

    Stein, W.; Schulenburg, M.; Freund, F.

    1980-08-01

    The spatial stability of the point of impact of an electron beam is a stringent requirement in some experiments such as soft x-ray spectroscopy using a focussing curved crystal spectrometer. The occasinally poor design of moderately priced electron guns, thermal instabilities, electromagnetic stray fields and so on, make spot stabilization an arduous task. The problem can be solved to some extent by a simple electron beam guiding system: a small fraction of the electron beam is captured by a metal wire mounted in the vicinity of the target. The beam position is fixed, if this fraction is controlled by a feedback loop via the deflection plates of the gun.

  6. Plasma and ion barrier for electron beam spot stability

    SciTech Connect

    Kwan, Thomas J. T.; Snell, Charles M.

    2000-03-01

    High-current electron beams of small spot size are used for high-resolution x-ray radiography of dense objects. Intense energy deposition in the bremsstrahlung target causes generation of ions which can propagate upstream and disrupt the electron beam. We have investigated the use of a thin beryllium foil placed 1-2 cm in front of the target, which serves as a barrier for the ions but is essentially transparent to the incoming electron beam. Analysis and computer simulations confirm that this confinement method will halt ion propagation and preserve the spot size stability of the electron beam. (c) 2000 American Institute of Physics.

  7. 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.

  8. 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.

  9. 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.

  10. Unveiling orbital angular momentum and acceleration of light beams and electron beams

    NASA Astrophysics Data System (ADS)

    Arie, Ady

    Special beams, such as the vortex beams that carry orbital angular momentum (OAM) and the Airy beam that preserves its shape while propagating along parabolic trajectory, have drawn significant attention recently both in light optics and in electron optics experiments. In order to utilize these beams, simple methods are needed that enable to easily quantify their defining properties, namely the OAM for the vortex beams and the nodal trajectory acceleration coefficient for the Airy beam. Here we demonstrate a straightforward method to determine these quantities by astigmatic Fourier transform of the beam. For electron beams in a transmission electron microscope, this transformation is easily realized using the condenser and objective stigmators, whereas for light beam this can be achieved using a cylindrical lens. In the case of Laguerre-Gauss vortex beams, it is already well known that applying the astigmatic Fourier transformation converts them to Hermite-Gauss beams. The topological charge (and hence the OAM) can be determined by simply counting the number of dark stripes of the Hermite-Gauss beam. We generated a series of electron vortex beams and managed to determine the topological charge up to a value of 10. The same concept of astigmatic transformation was then used to unveil the acceleration of an electron Airy beam. The shape of astigmatic-transformed depends only on the astigmatic measure and on the acceleration coefficient. This method was experimentally verified by generating electron Airy beams with different known acceleration parameters, enabling direct comparison to the deduced values from the astigmatic transformation measurements. The method can be extended to other types of waves. Specifically, we have recently used it to determine the acceleration of an optical Airy beams and the topological charge of so-called Airy-vortex light beam, i.e. an Airy light beam with an embedded vortex. This work was supported by DIP and the Israel Science

  11. Electrostatic charging of spacecraft in response to electron beam injection

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Hwang, K. S.

    1989-01-01

    Electron beam injections from spacecraft now constitute a major activity in space research. Here, the charging level of a conducting surface when an electron beam is injected from it is investigated. Injections into both vacuum and an ambient plasma are considered. When a Maxwellian beam is injected into vacuum, the surface changes to a potential much greater than the average beam energy. The dependence of this excess is examined by considering beams with water-bag types of velocity distribution functions in which no electron has a velocity V(max) above a certain value. The electric field distribution in the electron sheath near the surface is determined by the pressure distribution. Thus, the surface potential is determined not only by V(max) but by all the beam parameters. The ambient plasma reduces the charging level and causes an oscillation in the surface potential. The oscillation frequency is the electron-plasma frequency associated with the ambient plasma.

  12. 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.

  13. 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.

  14. 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.

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

    DOE PAGESBeta

    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,more » we report on the measured performance of this profile monitor.« less

  16. Quantitative Experiments With Electrons in a Positively Charged Beam

    SciTech Connect

    Molvik, A W; Vay, J; Covo, M K; Cohen, R; Baca, D; Bieniosek, F; Friedman, A; Leister, C; Lund, S M; Seidl, P; Sharp, W

    2006-10-27

    Intense ion beams are an extreme example of, and difficult to maintain as, a non-neutral plasma. Experiments and simulations are used to study the complex interactions between beam ions and (unwanted) electrons. Such ''electron clouds'' limit the performance of many accelerators. To characterize electron clouds, a number of parameters are measured including: total and local electron production and loss for each of three major sources, beam potential versus time, electron line-charge density, and gas pressure within the beam. Electron control methods include surface treatments to reduce electron and gas emission, and techniques to remove, or block, electrons from the beam. Detailed, self-consistent simulations include beam-transport fields, and electron and gas generation and consistent transport, to compute unexpectedly rich behavior, much of which is confirmed experimentally. For example, in a quadrupole magnetic field, ion and dense electron plasmas interact to produce multi-kV oscillations in the electron plasma and distortions of the beam velocity space distribution, without becoming homogenous or locally neutral.

  17. Electron beam treatment of non-conducting materials by a fore-pump-pressure plasma-cathode electron beam source

    NASA Astrophysics Data System (ADS)

    Burdovitsin, V. A.; Klimov, A. S.; Medovnik, A. V.; Oks, E. M.

    2010-10-01

    In the irradiation of an insulated target by an electron beam produced by a plasma-cathode electron beam source operating in the fore-vacuum pressure range (5-15 Pa), the target potential is much lower than the electron beam energy, offering the possibility of direct electron treatment of insulating materials. It is found that in the electron beam irradiation of a non-conducting target in a moderately high pressure range, the electron charge on the target surface is neutralized mainly by ions from a volume discharge established between the negatively charged target surface and the grounded walls of the vacuum chamber. This allows the possibility of direct electron beam treatment (heating, melting, welding) of ceramics and other non-conducting and semiconductor materials.

  18. Electron beam welder X-rays its own welds

    NASA Technical Reports Server (NTRS)

    Roden, W. A.

    1967-01-01

    Beam of an electron beam welder X rays its own welds, enabling rapid weld quality checks to be made without removing the work from the vacuum chamber. A tungsten target produces X rays when hit by the beam. They are directed at the weld specimen and recorded on polaroid film.

  19. 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.

  20. 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.

  1. 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.

  2. Head-on beam-beam compensation with electron lenses in the RHIC.

    SciTech Connect

    Luo,Y.; FischW; Abreu, N.; Beebe, E.; Montag, C.; Okamura, M.; Pikin, A.; Robert-Demolaize, G.

    2008-06-23

    The working point for the polarized proton run in the Relativistic Heavy Ion Collider is constrained between 2/3 and 7/10 in order to maintain good beam lifetime and polarization. To further increase the bunch intensity to improve the luminosity, a low energy Gaussian electron beam, or an electron lens is proposed to head-on collide with the proton beam to compensate the large tune shift and tune spread generated by the proton-proton beam-beam interactions at IP6 and IP8. In this article, we outline the scheme of head-on beam-beam compensation in the RHIC and give the layout of e-lens installation and the parameters of the proton and electron beams. The involved physics and engineering issues are shortly discussed.

  3. 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.

  4. Study of a non-intrusive electron beam radius diagnostic

    SciTech Connect

    Kwan, T.J.T.; DeVolder, B.G.; Goldstein, J.C.; Snell, C.M.

    1997-12-01

    The authors have evaluated the usefulness and limitation of a non-intrusive beam radius diagnostic which is based on the measurement of the magnetic moment of a high-current electron beam in an axisymmetric focusing magnetic field, and relates the beam root-mean-square (RMS) radius to the change in magnetic flux through a diamagnetic loop encircling the beam. An analytic formula that gives the RMS radius of the electron beam at a given axial position and a given time is derived and compared with results from a 2-D particle-in-cell code. The study has established criteria for its validity and optimal applications.

  5. Gyrotron and its Electron Beam Source: A Review

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Sinha, AK

    2012-10-01

    Microwave occupies a glorious position in the electromagnetic spectrum and in that there are a number of devices in this frequency regime which are capable of high power operations. Among them, gyrotron has proven to be an efficient source for radio frequency (RF) generation at high power level and up to very high frequency. The gyrotron consists of several components like electron beam source, interaction structure, quasi-optical launcher, collector, RF window, magnet system, etc. All the components have their distinct role in the function of the device. Among them, electron beam source also called magnetron injection gun (MIG) is the generator of electron beam and it is very essential that MIG should produce and provide electron beam suitable for the beam-wave interaction at the interaction structure for the effective power growth. The paper presents the introduction of a microwave tube, gyrotron and its components alongwith review of the previous work, the background and the applications. The functions of various components of a gyrotron are discussed with particular highlighting on the electron beam emission from the electron beam source and the beam-wave interaction for power growth in the device. A review on different types of gyrotron electron beam sources is also presented.

  6. 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.

  7. High harmonic terahertz confocal gyrotron with nonuniform electron beam

    NASA Astrophysics Data System (ADS)

    Fu, Wenjie; Guan, Xiaotong; Yan, Yang

    2016-01-01

    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.

  8. 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.

  9. 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.

  10. 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.

  11. FEL gain calculation for imperfectly matched electron beams

    NASA Astrophysics Data System (ADS)

    Swent, R. L.; Berryman, K. W.

    1995-04-01

    We present here the details of an analytical small-signal gain calculation. The analysis builds on the basic one-dimensional analytical calculation by modeling the effects of finite electron beam size and imperfect matching of the electron beam to the wiggler. The calculation uses TRANSPORT [SLAC-91, Rev. 2 (1977)] parameters to describe the electron beam in order to easily take the output of beam transport calculations and use them as the input for FEL gain calculations. The model accepts an arbitrary TRANSPORT beam and includes the effects of energy spread, beam size, betatron oscillations, and focussing in the wiggle plane. The model has allowed us to calculate the range over which our FEL can be tuned by changing the electron energy alone (i.e., without changing any magnets).

  12. Measurements on wave propagation characteristics of spiraling electron beams

    NASA Technical Reports Server (NTRS)

    Singh, A.; Getty, W. D.

    1976-01-01

    Dispersion characteristics of cyclotron-harmonic waves propagating on a neutralized spiraling electron beam immersed in a uniform axial magnetic field are studied experimentally. The experimental setup consisted of a vacuum system, an electron-gun corkscrew assembly which produces a 110-eV beam with the desired delta-function velocity distribution, a measurement region where a microwave signal is injected onto the beam to measure wavelengths, and a velocity analyzer for measuring the axial electron velocity. Results of wavelength measurements made at beam currents of 0.15, 1.0, and 2.0 mA are compared with calculated values, and undesirable effects produced by increasing the beam current are discussed. It is concluded that a suitable electron beam for studies of cyclotron-harmonic waves can be generated by the corkscrew device.

  13. 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.

  14. 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.

  15. CW silver ion laser with electron beam excitation

    NASA Astrophysics Data System (ADS)

    Wernsman, B.; Prabhuram, T.; Lewis, K.; Gonzalez, F.; Villagran, M.

    1988-08-01

    A CW laser power of 140 mW was obtained in the 840.39-nm transition of Ag II by electron-beam excitation. The electron-beam excited metal-vapor ion laser is capable of operating using metals with high vaporization temperatures, and is of interest for generation of CW coherent radiation in the 220-260-nm spectral region.

  16. Metastable atom probe for measuring electron beam density profiles

    NASA Technical Reports Server (NTRS)

    Lockhart, J. M.; Zorn, J. C.

    1972-01-01

    Metastable atom probe was developed for measuring current density in electron beam as function of two arbitrary coordinates, with spatial resolution better than 0.5 mm. Probe shows effects of space charge, magnetic fields, and other factors which influence electron current density, but operates with such low beam densities that introduced perturbation is very small.

  17. Laser and electron cooling of relativistic stored beams

    SciTech Connect

    Huber, G.; Schroeder, S.; Klein, R.; Boos, N.; Grieser, R.; Hoog, I.; Krieg, M.; Merz, P. ); Kuehl, T.; Neumann, R. ); Balykin, V.; Grieser, M.; Habs, D.; Jaeschke, E.; Petrich, W.; Schwalm, D.; Steck, M.; Wanner, B.; Wolf, A. )

    1991-08-05

    Laser cooling of ions at relativistic energies was first observed at the TSR storage ring in Heidelberg. A {sup 7}Li{sup +} ion beam moving at 6.4% the speed of light was overlapped with resonant co- and counter-propagating laser beams. The longitudinal temperatures were found to pass below 190 mK. Limits and applications of laser cooled relativistic ion beams are discussed. Laser cooling and electron cooling of the ion beam were combined.

  18. Implementation of a compact magnetic electron energy spectrometer for intense relativistic electron beams. Interim report

    SciTech Connect

    Gregor, J.A.; Antoniades, J.A.

    1993-11-05

    A diagnostic used for measuring the energy of 1 to 5 MEV pulsed electron beams by means independent of the beam generating device is investigated. The method employed is capable of collecting the required data optically in a single pulse. The beam energy is measured using a magnetic electron spectrometer coupled with a scintillating material. Using a polaroid camera to collect data, the energy of electron beams from two field emission diode accelerators is measured. The first is a nominal 1 MEV, 16 kA, 25 ns FWHM electron beam and the second is a nominal 5 MEV, 20 kA, 50 ns FWHM electron beam. A detailed study of measurement accuracy and possible sources of error was accomplished. Energy, Relativistic, Electron beam. Electron, Spectrometer.

  19. Ribbon Reduces Spiking in Electron-Beam Welding

    NASA Technical Reports Server (NTRS)

    Olson, R. E.

    1984-01-01

    Spiking in electron-beam welding reduced by placing high-vapor-pressure substance along path of electron beam. Strip of metal having vapor pressure higher than base metal at same temperature placed in slot machined along weld line. Strip vaporizes as beam strikes it, and vapor pressure keeps surface tension from closing off top of channel. Technique used successfully on nickel alloys and aluminum alloys and effective on steel and titanium.

  20. 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.

  1. Radiative instability of electron beam in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Batrakov, Konstantin G.; Kuzhir, Polina P.; Maksimenko, Sergey A.

    2006-08-01

    Basic mechanisms of the interaction of electron beam tavelling through a carbon nanotube with electromagnetic wave, resulting in the radiative instability and generation of stimulated radiation, are considered. The effect of the surface electromagnetic wave slow-down in CNT (c/v > 100) [Slepyan et al., Phys. Rev. B 60, 17136, 1999] is exploited to synchronize the wave and the beam and thus to realize the Cherenkov radiation mechanism. Alternative mechanism of the electron beam instability is proposed based on the undulator emission arising due to the interband transitions of electrons moving in nanotube. The dispersion equations of the electron beam instability and threshold conditions for the stimulated radiation are derived and studied. The analysis of the threshold conditions estimates the possibility of the stimulated emission by electron beam as realistic and attainable at present-day experimental technique.

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

    SciTech Connect

    Mirian, N. S.; Maraghechi, B.

    2013-08-15

    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.

  3. Etching with electron beam generated plasmas

    SciTech Connect

    Leonhardt, D.; Walton, S.G.; Muratore, C.; Fernsler, R.F.; Meger, R.A.

    2004-11-01

    A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen-argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm/min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was seen as gas composition went from pure oxygen to 70% argon, implying the resist removal mechanism in this system required the additional energy supplied by the ions. With silicon substrates at room temperature, mixtures of argon and sulfur hexafluoride etched approximately seven times faster (1375 nm/min) than mixtures of oxygen and sulfur hexafluoride ({approx}200 nm/min) with 200 eV ions, the difference is attributed to the passivation of the silicon by involatile silicon oxyfluoride (SiO{sub x}F{sub y}) compounds. At low incident ion energies, the Ar-SF{sub 6} mixtures showed a strong chemical (lateral) etch component before an ion-assisted regime, which started at {approx}75 eV. Etch rates were independent of the 0.5%-50% duty factors studied in this work.

  4. 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%.

  5. Electron beam cold hearth refining in Vallejo

    SciTech Connect

    Lowe, J.H.C.

    1994-12-31

    Electron Beam Cold Hearth Refining Furnace (EBCHR) in Vallejo, California is alive, well, and girding itself for developing new markets. A brief review of the twelve years experience with EBCHR in Vallejo. Acquisition of the Vallejo facility by Axel Johnson Metals, Inc. paves the way for the development of new products and markets. A discussion of some of the new opportunities for the advancement of EBCHR technology. Discussed are advantages to the EBCHR process which include: extended surface area of molten metal exposed to higher vacuum; liberation of insoluble oxide particles to the surface of the melt; higher temperatures that allowed coarse solid particles like carbides and carbonitrides to be suspended in the fluid metal as fine micro-segregates, and enhanced removal of volatile trace impurities like lead, bismuth and cadmium. Future work for the company includes the continued recycling of alloys and also fabricating stainless steel for the piping of chip assembly plants. This is to prevent `killer defects` that ruin a memory chip.

  6. Electron beam irradiation of fluoropolymers containing polyethers

    NASA Astrophysics Data System (ADS)

    Bucio, E.; Burillo, G.; Tapia, F.; Adem, E.; Cedillo, G.; Cassidy, P. E.

    2009-02-01

    A highly fluorinated monomer, 1,3-bis(1,1,1,3,3,3-hexafluoro-2-pentafluorophenyl methoxy-2-propyl)benzene (12F-FBE) was polymerized with some diphenols by polycondensation and then was electron beam irradiated between 100 and 1000 kGy to determine degradation radiochemistry yield ( Gs) by gel permeation chromatography (GPC). The samples were characterized after irradiation by DSC, FTIR, and nuclear magnetic resonance (NMR). The fluoropolymers show apparent degradation in mechanical properties at 300 kGy, except 12F-FBE polymerized with biphenol and bisphenol A, when they did not show any apparent physical change up to 300 kGy; and continue to be flexible and transparent, with a radiochemical yield scission ( Gs) of 0.75, 0.53, 0.88, and 0.38 for 12F-FBE/SDL aliphatic, 12F-FBE/biphenol, 12F-FBE/bisphenol A, and 12F-FBE/bisphenol O, respectively. The number average molecular weights for three of the polymers decrease upon 1000 kGy irradiation to 10% of their original values; however, the polymer from bisphenol A is much more stable and its Mn decreases to only 24% of original.

  7. 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.

  8. Recent Progress On Submicron Electron Beam Lithography

    NASA Astrophysics Data System (ADS)

    Takigawa, Tadahiro; Shimazaki, Kuniya; Kusui, Naoki

    1986-06-01

    In order to fabricate submicron pattern, total electron beam (EB) lithography system has been developed. Upper submicron pattern will be realized by optical lithography, which requires reticle with high accuracy. An EB writing system, EBM-130/40, has the performance of drawing capability of 4 M bit DRAM reticle pattern in about 40 minutes. The EB system incorporated with peripheral technologies including data compaction conversion software, reticle inspection system, APC-130R, and EBR-9 resist process can produce advanced reticles of number of about 600 per month. For lower submicron pattern formation, next generation lithography system is required. The EBM-130V is the variable shaped EB system with high acceleration voltage of 50 kV and high dosage of 50 μC/cm2 for direct writing and X-ray mask fabrication for development of the high bit density VLSI pattern. This system makes possible EB/optical combined lithography. Its metrology function allows it to measure X-ray mask distortion.

  9. 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.

  10. 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.

  11. 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.

  12. Elastic Scattering of Electron Vortex Beams in Magnetic Matter

    NASA Astrophysics Data System (ADS)

    Edström, Alexander; Lubk, Axel; Rusz, Ján

    2016-03-01

    Elastic scattering of electron vortex beams on magnetic materials leads to a weak magnetic contrast due to Zeeman interaction of orbital angular momentum of the beam with magnetic fields in the sample. The magnetic signal manifests itself as a redistribution of intensity in diffraction patterns due to a change of sign of the orbital angular momentum of the electron vortex beam. While in the atomic resolution regime the magnetic signal is most likely under the detection limits of present transmission electron microscopes, for electron probes with high orbital angular momenta, and correspondingly larger spatial extent, its detection is predicted to be feasible.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Focused electron beam induced deposition as a tool to create electron vortices.

    PubMed

    Béché, A; Winkler, R; Plank, H; Hofer, F; Verbeeck, J

    2016-01-01

    Focused electron beam induced deposition (FEBID) is a microscopic technique that allows geometrically controlled material deposition with very high spatial resolution. This technique was used to create a spiral aperture capable of generating electron vortex beams in a transmission electron microscope (TEM). The vortex was then fully characterized using different TEM techniques, estimating the average orbital angular momentum to be ∼0.8ℏ per electron with almost 60% of the beam ending up in the ℓ=1 state. PMID:26432987

  18. 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.

  19. Aperture Effects and Mismatch Oscillations in an Intense Electron Beam

    SciTech Connect

    Harris, J R; O'Shea, P G

    2008-05-12

    When an electron beam is apertured, the transmitted beam current is the product of the incident beam current density and the aperture area. Space charge forces generally cause an increase in incident beam current to result in an increase in incident beam spot size. Under certain circumstances, the spot size will increase faster than the current, resulting in a decrease in current extracted from the aperture. When using a gridded electron gun, this can give rise to negative transconductance. In this paper, we explore this effect in the case of an intense beam propagating in a uniform focusing channel. We show that proper placement of the aperture can decouple the current extracted from the aperture from fluctuations in the source current, and that apertures can serve to alter longitudinal space charge wave propagation by changing the relative contribution of velocity and current modulation present in the beam.

  20. Electron beam energy QA - a note on measurement tolerances.

    PubMed

    Meyer, Juergen; Nyflot, Matthew J; Smith, Wade P; Wottoon, Landon S; Young, Lori; Yang, Fei; Kim, Minsun; Hendrickson, Kristi R G; Ford, Eric; Kalet, Alan M; Cao, Ning; Dempsey, Claire; Sandison, George A

    2016-01-01

    Monthly QA is recommended to verify the constancy of high-energy electron beams generated for clinical use by linear accelerators. The tolerances are defined as 2%/2 mm in beam penetration according to AAPM task group report 142. The practical implementation is typically achieved by measuring the ratio of readings at two different depths, preferably near the depth of maximum dose and at the depth corresponding to half the dose maximum. Based on beam commissioning data, we show that the relationship between the ranges of energy ratios for different electron energies is highly nonlinear. We provide a formalism that translates measurement deviations in the reference ratios into change in beam penetration for electron energies for six Elekta (6-18 MeV) and eight Varian (6-22 MeV) electron beams. Experimental checks were conducted for each Elekta energy to compare calcu-lated values with measurements, and it was shown that they are in agreement. For example, for a 6 MeV beam a deviation in the measured ionization ratio of ± 15% might still be acceptable (i.e., be within ± 2 mm), whereas for an 18 MeV beam the corresponding tolerance might be ± 6%. These values strongly depend on the initial ratio chosen. In summary, the relationship between differences of the ionization ratio and the corresponding beam energy are derived. The findings can be translated into acceptable tolerance values for monthly QA of electron beam energies. PMID:27074488

  1. 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

  2. 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

    2012-01-01

    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

  3. Progress report on beam-beam compensation with electron lenses in Tevatron

    SciTech Connect

    Vladimir Shiltsev et al.

    2003-07-09

    We discuss the original idea of beam-beam compensation (BBC) in Section I, sequence of events in 2001-2002 and use of the Tevatron Electron Beam (TEL) for DC beam removal in Section II, (anti)proton lifetime improvement in Section III, experimental data on the BBC attempts in Section IV and, conclusively, Section V is devoted to discussion on important phenomena, needed improvements and future plans.

  4. Renormalization theory of beam-beam interaction in electron-positron colliders

    SciTech Connect

    Chin, Y.H.

    1989-07-01

    This note is devoted to explaining the essence of the renormalization theory of beam-beam interaction for carrying out analytical calculations of equilibrium particle distributions in electron-positron colliding beam storage rings. Some new numerical examples are presented such as for betatron tune dependence of the rms beam size. The theory shows reasonably good agreements with the results of computer simulations. 5 refs., 6 figs.

  5. Comprehensive, nonintercepting electron-beam diagnostics using spontaneous emission

    SciTech Connect

    Lumpkin, A.H.

    1989-01-01

    Characterization and optimization of electron-beam parameters are important aspects of optimizing free-electron laser (FEL) performance. The visible spontaneous emission ({lambda}{approximately}650 nm) from the 5-meter long undulator of the Boeing FEL experiment can be characterized in sufficient detail with a streak/spectrometer to deduce time-resolved electron-beam spatial position and profile, micropulse duration, and energy. 7 refs., 13 figs., 2 tabs.

  6. 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.

  7. An electron beam injector for pulse compression experiments

    SciTech Connect

    Wang, J.G.; Boggasch, E.; Kehne, D.; Reiser, M.; Shea, T.; Wang, D.X.

    1990-01-01

    An electron beam injector has been constructed to study the physics of longitudal pulse compression in the University of Maryland electron beam transport experiment. The injector consists of a variable-perveance gridded electron gun followed by three matching lenses and one induction linac module. It produces a 50 ns, 40 mA electron pulse with a 2.5 to 7.5 keV, quadratically time-dependent energy shear. This beam will be injected into the existing 5-m long periodic transport channel with 38 short solenoid lenses. With the given beam parameters and initial conditions the pulse will be compressed by a factor of 4 to 5 before reaching the end of the existing solenoid channel. This paper reports on the design features and the measured general performance characteristics of the injector system including its mechanical, electrical, and beam-optical properties.

  8. 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

  9. Application of optical beams to electrons in graphene

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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.

  10. Laser cooling of electron beams for linear colliders

    SciTech Connect

    Telnov, V.

    1996-10-01

    A novel method of electron beam cooling is considered which can be used for linear colliders. The electron beam is cooled during collision with focused powerful laser pulse. With reasonable laser parameters (laser flash energy about 10 J) one can decrease transverse beam emittances by a factor about 10 per one stage. The ultimate transverse emittances are much below that given by other methods. Depolarization of a beam during the cooling is about 5--15% for one stage. This method is especially useful for photon colliders and open new possibilities for e{sup +}e{sup {minus}} colliders and x-ray FEL based on high energy linacs.

  11. Excitation of symmetric surface wavesby electron tubular beams

    NASA Astrophysics Data System (ADS)

    Akimov, Yu A.; Olefir, V. P.; Azarenkov, N. A.

    2006-08-01

    The nonlinear theory of symmetric surface wave excitation by a low-density electron tubular beam in a cylindrical plasma-vacuum-metal waveguide is presented. A set of nonlinear equations is derived that describes the time evolution of the plasma-beam interaction. The influence of the beam and waveguide structure parameters on the saturation amplitude and excitation efficiency of the surface wave is investigated both numerically and analytically. Thermalization of the electron beam in the wave-fields is studied as well.

  12. 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

  13. 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.

  14. Non-invasive measurments of intense relativistic electron beam size

    NASA Astrophysics Data System (ADS)

    Ekdahl, Carl; McCuistian, Trent; Moir, David; Rodriguez, Patrick; Broste, William; Johnson, Jeff

    2000-10-01

    To understand relativistic electron beam transport dynamics the size of the beam is often measured using invasive techniques such as imaging the Cerenkov or OTR light emitted from a screen inserted into the beam. These techniques would completely disrupt the DARHT 2 beam, so we are developing a non-invasive method using diamagnetic loops. We show that through conservation of canonical angular momentum the RMS radius of the beam can be found by measuring the magnetic flux excluded by the diamagnetic beam. Furthermore, this measurement is shown to be independent of the details of the beam radial current profile for DARHT 2 parameters. We present results from our test and calibration experiments, as well as results of beam radius measurements on the 20-MeV DARHT 1 accelerator.

  15. A microwave plasma cathode electron gun for ion beam neutralization

    NASA Astrophysics Data System (ADS)

    Fusellier, C.; Wartski, L.; Aubert, J.; Schwebel, C.; Coste, Ph.; Chabrier, A.

    1998-02-01

    It is well known that there exist two distinct types of ion beam neutralization, viz., charge and current neutralization. We have designed and studied a versatile and compact microwave plasma (MP) cathode electron gun dedicated to charge as well as current neutralization. Unlike the conventional hot cathode neutralizer, this MP cathode allows operation of the electron gun in a reactive gaseous environment when it is eventually associated with an electron cyclotron resonance (ECR) ion gun. Charge neutralization can be easily carried out by extracting from the MP cathode through a 1 mm diameter hole, a 35 mA electron beam under a 20 V voltage; the MP cathode being fed with a 75 W microwave power at 2.45 GHz. Higher beam intensities could be obtained using a multiaperture thin plate. Electron beam intensities as high as 300 mA and energies of 2 keV needed for current neutralization, e.g., when an ion beam impinges onto a thick dielectric surface, are obtained via a two-stage arrangement including an anodic chamber associated with a set of three monoaperture plates for the electron beam extraction. Transport of 200-2000 eV electron beams is ensured using focusing optics composed of three aligned tubes 6 cm in diameter and unsymmetrically polarized.

  16. UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC

    SciTech Connect

    Bakeman, M.S.; Fawley, W.M.; Leemans, W. P.; Nakamura, K.; Robinson, K.E.; Schroeder, C.B.; Toth, C.

    2009-05-04

    to couple the THUNDER undulator to the LOASIS Lawrence Berkeley National Laboratory (LBNL) laser wakefield accelerator (LWFA). Currently the LWFA has achieved quasi-monoenergetic electron beams with energies up to 1 GeV. These ultra-short, high-peak-current, electron beams are ideal for driving a compact XUV free electron laser (FEL). Understanding the electron beam properties such as the energy spread and emittance is critical for achieving high quality light sources with high brightness. By using an insertion device such as an undulator and observing changes in the spontaneous emission spectrum, the electron beam energy spread and emittance can be measured with high precision. The initial experiments will use spontaneous emission from 1.5 m of undulator. Later experiments will use up to 5 m of undulator with a goal of a high gain, XUV FEL.

  17. 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.

  18. Investigation Of PETN Monocrystals Initiation By Electron Beams

    SciTech Connect

    Loboiko, B. G.; Garmasheva, N. V.; Filin, V. P.; Gromov, V. T.; Shukailo, V. P.; Stryakhnin, V. L.; Nesterov, O. V.; Khruliova, O. V.; Alekseev, A. V.; Gagarin, A. L.; Taybinov, N. P.

    2006-08-03

    Electron beam initiation of PETN monocrystals depending on their size and defectiveness as well as electron beam parameters and environmental acoustic stiffness, was investigated. The length of PETN monocrystals was from 1 mm to 30 mm. The experiments used pulsed accelerator of electrons GIN-540 with the average beam-current value of {approx}1kA, pulse length of {tau}0.5{approx_equal}10 ns, the average electron energy of {approx}250keV. The experiments showed that the low level of fluence of electrons led to the appearance of additional defects in PETN crystals. When fluence of electrons increased the different experimental results were observed: crystal destruction, initiation of crystal explosive decomposition, sample detonation to form a mark on witness plate. The fixed parameters of electron action showed the dependence of experimental results on acoustic stiffness of a reference plate material.

  19. 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.

  20. Electron Beam Freeform Fabrication in the Space Environment

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Taminger, Karen M. B.; Bird, R. Keith

    2007-01-01

    The influence of reduced gravitational forces (in space and on the lunar or Martian surfaces) on manufacturing processes must be understood for effective fabrication and repair of structures and replacement parts during long duration space missions. The electron beam freeform fabrication (EBF3) process uses an electron beam and wire to fabricate metallic structures. The process efficiencies of the electron beam and the solid wire feedstock make the EBF3 process attractive for use in-space. This paper will describe the suitability of the EBF3 process in the space environment and will highlight preliminary testing of the EBF3 process in a zero-gravity environment.

  1. Electron beam guiding by strong longitudinal magnetic fields

    NASA Astrophysics Data System (ADS)

    Johzaki, T.; Mima, K.; Fujioka, S.; Sakagami, H.; Sunahara, A.; Nagatomo, H.; Shiraga, H.

    2016-03-01

    In electron-driven fast ignition, the guiding of fast electron beam having significantly large beam divergence is one of the most critical issues for efficient core heating. To guide the fast electron beam to the core, we consider to externally apply longitudinal magnetic fields. From the 2D PIC simulations applying uniform magnetic fields, it was shown that the field strength of 1∼10kT is required for efficient guiding for the heating laser intensity of 1018∼1020W/cm2.

  2. 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.

  3. 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.

  4. 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.

  5. Electron-beam multicharge ion source IMI-2

    NASA Astrophysics Data System (ADS)

    Abdul'manov, V. G.; Dement'ev, E. N.; Miginskaya, E. G.; Mironenko, L. A.; Pirogov, O. V.; Tomilov, V. P.; Tsukanov, V. M.

    2000-08-01

    The main parameters of the electron beam multicharge ion source IMI-2 are given. Experimental results are also given. The IMI-2 electron-beam system (EBS) includes a short-focus electron gyn with a spherical cathode of diameter 16 mm and curvature radius of 9.5 mm. The perveance of the gun is 1,6 (mu) A/V3/2. The electron beam current can reach 2.5 A. An electrostatic and magnetic beam compression of ~103 allows one to obtain a density of the electron beam of not less than ~103 A/cm2 on a 30 cm length. A specific method of dosed injection of the atoms of solid-state elements to an ion trap by means of local pulse deflection of the electron beam was used in the facility 1. The electron-beam ion source (EBIS) IMI-2, Fig. 1, has a vertical design with an electron gun in the top section. The electron gun is mounted in a vacuum chamber of diameter 160 mm and length 500 mm. The vacuum chamber having a drift structure is inside the classical water-cooled solenoid with a completely closed magnetic circuit. An electron collector, an ion line, and a magnetic analyzer are located in the lower section of the facility. Like IMI-1 7-9, IMI-2 2-6 was also designed at the Budker Institute of Nuclear Physics for production of multicharge beams of gaseous and solid elements. In the EBS parameters, IMI-2 is intermediate between first-generation EBIS and those that can be used at acceleration complexes developed at the present time.

  6. Measurement of power density distribution and beam waist simulation for electron beam

    NASA Astrophysics Data System (ADS)

    Shen, Chunlong; Peng, Yong; Wang, Kehong; Zhou, Qi

    2013-02-01

    The study aims to measure the power density distribution of the electron beam (EB) for further estimating its characteristics. A compact device combining deflection signal controller and current signal acquisition circuit of the EB was built. A software modelling framework was developed to investigate structural parameters of the electron beam. With an iterative algorithm, the functional relationship between the electron beam power and its power density was solved and the corresponding contour map of power density distribution was plotted through isoline tracking approach. The power density distribution of various layers of cross-section beam was reconstructed for beam volume by direct volume rendering technique. The further simulation of beam waist with all-known marching cubes algorithm reveals the evolution of spatial appearance and geometry measurement principle was explained in detail. The study provides an evaluation of promising to replace the traditional idea of EB spatial characteristics.

  7. Characteristics of an electron-beam rocket pellet accelerator

    SciTech Connect

    Tsai, C.C.; Foster, C.A.; Milora, S.L.; Schechter, D.E.

    1991-01-01

    A proof-of-principle (POP) electron-beam pellet accelerator has been developed and used for accelerating hydrogen and deuterium pellets. An intact hydrogen pellet was accelerated to a speed of 460 m/s by an electron beam of 13.5 keV. 0.3 A, and 2 ms. The maximum speed is limited by the acceleration path length (0.4 m) and pellet integrity. Experimental data have been collected for several hundred hydrogen pellets, which were accelerated by electron beams with parameters of voltage up to 16 kV, current up to 0.4 A, and pulse length up to 10 ms. Preliminary results reveal that the measured burn velocity increases roughly with the square of the beam voltage, as the theoretical model predicts. The final pellet velocity is proportional to the exhaust velocity, which increases with the beam power. To reach the high exhaust velocity needed for accelerating pellets to >1000 m/s, a new electron gun, with its cathode indirectly heated by a graphite heater and an electron beam, is being developed to increase beam current and power. A rocket casing or shell around the pellet has been designed and developed to increase pellet strength and improve the electron-rocket coupling efficiency. We present the characteristics of this pellet accelerator, including new improvements. 13 refs., 6 figs.

  8. Instability of Interaction of a Coherent Electron Beam and Plasma

    NASA Astrophysics Data System (ADS)

    Matveev, A. I.

    2015-12-01

    Nonlinear interaction of a beam with finite density of electrons, whose velocity is greater than the phase velocity of a plasma wave, with homogeneous collisionless plasma is described. It is shown that a positive feedback arises between plasma oscillations and the wave of longitudinal electron density of the beam if the phase of this wave is 90° ahead of the phase of plasma oscillations. An increase in the energies of plasma and beam oscillations is accompanied by a decrease in the kinetic beam energy until the moment when the beam velocity becomes equal to the plasma wave phase velocity. Since the beam velocity can be greater than the plasma wave phase velocity, such energy conversion is very efficient.

  9. Effects of electron-beam irradiation on conducting polypyrrole nanowires

    SciTech Connect

    Hong, Young Ki; Park, Dong Hyuk; Park, Se Hee; Park, Soung Kyu; Joo, Jinsoo

    2009-02-02

    Conducting polypyrrole (PPy) nanowires (NWs) were irradiated by a relatively high energy (300 keV-2 MeV) electron-beam (e-beam) generated from a linear electron accelerator in an atmospheric environment. From the current-voltage characteristics of pristine and 2 MeV e-beam irradiated PPy NWs, we observed a dramatic variation in resistance from 8.0x10{sup 2} to 1.45x10{sup 8} {omega}, that is, we observed a transition from conducting states to nonconducting states through the e-beam irradiation. To discern conformational changes and the doping states of PPy NWs through the e-beam irradiation, we measured Raman and ultraviolet-visible absorption spectra for the PPy NWs. As the energy of the e-beam irradiation increased, we observed that the PPy NWs were changed from doping states to dedoping states with conformational modification including the variation in {pi}-conjugation length.

  10. 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.

  11. 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.

  12. Transmission of Megawatt Relativistic Electron Beams Through Millimeter Apertures

    SciTech Connect

    Arizona State University; Arizona State University; JLAB; MIT; College of William and Mary, JLAB; MIT; JLAB; JLAB; MIT; MIT; Hampton University; MIT; JLAB; MIT; JLAB; MIT; MIT; JLAB; MIT; JLAB; JLAB

    2013-10-01

    High power, relativistic electron beams from energy recovery linacs have great potential to realize new experimental paradigms for pioneering research in fundamental and applied research. A major design consideration for these new generation of experimental capabilities is the understanding of the halo associated with these bright, intense beams. In this Letter, we report on measurements performed using the 100 MeV, 430 kWatt CW electron beam from the energy recovery linac at the Jeff#11;erson Laboratory's Free Electron Laser facility as it traversed a set of small apertures in a 127 mm long aluminum block. Thermal measurements of the block together with neutron measurements near the beam-target interaction point yielded a consistent understanding of the beam losses. These were determined to be 3 ppm through a 2 mm diameter aperture and were maintained during a 7 hour continuous run.

  13. 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.

  14. 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.

  15. Optimization of electron beam crosslinking of wire and cable insulation

    NASA Astrophysics Data System (ADS)

    Zimek, Zbigniew; Przybytniak, Grażyna; Nowicki, Andrzej

    2012-09-01

    The computer simulations based on Monte Carlo (MC) method and the ModeCEB software were carried out in connection with electron beam (EB) radiation set-up for crosslinking of electric wire and cable insulation. The theoretical predictions for absorbed dose distribution in irradiated electric insulation induced by scanned EB were compared to the experimental results of irradiation that was carried out in the experimental set-up based on ILU 6 electron accelerator with electron energy 0.5-2.0 MeV. The computer simulation of the dose distributions in two-sided irradiation system by a scanned electron beam in multilayer circular objects was performed for various process parameters, namely electric wire and cable geometry (thickness of insulation layers and copper wire diameter), type of polymer insulation, electron energy, energy spread and geometry of electron beam, electric wire and cable layout in irradiation zone. The geometry of electron beam distribution in the irradiation zone was measured using CTA and PVC foil dosimeters for available electron energy range. The temperature rise of the irradiated electric wire and irradiation homogeneity were evaluated for different experimental conditions to optimize technological process parameters. The results of computer simulation are consistent with the experimental data of dose distribution evaluated by gel-fraction measurements. Such conformity indicates that ModeCEB computer simulation is reliable and sufficient for optimization absorbed dose distribution in the multi-layer circular objects irradiated with scanned electron beams.

  16. 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.

  17. 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.

  18. Relativistic Electron Vortex Beams in a Laser Field.

    PubMed

    Bandyopadhyay, Pratul; Basu, Banasri; Chowdhury, Debashree

    2015-11-01

    The orbital angular momentum Hall effect and the spin Hall effect of electron vortex beams (EVBs) have been studied for the EVBs interacting with a laser field. In the scenario of a paraxial beam, the cumulative effect of the orbit-orbit interaction of EVBs and laser fields drives the orbital Hall effect, which in turn produces a shift of the center of the beam from that of the field-free case towards the polarization axis of the photons. In addition, for nonparaxial beams one can also perceive a similar shift of the center of the beam owing to the spin Hall effect involving spin-orbit interaction. Our analysis suggests that the shift in the paraxial beams will always be larger than that in the nonparaxial beams. PMID:26588389

  19. Transport of electron beams with initial transverse-longitudinal correlation

    NASA Astrophysics Data System (ADS)

    Harris, J. R.; Lewellen, J. W.; Poole, B. R.

    2013-08-01

    When an electron beam whose current varies in time is extracted from a DC gun, the competition between the time-dependent space charge force and the time-independent focusing force will cause a correlation between radius, divergence, current, and position along the beam. This correlation will determine the beam's configuration in trace space, and together with the design of the downstream transport system, will determine the quality of the transport solutions that can be obtained, including the amplitude of the mismatch oscillations occurring in each slice of the beam. Recent simulations of a simplified diode with Pierce-type focusing operating at nonrelativistic voltages indicated that the radius and divergence of beams extracted from such guns can be approximated to high accuracy as linear functions of current. Here, we consider the impact of this dependence on the beam configuration in trace space and investigate the implications for matching and transport of such correlated beams in uniform linear focusing channels.

  20. Electron Cooling for Cold Beam Synchrotron for Cancer Therapy

    SciTech Connect

    Grishanov, B.; Parkhomchuk, V.; Rastigeev, S.; Reva, V.; Vostrikov, V.; Kumada, M.

    2006-03-20

    A wide usage of carbon ions for cancer therapy is limited mostly due to technical difficulties, resulting in higher cost. This cost problem can be solved by our CBS (Cold Beam Synchrotron) proposal. In this paper a conceptual design of the facility for the carbon beam cancer therapy using a high precise active beam scanning system of synchronizing with respiration. The main feature of the CBS facility is an application of electron cooling device. The use of cold ion beam allows to decrease the aperture of synchrotron and components of high energy beam transport lines, significantly. The precise ion beam energy variation and two unique schemes of beam extraction ('pellet' extraction and extraction on recombination) enclose the list of possibilities appearing with EC applying.

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

    PubMed

    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

    2007-04-01

    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. PMID:17477653

  2. 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.

  3. Measurement of velocity spread of axis-encircling electron beam

    SciTech Connect

    Park, G.S.; Park, S.Y.; Choi, J.J.

    1995-12-31

    To achieve high efficient harmonic gyro-amplifier, gyro-peniotron research is underway at NRL using axis-encircling beam and magnetron-type slotted waveguide structure. The device performance depends critically on the quality of the electron beam. After several years` efforts, a new type axis-encircling gun with triple pole piece and center post, has been designed and fabricated by Litton. Electron ray trajectory calculations for the gun, performed using the deformable mesh code DEMEOS at Litton, indicate that the beam can be realizable at beam velocity ratio({alpha}) of 2 using 70kV, 3.5A beam. The microperveance of the beam was measured to be 0.216 up to 70kV. Experimental work is in progress to characterize the electron beam {alpha} and electron beam alignment using capacitive probes, and axial velocity spread using a movable collector. Initial test shows the measurement agrees reasonably well with the simulation. The detailed experimental results will be presented and compared with simulation.

  4. 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.

  5. 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.

  6. A determination of the current density in electron beams

    NASA Technical Reports Server (NTRS)

    Beil, R. J.

    1982-01-01

    Current gathering rotating probe techniques were used to examine the envelope shape and power density profile of electron beams used in electron beam welding devices. The electron power density contours which determine the shape of the weld vapor cavity, penetration, and local heat distribution were considered. A mathematical analysis consistent with a rotating probe technique necessary to determine the current density distribution (assumed symmetrically radial) in a cross-section of the beam is provided. An explanation of the experimental technique for obtaining data, a BASIC language computer program to determine the current density from the data, and a study indicating the level of confidence to be associated with results obtained are also provided. An example of the application of the analysis to some experimental electron beam data is included.

  7. 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.

  8. Advances in Defocused-Beam Electron-Probe Microanalysis

    NASA Astrophysics Data System (ADS)

    Carpenter, P. K.; Zeigler, R. A.; Jolliff, B. L.

    2010-03-01

    Advances in defocused-beam electron-probe microanalysis are presented, with an Excel VBA algorithm which uses a polynomial alpha factor correction algorithm coupled with a catanorm procedure to correct DBA data.

  9. NOTE: Blood irradiation with accelerator produced electron beams

    NASA Astrophysics Data System (ADS)

    Butson, M. J.; Cheung, T.; Yu, P. K. N.; Stokes, M. J.

    2000-11-01

    Blood and blood products are irradiated with gamma rays to reduce the risk of graft versus host disease (GVHD). A simple technique using electron beams produced by a medical linear accelerator has been studied to evaluate irradiation of blood and blood products. Variations in applied doses for a single field 20 MeV electron beam are measured in a phantom study. Doses have been verified with ionization chambers and commercial diode detectors. Results show that the blood product volume can be given a relatively homogeneous dose to within 6% using 20 MeV electrons without the need to rotate the blood bags or the beam entry point. The irradiation process takes approximately 6.5 minutes for 30 Gy applied dose to complete as opposed to 12 minutes for a dual field x-ray field irradiation at our centre. Electron beams can be used to satisfactorily irradiate blood and blood products in a minimal amount of time.

  10. Brushless dc motor uses electron beam switching tube as commutator

    NASA Technical Reports Server (NTRS)

    Studer, P.

    1965-01-01

    Electron beam switching tube eliminates physical contact between rotor and stator in brushless dc motor. The tube and associated circuitry control the output of a dc source to sequentially energize the motor stator windings.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  13. Electron beam seals outer surfaces of porous bodies

    NASA Technical Reports Server (NTRS)

    Herz, W. H.; Kurtz, A. D.; Kurtz, R. A.

    1966-01-01

    Porous tungsten plugs provide even airflow for frictionless bearings used in air bearing supported gyros. The plugs have their outer cylindrical surface sealed by an electron beam process to ensure unidirectional airflow through their exit ends.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26639760

  15. 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.

  16. 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.

  17. Design and operation of the electron beam ion trap

    SciTech Connect

    Vogel, D.

    1990-05-30

    This report describes the basic features and operating principles of the Electron Beam Ion Trap. The differences between EBIT and other sources of highly charged ions are outlined. Its features and operating parameters are discussed. The report also explains why certain design choices were necessary and the constraints involved in building an electron beam ion trap. EBIT's evaporation cooling system is described in detail. 13 refs., 8 figs.

  18. Theory And Design Of Thermionic Electron Beam Guns

    SciTech Connect

    Iqbal, Munawar; Fazal-e-Aleem

    2005-03-17

    Electron beam technology has a long history and wide applications in various fields including high-energy physics. The unique properties, which one can develop by using different configurations, have been one of the strongest driving forces for this multi-dimensional technology. In this paper, we will take up the subject along with applications in various areas of physics. We will particularly focus on the developments of electron beam sources by our laboratory.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Beam dump experiment at future electron-positron colliders

    NASA Astrophysics Data System (ADS)

    Kanemura, Shinya; Moroi, Takeo; Tanabe, Tomohiko

    2015-12-01

    We propose a new beam dump experiment at future colliders with electron (e-) and positron (e+) beams, BDee, which will provide a new possibility to search for hidden particles, like hidden photon. If a particle detector is installed behind the beam dump, it can detect the signal of in-flight decay of the hidden particles produced by the scatterings of e± beams off materials for dumping. We show that, compared to past experiments, BDee (in particular BDee at e+e- linear collider) significantly enlarges the parameter region where the signal of the hidden particle can be discovered.

  4. Acceleration of electrons by a tightly focused intense laser beam.

    PubMed

    Li, Jian-Xing; Zang, Wei-Ping; Li, Ya-Dong; Tian, Jian-Guo

    2009-07-01

    The recent proposal to use Weinger transformation field (WTF) [Opt. Express 17, 4959-4969 (2009)] for describing tightly focused laser beams is investigated here in detail. In order to validate the accuracy of WTF, we derive the numerical field (NF) from the plane wave spectrum method. WTF is compared with NF and Lax series field (LSF). Results show that LSF is accurate close to the beam axis and divergent far from the beam axis, and WTF is always accurate. Moreover, electron dynamics in a tightly focused intense laser beam are simulated by LSF, WTF and NF, respectively. The results obtained by WTF are shown to be accurate. PMID:19582099

  5. Anomalous broadening of energy distributions in photoemitted electron beams

    NASA Astrophysics Data System (ADS)

    Guidi, Vincenzo

    1996-06-01

    Photoemission is widely used to generate electron beams with an energy spread lower than by thermoemission. However, when a photocathode is illuminated by a multimode laser this feature is lost and an electron beam with several eV of energy spread is produced. We have developed an explanation for this anomalous behavior pointing out its origin in the combined effect of charge relaxation, taking place within the beam, together with the modulation of the laser power imposed by laser modes. The model permits a correct interpretation overall experimental evidences.

  6. Neoclassical electron transport in tokamaks with neutral-beam injection

    SciTech Connect

    Helander, P.; Akers, R.J.

    2005-04-15

    The collisional interaction between neutral-beam ions and bulk plasma electrons leads to convective transport of particles and energy similar to the well-known Ware pinch. These transport fluxes are calculated, and it is found that the particle flux is outward when the neutral beams are in the same direction as the plasma current and inward otherwise, while the opposite holds for the electron heat transport. This effectively shifts the neutral-beam fueling profile approximately one fast-ion banana width outward during coinjection and inward during counterinjection, and could help to explain why very different plasma behavior is sometimes observed when the direction of the plasma current is reversed.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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/cm2 at 13.5 mm in the post-anode region which is more than two-fold (33 kW/cm2), 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.

  8. 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.

  9. 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

  10. Superconducting nanowires by electron-beam-induced deposition

    NASA Astrophysics Data System (ADS)

    Sengupta, Shamashis; Li, Chuan; Baumier, Cedric; Kasumov, Alik; Guéron, S.; Bouchiat, H.; Fortuna, F.

    2015-01-01

    Superconducting nanowires can be fabricated by decomposition of an organometallic gas using a focused beam of Ga ions. However, physical damage and unintentional doping often result from the exposure to the ion beam, motivating the search for a means to achieve similar structures with a beam of electrons instead of ions. This has so far remained an experimental challenge. We report the fabrication of superconducting tungsten nanowires by electron-beam-induced-deposition, with critical temperature of 2.0 K and critical magnetic field of 3.7 T, and compare them with superconducting wires made with ions. This work is an important development for the template-free realization of nanoscale superconducting devices, without the requirement of an ion beam column.

  11. Superconducting nanowires by electron-beam-induced deposition

    SciTech Connect

    Sengupta, Shamashis; Li, Chuan; Guéron, S.; Bouchiat, H.; Baumier, Cedric; Fortuna, F.; Kasumov, Alik

    2015-01-26

    Superconducting nanowires can be fabricated by decomposition of an organometallic gas using a focused beam of Ga ions. However, physical damage and unintentional doping often result from the exposure to the ion beam, motivating the search for a means to achieve similar structures with a beam of electrons instead of ions. This has so far remained an experimental challenge. We report the fabrication of superconducting tungsten nanowires by electron-beam-induced-deposition, with critical temperature of 2.0 K and critical magnetic field of 3.7 T, and compare them with superconducting wires made with ions. This work is an important development for the template-free realization of nanoscale superconducting devices, without the requirement of an ion beam column.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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.

  13. 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

    2016-06-01

    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. PMID:27211080

  14. Radiation from long pulse train electron beams in space plasmas

    NASA Technical Reports Server (NTRS)

    Harker, K. J.; Banks, P. M.

    1985-01-01

    A previous study of electromagnetic radiation from a finite train of electron pulses is extended to an infinite train of such pulses. The electrons are assumed to follow an idealized helical path through a space plasma in such a manner as to retain their respective position within the beam. This leads to radiation by coherent spontaneous emission. The waves of interest in this region are the whistler slow (compressional) and fast (torsional) Alfven waves. Although a general theory is developed, analysis is then restricted to two approximations, the short and long electron beam. Formulas for the radiation per unit solid angle from the short beam are presented as a function of both propagation and ray angles, electron beam pulse width and separation and beam current, voltage, and pitch angle. Similar formulas for the total power radiated from the long beam are derived as a function of frequency, propagation angle, and ray angle. Predictions of the power radiated are presented for representative examples as determined by the long beam theory.

  15. An electron beam profile instrument based on FBGs.

    PubMed

    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

  16. 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

  17. Improved electron beam weld design and control with beam current profile measurements

    NASA Astrophysics Data System (ADS)

    Giedt, Warren H.

    The determination of machine settings for making an electron beam weld still involves trial and error tests. Also, even after settings are selected, serious variations in penetration may occur. Results are presented to demonstrate that improved weld consistency and quality can be obtained with measurement of the beam size and intensity distribution.

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

    DOE PAGESBeta

    Gu, X.; Altinbas, Z.; Costanzo, M.; Fischer, W.; Gassner, D. M.; Hock, J.; Luo, Y.; Miller, T.; Tan, Y.; Thieberger, P.; et al

    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

  19. 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.

  20. 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.

  1. Progress on standardization of electron beam dosimetry for radiation processing

    NASA Astrophysics Data System (ADS)

    Chenghua, Li; Yanli, Zhang; Ruicao, Pang; Zhimian, Liu; Xuan, Xia; Jingmin, Wu

    1993-10-01

    The high dose standards and dissemination system of electron beams are being established at NIM. The graphite and/ or water calorimeters and liquid chemical dosimeter are to be accepted as standards. The transfer dosimeter selected are alanine/ESR dosimeter and radiochromic film (FWT - 60). Several kinds of radiochromic films, undyed cellulose triacetate, polyethylene and blue cellophane will be recommended as working dosimeter. A series of intercomparison studies are conducted between calorimeter and dichromate dosimeter. Agreement is found within 2%. Water calorimeters and dichromate dosimeters are used to make absolute dosimetric measurements of electron beams. These calibrated beams are then used to calibrate several types of dosimeters, such as alanine, radiochromic films, undyed and dyed polyethylene. Preliminary studies show that water calorimeter and dichromate dosimeter are reproducible and sufficiently accurate for electron beam calibration. The estimated overall uncertainty of the measurement is better than 5% at 95% confidence level.

  2. Electron beam injection during active experiments. I - Electromagnetic wave emissions

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Kellogg, P. J.

    1990-01-01

    The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

  3. 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.

  4. Electromagnetic instability in an electron beam-ion channel system

    NASA Astrophysics Data System (ADS)

    Su, D.; Tang, C. J.

    2009-05-01

    The transverse electromagnetic instability in the electron beam-ion channel system is investigated using kinetic theory. The equilibrium distribution function of a relativistic electron beam, which takes into account a strong ion channel effect, is obtained. The linearized Vlasov equation is solved and the dispersion relation of the system is derived by perturbing the equilibrium with a high frequency electromagnetic wave (EMW). Analysis of the dispersion relation shows that the coupling of the electron beam with the transverse high frequency EMW is achieved through the deflection of the beam electrons due to the synergistic effects of the transverse high frequency EMW and transverse betatron oscillation. The numerical calculation finds that a branch of slow wave instability (SWI) with a wide frequency band is excited. The attenuation index of the SWI increases and its frequency band broadens as the normalized beam radii increases. Besides, the SWI will be suppressed as the longitudinal velocity of the electron beam increases to a certain value; meanwhile, a bunch of fast wave instability (FWI) is excited, which is equal to the increase of the relativistic factor. Also both the SWI and the FWI reach maximum when the EMW frequency meets a resonance condition.

  5. Anti-planetward auroral electron beams at Saturn

    NASA Astrophysics Data System (ADS)

    Saur, J.; Mauk, B. H.; Mitchell, D. G.; Krupp, N.; Khurana, K. K.; Livi, S.; Krimigis, S. M.; Newell, P. T.; Williams, D. J.; Brandt, P. C.; Lagg, A.; Roussos, E.; Dougherty, M. K.

    2006-02-01

    Strong discrete aurorae on Earth are excited by electrons, which are accelerated along magnetic field lines towards the planet. Surprisingly, electrons accelerated in the opposite direction have been recently observed. The mechanisms and significance of this anti-earthward acceleration are highly uncertain because only earthward acceleration was traditionally considered, and observations remain limited. It is also unclear whether upward acceleration of the electrons is a necessary part of the auroral process or simply a special feature of Earth's complex space environment. Here we report anti-planetward acceleration of electron beams in Saturn's magnetosphere along field lines that statistically map into regions of aurora. The energy spectrum of these beams is qualitatively similar to the ones observed at Earth, and the energy fluxes in the observed beams are comparable with the energies required to excite Saturn's aurora. These beams, along with the observations at Earth and the barely understood electron beams in Jupiter's magnetosphere, demonstrate that anti-planetward acceleration is a universal feature of aurorae. The energy contained in the beams shows that upward acceleration is an essential part of the overall auroral process.

  6. 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.

  7. Plasma and ion barrier for electron beam spot stability

    SciTech Connect

    Kwan, T.J.T.; Snell, C.M.

    1999-04-01

    The concept of a self-biased target to spatially confine the ions generated by the bombardment of intense electron beams on bremsstrahlung conversion targets has been predicted by computer simulation and further verified by experiments at the Integrated Test Stand for DARHT at Los Alamos National Laboratory. This technical article reports an alternative method of containing the plasmas and ions from the bremsstrahlung conversion target if the energy density of the electron beam is below a certain threshold. With the proposed changes of the electron beam parameters of the second axis of DARHT, the authors are able to show that a thin (0.5 mm) metallic barrier such as pure beryllium, or boron carbide with desirable thermal properties, is sufficiently transparent to the 20 MeV DARHT beam and at the same time able to confine the ions between the target and the barrier foil. The temperature rise in the foil due to energy deposited by the electron beam is expected to be below the melting point of the materials for the first three pulses. More important, they have shown in their time dependent particle-in-cell simulations that the deployment of a barrier situated 1 to 2 cm away from the converter target can achieve the ion confinement needed for the stability of the electron beam spot.

  8. Effects of Electron Beam Irradiation on the Electrospinning of Polyacrylonitrile.

    PubMed

    Jeun, Joon-Pyo; Kim, Hyun-Bin; Oh, Seung-Hwan; Park, Jung-Ki; Kang, Phil-Hyun

    2015-08-01

    Electron beam (e-beam) irradiation of polyacrylonitrile (PAN) was performed to investigate the effects of radiation on the electrospinning process. For this study, polyacrylonitrile powder was subjected to e-beam irradiation with different doses of up to 100 kGy under an N2 atmosphere. Polymer solutions were prepared by dissolving PAN in N,N-dimethyl-formamide (DMF) at a 1:9 ratio by weight. The prepared PAN/DMF solutions showed different colors with different e-beam doses. The resulting structures in solutions contained conjugated C=N bonds, which caused the observed color formation. In addition, the conductivity of the PAN/DMF solution increased with an increase in e-beam irradiation dose. In the DSC spectra of electrospun PAN fibers, the peak temperature of the exothermic reactions was observed to decrease with an increase in the e-beam irradiation strength. PMID:26369176

  9. 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.

  10. Rippled beam free-electron laser amplifier using the axial free-electron laser interaction

    SciTech Connect

    Carlsten, B.E.

    1997-05-01

    A new microwave generation mechanism involving a scalloping annular electron beam is discussed. 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. In this paper, we analyze the ripple motion of the electron beam and derive the dispersion relation describing the exponential growth of the rf mode. We calculate the gain for a nominal design and as a function of beam current and ripple amplitude, and show that power gain on the order of 30 dB/m of interaction is achievable. We additionally demonstrate that, under the right conditions, the interaction is autoresonant. {copyright} {ital 1997 American Institute of Physics.}

  11. 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

  12. Beam by design: Laser manipulation of electrons in modern accelerators

    NASA Astrophysics Data System (ADS)

    Hemsing, Erik; Stupakov, Gennady; Xiang, Dao; Zholents, Alexander

    2014-07-01

    Accelerator-based light sources such as storage rings and free-electron lasers use relativistic electron beams to produce intense radiation over a wide spectral range for fundamental research in physics, chemistry, materials science, biology, and medicine. More than a dozen such sources operate worldwide, and new sources are being built to deliver radiation that meets with the ever-increasing sophistication and depth of new research. Even so, conventional accelerator techniques often cannot keep pace with new demands and, thus, new approaches continue to emerge. In this article, a variety of recently developed and promising techniques that rely on lasers to manipulate and rearrange the electron distribution in order to tailor the properties of the radiation are reviewed. Basic theories of electron-laser interactions, techniques to create microstructures and nanostructures in electron beams, and techniques to produce radiation with customizable waveforms are reviewed. An overview of laser-based techniques for the generation of fully coherent x rays, mode-locked x-ray pulse trains, light with orbital angular momentum, and attosecond or even zeptosecond long coherent pulses in free-electron lasers is presented. Several methods to generate femtosecond pulses in storage rings are also discussed. Additionally, various schemes designed to enhance the performance of light sources through precision beam preparation including beam conditioning, laser heating, emittance exchange, and various laser-based diagnostics are described. Together these techniques represent a new emerging concept of "beam by design" in modern accelerators, which is the primary focus of this article.

  13. Upgrade of the electron beam ion trap in Shanghai

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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 10-10 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 × 10-4. 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 Xe53+, 54+ has been produced and the characterization of current density is estimated from the measured electron beam width.

  14. Particle Simulations for Electron Beam-Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Zhou, Guo-cheng; G, Zhou C.; Li, Yang; Cao, Jin-bin; J, Cao B.; Wang, Xue-yi; X, Wang Y.

    1998-12-01

    The computer simulations of high-frequency instabilities excited by the high density electron beam and their nonlinear effect are presented. One-dimensional electromagnetic particle simulations are performed with different values of the electron beam-to-plasma density ratio. The results show that for the high electron beam-to-background plasma density ratio, all the Langmuir waves and two electromagnetic waves with left-hand and right-hand circular polarizations (i.e., the "L-O mode" and the "R-X mode") propagating parallel to the magnetic field can be generated and the maximum values of wave electric fields are nearly the same. The electron beam and background plasma are diffused and a part of energetic background electrons are obviously accelerated by the wave-particle interactions. The heating of the beam and background plasma is mainly due to the electrostatic (Langmuir) wave-particle interactions, but the accelerations of a part of energetic background electrons may be mainly due to the electromagnetic wave-particle interactions.

  15. 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.

  16. Silicon nanocrystal growth under irradiation of electron beam

    PubMed Central

    Huang, Wei-Qi; Liu, Shi-Rong; Huang, Zhong-Mei; Dong, Tai-Ge; Wang, Gang; Qin, Cao-Jian

    2015-01-01

    In our experiment, it was observed that silicon nanocrystal rapidly grows with irradiation of electron beam on amorphous silicon film prepared by pulsed laser deposition, and shape of silicon nanocrystal is usually sphere in smaller nanoscale with less exposure time under electron beam, in which the quantum dots are prepared in nanoscale near 3 nm. In the electron interaction process, it was investigated that the various crystals structures in different orientations occur in the same time and the condensed structures of silicon nanocrystal are changed with different impurity atoms in silicon film. PMID:26608069

  17. 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

  18. Continuum models of focused electron beam induced processing

    PubMed Central

    Lobo, Charlene; Friedli, Vinzenz; Szkudlarek, Aleksandra; Utke, Ivo

    2015-01-01

    Summary Focused electron beam induced processing (FEBIP) is a suite of direct-write, high resolution techniques that enable fabrication and editing of nanostructured materials inside scanning electron microscopes and other focused electron beam (FEB) systems. Here we detail continuum techniques that are used to model FEBIP, and release software that can be used to simulate a wide range of processes reported in the FEBIP literature. These include: (i) etching and deposition performed using precursors that interact with a surface through physisorption and activated chemisorption, (ii) gas mixtures used to perform simultaneous focused electron beam induced etching and deposition (FEBIE and FEBID), and (iii) etch processes that proceed through multiple reaction pathways and generate a number of reaction products at the substrate surface. We also review and release software for Monte Carlo modeling of the precursor gas flux which is needed as an input parameter for continuum FEBIP models. PMID:26425405

  19. Spatial dose distribution in polymer pipes exposed to electron beam

    NASA Astrophysics Data System (ADS)

    Ponomarev, Alexander V.

    2016-01-01

    Non-uniform distribution of absorbed dose in cross-section of any polymeric pipe is caused by non-uniform thickness of polymer layer penetrated by unidirectional electron beam. The special computer program was created for a prompt estimation of dose non-uniformity in pipes subjected to an irradiation by 1-10 MeV electron beam. Irrespective of electron beam energy, the local doses absorbed in the bulk of a material can be calculated on the basis of the universal correlations offered in the work. Incomplete deceleration of electrons in shallow layers of a polymer was taken into account. Possibilities for wide variation of pipe sizes, polymer properties and irradiation modes were provided by the algorithm. Both the unilateral and multilateral irradiation can be simulated.

  20. Disruption of Particle Detector Electronics by Beam Generated EMI

    SciTech Connect

    Bower, G.; Sugimoto, Y.; Sinev, N.; Arnold, R.; Woods, M.; /SLAC

    2007-06-27

    The possibility that radio frequency beam generated electromagnetic interference (EMI) could disrupt the operation of particle detector electronics has been of some concern since the inception of short pulse electron colliders more than 30 years ago [1]. Some instances have been reported where this may have occurred but convincing evidence has not been available. This possibility is of concern for the International Linear Collider (ILC). We have conducted test beam studies demonstrating that electronics disruption does occur using the vertex detector electronics (VXD) from the SLD detector which took data at the SLC at SLAC. We present the results of those tests, and we describe the need for EMI standards for beam and detector instrumentation in the IR region at the ILC.

  1. 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.

  2. Electron beam charge diagnostics for laser plasma accelerators

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Smith, A.; Rodgers, D.; Donahue, R.; Byrne, W.; Leemans, W. P.

    2011-06-01

    A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). First, a scintillating screen (Lanex) was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT) for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160pC/mm2 and 0.4pC/(psmm2), respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within ±8%, showing that they all can provide accurate charge measurements for LPAs.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

    2005-03-01

    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

  8. Electron beam chemistry produces high purity metals

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; May, C. E.; Marsik, S. J.; Lad, R. A.

    1972-01-01

    Application of radiation chemistry for deposition of metals by irradiation of aqueous solutions with high energy electrons is presented. Design of reaction vessel for irradiation of solution is illustrated. Features of radiochemical technique and procedures followed are described.

  9. 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.

  10. 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.

  11. Electron-beam-activated zinc selenide and diamond switches

    NASA Astrophysics Data System (ADS)

    Schoenbach, Karl H.; Kennedy, Mark R.; Joshi, Ravindra P.; Brinkmann, Ralf P.; Ho, Ping-Tong

    1992-05-01

    Zinc Selenide, in polycrystalline and single crystal form, and chemical vapor deposition (CVD) grown diamond films were studied with respect to their application as materials for electron-beam activated switches. The hold-off fields of the three materials were found to exceed that of semi-insulating gallium arsenide by at least an order of magnitude. Highest hold-off fields for pulsed voltage operation were recorded for diamond at 1.8 MV/cm. The electron-beam induced conductance in the 1 mm thick single crystal zinc selenide switches reached values of 0.5 (Ωcm2)-1 with an electron-beam current density of 20 mA/cm2 at electron-energies of 150 keV. This corresponds to an electron-beam induced reduction of switch resistance from 108 Ω to 2 Ω per square centimeter. The dominant carrier loss mechanism in the single crystal zinc selenide switch was found to be direct recombination of electron-hole pairs. In this material, the current, after electron-beam turn-off, decays hyperbolically with 90% to 10% falitimes in the range of hundreds of nanoseconds. The electron-beam induced conductivity in CVD grown diamond films of 1 micrometer thickness is due to the subnanosecond carrier lifetime less than three orders lower than that of single crystal zinc selenide. Both materials, single crystal zinc selenide and diamond, showed a lock-on effect in current. For diamond it could be demonstrated, as before for gaffium arsenide, that this effect can be suppressed by proper choice of contacts.

  12. 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.

  13. 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.

  14. Positron beam position measurement for a beam containing both positrons and electrons

    SciTech Connect

    Sereno, N.S.; Fuja, R.

    1996-08-01

    Positron beam position measurement for the Advanced Photon Source (APS) linac beam is affected by the presence of electrons that are also captured and accelerated along with the positrons. This paper presents a method of measuring positron position in a beam consisting of alternating bunches of positrons and electrons. The method is based on Fourier analysis of a stripline signal at the bunching and first harmonic frequencies. In the presence of a mixed species beam, a certain linear combination of bunching and first harmonic signals depends only on the position and charge of one specie of particle. A formula is derived for the stripline signal at all harmonics of the bunching frequency and is used to compute expected signal power at the bunching and first harmonic frequencies for typical electron and positron bunch charges. The stripline is calibrated by measuring the signal power content at the bunching and first harmonic frequencies for a single species beam. A circuit is presented that will be used with an APS positron linac stripline beam position monitor to detect the bunching and first harmonic signals for a beam of positrons and electrons.

  15. 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.

  16. Two-screen single-shot electron spectrometer for laser wakefield accelerated electron beams.

    PubMed

    Soloviev, A A; Starodubtsev, M V; Burdonov, K F; Kostyukov, I Yu; Nerush, E N; Shaykin, A A; Khazanov, E A

    2011-04-01

    The laser wakefield acceleration electron beams can essentially deviate from the axis of the system, which distinguishes them greatly from beams of conventional accelerators. In case of energy measurements by means of a permanent-magnet electron spectrometer, the deviation angle can affect accuracy, especially for high energies. A two-screen single-shot electron spectrometer that correctly allows for variations of the angle of entry is considered. The spectrometer design enables enhancing accuracy of measuring narrow electron beams significantly as compared to a one-screen spectrometer with analogous magnetic field, size, and angular acceptance. PMID:21529002

  17. 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

  18. High energy density plasma science with an ultrarelativistic electron beam

    NASA Astrophysics Data System (ADS)

    Joshi, C.; Blue, B.; Clayton, C. E.; Dodd, E.; Huang, C.; Marsh, K. A.; Mori, W. B.; Wang, S.; Hogan, M. J.; O'Connell, C.; Siemann, R.; Watz, D.; Muggli, P.; Katsouleas, T.; Lee, S.

    2002-05-01

    An intense, high-energy electron or positron beam can have focused intensities rivaling those of today's most powerful laser beams. For example, the 5 ps (full-width, half-maximum), 50 GeV beam at the Stanford Linear Accelerator Center (SLAC) at 1 kA and focused to a 3 micron rms spot size gives intensities of >1020 W/cm-2 at a repetition rate of >10 Hz. Unlike a ps or fs laser pulse which interacts with the surface of a solid target, the particle beam can readily tunnel through tens of cm of steel. However, the same particle beam can be manipulated quite effectively by a plasma that is a million times less dense than air! This is because of the incredibly strong collective fields induced in the plasma by the Coulomb force of the beam. The collective fields in turn react back onto the beam leading to many clearly observable phenomena. The beam paraticles can be: (1) Deflected leading to focusing, defocusing, or even steering of the beam; (2) undulated causing the emission of spontaneous betatron x-ray radiation and; (3) accelerated or decelerated by the plasma fields. Using the 28.5 GeV electron beam from the SLAC linac a series of experiments have been carried out that demonstrate clearly many of the above mentioned effects. The results can be compared with theoretical predictions and with two-dimensional and three-dimensional, one-to-one, particle-in-cell code simulations. These phenomena may have practical applications in future technologies including optical elements in particle beam lines, synchrotron light sources, and ultrahigh gradient accelerators.

  19. Diocotron instability in annular relativistic electron beams

    SciTech Connect

    Jones, M.E.; Mostrom, M.A.

    1981-06-01

    A dispersion relation which includes finite axial wavevectors, k, is derived in the rest frame of the beam where the instability is assumed to be electrostatic. The dispersion relation is obtained in the lab frame by a Lorentz transformation. The instability is found to have a finite k bandwidth with the most unstable mode occurring at knot =0. The growth rate for the most unstable mode is found to be reduced by approximately 1/..gamma../sup 2/ from the nonrelativistic result while the real frequency of this mode remains virtually unchanged. The effects of finite v/sub z/ shear, which are left out of the analysis, are estimated and discussed.

  20. 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.

  1. 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.

  2. Gamma-ray generation using laser-accelerated electron beam

    NASA Astrophysics Data System (ADS)

    Park, Seong Hee; Lee, Ho-Hyung; Lee, Kitae; Cha, Yong-Ho; Lee, Ji-Young; Kim, Kyung-Nam; Jeong, Young Uk

    2011-06-01

    A compact gamma-ray source using laser-accelerated electron beam is being under development at KAERI for nuclear applications, such as, radiography, nuclear activation, photonuclear reaction, and so on. One of two different schemes, Bremsstrahlung radiation and Compton backscattering, may be selected depending on the required specification of photons and/or the energy of electron beams. Compton backscattered gamma-ray source is tunable and quasimonochromatic and requires electron beams with its energy of higher than 100 MeV to produced MeV photons. Bremsstrahlung radiation can generate high energy photons with 20 - 30 MeV electron beams, but its spectrum is continuous. As we know, laser accelerators are good for compact size due to localized shielding at the expense of low average flux, while linear RF accelerators are good for high average flux. We present the design issues for a compact gamma-ray source at KAERI, via either Bremsstrahlung radiation or Compton backscattering, using laser accelerated electron beams for the potential nuclear applications.

  3. Detoxification of the veterinary antibiotic chloramphenicol using electron beam irradiation.

    PubMed

    Cho, Jae Young; Chung, Byung Yeoup; Hwang, Seon Ah

    2015-07-01

    Electron beam irradiation has shown potential as an alternative process for the treatment of industrial effluents that contain toxic organic chemicals. This study investigated the effectiveness of electron beam in degrading chloramphenicol (CAP) in aqueous solution. The degradation efficiency was 32.4% at 1 kGy, 86.9% at 5 kGy, and 100% at 10 kGy. The total organic carbon (TOC) of CAP in aqueous solution declined 4.6% at 1 kGy, 12.1% at 5 kGy, and 17.1% at 10 kGy of irradiation with electron beam. The CAP degradation products after irradiation were CAP1 ([M + H] m/z 307.1), CAP2 ([M + H] m/z 291.1), and CAP3 ([M + H] m/z 321.1). The degradation products were tested for microbial toxicity against Escherichia coli, Pseudomonas putida, and Bacillus subtilis and did not show any toxic antimicrobial effects caused by the CAP degradation products after irradiation with electron beam. The results of this study suggest that electron beam irradiation is the best technology for the comprehensive treatment of veterinary antibiotics at wastewater treatment plants. PMID:25616384

  4. 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.

  5. Effect of secondary ions on the electron beam optics in the Recycler Electron Cooler

    SciTech Connect

    Shemyakin, A.; Prost, L.; Saewert, G.

    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.

  6. Measuring the emittance of the DARHT-II electron beam

    NASA Astrophysics Data System (ADS)

    Ekdahl, Carl; Bartsch, Richard; Custer, Dan; Ridlon, Rae; Rose, Evan; Eylon, Shmuel; Broste, William; Johnson, Jefferey

    2001-10-01

    The DARHT-II linear induction accelerator (LIA) is being built for radiography of large-scale, explosively-driven hydrodynamics experiments. When fully operational, DARHT-II will have an electron beam current of 2-kA and a beam energy of 18 MeV. The two-microsecond beam pulse will be chopped into four short pulses for time resolution of hydrodynamic motion. A small radiographic spot size is a requirement for DARHT-II. The DARHT-II LIA design emphasizes low beam emittance to reduce the spot size. Measuring the emittance of a high-power, 2-micro-sec beam presents special challenges, and we will discuss two different approaches. In the first technique a fast solenoid is employed to focus the beam onto an imaging screen in 120 ns to prevent overheating of the screen and consequent beam disruption by evolved gas/plasma/ions. The fast-focus coil must produce a 1 kG field over an effective length of 50 cm. The design and testing of this coil and its pulsed-power driver will be presented. The second technique uses non-invasive diamagnetic loop measurements, from which the beam radius can be inferred, at several locations. A beam envelope code is then used to find the most likely emittance that fits the data. In this presentation these methods are compared with respect to expected uncertainties, and the resulting accuracy of emittance determination.

  7. Electron beam assisted field evaporation of insulating nanowires/tubes

    NASA Astrophysics Data System (ADS)

    Blanchard, N. P.; Niguès, A.; Choueib, M.; Perisanu, S.; Ayari, A.; Poncharal, P.; Purcell, S. T.; Siria, A.; Vincent, P.

    2015-05-01

    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. Quasimonoenergetic electron beams from laser wakefield acceleration in pure nitrogen

    SciTech Connect

    Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.

    2012-02-13

    Quasimonoenergetic electron beams with maximum energy >0.5 GeV and 2 mrad divergence have been generated in pure nitrogen gas via wakefield acceleration with 80 TW, 30 fs laser pulses. Long low energy tail features were typically observed due to continuous ionization injection. The measured peak electron energy decreased with the plasma density, agreeing with the predicted scaling for electrons. The experiments showed a threshold electron density of 3x10{sup 18}cm{sup -3} for self-trapping. Our experiments suggest that pure Nitrogen is a potential candidate gas to achieve GeV monoenergetic electrons using the ionization induced injection scheme for laser wakefield acceleration.

  9. 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.

  10. 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

  11. Time-resolved tomographic images of a relativistic electron beam

    SciTech Connect

    Koehler, H.A.; Jacoby, B.A.; Nelson, M.

    1984-07-01

    We obtained a sequential series of time-resolved tomographic two-dimensional images of a 4.5-MeV, 6-kA, 30-ns electron beam. Three linear fiber-optic arrays of 30 or 60 fibers each were positioned around the beam axis at 0/sup 0/, 61/sup 0/, and 117/sup 0/. The beam interacting with nitrogen at 20 Torr emitted light that was focused onto the fiber arrays and transmitted to a streak camera where the data were recorded on film. The film was digitized, and two-dimensional images were reconstructed using the maximum-entropy tomographic technique. These images were then combined to produce an ultra-high-speed movie of the electron-beam pulse.

  12. Electron beam-assisted healing of nanopores in magnesium alloys

    NASA Astrophysics Data System (ADS)

    Zheng, He; Liu, Yu; Cao, Fan; Wu, Shujing; Jia, Shuangfeng; Cao, Ajing; Zhao, Dongshan; Wang, Jianbo

    2013-05-01

    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.

  13. Electrical measurement techniques for pulsed high current electron beams

    SciTech Connect

    Struve, K.W.

    1986-04-01

    The advent of high current (1 to 100 kA), moderate energy (>10 MeV), short pulse (1 to 100 ns) electron accelerators used for charged particle beam research has motivated a need to complement standard diagnostics with development of new diagnostic techniques to measure electron beam parameters. A brief survey is given of the diagnostics for measuring beam current, position, size, energy, and emittance. While a broad scope of diagnostics will be discussed, this survey will emphasize diagnostics used on the Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA). Focus is placed on diagnostics measuring beam current, position and size. Among the diagnostics discussed are resistive wall current monitors, B/sub theta/ loops, Rogowski coils, Faraday cups, and x-ray wire diagnostics. Operation at higher current levels also increases radiation and electromagnetic pulse interference. These difficulties and methods for circumventing them are also discussed.

  14. Small field electron beam dosimetry using MOSFET detector.

    PubMed

    Amin, Md Nurul; Heaton, Robert; Norrlinger, Bern; Islam, Mohammad K

    2011-01-01

    The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth-dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. Since modern radiotherapy departments are becoming filmless in favor of electronic imaging, an alternate and readily available clinical dosimeter needs to be explored. We have studied the performance of MOSFET as a relative dosimeter in small field electron beams. The reproducibility, linearity and sensitivity of a high-sensitivity microMOSFET were investigated for clinical electron beams. In addition, the percent depth doses, output factors and profiles have been measured in a water tank with MOSFET and compared with those measured by an ion chamber for a range of field sizes from 1 cm diameter to 10 cm × 10 cm for 6, 12, 16 and 20 MeV beams. Similar comparative measurements were also per-formed with MOSFET and films in solid water phantom. The MOSFET sensitivity was found to be practically constant over the range of field sizes investigated. The dose response was found to be linear and reproducible (within ± 1% for 100 cGy). An excellent agreement was observed among the central axis depth dose curves measured using MOSFET, film and ion chamber. The output factors measured with MOSFET for small fields agreed to within 3% with those measured by film dosimetry. Overall results indicate that MOSFET can be utilized to perform dosimetry for small field electron beam. PMID:21330970

  15. Resurrection of beam conditioning for free electron lasers

    SciTech Connect

    Xie, Ming

    2003-02-17

    Recently Emma and Stupakov identified a fatal flaw in a Free Electron Laser (FEL) beam conditioning scheme. They showed that the conditioning is always accompanied by a projected transverse emittance growth that is so large as to make the beam conditioning completely impractical for short wavelength FELs. Furthermore, they provided a general proof along with evidence of computer simulation and reached a conclusion that any beam conditioner, regardless of the method, would suffer from the same constraints and limitations. In this paper, the author proposes an easy surgical removal of the fatal flaw by making a critical yet simple modification to the very scheme analyzed, thus resurrect the beam conditioning for short wavelength FELs. More generally, the also explain why a general search for removing have failed, why the concept and definition of beam conditioning.

  16. Observations of underdense plasma lens focusing of relativistic electron beams

    SciTech Connect

    Thompson, M.C.; Badakov, H.; Rosenzweig, J.B.; Travish, G.; Fliller, R.; Kazakevich, G.M.; Piot, P.; Santucci, J.; Li, J.; Tikhoplav, R.; /Rochester U.

    2007-06-01

    Focusing of a 15 MeV, 19 nC electron bunch by an underdense plasma lens operated just beyond the threshold of the underdense condition has been demonstrated in experiments at the Fermilab NICADD Photoinjector Laboratory (FNPL). The strong 1.9 cm focal-length plasma-lens focused both transverse directions simultaneously and reduced the minimum area of the beam spot by a factor of 23. Analysis of the beam-envelope evolution observed near the beam waist shows that the spherical aberrations of this underdense lens are lower than those of an overdense plasma lens, as predicted by theory. Correlations between the beam charge and the properties of the beam focus corroborate this conclusion.

  17. 6D electron beam diagnostics at SPARC_LAB

    NASA Astrophysics Data System (ADS)

    Cianchi, A.; Anania, M. P.; Bacci, A.; Bellaveglia, Marco; Castellano, Michele; Chiadroni, Enrica; Di Giovenale, Domenico; Di Pirro, Giampiero; Ferrario, Massimo; Innocenti, Luca; Mostacci, Andrea; Pompili, Riccardo; Rossi, A. R.; Shpakov, V.; Vaccarezza, Cristina; Villa, Fabio

    2015-05-01

    To create very short electron bunches or comb-like beams, able to drive a SASE-FEL, to produce THz radiation, or to drive a plasma beam driven accelerator is needed advanced phase space manipulation. The characterization of the 6D phase space is of paramount importance in order to verify that the beam parameters fulfill the expectation. At SPARCLAB we have integrated several longitudinal and transverse beam diagnostics for single bunch or for a train of comb-like bunches at THz repetition rate. Longitudinal diagnostic is based on RF deflecting cavity and a dispersive element. Quadrupole scan technique is used to measure the transverse emittance in single bunch mode or in conjunction respectively with a dipole, to separate beams of different energy, and RF deflector, to discriminates bunches with different time of arrival.

  18. 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.

  19. Electron Beam Welding of Duplex Steels with using Heat Treatment

    NASA Astrophysics Data System (ADS)

    Schwarz, Ladislav; Vrtochová, Tatiana; Ulrich, Koloman

    2010-01-01

    This contribution presents characteristics, metallurgy and weldability of duplex steels with using concentrated energy source. The first part of the article describes metallurgy of duplex steels and the influence of nitrogen on their solidification. The second part focuses on weldability of duplex steels with using electron beam aimed on acceptable structure and corrosion resistance performed by multiple runs of defocused beam over the penetration weld.

  20. 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.

  1. 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.

  2. 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.

  3. Divergence of laser-driven relativistic electron beams

    SciTech Connect

    Debayle, A.; Honrubia, J. J.; D'Humieres, E.; Tikhonchuk, V. T.

    2010-09-15

    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.

  4. 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. PMID:21230194

  5. High Energy Density Science with Ultrarelativistic Electron Beams

    NASA Astrophysics Data System (ADS)

    Joshi, Chan

    2001-10-01

    An intense, high-energy electron or positron beam can have focused intensities rivaling those of today's most powerful lasers. For example, the 5 ps (FWHM), 50 GeV beam at the Stanford Linear Accelerator Center at 1 kA and focused to a 3 micron rms spot size gives intensities of > 10^20 W/cm^2 at a repetition rate of 10 Hz. Unlike a ps or fs laser pulse, the particle beam can readily bore through several mm of steel due to the rigidity of its flux component. However, the same particle beam can be manipulated quite strongly by a plasma that is a million times less dense than air! This is because of the incredibly strong collective fields induced in the plasma by the Coulomb force of the beam. The collective fields in turn react back onto the beam leading to many clearly-observable phenomena. The beam can be: (1) deflected leading focusing, defocusing, or even steering of the beam; (2) undulated causing the emission of spontaneous betatron x-ray radiation and; (3) accelerated or de-accelerated by the plasma fields. Using the 28.5 GeV electron and positron beams from the SLAC linac we have carried out a series of experiments that demonstrate clearly the above mentioned effects. The results are compared with theoretical predictions and 3D, one-to-one PIC code simulations using the code OSIRIS. These phenomena may have practical application in future technologies including optical elements in particle beam lines, synchrotron light sources, and ultra-high gradient accelerators.

  6. Direct write electron beam lithography: a historical overview

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Hans C.

    2010-09-01

    Maskless pattern generation capability in combination with practically limitless resolution made probe-forming electron beam systems attractive tools in the semiconductor fabrication process. However, serial exposure of pattern elements with a scanning beam is a slow process and throughput presented a key challenge in electron beam lithography from the beginning. To meet this challenge imaging concepts with increasing exposure efficiency have been developed projecting ever larger number of pixels in parallel. This evolution started in the 1960s with the SEM-type Gaussian beam systems writing one pixel at a time directly on wafers. During the 1970s IBM pioneered the concept of shaped beams containing multiple pixels which led to higher throughput and an early success of e-beam direct write (EBDW) in large scale manufacturing of semiconductor chips. EBDW in a mix-and match approach with optical lithography provided unique flexibility in part number management and cycle time reduction and proved extremely cost effective in IBM's Quick-Turn-Around-Time (QTAT) facilities. But shaped beams did not keep pace with Moore's law because of limitations imposed by the physics of charged particles: Coulomb interactions between beam electrons cause image blur and consequently limit beam current and throughput. A new technology approach was needed. Physically separating beam electrons into multiple beamlets to reduce Coulomb interaction led to the development of massively parallel projection of pixels. Electron projection lithography (EPL) - a mask based imaging technique emulating optical steppers - was pursued during the 1990s by Bell Labs with SCALPEL and by IBM with PREVAIL in partnership with Nikon. In 2003 Nikon shipped the first NCR-EB1A e-beam stepper based on the PREVAIL technology to Selete. It exposed pattern segments containing 10 million pixels in single shot and represented the first successful demonstration of massively parallel pixel projection. However the window

  7. 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.

  8. Beam injection improvement for electron cyclotron resonance charge breeders

    SciTech Connect

    Lamy, T.; Angot, J.; Sortais, P.; Thuillier, T.

    2012-02-15

    The injection of a 1+ beam into an electron cyclotron resonance (ECR) charge breeder is classically performed through a grounded tube placed on its axis at the injection side. This tube presents various disadvantages for the operation of an ECR charge breeder. First experiments without a grounded tube show a better use of the microwave power and a better charge breeding efficiency. The optical acceptance of the charge breeder without decelerating tube allows the injection of high intensity 1+ ion beams at high energy, allowing metals sputtering inside the ion source. The use of this method for refractory metallic ion beams production is evaluated.

  9. 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.

  10. Characterization of a low-voltage electron beam

    NASA Astrophysics Data System (ADS)

    Berejka, Anthony J.

    2004-09-01

    Growing interests in low-voltage electron beam (EB) processing in areas that may require regulatory compliance, such as the curing of inks and coatings for food packaging materials and in the surface disinfection of medicinal and food containers, lead to the characterization of a low-voltage EB by two methods: a widely used thin radiochromic film and a film strip made on a continuous basis with an alanine coating. Using a laboratory unit, beam currents and voltages were varied and then optical density and alanine/matrix ratios were, respectively, determined. No inferences as to "dose" were made. The radiochromic film was found to be insensitive to slight changes at low beam currents and to show considerable divergence and a broadening in response as current was increased across a meaningful range at the three applied beam voltages of 80, 100 and 120 kV. The electron paramagnetic resonance (EPR) increase in response of the alanine coated film taken as a ratio to an internal reference material within the test instrument itself was shown to have a linear response with respect to beam current and no divergence as current increased. The use of an alanine coating of thickness greater than that of the extrapolated range of the electron penetration offers a method for the characterization of the output of such very low-voltage beams.

  11. 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.

  12. 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.

  13. 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.

  14. Heavy ion beam-ionosphere interactions - Electron acceleration

    NASA Technical Reports Server (NTRS)

    Kaufmann, R. L.; Arnoldy, R. L.; Moore, T. E.; Kintner, P. M.; Cahill, L. J., Jr.

    1985-01-01

    Moore et al. (1982) described a number of unexpected effects which were observed during the first Argon Release Controlled Study (ARCS 1, or rocket flight 29:014). The present paper provides a description of detailed analyses of the interaction of the argon beam with the ionosphere. An important feature of the considered test was that all detectors and the Ar(+) gun remained attached to the rocket throughout the flight. It is pointed out that the most dramatic effect of ion gun operation on ARCS 1 involved large changes in the fluxes of electrons with energies below about 600 eV. The observations are discussed, taking into account the distribution functions, azimuth dependence, and electron and ion trajectories. Attention is given to the perpendicular ion beam, the parallel ion beam, the acceleration of downgoing and upgoing electrons, and aspects of wave generation.

  15. Imaging nanometer-scale beamlets arrays of relativistic electron beams

    SciTech Connect

    Li, R. K.; To, H.; Musumeci, P.

    2012-12-21

    In this paper we study the evolution of nanometer scale transverse density modulation of a high brightness electron beam through a drift and simple focusing channel. With the help of particle tracking simulations we analyze the effects of space charge forces, emittance and energy spread on the feasibility of recovering an initial nm-scale transverse modulation after transport through a magnifying optical system. These studies are relevant for applications such as time-resolved MeV transmission electron microscopy and in the high brightness electron beam community due to the recent developments of nano-structured cathodes and due to the possibility of taking advantage of nm-structures in the beam for coherent radiation generation.

  16. Heavy ion beam-ionosphere interactions - Electron acceleration

    NASA Astrophysics Data System (ADS)

    Kaufmann, R. L.; Arnoldy, R. L.; Moore, T. E.; Kintner, P. M.; Cahill, L. J., Jr.

    1985-10-01

    Moore et al. (1982) described a number of unexpected effects which were observed during the first Argon Release Controlled Study (ARCS 1, or rocket flight 29:014). The present paper provides a description of detailed analyses of the interaction of the argon beam with the ionosphere. An important feature of the considered test was that all detectors and the Ar(+) gun remained attached to the rocket throughout the flight. It is pointed out that the most dramatic effect of ion gun operation on ARCS 1 involved large changes in the fluxes of electrons with energies below about 600 eV. The observations are discussed, taking into account the distribution functions, azimuth dependence, and electron and ion trajectories. Attention is given to the perpendicular ion beam, the parallel ion beam, the acceleration of downgoing and upgoing electrons, and aspects of wave generation.

  17. Image tube. [deriving electron beam replica of image

    NASA Technical Reports Server (NTRS)

    Hallam, K. L.; Johnson, C. B. (Inventor)

    1974-01-01

    An optical image is projected onto a planar surface of a photocathode that derives an electron beam replica of the image. A target electrode displaced relative to the photocathode so that it does not obstruct the optical image includes a planar surface for receiving and deriving an accurate replica of the electron beam image. The two planar surfaces are parallel. The electron beam image is focused on the target electrode by providing throughout a region that extends between the planar surfaces of the photocathode and receiving electrode, constant homogeneous dc electric and magnetic fields. The electric field extends in a direction perpendicular to the planar surfaces while the magnetic field extends along a straight line that intersects the photocathode and target electrode at an acute angle.

  18. 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.

  19. Silicon nitride films deposited with an electron beam created plasma

    NASA Astrophysics Data System (ADS)

    Bishop, D. C.; Emery, K. A.; Rocca, J. J.; Thompson, L. R.; Zamani, H.; Collins, G. J.

    1984-03-01

    The electron beam assisted chemical vapor deposition (EBCVD) of silicon nitride films using NH3, N2, and SiH4 as the reactant gases is reported. The films have been deposited on aluminum, SiO2, and polysilicon film substrates as well as on crystalline silicon substrates. The range of experimental conditions under which silicon nitrides have been deposited includes substrate temperatures from 50 to 400 C, electron beam currents of 2-40 mA, electron beam energies of 1-5 keV, total ambient pressures of 0.1-0.4 Torr, and NH3/SiH4 mass flow ratios of 1-80. The physical, electrical, and chemical properties of the EBCVD films are discussed.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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%.

  7. 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.

  8. 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.

  9. 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.

  10. Population inversions in ablation plasmas generated by intense electron beams

    NASA Astrophysics Data System (ADS)

    Gilgenbach, R. M.; Kammash, T.; Brake, M. L.

    1988-11-01

    Experiments during the past three years have concerned the generation and spectroscopic study of electron beam-driven carbon plasmas in order to explore the production of optical and ultraviolet radiation from nonequilibrium populations. The output of MELBA (Michigan Electron Long Beam Accelerator), has been connected to an electron beam diode consisting of an aluminum (or brass) cathode stalk and a carbon anode. Magnetic field coils have been designed, procured, and utilized to focus the electron beam. A side viewing port permitted spectroscopic diagnostics to view across the surface of the anode. Spectroscopic diagnosis has been performed using a 1 m spectrograph capable of operation from the vacuum ultraviolet through the visible. This spectrograph is coupled to a 1024 channel optical multichannel analyzer. Spectra taken during the initial 400 ns period of the e-beam pulse showed a low effective charge plasma with primarily molecular components (C2, CH) as well as atomic hydrogen and singly ionized carbon (CII). When the generator pulse was crowbarred after the first 400 ns, the spectra revealed a continuation of the low charge state plasma.

  11. 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.

  12. 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.

  13. Nonlinear transmission line based electron beam driver

    NASA Astrophysics Data System (ADS)

    French, David M.; Hoff, Brad W.; Tang, Wilkin; Heidger, Susan; Allen-Flowers, Jordan; Shiffler, Don

    2012-12-01

    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.

  14. Nonlinear transmission line based electron beam driver.

    PubMed

    French, David M; Hoff, Brad W; Tang, Wilkin; Heidger, Susan; Allen-Flowers, Jordan; Shiffler, Don

    2012-12-01

    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. PMID:23277977

  15. 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.

  16. Ignition of organic explosives by an electron beam

    NASA Astrophysics Data System (ADS)

    Ivanov, Georgy A.; Khaneft, Alexander V.

    2015-01-01

    A numerical simulation of the ignition of organic explosives (PETN, HMX, RDX, TATB) with an electron beam was performed. A criterion for the ignition of energetic materials with a melting point below the temperature of ignition is obtained. The results of numerical calculations of the critical energy density of the electron beam are consistent with the criterion of ignition. Calculations of the critical energy density of PETN ignition in good agreement with the experiment. The most sensitive is PETN and the most heat-resistant is TATB.

  17. 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.

  18. Electron beam weld development on a Filter Pack Assembly

    NASA Astrophysics Data System (ADS)

    Dereskiewicz, J. P.

    1994-06-01

    A continuous electron beam welding procedure was developed to replace the manual gas tungsten arc welding procedure on the Filter Pack Assembly. A statistical study was used to evaluate the feasibility of electron beam welding 6061-T6 aluminum covers to A356 cast weldments throughout the joint tolerance range specified on product drawings. Peak temperature exposures were not high enough to degrade the heat sensitive electrical components inside the cast weldment. Actual weldments with alodine coating on the weld joint area were successfully cleaned using a nonmetallic fiberglass brush cleaning method.

  19. Characteristics of an electron-beam rocket pellet accelerator

    SciTech Connect

    Tsai, C.C.; Foster, C.A.; Schechter, D.E.

    1989-01-01

    An electron-beam rocket pellet accelerator has been designed, built, assembled, and tested as a proof-of-principle (POP) apparatus. The main goal of accelerators based on this concept is to use intense electron-beam heating and ablation of a hydrogen propellant stick to accelerate deuterium and/or tritium pellets to ultrahigh speeds (10 to 20 km/s) for plasma fueling of next-generation fusion devices such as the International Thermonuclear Engineering Reactor (ITER). The POP apparatus is described and initial results of pellet acceleration experiments are presented. Conceptual ultrahigh-speed pellet accelerators are discussed. 14 refs., 8 figs.

  20. 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.

  1. 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.

  2. Field Emitter Magnetic Sensor with Steered Focused Electron Beam

    NASA Astrophysics Data System (ADS)

    Nicolaescu, Dan; Filip, Valeriu; Itoh, Junji

    2001-04-01

    A novel field emission magnetic sensor is proposed and its operation is theoretically analyzed. The sensor comprises a dual-gate wedge field emitter with a split gate having the double role of focusing and steering the electron beam. The electron beam deflection due to the Lorentz force is compensated by appropriate potentials applied to this electrode. The modeling results have been obtained using the Simion 3D 7.0 software package. The device has high sensitivity and its operation is not influenced by fluctuations in the emission current. Arrangements of mutually normal wedge emitters can be used for two-dimensional magnetic field sensing.

  3. 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.

  4. 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.

  5. 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%.

  6. 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.

  7. New possibilities for beam-beam and space-charge compensation: MCP gun and electron columns

    SciTech Connect

    Shiltsev, V.; /Fermilab

    2007-06-01

    We propose to use microchannel plate (MCP) as a gigantic quantum efficiency photo-cathode in electron guns. Another proposal is to use electron columns formed by ionization electrons in a longitudinal magnetic field for compensation of space charge effects in high intensity proton synchrotrons. Strong magnetic field is to assure that transverse distribution of electron space charge in the column is the same as in proton beam. Electrostatic electrodes are to control the accumulation and release of the electrons. Ions are not magnetized and drift away without affecting the compensation.

  8. 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.

  9. 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.

  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. 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.

  12. High energy electron beam irradiation of water, wastewater and sludge

    SciTech Connect

    Kurucz, C.N.; Waite, T.D.; Cooper, W.J.; Nickelsen, M.J.

    1991-12-31

    Research on the use of high energy electrons for treating water, wastewater and wastewater sludge has been under way for approximately twenty years. Much of this work has been supported by the National Science Foundation and an overview of that support has been reported on by Bryan. The results of recent work, especially the most recent project at the Miami Electron Beam Research Facility (EBRF), has stimulated great interest in the area of utilizing this technology for treating environmental problems. This facility is located at the Miami Dade Central District (Virginia Key) Wastewater Treatment Plant in Miami, Florida, and is unique in that it is the only electron beam system set up for large scale treatment of wastewater. High energy electron beam irradiation as a treatment process has potential application in many areas of water, wastewater and industrial waste treatment and in the area of toxic/hazardous waste disposal. This chapter will discuss these applications and present selected results to date. Electron beam technology is described and the underlying chemistry is reviewed to provide a basis for interpretation of results obtained so far, and to point out the necessary information on water quality that is required to quantitatively describe the effectiveness of the process. 55 refs., 10 figs., 5 tabs.

  13. Electron-beam-assisted dry etching for GaAs using electron cyclotron resonance plasma electron source

    NASA Astrophysics Data System (ADS)

    Watanabe, Heiji; Matsui, Shinji

    1992-12-01

    Electron-beam (EB)-assisted dry etching of GaAs using Ar electron cyclotron resonance (ECR) plasma as an electron shower source is developed to achieve a low energy and high current density electron beam (EB). The rate of EB-assisted dry etching is more than ten times larger than for Cl2 gas etching.It is confirmed, through photoluminescence measurement, that this etching method causes less damage than ion beam techniques and is very effective for damaged layer removal. Using this technique, a 0.4 μm linewidth low-damage fine structure of GaAs was fabricated.

  14. 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.

  15. 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.

  16. Electron Beam Instrumentation Techniques Using Coherent Radiation

    NASA Astrophysics Data System (ADS)

    Wang, D. X.

    1997-05-01

    In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, advanced accelerators such as laser or plasma wakefield accelerators, and Compton backscattering X-ray sources. A short bunch length is needed to meet various requirements such as high peak current, low momentum spread, high luminosity, small ratio of bunch length to plasma wavelength, or accurate timing. Meanwhile, much progress has been made on photoinjectors and different magnetic and RF bunching schemes to produce very short bunches. Measurement of those short bunches becomes essential to develop, characterize, and operate such demanding machines. Conventionally, bunch duration of short electron bunches is measured by transverse RF deflecting cavities or streak camera. With such devices it becomes very challenging to measure bunch length down to a few hundred femtoseconds. Many frequency domain techniques have been recently developed, based on a relation between bunch profile and coherent radiation spectrum. These techniques provide excellent performance for short bunches. In this paper, coherent radiation and its applications to bunch length measurement will be discussed. A strategy for bunch length control at Jefferson Lab will be presented, which includes a noninvasive coherent synchrotron radiation (CSR) monitor, a zero-phasing technique used to calibrate the CSR detector, and phase transfer measurement used to correct RF phase drifts.

  17. 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.

  18. Developments in low energy electron beam machinery and processes

    NASA Astrophysics Data System (ADS)

    Nablo, S. V.; Chrusciel, J.; Cleghorn, D. A.; Rangwalla, I.

    2003-08-01

    The engineering and development of a new generation of low energy, high power electron beam equipment is presented. Operating voltages range from 80 to 125 kV at widths to 1.65 m. At 110 kV these systems deliver 1000 Mrad m min -1 at 110 kV. Equipment operating power levels and their impact on reducing equipment size and cost are reviewed. The advantages of electron curing at these reduced operating voltages are described. The principles of the electron beam fluidized bed process for the treatment of powders and particulates in high-speed pneumatic transport are discussed. Typical system performances for polymer dissociation and crosslinking, or for agroproduct disinfestation and disinfection are presented. A process for the sterilization of polymer food containers employing the injection of low energy electrons through the open mouth has been developed. Some of its sterilization capabilities for bottles up to 2 l capacity are described.

  19. 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.

  20. 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.

  1. Slit disk for modified faraday cup diagnostic for determining power density of electron and ion beams

    DOEpatents

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

    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.

  2. 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.}

  3. Recent developments in stored polarized electron positron beams

    NASA Astrophysics Data System (ADS)

    Rossmanith, R.

    1992-01-01

    In nearly all electron or positron storage rings the beams are polarized vertically by the Sokolov-Ternov effect. The existence of polarized beams was established both in low energy rings such as ACO (the first storage ring in which the Sokolov-Ternov polarization effect was measured), BESSY, and VEPP2 and in high energy rings such as TRISTAN, HERA, and LEP. As a result beam polarization seems to be an inherent property of electron-positron rings. It should be noted that this free polarization was never used for high energy experiments except in those instances in which exact energy calibration measurements were performed. Proposals for using stored polarized beams for internal target experiments are fairly new. Experiments with polarized longitudinal beams in LEP are still in the stage of planning. The efforts of the last few years are summarized in order to arrive at a better understanding of the spin dynamics in electron positron storage rings and to compare the experimental results with the theory. Polarimeters are not discussed.

  4. Feasibility of ceramic joining with high energy electron beams

    SciTech Connect

    Turman, B.N.; Glass, S.J.; Halbleib, J.A.; Helmich, D.R.; Loehman, R.E.; Clifford, J.R.

    1995-01-01

    Joining structural ceramics is possible using high melting point metals such as Mo and Pt that are heated with a high energy electron beam, with the potential for producing joints with high temperature capability. A 10 MeV electron beam can penetrate through 1 cm of ceramic, offering the possibility of buried interface joining. Because of transient heating and the lower heat capacity of the metal relative to the ceramic, a pulsed high power beam has the potential for melting the metal without decomposing or melting the adjacent ceramic. The authors have demonstrated the feasibility of the process with a series of 10 MeV, 1 kW electron beam experiments. Shear strengths up to 28 NTa have been measured for Si{sub 3}N{sub 4}-Mo-Si{sub 3}N{sub 4}. These modest strengths are due to beam non-uniformity and the limited area of bonding. The bonding mechanism appears to be a thin silicide reaction layer. Si{sub 3}N{sub 4}-Si{sub 3}N{sub 4} joints with no metal layer were also produced, apparently bonded an yttrium apatite grain boundary phase.

  5. 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.

  6. Physics Reach of Electron-Capture Neutrino Beams

    NASA Astrophysics Data System (ADS)

    Bernabeu, J.; Burguet-Castell, J.; Espinoza, C.; Lindroos, M.

    2006-05-01

    To complete the picture of neutrino oscillations two fundamental parameters need to be measured, θ and δ. The next generation of long baseline neutrino oscillation experiments -superbeams, betabeams and neutrino factories- indeed take aim at measuring them. Here we explore the physics reach of a new candidate: an electron-capture beam. Emphasis is made on its feasibility thanks to the recent discovery of nuclei that decay fast through electron capture, and on the interplay with a betabeam (its closest relative).

  7. Electron Beam Welding of a Depleted Uranium Alloy to Niobium Using a Calibrated Electron Beam Power Density Distribution

    SciTech Connect

    Elmer, J.W.; Teruya, A.T.; Terrill, P.E.

    2000-08-21

    Electron beam test welds were made joining flat plates of commercially pure niobium to a uranium-6wt%Nb (binary) alloy. The welding parameters and joint design were specifically developed to minimize mixing of the niobium with the U-6%Nb alloy. A Modified Faraday Cup (MFC) technique using computer-assisted tomography was employed to determine the precise power distribution of the electron beam so that the welding parameters could be directly transferred to other welding machines and/or to other facilities.

  8. Studies of the mechanism of electron beam induced deposition (EBID)

    NASA Astrophysics Data System (ADS)

    Choi, Young Ryong

    The controlled deposition of metals resulting from the passage of an ion beam through an atmosphere of a suitable precursor gas is a well-established procedure for micro scale materials manipulation. While the ion beam technique is rapid and reliable it has the disadvantage that the beam itself can ablate and contaminate the target with Gallium or other materials, and the fact that ion optics are less widely accessible than electron optical columns. We have therefore been investigating the theory and practice of depositing metal using an electron beam and variety of precursor gases. The aim of this work is to develop techniques that can be applied to the repair of the optical, ultra-violet (UV) and extreme ultra-violet (EUV) masks used in high performance photo-lithography. This thesis is concentrated on electron beam induced deposition (EBID) performed in a commercial Scanning Electron Microscope (SEM). For EBID experiments, we have developed a gas injection system for the specimen chamber of a standard SEM which is able to control the pressure and the delivery flow rate of gas for experiment. Studies of factors that control the properties of the deposition---such as the electron-gas interactions, the effects of gas pressure, and the temperature of the substrate---have been made and experiments to determine the fundamental mechanisms of EBID---such as which types of electrons are responsible for the initial interaction event with the precursor---have been carried out and analyzed and systematically studied to determine the optimum conditions for the practical application of the EBID approach. Finally the practical applications of the EBID have been applied to repair of masks.

  9. 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

  10. Beam Conditioning for Free Electron Lasers:Consequences and Methods

    SciTech Connect

    Wolski, A.; Penn, G.; Sessler, A.; Wurtele, J.; /LBL, Berkeley /UC, Berkeley, Astron. Dept.

    2010-12-14

    The consequences of beam conditioning in four example cases [VISA, a soft x-ray free-electron laser (FEL), LCLS, and a 'Greenfield' FEL] are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance and, furthermore, allows for stronger focusing in the undulator. Simulations show higher saturation power, with gain lengths reduced by a factor of 2 or more. The beam dynamics in a general conditioning system are studied, with 'matching conditions' derived for achieving conditioning without growth in the effective emittance. Various conditioning lattices are considered, and expressions derived for the amount of conditioning provided in each case when the matching conditions are satisfied. These results show that there is no fundamental obstacle to producing beam conditioning, and that the problem can be reduced to one of proper lattice design. Nevertheless, beam conditioning will not be easy to implement in practice.

  11. Beam conditioning for free electron lasers: Consequences and methods

    NASA Astrophysics Data System (ADS)

    Wolski, A.; Penn, G.; Sessler, A.; Wurtele, J.

    2004-08-01

    The consequences of beam conditioning in four example cases [VISA, a soft x-ray free-electron laser (FEL), LCLS, and a “Greenfield” FEL] are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance and, furthermore, allows for stronger focusing in the undulator. Simulations show higher saturation power, with gain lengths reduced by a factor of2 or more. The beam dynamics in a general conditioning system are studied, with “matching conditions” derived for achieving conditioning without growth in the effective emittance. Various conditioning lattices are considered, and expressions derived for the amount of conditioning provided in each case when the matching conditions are satisfied. These results show that there is no fundamental obstacle to producing beam conditioning, and that the problem can be reduced to one of proper lattice design. Nevertheless, beam conditioning will not be easy to implement in practice.

  12. Research aims at development of laser-guided electron beam

    NASA Astrophysics Data System (ADS)

    Kozicharow, E.

    1985-02-01

    The U.S. Department of Defense is conducting a technology development program that may result in the stationing of a laser-guided electron beam weapon, at ionospheric altitudes of 80-600 km, for the interception and destruction of Soviet ICBMs at ranges of more than 1000 miles. This research program is pursuing the principle of ion-focused propagation, which resolves the problem of atmospheric beam scattering by ionizing a channel in the atmospheric medium with a laser. Also discussed is the development status of space-based particle beams and lasers, ground-based laser systems employing orbiting mirror platforms for beam aiming, and nuclear device-powered directed energy weapons.

  13. Characterization of 2219 Aluminum Produced by Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M. B.; Hafley, Robert A.

    2002-01-01

    Researchers at NASA Langley Research Center are developing a new electron beam freeform fabrication (EB F(sup 3)) technique to fabricate metal parts. This process introduces metal wire into a molten pool created by a focused electron beam. Potential aerospace applications for this technology include ground-based fabrication of airframe structures and on-orbit construction and repair of space components and structures. Processing windows for reliably producing high quality 2219 aluminum parts using the EB F(sup 3) technique are being defined. The effects of translation speed, wire feed rate, and beam power on the resulting microstructures and mechanical properties are explored. Tensile properties (ultimate tensile strength, yield strength, and elongation) show little effect over the range of processing conditions tested. Basic processing-microstructure-property correlations are drawn for the EB F(sup 3) process.

  14. 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.

  15. Melt pool dynamics during selective electron beam melting

    NASA Astrophysics Data System (ADS)

    Scharowsky, T.; Osmanlic, F.; Singer, R. F.; Körner, C.

    2014-03-01

    Electron beam melting is a promising additive manufacturing technique for metal parts. Nevertheless, the process is still poorly understood making further investigations indispensable to allow a prediction of the part's quality. To improve the understanding of the process especially the beam powder interaction, process observation at the relevant time scale is necessary. Due to the difficult accessibility of the building area, the high temperatures, radiation and the very high scanning speeds during the melting process the observation requires an augmented effort in the observation equipment. A high speed camera in combination with an illumination laser, band pass filter and mirror system is suitable for the observation of the electron beam melting process. The equipment allows to observe the melting process with a high spatial and temporal resolution. In this paper the adjustment of the equipment and results of the lifetime and the oscillation frequencies of the melt pool for a simple geometry are presented.

  16. LINEAR ELECTROSTATIC INSTABILITY OF THE ELECTRON BEAM ION SOURCE

    SciTech Connect

    Litwin, C.; Vella, M.C.; Sessler, A.

    1981-12-01

    Linear plasma fluid theory is used to study the stability of a cold electron beam in Brillouin equilibrium which passes through a stationary cold ion background, with particular interest in stability for parameters relevant to EBIS devices. Dispersion is studied both analytically and numerically. For {ell}=0, the usual infinite medium two stream instability condition is shown to correspond to a requirement that beam perveance exceed a minimum value, P>33 {micro}pervs; hence, this mode is stable for EBIS (P {approx} l{micro}perv). The Brillouin equilibrium rotation is shown to cause an electron-ion rotating stream instability, which is convectively unstable. The {ell}=1 mode is also found to be unstable. Higher modes numbers, {ell}>1, are unstable, but have reduced growth. Instability is only weakly affected by finite beam radius and boundary conditions.

  17. 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. PMID:26319180

  18. 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.

  19. Advanced Diagnostics for Developing High-Brightness Electron Beams

    SciTech Connect

    Ben-Zvi, I.; Babzien, M.; Malone, R.; Wang, X.-J.; Yakimenko, V.

    1998-11-24

    The production of high-brightness particle beams calls for the development of advanced beam diagnostics. High brightness beams, meaning beams with a high density in phase space, are important for many applications, such as short-wavelength Free-Electron Lasers and advanced accelerator systems. A diagnostic that provides detailed information on the density distribution of the electron bunch in multi-dimensional phase-space is an essential tool for obtaining small emittance at a high charge. This diagnostic system has been developed at Brookhaven National Laboratory. One component of the system is the measurement of a slice emittance which provides a measurement of transverse beam properties (such as emittance) as a function of the longitudinal position. Changing the laser pulse profile of a photocathode RF gun has been suggested as one way to achieve non-linear emittance compensation and improve the brightness and that can be diagnosed by the slice emittance system. The other element of the diagnostic is the tomographic reconstruction of the transverse phase. In our work we give special attention to the accuracy of the phase space reconstruction and present an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases. This high precision phase space tomography together with the ability to modify the radial charge distribution of the electron beam presents an opportunity to improve the emittance and apply non-linear radial emittance corrections. Combining the slice emittance and tomography diagnostics leads to an unprecedented visualization of phase space distributions in 5 dimensional phase-space and an opportunity to perform high-order emittance corrections. This should lead to great improvements in the beam brightness.

  20. ADVANCED DIAGNOSTICS FOR DEVELOPING HIGH-BRIGHTNESS ELECTRON BEAMS.

    SciTech Connect

    BEN-ZVI,I.

    1998-11-24

    The production of high-brightness particle beams calls for the development of advanced beam diagnostics. High brightness beams, meaning beams with a high density in phase space, are important for many applications, such as short-wavelength Free-Electron Lasers and advanced accelerator systems. A diagnostic that provides detailed information on the density distribution of the electron bunch in multi-dimensional phase-space is an essential tool for obtaining small emittance at a high charge. This diagnostic system has been developed at Brookhaven National Laboratory. One component of the system is the measurement of a slice emittance which provides a measurement of transverse beam properties (such as emittance) as a function of the longitudinal position. Changing the laser pulse profile of a photocathode RF gun has been suggested as one way to achieve non-linear emittance compensation and improve the brightness and that can be diagnosed by the slice emittance system. The other element of the diagnostic is the tomographic reconstruction of the transverse phase. In our work we give special attention to the accuracy of the phase space reconstruction and present an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases. This high precision phase space tomography together with the ability to modify the radial charge distribution of the electron beam presents an opportunity to improve the emittance and apply non-linear radial emittance corrections. Combining the slice emittance and tomography diagnostics leads to an unprecedented visualization of phase space distributions in 5 dimensional phase-space and an opportunity to perform high-order emittance corrections. This should lead to great improvements in the beam brightness.

  1. 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%.

  2. The physics of FEL in an infinite electron beam

    SciTech Connect

    Wang, G.; Litvinenko, V.N.; Webb, S.

    2010-10-07

    We solve linearized Vlasov-Maxwell FEL equations for a 3-D perturbation in the infinite electron beam with Lorentzian energy distributions using paraxial approximation. We present analytical solutions for various initial perturbations and discuss the effect of optical guiding in such system.

  3. 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.

  4. Turbulent electron beams generated by magnetron injection guns

    NASA Astrophysics Data System (ADS)

    Kalinin, Yu. A.; Starodubov, A. V.; Mushtakov, A. V.

    2011-06-01

    A detailed experimental investigation of oscillators based on a magnetron injection gun is carried out. Experimental data show that such oscillators offer a considerable advantage over other similar devices; namely, they are capable of generating powerful wideband noiselike microwave oscillations. This is because magnetron injection guns generate turbulent electron beams at their exit.

  5. Electron beam switched discharge for rapidly pulsed lasers

    DOEpatents

    Pleasance, Lyn D.; Murray, John R.; Goldhar, Julius; Bradley, Laird P.

    1981-01-01

    Method and apparatus for electrical excitation of a laser gas by application of a pulsed voltage across the gas, followed by passage of a pulsed, high energy electron beam through the gas to initiate a discharge suitable for laser excitation. This method improves upon current power conditioning techniques and is especially useful for driving rare gas halide lasers at high repetition rates.

  6. Compact pulsed electron beam system for microwave generation

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.; Deb, P.; Shukla, R.; Banerjee, P.; Prabaharan, T.; Adhikary, B.; Verma, R.; Sharma, A.; Shyam, A.

    2012-11-01

    A compact 180 kV electron beam system is designed for high power microwave generation. The electron beam system is consists of a secondary energy storage device, which can deliver energy to the load at faster rate than usual primary energy storage system such as tesla transformers or marx generator. The short duration, high voltage pulse with fast rise time and good flattop is applied to vacuum diode for high power microwave generation. The compact electron beam system is made up of single turn primary tesla transformer which charges a helical pulse forming line and transfers its energy to vacuum diode through a high voltage pressurized spark gap switch. We have used helical pulse forming line which has higher inductance as compared to coaxial pulse forming line, which in turns increases, the pulse width and reduce the length of the pulse forming line. Water dielectric medium is used because of its high dielectric constant, high dielectric strength and efficient energy storage capability. The time dependent breakdown property and high relative permittivity of water makes it an ideal choice for this system. The high voltage flat-top pulse of 90 kV, 260 ns is measured across the matched load. In this article we have reported the design details, simulation and initial experimental results of 180 kV pulsed electron beam system for high power microwave generation.

  7. Short electron beam bunch characterization through measurement of terahertz radiation

    SciTech Connect

    Shukui Zhang; Stephen Benson; David Douglas; Michelle D. Shinn; Gwyn Williams

    2004-08-01

    This paper presents the measurement of sub-picosecond relativistic electron beam bunch length by analyzing the spectra of the coherent terahertz pulses through Kramers-Kronig transformation. The results are compared with autocorrelation from a scanning polarization autocorrelator that measures the coherent optical transition radiation. The limitations of the different methods to such a characterization are discussed.

  8. Electron Beam Cured Epoxy Resin Composites for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.; Meador, Michael A.

    1997-01-01

    Electron beam curing of Polymer Matrix Composites (PMC's) is a nonthermal, nonautoclave curing process that has been demonstrated to be a cost effective and advantageous alternative to conventional thermal curing. Advantages of electron beam curing include: reduced manufacturing costs; significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvement in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance the electron beam curing of PMC technology. Over the last several years a significant amount of effort within the CRADA has been devoted to the development and optimization of resin systems and PMCs that match the performance of thermal cured composites. This highly successful materials development effort has resulted in a board family of high performance, electron beam curable cationic epoxy resin systems possessing a wide range of excellent processing and property profiles. Hundreds of resin systems, both toughened and untoughened, offering unlimited formulation and processing flexibility have been developed and evaluated in the CRADA program.

  9. Optical guiding and beam bending in free-electron lasers

    SciTech Connect

    Scharlemann, E.T.

    1987-01-01

    The electron beam in a free-electron laser (FEL) can act as an optical fiber, guiding or bending the optical beam. The refractive and gain effects of the bunched electron beam can compensate for diffraction, making possible wigglers that are many Rayleigh ranges (i.e., characteristic diffraction lengths) long. The origin of optical guiding can be understood by examining gain and refractive guiding in a fiber with a complex index of refraction, providing a mathematical description applicable also to the FEL, with some extensions. In the exponential gain regime of the FEL, the electron equations of motion must be included, but a self-consistent description of exponential gain with diffraction fully included becomes possible. The origin of the effective index of refraction of an FEL is illustrated with a simple example of bunched, radiating dipoles. Some of the properties of the index of refraction are described. The limited experimental evidence for optical beam bending is summarized. The evidence does not yet provide conclusive proof of the existence of optical guiding, but supports the idea. Finally, the importance of refractive guiding for the performance of a high-gain tapered-wiggler FEL amplifier is illustrated with numerical simulations.

  10. Split glass tube assures quality in electron beam brazing

    NASA Technical Reports Server (NTRS)

    Kressin, W. J.

    1966-01-01

    Sealed enclosure of heat-resistant glass tubing and silicone rubber molds provide good visibility for electron beam brazing of metal tubes in an inert gas atmosphere. The glass tubing and rubber molds, which are bonded together, are easily applied to and removed from the brazing area by operation of a clamp.

  11. Titania-assisted electron-beam and synchrotron lithography

    NASA Astrophysics Data System (ADS)

    Skorb, Ekaterina V.; Grützmacher, Detlev; Dais, Christian; Guzenko, Vitaliy A.; Sokolov, Valeriy G.; Gaevskaya, Tatjana V.; Sviridov, Dmitry V.

    2010-08-01

    Novel imaging layer technology for electron-beam and extreme-ultraviolet lithographic processes based upon generation of Pd nanoparticles in the Pd2 + -loaded TiO2 films was developed. The electroless metallization of the patterned TiO2:Pd2 + films yields both negative and positive nickel images with resolution down to ~ 100 nm.

  12. Titania-assisted electron-beam and synchrotron lithography.

    PubMed

    Skorb, Ekaterina V; Grützmacher, Detlev; Dais, Christian; Guzenko, Vitaliy A; Sokolov, Valeriy G; Gaevskaya, Tatjana V; Sviridov, Dmitry V

    2010-08-01

    Novel imaging layer technology for electron-beam and extreme-ultraviolet lithographic processes based upon generation of Pd nanoparticles in the Pd(2+)-loaded TiO(2) films was developed. The electroless metallization of the patterned TiO(2):Pd(2+) films yields both negative and positive nickel images with resolution down to approximately 100 nm. PMID:20634573

  13. Generation of Electron Bessel Beams with Nondiffractive Spreading by a Nanofabricated Annular Slit

    NASA Astrophysics Data System (ADS)

    Saitoh, Koh; Hirakawa, Kazuma; Nambu, Hiroki; Tanaka, Nobuo; Uchida, Masaya

    2016-04-01

    The shaping of a wavefront of free electrons has been experimentally realized very recently. We report the generation of an electron Bessel beam using a nanofabricated annular slit. We directly observe that electron Bessel beams propagate while maintaining a narrow beam width over a long propagation distance. In addition, we experimentally verify the self-healing property of these electron beams, which can reconstruct their shape after passing an obstacle. The experimental results are compared with simulation results of the propagation including a hexagonal slit. The present technique of electron Bessel beam generation can be used to develop a novel electron-beam-shaping, an atomic manipulation technique, and a new electron microscopy.

  14. Generating a uniform transverse distributed electron beam along a beam line

    NASA Astrophysics Data System (ADS)

    Jiao, Yi; Cui, Xiao-Hao

    2015-11-01

    It has been reported that transverse distribution shaping can help to further enhance the energy extraction efficiency in a terawatt, tapered X-ray free-electron laser. Thus, methods of creating and keeping an almost uniform transverse distributed (UTD) beam within undulators are required. This study shows that a UTD electron beam can be generated within evenly distributed drift sections where undulators can be placed, by means of octupoles and particular optics. A specific design is presented, and numerical simulations are performed to verify the proposed method. Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (2015009)

  15. 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.

  16. Numerical model of the plasma formation at electron beam welding

    SciTech Connect

    Trushnikov, D. N.; Mladenov, G. M.

    2015-01-07

    The model of plasma formation in the keyhole in liquid metal as well as above the electron beam welding zone is described. The model is based on solution of two equations for the density of electrons and the mean electron energy. The mass transfer of heavy plasma particles (neutral atoms, excited atoms, and ions) is taken into account in the analysis by the diffusion equation for a multicomponent mixture. The electrostatic field is calculated using the Poisson equation. Thermionic electron emission is calculated for the keyhole wall. The ionization intensity of the vapors due to beam electrons and high-energy secondary and backscattered electrons is calibrated using the plasma parameters when there is no polarized collector electrode above the welding zone. The calculated data are in good agreement with experimental data. Results for the plasma parameters for excitation of a non-independent discharge are given. It is shown that there is a need to take into account the effect of a strong electric field near the keyhole walls on electron emission (the Schottky effect) in the calculation of the current for a non-independent discharge (hot cathode gas discharge). The calculated electron drift velocities are much bigger than the velocity at which current instabilities arise. This confirms the hypothesis for ion-acoustic instabilities, observed experimentally in previous research.

  17. Reversible Electron Beam Heating for Suppression of Microbunching Instabilities at Free-Electron Lasers

    SciTech Connect

    Behrens, Christopher; Huang, Zhirong; Xiang, Dao; /SLAC

    2012-05-30

    The presence of microbunching instabilities due to the compression of high-brightness electron beams at existing and future x-ray free-electron lasers (FELs) results in restrictions on the attainable lasing performance and renders beam imaging with optical transition radiation impossible. The instability can be suppressed by introducing additional energy spread, i.e., heating the electron beam, as demonstrated by the successful operation of the laser heater system at the Linac Coherent Light Source. The increased energy spread is typically tolerable for self-amplified spontaneous emission FELs but limits the effectiveness of advanced FEL schemes such as seeding. In this paper, we present a reversible electron beam heating system based on two transverse deflecting radio-frequency structures (TDSs) upstream and downstream of a magnetic bunch compressor chicane. The additional energy spread is introduced in the first TDS, which suppresses the microbunching instability, and then is eliminated in the second TDS. We show the feasibility of the microbunching gain suppression based on calculations and simulations including the effects of coherent synchrotron radiation. Acceptable electron beam and radio-frequency jitter are identified, and inherent options for diagnostics and on-line monitoring of the electron beam's longitudinal phase space are discussed.

  18. A Gridded Electron Gun for a Sheet Beam Klystron

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    Calabazas Creek Research, Inc.(CCR) is developing rectangular, gridded, thermionic, dispenser-cathode guns for sheet beam devices. The first application is expected to be klystrons for advanced particle accelerators and colliders. The current generation of accelerators typically use klystrons with a cylindrical beam generated by a Pierce-type electron gun. As RF power is pushed to higher levels, space charge forces in the electron beam limit the amount of current that can be transmitted at a given voltage. The options are to increase the beam voltage, leading to problems with X-Ray shielding and modulator and power supply design, or to develop new techniques for lowering the space charge forces in the electron beam. In this device, the beam has a rectangular cross section. The thickness is constrained as it would in a normal, cylindrically symmetric klystron with a Pierce gun. However, the width of the beam is many times the thickness, and the resulting cross sectional area is much larger than in the conventional device. This allows much higher current and/or a lower voltage before space charge forces become too high. The current program addresses issues related to beam formation at the emitter surface, design and implementation of shadow and control grids in a rectangular geometry. It is directed toward a robust, cost-effective, and reliable mechanical design. A prototype device will be developed that will operate at 415 kV, 250 A for an 80 MW, X-Band, sheet-beam klystron. The cathode will have 100 cm2 of cathode area with an average cathode current loading of 2.5 A/cm2. For short pulse formation, the use of a grid was chosen. The gun has been designed with a combination of 2-D and 3-D codes. 2-D codes were used to determine the starting point for the electrodes to produce the compression (which is in only 1 direction.) These results showed that a very high quality beam could be achieved even in the presence of the shadow grid. 3-D results have shown that the

  19. Device and method for electron beam heating of a high density plasma

    DOEpatents

    Thode, L.E.

    A device and method for relativistic electron beam heating of a high density plasma in a small localized region are described. A relativistic electron beam generator produces a high voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high density target plasma which typically comprises DT, DD, hydrogen boron or similar thermonuclear gas at a density of 10/sup 17/ to 10/sup 20/.

  20. Undulator radiation driven by laser-wakefield accelerator electron beams

    NASA Astrophysics Data System (ADS)

    Wiggins, S. M.; Anania, M. P.; Welsh, G. H.; Brunetti, E.; Cipiccia, S.; Grant, P. A.; Reboredo, D.; Manahan, G.; Grant, D. W.; Jaroszynski, D. A.

    2015-05-01

    The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laserplasma accelerators for the production of ultra-short electron bunches with subsequent generation of coherent, bright, short-wavelength radiation pulses. The new Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) will develop a wide range of applications utilising such light sources. Electron bunches can be propagated through a magnetic undulator with the aim of generating fully coherent free-electron laser (FEL) radiation in the ultra-violet and Xrays spectral ranges. Demonstration experiments producing spontaneous undulator radiation have been conducted at visible and extreme ultra-violet wavelengths but it is an on-going challenge to generate and maintain electron bunches of sufficient quality in order to stimulate FEL behaviour. In the ALPHA-X beam line experiments, a Ti:sapphire femtosecond laser system with peak power 20 TW has been used to generate electron bunches of energy 80-150 MeV in a 2 mm gas jet laser-plasma wakefield accelerator and these bunches have been transported through a 100 period planar undulator. High peak brilliance, narrow band spontaneous radiation pulses in the vacuum ultra-violet wavelength range have been generated. Analysis is provided with respect to the magnetic quadrupole beam transport system and subsequent effect on beam emittance and duration. Requirements for coherent spontaneous emission and FEL operation are presented.