Science.gov

Sample records for electron beam energy

  1. Low energy electron magnetometer using a monoenergetic electron beam

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    SciTech Connect

    Seletskiy, Sergei M.

    2005-01-01

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

  3. Electron energy distribution produced by beam-plasma discharge

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  4. Electron energy distribution produced by beam-plasma discharge

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  5. 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.

  6. 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.

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

    SciTech Connect

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

    2014-02-15

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

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

    PubMed

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

    2014-02-01

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

  9. 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.

  10. Energy measurement of electron beams by Compton scattering

    NASA Technical Reports Server (NTRS)

    Keppel, Cynthia

    1995-01-01

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

  11. Energy measurement of electron beams by Compton scattering

    NASA Technical Reports Server (NTRS)

    Keppel, Cynthia

    1995-01-01

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

  12. Plasma Focusing of High Energy Density Electron and Positron Beams

    SciTech Connect

    Ng, Johnny S.T.

    2000-10-09

    We present results from the SLAC E-150 experiment on plasma focusing of high energy density electron and, for the first time, positron beams. We also present results on plasma lens-induced synchrotron radiation, longitudinal dynamics of plasma focusing, and laser- and beam-plasma interactions.

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

    PubMed

    Ratner, D

    2013-08-23

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

  14. 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

  15. SHEEBA: A spatial high energy electron beam analyzer

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  16. A compact low-energy electron beam irradiator.

    PubMed

    Cho, Sun Oh; Kim, Min; Lee, Byung Cheol; Jeong, Young Uk; Cha, In-su; Choi, Jeong-sik

    2002-05-01

    A new compact low-energy electron beam irradiator has been developed. The irradiator generates an electron beam to the air with energy variable from 35 to 80 keV and with a maximum current of 1 mA. The irradiation area is 30 x 30 mm2. A special irradiation port is developed for this low-energy irradiator. The electron beam is generated from a thermionic LaB6 cathode in vacuum. The beam is extracted to the air through a havar foil window. The thickness of the window is 4.8 microm, it is vacuum-tightly connected to the window to support by an indium wire. A controlled bow geometry of the window helps the thin window withstand the vacuum pressure. Cold air generated from a vortex tube cools down both the window and its support in order to prevent the window from melting down, due to beam energy dissipated in the foil. We found that about 60% of the beam current is extracted to the air at 80 keV.

  17. 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.

  18. 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

  19. 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.

  20. Effects of energy spectrum on dose distribution calculations for high energy electron beams.

    PubMed

    Toutaoui, Abdelkader; Khelassi-Toutaoui, Nadia; Brahimi, Zakia; Chami, Ahmed Chafik

    2009-01-01

    In an early work we have demonstrated the possibility of using Monte Carlo generated pencil beams for 3D electron beam dose calculations. However, in this model the electron beam was considered as monoenergetic and the effects of the energy spectrum were taken into account by correction factors, derived from measuring central-axis depth dose curves. In the present model, the electron beam is considered as polyenergetic and the pencil beam distribution of a clinical electron beam, of a given nominal energy, is represented as a linear combination of Monte Carlo monoenergetic pencil beams. The coefficients of the linear combination describe the energy spectrum of the clinical electron beam, and are chosen to provide the best-fit between the calculated and measured central axis depth dose, in water. The energy spectrum is determined by the constrained least square method. The angular distribution of the clinical electron beam is determined by in-air penumbra measurements. The predictions of this algorithm agree very well with the measurements in the region near the surface, and the discrepancies between the measured and calculated dose distributions, behind 3D heterogeneities, are reduced to less than 10%. We have demonstrated a new algorithm for 3D electron beam dose calculations, which takes into account the energy spectra. Results indicate that the use of this algorithm leads to a better modeling of dose distributions downstream, from complex heterogeneities.

  1. Effects of energy spectrum on dose distribution calculations for high energy electron beams

    PubMed Central

    Toutaoui, Abdelkader; Khelassi-Toutaoui, Nadia; Brahimi, Zakia; Chami, Ahmed Chafik

    2009-01-01

    In an early work we have demonstrated the possibility of using Monte Carlo generated pencil beams for 3D electron beam dose calculations. However, in this model the electron beam was considered as monoenergetic and the effects of the energy spectrum were taken into account by correction factors, derived from measuring central-axis depth dose curves. In the present model, the electron beam is considered as polyenergetic and the pencil beam distribution of a clinical electron beam, of a given nominal energy, is represented as a linear combination of Monte Carlo monoenergetic pencil beams. The coefficients of the linear combination describe the energy spectrum of the clinical electron beam, and are chosen to provide the best-fit between the calculated and measured central axis depth dose, in water. The energy spectrum is determined by the constrained least square method. The angular distribution of the clinical electron beam is determined by in-air penumbra measurements. The predictions of this algorithm agree very well with the measurements in the region near the surface, and the discrepancies between the measured and calculated dose distributions, behind 3D heterogeneities, are reduced to less than 10%. We have demonstrated a new algorithm for 3D electron beam dose calculations, which takes into account the energy spectra. Results indicate that the use of this algorithm leads to a better modeling of dose distributions downstream, from complex heterogeneities. PMID:20126560

  2. Secondary Electron Generation by Low Energy Ion Beams

    SciTech Connect

    Joy, David Charles; Lin, Yinghong; Meyer III, Harry M; Demers, Hendrix; Newbury, Dale

    2006-01-01

    Low energy ion beams are being increasingly viewed as an alternative to, or even as areplacement for, low voltage SEMs. The beam interaction volumes in both cases are comparable in their size and their proximity to the sample surface, and both can produce high quality secondary electron images. However, although a cursory comparison of ion generated SE (iSE) and electron generated SE (eSE) images of the same area of a sample shows micrographs that can look very similar this is misleading because the nature of the iSE and eSE images are quite distinct. More experimental data and additional analysis of the beam interactions is therefore required if images are to be properly nterpreted.The yield de of eSE, rises rapidly with incident beam energy E reaching a maximum value which is typically in the range 1.5-2 and occurs at an energy of a few hundred eV before then falling away as about 1/E.. In the case of ion beam irradiation the kinetic production of iSE commences at a particle velocity of about 107cm/sec 30eV for He, (3keV for Ar) producing a yield di of iSE which rises almost linearly with the accelerating voltage and reaches typical values of 1.5 - 2.5 for energies of the order of 20- 30kV. Thus while at low energies the eSE and iSE yields are comparable in magnitude, at higher energies the iSE yield is an order of magnitude or more larger. The iSE yield will eventually each a maximum value and then begin to fall when once the interaction volume lies mostly below the escape depth of the SE. Both eSE and iSE yields also display a marked - although apparently chaotic - dependence on the atomic number of the target (Z2) and, in the ion case, on the atomic number of the ion (Z1) itself. In the electron case the minima in the SE yield versus Z2 plot correspond to shell filling but there is presently insufficient evidence to confirm if the same is true for the ion SE case. Because the stopping powers of ion and electrons, and hence their range in a given material, are

  3. Exotic X-ray Sources from Intermediate Energy Electron Beams

    SciTech Connect

    Chouffani, K.; Wells, D.; Harmon, F.; Jones, J.L.; Lancaster, G.

    2003-08-26

    High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, 'novel' x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic 'structure' of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR)

  4. Stable topological insulators achieved using high energy electron beams

    PubMed Central

    Zhao, Lukas; Konczykowski, Marcin; Deng, Haiming; Korzhovska, Inna; Begliarbekov, Milan; Chen, Zhiyi; Papalazarou, Evangelos; Marsi, Marino; Perfetti, Luca; Hruban, Andrzej; Wołoś, Agnieszka; Krusin-Elbaum, Lia

    2016-01-01

    Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder. Ubiquitous charged bulk defects, however, pull the Fermi energy into the bulk bands, denying access to surface charge transport. Here we demonstrate that irradiation with swift (∼2.5 MeV energy) electron beams allows to compensate these defects, bring the Fermi level back into the bulk gap and reach the charge neutrality point (CNP). Controlling the beam fluence, we tune bulk conductivity from p- (hole-like) to n-type (electron-like), crossing the Dirac point and back, while preserving the Dirac energy dispersion. The CNP conductance has a two-dimensional character on the order of ten conductance quanta and reveals, both in Bi2Te3 and Bi2Se3, the presence of only two quantum channels corresponding to two topological surfaces. The intrinsic quantum transport of the topological states is accessible disregarding the bulk size. PMID:26961901

  5. Stable topological insulators achieved using high energy electron beams.

    PubMed

    Zhao, Lukas; Konczykowski, Marcin; Deng, Haiming; Korzhovska, Inna; Begliarbekov, Milan; Chen, Zhiyi; Papalazarou, Evangelos; Marsi, Marino; Perfetti, Luca; Hruban, Andrzej; Wołoś, Agnieszka; Krusin-Elbaum, Lia

    2016-03-10

    Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder. Ubiquitous charged bulk defects, however, pull the Fermi energy into the bulk bands, denying access to surface charge transport. Here we demonstrate that irradiation with swift (∼2.5 MeV energy) electron beams allows to compensate these defects, bring the Fermi level back into the bulk gap and reach the charge neutrality point (CNP). Controlling the beam fluence, we tune bulk conductivity from p- (hole-like) to n-type (electron-like), crossing the Dirac point and back, while preserving the Dirac energy dispersion. The CNP conductance has a two-dimensional character on the order of ten conductance quanta and reveals, both in Bi2Te3 and Bi2Se3, the presence of only two quantum channels corresponding to two topological surfaces. The intrinsic quantum transport of the topological states is accessible disregarding the bulk size.

  6. Inverse planning of energy-modulated electron beams in radiotherapy

    SciTech Connect

    Gentry, John R. . E-mail: gentryj@gmh.org; Steeves, Richard; Paliwal, Bhudatt A.

    2006-01-01

    The use of megavoltage electron beams often poses a clinical challenge in that the planning target volume (PTV) is anterior to other radiosensitive structures and has variable depth. To ensure that skin as well as the deepest extent of the PTV receives the prescribed dose entails prescribing to a point beyond the depth of peak dose for a single electron energy. This causes dose inhomogeneities and heightened potential for tissue fibrosis, scarring, and possible soft tissue necrosis. Use of bolus on the skin improves the entrant dose at the cost of decreasing the therapeutic depth that can be treated. Selection of a higher energy to improve dose homogeneity results in increased dose to structures beyond the PTV, as well as enlargement of the volume receiving heightened dose. Measured electron data from a linear accelerator was used as input to create an inverse planning tool employing energy and intensity modulation using bolus (e-IMRT{sup TM}). Using tools readily available in a radiotherapy department, the applications of energy and intensity modulation on the central axis makes it possible to remove hot spots of 115% or more over the depths clinically encountered. The e-IMRT{sup TM} algorithm enables the development of patient-specific dose distributions with user-defined positions of peak dose, range, and reduced dose to points beyond the prescription point.

  7. Innovative energy efficient low-voltage electron beam emitters

    NASA Astrophysics Data System (ADS)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-03-01

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates.

  8. High energy electron beam processing experiments with induction accelerators

    NASA Astrophysics Data System (ADS)

    Goodman, D. L.; Birx, D. L.; Dave, V. R.

    1995-05-01

    Induction accelerators are capable of producing very high electron beam power for processing at energies of 1-10 MeV. A high energy electron beam (HEEB) material processing system based on all-solid-state induction accelerator technology is in operation at Science Research Laboratory. The system delivers 50 ns 500 A current pulses at 1.5 MeV and is capable of operating at high power (500 kW) and high (˜ 5 kHz) repetition rate. HEEB processing with induction accelerators is useful for a wide variety of applications including the joining of high temperature materials, powder metallurgical fabrication, treatment of organic-contaminated wastewater and the curing of polymer matrix composites. High temperature HEEB experiments at SRL have demonstrated the brazing of carbon-carbon composites to metallic substrates and the melting and sintering of powders for graded-alloy fabrication. Other experiments have demonstrated efficient destruction of low-concentration organic contaminants in water and low temperature free-radical cross-linking of fiber-reinforced composites with acrylated resin matrices.

  9. Retarding field energy analyzer for high energy pulsed electron beam measurements

    NASA Astrophysics Data System (ADS)

    Hu, Jing; Rovey, Joshua L.; Zhao, Wansheng

    2017-01-01

    A retarding field energy analyzer (RFEA) designed specifically for high energy pulsed electron beam measurements is described in this work. By proper design of the entrance grid, attenuation grid, and beam collector, this RFEA is capable of determining the time-resolved energy distribution of high energy pulsed electron beams normally generated under "soft vacuum" environment. The performance of the RFEA is validated by multiple tests of the leakage current, attenuation coefficient, and response time. The test results show that the retarding potential in the RFEA can go up to the same voltage as the electron beam source, which is 20 kV for the maximum in this work. Additionally, an attenuation coefficient of 4.2 is obtained in the RFEA while the percent difference of the rise time of the electron beam pulse before and after attenuation is lower than 10%. When compared with a reference source, the percent difference of the RFEA response time is less than 10% for fall times greater than 35 ns. Finally, the test results of the 10 kV pseudospark-based pulsed electron beam currents collected under varying retarding potentials are presented in this paper.

  10. Microwave Chip-Based Beam Splitter for Low-Energy Guided Electrons.

    PubMed

    Hammer, Jakob; Thomas, Sebastian; Weber, Philipp; Hommelhoff, Peter

    2015-06-26

    We present a novel beam splitter for low-energy electrons using a micro-structured guiding potential created above the surface of a planar microwave chip. Beam splitting arises from smoothly transforming the transverse guiding potential for an electron beam from a single-well harmonic confinement into a double well, thereby generating two separated output beams with 5 mm lateral spacing. Efficient beam splitting is observed for electron kinetic energies up to 3 eV, in excellent agreement with particle tracking simulations. We discuss prospects of this novel beam splitter approach for electron-based quantum matter-wave optics experiments.

  11. Energy Extraction from the Electron Beam in a Free Electron Laser Resonator Gaussian Mode.

    DTIC Science & Technology

    1983-01-01

    Elias, Juan Gallardo and Peter Goldstein N00014-80-C-0308 S. PF OR -ING ORGANIZATION NAME AND ADDRESS I . PROGRAM ELEMt.T PROJECT, TASK * ,’ niwxrsity...Elias, Juan Gallardo , Peter Goldstein Quantum Institue, University of California Santa Barbara, California 93106 ABSTRACT We present preliminary...QUANTUM INSTITUTE FREE ELECTRON LASER PROJECT Energy Extraction fran the Electron Beam in a Free Electron Laser Resonator Gaussian Mode Luis Elias, Juan

  12. 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)

  13. 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.

  14. Electron contamination in clinical high energy photon beams.

    PubMed

    Sjögren, R; Karlsson, M

    1996-11-01

    The electron contamination in photon beams has been investigated by means of contaminating lepton depth doses and dose profiles in different geometries with two 20 MV beams. Different components of this contamination have been investigated separately by systematically adding contamination to a "clean" reference field. At 20 MV, the air generated electrons were found to be almost negligible compared to the electrons originating from the accelerator head when measurements were performed in standard fields at SSDs between 80 and 120 cm. The total electron part of the depth dose curve was then almost the same, i.e., independent of SSD, when the collimator opening was held fixed. However, when different accessories such as a shaping block and different attenuating plates were located in the beam path below the collimators, a large SSD dependence of the electron contamination was noticed. A comparison was also made between two machines, one equipped with a multileaf collimator, with similar beam qualities at 20 MV. These measurements indicate that the interior view of the treatment head seen by the detector (mainly the flattening filter, monitor chamber, or other electron generating material) influences the magnitude of the electron contamination. When the collimator opening is decreased the electron contamination will also decrease as parts of the electron source will be shielded by the collimator blocks.

  15. Kinetic energy offsets for multicharged ions from an electron beam ion source.

    PubMed

    Kulkarni, D D; Ahl, C D; Shore, A M; Miller, A J; Harriss, J E; Sosolik, C E; Marler, J P

    2017-08-01

    Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar(4+) and Ar(8+) ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

  16. Kinetic energy offsets for multicharged ions from an electron beam ion source

    NASA Astrophysics Data System (ADS)

    Kulkarni, D. D.; Ahl, C. D.; Shore, A. M.; Miller, A. J.; Harriss, J. E.; Sosolik, C. E.; Marler, J. P.

    2017-08-01

    Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar4+ and Ar8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

  17. Optimized treatment planning using intensity and energy modulated proton and very-high energy electron beams

    NASA Astrophysics Data System (ADS)

    Yeboah, Collins

    2002-09-01

    Intensity and energy modulated radiotherapy dose planning with protons and very-high energy (50--250 MeV) electron beams has been investigated. A general-purpose inverse treatment planning (ITP) system that can be applied to any combination of proton, electron and photon radiation modalities in therapy has been developed. The new ITP program uses a very fast proton dose calculation engine and employs one of the most efficient optimization algorithms currently available. First, the ITP program was employed to investigate intensity-modulated proton therapy (IMPT) dose optimization for prostate cancer. The second application was to evaluate the potential of intensity-modulated very-high energy electron therapy (VHEET) for dose conformation. For an active proton beam delivery system the required energy resolution to reasonably implement energy modulation was found to be a function of the incident beams' energy spread and became coarser with increasing energy spread. For passive proton beam delivery systems the selection of the required depth resolution for inverse planning may not be critical as long as the depth resolution chosen is at least equal to FWHM/2 of the primary beam Bragg peak. In the study of the number of beam ports selected for IMPT treatment of the prostate, it was found that a maximum of three to four beams is required. Using proton beams for inverse planning of the prostate instead of photon beams gave the same or better target coverage while reducing the sensitive structure dose and normal tissue integral dose by up to 30% and 28% of the prescribed target dose, respectively. In evaluating the potential of VHEET beams for dose conformation, it was found that electron energies greater than 100 MeV are preferable for VHEET treatment of the prostate and that implementation of energy modulation in addition to intensity modulation has only a modest effect on the final dose distribution. VHEET treatment employing approximately nine beams was sufficient to

  18. Proposal for an x-ray free electron laser oscillator with intermediate energy electron beam.

    PubMed

    Dai, Jinhua; Deng, Haixiao; Dai, Zhimin

    2012-01-20

    Harmonic lasing of low-gain free electron laser oscillators has been experimentally demonstrated in the terahertz and infrared regions. Recently, the low-gain oscillator has been reconsidered as a promising candidate for hard x-ray free electron lasers, through the use of high reflectivity, high-resolution x-ray crystals. In this Letter, it is proposed to utilize a crystal-based cavity resonant at a higher harmonic of the undulator radiation, together with phase shifting, to enable harmonic lasing of the x-ray free electron laser oscillator, and hence allow the generation of hard x-ray radiation at a reduced electron beam energy. Results show that fully coherent free electron laser radiation with megawatt peak power, in the spectral region of 10-25 keV, can be generated with a 3.5 GeV electron beam.

  19. Electron energy distributions measured during electron beam/plasma interactions. [in E region

    NASA Technical Reports Server (NTRS)

    Jost, R. J.; Anderson, H. R.; Mcgarity, J. O.

    1980-01-01

    In the large vacuum facility at the NASA-Johnson Space Center an electron beam was projected 20 m parallel to B from a gun with variable accelerating potential (1.0 to 2.5 kV) to an aluminum target. The ionospheric neutral pressure and field were approximated. Beam electron energy distributions were measured directly using an electrostatic deflection analyzer and indirectly with a detector that responded to the X-rays produced by electron impact on the target. At low currents the distribution is sharply peaked at the acceleration potential. At high currents a beam plasma discharge occurs and electrons are redistributed in energy so that the former energy peak broadens to 10-15 percent FWHM with a strongly enhanced low energy tail. At the 10% of maximum point the energy spectrum ranges from less than 1/2 to 1.2 times the gun energy. The effect is qualitatively the same at all pitch angles and locations sampled.

  20. Surface modification of structural materials by low-energy high-current pulsed electron beam treatment

    SciTech Connect

    Panin, A. V. E-mail: kms@ms.tsc.ru; Kazachenok, M. S. E-mail: kms@ms.tsc.ru; Sinyakova, E. A.; Borodovitsina, O. M.; Ivanov, Yu. F.; Leontieva-Smirnova, M. V.

    2014-11-14

    Microstructure formation in surface layers of pure titanium and ferritic-martensitic steel subjected to electron beam treatment is studied. It is shown that low energy high-current pulsed electron beam irradiation leads to the martensite structure within the surface layer of pure titanium. Contrary, the columnar ferrite grains grow during solidification of ferritic-martensitic steel. The effect of electron beam energy density on the surface morphology and microstructure of the irradiated metals is demonstrated.

  1. Emittance and Energy Measurements of Low-Energy Electron Beam Using Optical Transition Radiation Techniques

    NASA Astrophysics Data System (ADS)

    Sakamoto, Fumito; Iijima, Hokuto; Dobashi, Katsuhiro; Imai, Takayuki; Ueda, Toru; Watanabe, Takahiro; Uesaka, Mitsuru

    2005-03-01

    Emittance and energy of an electron beam in the range of 8 to 22 MeV were measured via optical transition radiation (OTR) techniques. The beam divergence effect on observations of the far-field OTR image at low energies was studied by means of numerical analysis. The numerical analysis indicates that if the beam divergence is under 1.5 mrad, a simultaneous single-shot measurement of emittance and energy is possible. The results of the single-shot experiment agree with independent measurements conducted using the quadrupole scan method and an electron spectrometer. The experiments were performed with an S-band linac at the Nuclear Engineering Research Laboratory, The University of Tokyo (UTNL).

  2. A Feasibility Study of 50 nm Resolution with Low Energy Electron Beam Proximity Projection Lithography

    NASA Astrophysics Data System (ADS)

    Yoshizawa, Masaki; Savas, T. A.

    2002-01-01

    Patterns of 50 nm lines and spaces were demonstrated by low energy electron beam proximity lithography using 47-nm-thick poly methyl methacrylate (PMMA) and stencil masks fabricated by achromatic interference lithography (AIL). The result indicates the validity of the resolution analysis previously reported and the resolution capabilities of low energy electron beam proximity projection lithography (LEEPL) as a 50 nm node technology.

  3. Electron beam guiding by grooved SiO{sub 2} parallel plates without energy loss

    SciTech Connect

    Xue, Yingli; Yu, Deyang Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong

    2015-12-21

    Using a pair of grooved SiO{sub 2} parallel plates, stably guided electron beams were obtained without energy loss at 800–2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

  4. Low-Energy Plasma Focus Device as an Electron Beam Source

    PubMed Central

    Seong Ling, Yap; Naresh Kumar, Nitturi; Lian Kuang, Lim; Chiow San, Wong

    2014-01-01

    A low-energy plasma focus device was used as an electron beam source. A technique was developed to simultaneously measure the electron beam intensity and energy. The system was operated in Argon filling at an optimum pressure of 1.7 mbar. A Faraday cup was used together with an array of filtered PIN diodes. The beam-target X-rays were registered through X-ray spectrometry. Copper and lead line radiations were registered upon usage as targets. The maximum electron beam charge and density were estimated to be 0.31 μC and 13.5 × 1016/m3, respectively. The average energy of the electron beam was 500 keV. The high flux of the electron beam can be potentially applicable in material sciences. PMID:25544952

  5. Low-energy plasma focus device as an electron beam source.

    PubMed

    Khan, Muhammad Zubair; Ling, Yap Seong; Yaqoob, Ibrar; Kumar, Nitturi Naresh; Kuang, Lim Lian; San, Wong Chiow

    2014-01-01

    A low-energy plasma focus device was used as an electron beam source. A technique was developed to simultaneously measure the electron beam intensity and energy. The system was operated in Argon filling at an optimum pressure of 1.7 mbar. A Faraday cup was used together with an array of filtered PIN diodes. The beam-target X-rays were registered through X-ray spectrometry. Copper and lead line radiations were registered upon usage as targets. The maximum electron beam charge and density were estimated to be 0.31 μC and 13.5 × 10(16)/m(3), respectively. The average energy of the electron beam was 500 keV. The high flux of the electron beam can be potentially applicable in material sciences.

  6. Low-energy run of Fermilab Electron Cooler's beam generation system

    SciTech Connect

    Prost, Lionel; Shemyakin, Alexander; Fedotov, Alexei; Kewisch, Jorg; /Brookhaven

    2010-08-01

    As a part of a feasibility study of using the Fermilab Electron Cooler for a low-energy Relativistic Heavy Ion Collider (RHIC) run at Brookhaven National Laboratory (BNL), the cooler operation at 1.6 MeV electron beam energy was tested in a short beam line configuration. The main result of the study is that the cooler beam generation system is suitable for BNL needs. In a striking difference with running 4.3 MeV beam, no unprovoked beam recirculation interruptions were observed.

  7. Comparative dosimetric characterization for different types of detectors in high-energy electron beams

    NASA Astrophysics Data System (ADS)

    Lee, Chang Yeol; Kim, Woo Chul; Kim, Hun Jeong; Huh, Hyun Do; Park, Seungwoo; Choi, Sang Hyoun; Kim, Kum Bae; Min, Chul Kee; Kim, Seong Hoon; Shin, Dong Oh

    2017-02-01

    The purpose of this study is to perform a comparison and on analysis of measured dose factor values by using various commercially available high-energy electron beam detectors to measure dose profiles and energy property data. By analyzing the high-energy electron beam data from each detector, we determined the optimal detector for measuring electron beams in clinical applications. The dose linearity, dose-rate dependence, percentage depth dose, and dose profile of each detector were measured to evaluate the dosimetry characteristics of high-energy electron beams. The dose profile and the energy characteristics of high-energy electron beams were found to be different when measured by different detectors. Through comparison with other detectors based on the analyzed data, the microdiamond detector was found to have outstanding dose linearity, a low dose-rate dependency, and a small effective volume. Thus, this detector has outstanding spatial resolution and is the optimal detector for measuring electron beams. Radiation therapy results can be improved and related medical accidents can be prevented by using the procedure developed in this research in clinical practice for all beam detectors when measuring the electron beam dose.

  8. Absolute energy calibration for relativistic electron beams with pointing instability from a laser-plasma accelerator

    SciTech Connect

    Cha, H. J.; Choi, I. W.; Kim, H. T.; Kim, I J.; Nam, K. H.; Jeong, T. M.; Lee, J.

    2012-06-15

    The pointing instability of energetic electron beams generated from a laser-driven accelerator can cause a serious error in measuring the electron spectrum with a magnetic spectrometer. In order to determine a correct electron spectrum, the pointing angle of an electron beam incident on the spectrometer should be exactly defined. Here, we present a method for absolutely calibrating the electron spectrum by monitoring the pointing angle using a scintillating screen installed in front of a permanent dipole magnet. The ambiguous electron energy due to the pointing instability is corrected by the numerical and analytical calculations based on the relativistic equation of electron motion. It is also possible to estimate the energy spread of the electron beam and determine the energy resolution of the spectrometer using the beam divergence angle that is simultaneously measured on the screen. The calibration method with direct measurement of the spatial profile of an incident electron beam has a simple experimental layout and presents the full range of spatial and spectral information of the electron beams with energies of multi-hundred MeV level, despite the limited energy resolution of the simple electron spectrometer.

  9. Absolute energy calibration for relativistic electron beams with pointing instability from a laser-plasma accelerator.

    PubMed

    Cha, H J; Choi, I W; Kim, H T; Kim, I J; Nam, K H; Jeong, T M; Lee, J

    2012-06-01

    The pointing instability of energetic electron beams generated from a laser-driven accelerator can cause a serious error in measuring the electron spectrum with a magnetic spectrometer. In order to determine a correct electron spectrum, the pointing angle of an electron beam incident on the spectrometer should be exactly defined. Here, we present a method for absolutely calibrating the electron spectrum by monitoring the pointing angle using a scintillating screen installed in front of a permanent dipole magnet. The ambiguous electron energy due to the pointing instability is corrected by the numerical and analytical calculations based on the relativistic equation of electron motion. It is also possible to estimate the energy spread of the electron beam and determine the energy resolution of the spectrometer using the beam divergence angle that is simultaneously measured on the screen. The calibration method with direct measurement of the spatial profile of an incident electron beam has a simple experimental layout and presents the full range of spatial and spectral information of the electron beams with energies of multi-hundred MeV level, despite the limited energy resolution of the simple electron spectrometer.

  10. Online beam energy measurement of Beijing electron positron collider II linear accelerator

    NASA Astrophysics Data System (ADS)

    Wang, S.; Iqbal, M.; Liu, R.; Chi, Y.

    2016-02-01

    This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

  11. How to measure energy of LEReC electron beam with magnetic spectrometer

    SciTech Connect

    Seletskiy, S.

    2016-04-11

    For successful cooling the energies of RHIC ion beam and LEReC electron beam must be matched with 10-4 accuracy. While the energy of ions will be known with required accuracy, e-beam energy can have as large initial offset as 5%. The final setting of e-beam energy will be performed by observing either Schottky spectrum or recombination signal from debunched ions co-traveling with the e-beam. Yet, to start observing such signals one has to set absolute energy of electron beam with accuracy better than 10-2, preferably better than 5∙10-3. The aim of this exercise is to determine whether and how such accuracy can be reached by utilizing LEReC 180° bend as a spectrometer.

  12. Dependence of the electron-cloud instability on the beam energy.

    PubMed

    Rumolo, G; Arduini, G; Métral, E; Shaposhnikova, E; Benedetto, E; Calaga, R; Papotti, G; Salvant, B

    2008-04-11

    The electron cloud (EC) can be formed in the beam pipe of a circular accelerator if the secondary emission yield (SEY) of the inner surface is larger than 1, and it can detrimentally affect the circulating beam. Understanding the underlying physics and defining the scaling laws of this effect is indispensable to steer the upgrade plans of the existing machines and the design of new ones. The single bunch EC instability (ECI) is shown to be strongly affected by the transverse beam size. Transversely, smaller beams going through an electron cloud generate higher electron peak densities and lower the intensity threshold to make the beam unstable. In particular, since higher energy beams have smaller transverse sizes (for equal normalized transverse emittances), the scaling of the ECI threshold with the beam energy turns out to be surprisingly unfavorable.

  13. The effect of energy deposition on pattern resolution in electron beam lithography

    NASA Astrophysics Data System (ADS)

    Raghunathan, Ananthan

    Electron beam lithography is one of the most important tools for nanofabrication. Electron beam lithography has consistently been able to offer higher resolution, typically better than 10 nm or so, compared to other techniques. In this work the contribution of electron-substrate interaction to pattern resolution is investigated. In electron beam lithography the incident beam is scattered in the resist-substrate stack by a combination of elastic and inelastic events which is described by the point spread function. Using a Vistec VB300 Gaussian beam lithography tool operating at 100 keV the experimental point spread function is investigated by a technique called point exposure distribution measurements. The experimental results indicate that the scattering in the sub-100 nm range shows several orders of the magnitude difference with that obtained via Monte Carlo simulations. In high energy electron beam lithography where forward scattering in small, contribution of secondary electrons generated by the primary beam must be taken into account. The chemical change leading to resist exposure is through bond scission, which is typically a low energy event between 3 -- 5 eV. Compared to the primary beam, the secondary electrons have a significantly higher probability of scission due to their lower energy. These secondary electrons are also generated with large emission angles and can travel several nanometers, leading to an increase in observed line widths compared to the size of the beam. An analytical model developed here, that considers the energy deposited by the secondary electrons, is able to predict the dependence of dose on observed diameter to within a reasonable accuracy. This technique used in conjunction with the knowledge of resist contrast is also indicative of pattern resolution limits in high energy electron beam lithography. It is also found that for negative resists, backscatter effects and resist contrast significantly degrade the resolution for large

  14. Studies of slow-positron production using low-energy primary electron beams.

    SciTech Connect

    Lessner, E.

    1999-04-20

    Slow-positron beams produced from negative-work-function solid-state moderators have found numerous applications in condensed matter physics. There are potential advantages in using low-energy primary electron beams for positron production, including reduced radiation damage to single-crystal moderators and reduced activation of nearby components. We present numerical calculations of positron yields and other beam parameters for various target-moderator configurations using the Argonne Wakefield Accelerator (AWA) [1] and Advanced Photon Source (APS) [2] electron linacs [3] as examples of sources for the primary electron beams. The status of experiments at these facilities is reviewed.

  15. Velocity dispersion of correlated energy spread electron beams in the free electron laser

    NASA Astrophysics Data System (ADS)

    Campbell, L. T.; Maier, A. R.

    2017-03-01

    The effects of a correlated linear energy/velocity chirp in the electron beam in the free electron laser (FEL), and how to compensate for its effects by using an appropriate taper (or reverse-taper) of the undulator magnetic field, is well known. The theory, as described thus far, ignores velocity dispersion from the chirp in the undulator, taking the limit of a ‘small’ chirp. In the following, the physics of compensating for chirp in the beam is revisited, including the effects of velocity dispersion, or beam compression or decompression, in the undulator. It is found that the limit of negligible velocity dispersion in the undulator is different from that previously identified as the small chirp limit, and is more significant than previously considered. The velocity dispersion requires a taper which is nonlinear to properly compensate for the effects of the detuning, and also results in a varying peak current (end thus a varying gain length) over the length of the undulator. The results may be especially significant for plasma driven FELs and low energy linac driven FEL test facilities.

  16. Experimental study of magnetically confined hollow electron beams in the Tevatron as collimators for intense high-energy hadron beams

    SciTech Connect

    Stancari, G.; Annala, G.; Shiltsev, V.; Still, D.; Valishev, A.; Vorobiev, L.; /Fermilab

    2011-03-01

    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 losses. 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 tested at Fermilab for this purpose. It was installed in one of the Tevatron electron lenses in the summer of 2010. We present the results of the first experimental tests of the hollow-beam collimation concept on 980-GeV antiproton bunches in the Tevatron.

  17. Precision shape modification of nanodevices with a low-energy electron beam

    DOEpatents

    Zettl, Alex; Yuzvinsky, Thomas David; Fennimore, Adam

    2010-03-09

    Methods of shape modifying a nanodevice by contacting it with a low-energy focused electron beam are disclosed here. In one embodiment, a nanodevice may be permanently reformed to a different geometry through an application of a deforming force and a low-energy focused electron beam. With the addition of an assist gas, material may be removed from the nanodevice through application of the low-energy focused electron beam. The independent methods of shape modification and material removal may be used either individually or simultaneously. Precision cuts with accuracies as high as 10 nm may be achieved through the use of precision low-energy Scanning Electron Microscope scan beams. These methods may be used in an automated system to produce nanodevices of very precise dimensions. These methods may be used to produce nanodevices of carbon-based, silicon-based, or other compositions by varying the assist gas.

  18. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    SciTech Connect

    Bakeman, M.S.; Van Tilborg, J.; Nakamura, K.; Gonsalves, A.; Osterhoff, J.; Sokollik, T.; Lin, C.; Robinson, K.E.; Schroeder, C.B.; Toth, Cs.; Weingartner, R.; Gruner, F.; Esarey, E.; Leemans, W.P.

    2010-06-01

    The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.

  19. High-energy Laser-accelerated Electron Beams for Long-range Interrogation

    SciTech Connect

    Cunningham, Nathaniel J.; Banerjee, Sudeep; Ramanathan, Vidya; Powers, Nathan; Chandler-Smith, Nate; Umstadter, Donald; Vane, Randy; Schultz, David; Beene, James; Pozzi, Sara; Clarke, Shaun

    2009-03-10

    We are studying the use of 0.1-1.0 GeV laser-accelerated electron beams as active interrogation probes for long-standoff radiography or nuclear activation of concealed special nuclear material. Use of beams in this energy range is largely unexplored, but such beams could provide notable advantages over lower-energy beams and x-rays. High-energy laser-accelerated electrons exhibit large penetration range through air and solids, and low beam divergence for both direct beams and secondary Bremsstrahlung x-rays. We present laboratory measurements of radiography and activation, using the high-power Diodes laser system at the University of Nebraska, as well as MCNP and GEANT Monte Carlo simulation results used to aid experiment design and interpretation.

  20. High-Energy Laser-Accelerated Electron Beams for Long-Range Interrogation

    SciTech Connect

    Cummingham, N. J.; Banerjee, Sudeep; Ramanathan, Vidya; Powell, Nathan; Chandler-Smith, Nate; Vane, C Randy; Schultz, David Robert; Pozzi, Sara; Clarke, Shaun; Beene, James R; Umstadter, Donald

    2009-01-01

    We are studying the use of 0.1 1.0 GeV laser-accelerated electron beams as active interrogation probes for long-standoff radiography or nuclear activation of concealed special nuclear material. Use of beams in this energy range is largely unexplored, but such beams could provide notable advantages over lower-energy beams and x-rays. High-energy laser-accelerated electrons exhibit large penetration range through air and solids, and low beam divergence for both direct beams and secondary Bremsstrahlung x-rays. We present laboratory measurements of radiography and activation, using the high-power Diodes laser system at the University of Nebraska, as well as MCNP and GEANT Monte Carlo simulation results used to aid experiment design and interpretation.

  1. Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

    NASA Astrophysics Data System (ADS)

    Yongfeng, DENG; Jian, JIANG; Xianwei, HAN; Chang, TAN; Jianguo, WEI

    2017-04-01

    The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.

  2. Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

    NASA Astrophysics Data System (ADS)

    Deng, Yongfeng; Jiang, Jian; Han, Xianwei; Tan, Chang; Wei, Jianguo

    2017-04-01

    The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.

  3. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    SciTech Connect

    Yedra, Ll.; Estradé, S.; Torruella, P.; Eljarrat, A.; Peiró, F.; Darbal, A. D.; Weiss, J. K.

    2014-08-04

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio.

  4. A very low energy compact electron beam ion trap for spectroscopic research in Shanghai.

    PubMed

    Xiao, J; Fei, Z; Yang, Y; Jin, X; Lu, D; Shen, Y; Liljeby, L; Hutton, R; Zou, Y

    2012-01-01

    In this paper, a new compact low energy electron beam ion trap, SH-PermEBIT, is reported. This electron beam ion trap (EBIT) can operate in the electron energy range of 60-5000 eV, with a current density of up to 100 A/cm(2). The low energy limit of this machine sets the record among the reported works so far. The magnetic field in the central drift tube region of this EBIT is around 0.5 T, produced by permanent magnets and soft iron. The design of this EBIT allows adjustment of the electron gun's axial position in the fringe field of the central magnetic field. This turned out to be very important for optimizing the magnetic field in the region of the electron gun and particularly important for low electron beam energy operation, since the magnetic field strength is not tunable with permanent magnets. In this work, transmission of the electron beam as well as the upper limit of the electron beam width under several conditions are measured. Spectral results from test operation of this EBIT at the electron energies of 60, 315, 2800, and 4100 eV are also reported.

  5. A very low energy compact electron beam ion trap for spectroscopic research in Shanghai

    NASA Astrophysics Data System (ADS)

    Xiao, J.; Fei, Z.; Yang, Y.; Jin, X.; Lu, D.; Shen, Y.; Liljeby, L.; Hutton, R.; Zou, Y.

    2012-01-01

    In this paper, a new compact low energy electron beam ion trap, SH-PermEBIT, is reported. This electron beam ion trap (EBIT) can operate in the electron energy range of 60-5000 eV, with a current density of up to 100 A/cm2. The low energy limit of this machine sets the record among the reported works so far. The magnetic field in the central drift tube region of this EBIT is around 0.5 T, produced by permanent magnets and soft iron. The design of this EBIT allows adjustment of the electron gun's axial position in the fringe field of the central magnetic field. This turned out to be very important for optimizing the magnetic field in the region of the electron gun and particularly important for low electron beam energy operation, since the magnetic field strength is not tunable with permanent magnets. In this work, transmission of the electron beam as well as the upper limit of the electron beam width under several conditions are measured. Spectral results from test operation of this EBIT at the electron energies of 60, 315, 2800, and 4100 eV are also reported.

  6. A very low energy compact electron beam ion trap for spectroscopic research in Shanghai

    SciTech Connect

    Xiao, J.; Fei, Z.; Yang, Y.; Jin, X.; Lu, D.; Shen, Y.; Hutton, R.; Zou, Y.; Liljeby, L.

    2012-01-15

    In this paper, a new compact low energy electron beam ion trap, SH-PermEBIT, is reported. This electron beam ion trap (EBIT) can operate in the electron energy range of 60-5000 eV, with a current density of up to 100 A/cm{sup 2}. The low energy limit of this machine sets the record among the reported works so far. The magnetic field in the central drift tube region of this EBIT is around 0.5 T, produced by permanent magnets and soft iron. The design of this EBIT allows adjustment of the electron gun's axial position in the fringe field of the central magnetic field. This turned out to be very important for optimizing the magnetic field in the region of the electron gun and particularly important for low electron beam energy operation, since the magnetic field strength is not tunable with permanent magnets. In this work, transmission of the electron beam as well as the upper limit of the electron beam width under several conditions are measured. Spectral results from test operation of this EBIT at the electron energies of 60, 315, 2800, and 4100 eV are also reported.

  7. Efficient Energy Deposition for an Electron Beam Pumped KrF Laser

    NASA Astrophysics Data System (ADS)

    Hegeler, F.; Myers, M. C.; Friedman, M.; Sethian, J. D.; Swanekamp, S. B.; Rose, D. V.; Welch, D. R.

    2002-11-01

    Electra is a repetitively pulsed, electron beam pumped krypton fluoride (KrF) laser that will develop the technologies that can meet the Inertial Fusion Energy (IFE) requirements for durability, efficiency, and cost. The Electra laser is pumped with two opposing electron beams each with parameters of 500 kV, 90 kA, with a 100 ns flat-top pulse duration, and a cathode area of 27 x 97 cm^2. The e-beam propagates through a hibachi structure, which supports a thin foil that isolates the vacuum diode from the high-pressure (>1 atm) laser gas. It has been demonstrated that segmenting the beam into strips to miss the hibachi support ribs significantly increases the electron beam deposition efficiency. The energy deposition efficiency is defined as the ratio of energy deposited in the laser gas over the vacuum diode e-beam energy. Energy deposition efficiencies of 75have been achieved with a 500 keV e-beam. In addition, 1-D and 3-D codes have simulated the e-beam propagation through the hibachi, and 1-D codes predict a maximum energy deposition efficiency of 81

  8. A diamond detector in the dosimetry of high-energy electron and photon beams.

    PubMed

    Laub, W U; Kaulich, T W; Nüsslin, F

    1999-09-01

    A diamond detector type 60003 (PTW Freiburg) was examined for the purpose of dosimetry with 4-20 MeV electron beams and 4-25 MV photon beams. Results were compared with those obtained by using a Markus chamber for electron beams and an ionization chamber for photon beams. Dose distributions were measured in a water phantom with the detector connected to a Unidos electrometer (PTW Freiburg). After a pre-irradiation of about 5 Gy the diamond detector shows a stability in response which is better than that of an ionization chamber. The current of the diamond detector was measured under variation of photon beam dose rate between 0.1 and 7 Gy min(-1). Different FSDs were chosen. Furthermore the pulse repetition frequency and the depth of the detector were changed. The electron beam dose rate was varied between 0.23 and 4.6 Gy min(-1) by changing the pulse-repetition frequency. The response shows no energy dependence within the covered photon-beam energy range. Between 4 MeV and 18 MeV electron beam energy it shows only a small energy dependence of about 2%, as expected from theory. For smaller electron energies the response increases significantly and an influence of the contact material used for the diamond detector can be surmised. A slight sublinearity of the current and dose rate was found. Detector current and dose rate are related by the expression i alpha Ddelta, where i is the detector current, D is the dose rate and delta is a correction factor of approximately 0.963. Depth-dose curves of photon beams, measured with the diamond detector, show a slight overestimation compared with measurements with the ionization chamber. This overestimation is compensated for by the above correction term. The superior spatial resolution of the diamond detector leads to minor deviations between depth-dose curves of electron beams measured with a Markus chamber and a diamond detector.

  9. Performance Studies of the Vibration Wire Monitor on the Test Stand with Low Energy Electron Beam

    NASA Astrophysics Data System (ADS)

    Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu

    In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic

  10. Parametric Channeling Radiation and its Application to the Measurement of Electron Beam Energy

    SciTech Connect

    Takabayashi, Y.

    2010-06-23

    We have proposed a method for observing parametric channeling radiation (PCR) and of applying it to the measurement of electron beam energy. The PCR process occurs if the energy of the channeling radiation coincides with the energy of the parametric X-ray radiation (PXR). The PCR process can be regarded as the diffraction of 'virtual channeling radiation'. We developed a scheme for beam energy measurement and designed an experimental setup. We also estimated the beam parameters, and calculated the angular distributions of PXR and PCR. These considerations indicate that the observation of PCR is promising.

  11. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question.

    PubMed

    Yang, X; Brunetti, E; Gil, D Reboredo; Welsh, G H; Li, F Y; Cipiccia, S; Ersfeld, B; Grant, D W; Grant, P A; Islam, M R; Tooley, M P; Vieux, G; Wiggins, S M; Sheng, Z M; Jaroszynski, D A

    2017-03-10

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  12. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    PubMed Central

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-01-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators. PMID:28281679

  13. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    NASA Astrophysics Data System (ADS)

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-03-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  14. High-energy-density electron beam generation in ultra intense laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Liu, Jianxun; Ma, Yanyun; Yang, Xiaohu; Zhao, Jun; Yu, Tongpu; Shao, Fuqiu; Zhuo, Hongbin; Gan, Longfei; Zhang, Guobo; Zhao, Yuan; Yang, Jingkang

    2017-01-01

    By using a two-dimensional particle-in-cell simulation, we demonstrate a scheme for high-energy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum (Al) target. With the laser having a peak intensity of 4 × 1023 W cm‑2, a high quality electron beam with a maximum density of 117nc and a kinetic energy density up to 8.79 × 1018 J m‑3 is generated. The temperature of the electron beam can be 416 MeV, and the beam divergence is only 7.25°. As the laser peak intensity increases (e.g., 1024 W cm‑2), both the beam energy density (3.56 × 1019 J m‑3) and the temperature (545 MeV) are increased, and the beam collimation is well controlled. The maximum density of the electron beam can even reach 180nc. Such beams should have potential applications in the areas of antiparticle generation, laboratory astrophysics, etc. This work is financially supported by the National Natural Science Foundation of China (Nos. 11475260, 11305264, 11622547, 91230205, and 11474360), the National Basic Research Program of China (No. 2013CBA01504), and the Research Project of NUDT (No. JC14-02-02).

  15. REFLEX: An energy deposition code that models the effects of electron reflection during electron beam heating tests

    SciTech Connect

    Stone, C.A. IV; Croessmann, C.D.; Whitley, J.B.

    1988-01-01

    This report describes an energy coupling model that considers electron reflection losses during electron beam heating experiments. This model is embodied on the REFLEX computer code, written in standard FORTRAN 77. REFLEX currently models energy deposition phenomena in three different sample geometries. These configurations include flat, cylindrical shell, and hemispherical shell surfaces. Given the electron beam operating parameters, REFLEX calculates the heat flux profile over a sample's surface, the total amount of energy deposited into a sample, and the percentage of the electron beam energy that is transferred to a sample. This document describes the energy deposition equations used in the REFLEX code; the program is described and detailed instructions are given regarding the input. Results are given for each geometry and possible experimental applications are presented. 3 refs., 20 figs., 11 tabs.

  16. The role of electronic energy loss in ion beam modification of materials

    DOE PAGES

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; ...

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less

  17. The role of electronic energy loss in ion beam modification of materials

    SciTech Connect

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.

  18. The applications of in situ electron energy loss spectroscopy to the study of electron beam nanofabrication.

    PubMed

    Chen, Shiahn J; Howitt, David G; Gierhart, Brian C; Smith, Rosemary L; Collins, Scott D

    2009-06-01

    An in situ electron energy loss spectroscopy (EELS) technique has been developed to investigate the dynamic processes associated with electron-beam nanofabrication on thin membranes. In this article, practical applications germane to e-beam nanofabrication are illustrated with a case study of the drilling of nanometer-sized pores in silicon nitride membranes. This technique involves successive acquisitions of the plasmon-loss and the core-level ionization-loss spectra in real time, both of which provide the information regarding the hole-drilling kinetics, including two respective rates for total mass loss, individual nitrogen and silicon element depletion, and the change of the atomic bonding environment. In addition, the in situ EELS also provides an alternative method for endpoint detection with a potentially higher time resolution than by imaging. On the basis of the time evolution of in situ EELS spectra, a qualitative working model combining knock-on sputtering, irradiation-induced mass transport, and phase separation can be proposed.

  19. Flue gases treatment by simultaneous use of electron beam and streams of microwave energy

    NASA Astrophysics Data System (ADS)

    Zimek, Z.; Chmielewski, A. G.; Bulka, S.; Lysov, G. W.; Artukh, I. G.; Frank, N. W.

    1995-09-01

    The experimental set up for investigation of SO2 and NOX removal from flue gases has been built on the base of electron accelerator and two independent microwave generators in Institute of Nuclear Chemistry and Technology. That allows to investigate a combined removal concept based on the simultaneous use the electron beam and streams of microwave energy to produce free radicals in reaction vessel. The preliminary experiment shows that is possible to find such condition with NH3 presence, where the efficiencies of the removal processes caused separately by electron beam and microwave energy are similar in described configuration of the experimental set up. The result of experiment where electron beam and microwave energy were used simultaneously indicates that total efficiency of the combined process is higher to compare with separate ones in certain experimental conditions.

  20. Study of Nonlinear QED Effects in Interactions of Terawatt Laser with High-Energy Electron Beam

    SciTech Connect

    Shmakov, K

    2003-11-06

    Nonlinear Compton scattering and electron-positron pair production have been observed in collisions of low-emittance 46.6 GeV electron beam with terawatt laser pulses from an Nd:glass laser at the experiment E144 at the Final Focus Test Beam at SLAC. In nonlinear Compton scattering up to four laser photons interact with an electron. The positrons are interpreted as arising from a two step process in which laser photons are backscattered to GeV energies by the electron beam followed by a collision between the high-energy photon and several laser photons to produce an electron-positron pair. These results are the first laboratory evidence for inelastic light-by-light scattering involving only real photons. Results are in agreement with theoretical calculations of strong-field QED.

  1. Anomalous electron heating and energy balance in an ion beam generated plasma

    SciTech Connect

    Guethlein, G.

    1987-04-01

    The plasma described in this report is generated by a 15 to 34 kV ion beam, consisting primarily of protons, passing through an H/sub 2/ gas cell neutralizer. Plasma ions (or ion-electron pairs) are produced by electron capture from (or ionization of) gas molecules by beam ions and atoms. An explanation is provided for the observed anomalous behavior of the electron temperature (T/sub e/): a step-lite, nearly two-fold jump in T/sub e/ as the beam current approaches that which minimizes beam angular divergence; insensitivity of T/sub e/ to gas pressure; and the linear relation of T/sub e/ to beam energy.

  2. Determination of electron energy, spectral width, and beam divergence at the exit window for clinical megavoltage x-ray beams.

    PubMed

    Sawkey, D L; Faddegon, B A

    2009-03-01

    Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were removed from the beam path, leaving only the exit window. With the x-ray target and flattener out of the beam, uncertainties in physical characteristics and relative position of the target and flattening filter, and in spot size, did not contribute to uncertainty in the energy. Beam current was lowered to reduce recombination effects. The measured dose distributions were compared with Monte Carlo simulation of the electron beam through the treatment head to extract the electron source characteristics. For the nominal 6 and 18 MV x-ray beams, the energies were 6.51 +/- 0.15 and 13.9 +/- 0.2 MeV, respectively, with the uncertainties resulting from uncertainties in the detector position in the measurement and in the stopping power in the simulations. Gaussian spectral distributions were used, with full widths at half maximum ranging from 20 +/- 4% at 6 MV to 13 +/- 4% at 18 MV required to match the fall-off portion of the percent-depth ionization curve. Profiles at the depth of maximum dose from simulations that used the manufacturer-specified exit window geometry and no beam divergence were 2-3 cm narrower than measured profiles. Two simulation configurations yielding the measured profile width were the manufacturer-specified exit window thickness with electron source divergences of 3.3 degrees at 6 MV and 1.8 degrees at 18 MV and an exit window 40% thicker than the manufacturer's specification with no beam divergence. With the x-ray target in place (and no flattener), comparison of measured to simulated profiles sets upper limits on the electron source divergences of 0.2 degrees at 6 MV and 0.1 degrees at 18 MV. A method of determining source

  3. Measurements of high-energy radiation generation from laser-wakefield accelerated electron beams

    SciTech Connect

    Schumaker, W. Vargas, M.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Maksimchuk, A.; Nees, J.; Yanovsky, V.; Thomas, A. G. R.; Krushelnick, K.; Sarri, G.; Dromey, B.; Zepf, M.

    2014-05-15

    Using high-energy (∼0.5 GeV) electron beams generated by laser wakefield acceleration (LWFA), bremsstrahlung radiation was created by interacting these beams with various solid targets. Secondary processes generate high-energy electrons, positrons, and neutrons, which can be measured shot-to-shot using magnetic spectrometers, short half-life activation, and Compton scattering. Presented here are proof-of-principle results from a high-resolution, high-energy gamma-ray spectrometer capable of single-shot operation, and high repetition rate activation diagnostics. We describe the techniques used in these measurements and their potential applications in diagnosing LWFA electron beams and measuring high-energy radiation from laser-plasma interactions.

  4. Energy constancy checking for electron beams using a wedge-shaped solid phantom combined with a beam profile scanner.

    PubMed

    Rosenow, U F; Islam, M K; Gaballa, H; Rashid, H

    1991-01-01

    An energy constancy checking method is presented which involves a specially designed wedge-shaped solid phantom in combination with a multiple channel ionization chamber array known as the Thebes device. Once the phantom/beam scanner combination is set up, measurements for all electron energies can be made and evaluated without re-entering the treatment room. This is also valid for the readjustment of beam energies which are found to deviate from required settings. The immediate presentation of the measurements is in the form of crossplots which resemble depth dose profiles. The evaluation of the measured data can be performed using a hand-held calculator, but processing of the measured signals through a PC-type computer is advisable. The method is insensitive to usual fluctuations in beam flatness. The sensitivity and reproducibility of the method are more than adequate. The method may also be used in modified form for photon beams.

  5. High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator

    DOE PAGES

    Sudar, N.; Musumeci, P.; Duris, J.; ...

    2016-10-19

    Here we present results of an experiment where, using a 200 GW CO2 laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.

  6. High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator

    NASA Astrophysics Data System (ADS)

    Sudar, N.; Musumeci, P.; Duris, J.; Gadjev, I.; Polyanskiy, M.; Pogorelsky, I.; Fedurin, M.; Swinson, C.; Kusche, K.; Babzien, M.; Gover, A.

    2016-10-01

    We present results of an experiment where, using a 200 GW CO2 laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.

  7. High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator.

    PubMed

    Sudar, N; Musumeci, P; Duris, J; Gadjev, I; Polyanskiy, M; Pogorelsky, I; Fedurin, M; Swinson, C; Kusche, K; Babzien, M; Gover, A

    2016-10-21

    We present results of an experiment where, using a 200 GW CO_{2} laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.

  8. High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator

    SciTech Connect

    Sudar, N.; Musumeci, P.; Duris, J.; Gadjev, I.; Polyanskiy, M.; Pogorelsky, I.; Fedurin, M.; Swinson, C.; Kusche, K.; Babzien, M.; Gover, A.

    2016-10-19

    Here we present results of an experiment where, using a 200 GW CO2 laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.

  9. Permanent-magnet energy spectrometer for electron beams from radiotherapy accelerators

    SciTech Connect

    McLaughlin, David J.; Shikhaliev, Polad M.; Matthews, Kenneth L.; Hogstrom, Kenneth R. Carver, Robert L.; Gibbons, John P.; Clarke, Taylor; Henderson, Alexander; Liang, Edison P.

    2015-09-15

    Purpose: The purpose of this work was to adapt a lightweight, permanent magnet electron energy spectrometer for the measurement of energy spectra of therapeutic electron beams. Methods: An irradiation geometry and measurement technique were developed for an approximately 0.54-T, permanent dipole magnet spectrometer to produce suitable latent images on computed radiography (CR) phosphor strips. Dual-pinhole electron collimators created a 0.318-cm diameter, approximately parallel beam incident on the spectrometer and an appropriate dose rate at the image plane (CR strip location). X-ray background in the latent image, reduced by a 7.62-cm thick lead block between the pinhole collimators, was removed using a fitting technique. Theoretical energy-dependent detector response functions (DRFs) were used in an iterative technique to transform CR strip net mean dose profiles into energy spectra on central axis at the entrance to the spectrometer. These spectra were transformed to spectra at 95-cm source to collimator distance (SCD) by correcting for the energy dependence of electron scatter. The spectrometer was calibrated by comparing peak mean positions in the net mean dose profiles, initially to peak mean energies determined from the practical range of central-axis percent depth-dose (%DD) curves, and then to peak mean energies that accounted for how the collimation modified the energy spectra (recalibration). The utility of the spectrometer was demonstrated by measuring the energy spectra for the seven electron beams (7–20 MeV) of an Elekta Infinity radiotherapy accelerator. Results: Plots of DRF illustrated their dependence on energy and position in the imaging plane. Approximately 15 iterations solved for the energy spectra at the spectrometer entrance from the measured net mean dose profiles. Transforming those spectra into ones at 95-cm SCD increased the low energy tail of the spectra, while correspondingly decreasing the peaks and shifting them to slightly lower

  10. Issues concerning high current lower energy electron beams required for ion cooling between EBIS LINAC and booster

    SciTech Connect

    Hershcovitch,A.

    2009-03-01

    Some issues, regarding a low energy high current electron beam that will be needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, are examined. Options for propagating such an electron beam, as well as the effect of neutralizing background plasma on electron and ion beam parameters are calculated. Computations and some experimental data indicate that none of these issues is a show stopper.

  11. Detection of electron beam energy variations using a computed radiography system.

    PubMed

    Cai, Yang C; Ge, Yuanyuan; Bernard, Damian; Turian, Julius; Chu, James C H

    2009-10-15

    A method to evaluate the electron beam energy constancy by employing the computed radiography (CR) system has been developed. In this method, a right triangular plastic wedge is used to produce a curve of the CR storage phosphor plate signal versus the wedge thickness. The curve, which resembles the percentage depth ionization curve of the clinical electron beams, can be used to derive the energy constancy metric EC(50). The sensitivity of the method was tested using polystyrene sheets of variable thicknesses. For electron energies up to 12 MeV, energy changes induced by 1.5 mm thick polystyrene can be detected, while a 2.3 mm thick polystyrene sheet is required for higher energies. The measurements were carried out over a two-year period. The results showed a good reproducibility with the use of the same CR plate and cassette, and without the requirement of calibration procedures. The two-year range of the EC(50) was within the 99% confidence intervals, and the standard deviation of the EC(50) was measured to be from 0.3 to 0.4 mm for different beam energies. This technique provides an efficient and accurate method to perform the electron beam energy check and could be used by centers equipped with the CR system without requiring additional detection devices.

  12. The optical band gap and surface free energy of polyethylene modified by electron beam irradiations

    NASA Astrophysics Data System (ADS)

    Abdul-Kader, A. M.

    2013-04-01

    In this study, investigations have been carried out on electron beam irradiated ultra high molecular weight polyethylene (UHMWPE). Polyethylene samples were irradiated with 1.5 MeV electron beam at doses ranging from 50 to 500 kGy. Modifications in optical properties and photoluminescence behavior of the polymer were evaluated by UV-vis and photoluminescence techniques. Changes of surface layer composition of UHMWPE produced by electron irradiations were studied by Rutherford back scattering spectrometry (RBS). The change in wettability and surface free energy induced by irradiations was also investigated. The optical absorption studies reveal that both optical band gap and Urbach's energy decreases with increasing electron dose. A correlation between energy gap and the number of carbon atoms in clusters is discussed. Photoluminescence spectra were reveal remarkable decrease in the integrated luminescence intensity with increasing irradiation dose. Contact angle measurements showed that wettability and surface free energy increases with increasing the irradiation dose.

  13. Energy deposition through radiative processes in absorbers irradiated by electron beams

    NASA Astrophysics Data System (ADS)

    Tatsuo, Tabata; Pedro, Andreo; Kunihiko, Shinoda; Rinsuke, Ito

    1994-09-01

    The component of energy deposition due to radiative processes (bremsstrahlung component) in absorbers irradiated by electron beams has been computed together with the total energy deposition by using the ITS Monte Carlo system version 3.0. Plane-parallel electron beams with energies from 0.1 to 100 MeV have been assumed to be incident normally on the slab absorber, whose thickness is 2.5 times the continuous slowing-down approximation (csda) range of the incident electrons. Absorber materials considered are elemental solids with atomic numbers between 4 and 92 (Be, C, Al, Cu, Ag, Au and U). An analytic formula is given to express the depth profile of the bremsstrahlung component as a function of scaled depth (depth in units of the csda range), incident-electron energy and absorber atomic number. It is also applicable to compounds.

  14. Beam Line Design and Beam Physics Study of Energy Recovery Linac Free Electron Laser at Peking University

    SciTech Connect

    Wang, Guimei

    2011-12-31

    Energy recovering linac (ERL) offers an attractive alternative for generating intense beams of charged particles by approaching the operational efficiency of a storage ring while maintaining the superior beam quality typical of a linear accelerator. In ERLs, the decelerated beam cancels the beam loading effects of the accelerated beam with high repetition rate. Therefore, ERLs can, in principle, accelerate very high average currents with only modest amounts of RF power. So the efficiency of RF power to beam is much higher. Furthermore, the energy of beam to dump is lower, so it will reduce dump radiation. With the successful experiments in large maximum-to-injection energy ratio up to 51:1 and high power FEL up to 14kW, the use of ERL, especially combining with superconducting RF technology, provides a potentially powerful new paradigm for generation of the charged particle beams used in MW FEL, synchrotron radiation sources, high-energy electron cooling devices and so on. The 3+1/2 DC-SC photo injector and two 9cell TESLA superconducting cavity for IR SASE FEL in PKU provides a good platform to achieve high average FEL with Energy Recovery. The work of this thesis is on Beam line design and Beam dynamics study of Energy Recovery Linac Free Electron Laser for Peking University. It is the upgrade of PKU facility, which is under construction. With ERL, this facility can work in CW mode, so it can operate high average beam current without RF power constraint in main linac and generate high average FEL power. Moreover, it provides a test facility to study the key technology in ERL. System parameters are optimized for PKU ERL-FEL. The oscillation FEL output power is studied with different bunch charge, transverse emittance, bunch length and energy spread. The theory of optimal RF power and Q{sub ext} with ERL and without ERL is analyzed and applied to PKU injector and linac including microphonic effect. pace charge effect in the injector and merger is studied for beam

  15. An electron cyclotron resonance ion source based low energy ion beam platform

    SciTech Connect

    Sun, L. T.; Shang, Y.; Ma, B. H.; Zhang, X. Z.; Feng, Y. C.; Li, X. X.; Wang, H.; Guo, X. H.; Song, M. T.; Zhao, H. Y.; Zhang, Z. M.; Zhao, H. W.; Xie, D. Z.

    2008-02-15

    To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.

  16. The beam energy feedback system for Beijing electron positron collider II linac.

    PubMed

    Wang, S; Iqbal, M; Chi, Y; Liu, R; Huang, X

    2017-03-01

    A beam-energy feedback system has been developed for the injection linac to meet the beam quality needed for the Beijing electron positron collider II storage ring. This paper describes the implementation and commissioning of this system in detail. The system consists of an energy measurement unit, application software, and an actuator unit. A non-intersecting beam energy monitor was developed to allow real-time online energy adjustment. The beam energy adjustment is achieved by adjusting the output microwave phase of the RF power source station. The phase control mechanism has also been modified, and a new control method taking the return difference of the phase shifter into account is used to improve the system's performance. This system achieves the design aim and can adjust the beam center energy with a rate of 2 Hz. With the energy feedback system, the stability of the injection rate is better; the fluctuation range is reduced from 20 mA/min to 10 mA/min, while the stability of the beam center energy is maintained within ±0.1%.

  17. Considerable knock-on displacement of metal atoms under a low energy electron beam.

    PubMed

    Gu, Hengfei; Li, Geping; Liu, Chengze; Yuan, Fusen; Han, Fuzhou; Zhang, Lifeng; Wu, Songquan

    2017-03-15

    Under electron beam irradiation, knock-on atomic displacement is commonly thought to occur only when the incident electron energy is above the incident-energy threshold of the material in question. However, we report that when exposed to intense electrons at room temperature at a low incident energy of 30 keV, which is far below the theoretically predicted incident-energy threshold of zirconium, Zircaloy-4 (Zr-1.50Sn-0.25Fe-0.15Cr (wt.%)) surfaces can undergo considerable displacement damage. We demonstrate that electron beam irradiation of the bulk Zircaloy-4 surface resulted in a striking radiation effect that nanoscale precipitates within the surface layer gradually emerged and became clearly visible with increasing the irradiation time. Our transmission electron microscope (TEM) observations further reveal that electron beam irradiation of the thin-film Zircaly-4 surface caused the sputtering of surface α-Zr atoms, the nanoscale atomic restructuring in the α-Zr matrix, and the amorphization of precipitates. These results are the first direct evidences suggesting that displacement of metal atoms can be induced by a low incident electron energy below threshold. The presented way to irradiate may be extended to other materials aiming at producing appealing properties for applications in fields of nanotechnology, surface technology, and others.

  18. Energy regeneration model of self-consistent field of electron beams into electric power*

    NASA Astrophysics Data System (ADS)

    Kazmin, B. N.; Ryzhov, D. R.; Trifanov, I. V.; Snezhko, A. A.; Savelyeva, M. V.

    2016-04-01

    We consider physic-mathematical models of electric processes in electron beams, conversion of beam parameters into electric power values and their transformation into users’ electric power grid (onboard spacecraft network). We perform computer simulation validating high energy efficiency of the studied processes to be applied in the electric power technology to produce the power as well as electric power plants and propulsion installation in the spacecraft.

  19. Target, purging magnet and electron collector design for scanned high-energy photon beams

    NASA Astrophysics Data System (ADS)

    Svensson, Roger; Åsell, Mats; Näfstadius, Peder; Brahme, Anders

    1998-05-01

    A new method for producing very narrow and intense 50 MV bremsstrahlung beams with a half-width as low as 35 mm at a distance of 1 m from the target is presented. Such a beam is well suited for intensity modulation using scanned photon beams. An algorithm has been developed to minimize the width of the bremsstrahlung beam generated in a multilayer target by varying the individual layer thicknesses and atomic numbers under given constraints on the total target thickness and the mean energy of the transmitted electrons. Under such constraints the narrowest possible bremsstrahlung beam is obtained with a target composed of layers of monotonically increasing atomic number starting with the lowest possible value at the entrance side where the electrons impinge. It is also shown that the narrowest photon beam profile is associated with the highest possible forward photon yield. To be able to use the optimized target clinically it is desirable to be able to collect and stop all the electrons that are transmitted through the target. The electrons are most efficiently collected if they are kept close together, i.e. by minimizing the multiple scatter of the electrons and consequently the half-width of the generated bremsstrahlung beam. This is achieved by a thin low-atomic-number target. A dedicated electron stopper has been developed and integrated with the purging magnet. When the electron stopper is combined with a purging magnet, a primary photon collimator and a multileaf collimator, almost all of the transmitted electrons and their associated bremsstrahlung contamination can effectively be collected. The narrow photon beams from thin low-atomic-number targets have the additional advantage of producing the hardest and most penetrative photon spectrum possible, which is ideal for treating large deep-seated tumours.

  20. Target, purging magnet and electron collector design for scanned high-energy photon beams.

    PubMed

    Svensson, R; Asell, M; Näfstadius, P; Brahme, A

    1998-05-01

    A new method for producing very narrow and intense 50 MV bremsstrahlung beams with a half-width as low as 35 mm at a distance of 1 m from the target is presented. Such a beam is well suited for intensity modulation using scanned photon beams. An algorithm has been developed to minimize the width of the bremsstrahlung beam generated in a multilayer target by varying the individual layer thicknesses and atomic numbers under given constraints on the total target thickness and the mean energy of the transmitted electrons. Under such constraints the narrowest possible bremsstrahlung beam is obtained with a target composed of layers of monotonically increasing atomic number starting with the lowest possible value at the entrance side where the electrons impinge. It is also shown that the narrowest photon beam profile is associated with the highest possible forward photon yield. To be able to use the optimized target clinically it is desirable to be able to collect and stop all the electrons that are transmitted through the target. The electrons are most efficiently collected if they are kept close together, i.e. by minimizing the multiple scatter of the electrons and consequently the half-width of the generated bremsstrahlung beam. This is achieved by a thin low-atomic-number target. A dedicated electron stopper has been developed and integrated with the purging magnet. When the electron stopper is combined with a purging magnet, a primary photon collimator and a multileaf collimator, almost all of the transmitted electrons and their associated bremsstrahlung contamination can effectively be collected. The narrow photon beams from thin low-atomic-number targets have the additional advantage of producing the hardest and most penetrative photon spectrum possible, which is ideal for treating large deep-seated tumours.

  1. Beam dynamics performances and applications of a low-energy electron-beam magnetic bunch compressor

    NASA Astrophysics Data System (ADS)

    Prokop, C. R.; Piot, P.; Carlsten, B. E.; Church, M.

    2013-08-01

    Many front-end applications of electron linear accelerators rely on the production of temporally compressed bunches. The shortening of electron bunches is often realized with magnetic bunch compressors located in high-energy sections of accelerators. Magnetic compression is subject to collective effects including space charge and self interaction via coherent synchrotron radiation. In this paper we explore the application of magnetic compression to low-energy (˜40 MeV), high-charge (nC) electron bunches with low normalized transverse emittances (<5 μm).

  2. Compact compressive arc and beam switchyard for energy recovery linac-driven ultraviolet free electron lasers

    NASA Astrophysics Data System (ADS)

    Akkermans, J. A. G.; Di Mitri, S.; Douglas, D.; Setija, I. D.

    2017-08-01

    High gain free electron lasers (FELs) driven by high repetition rate recirculating accelerators have received considerable attention in the scientific and industrial communities in recent years. Cost-performance optimization of such facilities encourages limiting machine size and complexity, and a compact machine can be realized by combining bending and bunch length compression during the last stage of recirculation, just before lasing. The impact of coherent synchrotron radiation (CSR) on electron beam quality during compression can, however, limit FEL output power. When methods to counteract CSR are implemented, appropriate beam diagnostics become critical to ensure that the target beam parameters are met before lasing, as well as to guarantee reliable, predictable performance and rapid machine setup and recovery. This article describes a beam line for bunch compression and recirculation, and beam switchyard accessing a diagnostic line for EUV lasing at 1 GeV beam energy. The footprint is modest, with 12 m compressive arc diameter and ˜20 m diagnostic line length. The design limits beam quality degradation due to CSR both in the compressor and in the switchyard. Advantages and drawbacks of two switchyard lines providing, respectively, off-line and on-line measurements are discussed. The entire design is scalable to different beam energies and charges.

  3. Quality assurance of electron and photon beam energy using the BQ-CHECK phantom.

    PubMed

    Speight, Richard J; Esmail, Ashraf; Weston, Steve J

    2011-02-01

    The BQ-CHECK phantom (PTW Freiburg, Germany) has been designed to be used with a 2D ion chamber array to facilitate the quality assurance (QA) of electron and photon beam qualities (BQ). The BQ-CHECK phantom has three wedges covering the diagonal axes of the beam: two opposed aluminum wedges used to measure electron energy and a single copper wedge used to measure photon energy. The purpose of this work was to assess the suitability of the BQ-CHECK phantom for use in a routine QA program. A range of percentage depth dose (PDD) curves for two photon beams and four electron beams were measured using a MP3 plotting tank (PTW Freiburg). These beams were used to irradiate a STARCHECK array (PTW Freiburg) with and without the BQ-CHECK phantom on top of the array. For photons, the ratio of the signals from two chambers underneath the copper wedge was used as an effective TPR measurement (TPR(eff)) and, for electrons, the full width at half maximum of the profile (E(FWHM)) underneath the aluminum wedges was used as an electron energy constancy measurement. PDD measurements were compared with TPR(eff) and E(FWHM) to assess the sensitivity of the BQ-CHECK phantom. The clinical tolerances of TPReff were determined for 6 MV (0.634-0.649), and 10MV (0.683-0.692). For electrons, the clinical tolerances of EFWHM were determined for 6 MeV (94.8-103.4 mm), 8 MeV (105.5-114.0 mm), 10 MeV (125.4-133.9 mm) and 12 MeV (138.8-147.3 mm).Electron and photon energy metrics are presented which demonstrate that the BQ-CHECK phantom could be used to form part of an efficient routine monthly QA program. Acceptable beam quality limits for various nominal beam energies were established and at these limits, modified profiles were acquired using the STARCHECK array. From the modified profiles, E(FWHM) and TPR(eff) were determined for the electron and photon beams, respectively. It was demonstrated that both E(FWHM) and the TPR(eff) have a linear relationship with conventional beam quality metrics.

  4. High-Brightness High-Energy Electron Beams from a Laser Wakefield Accelerator via Energy Chirp Control

    NASA Astrophysics Data System (ADS)

    Wang, W. T.; Li, W. T.; Liu, J. S.; Zhang, Z. J.; Qi, R.; Yu, C. H.; Liu, J. Q.; Fang, M.; Qin, Z. Y.; Wang, C.; Xu, Y.; Wu, F. X.; Leng, Y. X.; Li, R. X.; Xu, Z. Z.

    2016-09-01

    By designing a structured gas density profile between the dual-stage gas jets to manipulate electron seeding and energy chirp reversal for compressing the energy spread, we have experimentally produced high-brightness high-energy electron beams from a cascaded laser wakefield accelerator with peak energies in the range of 200-600 MeV, 0.4%-1.2% rms energy spread, 10-80 pC charge, and ˜0.2 mrad rms divergence. The maximum six-dimensional brightness B6 D ,n is estimated as ˜6.5 ×1 015 A /m2/0.1 % , which is very close to the typical brightness of e beams from state-of-the-art linac drivers. These high-brightness high-energy e beams may lead to the realization of compact monoenergetic gamma-ray and intense coherent x-ray radiation sources.

  5. Effectiveness of high energy electron beam against spore forming bacteria and viruses in slurry

    NASA Astrophysics Data System (ADS)

    Skowron, Krzysztof; Paluszak, Zbigniew; Olszewska, Halina; Wieczorek, Magdalena; Zimek, Zbigniew; Śrutek, Mścisław

    2014-08-01

    The aim of this study was to evaluate the efficacy of high energy electron beam effect against the most resistant indicators - spore forming bacteria (Clostridium sporogenes) and viruses (BPV) - which may occur in slurry. The applied doses of electron beam were 0, 1, 2, 3, 5, 7, 10 and 12 kGy. The theoretic inactivating dose of high energy electron beam for Clostridium sporogenes spores calculated based on the polynomial curve equation was 11.62 kGy, and determined on the basis of regression line equation for BPV virus was equal 23.49 kGy. The obtained results showed a quite good effectiveness of irradiation in bacterial spores inactivation, whereas relatively poor against viruses.

  6. A diamond detector in the dosimetry of high-energy electron and photon beams

    NASA Astrophysics Data System (ADS)

    Laub, Wolfram U.; Kaulich, Theodor W.; Nüsslin, Fridtjof

    1999-09-01

    A diamond detector type 60003 (PTW Freiburg) was examined for the purpose of dosimetry with 4-20 MeV electron beams and 4-25 MV photon beams. Results were compared with those obtained by using a Markus chamber for electron beams and an ionization chamber for photon beams. Dose distributions were measured in a water phantom with the detector connected to a Unidos electrometer (PTW Freiburg). After a pre-irradiation of about 5 Gy the diamond detector shows a stability in response which is better than that of an ionization chamber. The current of the diamond detector was measured under variation of photon beam dose rate between 0.1 and 7 Gy min-1. Different FSDs were chosen. Furthermore the pulse repetition frequency and the depth of the detector were changed. The electron beam dose rate was varied between 0.23 and 4.6 Gy min-1 by changing the pulse-repetition frequency. The response shows no energy dependence within the covered photon-beam energy range. Between 4 MeV and 18 MeV electron beam energy it shows only a small energy dependence of about 2%, as expected from theory. For smaller electron energies the response increases significantly and an influence of the contact material used for the diamond detector can be surmised. A slight sublinearity of the current and dose rate was found. Detector current and dose rate are related by the expression ipropto(dotD)Delta, where i is the detector current, (dotD) is the dose rate and Delta is a correction factor of approximately 0.963. Depth-dose curves of photon beams, measured with the diamond detector, show a slight overestimation compared

  7. Characterization of a Fricke dosimeter at high energy photon and electron beams used in radiotherapy.

    PubMed

    Moussous, O; Khoudri, S; Benguerba, M

    2011-12-01

    The dosimetric features of the Fricke dosimeter in clinical linear accelerator beams are considered. Experimental data were obtained using various nominal energies 6 and 18 MV, 12 and 15 MeV, including the (60)Co γ-ray beam. The calibration of the dosimeters was performed using the ionization chamber as a reference dosimeter. Some general characteristics of Fricke dosimeter such as energy dependence, optical density (OD)-dose relationship, reproducibility, accuracy, dose rate dependence were analyzed. The Fricke solution shows linearity in OD-dose relationship, energy independence and a good reproducibility over the energy range investigated. The Fricke dosimeter was found to be suitable for carrying out absorbed dose to water measurements in the calibration of high energy electron and photon beams.

  8. Implementation of Radio-Frequency Deflecting Devices for Comprehensive High-Energy Electron Beam Diagnosis

    NASA Astrophysics Data System (ADS)

    Craievich, Paolo; Petronio, Marco; Biedron, Sandra G.; Castronovo, Davide; Dal Forno, Massimo; Di Mitri, Simone; Faure, Nicolas; La Civita, Daniele; Penco, Giuseppe; Rumiz, Luca; Sturari, Luca; Vescovo, Roberto; Wang, Defa

    2015-02-01

    In next-generation light sources, high-brightness electron beams are used in a free-electron laser configuration to produce light for use by scientists and engineers in numerous fields of research. High-brightness beams are described for such light sources as having low transverse and longitudinal emittances, high peak currents, and low slice emittance and energy spread. The optimal generation and preservation of such high-brightness electron beams during the acceleration process and propagation to and through the photon-producing element is imperative to the quality and performance of the light source. To understand the electron beam's phase space in the accelerating section of a next-generation light source machine, we employed radio-frequency cavities operating in a deflecting mode in conjunction with a magnetic spectrometer and imaging system for both low (250 MeV) and high (1.2 GeV) electron energies. This high-resolution, high-energy system is an essential diagnostic for the optimization and control of the electron beam in the FERMI light source generating fully transversely and longitudinally coherent light in the VUV to soft x-ray wavelength regimes. This device is located at the end of the linear accelerator in order to provide the longitudinal phase space nearest to the entrance of the photon-producing beam-lines. Here, we describe the design, fabrication, characterization, commissioning, and operational implementation of this transverse deflecting cavity structure diagnostic system for the high-energy (1.2 GeV) regime.

  9. A Monochromatic, Aberration-Corrected, Dual-Beam Low Energy Electron Microscope

    PubMed Central

    Mankos, Marian; Shadman, Khashayar

    2013-01-01

    The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. PMID:23582636

  10. The response of Kodak EDR2 film in high-energy electron beams.

    PubMed

    Gerbi, Bruce J; Dimitroyannis, Dimitri A

    2003-10-01

    Kodak XV2 film has been a key dosimeter in radiation therapy for many years. The advantages of the recently introduced Kodak EDR2 film for photon beam dosimetry have been the focus of several IMRT verification dosimetry publications. However, no description of this film's response to electron beams exists in the literature. We initiated a study to characterize the response and utility of this film for electron beam dosimetry. We exposed a series of EDR2 films to 6, 9, 12, 16, and 20 MeV electrons in addition to 6 and 18 MV x rays to develop standard characteristic curves. The linac was first calibrated to ensure that the delivered dose was known accurately. All irradiations were done at dmax in polystyrene for both photons and electrons, all films were from the same batch, and were developed at the same time. We also exposed the EDR2 films in a solid water phantom to produce central axis depth dose curves. These data were compared against percent depth dose curves measured in a water phantom using an IC-10 ion chamber, Kodak XV2 film, and a PTW electron diode. The response of this film was the same for both 6 and 18 MV x rays, but showed an apparent energy-dependent enhancement for electron beams. The response of the film also increased with increasing electron energy. This caused the percent depth dose curves using film to be shifted toward the surface compared to the ion chamber data.

  11. Generation of a pulsed low-energy electron beam using the channel spark device

    SciTech Connect

    Elgarhy, M. A. I. Hassaballa, S. E.; Rashed, U. M.; ElSabbagh, M. M.; Saudy, A. H.; Soliman, H. M.

    2015-12-15

    For the generation of low-energy electron beam, the design and characteristics of channel spark discharge (CSD) operating at a low voltage are presented in this paper. The discharge voltage, discharge current, X-ray emissions, and electron beam current were experimentally determined. The effects of the applied voltage, working gas pressure, and external capacitance on the CSD and beam parameters were measured. At an applied voltage of 11 kV, an oxygen gas pressure of 25 mTorr, and an external capacitance of 16.45 nF, the maximum measured current was 900 A. The discharge current increased with the increase in the pressure and capacitance, while its periodic time decreased with the increase in the pressure. Two types of the discharge were identified and recorded: the hollow cathode discharge and the conduction discharge. A Faraday cup was used to measure the beam current. The maximum measured beam current was 120 A, and the beam signal exhibited two peaks. The increase in both the external capacitance and the applied discharge voltage increased the maximum electron beam current. The electron-beam pulse time decreased with the increase in the gas pressure at a constant voltage and increased with the decrease in the applied discharge voltage. At an applied voltage of 11 kV and an oxygen gas pressure of 15 mTorr, the maximum beam energy was 2.8 keV. The X-ray signal intensity decreased with the increase in the gas pressure and increased with the increase in the capacitance.

  12. Generation of a pulsed low-energy electron beam using the channel spark device.

    PubMed

    Elgarhy, M A I; Hassaballa, S E; Rashed, U M; ElSabbagh, M M; Soliman, H M; Saudy, A H

    2015-12-01

    For the generation of low-energy electron beam, the design and characteristics of channel spark discharge (CSD) operating at a low voltage are presented in this paper. The discharge voltage, discharge current, X-ray emissions, and electron beam current were experimentally determined. The effects of the applied voltage, working gas pressure, and external capacitance on the CSD and beam parameters were measured. At an applied voltage of 11 kV, an oxygen gas pressure of 25 mTorr, and an external capacitance of 16.45 nF, the maximum measured current was 900 A. The discharge current increased with the increase in the pressure and capacitance, while its periodic time decreased with the increase in the pressure. Two types of the discharge were identified and recorded: the hollow cathode discharge and the conduction discharge. A Faraday cup was used to measure the beam current. The maximum measured beam current was 120 A, and the beam signal exhibited two peaks. The increase in both the external capacitance and the applied discharge voltage increased the maximum electron beam current. The electron-beam pulse time decreased with the increase in the gas pressure at a constant voltage and increased with the decrease in the applied discharge voltage. At an applied voltage of 11 kV and an oxygen gas pressure of 15 mTorr, the maximum beam energy was 2.8 keV. The X-ray signal intensity decreased with the increase in the gas pressure and increased with the increase in the capacitance.

  13. Radiation hygienization of cattle and swine slurry with high energy electron beam

    NASA Astrophysics Data System (ADS)

    Skowron, Krzysztof; Olszewska, Halina; Paluszak, Zbigniew; Zimek, Zbigniew; Kałuska, Iwona; Skowron, Karolina Jadwiga

    2013-06-01

    The research was carried out to assess the efficiency of radiation hygienization of cattle and swine slurry of different density using the high energy electron beam based on the inactivation rate of Salmonella ssp, Escherichia coli, Enterococcus spp and Ascaris suum eggs. The experiment was conducted with use of the linear electron accelerator Elektronika 10/10 in Institute of Nuclear Chemistry and Technology in Warsaw. The inoculated slurry samples underwent hygienization with high energy electron beam of 1, 3, 5, 7 and 10 kGy. Numbers of reisolated bacteria were determined according to the MPN method, using typical microbiological media. Theoretical lethal doses, D90 doses and hygienization efficiency of high energy electron beam were determined. The theoretical lethal doses for all tested bacteria ranged from 3.63 to 8.84 kGy and for A. suum eggs from 4.07 to 5.83 kGy. Salmonella rods turned out to be the most sensitive and Enterococcus spp were the most resistant to electron beam hygienization. The effectiveness or radiation hygienization was lower in cattle than in swine slurry and in thick than in thin one. Also the species or even the serotype of bacteria determined the dose needed to inactivation of microorganisms.

  14. AREAL low energy electron beam applications in life and materials sciences

    NASA Astrophysics Data System (ADS)

    Tsakanov, V. M.; Aroutiounian, R. M.; Amatuni, G. A.; Aloyan, L. R.; Aslanyan, L. G.; Avagyan, V. Sh.; Babayan, N. S.; Buniatyan, V. V.; Dalyan, Y. B.; Davtyan, H. D.; Derdzyan, M. V.; Grigoryan, B. A.; Grigoryan, N. E.; Hakobyan, L. S.; Haroutyunian, S. G.; Harutiunyan, V. V.; Hovhannesyan, K. L.; Khachatryan, V. G.; Martirosyan, N. W.; Melikyan, G. S.; Petrosyan, A. G.; Petrosyan, V. H.; Sahakyan, A. A.; Sahakyan, V. V.; Sargsyan, A. A.; Simonyan, A. S.; Tatikyan, S. Sh.; Tsakanova, G. V.; Tsovyan, E.; Vardanyan, A. S.; Vardanyan, V. V.; Yeremyan, A. S.; Yeritsyan, H. N.; Zanyan, G. S.

    2016-09-01

    The AREAL laser-driven RF gun provides 2-5 MeV energy ultrashort electron pulses for experimental study in life and materials sciences. We report the first experimental results of the AREAL beam application in the study of molecular-genetic effects, silicon-dielectric structures, ferroelectric nanofilms, and single crystals for scintillators.

  15. Challenges of dosimetry of ultra-short pulsed very high energy electron beams.

    PubMed

    Subiel, Anna; Moskvin, Vadim; Welsh, Gregor H; Cipiccia, Silvia; Reboredo, David; DesRosiers, Colleen; Jaroszynski, Dino A

    2017-05-11

    Very high energy electrons (VHEE) in the range from 100 to 250MeV have the potential of becoming an alternative modality in radiotherapy because of their improved dosimetric properties compared with 6-20MV photons generated by clinical linear accelerators (LINACs). VHEE beams have characteristics unlike any other beams currently used for radiotherapy: femtosecond to picosecond duration electron bunches, which leads to very high dose per pulse, and energies that exceed that currently used in clinical applications. Dosimetry with conventional online detectors, such as ionization chambers or diodes, is a challenge due to non-negligible ion recombination effects taking place in the sensitive volumes of these detectors. FLUKA and Geant4 Monte Carlo (MC) codes have been employed to study the temporal and spectral evolution of ultrashort VHEE beams in a water phantom. These results are complemented by ion recombination measurements employing an IBA CC04 ionization chamber for a 165MeV VHEE beam. For comparison, ion recombination has also been measured using the same chamber with a conventional 20MeV electron beam. This work demonstrates that the IBA CC04 ionization chamber exhibits significant ion recombination and is therefore not suitable for dosimetry of ultrashort pulsed VHEE beams applying conventional correction factors. Further study is required to investigate the applicability of ion chambers in VHEE dosimetry. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Experimental assessment of out-of-field dose components in high energy electron beams used in external beam radiotherapy.

    PubMed

    M Alabdoaburas, Mohamad; Mege, Jean-Pierre; Chavaudra, Jean; Vũ Bezin, Jérémi; Veres, Atilla; De Vathaire, Florent; Lefkopoulos, Dimitri; Diallo, Ibrahima

    2015-11-08

    The purpose of this work was to experimentally investigate the out-of-field dose in a water phantom, with several high energy electron beams used in external beam radiotherapy (RT). The study was carried out for 6, 9, 12, and 18 MeV electron beams, on three different linear accelerators, each equipped with a specific applicator. Measurements were performed in a water phantom, at different depths, for different applicator sizes, and off-axis distances up to 70 cm from beam central axis (CAX). Thermoluminescent powder dosimeters (TLD-700) were used. For given cases, TLD measurements were compared to EBT3 films and parallel-plane ionization chamber measurements. Also, out-of-field doses at 10 cm depth, with and without applicator, were evaluated. With the Siemens applicators, a peak dose appears at about 12-15 cm out of the field edge, at 1 cm depth, for all field sizes and energies. For the Siemens Primus, with a 10 × 10 cm(²) applicator, this peak reaches 2.3%, 1%, 0.9% and 1.3% of the maximum central axis dose (Dmax) for 6, 9, 12 and 18 MeV electron beams, respectively. For the Siemens Oncor, with a 10 × 10 cm(²) applicator, this peak dose reaches 0.8%, 1%, 1.4%, and 1.6% of Dmax for 6, 9, 12, and 14 MeV, respectively, and these values increase with applicator size. For the Varian 2300C/D, the doses at 12.5 cm out of the field edge are 0.3%, 0.6%, 0.5%, and 1.1% of Dmax for 6, 9, 12, and 18 MeV, respectively, and increase with applicator size. No peak dose is evidenced for the Varian applicator for these energies. In summary, the out-of-field dose from electron beams increases with the beam energy and the applicator size, and decreases with the distance from the beam central axis and the depth in water. It also considerably depends on the applicator types. Our results can be of interest for the dose estimations delivered in healthy tissues outside the treatment field for the RT patient, as well as in studies exploring RT long-term effects.

  17. The effect of electron beams on cyclotron maser emission excited by lower-energy cutoffs

    NASA Astrophysics Data System (ADS)

    Zhao, G. Q.; Feng, H. Q.; Wu, D. J.

    2016-05-01

    Electron-cyclotron maser (ECM) is one of the most important emission mechanisms in astrophysics and can be excited efficiently by lower-energy cutoffs of power-law electrons. These non-thermal electrons probably propagate as a directed collimated beam along ambient magnetic fields. This paper investigates the ECM, in which the effect of electron beams is emphasized. Results show the dependence of emission properties of the ECM on the beam feature. The maximum growth rate of the extraordinary mode (X2) rapidly decreases as the beam momentum increases, while the growth rate of the ordinary mode (O1) changes slightly. In particular, the ordinary mode can overcome the extraordinary mode and becomes the fastest growth mode once the beam momentum is large enough. This research presents an extension of the conventional studies on ECM driven by lower-energy cutoffs and may be helpful to understand better the emission process of solar type I radio bursts, which are dominated by the ordinary mode emission.

  18. The effect of electron beams on cyclotron maser emission excited by lower-energy cutoffs

    SciTech Connect

    Zhao, G. Q.; Feng, H. Q.; Wu, D. J.

    2016-05-15

    Electron-cyclotron maser (ECM) is one of the most important emission mechanisms in astrophysics and can be excited efficiently by lower-energy cutoffs of power-law electrons. These non-thermal electrons probably propagate as a directed collimated beam along ambient magnetic fields. This paper investigates the ECM, in which the effect of electron beams is emphasized. Results show the dependence of emission properties of the ECM on the beam feature. The maximum growth rate of the extraordinary mode (X2) rapidly decreases as the beam momentum increases, while the growth rate of the ordinary mode (O1) changes slightly. In particular, the ordinary mode can overcome the extraordinary mode and becomes the fastest growth mode once the beam momentum is large enough. This research presents an extension of the conventional studies on ECM driven by lower-energy cutoffs and may be helpful to understand better the emission process of solar type I radio bursts, which are dominated by the ordinary mode emission.

  19. Monte Carlo dose calculation improvements for low energy electron beams using eMC.

    PubMed

    Fix, Michael K; Frei, Daniel; Volken, Werner; Neuenschwander, Hans; Born, Ernst J; Manser, Peter

    2010-08-21

    The electron Monte Carlo (eMC) dose calculation algorithm in Eclipse (Varian Medical Systems) is based on the macro MC method and is able to predict dose distributions for high energy electron beams with high accuracy. However, there are limitations for low energy electron beams. This work aims to improve the accuracy of the dose calculation using eMC for 4 and 6 MeV electron beams of Varian linear accelerators. Improvements implemented into the eMC include (1) improved determination of the initial electron energy spectrum by increased resolution of mono-energetic depth dose curves used during beam configuration; (2) inclusion of all the scrapers of the applicator in the beam model; (3) reduction of the maximum size of the sphere to be selected within the macro MC transport when the energy of the incident electron is below certain thresholds. The impact of these changes in eMC is investigated by comparing calculated dose distributions for 4 and 6 MeV electron beams at source to surface distance (SSD) of 100 and 110 cm with applicators ranging from 6 x 6 to 25 x 25 cm(2) of a Varian Clinac 2300C/D with the corresponding measurements. Dose differences between calculated and measured absolute depth dose curves are reduced from 6% to less than 1.5% for both energies and all applicators considered at SSD of 100 cm. Using the original eMC implementation, absolute dose profiles at depths of 1 cm, d(max) and R50 in water lead to dose differences of up to 8% for applicators larger than 15 x 15 cm(2) at SSD 100 cm. Those differences are now reduced to less than 2% for all dose profiles investigated when the improved version of eMC is used. At SSD of 110 cm the dose difference for the original eMC version is even more pronounced and can be larger than 10%. Those differences are reduced to within 2% or 2 mm with the improved version of eMC. In this work several enhancements were made in the eMC algorithm leading to significant improvements in the accuracy of the dose

  20. Electromagnetic dispersion characteristics of a high energy electron beam guided with an ion channel

    NASA Astrophysics Data System (ADS)

    Jixiong, Xiao; Zhong, Zeng; Zhijiang, Wang; Donghui, Xia; Changhai, Liu

    2017-02-01

    Taking self-fields into consideration, dispersion properties of two types of electromagnetic modes for a high energy electron beam guided with an ion channel are investigated by using the linear perturbation theory. The dependences of the dispersion frequencies of electromagnetic waves on the electron beam radius, betatron frequency and boundary current are revealed. It is found that the electron beam radius and betatron frequency have different influences on the electromagnetic waves dispersion behavior by compared with the previous works. As the boundary current is taken into account, the TM modes will have two branches and a low-frequency branch emerged as the new branch in strong ion channel case. This new branch has similar dispersion behavior to the betatron modes. For TE modes, there are two branches and they have different dispersion behaviors in strong ion channel case. However, in weak ion channel case, the dispersion behaviors for both of the low frequency and high frequency branches are similar.

  1. Energy deposition, heat flow, and rapid solidification during laser and electron beam irradiation of materials

    SciTech Connect

    White, C.W.; Aziz, M.J.

    1985-10-01

    The fundamentals of energy deposition, heat flow, and rapid solidification during energy deposition from lasers and electron beams is reviewed. Emphasis is placed on the deposition of energy from pulsed sources (10 to 100 ns pulse duration time) in order to achieve high heating and cooling rates (10/sup 8/ to 10/sup 10/ /sup 0/C/s) in the near surface region. The response of both metals and semiconductors to pulsed energy deposition is considered. Guidelines are presented for the choice of energy source, wavelength, and pulse duration time.

  2. Gafchromic EBT3 film dosimetry in electron beams - energy dependence and improved film read-out.

    PubMed

    Sipilä, Petri; Ojala, Jarkko; Kaijaluoto, Sampsa; Jokelainen, Ilkka; Kosunen, Antti

    2016-01-01

    For megavoltage photon radiation, the fundamental dosimetry characteristics of Gafchromic EBT3 film were determined in  60Co gamma ray beam with addition of experimental and Monte Carlo (MC)-simulated energy dependence of the film for 6 MV photon beam and 6 MeV, 9 MeV, 12 MeV, and 16 MeV electron beams in water phantom. For the film read-out, two phase correction of scanner sensitivity was applied: a matrix correction for scanning area and dose-dependent correction by iterative procedure. With these corrections, the uniformity of response can be improved to be within ±50 pixel values (PVs). To improve the read-out accuracy, a procedure with flipped film orientations was established. With the method, scanner uniformity can be improved further and dust particles, scratches and/or dirt on scanner glass can be detected and eliminated. Responses from red and green channels were averaged for read-out, which decreased the effect of noise present in values from separate channels. Since the signal level with the blue channel is considerably lower than with other channels, the signal variation due to different perturbation effects increases the noise level so that the blue channel is not recommended to be used for dose determination. However, the blue channel can be used for the detection of emulsion thickness variations for film quality evaluations with unexposed films. With electron beams ranging from 6 MeV to 16 MeV and at reference measurement conditions in water, the energy dependence of the EBT3 film is uniform within 0.5%, with uncertainties close to 1.6% (k=2). Including 6 MV photon beam and the electron beams mentioned, the energy dependence is within 1.1%. No notable differences were found between the experimental and MC-simulated responses, indicating negligible change in intrinsic energy dependence of the EBT3 film for 6 MV photon beam and 6 MeV-16 MeV electron beams. Based on the dosimetric characteristics of the EBT3 film, the read-out procedure established

  3. Gafchromic EBT3 film dosimetry in electron beams - energy dependence and improved film read-out.

    PubMed

    Sipilä, Petri; Ojala, Jarkko; Kaijaluoto, Sampsa; Jokelainen, Ilkka; Kosunen, Antti

    2016-01-08

    For megavoltage photon radiation, the fundamental dosimetry characteristics of Gafchromic EBT3 film were determined in 60Co gamma ray beam with addition of experimental and Monte Carlo (MC)-simulated energy dependence of the film for 6 MV photon beam and 6 MeV, 9 MeV, 12 MeV, and 16 MeV electron beams in water phantom. For the film read-out, two phase correction of scanner sensitivity was applied: a matrix correction for scanning area and dose-dependent correction by iterative procedure. With these corrections, the uniformity of response can be improved to be within ± 50 pixel values (PVs). To improve the read-out accuracy, a procedure with flipped film orientations was established. With the method, scanner uniformity can be improved further and dust particles, scratches and/or dirt on scan-ner glass can be detected and eliminated. Responses from red and green channels were averaged for read-out, which decreased the effect of noise present in values from separate channels. Since the signal level with the blue channel is considerably lower than with other channels, the signal variation due to different perturbation effects increases the noise level so that the blue channel is not recommended to be used for dose determination. However, the blue channel can be used for the detection of emulsion thickness variations for film quality evaluations with unexposed films. With electron beams ranging from 6 MeV to 16 MeV and at reference measurement conditions in water, the energy dependence of the EBT3 film is uniform within 0.5%, with uncertainties close to 1.6% (k = 2). Including 6 MV photon beam and the electron beams mentioned, the energy dependence is within 1.1%. No notable differences were found between the experimental and MC-simulated responses, indicating negligible change in intrinsic energy dependence of the EBT3 film for 6 MV photon beam and 6 MeV-16 MeV electron beams. Based on the dosimetric characteristics of the EBT3 film, the read-out procedure established

  4. Electron-Excited X-Ray Microanalysis at Low Beam Energy: Almost Always an Adventure!

    PubMed

    Newbury, Dale E; Ritchie, Nicholas W M

    2016-08-01

    Scanning electron microscopy with energy-dispersive spectrometry has been applied to the analysis of various materials at low-incident beam energies, E 0≤5 keV, using peak fitting and following the measured standards/matrix corrections protocol embedded in the National Institute of Standards and Technology Desktop Spectrum Analyzer-II analytical software engine. Low beam energy analysis provides improved spatial resolution laterally and in-depth. The lower beam energy restricts the atomic shells that can be ionized, reducing the number of X-ray peak families available to the analyst. At E 0=5 keV, all elements of the periodic table except H and He can be measured. As the beam energy is reduced below 5 keV, elements become inaccessible due to lack of excitation of useful characteristic X-ray peaks. The shallow sampling depth of low beam energy microanalysis makes the technique more sensitive to surface compositional modification due to formation of oxides and other reaction layers. Accurate and precise analysis is possible with the use of appropriate standards and by accumulating high count spectra of unknowns and standards (>1 million counts integrated from 0.1 keV to E 0).

  5. Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

    SciTech Connect

    Piot, Philippe

    2015-12-01

    Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

  6. Beam Stop for Electron Accelerator Beam Characterisation

    NASA Astrophysics Data System (ADS)

    Roach, Greg; Sharp, Vic; Tickner, James; Uher, Josef

    2009-08-01

    Electron linear accelerator applications involving the generation of hard X-rays frequently require accurate knowledge of the electron beam parameters. We developed a beam stop device which houses a tungsten Bremsstrahlung target and enables the electron beam current, energy and position to be monitored. The beam stop consisted of four plates. The first was a removable aluminium (Al) transmission plate. Then followed the tungsten target. Behind the target there were four Al quadrant plates for beam position measurement. The last plate was a thick Al back-stop block. Currents from the four quadrants and the back-stop were measured and the beam lateral position, energy and current were calculated. The beam stop device was optimised using Monte-Carlo simulation, manufactured (including custom-made electronics and software) in our laboratory and tested at the ARPANSA (Australian Radiation Protection and Nuclear Safety Agency) linear accelerator in Melbourne. The electron beam energy was determined with a precision of 60 keV at beam energies between 11 and 21 MeV and the lateral beam position was controlled with a precision of 200 mum. The relative changes of the beam current were monitored as well.

  7. Study of Collective Beam Effects in Energy Recovery Linac Driven Free Electron Lasers

    NASA Astrophysics Data System (ADS)

    Hall, Christpher C.

    Collective beam effects such as coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) can degrade the quality of high-energy electron beams used for applications such as free-electron lasers (FELs). The advent of energy recovery linac (ERL)-based FELs brings exciting possibilities for very high-average current FELs that can operate with greater efficiency. However, due to the structure of ERLs, they may be even more susceptible to CSR. It is therefore necessary that these collective beam effects be well understood if future ERL-based designs are to be successful. The Jefferson Laboratory ERL driven IR FEL provides an ideal test-bed for looking at how CSR impacts the electron beam. Due to its novel design we can easily test how CSR's impact on the beam varies as a function of compression within the machine. In this work we will look at measurements of both average energy loss and energy spectrum fragmentation as a function of bunch compression. These results are compared to particle tracking simulations including a 1D CSR model and, in general, good agreement is seen between simulation and measurement. Of particular interest is fragmentation of the energy spectrum that is observed due to CSR and LSC. We will also show how this fragmentation develops and how it can be mitigated through use of the sextupoles in the JLab FEL. Finally, a more complete 2D model is used to simulate CSR-beam interaction. Due to the parameters of the experiment it is expected that a 2D CSR model would yield different results than the 1D CSR model. However, excellent agreement is seen between the two CSR model results.

  8. Measurements of particle emission from discharge sites in Teflon irradiated by high energy electron beams

    NASA Technical Reports Server (NTRS)

    Hazelton, R. C.; Churchill, R. J.; Yadlowsky, E. J.

    1979-01-01

    Anomalous behavior of synchronous orbit satellites manifested by overall degradation of system performance and reduced operating life is associated with electrical discharges resulting from differential charging of the spacecraft surface by fluxes of high energy electrons. During a laboratory simulation silver-backed Teflon samples have been irradiated by electron beams having energies in the range 16-26 keV. Charged particles emitted from the resultant electrical discharges have been measured with a biased Faraday cup and retarding potential analyser. Measurements indicate the presence of two distinct fluxes of particles, the first being an early pulse (0-600ns) of high energy (about 7keV) electrons, while the second is a late pulse (1-5 microseconds) of low energy electrons (less than 1eV) and ions (70eV) leaving the discharge site as a quasi plasma. Calculations indicate an electrostatic field as the dominant accelerating mechanism for charged particles.

  9. Measurements of particle emission from discharge sites in Teflon irradiated by high energy electron beams

    NASA Technical Reports Server (NTRS)

    Hazelton, R. C.; Churchill, R. J.; Yadlowsky, E. J.

    1979-01-01

    Anomalous behavior of synchronous orbit satellites manifested by overall degradation of system performance and reduced operating life is associated with electrical discharges resulting from differential charging of the spacecraft surface by fluxes of high energy electrons. During a laboratory simulation silver-backed Teflon samples have been irradiated by electron beams having energies in the range 16-26 keV. Charged particles emitted from the resultant electrical discharges have been measured with a biased Faraday cup and retarding potential analyser. Measurements indicate the presence of two distinct fluxes of particles, the first being an early pulse (0-600ns) of high energy (about 7keV) electrons, while the second is a late pulse (1-5 microseconds) of low energy electrons (less than 1eV) and ions (70eV) leaving the discharge site as a quasi plasma. Calculations indicate an electrostatic field as the dominant accelerating mechanism for charged particles.

  10. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    NASA Astrophysics Data System (ADS)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL < 1 / (2 πωpe)) laser pulses drive highly nonlinear plasma waves which can trap ~ nC of electrons and accelerate them to ~GeV energies over ~cm lengths. These electron beams can then be converted by a high-Z target via bremsstrahlung into low-divergence (< 20 mrad) beams of high-energy (<600 MeV) photons and subsequently into positrons via the Bethe-Heitler process. By increasing the material thickness and Z, the resulting Ne+ /Ne- ratio can approach unity, resulting in a near neutral density plasma jet. These quasi-neutral beams are presumed to retain the short-pulse (τL < 40 fs) characteristic of the electron beam, resulting in a high peak density of ne- /e+ ~ 1016 cm-3 , making the source an excellent candidate for laboratory study of astrophysical leptonic jets. Alternatively, the electron beam can be interacted with a counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  11. Evaluation of potential induced radioactivity in medical products as a function of electron energy in electron beam sterilization

    NASA Astrophysics Data System (ADS)

    Smith, Mark A.

    2012-01-01

    Commercial sterilization of medical devices may be performed using electron beam irradiators at various electron energies. The potential for activating components of the devices has been discussed, with current standards stating that electron energy greater than 10 MeV requires assessment of potential induced radioactivity. This paper evaluates the potential for induced activity in medical products sterilized in electron beam as a function of the electron maximum energy. Monte Carlo simulation of a surrogate medical device was used to calculate photon and neutron fields resulting from electron irradiation, which were used to calculate concentrations for several radionuclides. The experiments confirmed that 10 MeV is a conservative assumption for limiting induced radioactivity. However, under the conditions as evaluated, which is a limited total quantity of metal in the material being irradiated and absent a limited number of elements; the amount of induced activity at 12 MeV could also be considered insignificant. The comparison of the sum-of-fractions to the US Nuclear Regulatory Commission exempt concentration limits is less than unity for all energies below 12.1 MeV, which suggests that there is minimal probability of significant induced activity at energies above the 10 MeV upper energy limit.

  12. Simulation studies for operating electron beam ion trap at very low energy for disentangling edge plasma spectra

    SciTech Connect

    Jin Xuelong; Fei Zejie; Xiao Jun; Lu Di; Hutton, Roger; Zou Yaming

    2012-07-15

    Electron beam ion traps (EBITs) are very useful tools for disentanglement studies of atomic processes in plasmas. In order to assist studies on edge plasma spectroscopic diagnostics, a very low energy EBIT, SH-PermEBIT, has been set up at the Shanghai EBIT lab. In this work, simulation studies for factors which hinder an EBIT to operate at very low electron energies were made based on the Tricomp (Field Precision) codes. Longitudinal, transversal, and total kinetic energy distributions were analyzed for all the electron trajectories. Influences from the electron current and electron energy on the energy depression caused by the space charge are discussed. The simulation results show that although the energy depression is most serious along the center of the electron beam, the electrons in the outer part of the beam are more likely to be lost when an EBIT is running at very low energy. Using the simulation results to guide us, we successfully managed to reach the minimum electron beam energy of 60 eV with a beam transmission above 57% for the SH-PermEBIT. Ar and W spectra were measured from the SH-PermEBIT at the apparent electron beam energies (read from the voltage difference between the electron gun cathode and the central drift tube) of 60 eV and 1200 eV, respectively. The spectra are shown in this paper.

  13. Direct nanopatterning of polymer/silver nanoblocks under low energy electron beam irradiation.

    PubMed

    El Mel, Abdel-Aziz; Stephant, Nicolas; Gautier, Romain

    2016-10-06

    In this communication, we report on the growth, direct writing and nanopatterning of polymer/silver nanoblocks under low energy electron beam irradiation using a scanning electron microscope. The nanoblocks are produced by placing a droplet of an ethylene glycol solution containing silver nitrate and polyvinylpyrrolidone diluted in ethanol directly on a hot substrate heated up to 150 °C. Upon complete evaporation of the droplet, nanospheres, nano- and micro-triangles and nanoblocks made of silver-containing polymers, form over the substrate surface. Considering the nanoblocks as a model system, we demonstrate that such nanostructures are extremely sensitive to the e-beam extracted from the source of a scanning electron microscope operating at low acceleration voltages (between 5 and 7 kV). This sensitivity allows us to efficiently create various nanopatterns (e.g. arrays of holes, oblique slits and nanotrenches) in the material under e-beam irradiation. In addition to the possibility of writing, the nanoblocks revealed a self-healing ability allowing them to recover a relatively smooth surface after etching. Thanks to these properties, such nanomaterials can be used as a support for data writing and erasing on the nanoscale under low energy electron beam irradiation.

  14. Electron beam energy chirp control with a rectangular corrugated structure at the Linac Coherent Light Source

    DOE PAGES

    Zhang, Zhen; Bane, Karl; Ding, Yuantao; ...

    2015-01-30

    In this study, electron beam energy chirp is an important parameter that affects the bandwidth and performance of a linac-based, free-electron laser. In this paper we study the wakefields generated by a beam passing between at metallic plates with small corrugations, and then apply such a device as a passive dechirper for the Linac Coherent Light Source (LCLS) energy chirp control with a multi-GeV and femtosecond electron beam. Similar devices have been tested in several places at relatively low energies (~100 MeV) and with relatively long bunches (> 1ps). In the parameter regime of the LCLS dechirper, with the corrugationmore » size similar to the gap between the plates, the analytical solutions of the wakefields are no longer applicable, and we resort to a field matching program to obtain the wakes. Based on the numerical calculations, we fit the short-range, longitudinal wakes to simple formulas, valid over a large, useful parameter range. Finally, since the transverse wakefields - both dipole and quadrupole-are strong, we compute and include them in beam dynamics simulations to investigate the error tolerances when this device is introduced in the LCLS.« less

  15. Electron-beam-pumped XeF(C->A) laser energy scaling

    NASA Astrophysics Data System (ADS)

    Litzenberger, Leonard N.; Smith, M. James; Pardue, Albert L., Jr.; Jones, R. W.; Stone, David

    1995-04-01

    The pulse output energy of the electron-beam pumped XeF(C->A) laser system has been increased by nearly two orders of magnitude relative to previously demonstrated values, to 170 J. This performance was achieved in an existing laser device, referred to as Scale-Up, which is pumped by a pair of three meter long, counterpropagating electron beams. The device was equipped with subaperture mirrors which were coated to be reflective in the blue-green portion of the visible spectrum. The reflectivity of the output coupler of the folded stable cavity was carefully selected to maximize the laser output energy. This choice involved a trade-off between the amount of time required for the intracavity flux to build up from noise to the saturation level, and the energy extraction efficiency under steady state oscillating conditions. The observed optical pulse duration of 0.8 microsecond(s) was in good agreement with the prediction of a flux buildup model which was developed during the design phase of this effort. The demonstrated specific output energy of 1.7 J/L was comparable to that previously achieved in small scale lasing tests which were also performed under free-running conditions. This proved that the XeF(C->A) laser system is volumetrically scalable to high output energy per pulse. No evidence of laser oscillation on the competing XeF(B->X) transition was observed. The pulse-average electron-beam pump rate was 140 kW/cm3, and the electron-beam pulse duration was 1.7 microsecond(s) . The ability to operate this low gain laser system at a moderate pump rate greatly relaxes the constraints on the design of the electron gun and pulse power subsystems, making construction of a high average power laser device possible.

  16. The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors.

    PubMed

    Thorman, Rachel M; Kumar T P, Ragesh; Fairbrother, D Howard; Ingólfsson, Oddur

    2015-01-01

    Focused electron beam induced deposition (FEBID) is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (<100 eV) secondary electrons generated by interactions of the primary beam with the substrate. These low-energy electrons are abundant both inside and outside the area of the primary electron beam and are associated with reactions causing incomplete ligand dissociation from FEBID precursors. As it is not possible to directly study the effects of secondary electrons in situ in FEBID, other means must be used to elucidate their role. In this context, gas phase studies can obtain well-resolved information on low-energy electron-induced reactions with FEBID precursors by studying isolated molecules interacting with single electrons of well-defined energy. In contrast, ultra-high vacuum surface studies on adsorbed precursor molecules can provide information on surface speciation and identify species desorbing from a substrate during electron irradiation under conditions more representative of FEBID. Comparing gas phase and surface science studies allows for insight into the primary deposition mechanisms for individual precursors; ideally, this information can be used to design future FEBID precursors and optimize deposition conditions. In this review, we give a summary of different low-energy electron-induced fragmentation processes that can be initiated by the secondary electrons generated in FEBID, specifically, dissociative electron attachment, dissociative ionization, neutral dissociation, and dipolar dissociation, emphasizing the different

  17. The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors

    PubMed Central

    Thorman, Rachel M; Kumar T. P., Ragesh; Fairbrother, D Howard

    2015-01-01

    Summary Focused electron beam induced deposition (FEBID) is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (<100 eV) secondary electrons generated by interactions of the primary beam with the substrate. These low-energy electrons are abundant both inside and outside the area of the primary electron beam and are associated with reactions causing incomplete ligand dissociation from FEBID precursors. As it is not possible to directly study the effects of secondary electrons in situ in FEBID, other means must be used to elucidate their role. In this context, gas phase studies can obtain well-resolved information on low-energy electron-induced reactions with FEBID precursors by studying isolated molecules interacting with single electrons of well-defined energy. In contrast, ultra-high vacuum surface studies on adsorbed precursor molecules can provide information on surface speciation and identify species desorbing from a substrate during electron irradiation under conditions more representative of FEBID. Comparing gas phase and surface science studies allows for insight into the primary deposition mechanisms for individual precursors; ideally, this information can be used to design future FEBID precursors and optimize deposition conditions. In this review, we give a summary of different low-energy electron-induced fragmentation processes that can be initiated by the secondary electrons generated in FEBID, specifically, dissociative electron attachment, dissociative ionization, neutral dissociation, and dipolar dissociation, emphasizing the

  18. Brilliant GeV electron beam with narrow energy spread generated by a laser plasma accelerator

    NASA Astrophysics Data System (ADS)

    Hu, Ronghao; Lu, Haiyang; Shou, Yinren; Lin, Chen; Zhuo, Hongbin; Chen, Chia-erh; Yan, Xueqing

    2016-09-01

    The production of GeV electron beam with narrow energy spread and high brightness is investigated using particle-in-cell simulations. A controlled electron injection scheme and a method for phase-space manipulation in a laser plasma accelerator are found to be essential. The injection is triggered by the evolution of two copropagating laser pulses near a sharp vacuum-plasma transition. The collection volume is well confined and the injected bunch is isolated in phase space. By tuning the parameters of the laser pulses, the parameters of the injected electron bunch, such as the bunch length, energy spread, emittance and charge, can be adjusted. Manipulating the phase-space rotation with the rephasing technique, the injected electron bunch can be accelerated to GeV level while keeping relative energy spread below 0.5% and transverse emittance below 1.0 μ m . The results present a very promising way to drive coherent x-ray sources.

  19. Physics of Neutralization of Intense High-Energy Ion Beam Pulses by Electrons

    SciTech Connect

    Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Lee, E. P.; Friedman, A.

    2010-04-28

    Neutralization and focusing of intense charged particle beam pulses by electrons forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self- magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

  20. Physics of neutralization of intense high-energy ion beam pulses by electrons

    SciTech Connect

    Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Lee, E. P.; Friedman, A.

    2010-05-15

    Neutralization and focusing of intense charged particle beam pulses by electrons form the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100 G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

  1. Evaluation of low energy electron beam dose application by means of a portable optical device

    NASA Astrophysics Data System (ADS)

    Reitzig, Manuela; Winkler, Martin; Härtling, Thomas; Röder, Olaf; Opitz, Jörg

    2014-11-01

    We present our recent development concerning the evaluation of a low energy dose application to electron beam responding materials with a simple portable optical device. Electron beam irradiation is a promising option to sterilize sensitive and high performance products or surfaces at a low temperature and without moisture. Especially in the fields of the food industry and medicine, regulations regarding sterility are increasingly tightened. Because of this, a secure proof for electron-beam-assisted sterilization is required. However, no nondestructive and in situ method exists up until now. Our approach to provide a secure proof of sterilization is to place a suitable marker material based on rare-earth-doped phosphors inside or on the top of the packaging material of the respective product. Upon electron irradiation the marker material changes its luminescence properties as a function of the applied energy dose. We verified the energy dependence by means of time-resolved measurements of the luminescence decay of an upconversion phosphor with a portable optical device. In our experimental realization, short laser pulses in the near-infrared range are triggered by a microcontrol unit (MCU) and excite the marker material. The light emitted by the marker is collected in the range between 400 and 1100 nm via a silicon photodiode, processed by the MCU, and analyzed in a Labview program via a single-exponential fit. As a main result, we observe an increasing reduction of the luminescence lifetime with higher dose applications.

  2. 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.

  3. 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.

  4. A Method to Improve Electron Density Measurement of Cone-Beam CT Using Dual Energy Technique

    PubMed Central

    Men, Kuo; Dai, Jian-Rong; Li, Ming-Hui; Chen, Xin-Yuan; Zhang, Ke; Tian, Yuan; Huang, Peng; Xu, Ying-Jie

    2015-01-01

    Purpose. To develop a dual energy imaging method to improve the accuracy of electron density measurement with a cone-beam CT (CBCT) device. Materials and Methods. The imaging system is the XVI CBCT system on Elekta Synergy linac. Projection data were acquired with the high and low energy X-ray, respectively, to set up a basis material decomposition model. Virtual phantom simulation and phantoms experiments were carried out for quantitative evaluation of the method. Phantoms were also scanned twice with the high and low energy X-ray, respectively. The data were decomposed into projections of the two basis material coefficients according to the model set up earlier. The two sets of decomposed projections were used to reconstruct CBCT images of the basis material coefficients. Then, the images of electron densities were calculated with these CBCT images. Results. The difference between the calculated and theoretical values was within 2% and the correlation coefficient of them was about 1.0. The dual energy imaging method obtained more accurate electron density values and reduced the beam hardening artifacts obviously. Conclusion. A novel dual energy CBCT imaging method to calculate the electron densities was developed. It can acquire more accurate values and provide a platform potentially for dose calculation. PMID:26346510

  5. Energy monitoring device for 1.5-2.4 MeV electron beams

    NASA Astrophysics Data System (ADS)

    Fuochi, P. G.; Lavalle, M.; Martelli, A.; Kovács, A.; Mehta, K.; Kuntz, F.; Plumeri, S.

    2010-03-01

    An easy-to-use and robust energy monitoring device has been developed for reliable detection of day-to-day small variations in the electron beam energy, a critical parameter for quality control and quality assurance in industrial radiation processing. It has potential for using on-line, thus providing real-time information. Its working principle is based on the measurement of currents, or charges, collected by two aluminium absorbers of specific thicknesses (dependent on the beam energy), insulated from each other and positioned within a faraday cup-style aluminium cage connected to the ground. The device has been extensively tested in the energy range of 4-12 MeV under standard laboratory conditions at Institute of Isotopes and CNR-ISOF using different types of electron accelerators; namely, a TESLA LPR-4 LINAC (3-6 MeV) and a L-band Vickers LINAC (7-12 MeV), respectively. This device has been also tested in high power electron beam radiation processing facilities, one equipped with a 7-MeV LUE-8 linear accelerator used for crosslinking of cables and medical device sterilization, and the other equipped with a 10 MeV Rhodotron TT100 recirculating accelerator used for in-house sterilization of medical devices. In the present work, we have extended the application of this method to still lower energy region, i.e. from 1.5 to 2.4 MeV. Also, we show that such a device is capable of detecting deviation in the beam energy as small as 40 keV.

  6. AAPM's TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams.

    PubMed

    Almond, P R; Biggs, P J; Coursey, B M; Hanson, W F; Huq, M S; Nath, R; Rogers, D W

    1999-09-01

    A protocol is prescribed for clinical reference dosimetry of external beam radiation therapy using photon beams with nominal energies between 60Co and 50 MV and electron beams with nominal energies between 4 and 50 MeV. The protocol was written by Task Group 51 (TG-51) of the Radiation Therapy Committee of the American Association of Physicists in Medicine (AAPM) and has been formally approved by the AAPM for clinical use. The protocol uses ion chambers with absorbed-dose-to-water calibration factors, N(60Co)D,w which are traceable to national primary standards, and the equation D(Q)w = MkQN(60Co)D,w where Q is the beam quality of the clinical beam, D(Q)w is the absorbed dose to water at the point of measurement of the ion chamber placed under reference conditions, M is the fully corrected ion chamber reading, and kQ is the quality conversion factor which converts the calibration factor for a 60Co beam to that for a beam of quality Q. Values of kQ are presented as a function of Q for many ion chambers. The value of M is given by M = PionP(TP)PelecPpolMraw, where Mraw is the raw, uncorrected ion chamber reading and Pion corrects for ion recombination, P(TP) for temperature and pressure variations, Pelec for inaccuracy of the electrometer if calibrated separately, and Ppol for chamber polarity effects. Beam quality, Q, is specified (i) for photon beams, by %dd(10)x, the photon component of the percentage depth dose at 10 cm depth for a field size of 10x10 cm2 on the surface of a phantom at an SSD of 100 cm and (ii) for electron beams, by R50, the depth at which the absorbed-dose falls to 50% of the maximum dose in a beam with field size > or =10x10 cm2 on the surface of the phantom (> or =20x20 cm2 for R50>8.5 cm) at an SSD of 100 cm. R50 is determined directly from the measured value of I50, the depth at which the ionization falls to 50% of its maximum value. All clinical reference dosimetry is performed in a water phantom. The reference depth for calibration

  7. Determination of the displacement energy of O, Si and Zr under electron beam irradiation

    SciTech Connect

    Edmondson, Philip D; Weber, William J; Namavar, Fereydoon; Zhang, Yanwen

    2012-01-01

    The response of nanocrystalline, stabilizer-free cubic zirconia thin films on a Si substrate to electron beam irradiation with energies of 4, 110 and 200 keV and fluences up to {approx}1.5 x 10{sup 22} e m{sup -2} has been studied to determine the displacement energies. The 110 and 200 keV irradiations were performed in situ using a transmission electron microscope; the 4 keV irradiations were performed ex situ using an electron gun. In all three irradiations, no structural modification of the zirconia was observed, despite the high fluxes and fluences. However the Si substrate on which the zirconia film was deposited was amorphized under the 200 keV electron irradiation. Examination of the electron-solid interactions reveals that the kinetic energy transfer from the 200 keV electrons to the silicon lattice is sufficient to cause atomic displacements, resulting in amorphization. The kinetic energy transfer from the 200 keV electrons to the oxygen sub-lattice of the zirconia may be sufficient to induce defect production, however, no evidence of defect production was observed. The displacement cross-section value of Zr was found to be {approx}400 times greater than that of O indicating that the O atoms are effectively screened from the electrons by the Zr atoms, and, therefore, the displacement of O is inefficient.

  8. An approach to an accurate determination of the energy spectrum of high-energy electron beams using magnetic spectrometry

    NASA Astrophysics Data System (ADS)

    Renner, F.; Schwab, A.; Kapsch, R.-P.; Makowski, Ch; Jannek, D.

    2014-03-01

    At the national metrology institute of Germany, the Physikalisch-Technische Bundesanstalt, a research accelerator for dosimetry in radiation therapy has been installed. Magnetic spectrometry is used to determine the spectrum of high-energy electrons generated by this accelerator. Regarding the intended experiments at the accelerator, a high accuracy for the energy determination of the electron beam is required. For this purpose, an experimental setup is used that has a number of additional devices assembled around the spectrometer to determine geometric characteristics of the electron beam, which influence the energy analysis. For the analysis of the acquired data, a software was developed which meets specific needs. One important aspect is that the software is based on an algorithm for energy determination which considers the measured magnetic flux density of the spectrometer and geometric details of the beam and the spectrometer. The software also meets the demand that it can be used to estimate the uncertainty assigned to the energy. This paper covers the experimental and analytical background of magnetic spectrometry at the high-energy beamline of PTB's research accelerator. A comparison of results calculated with the specific algorithm for energy determination which was developed for this experimental setup and with well-known algorithms is given to show the advantage of the specific method. Results of measurements and their analysis with the algorithm are presented as well.

  9. High Energy Laboratory Astrophysics Experiments using electron beam ion traps and advanced light sources

    NASA Astrophysics Data System (ADS)

    Brown, Gregory V.; Beiersdorfer, Peter; Bernitt, Sven; Eberle, Sita; Hell, Natalie; Kilbourne, Caroline; Kelley, Rich; Leutenegger, Maurice; Porter, F. Scott; Rudolph, Jan; Steinbrugge, Rene; Traebert, Elmar; Crespo-Lopez-Urritia, Jose R.

    2015-08-01

    We have used the Lawrence Livermore National Laboratory's EBIT-I electron beam ion trap coupled with a NASA/GSFC microcalorimeter spectrometer instrument to systematically address problems found in the analysis of high resolution X-ray spectra from celestial sources, and to benchmark atomic physics codes employed by high resolution spectral modeling packages. Our results include laboratory measurements of transition energies, absolute and relative electron impact excitation cross sections, charge exchange cross sections, and dielectronic recombination resonance strengths. More recently, we have coupled to the Max-Plank Institute for Nuclear Physics-Heidelberg's FLASH-EBIT electron beam ion trap to third and fourth generation advanced light sources to measure photoexcitation and photoionization cross sections, as well as, natural line widths of X-ray transitions in highly charged iron ions. Selected results will be presented.

  10. Self-Amplified Spontaneous Emission Free-Electron Laser with an Energy-Chirped Electron Beam and Undulator Tapering

    SciTech Connect

    Giannessi, L.; Ciocci, F.; Dattoli, G.; Del Franco, M.; Petralia, A.; Quattromini, M.; Ronsivalle, C.; Sabia, E.; Spassovsky, I.; Surrenti, V.; Bacci, A.; Rossi, A. R.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Cultrera, L.; Filippetto, D.; Di Pirro, G.; Ferrario, M.; Ficcadenti, L.

    2011-04-08

    We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

  11. Self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering.

    PubMed

    Giannessi, L; Bacci, A; Bellaveglia, M; Briquez, F; Castellano, M; Chiadroni, E; Cianchi, A; Ciocci, F; Couprie, M E; Cultrera, L; Dattoli, G; Filippetto, D; Del Franco, M; Di Pirro, G; Ferrario, M; Ficcadenti, L; Frassetto, F; Gallo, A; Gatti, G; Labat, M; Marcus, G; Moreno, M; Mostacci, A; Pace, E; Petralia, A; Petrillo, V; Poletto, L; Quattromini, M; Rau, J V; Ronsivalle, C; Rosenzweig, J; Rossi, A R; Rossi Albertini, V; Sabia, E; Serluca, M; Spampinati, S; Spassovsky, I; Spataro, B; Surrenti, V; Vaccarezza, C; Vicario, C

    2011-04-08

    We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

  12. Beam Energy Scaling of Ion-Induced Electron Yield from K+ Impact on Stainless Steel

    SciTech Connect

    Covo, M K; Molvik, A; Friedman, A; Westenskow, G; Barnard, J J; Cohen, R; Seidl, P; Kwan, J W; Logan, G; Baca, D; Bieniosek, F; Celata, C M; Vay, J; Vujic, J L

    2006-03-06

    Electron clouds limit the performance of many major accelerators and storage rings. Significant quantities of electrons result when halo ions are lost to beam tubes, generating gas which can be ionized and ion-induced electrons that can multiply and accumulate, causing degradation or loss of the ion beam. In order to understand the physical mechanisms of ion-induced electron production, experiments studied the impact of 50 to 400 keV K{sup +} ions on stainless steel surfaces near grazing incidence, using the 500 kV Ion Source Test Stand (STS-500) at LLNL. The experimental electron yield scales with the electronic component (dE{sub e}/dx) of the stopping power and its angular dependence does not follow l/cos({theta}). A theoretical model is developed, using TRIM code to evaluate dE{sub e}/dx at several depths in the target, to estimate the electron yield, which is compared with the experimental results. The experiment extends the range of energy from previous works and the model reproduces the angular dependence and magnitude of the electron yield.

  13. Determination of the Displacement Energies of O, Si and Zr Under Electron Beam Irradiation

    SciTech Connect

    Edmondson, P. D.; Weber, William J.; Namavar, Fereydoon; Zhang, Yanwen

    2012-03-01

    The response of nanocrystalline, stabilizer-free cubic zirconia thin films on a Si substrate to electron beam irradiation with energies of 4, 110 and 200 keV and fluences up to ~1.5 x 10²²e m² has been studied to determine the displacement energies. The 110 and 200 keV irradiations were performed in situ using a transmission electron microscope; the 4 keV irradiations were performed ex situ using an electron gun. In all three irradiations, no structural modification of the zirconia was observed, despite the high fluxes and fluences. However the Si substrate on which the zirconia film was deposited was amorphized under the 200 keV electron irradiation. Examination of the electron–solid interactions reveals that the kinetic energy transfer from the 200 keV electrons to the silicon lattice is sufficient to cause atomic displacements, resulting in amorphization. The kinetic energy transfer from the 200 keV electrons to the oxygen sub-lattice of the zirconia may be sufficient to induce defect production, however, no evidence of defect production was observed. The displacement cross-section value of Zr was found to be ~400 times greater than that of O indicating that the O atoms are effectively screened from the electrons by the Zr atoms, and, therefore, the displacement of O is inefficient.

  14. Compact electron beam focusing column

    SciTech Connect

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

    2001-07-13

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

  15. Absolute dose determination in high-energy electron beams: Comparison of IAEA dosimetry protocols

    PubMed Central

    Sathiyan, S.; Ravikumar, M.

    2008-01-01

    In this study, absorbed doses were measured and compared for high-energy electrons (6, 9, 12, 16, and 20 MeV) using International Atomic Energy Agency (IAEA), Technical Reports Series No. 277 (TRS), TRS 381, and TRS 398 dosimetry protocols. Absolute dose measurements were carried out using FC65-G Farmer chamber and Nordic Association of Clinical Physicists (NACP) parallel plate chamber with DOSE1 electrometer in WP1-D water phantom for reference field size of 15 × 15 cm2 at 100 cm source-to-surface distance. The results show that the difference between TRS 398 and TRS 381 was about 0.24% to 1.3% depending upon the energy, and the maximum difference between TRS 398 and TRS 277 was 1.5%. The use of cylindrical chamber in electron beam gives the maximum dose difference between the TRS 398 and TRS 277 in the order of 1.4% for energies above 10 MeV (R50 > 4 g/cm2). It was observed that the accuracy of dose estimation was better with the protocols based on the water calibration procedures, as no conversion quantities are involved for conversion of dose from air to water. The cross-calibration procedure of parallel plate chamber with high-energy electron beams is recommended as it avoids pwall correction factor entering into the determination of kQ,Qo. PMID:19893700

  16. Energy loss of proton, alpha particle, and electron beams in hafnium dioxide films

    SciTech Connect

    Behar, Moni; Fadanelli, Raul C.; Nagamine, Luiz C. C. M.; Abril, Isabel; Denton, Cristian D.; Garcia-Molina, Rafael; Arista, Nestor R.

    2009-12-15

    The electronic stopping power, S, of HfO{sub 2} films for proton and alpha particle beams has been measured and calculated. The experimental data have been obtained by the Rutherford backscattering technique and cover the range of 120-900 and 120-3000 keV for proton and alpha particle beams, respectively. Theoretical calculations of the energy loss for the same projectiles have been done by means of the dielectric formalism using the Mermin energy loss function--generalized oscillator strength (MELF-GOS) model for a proper description of the HfO{sub 2} target on the whole momentum-energy excitation spectrum. At low projectile energies, a nonlinear theory based on the extended Friedel sum rule has been employed. The calculations and experimental measurements show good agreement for protons and a quite good one for alpha particles. In particular, the experimental maximums of both stopping curves (around 120 and 800 keV, respectively) are well reproduced. On the basis of this good agreement, we have also calculated the inelastic mean-free path (IMFP) and the stopping power for electrons in HfO{sub 2} films. Our results predict a minimum value of the IMFP and a maximum value of the S for electrons with energies around 120 and 190 eV, respectively.

  17. Energy correction for the BGO calorimeter of DAMPE using an electron beam

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Ying; Zhang, Zhi-Yong; Wei, Yi-Feng; Wang, Chi; Zhang, Yun-Long; Wen, Si-Cheng; Wang, Xiao-Lian; Xu, Zi-Zong; Huang, Guang-Shun

    2016-08-01

    The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons, electrons and positrons originating from deep space. The electromagnetic calorimeter (ECAL), made of bismuth germinate (BGO), is one of the key sub-detectors of DAMPE, and is designed for energy measurement with a large dynamic range from 5 GeV to 10 TeV. In this paper, methods for energy correction are discussed, in order to reconstruct the primary energy of the incident electrons. Different methods are chosen for the appropriate energy ranges. The correction results of Geant4 simulation and beam test data (at CERN) are presented. Supported by the Chinese 973 Program (2010CB833002), the Strategic Priority Research Program on Space Science of the Chinese Academy of Science (XDA04040202-4) and 100 Talents Program of CAS

  18. Technical Note: On the impact of the incident electron beam energy on the primary dose component of flattening filter free photon beams.

    PubMed

    Kuess, Peter; Georg, Dietmar; Palmans, Hugo; Lechner, Wolfgang

    2016-08-01

    For commercially available linear accelerators (Linacs), the electron energies of flattening filter free (FFF) and flattened (FF) beams are either identical or the electron energy of the FFF beam is increased to match the percentage depth dose curve (PDD) of the FF beam (in reference geometry). This study focuses on the primary dose components of FFF beams for both kinds of settings, studied on the same Linac. The measurements were conducted on a VersaHD Linac (Elekta, Crawley, UK) for both FF and FFF beams with nominal energies of 6 and 10 MV. In the clinical setting of the VersaHD, the energy of FFFM (Matched) beams is set to match the PDDs of the FF beams. In contrast the incident electron beam of the FFFU beam was set to the same energy as for the FF beam. Half value layers (HVLs) and a dual parameter beam quality specifier (DPBQS) were determined. For the 6 MV FFFM beam, HVL and DPBQS values were very similar compared to those of the 6 MV FF beam, while for the 10 MV FFFM and FF beams, only %dd(10)x and HVL values were comparable (differences below 1.5%). This shows that matching the PDD at one depth does not guarantee other beam quality dependent parameters to be matched. For FFFU beams, all investigated beam quality specifiers were significantly different compared to those for FF beams of the same nominal accelerator potential. The DPBQS of the 6 MV FF and FFFM beams was equal within the measurement uncertainty and was comparable to published data of a machine with similar TPR20,10 and %dd(10)x. In contrast to that, the DPBQS's two parameters of the 10 MV FFFM beam were substantially higher compared to those for the 10 MV FF beam. PDD-matched FF and FFF beams of both nominal accelerator potentials were observed to have similar HVL values, indicating similarity of their primary dose components. Using the DPBQS revealed that the mean attenuation coefficient was found to be the same within the uncertainty of 0.8% for 6 MV FF and 6 MV FFFM beams, while for 10 MV

  19. Spectrum bandwidth narrowing of Thomson scattering X-rays with energy chirped electron beams from laser wakefield acceleration

    SciTech Connect

    Xu, Tong; Chen, Min Li, Fei-Yu; Yu, Lu-Le; Sheng, Zheng-Ming; Zhang, Jie

    2014-01-06

    We study incoherent Thomson scattering between an ultrashort laser pulse and an electron beam accelerated from a laser wakefield. The energy chirp effects of the accelerated electron beam on the final radiation spectrum bandwidth are investigated. It is found that the scattered X-ray radiation has the minimum spectrum width and highest intensity as electrons are accelerated up to around the dephasing point. Furthermore, it is proposed that the electron acceleration process inside the wakefield can be studied by use of 90° Thomson scattering. The dephasing position and beam energy chirp can be deduced from the intensity and bandwidth of the scattered radiation.

  20. Suppression of Divergence of Low Energy Ion Beams by Space Charge Neutralization with Low Energy Electrons Emitted from Field Emitter Arrays

    SciTech Connect

    Ishikawa, Junzo; Gotoh, Yasuhito; Taguchi, Shuhei; Nicolaescu, Dan; Tsuji, Hiroshi; Kimoto, Tsunenobu; Takeuchi, Mitsuaki; Sakai, Shigeki

    2011-01-07

    Suppression of divergence of low energy neon ion beam was experimentally demonstrated by neutralizing the space charge of ion beam with low energy electrons emitted from silicon field emitter arrays (Si-FEAs). Treatment of the FEAs with trifluoromethane plasma realized surface carbonization which was efficient to elongate the lifetime of the FEA and to improve the electron energy distribution. Together with the improvement of the performance of Si-FEA, we have developed a novel electron deceleration system to produce low energy electrons. A low energy neon ion beam was produced and the beam property was investigated with and without the electron supply from surface carbonized Si-FEA (Si:C-FEA). As a result, the divergence of the neon ion beam was largely suppressed with presence of the electrons.

  1. Amplification of a fast wave by extracting both the kinetic energy and electrostatic potential energy of a large-orbit relativistic electron beam in a coaxial electrostatic wiggler

    SciTech Connect

    Zhang Shichang

    2010-05-15

    Nonlinear model and simulation technique of the interaction and energy transfer between a fast wave and a large-orbit relativistic electron beam in a coaxial electrostatic wiggler are presented. Unlike the situations in a magnetostatic-wiggler free-electron laser (MWFEL) and in an electron cyclotron maser (ECM), the electrostatic potential of the electrons plays an important role and participates in the energy exchange between the wave and the electron beam. Compared to MWFEL and ECM, the coaxial electrostatic-wiggler configuration has a distinguishing peculiarity that besides the electron-beam's kinetic energy, its electrostatic potential energy can be effectively transferred to the fast wave. Simulation shows that wave could be amplified with ultrahigh gain by extracting both the kinetic energy and electrostatic potential energy of the electron beam.

  2. Sensitivity of echo enabled harmonic generation to sinusoidal electron beam energy structure

    NASA Astrophysics Data System (ADS)

    Hemsing, E.; Garcia, B.; Huang, Z.; Raubenheimer, T.; Xiang, D.

    2017-06-01

    We analytically examine the bunching factor spectrum of a relativistic electron beam with sinusoidal energy structure that then undergoes an echo-enabled harmonic generation (EEHG) transformation to produce high harmonics. The performance is found to be described primarily by a simple scaling parameter. The dependence of the bunching amplitude on fluctuations of critical parameters is derived analytically, and compared with simulations. Where applicable, EEHG is also compared with high gain harmonic generation (HGHG) and we find that EEHG is generally less sensitive to several types of energy structure. In the presence of intermediate frequency modulations like those produced by the microbunching instability, EEHG has a substantially narrower intrinsic bunching pedestal.

  3. Inverse Compton Scattering as a Diagnostic Tool for the Measurement of Electron Beam Energies in Diodes

    NASA Astrophysics Data System (ADS)

    Critchley, A. D. J.

    2003-10-01

    The main emphasis of the diode research project at the Atomic Weapons Establishment (AWE) UK is to produce small diameter radiographic spot sizes at high dose to improve the resolution of the transmission radiographs taken during hydrodynamic experiments. Experimental measurements of conditions within the diodes of Pulsed Power driven flash x-ray machines are vital to provide a benchmark for electromagnetic PIC codes such as LSP which are used to develop new diode designs. The potential use of inverse Compton scattering (ICS) as a diagnostic technique in the determination of electron energies within the diode has been investigated. The interaction of a laser beam with a beam of high-energy electrons will create an ICS spectrum of photons. Theoretically, one should be able to glean information on the energies and positions of the electrons from the energy spectrum and differential cross section of the scattered photons. The feasibility of fielding this technique on various diode designs has been explored, and an experimental setup with the greatest likelihood of success is proposed.

  4. The clinical potential of high energy, intensity and energy modulated electron beams optimized by simulated annealing for conformal radiation therapy

    NASA Astrophysics Data System (ADS)

    Salter, Bill Jean, Jr.

    Purpose. The advent of new, so called IVth Generation, external beam radiation therapy treatment machines (e.g. Scanditronix' MM50 Racetrack Microtron) has raised the question of how the capabilities of these new machines might be exploited to produce extremely conformal dose distributions. Such machines possess the ability to produce electron energies as high as 50 MeV and, due to their scanned beam delivery of electron treatments, to modulate intensity and even energy, within a broad field. Materials and methods. Two patients with 'challenging' tumor geometries were selected from the patient archives of the Cancer Therapy and Research Center (CTRC), in San Antonio Texas. The treatment scheme that was tested allowed for twelve, energy and intensity modulated beams, equi-spaced about the patient-only intensity was modulated for the photon treatment. The elementary beams, incident from any of the twelve allowed directions, were assumed parallel, and the elementary electron beams were modeled by elementary beam data. The optimal arrangement of elementary beam energies and/or intensities was optimized by Szu-Hartley Fast Simulated Annealing Optimization. Optimized treatment plans were determined for each patient using both the high energy, intensity and energy modulated electron (HIEME) modality, and the 6 MV photon modality. The 'quality' of rival plans were scored using three different, popular objective functions which included Root Mean Square (RMS), Maximize Dose Subject to Dose and Volume Limitations (MDVL - Morrill et. al.), and Probability of Uncomplicated Tumor Control (PUTC) methods. The scores of the two optimized treatments (i.e. HIEME and intensity modulated photons) were compared to the score of the conventional plan with which the patient was actually treated. Results. The first patient evaluated presented a deeply located target volume, partially surrounding the spinal cord. A healthy right kidney was immediately adjacent to the tumor volume, separated

  5. Electron-beam charging of dielectrics preirradiated with moderate-energy ions and electrons

    NASA Astrophysics Data System (ADS)

    Rau, E. I.; Tatarintsev, A. A.; Zykova, E. Yu.; Ivanenko, I. P.; Kupreenko, S. Yu.; Minnebaev, K. F.; Khaidarov, A. A.

    2017-08-01

    The effects of charging of dielectric targets irradiated with moderate-energy electrons in a scanning electron microscope are examined. Considerable differences in the kinetics of charging of the reference samples and the samples preirradiated with ions and electrons are reported. These differences are attributed to the processes of radiation-induced defect formation in Al2O3 (sapphire) and SiO2 that are, however, dissimilar in nature. The contributions of surface structure modification and changes in the electrophysical parameters of the surface (specifically, the charge spreading effect) are revealed. Critical doses of irradiation with Ar+ ions and electrons inducing active defect formation in dielectric targets and critical values of internal charge fields producing a significant contribution to the temporal parameters of Al2O3 and SiO2 charging are determined.

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

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  7. Electron Beam Freeform Fabrication

    NASA Image and Video Library

    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...

  8. Optical transition radiation used in the diagnostic of low energy and low current electron beams in particle accelerators

    NASA Astrophysics Data System (ADS)

    Silva, T. F.; Bonini, A. L.; Lima, R. R.; Maidana, N. L.; Malafronte, A. A.; Pascholati, P. R.; Vanin, V. R.; Martins, M. N.

    2012-09-01

    Optical transition radiation (OTR) plays an important role in beam diagnostics for high energy particle accelerators. Its linear intensity with beam current is a great advantage as compared to fluorescent screens, which are subject to saturation. Moreover, the measurement of the angular distribution of the emitted radiation enables the determination of many beam parameters in a single observation point. However, few works deals with the application of OTR to monitor low energy beams. In this work we describe the design of an OTR based beam monitor used to measure the transverse beam charge distribution of the 1.9-MeV electron beam of the linac injector of the IFUSP microtron using a standard vision machine camera. The average beam current in pulsed operation mode is of the order of tens of nano-Amps. Low energy and low beam current make OTR observation difficult. To improve sensitivity, the beam incidence angle on the target was chosen to maximize the photon flux in the camera field-of-view. Measurements that assess OTR observation (linearity with beam current, polarization, and spectrum shape) are presented, as well as a typical 1.9-MeV electron beam charge distribution obtained from OTR. Some aspects of emittance measurement using this device are also discussed.

  9. Optical transition radiation used in the diagnostic of low energy and low current electron beams in particle accelerators.

    PubMed

    Silva, T F; Bonini, A L; Lima, R R; Maidana, N L; Malafronte, A A; Pascholati, P R; Vanin, V R; Martins, M N

    2012-09-01

    Optical transition radiation (OTR) plays an important role in beam diagnostics for high energy particle accelerators. Its linear intensity with beam current is a great advantage as compared to fluorescent screens, which are subject to saturation. Moreover, the measurement of the angular distribution of the emitted radiation enables the determination of many beam parameters in a single observation point. However, few works deals with the application of OTR to monitor low energy beams. In this work we describe the design of an OTR based beam monitor used to measure the transverse beam charge distribution of the 1.9-MeV electron beam of the linac injector of the IFUSP microtron using a standard vision machine camera. The average beam current in pulsed operation mode is of the order of tens of nano-Amps. Low energy and low beam current make OTR observation difficult. To improve sensitivity, the beam incidence angle on the target was chosen to maximize the photon flux in the camera field-of-view. Measurements that assess OTR observation (linearity with beam current, polarization, and spectrum shape) are presented, as well as a typical 1.9-MeV electron beam charge distribution obtained from OTR. Some aspects of emittance measurement using this device are also discussed.

  10. Backscatter towards the monitor ion chamber in high-energy photon and electron beams: charge integration versus Monte Carlo simulation.

    PubMed

    Verhaegen, F; Symonds-Tayler, R; Liu, H H; Nahum, A E

    2000-11-01

    In some linear accelerators, the charge collected by the monitor ion chamber is partly caused by backscattered particles from accelerator components downstream from the chamber. This influences the output of the accelerator and also has to be taken into account when output factors are derived from Monte Carlo simulations. In this work, the contribution of backscattered particles to the monitor ion chamber response of a Varian 2100C linac was determined for photon beams (6, 10 MV) and for electron beams (6, 12, 20 MeV). The experimental procedure consisted of charge integration from the target in a photon beam or from the monitor ion chamber in electron beams. The Monte Carlo code EGS4/BEAM was used to study the contribution of backscattered particles to the dose deposited in the monitor ion chamber. Both measurements and simulations showed a linear increase in backscatter fraction with decreasing field size for photon and electron beams. For 6 MV and 10 MV photon beams, a 2-3% increase in backscatter was obtained for a 0.5 x 0.5 cm2 field compared to a 40 x 40 cm2 field. The results for the 6 MV beam were slightly higher than for the 10 MV beam. For electron beams (6, 12, 20 MeV), an increase of similar magnitude was obtained from measurements and simulations for 6 MeV electrons. For higher energy electron beams a smaller increase in backscatter fraction was found. The problem is of less importance for electron beams since large variations of field size for a single electron energy usually do not occur.

  11. Emittance growth of an electron beam in a periodic focusing channel due to transfer of longitudinal energy to transverse energy

    SciTech Connect

    Carlsten, B.E.

    1998-12-31

    Most discussions about emittance growth and halo production for an intense electron beam in a periodic focusing channel assume that the total transverse energy is constant (or, in other words, that the transverse and longitudinal Hamiltonians are separable). Previous analyses that include variations in the total transverse energy are typically based on a transverse-longitudinal coupling that is either from two-dimensional space-charge modes or particle-particle Coulomb collisions. With the space-charge modes, the energy exchange between the transverse and longitudinal directions is periodic, and of constant magnitude. The total energy transfer for the case of the Coulomb collisions is negligible. This limited increase of energy in the transverse direction from these other effects will limit the amount of transverse emittance growth possible. In this paper, the authors investigate a mechanism in which there is a continual transfer of energy from the longitudinal direction to the transverse direction, leading to essentially unlimited potential transverse emittance growth. This mechanism is caused by an asymmetry of the beam`s betatron motion within the periodic focusing elements. This analysis is based on thermodynamic principles. This mechanism exists for both solenoids and quadrupole focusing, although only solenoid focusing is studied here.

  12. High energy micro electron beam generation using chirped laser pulse in the presence of an axial magnetic field

    SciTech Connect

    Akou, H. Hamedi, M.

    2015-10-15

    In this paper, the generation of high-quality and high-energy micro electron beam in vacuum by a chirped Gaussian laser pulse in the presence of an axial magnetic field is numerically investigated. The features of energy and angular spectra, emittances, and position distribution of electron beam are compared in two cases, i.e., in the presence and absence of an external magnetic field. The electron beam is accelerated with higher energy and qualified in spatial distribution in the presence of the magnetic field. The presence of an axial magnetic field improves electron beam spatial quality as well as its gained energy through keeping the electron motion parallel to the direction of propagation for longer distances. It has been found that a 64 μm electron bunch with about MeV initial energy becomes a 20 μm electron beam with high energy of the order of GeV, after interacting with a laser pulse in the presence of an external magnetic field.

  13. Model of convection mass transfer in titanium alloy at low energy high current electron beam action

    NASA Astrophysics Data System (ADS)

    Sarychev, V. D.; Granovskii, A. Yu; Nevskii, S. A.; Konovalov, S. V.; Gromov, V. E.

    2017-01-01

    The convection mixing model is proposed for low-energy high-current electron beam treatment of titanium alloys, pre-processed by heterogeneous plasma flows generated via explosion of carbon tape and powder TiB2. The model is based on the assumption vortices in the molten layer are formed due to the treatment by concentrated energy flows. These vortices evolve as the result of thermocapillary convection, arising because of the temperature gradient. The calculation of temperature gradient and penetration depth required solution of the heat problem with taking into account the surface evaporation. However, instead of the direct heat source the boundary conditions in phase transitions were changed in the thermal conductivity equation, assuming the evaporated material takes part in the heat exchange. The data on the penetration depth and temperature distribution are used for the thermocapillary model. The thermocapillary model embraces Navier-Stocks and convection heat transfer equations, as well as the boundary conditions with the outflow of evaporated material included. The solution of these equations by finite elements methods pointed at formation of a multi-vortices structure when electron-beam treatment and its expansion over new zones of material. As the result, strengthening particles are found at the depth exceeding manifold their penetration depth in terms of the diffusion mechanism.

  14. Design and operation of a retarding field energy analyzer with variable focusing for space-charge-dominated electron beams

    NASA Astrophysics Data System (ADS)

    Cui, Y.; Zou, Y.; Valfells, A.; Reiser, M.; Walter, M.; Haber, I.; Kishek, R. A.; Bernal, S.; O'Shea, P. G.

    2004-08-01

    A retarding electrostatic field energy analyzer for low-energy beams has been designed, simulated, and tested with electron beams of several keV, in which space-charge effects play an important role. A cylindrical focusing electrode is used to overcome the beam expansion inside the device due to space-charge forces, beam emittance, etc. The cylindrical focusing voltage is independently adjustable to provide proper focusing strength. Single particle simulation and theoretical error analysis using beam envelopes show that this energy analyzer can get very high resolution for low-energy beams (up to 10 keV), which was found to be in good agreement with experimental results. The measured beam energy spectrum is both temporally and spatially resolved. In addition, a computer-controlled automatic system is developed and significantly improves the speed and efficiency of the data acquisition and processing. The measured beam energy spreads, are in remarkably good agreement with the intrinsic limits set by the effects of nonadiabatic acceleration in the electron gun and that of Coulomb collisions, as predicted by theory.

  15. Joining Carbon-Carbon Composites and High-Temperature Materials with High Energy Electron Beams

    NASA Technical Reports Server (NTRS)

    Goodman, Daniel; Singler, Robert

    1998-01-01

    1. Program goals addressed during this period. Experimental work was directed at formation of a low-stress bond between carbon- carbon and aluminum, with the objective of minimizing the heating of the aluminum substrate, thereby minimizing stresses resulting from the coefficient of thermal expansion (CTE) difference between the aluminum and carbon-carbon. A second objective was to form a bond between carbon-carbon and aluminum with good thermal conductivity for electronic thermal management (SEM-E) application. 2. Substrates and joining materials selected during this period. Carbon-Carbon Composite (CCC) to Aluminum. CCC (Cu coated) to Aluminum. Soldering compounds based on Sn/Pb and Sn/Ag/Cu/Bi compositions. 3. Soldering experiments performed. Conventional techniques. High Energy Electron Beam (HEEB) process.

  16. 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.

  17. Generation of high brightness electron beam by brake-applied velocity bunching with a relatively low energy chirp

    NASA Astrophysics Data System (ADS)

    Huang, Ruixuan; He, Zhigang; Li, Biaobin; Zhang, Shancai; Li, Weiwei; Jia, Qika; Wang, Lin

    2017-09-01

    Velocity bunching technique is a tool for compressing electron beams in modern high brightness photoinjector sources, which utilizes the velocity difference introduced by a traveling rf wave at a relatively low energy. It presents peculiar challenges when applied to obtain a beam with a very high current and a low transverse emittance in photoinjectors. The main difficulty is to control the emittance oscillations of the beam during high compression, which can be naturally considered as an extension of the emittance compensation process. In this paper, a brake-applied velocity bunching scheme is proposed, in which the electron bunch is injected into the accelerator with a low gradient at a deceleration phase, like ;a brake is applied;, afterward slips to an acceleration phase. During the entire compression process, the energy chirp induced by the rf field is mostly linear, which retains a symmetric electron beam in the temporal distribution. The key point of the new scheme is a smaller energy chirp at a lower beam energy compared with the normal velocity bunching. Besides, the beam energy chirp before compression is dominated by the linear correlation due to a relatively short laser pulse. With a symmetric bunch compression, the transverse emittance could be compensated even if the compression factor is extremely high. As to our simulation results, the peak current of the compressed beam can be above 1.8 kA for the charge of 800 pC with a good emittance compensation.

  18. [Determination of absorbed dose to water for high energy photon and electron beams--comparison of different dosimetry protocols].

    PubMed

    Zakaria, Golam Abu; Schütte, Wilhelm

    2003-01-01

    The determination of absorbed dose to water for high-energy photon and electron beams is performed in Germany according to the dosimetry protocol DIN 6800-2 (1997). At an international level, the main protocols used are the AAPM dosimetry protocol TG-51 (1999) and the IAEA Code of Practice TRS-398 (2000). The present paper systematically compares these three dosimetry protocols, and identifies similarities and differences. The investigations were performed using 4 and 10 MV photon beams, as well as 6, 8, 9, 10, 12 and 14 MeV electron beams. Two cylindrical and two plane-parallel type chambers were used for measurements. In general, the discrepancies among the three protocols were 1.0% for photon beams and 1.6% for electron beams. Comparative measurements in the context of measurement technical control (MTK) with TLD showed a deviation of less than 1.3% between the measurements obtained according to protocols DIN 6800-2 and MTK (exceptions: 4 MV photons with 2.9% and 6 MeV electrons with 2.4%). While only cylindrical chambers were used for photon beams, measurements of electron beams were performed using both cylindrical and plane-parallel chambers (the latter used after a cross-calibration to a cylindrical chamber, as required by the respective dosimetry protocols). Notably, unlike recommended in the corresponding protocols, we found out that cylindrical chambers can be used also for energies from 6 to 10 MeV.

  19. SU-E-T-781: Using An Electronic Portal Imaging Device (EPID) for Correlating Linac Photon Beam Energies

    SciTech Connect

    Yaddanapudi, S; Cai, B; Sun, B; Noel, C; Goddu, S; Mutic, S

    2015-06-15

    Purpose: Electronic portal imaging devices (EPIDs) have proven to be useful for measuring several parameters of interest in linear accelerator (linac) quality assurance (QA). The purpose of this project was to evaluate the feasibility of using EPIDs for determining linac photon beam energies. Methods: Two non-clinical Varian TrueBeam linacs (Varian Medical Systems, Palo Alto, CA) with 6MV and 10MV photon beams were used to perform the measurements. The linacs were equipped with an amorphous silicon based EPIDs (aSi1000) that were used for the measurements. We compared the use of flatness versus percent depth dose (PDD) for predicting changes in linac photon beam energy. PDD was measured in 1D water tank (Sun Nuclear Corporation, Melbourne FL) and the profiles were measured using 2D ion-chamber array (IC-Profiler, Sun Nuclear) and the EPID. Energy changes were accomplished by varying the bending magnet current (BMC). The evaluated energies conformed with the AAPM TG142 tolerance of ±1% change in PDD. Results: BMC changes correlating with a ±1% change in PDD corresponded with a change in flatness of ∼1% to 2% from baseline values on the EPID. IC Profiler flatness values had the same correlation. We observed a similar trend for the 10MV beam energy changes. Our measurements indicated a strong correlation between changes in linac photon beam energy and changes in flatness. For all machines and energies, beam energy changes produced change in the uniformity (AAPM TG-142), varying from ∼1% to 2.5%. Conclusions: EPID image analysis of beam profiles can be used to determine linac photon beam energy changes. Flatness-based metrics or uniformity as defined by AAPM TG-142 were found to be more sensitive to linac photon beam energy changes than PDD. Research funding provided by Varian Medical Systems. Dr. Sasa Mutic receives compensation for providing patient safety training services from Varian Medical Systems, the sponsor of this study.

  20. Electron beam energy stabilization using a neural network hybrid controller at the Australian Synchrotron Linac.

    SciTech Connect

    Meier, E.; Morgan, M. J.; Biedron, S. G.; LeBlanc, G.; Wu, J.

    2009-01-01

    This paper describes the implementation of a neural network hybrid controller for energy stabilization at the Australian Synchrotron Linac. The structure of the controller consists of a neural network (NNET) feed forward control, augmented by a conventional Proportional-Integral (PI) feedback controller to ensure stability of the system. The system is provided with past states of the machine in order to predict its future state, and therefore apply appropriate feed forward control. The NNET is able to cancel multiple frequency jitter in real-time. When it is not performing optimally due to jitter changes, the system can successfully be augmented by the PI controller to attenuate the remaining perturbations. With a view to control the energy and bunch length at the FERMI{at}Elettra Free Electron Laser (FEL), the present study considers a neural network hybrid feed forward-feedback type of control to rectify limitations related to feedback systems, such as poor response for high jitter frequencies or limited bandwidth, while ensuring robustness of control. The Australian Synchrotron Linac is equipped with a beam position monitor (BPM), that was provided by Sincrotrone Trieste from a former transport line thus allowing energy measurements and energy control experiments. The present study will consequently focus on correcting energy jitter induced by variations in klystron phase and voltage.

  1. Characterization of the phantom material virtual water in high-energy photon and electron beams.

    PubMed

    McEwen, M R; Niven, D

    2006-04-01

    The material Virtual Water has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence-the water/Virtual Water dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement (<0.2%) between water and Virtual Water at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Water. However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurements have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values.

  2. (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.

  3. Analytic expressions for the inelastic scattering and energy loss of electron and proton beams in carbon nanotubes

    SciTech Connect

    Emfietzoglou, D.; Kyriakou, I.; Garcia-Molina, R.; Abril, I.; Kostarelos, K.

    2010-09-15

    We have determined ''effective'' Bethe coefficients and the mean excitation energy of stopping theory (I-value) for multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotube (SWCNT) bundles based on a sum-rule constrained optical-data model energy loss function with improved asymptotic properties. Noticeable differences between MWCNTs, SWCNT bundles, and the three allotropes of carbon (diamond, graphite, glassy carbon) are found. By means of Bethe's asymptotic approximation, the inelastic scattering cross section, the electronic stopping power, and the average energy transfer to target electrons in a single inelastic collision, are calculated analytically for a broad range of electron and proton beam energies using realistic excitation parameters.

  4. Electron Beam Could Probe Recombination Centers

    NASA Technical Reports Server (NTRS)

    Vonroos, O.

    1983-01-01

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

  5. Laser wakefield acceleration of polarized electron beams

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  6. Research of transportation efficiency of low-energy high- current electron beam in plasma channel in external magnetic field

    NASA Astrophysics Data System (ADS)

    Vagin, E. S.; Grigoriev, V. P.

    2015-11-01

    Effective high current (5-20 kA) and low energy (tens of keV) electrons beam transportation is possible only with almost complete charging neutralization. It is also necessary to use quite high current neutralization for elimination beam self-pinching effect. The research is based on the self-consistent mathematical model that takes into account beam and plasma particles dynamic, current and charge neutralization of electron beam and examines the transportation of electron beam into a chamber with low-pressure plasma in magnetic field. A numerical study was conducted using particle in cell (PIC) method. The study was performed with various system parameters: rise time and magnitude of the beam current, gas pressure and plasma density and geometry of the system. Regularities of local virtual cathode field generated by the beam in the plasma channel, as well as ranges of parameters that let transportation beam with minimal losses, depending on the external magnetic field were determined through a series of numerical studies. In addition, the assessment of the impact of the plasma ion mobility during the transition period and during steady beam was performed.

  7. Experimental determination of the effective point of measurement of cylindrical ionization chambers for high-energy photon and electron beams.

    PubMed

    Huang, Yanxiao; Willomitzer, Christian; Zakaria, Golam Abu; Hartmann, Guenther H

    2010-01-01

    Measurements of depth-dose curves in water phantom using a cylindrical ionization chamber require that its effective point of measurement is located at the measuring depth. Recommendations for the position of the effective point of measurement with respect to the central axis valid for high-energy electron and photon beams are given in dosimetry protocols. According to these protocols, the use of a constant shift P(eff) is currently recommended. However, this is still based on a very limited set of experimental results. It is therefore expected that an improved knowledge of the exact position of the effective point of measurement will further improve the accuracy of dosimetry. Recent publications have revealed that the position of the effective point of measurement is indeed varying with beam energy, field size and also with chamber geometry. The aim of this study is to investigate whether the shift of P(eff) can be taken to be constant and independent from the beam energy. An experimental determination of the effective point of measurement is presented based on a comparison between cylindrical chambers and a plane-parallel chamber using conventional dosimetry equipment. For electron beams, the determination is based on the comparison of halfvalue depth R(50) between the cylindrical chamber of interest and a well guarded plane-parallel Roos chamber. For photon beams, the depth of dose maximum, d(max), the depth of 80% dose, d(80), and the dose parameter PDD(10) were used. It was again found that the effective point of measurement for both, electron and photon beams Dosimetry, depends on the beam energy. The deviation from a constant value remains very small for photons, whereas significant deviations were found for electrons. It is therefore concluded that use of a single upstream shift value from the centre of the cylindrical chamber as recommended in current dosimetry protocols is adequate for photons, however inadequate for accurate electron beam dosimetry.

  8. High-Precision Calibration of Electron Beam Energy from the Hefei Light Source Using Spin Resonant Depolarization

    NASA Astrophysics Data System (ADS)

    Lan, Jie-Qin; Xu, Hong-Liang

    2014-12-01

    The electron beam energy at the Hefei Light Source (HLS) in the National Synchrotron Radiation Laboratory is highly precisely calibrated by using the method of spin resonant depolarization for the first time. The spin tune and the beam energy are determined by sweeping the frequency of a radial rf stripline oscillating magnetic field to artificially excite a spin resonance and depolarize the beam. The resonance signal is recognized by observing the sudden change of the Touschek loss counting rate of the beam. The possible systematic errors of the experiment are presented and the accuracy of the calibrated energy is shown to be about 10-4. A series of measurements show that the energy stability of the machine is of the order of 9 × 10-3.

  9. High energy Coulomb-scattered electrons for relativistic particle beams and diagnostics

    DOE PAGES

    Thieberger, P.; Altinbas, Z.; Carlson, C.; ...

    2016-03-29

    A new system used for monitoring energetic Coulomb-scattered electrons as the main diagnostic for accurately aligning the electron and ion beams in the new Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail. The theory of electron scattering from relativistic ions is developed and applied to the design and implementation of the system used to achieve and maintain the alignment. Commissioning with gold and 3He beams is then described as well as the successful utilization of the new system during the 2015 RHIC polarized proton run. Systematic errors of the new method are then estimated. Lastly, some possiblemore » future applications of Coulomb-scattered electrons for beam diagnostics are briefly discussed.« less

  10. Generation of Quasi-monoenergetic High-energy Electron Beam by Plasma Wave

    SciTech Connect

    Koyama, K.; Saito, N.; Ogata, A.; Masuda, S.; Tanimoto, M.; Miura, E.; Kato, S.; Adachi, M

    2004-12-07

    We have demonstrated an acceleration of a quasi-monoenergetic electron beam by trapping electrons in a plasma wave. Experiments were performed by focusing 2-TW (50 fs) laser pulses on supersonic gas jet targets. An intensity was 5 x 1018W/cm2(a0 = 1.5). An electron density was estimated to be 1.3 x 1020cm-3. The quasi-monoenergetic electron beam at 7 MeV was observed with a peak to foot ratio of 10. An appearance of a Stokes Raman satellite in the forward scattering well correlated with the quasi-monoenergetic electron beam. A frequency shift of the satellite coincided with a plasma frequency at the measured plasma density. Appearance of the Raman satellite coincided with appearances of a fishbone structure in a side-scattering image. Supposing the fishbone structure originated from the plasma wave, an acceleration length was estimated to be 200 to 500 microns.

  11. Electron dynamics and energy conversion in O-type linear-beam devices.

    NASA Technical Reports Server (NTRS)

    Detweiler, H. K.; Rowe, J. E.

    1971-01-01

    A general nonlinear interaction theory is used to investigate the effects of transverse fields (i.e., radial circuit fields and radial space-charge fields) in traveling-wave amplifiers for a variety of beam-focusing conditions. Magnetic focusing fields which are periodic or tapered (increased) with distance along the device are considered in addition to uniform magnetic fields. Results are presented for Brillouin flow and near-Brillouin flow, and the minimum magnetic field strength required to effectively constrain the electron beam is determined as a function of the operating parameters for the various focusing systems. Confined flow is also examined for the uniform-field case in order to have a basis of comparison from which the effects of radial motion of the beam electrons can be determined. The results indicate the importance of transverse effects and further yield information on the stability of strongly modulated cylindrical electron beams.-

  12. Graded-gap AlxGa1-xAs detector for high-energy electron beam dosimetry

    NASA Astrophysics Data System (ADS)

    Silenas, Aldis; Miller, Albert; Pozela, Juras; Pozela, Karolis; Dapkus, Leonas; Juciene, Vida

    2011-05-01

    A new graded-gap p-Al0.2Ga0.8As-p-AlxGa1-xAs-n-GaAs detector structure with internal optical response was developed and investigated as a detector for high-energy electron beam dosimetry. An additional p-Al0.2Ga0.8As top layer was grown on the narrow-gap side of the structure. This thin (2 μm) top layer significantly reduces nonradiative surface recombination and increases detector sensitivity for high-energy electron beams by about 10-13%. The increase in doping level of the graded-gap AlxGa1-xAs layer from p=3×1017 to 1.9×1018 cm-3 increases detector sensitivity by about 2.3 times. The detector was encapsulated into a plastic body and fitted for dosimetric measurements in a water phantom. Linear response on absorbed dose and dose rate was obtained for beams with electron energies of 6, 12 and 20 MeV. A good agreement of relative depth dose distribution measured by the AlxGa1-xAs detector and ionization chamber is obtained for the 6 MeV energy electron beam, but a discernible discrepancy is observed for the higher electron energies.

  13. Influence of the electron energy and number of beams on the absorbed dose distributions in radiotherapy of deep seated targets.

    PubMed

    Garnica-Garza, H M

    2014-12-01

    With the advent of compact laser-based electron accelerators, there has been some renewed interest on the use of such charged particles for radiotherapy purposes. Traditionally, electrons have been used for the treatment of fairly superficial lesions located at depths of no more than 4cm inside the patient, but lately it has been proposed that by using very high energy electrons, i.e. those with an energy in the order of 200-250MeV it should be possible to safely reach deeper targets. In this paper, we used a realistic patient model coupled with detailed Monte Carlo simulations of the electron transport in such a patient model to examine the characteristics of the resultant absorbed dose distributions as a function of both the electron beam energy as well as the number of beams for a particular type of treatment, namely, a prostate radiotherapy treatment. Each treatment is modeled as consisting of nine, five or three beam ports isocentrically distributed around the patient. An optimization algorithm is then applied to obtain the beam weights in each treatment plan. It is shown that for this particularly challenging case, both excellent target coverage and critical structure sparing can be obtained for energies in the order of 150MeV and for as few as three treatment ports, while significantly reducing the total energy absorbed by the patient with respect to a conventional megavoltage x-ray treatment.

  14. Beam Energy Scaling on Ion-Induced Electron Yield from K+ Impacton Stainless Steel

    SciTech Connect

    Kireeff Covo, Michel; Molvik, Arthur; Friedman, Alex; Westenskow,Glen; Barnard, John J.; Cohen, Ronald; Grote, David; Lund, Steven M.; Seidl, Peter; Kwan, Joe W.; Logan, Grant; Baca, David; Bieniosek, Frank; Celata, Christine M.; Vay Jean-Luc; Vujic, Jasmina L.

    2006-01-01

    Electron clouds limit the performance of many major accelerators. Significant quantities of electrons result when halo ions are lost to beam tubes, generating gas which can be ionized and ion-induced electrons that can multiply and accumulate, causing degradation or loss of the ion beam. In order to understand the physical mechanisms of ion-induced electron production, experiments studied the impact of 50 to 400 keV K{sup +} ions on stainless steel surfaces near grazing incidence, using the 500 kilovolts Ion Source Test Stand (STS-500) at LLNL. The experimental electron yield scales with the electronic component (dE{sub e}/dx) of the stopping power. A theoretical model is developed, using TRIM code to evaluate dE{sub e}/dx at several depths in the target, to estimate the electron yield, which is compared with the experimental results.

  15. Dependence of the Electron Beam Energy and Types of Surface to Determine EBSD Indexing Reliability in Yttria-Stabilized Zirconia

    SciTech Connect

    Saraf, Laxmikant V.

    2012-04-01

    Electron backscatter diffraction (EBSD) is a powerful technique for the surface microstructure analysis. EBSD analysis of cubic yttria-stabilized zirconia (YSZ) in two and three dimensions (2-D, 3-D) is demonstrated using sequential slicing from a focused ion beam (FIB) followed by EBSD mapping to represent 3-D reconstructed high density grain structure with random orientation. The statistics related to accuracy of EBSD band detection shows that probability of accurate grain orientation detection increased significantly when the electron beam energy is increased from 10 kV to 30 kV. As a result of better sampling with increased interaction volume, a disparity between local and average grain orientation angle also exhibited the dependence of the electron beam energy to determine the accuracy of grain orientation. To study the accuracy and quality of EBSD band detection as a function of surface roughness and over layer formation, rapid EBSD measurement tests are performed on (a) YSZ surfaces ion-polished at ion beam energies of 65 nA at 30 kV and 1 nA at 30 kV and (b) carbon coated versus uncoated YSZ surfaces. The EBSD results at both 10 kV and 30 kV electron beam energies indicate that EBSD band detection accuracy is negatively affected by surface roughness and amorphous over layer formation.

  16. Dependence of the electron beam energy and types of surface to determine EBSD indexing reliability in yttria-stabilized zirconia.

    PubMed

    Saraf, Laxmikant V

    2012-04-01

    Electron backscatter diffraction (EBSD) is a powerful technique for surface microstructure analysis. EBSD analysis of cubic yttria-stabilized zirconia (YSZ) is demonstrated. The statistics related to EBSD indexing reliability shows that the probability of accurate grain orientation detection increased significantly when the electron beam energy was increased from 10 to 30 kV. As a result of better sampling with increased interaction volume, a disparity between local and average grain misorientation angle also exhibited the dependence of the electron beam energy to determine the accuracy of grain orientation. To study EBSD indexing reliability as a function of surface roughness and overlayer formation, rapid EBSD measurement tests were performed on (a) YSZ surfaces ion-polished at ion beam energies of 65 nA at 30 kV and 1 nA at 30 kV and (b) carbon-coated versus uncoated YSZ surfaces. The EBSD results at both 10 and 30 kV electron beam energies indicate that EBSD indexing reliability is negatively affected by higher ion beam milling current and amorphous overlayer formation.

  17. Attenuation of 10 MeV electron beam energy to achieve low doses does not affect Salmonella spp. inactivation kinetics

    NASA Astrophysics Data System (ADS)

    Hieke, Anne-Sophie Charlotte; Pillai, Suresh D.

    2015-05-01

    The effect of attenuating the energy of a 10 MeV electron beam on Salmonella inactivation kinetics was investigated. No statistically significant differences were observed between the D10 values of either Salmonella 4,[5],12:i:- or a Salmonella cocktail (S. 4,[5],12:i:-, Salmonella Heidelberg, Salmonella Newport, Salmonella Typhimurium, Salmonella) when irradiated with either a non-attenuated 10 MeV eBeam or an attenuated 10 MeV eBeam (~2.9±0.22 MeV). The results show that attenuating the energy of a 10 MeV eBeam to achieve low doses does not affect the inactivation kinetics of Salmonella spp. when compared to direct 10 MeV eBeam irradiation.

  18. Extrapolation chamber mounted on perspex for calibration of high energy photon and electron beams from a clinical linear accelerator.

    PubMed

    Ravichandran, R; Binukumar, J P; Sivakumar, S S; Krishnamurthy, K; Davis, C A

    2009-01-01

    The objective of the present study is to establish radiation standards for absorbed doses, for clinical high energy linear accelerator beams. In the nonavailability of a cobalt-60 beam for arriving at Nd, water values for thimble chambers, we investigated the efficacy of perspex mounted extrapolation chamber (EC) used earlier for low energy x-rays and beta dosimetry. Extrapolation chamber with facility for achieving variable electrode separations 10.5mm to 0.5mm using micrometer screw was used for calibrations. Photon beams 6 MV and 15 MV and electron beams 6 MeV and 15 MeV from Varian Clinac linacs were calibrated. Absorbed Dose estimates to Perspex were converted into dose to solid water for comparison with FC 65 ionisation chamber measurements in water. Measurements made during the period December 2006 to June 2008 are considered for evaluation. Uncorrected ionization readings of EC for all the radiation beams over the entire period were within 2% showing the consistency of measurements. Absorbed doses estimated by EC were in good agreement with in-water calibrations within 2% for photons and electron beams. The present results suggest that extrapolation chambers can be considered as an independent measuring system for absorbed dose in addition to Farmer type ion chambers. In the absence of standard beam quality (Co-60 radiations as reference Quality for Nd,water) the possibility of keeping EC as Primary Standards for absorbed dose calibrations in high energy radiation beams from linacs should be explored. As there are neither Standard Laboratories nor SSDL available in our country, we look forward to keep EC as Local Standard for hospital chamber calibrations. We are also participating in the IAEA mailed TLD intercomparison programme for quality audit of existing status of radiation dosimetry in high energy linac beams. The performance of EC has to be confirmed with cobalt-60 beams by a separate study, as linacs are susceptible for minor variations in dose

  19. Extrapolation chamber mounted on perspex for calibration of high energy photon and electron beams from a clinical linear accelerator

    PubMed Central

    Ravichandran, R.; Binukumar, J. P.; Sivakumar, S. S.; Krishnamurthy, K.; Davis, C. A.

    2009-01-01

    The objective of the present study is to establish radiation standards for absorbed doses, for clinical high energy linear accelerator beams. In the nonavailability of a cobalt-60 beam for arriving at Nd, water values for thimble chambers, we investigated the efficacy of perspex mounted extrapolation chamber (EC) used earlier for low energy x-rays and beta dosimetry. Extrapolation chamber with facility for achieving variable electrode separations 10.5mm to 0.5mm using micrometer screw was used for calibrations. Photon beams 6 MV and 15 MV and electron beams 6 MeV and 15 MeV from Varian Clinac linacs were calibrated. Absorbed Dose estimates to Perspex were converted into dose to solid water for comparison with FC 65 ionisation chamber measurements in water. Measurements made during the period December 2006 to June 2008 are considered for evaluation. Uncorrected ionization readings of EC for all the radiation beams over the entire period were within 2% showing the consistency of measurements. Absorbed doses estimated by EC were in good agreement with in-water calibrations within 2% for photons and electron beams. The present results suggest that extrapolation chambers can be considered as an independent measuring system for absorbed dose in addition to Farmer type ion chambers. In the absence of standard beam quality (Co-60 radiations as reference Quality for Nd,water) the possibility of keeping EC as Primary Standards for absorbed dose calibrations in high energy radiation beams from linacs should be explored. As there are neither Standard Laboratories nor SSDL available in our country, we look forward to keep EC as Local Standard for hospital chamber calibrations. We are also participating in the IAEA mailed TLD intercomparison programme for quality audit of existing status of radiation dosimetry in high energy linac beams. The performance of EC has to be confirmed with cobalt-60 beams by a separate study, as linacs are susceptible for minor variations in dose

  20. Stable Electron Beams With Low Absolute Energy Spread From a LaserWakefield Accelerator With Plasma Density Ramp Controlled Injection

    SciTech Connect

    Geddes, Cameron G.R.; Cormier-Michel, E.; Esarey, E.; Leemans,W.P.; Nakamura, K.; Panasenko, D.; Plateau, Guillaume R.; Schroeder, CarlB.; Toth, Csaba; Cary, J.R.

    2007-06-25

    Laser wakefield accelerators produce accelerating gradientsup to hundreds of GeV/m, and recently demonstrated 1-10 MeV energy spreadat energies up to 1 GeV using electrons self-trapped from the plasma.Controlled injection and staging may further improve beam quality bycircumventing tradeoffs between energy, stability, and energyspread/emittance. We present experiments demonstrating production of astable electron beam near 1 MeV with hundred-keV level energy spread andcentral energy stability by using the plasma density profile to controlselfinjection, and supporting simulations. Simulations indicate that suchbeams can be post accelerated to high energies,potentially reducingmomentum spread in laser acceleratorsby 100-fold or more.

  1. Diamond detector in absorbed dose measurements in high-energy linear accelerator photon and electron beams.

    PubMed

    Ravichandran, Ramamoorthy; Binukumar, John Pichy; Al Amri, Iqbal; Davis, Cheriyathmanjiyil Antony

    2016-03-08

    Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue-equivalent properties. We investigated a commercially available 'microdiamond' detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1mm, thickness 1 x10(-3) mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17% (1 SD) (n = 11). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stop-ping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long-term stability and reproducibility. Based on micro-dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance.

  2. High-energy-density electron beam from interaction of two successive laser pulses with subcritical-density plasma

    NASA Astrophysics Data System (ADS)

    Wang, J. W.; Yu, W.; Yu, M. Y.; Xu, H.; Ju, J. J.; Luan, S. X.; Murakami, M.; Zepf, M.; Rykovanov, S.

    2016-02-01

    It is shown by particle-in-cell simulations that a narrow electron beam with high energy and charge density can be generated in a subcritical-density plasma by two consecutive laser pulses. Although the first laser pulse dissipates rapidly, the second pulse can propagate for a long distance in the thin wake channel created by the first pulse and can further accelerate the preaccelerated electrons therein. Given that the second pulse also self-focuses, the resulting electron beam has a narrow waist and high charge and energy densities. Such beams are useful for enhancing the target-back space-charge field in target normal sheath acceleration of ions and bremsstrahlung sources, among others.

  3. Comparisons of the Codes of Practice IAEA TRS 277 and TRS 398: High Energy Photons and Electron Beams

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Castillo, J. G.; Torres-Calderón, A.; Fragoso-Valdéz, F. R.; Álvarez-Romero, J. T.

    2004-09-01

    This work presents the calibration for: 6, 8, 10, 12, 14, 15 and 18 MeV electron beams, also to 6 and 15 MV photons beams. Beams that are generated by an accelerator Elekta Linac SL 18. The calibration is performed in terms of absorbed dose to water Dw. It is determined by two different protocols: the code of practice of the International Atomic Energy Agency (IAEA) TRS 277 for ionization chambers calibrated on air kerma NK, and the code of practice TRS 398 for ionization chambers calibrated on absorbed dose to water ND,W. Two independent dosimeters were used with two ionization chambers each one, respectively. The first one, a dosimeter PTW model UNIDOS with Markus type chamber (plane parallel) for electrons, and Farmer type chamber (cylindrical) for photons, both chambers calibrated in NK. The second dosimeter Scanditronix model DOSE 1 with plane parallel chamber (electrons) and cylindrical chamber (photons), both chambers calibrated in terms of ND,W. In the case of photon beams, the TPR was measured for 6 and 15 MV, also the profiles were determined in order to verify the flatness and symmetry of the beam: ±3%. The quality for electrons beams were estimated by means of the Dmax, R80, R50 and Rp. The results obtained for the absorbed dose quotients DW,Q(dmax)277398 are: Electrons, 0.976⩽ DW,Q(dmax)277398⩽ 1.001; Photons: 1.001 ⩽ DW,Q(dmax)277398 ⩽ 1.003.

  4. Surface hardening of a ductile-cast iron roll using high-energy electron beams

    NASA Astrophysics Data System (ADS)

    Suh, Dongwoo; Lee, Sunghak; Koo, Yangmo; Kwon, Soon-Ju

    1997-07-01

    The effects of high-energy electron beam irradiation on surface hardening and microstructural modification in a ductile cast iron (DCI) roll are investigated in this study. The DCI roll samples were irradiated by using an electron accelerator (1.4 MeV), and then their microstructures and hardnesses were examined. Upon irradiation, the unirradiated microstructure containing graphites and the tempered bainite matrix was changed to martensite, ledeburite, and retained austenite, together with the complete or partial dissolution of graphites. This microstructural modification improved greatly the surface hardness due to transformation of martensite whose amount and type were determined by heat input during irradiation. In order to investigate these complex microstructures, a simulation test including thermal cycles of abrupt heating and quenching was carried out. The simulation results indicated that the irradiated surface was heated up to about 1100 °C to 1200 °C and then quenched to room temperature, which was enough to obtain surface hardening through martensitic transformation. Thermal analysis of the irradiated surface layer was also carried out using a finite difference method to understand the surface hardening of the DCI roll and to compare with the simulation test results.

  5. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    NASA Astrophysics Data System (ADS)

    Bakar, Khomsaton Abu; Ahmad, Pauzi; Zulkafli, Hashim, Siti A'aisah

    2014-09-01

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  6. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    SciTech Connect

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A'aisah; Ahmad, Pauzi

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  7. 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.

  8. Imaging of high-energy electron beam profile with optical diffraction radiation

    NASA Astrophysics Data System (ADS)

    Xiang, Dao; Huang, Wen-Hui; Lin, Yu-Zheng

    2007-06-01

    Optical transition radiation (OTR) has been widely used in electron beam profile imaging. Optical diffraction radiation (ODR) has recently been used to measure the electron beam’s transverse size with the angular distribution. Because of the close relationship between OTR and ODR, it is natural to ask whether ODR could be used to image the beam profile as is done with OTR. In this paper, the image formation process is investigated as a two-dimensional (2D) convolution. The image formed with ODR as a single electron passes through a circular aperture, through a rectangular slit, and beneath a semi-infinite plane is studied from first principle and taken to be the point spread function (PSF) of the imaging system. It is found that, unlike the OTR case, the PSF of ODR is space variant and largely depends on the shape of the ODR target. With this characteristic, the beam image formed with ODR differs greatly from the real beam profile, and the deconvolution process is generally needed in order to retrieve the real beam distribution from the ODR image. The possibility of using an image formed with ODR from a rectangular slit and a semi-infinite plane to determine beam profile in the direction parallel to the edge of the slit or plane and monitoring the beam’s position are estimated. The theoretical prediction is compared to recently reported experimental results and a qualitative agreement is achieved.

  9. Development of the Science and Technology of Electron Beam Pumped KrF Lasers for Fusion Energy

    NASA Astrophysics Data System (ADS)

    Sethian, John

    2002-11-01

    Electron beam pumped krypton fluoride (KrF) lasers are an attractive driver for inertial fusion energy. They have demonstrated very high beam quality, which is essential for reducing imprint in direct drive targets. Their short wavelength (248 nm) mitigates the growth of plasma instabilities. And they have the potential to meet the fusion needs for repetition rate, efficiency, and cost. This paper reviews the development of e-beam pumped KrF lasers. It will include a description of the fundamental physics and technology, as well as the challenges in developing a fusion system. Although KrF laser development is a multi-disciplinary endeavor, this talk will emphasize areas of interest to plasma physicists: electron beams, KrF kinetics, and pulsed power. The paper will describe experiments and modeling that has identified and mitigated instabilities in the electron beam. It will describe the electron beam propagation experiments, the supporting 3D parallel PIC codes, and how these have been used to design systems for maximum electron energy deposition into the laser gas. KrF kinetics modeling will be discussed. These newly developed time dependent codes can predict the output of several experiments operating under significantly different conditions. They are now being used as a design tool to predict the performance of future KrF systems. Finally, the talk will discuss the development of the pulsed power needed to drive the electron beams. This includes conventional gas switched systems for single shot devices together with the recently demonstrated all solid state switches that have the promise to meet the fusion requirements. The talk will be cast in context of the large, single shot KrF lasers built in the 1990's such as Nike (NRL-US), Ashura (Japan), and Titania (UK), as well as the Electra 700 J, 5 Hz rep-rate laser that is currently under development at NRL.

  10. 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.

  11. Optimization of 3D conformal electron beam therapy in inhomogeneous media by concomitant fluence and energy modulation

    NASA Astrophysics Data System (ADS)

    Åsell, Mats; Hyödynmaa, Simo; Gustafsson, Anders; Brahme, Anders

    1997-11-01

    The possibilities of using simultaneous fluence and energy modulation techniques in electron beam therapy to shape the dose distribution and almost eliminate the influences of tissue inhomogeneities have been investigated. By using a radiobiologically based optimization algorithm the radiobiological properties of the tissues can be taken into account when trying to find the best possible dose delivery. First water phantoms with differently shaped surfaces were used to study the effect of surface irregularities. We also studied water phantoms with internal inhomogeneities consisting of air or cortical bone. It was possible to improve substantially the dose distribution by fluence modulation in these cases. In addition to the fluence modulation the most suitable single electron energy in each case was also determined. Finally, the simultaneous use of several preselected electron beam energies was also tested, each with an individually optimized fluence profile. One to six electron energies were used, resulting in a slow improvement in complication-free cure with increasing number of beam energies. To apply these techniques to a more clinically relevant situation a post-operative breast cancer patient was studied. For simplicity this patient was treated with only one anterior beam portal to clearly illustrate the effect of inhomogeneities like bone and lung on the dose distribution. It is shown that by using fluence modulation the influence of dose inhomogeneities can be significantly reduced. When two or more electron beam energies with individually optimized fluence profiles are used the dose conformality to the internal target volume is further increased, particularly for targets with complex shapes.

  12. Optimization of 3D conformal electron beam therapy in inhomogeneous media by concomitant fluence and energy modulation.

    PubMed

    Asell, M; Hyödynmaa, S; Gustafsson, A; Brahme, A

    1997-11-01

    The possibilities of using simultaneous fluence and energy modulation techniques in electron beam therapy to shape the dose distribution and almost eliminate the influences of tissue inhomogeneities have been investigated. By using a radiobiologically based optimization algorithm the radiobiological properties of the tissues can be taken into account when trying to find the best possible dose delivery. First water phantoms with differently shaped surfaces were used to study the effect of surface irregularities. We also studied water phantoms with internal inhomogeneities consisting of air or cortical bone. It was possible to improve substantially the dose distribution by fluence modulation in these cases. In addition to the fluence modulation the most suitable single electron energy in each case was also determined. Finally, the simultaneous use of several preselected electron beam energies was also tested, each with an individually optimized fluence profile. One to six electron energies were used, resulting in a slow improvement in complication-free cure with increasing number of beam energies. To apply these techniques to a more clinically relevant situation a post-operative breast cancer patient was studied. For simplicity this patient was treated with only one anterior beam portal to clearly illustrate the effect of inhomogeneities like bone and lung on the dose distribution. It is shown that by using fluence modulation the influence of dose inhomogeneities can be significantly reduced. When two or more electron beam energies with individually optimized fluence profiles are used the dose conformality to the internal target volume is further increased, particularly for targets with complex shapes.

  13. EMERGING TECHNOLOGY BULLETIN: REMOVAL OF PHENOL FROM AQUEOUS SOLUTIONS USING HIGH ENERGY ELECTRON BEAM IRRADIATION

    EPA Science Inventory

    Irradiation of aqueous solutions with high-energy electrons results in the formation of the aqueous electron, hydrogen radical, H-, and the hydroxyl radical, OH-. These reactive transient species initiate chemical reactions capable of destroying organic compounds in aqueous solut...

  14. Measurement and simulation of the impact of coherent synchrotron radiation on the Jefferson Laboratory energy recovery linac electron beam

    NASA Astrophysics Data System (ADS)

    Hall, C. C.; Biedron, S. G.; Edelen, A. L.; Milton, S. V.; Benson, S.; Douglas, D.; Li, R.; Tennant, C. D.; Carlsten, B. E.

    2015-03-01

    In an experiment conducted on the Jefferson Laboratory IR free-electron laser driver, the effects of coherent synchrotron radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR recirculator. Here we examine the impact of CSR on the average energy loss as a function of bunch compression as well as the impact of CSR on the energy spectrum of the bunch. Simulation of beam dynamics in the machine, including the one-dimensional CSR model, shows very good agreement with the measured effect of CSR on the average energy loss as a function of compression. Finally, a well-defined structure is observed in the energy spectrum with a feature in the spectrum that varies as a function of the compression. This effect is examined in simulations, as well, and a simple explanation for the variation is proposed.

  15. Measurement and simulation of the impact of coherent synchrotron radiation on the Jefferson Laboratory energy recovery linac electron beam

    SciTech Connect

    Hall, C C.; Biedron, S G.; Edelen, A L.; Milton, S V.; Benson, S; Douglas, D; Li, R; Tennant, C D.; Carlsten, B E.

    2015-03-09

    In an experiment conducted on the Jefferson Laboratory IR free-electron laser driver, the effects of coherent synchrotron radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR recirculator. Here we examine the impact of CSR on the average energy loss as a function of bunch compression as well as the impact of CSR on the energy spectrum of the bunch. Simulation of beam dynamics in the machine, including the one-dimensional CSR model, shows very good agreement with the measured effect of CSR on the average energy loss as a function of compression. Finally, a well-defined structure is observed in the energy spectrum with a feature in the spectrum that varies as a function of the compression. This effect is examined in simulations, as well, and a simple explanation for the variation is proposed.

  16. Damage and strain in single-layer graphene induced by very-low-energy electron-beam irradiation

    SciTech Connect

    Murakami, Katsuhisa; Fujita, Jun-ichi; Kadowaki, Takuya

    2013-01-28

    From the analysis of the ratio of D peak intensity to G peak intensity in Raman spectroscopy, electron beam irradiation with energies of 100 eV was found to induce damage in single-layer graphene. The damage becomes larger with decreasing electron beam energy. Internal strain in graphene induced by damage under irradiation is further evaluated based on G peak shifts. The dose-dependent internal strain was approximately 2.22% cm{sup 2}/mC at 100 eV and 2.65 Multiplication-Sign 10{sup -2}% cm{sup 2}/mC at 500 eV. The strain induced by the irradiation showed strong dependence on electron energy.

  17. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  18. Portal verification of high-energy electron beams using their photon contamination by film-cassette systems.

    PubMed

    Geyer, Peter; Baus, Wolfgang W; Baumann, Michael

    2006-01-01

    Though electron beams are widely used in radiotherapy, their verification is not well established in clinical practice. The present study compares the suitability of several sensitive film-cassette systems for electron-portal verification by contaminating photons. The characteristics of the optical density curves of film-cassette combinations were determined by exposing them to the bremsstrahlung contamination of a variety of electron beams. Using a Las-Vegas Phantom the spatial low-contrast resolution of the combinations was investigated. The absorbed dose rates due to the contaminant photons were measured for different geometric conditions. Suitable film-cassette combinations were found for portal verification of all usual electron energies. The best image quality was obtained using the EC film and the EC-L cassettes. For electron energies higher than 6 MeV some film-cassette combinations are suitable to verify abutted electron and photon portals using the same film sheet. The verification of electron portals and of abutted electron-photon portals can be performed by sensitive film-cassette systems with an image quality comparable to photon-beam verification.

  19. Study of the new CSAR62 positive tone electron-beam resist at 40 keV electron energy

    NASA Astrophysics Data System (ADS)

    Andok, R.; Bencurova, A.; Vutova, K.; Koleva, E.; Nemec, P.; Hrkut, P.; Kostic, I.; Mladenov, G.

    2016-03-01

    One of the few "top-down" methods for nano-device fabrication is the electron-beam lithography, which allows flexible patterning of various structures with a nanoscale resolution down to less than 10 nm. Thinner, more etching durable, and more sensitive e-beam resists are required for the better control, linearity, and uniformity of critical dimensions of structures for nano-device fabrication. Within the last decade, researchers have made significant efforts to improve the resolution of the nanoscale e-beam lithography. The resist material properties are an important factor governing the resolution. Only the e-beam resist ZEP 520 of the Japanese manufacturer ZEON is characterized by relatively good properties and thus meets most users' expectations. This paper deals with the investigation and simulation of the characteristics of the new less-expensive AR-P 6200 (CSAR 62) positive e-beam resist (available since May 2013, manufactured by Allresist GmbH company).

  20. Relativistic Electron Beams Above Thunderclouds

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  1. High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators

    DOEpatents

    Janke, Christopher J.; Lopata, Vincent J.; Havens, Stephen J.; Dorsey, George F.; Moulton, Richard J.

    1999-01-01

    A mixture of epoxy resins such as a semi-solid triglycidyl ether of tris (hydroxyphenyl) methane and a low viscosity bisphenol A glycidyl ether and a cationic photoinitiator such as a diaryliodonium salt is cured by irradiating with a dosage of electron beams from about 50 to about 150 kGy, forming a cross-linked epoxy resin polymer.

  2. High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators

    DOEpatents

    Janke, C.J.; Lopata, V.J.; Havens, S.J.; Dorsey, G.F.; Moulton, R.J.

    1999-03-02

    A mixture of epoxy resins such as a semi-solid triglycidyl ether of tris (hydroxyphenyl) methane and a low viscosity bisphenol A glycidyl ether and a cationic photoinitiator such as a diaryliodonium salt is cured by irradiating with a dosage of electron beams from about 50 to about 150 kGy, forming a cross-linked epoxy resin polymer.

  3. Electron beam polarimetry

    SciTech Connect

    Sinclair, C.K.

    1998-12-01

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

  4. Electron beam polarimetry

    NASA Astrophysics Data System (ADS)

    Sinclair, Charles K.

    1998-12-01

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

  5. Neutralization of space charge on high-current low-energy ion beam by low-energy electrons supplied from silicon based field emitter arrays

    SciTech Connect

    Gotoh, Yasuhito; Tsuji, Hiroshi; Taguchi, Shuhei; Ikeda, Keita; Kitagawa, Takayuki; Ishikawa, Junzo; Sakai, Shigeki

    2012-11-06

    Neutralization of space charge on a high-current and low-energy ion beam was attempted to reduce the divergence with an aid of low-energy electrons supplied from silicon based field emitter arrays (Si-FEAs). An argon ion beam with the energy of 500 eV and the current of 0.25 mA was produced by a microwave ion source. The initial beam divergence and the emittance were measured at the entrance of the analysis chamber in order to estimate the intrinsic factors for beam divergence. The current density distribution of the beam after transport of 730 mm was measured by a movable Faraday cup, with and without electron supply from Si-FEAs. A similar experiment was performed with tungsten filaments as an electron source. The results indicated that the electron supply from FEA had almost the same effect as the thermionic filament, and it was confirmed that both electron sources can neutralize the ion beam.

  6. Electric and Magnetic Field Measurements in High Energy Electron Beam Diode Plasmas using Optical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Johnston, Mark; Patel, Sonal; Kiefer, Mark; Biswas, S.; Doron, R.; Stambulchik, E.; Bernshtam, V.; Maron, Yitzhak

    2016-10-01

    The RITS accelerator (5-11MV, 100-200kA) at Sandia National Laboratories is being used to evaluate the Self-Magnetic Pinch (SMP) diode as a potential flash x-ray radiography source. This diode consists of a small, hollowed metal cathode and a planar, high atomic mass anode, with a small vacuum gap of approximately one centimeter. The electron beam is focused, due to its self-field, to a few millimeters at the target, generating bremsstrahlung x-rays. During this process, plasmas form on the electrode surfaces and propagate into the vacuum gap, with a velocity of a 1-10 cm's/microseconds. These plasmas are measured spectroscopically using a Czerny-Turner spectrometer with a gated, ICCD detector, and input optical fiber array. Local magnetic and electric fields of several Tesla and several MV/cm were measured through Zeeman splitting and Stark shifting of spectral lines. Specific transitions susceptible to quantum magnetic and electric field effects were utilized through the application of dopants. Data was analyzed using detailed, time-dependent, collisional-radiative (CR) and radiation transport modeling. Recent results will be presented. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  7. Optical and chemical behaviors of CR-39 and Makrofol plastics under low-energy electron beam irradiation

    NASA Astrophysics Data System (ADS)

    El-Saftawy, Ashraf Ali; Abd El Aal, Saad Ahmed; Hassan, Nabil Mohamed; Abdelrahman, Moustafa Mohamed

    2016-07-01

    In this study, CR-39 and Makrofol plastic nuclear track detectors were irradiated with low-energy electron beams to study the effect of the induced changes on their optical and chemical properties. Surface chemical changes were recorded by Fourier transform infrared (FTIR) spectroscopy, which showed successive degradation and crosslinking for CR-39 and decomposition for Makrofol. The optical band gap was determined by UV-vis spectroscopy. Also, the parameters of carbon cluster formation and disordering (Urbach’s energy) occurring on plastic surfaces were examined. The intrinsic viscosity changes were investigated as well. As a result, low-energy electron beams were found to be useful for the control of many properties of the surfaces of the investigated detectors.

  8. An annular high-current electron beam with an energy spread in a coaxial magnetically insulated diode

    SciTech Connect

    Grishkov, A. A. Pegel, I. V.

    2013-11-15

    An elementary theory of an annular high-current electron beam in a uniform transport channel and a coaxial magnetically insulated diode is generalized to the case of counterpropagating electron beams with a spread over kinetic energies. Expressions for the sum of the absolute values of the forward and backward currents in a uniform transport channel and for the flux of the longitudinal component of the generalized momentum in a coaxial magnetically insulated diode as functions of the maximum electron kinetic energy are derived for different values of the relative width of the energy distribution function. It is shown that, in a diode with an expanding transport channel and a virtual cathode limiting the extracted current, counterpropagating particle flows are established between the cathode and the virtual cathode within a certain time interval after the beginning of electron emission. The accumulation of electrons in these flows is accompanied by an increase in their spread over kinetic energies and the simultaneous decrease in the maximum kinetic energy. The developed model agrees with the results of particle-in-cell simulations performed using the KARAT and OOPIC-Pro codes.

  9. Energy deposition evaluation for ultra-low energy electron beam irradiation systems using calibrated thin radiochromic film and Monte Carlo simulations

    SciTech Connect

    Matsui, S. Mori, Y.; Nonaka, T.; Hattori, T.; Kasamatsu, Y.; Haraguchi, D.; Watanabe, Y.; Uchiyama, K.; Ishikawa, M.

    2016-05-15

    For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films and Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management.

  10. Polarized electron beams at SLAC

    SciTech Connect

    Moffeit, K.C.

    1992-11-01

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

  11. Polarized electron beams at SLAC

    SciTech Connect

    Moffeit, K.C.

    1992-11-01

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

  12. Electromagnetic radiation and nonlinear energy flow in an electron beam-plasma system

    NASA Technical Reports Server (NTRS)

    Whelan, D. A.; Stenzel, R. L.

    1985-01-01

    It is shown that the unstable electron-plasma waves of a beam-plasma system can generate electromagnetic radiation in a uniform plasma. The generation mechanism is a scattering of the unstable electron plasma waves off ion-acoustic waves, producing electromagnetic waves whose frequency is near the local plasma frequency. The wave vector and frequency matching conditions of the three-wave mode coupling are experimentally verified. The electromagnetic radiation is observed to be polarized with the electric field parallel to the beam direction, and its source region is shown to be localized to the unstable plasma wave region. The frequency spectrum shows negligible intensity near the second harmonic of the plasma frequency. These results suggest that the observed electromagnetic radiation of type III solar bursts may be generated near the local plasma frequency and observed downstream where the wave frequency is near the harmonic of the plasma frequency.

  13. Electromagnetic radiation and nonlinear energy flow in an electron beam-plasma system

    NASA Technical Reports Server (NTRS)

    Whelan, D. A.; Stenzel, R. L.

    1985-01-01

    It is shown that the unstable electron-plasma waves of a beam-plasma system can generate electromagnetic radiation in a uniform plasma. The generation mechanism is a scattering of the unstable electron plasma waves off ion-acoustic waves, producing electromagnetic waves whose frequency is near the local plasma frequency. The wave vector and frequency matching conditions of the three-wave mode coupling are experimentally verified. The electromagnetic radiation is observed to be polarized with the electric field parallel to the beam direction, and its source region is shown to be localized to the unstable plasma wave region. The frequency spectrum shows negligible intensity near the second harmonic of the plasma frequency. These results suggest that the observed electromagnetic radiation of type III solar bursts may be generated near the local plasma frequency and observed downstream where the wave frequency is near the harmonic of the plasma frequency.

  14. Numerical Analysis of the Measurement of Near-Beam Electron Cloud Density in Field-Free Region at KEK B-Factory Low-Energy Ring

    NASA Astrophysics Data System (ADS)

    Jain, Puneet; Fukuma, Hitoshi; Kanazawa, Ken-ichi; Suetsugu, Yusuke

    2010-11-01

    A large number of electrons in the so-called electron cloud are accumulated in beam chambers in positron storage rings. These electrons interact with the beam and can make the beam unstable. The density information of the electron cloud near the beam is therefore fundamental for studying beam instability and mitigation techniques related to the electron cloud. Recently, a method to measure the density of the electron cloud near the beam has been proposed by Kanazawa et al. The method enables the measurement of high-energy electrons selectively using a retarding field analyzer located on a chamber wall, noting that the electrons near the beam receive a strong kick by the beam. They calculated the density of the electron cloud simply assuming that the electrons that receive a kick are stationary. We examined the measurement technique in detail using a new computer code developed by us. The analysis showed that the volume near the beam occupied by the detected electrons, i.e., the observed volume, was strongly deformed owing to the horizontal velocity of the electrons; nevertheless this volume calculated assuming that the stationary electrons can still be used for calculating the density of the electron cloud in their measurement conditions.

  15. High energy beam lines

    NASA Astrophysics Data System (ADS)

    Marchetto, M.; Laxdal, R. E.

    2014-01-01

    The ISAC post accelerator comprises an RFQ, DTL and SC-linac. The high energy beam lines connect the linear accelerators as well as deliver the accelerated beams to two different experimental areas. The medium energy beam transport (MEBT) line connects the RFQ to the DTL. The high energy beam transport (HEBT) line connects the DTL to the ISAC-I experimental stations (DRAGON, TUDA-I, GPS). The DTL to superconducting beam (DSB) transport line connects the ISAC-I and ISAC-II linacs. The superconducting energy beam transport (SEBT) line connects the SC linac to the ISAC-II experimental station (TUDA-II, HERACLES, TIGRESS, EMMA and GPS). All these lines have the function of transporting and matching the beams to the downstream sections by manipulating the transverse and longitudinal phase space. They also contain diagnostic devices to measure the beam properties.

  16. 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.

  17. 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.

  18. 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

  19. [Dose distributions of fast electrons with an energy of 7-24 Mev in electromagnetic beam formation].

    PubMed

    Shambulov, R S; Khvan, G V; Saĭbekov, T S; Azhigaliev, N A; Shuinbekov, A D

    1983-03-01

    The formation of a wide beam is found necessary for a clinical application of a fast electron beam. A method of formation using thin dispersion foils is the most common one. An electromagnetic method of formation has been worked out, and dose distributions of fast electrons formed by this method have been compared in the tissue equivalent medium with those formed with the help of dispersion foils. The effect of some of the individual units of the forming device in these two methods of formation has been assessed. The experiment was conducted on medical beta-trons B-15 and B-5M-25 manufactured in the USSR. The depth dose distributions of fast electrons along the beam central axis in the electromagnetic formation for electrons with an energy of 7-24 MEV, field 8 X 10 cm and DSS = 90 cm are presented. It has been established that the beam intensity in the electromagnetic formation is higher than in the utilization of dispersion foils. Depth dose distribution is better in the electromagnetic formation than in the utilization of dispersion foils.

  20. Phase composition in NiTi near-surface layers after electron beam treatment and its variation depending on beam energy density

    SciTech Connect

    Ostapenko, Marina G.; Meisner, Ludmila L.; Lotkov, Aleksandr I. E-mail: egu@ispms.tsc.ru; Gudimova, Ekaterina Y. E-mail: egu@ispms.tsc.ru

    2014-11-14

    In the work, we study the mechanisms of structural phase state formation in NiTi surface layers after low-energy pulsed electron beam irradiation depending on the electron beam energy density. It is revealed that after electron beam treatment of the NiTi specimens at energy densities E{sub 1} = 15 J/cm{sup 2}, E{sub 2} = 20 J/cm{sup 2}, and E{sub 3} = 30 J/cm{sup 2}, a series of effects is observed: the absence of the Ti2Ni phase and the presence of new peaks correspond to the B19′ martensite phase with monoclinic structure. Estimation of the relative volume content of the B2 and B19′ phases from the total intensity of their peaks shows that the percentage of the martensite phase increases from ∼5 vol.% in the NiTi specimen irradiated at E{sub 1} = 15 J/cm{sup 2} to ∼80 vol.% in the NiTi specimen irradiated at E{sub 3} = 30 J/cm{sup 2}. It is found that in the NiTi specimens irradiated at E ≤ 20 J/cm{sup 2}, the layer that contains a martensite phase resides not on the surface but at some depth from it.

  1. MgH2 → Mg phase transformation driven by a high-energy electron beam: An in situ transmission electron microscopy study

    NASA Astrophysics Data System (ADS)

    Paik, B.; Jones, I. P.; Walton, A.; Mann, V.; Book, D.; Harris, I. R.

    2010-01-01

    The dynamics of a phase change have been studied using the electron beam in a transmission electron microscope to transform MgH2 into Mg. The study involved selected-area diffraction and electron-energy-loss spectroscopy (EELS). The orientation relation ( ? and ? ), obtained from the electron diffraction study, has been used to propose a model for the movements of magnesium atoms during the phase change. The in situ EELS results have been compared with the existing H-desorption model. The study aims to describe the sorption dynamics of hydrogen in MgH2, which is a base material for a number of promising hydrogen storage systems.

  2. Electron beam dose calculations.

    PubMed

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

    1981-05-01

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

  3. Determination of Energy of a Clinical Electron Beam as Part of a Routine Quality Assurance and Audit System

    NASA Astrophysics Data System (ADS)

    Hernández-Bello, Jimmy; D'Souza, Derek; Rossenberg, Ivan

    2002-08-01

    A method to determine the electron beam energy and an electron audit based on the current IPEM electron Code of Practice has been devised. During the commissioning on the new Varian 2100CD linear accelerator in The Middlesex Hospital, two methods were devised for the determination of electron energy. The first method involves the use of a two-depth method, whereby the ratio of ionisation (presented as a percentage) measured by an ion chamber at two depths in solid water is used to compare against the baseline ionisation depth value for that energy. The second method involves the irradiation of an X-ray film in solid water to obtain a depth dose curve and, hence determine the half value depth and practical range of the electrons. The results showed that the two-depth method has a better accuracy, repeatability, reliability and consistency than the X-ray method. The results for the electron audit showed that electron absolute outputs are obtained from ionisation measurements in solid water, where the energy-range parameters such as practical range and the depth at which ionisation is 50% of that at the maximum for the depth-ionisation curve are determined.

  4. Electron stripping processes of H{sup −} ion beam in the 80 kV high voltage extraction column and low energy beam transport line at LANSCE

    SciTech Connect

    Draganic, I. N.

    2016-02-15

    Basic vacuum calculations were performed for various operating conditions of the Los Alamos National Neutron Science H{sup −} Cockcroft-Walton (CW) injector and the Ion Source Test Stand (ISTS). The vacuum pressure was estimated for both the CW and ISTS at five different points: (1) inside the H{sup −} ion source, (2) in front of the Pierce electrode, (3) at the extraction electrode, (4) at the column electrode, and (5) at the ground electrode. A static vacuum analysis of residual gases and the working hydrogen gas was completed for the normal ion source working regime. Gas density and partial pressure were estimated for the injected hydrogen gas. The attenuation of H{sup −} beam current and generation of electron current in the high voltage acceleration columns and low energy beam transport lines were calculated. The interaction of H{sup −} ions on molecular hydrogen (H{sub 2}) is discussed as a dominant collision process in describing electron stripping rates. These results are used to estimate the observed increase in the ratio of electrons to H{sup −} ion beam in the ISTS beam transport line.

  5. Electron stripping processes of H- ion beam in the 80 kV high voltage extraction column and low energy beam transport line at LANSCE

    NASA Astrophysics Data System (ADS)

    Draganic, I. N.

    2016-02-01

    Basic vacuum calculations were performed for various operating conditions of the Los Alamos National Neutron Science H- Cockcroft-Walton (CW) injector and the Ion Source Test Stand (ISTS). The vacuum pressure was estimated for both the CW and ISTS at five different points: (1) inside the H- ion source, (2) in front of the Pierce electrode, (3) at the extraction electrode, (4) at the column electrode, and (5) at the ground electrode. A static vacuum analysis of residual gases and the working hydrogen gas was completed for the normal ion source working regime. Gas density and partial pressure were estimated for the injected hydrogen gas. The attenuation of H- beam current and generation of electron current in the high voltage acceleration columns and low energy beam transport lines were calculated. The interaction of H- ions on molecular hydrogen (H2) is discussed as a dominant collision process in describing electron stripping rates. These results are used to estimate the observed increase in the ratio of electrons to H- ion beam in the ISTS beam transport line.

  6. The dose rate dependence of synthetic diamond detectors in the relative dosimetry of high-energy electron therapy beams

    NASA Astrophysics Data System (ADS)

    Ade, N.; Nam, T. L.; Derry, T. E.; Mhlanga, S. H.

    2014-05-01

    Evaluation of the linear response of a radiation detector with absorbed dose rate should be of paramount importance in clinical dosimetry. As modelled by Fowler, electrical conductivity, σ, of a solid-state detector and absorbed dose rate, Dr, are related by σ~DrΔ where Δ is the linearity index. The detector is thus independent of dose rate if Δ is unity. This contribution investigates and evaluates the dependence of Δ of synthetic diamond detectors of various types on therapy electron energy and its influence in relative electron dosimetry with the aim of selecting a suitable crystal. The study was conducted initially on one HPHT and eight CVD synthesised diamonds of optical grade (OG) and detector grade (DG) qualities using 6-14 MeV electron therapy beams. For quality control, the diamond specimens were characterised by Raman spectroscopy and electron spin resonance (ESR). Values of Δ ranging between 0.79 and 1.03 were obtained for all the nine diamond detectors at 1000 V/cm for 7 and 12 MeV electron beams. Whereas the Δ values of the HPHT diamond were found not to vary with the electron energies, those of three CVD samples of a given class varied with the electron energies within 2%. In addition, a very strong variation of about 9% was observed for two OG crystals of another class. The Δ values were found to decrease with increasing dose rate and there was a tendency for the Δ values to change with defect levels present within the crystals. Due to the independence of the HPHT diamond's Δ values on electron energy and its better stability of response to radiation, a small-size HPHT crystal was then evaluated of its potential applications in small radiation fields. Relative dose distributions measured with the diamond probe on exposure to 6, 12 and 14 MeV electron beams between 1×1 cm2 and 10×10 cm2 fields were compared with those obtained with reference ion chambers and a Dosimetry Diode E. The results showed that with careful selection of a suitable

  7. Multicomponent measurements of the Jefferson Lab energy recovery linac electron beam using optical transition and diffraction radiation

    NASA Astrophysics Data System (ADS)

    Holloway, M. A.; Fiorito, R. B.; Shkvarunets, A. G.; O'Shea, P. G.; Benson, S. V.; Douglas, D.; Evtushenko, P.; Jordan, K.

    2008-08-01

    High brightness electron accelerators, such as energy recovery linacs (ERL), often have complex particle distributions that can create difficulties in beam transport as well as matching to devices such as wigglers used to generate radiation from the beam. Optical transition radiation (OTR), OTR interferometry (OTRI), and optical diffraction-transition radiation interferometry (ODTRI) have proven to be effective tools for diagnosing both the spatial and angular distributions of charged particle beams. OTRI and ODTRI have been used to measure rms divergences, and optical transverse phase space mapping has been demonstrated using OTRI. In this work we present the results of diagnostic experiments using OTR and optical diffraction radiation conducted at the Jefferson Laboratory’s 115 MeV ERL which show the presence of two separate components within the beam’s spatial and angular distributions. By assuming a correlation between the spatial and angular features, we estimate an rms emittance value for each of the two components.

  8. Energy- and Intensity-Modulated Electron Beam for Breast Cancer Treatment

    DTIC Science & Technology

    1999-10-01

    collimator conformal radiation therapy. Int. J. Radiat. Oncol. Biol. Phys. 25 :171-179, 1993. 6. JM Galvin, X Chen, and RM Smith. Combining multileaf...accelerator, Phys. Med. Biol., 45:2321-41 (1999) 25 . C.-M. Ma, T. Pawlicki, S.B. Jiang, E.Mok, A. Kapur, L. Xing, L. Ma and A.L. Boyer, Verification of IMRT...and measured by ion chamber for a 12 MeV electron beam from a Varian Clinac 2300CD accelerator. The agreement was within I% for both cases. 25 500

  9. High Energy Laboratory Astrophysics using an X-Ray Microcalorimeter with an Electron Beam Ion Trap

    NASA Astrophysics Data System (ADS)

    Porter, Frederick

    Since the summer of 2000 we have successfully deployed a high-resolution x-ray microcalorimeter spectrometer, based on the spaceflight XRS instrument, at the Electron Beam Ion Trap (EBIT) facility at the Lawrence Livermore National Laboratory. Over the last 15 years, this highly successful partnership has made fundamental measurements in laboratory astrophysics including the measurements of the absolute cross sections of all the Fe L shell transitions from Fe XVII to Fe XXIV, line ratios in Fe and Ni L shell transitions, measurements of Fe K shell emission over a wide range of electron energies, and direct measurements of charge exchange emission from highly ionized Fe, O, N, and most recently L shell S, using a variety of donor gases. This work has resulted in the publication of over 40 peer-reviewed articles with many more either submitted or in preparation. The newest addition to the facility, the ECS microcalorimeter spectrometer, developed under this program, has performed flawlessly as a facility-class instrument since 2007. We propose here to continue our highly successful partnership and deploy new technology to resolve lines in the important ¼ keV band that encompasses the M-shell iron emission and the L shell emission, including charge exchange, of many of the lowerZ elements, such as Si, S, Mg, Ne, Ca, and Ar. We thus propose completing a new spectrometer that will bring substantially improved performance to the laboratory astrophysics program at EBIT and will enable fundamentally new measurements. Thus, in addition to maintaining the current spectrometers, which will begin this work, a significant component of this proposal is the completion of a new spectrometer leveraged off of the substantial progress in high-resolution x-ray detectors developed for the IXO and now Athena large-scale observatories. The spectrometer will be composed of a detector system with unparalleled spectral resolution: 2 eV resolution across the 0.05-10 keV band. This will

  10. Beam-energy inequality in the beam-beam interaction

    SciTech Connect

    Krishnagopal, S.; Siemann, R. )

    1990-03-01

    Conditions for energy transparency,'' unequal-energy beams having the same beam-beam behavior, are derived for round beams from a Hamiltonian model of the beam-beam interaction. These conditions are equal fractional betatron tunes, equal synchrotron tunes, equal beam-beam strength parameters, equal nominal sizes, equal {beta}{sup *}'s and equal bunch lengths. With these conditions the only way to compensate for unequal energies is with the number of particles per bunch.

  11. Beam stability investigation for a free electron lithographic laser based on an energy-recovery linac

    NASA Astrophysics Data System (ADS)

    Getmanov, Ya. V.; Vinokurov, N. A.; Shevchenko, O. A.; Davidyuk, I. V.

    2016-12-01

    According to leading producers of microelectronic devices, lithography based on free electron lasers (FEL) could become the main technology for the mass production of elements with a scale up to 5 nm in the near future. One of the main hindrances in this path is the absence of working FEL with the required parameters. A feasibility study devoted to the production of such an FEL based on a superconducting energyrecovery linac (ERL) has been carried out at the Budker Institute of Nuclear Physics (BINP). The ERL average current is limited by longitudinal and transverse instabilities, caused by the interaction of an electron beam with the fields induced by it in the superconducting cavities. The estimations of the threshold currents and parameters of the ERL required for the operation of FEL are obtained.

  12. Improved dose homogeneity in scalp irradiation using a single set-up point and different energy electron beams.

    PubMed

    Yaparpalvi, R; Fontenla, D P; Beitler, J J

    2002-08-01

    Homogeneous irradiation of the entire or a large portion of the superficial scalp poses both technical and dosimetric challenges. Some techniques will irradiate too much of the underlying normal brain while other techniques are either complex and involve field matching problems or may require sophisticated linear accelerator (linac) add-ons such as intensity modulated radiation therapy (IMRT)/electron multileaf collimation. However, many radiotherapy facilities are not equipped with such treatment modalities. We propose a practical treatment technique that can be delivered with a standard linac capable of producing high energy electrons. The proposed technique offers a simple alternative for achieving results equivalent to IMRT. Dose homogeneity throughout the treatment volume is achieved by aiming different energy electron beams at differential areas of the treatment surface to achieve improved dosimetry and rapid treatment delivery, while using a single set-up point. We introduced this treatment technique at our institution to treat superficial cancers of the scalp and other irregular surfaces.

  13. Sci—Thur PM: Planning and Delivery — 02: Treatment planning workflow for very high-energy electron beam radiotherapy

    SciTech Connect

    Bazalova, Magdalena; Qu, Bradley; Palma, Bianey; Maxim, Peter; Loo, Billy; Hårdemark, Bjorn; Hynning, Elin

    2014-08-15

    Purpose: To develop treatment planning workflow for rapid radiotherapy delivered with very-high energy electron (VHEE) scanning beam. Methods: VHEE radiotherapy treatment planning was performed by linking Monte Carlo (MC) dose calculations with inverse optimization in a research version of RayStation. In order to study a number of treatment parameters, a Matlab graphical user interface (GUI) for calculation of VHEE beamlet dose was developed. Through the GUI, EGSnrc MC simulations were run for a number of beam energies, number of beams, beamlet spot and grid sizes, and machine bore sizes. VHEE plans for a pediatric patient with a 4.3 cm{sup 3} brain target optimized with spot-scanning algorithm in RayStation were compared to the clinically delivered 6 MV VMAT plan. Results and Discussion: VHEE beam energy had the largest effect on the quality of dose distributions. For the same target dose, the mean doses to critical organs decreased by 10–15% when planned with 100 MeV compared to 60 MeV. VHEE plans calculated with 36 beams outperformed plans calculated with 13 and 17 beams. While beamlet spacing and bore size had a small effect on VHEE dose distributions, 0.1-3mm beamlet sizes resulted in identical dose distributions. Critical organ doses were by up to 70% lower in the best VHEE plan compared to the clinical 6 MV VMAT plan. Conclusions: We have developed a GUI for MC beamlet generation for treatment planning of VHEE radiotherapy. We have demonstrated that pediatric VHEE plans resulted in significant critical organ dose sparing compared to the clinical VMAT plan.

  14. 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.

  15. 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.

  16. Electron beam emittance monitor for the SSC

    SciTech Connect

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

    1993-05-01

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

  17. Measurement and simulation of the impact of coherent synchrotron radiation on the Jefferson Laboratory energy recovery linac electron beam

    DOE PAGES

    Hall, C C.; Biedron, S G.; Edelen, A L.; ...

    2015-03-09

    In an experiment conducted on the Jefferson Laboratory IR free-electron laser driver, the effects of coherent synchrotron radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR recirculator. Here we examine the impact of CSR on the average energy loss as a function of bunch compression as well as the impact of CSR on the energy spectrum of the bunch. Simulation of beam dynamics in the machine, including the one-dimensional CSR model, shows very good agreement with themore » measured effect of CSR on the average energy loss as a function of compression. Finally, a well-defined structure is observed in the energy spectrum with a feature in the spectrum that varies as a function of the compression. This effect is examined in simulations, as well, and a simple explanation for the variation is proposed.« less

  18. Single-stage plasma-based correlated energy spread compensation for ultrahigh 6D brightness electron beams

    DOE PAGES

    Manahan, Grace G.; Habib, A. F.; Scherkl, P.; ...

    2017-06-05

    Plasma photocathode wakefield acceleration combines energy gains of tens of GeV m–1 with generation of ultralow emittance electron bunches, and opens a path towards 5D-brightness orders of magnitude larger than state-of-the-art. This holds great promise for compact accelerator building blocks and advanced light sources. However, an intrinsic by-product of the enormous electric field gradients inherent to plasma accelerators is substantial correlated energy spread—an obstacle for key applications such as free-electron-lasers. Here we show that by releasing an additional tailored escort electron beam at a later phase of the acceleration, when the witness bunch is relativistically stable, the plasma wave canmore » be locally overloaded without compromising the witness bunch normalized emittance. Here, this reverses the effective accelerating gradient, and counter-rotates the accumulated negative longitudinal phase space chirp of the witness bunch. Thereby, the energy spread is reduced by an order of magnitude, thus enabling the production of ultrahigh 6D-brightness beams.« less

  19. Single-stage plasma-based correlated energy spread compensation for ultrahigh 6D brightness electron beams

    PubMed Central

    Manahan, G. G.; Habib, A. F.; Scherkl, P.; Delinikolas, P.; Beaton, A.; Knetsch, A.; Karger, O.; Wittig, G.; Heinemann, T.; Sheng, Z. M.; Cary, J. R.; Bruhwiler, D. L.; Rosenzweig, J. B.; Hidding, B.

    2017-01-01

    Plasma photocathode wakefield acceleration combines energy gains of tens of GeV m−1 with generation of ultralow emittance electron bunches, and opens a path towards 5D-brightness orders of magnitude larger than state-of-the-art. This holds great promise for compact accelerator building blocks and advanced light sources. However, an intrinsic by-product of the enormous electric field gradients inherent to plasma accelerators is substantial correlated energy spread—an obstacle for key applications such as free-electron-lasers. Here we show that by releasing an additional tailored escort electron beam at a later phase of the acceleration, when the witness bunch is relativistically stable, the plasma wave can be locally overloaded without compromising the witness bunch normalized emittance. This reverses the effective accelerating gradient, and counter-rotates the accumulated negative longitudinal phase space chirp of the witness bunch. Thereby, the energy spread is reduced by an order of magnitude, thus enabling the production of ultrahigh 6D-brightness beams. PMID:28580954

  20. Energy dependence and dose response of Gafchromic EBT2 film over a wide range of photon, electron, and proton beam energies

    SciTech Connect

    Arjomandy, Bijan; Tailor, Ramesh; Anand, Aman; Sahoo, Narayan; Gillin, Michael; Prado, Karl; Vicic, Milos

    2010-05-15

    Purpose: Since the Gafchromic film EBT has been recently replaced by the newer model EBT2, its characterization, especially energy dependence, has become critically important. The energy dependence of the dose response of Gafchromic EBT2 film is evaluated for a broad range of energies from different radiation sources used in radiation therapy. Methods: The beams used for this study comprised of kilovoltage x rays (75, 125, and 250 kVp), {sup 137}Cs gamma (662 KeV), {sup 60}Co gamma (1.17-1.33 MeV), megavoltage x rays (6 and 18 MV), electron beams (6 and 20 MeV), and proton beams (100 and 250 MeV). The film's response to each of the above energies was measured over the dose range of 0.4-10 Gy, which corresponds to optical densities ranging from 0.05 to 0.74 for the film reader used. Results: The energy dependence of EBT2 was found to be relatively small within measurement uncertainties (1{sigma}={+-}4.5%) for all energies and modalities. Conclusion: For relative and absolute dosimetry of radiation therapy beams, the weak energy dependence of the EBT2 makes it most suitable for clinical use compared to other films.

  1. Energy Loss of a High Charge Bunched Electron Beam in Plasma: Nonlinear Plasma Response and Linear Scaling

    NASA Astrophysics Data System (ADS)

    Rosenzweig, J. B.; Barov, N.; Thompson, M. C.; Yoder, R.

    2002-12-01

    There has been much experimental and theoretical interest in blowout regime of plasma wakefield acceleration (PWFA), which features ultra-high accelerating fields, linear transverse focusing forces, and nonlinear plasma motion. Using an exact analysis, we examine here a fundamental limit of nonlinear PWFA excitation, by an infinitesimally short, relativistic electron beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity, and relativistic plasma effects become important or dominant. The physical bases for this persistence of linear response are pointed out. As a byproduct of our analysis, we re-examine the issue of field divergence as the point-charge limit is approached, suggesting an important modification of commonly held views of evading unphysical energy loss. Deviations from linear behavior are investigated using simulations with finite length beams. The peak accelerating field in the plasma wave excited behind a finite-length beam is also examined, with the artifact of wave spiking adding to the apparent persistence of linear scaling of the peak field amplitude well into the nonlinear regime. On the other hand, at large enough normalized charge, linear scaling of fields collapses, with serious consequences for plasma wave excitation efficiency. The dramatic implications of these results for observing the collapse of linear scaling in planned experiments are discussed.

  2. Measuring electron beam polarization

    NASA Astrophysics Data System (ADS)

    Napolitano, J.

    1992-12-01

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

  3. Estimation of the electron beam energy spread for TEM information limit

    SciTech Connect

    O'Keefe, Michael A.; Tiemeijer, Peter C.; Sidorov, Maxim V.

    2002-02-20

    Sub-Angstrom TEM of materials requires focal-series reconstruction (FSR) or electron holography to retrieve the electron wave at the specimen exit-surface to very high resolution. As a consequence, we need to measure the microscope information limit. With a sub-Angstrom information limit, the one-Angstrom microscope (OAM) project at the NCEM has achieved sub-Angstrom resolution by FSR. We present a new method of estimating the information limit of the microscope, based on energy-spread measurements with an image filter.

  4. 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.

  5. Electra: A Repetitively Pulsed, Electron Beam Pumped KrF Laser to Develop the Technologies for Fusion Energy

    DTIC Science & Technology

    2005-06-01

    primary source of beam electrons comes from the inside of the capillary wall, and not explosive emission from the cathode material itself. This should...emitted from a field emission cathode driven by a fast pulsed power system. The electron beam propagates through a thin foil, which serves as the...pressure after the shot was reduced about five fold. In the case of the carbon fiber cathode , the RMS non-uniformity of the electron beam dropped

  6. 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.

  7. Transport of low- and medium-energy electron and ion beams in seawater and its vapors

    NASA Technical Reports Server (NTRS)

    Erwin, Daniel A.; Kunc, Joseph A.

    1988-01-01

    A general theory of stopping power for electrons and ions in a target medium (gas, liquid, or thin solid foil) containing neutral as well as positive and negative ions is developed. The approach is quite accurate in the low- and medium-energy range (less than 1 MeV), where the Bethe stopping-power cross section is inaccurate. The energy transfer during individual collisions is treated by the binary-encounter approximation. The theory is applied to determine the stopping power of seawater, whose major components are H2O molecules and Na(+) and Cl(-) ions. The stopping-power cross sections for low- and medium-energy protons in water show excellent agreement with existing measurements.

  8. 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.

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

    PubMed

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

    2012-09-01

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

  10. Evolution of Texture from a Single Crystal Ti-6Al-4V Substrate During Electron Beam Directed Energy Deposition

    NASA Astrophysics Data System (ADS)

    Butler, Todd M.; Brice, Craig A.; Tayon, Wesley A.; Semiatin, S. Lee; Pilchak, Adam L.

    2017-07-01

    Additive manufacturing of Ti-6Al-4V commonly produces <001> β -fiber textures aligned with the build direction. We have performed wire-feed electron beam directed energy deposition on the {112} β plane of a single prior β-grain. The build initially grew epitaxially from the substrate with the preferred <001> growth direction significantly angled away from the build direction. However, continued layer deposition drove the formation of a <001> β -fiber texture aligned with the build direction and the direction of the strongest thermal gradient.

  11. Evolution of Texture from a Single Crystal Ti-6Al-4V Substrate During Electron Beam Directed Energy Deposition

    NASA Astrophysics Data System (ADS)

    Butler, Todd M.; Brice, Craig A.; Tayon, Wesley A.; Semiatin, S. Lee; Pilchak, Adam L.

    2017-10-01

    Additive manufacturing of Ti-6Al-4V commonly produces 〈001〉 β -fiber textures aligned with the build direction. We have performed wire-feed electron beam directed energy deposition on the {112} β plane of a single prior β-grain. The build initially grew epitaxially from the substrate with the preferred 〈001〉 growth direction significantly angled away from the build direction. However, continued layer deposition drove the formation of a 〈001〉 β -fiber texture aligned with the build direction and the direction of the strongest thermal gradient.

  12. On the phase shift of reflection high energy electron diffraction intensity oscillations during Ge(001) homoepitaxy by molecular beam epitaxy

    SciTech Connect

    Shin Byungha; Leonard, John P.; McCamy, James W.; Aziz, Michael J.

    2007-03-15

    The authors have conducted a systematic investigation of the phase shift of the reflection high energy electron diffraction (RHEED) intensity oscillations during homoepitaxy of Ge(001) by molecular beam epitaxy for a wide range of diffraction conditions. Their results show that for small incidence angles with a beam azimuth several degrees away from the <110> crystallographic symmetry direction, the phase is independent of incidence angle; however, it starts to shift once the incidence angle is high enough that the (004) Kikuchi line appears in the RHEED pattern. Moreover, under some conditions they observe the oscillations from only the Kikuchi feature and not from the specular spot, and the oscillatory behavior of the Kikuchi feature is almost out of phase with that of the specular spot. They conclude that the phase shift is caused by the overlap of the specular spot and the Kikuchi features, in contrast to models involving dynamical scattering theory for the phase shift. They discuss necessary conditions for avoiding interference.

  13. 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.

  14. Space Charge Correction on Emittance Measurement of Low Energy Electron Beams

    SciTech Connect

    Treado, Colleen J.; /Massachusetts U., Amherst

    2012-09-07

    The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.

  15. On problems of reducing energy consumption for irradiation of flue gas in the electron beam gas treatment technology

    NASA Astrophysics Data System (ADS)

    Fainchtein, O. L.; Sagaidak, M. V.; Morgunov, V. V.

    2002-11-01

    The electron beam (EB) flue gas treatment technology is presented as a combination of radiation chemical transformations and phase transitions. Some theoretical and experimental evidence is presented which suggests that there are two mechanisms to substantially reduce the energy consumption for gas irradiation: droplet mechanism and a mechanism related to specific EB current density (current-mechanism). Both the mechanisms are based on chain reactions of oxidation. The 100,000 m 3/h Slavyanskaya Electron Beam Industrial Plant (developed by our Institute "Energostal", being built in Ukraine) is described. The plant design is aimed at solving the two main problems of the EB scrubbing technology: reduction of energy consumption for irradiation (using a droplet mechanism) and more reliable collection of salt particles (using wet particles collectors). The paper is devoted to EB flue gas treatment technology to remove SO 2 and NO x from flue gas, its present status and the prospects of its further development and optimization, special attention being paid to reduction of energy consumption.

  16. Numerical simulation and optimization of the variable energy 60-1000 MeV proton beams at PNPI synchrocyclotron for testing the radiation resistance of electronics

    NASA Astrophysics Data System (ADS)

    Artamonov, S. A.; Ivanov, E. M.; Ivanov, N. A.; Lebedeva, J. S.; Riabov, G. A.

    2017-01-01

    A universal center for testing electronic components (ECs) for the needs of aviation and space is created in the SC-1000 Petersburg Nuclear Physics Institute, National Research Centre "Kurchatov Institute" (PNPI NRC KI). One of the main instruments of these tests is variable energy protons beams. This paper presents Monte Carlo simulation results for a proton beam with energy of 1000 MeV passing through copper and tungsten degraders, and defines the length of these degraders to obtain energies of 60, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 MeV. Detailed studies of further transmission of the proton beams along the beam line using the copper degrader are accomplished. Basic theoretical parameters for each proton beam, such as the intensity, the energy heterogeneity, beam size, and uniformity of its spatial distribution are obtained.

  17. MO-H-19A-01: FEATURED PRESENTATION - Treatment Planning Tool for Radiotherapy with Very High-Energy Electron Beams

    SciTech Connect

    Bazalova, M; Qu, B; Palma, B; Loo, B; Maxim, P; Hynning, E; Hardemark, B

    2014-06-15

    Purpose: To develop a tool for treatment planning optimization for fast radiotherapy delivered with very high-energy electron beams (VHEE) and to compare VHEE plans to state-of-the-art plans for challenging pelvis and H'N cases. Methods: Treatment planning for radiotherapy delivered with VHEE scanning pencil beams was performed by integrating EGSnrc Monte Carlo (MC) dose calculations with spot scanning optimization run in a research version of RayStation. A Matlab GUI for MC beamlet generation was developed, in which treatment parameters such as the pencil beam size and spacing, energy and number of beams can be selected. Treatment planning study for H'N and pelvis cases was performed and the effect of treatment parameters on the delivered dose distributions was evaluated and compared to the clinical treatment plans. The pelvis case with a 691cm3 PTV was treated with 2-arc 15MV VMAT and the H'N case with four PTVs with total volume of 531cm3 was treated with 4-arc 6MV VMAT. Results: Most studied VHEE plans outperformed VMAT plans. The best pelvis 80MeV VHEE plan with 25 beams resulted in 12% body dose sparing and 8% sparing to the bowel and right femur compared to the VMAT plan. The 100MeV plan was superior to the 150MeV plan. Mixing 100 and 150MeV improved dose sparing to the bladder by 7% compared to either plan. Plans with 16 and 36 beams did not significantly affect the dose distributions compared to 25 beam plans. The best H'N 100MeV VHEE plan decreased mean doses to the brainstem, chiasm, and both globes by 10-42% compared to the VMAT plan. Conclusion: The pelvis and H'N cases suggested that sixteen 100MeV beams might be sufficient specifications of a novel VHEE treatment machine. However, optimum machine parameters will be determined with the presented VHEE treatment-planning tool for a large number of clinical cases. BW Loo and P Maxim received research support from RaySearch Laboratories. E Hynning and B Hardemark are employees of RaySearch Laboratories.

  18. Ultrafast harmonic rf kicker design and beam dynamics analysis for an energy recovery linac based electron circulator cooler ring

    DOE PAGES

    Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.; ...

    2016-08-01

    An ultrafast kicker system is being developed for the energy recovery linac (ERL) based electron circulator cooler ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously named MEIC). In the CCR, the injected electron bunches can be recirculated while performing ion cooling for 10–30 turns before the extraction, thus reducing the recirculation beam current in the ERL to 1/10–1/30 (150mA–50 mA) of the cooling beam current (up to 1.5 A). Assuming a bunch repetition rate of 476.3 MHz and a recirculating factor of 10 in the CCR, the kicker is required to operate at a pulse repetitionmore » rate of 47.63 MHz with pulse width of around 2 ns, so that only every 10th bunch in the CCR will experience a transverse kick while the rest of the bunches will not be disturbed. Such a kicker pulse can be synthesized by ten harmonic modes of the 47.63 MHz kicker pulse repetition frequency, using up to four quarter wavelength resonator (QWR) based deflecting cavities. In this paper, several methods to synthesize such a kicker waveform will be discussed and a comparison of their beam dynamics performance is made using ELEGANT. Four QWR cavities are envisaged with high transverse shunt impedance requiring less than 100 W of total rf power for a Flat-Top kick pulse. Multipole fields due to the asymmetry of this type of cavity are analyzed. The transverse emittance growth due to the sextupole component is simulated in ELEGANT. In conclusion, off-axis injection and extraction issues and beam optics using a multicavity kick-drift scheme will also be discussed.« less

  19. Time-domain measurement of a self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering

    SciTech Connect

    Marcus, G.; Rosenzweig, J. B.; Artioli, M.; Ciocci, F.; Del Franco, M.; Giannessi, L.; Petralia, A.; Quattromini, M.; Bacci, A.; Bellaveglia, M.; Chiadroni, E.; Di Pirro, G.; Ferrario, M.; Filippetto, D.; Gatti, G.; Rossi, A. R.; Cianchi, A.; Labat, M.; Mostacci, A.; Petrillo, V.; and others

    2012-09-24

    We report, with an unequivocal time-domain measurement, that an appropriately chosen undulator taper can compensate for an electron beam longitudinal energy-chirp in a free-electron laser amplifier, leading to the generation of single-spike radiation close to the Fourier limit. The measurements were taken using the frequency-resolved optical gating technique by employing an advanced transient-grating diagnostic geometry. The reconstructed longitudinal radiation characteristics are compared in detail to prediction from time-dependent three-dimensional simulations.

  20. Demonstration of a narrow energy spread, ∼0.5  GeV electron beam from a two-stage laser wakefield accelerator.

    PubMed

    Pollock, B B; Clayton, C E; Ralph, J E; Albert, F; Davidson, A; Divol, L; Filip, C; Glenzer, S H; Herpoldt, K; Lu, W; Marsh, K A; Meinecke, J; Mori, W B; Pak, A; Rensink, T C; Ross, J S; Shaw, J; Tynan, G R; Joshi, C; Froula, D H

    2011-07-22

    Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages of GeV scale, high-quality electron beams for applications such as x-ray free electron lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens of vacuum diffraction lengths, to give >1  GeV energy in centimeter-scale low density plasmas using ionization-induced injection to inject charge into the wake even at low densities. By restricting electron injection to a distinct short region, the injector stage, energetic electron beams (of the order of 100 MeV) with a relatively large energy spread are generated. Some of these electrons are then further accelerated by a second, longer accelerator stage, which increases their energy to ∼0.5  GeV while reducing the relative energy spread to <5% FWHM.

  1. 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.

  2. Optimization of laser parameters to obtain high-energy, high-quality electron beams through laser-plasma acceleration

    SciTech Connect

    Samant, Sushil Arun; Sarkar, Deepangkar; Krishnagopal, Srinivas; Upadhyay, Ajay K.; Jha, Pallavi

    2010-10-15

    The propagation of an intense (a{sub 0}=3), short-pulse (L{approx}{lambda}{sub p}) laser through a homogeneous plasma has been investigated. Using two-dimensional simulations for a{sub 0}=3, the pulse-length and spot-size at three different plasma densities were optimized in order to get a better quality beam in laser wakefield accelerator. The study reveals that with increasing pulse-length the acceleration increases, but after a certain pulse-length (L>0.23{lambda}{sub p}) the emittance blows-up unacceptably. For spot-sizes less than that given by k{sub p0}r{sub s}=2{radical}(a{sub 0}), trapping is poor or nonexistent, and the optimal spot-size is larger. The deviation of the optimal spot-size from this formula increases as the density decreases. The efficacy of these two-dimensional simulations has been validated by running three-dimensional simulations at the highest density. It has been shown that good quality GeV-class beams can be obtained at plasma densities of {approx}10{sup 18} cm{sup -3}. The quality of the beam can be substantially improved by selecting only the high-energy peak; in this fashion an energy-spread of better than 1% and a current in tens of kA can be achieved, which are important for applications such as free-electron lasers.

  3. Electron density profile measurements at a self-focusing ion beam with high current density and low energy extracted through concave electrodes

    SciTech Connect

    Fujiwara, Y. Nakamiya, A.; Sakakita, H.; Hirano, Y.; Kiyama, S.; Koguchi, H.

    2014-02-15

    The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are ∼0.9 eV and ∼8 × 10{sup 8} cm{sup −3} at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.

  4. Treatment planning for radiotherapy with very high-energy electron beams and comparison of VHEE and VMAT plans.

    PubMed

    Bazalova-Carter, Magdalena; Qu, Bradley; Palma, Bianey; Hårdemark, Björn; Hynning, Elin; Jensen, Christopher; Maxim, Peter G; Loo, Billy W

    2015-05-01

    The aim of this work was to develop a treatment planning workflow for rapid radiotherapy delivered with very high-energy electron (VHEE) scanning pencil beams of 60-120 MeV and to study VHEE plans as a function of VHEE treatment parameters. Additionally, VHEE plans were compared to clinical state-of-the-art volumetric modulated arc therapy (VMAT) photon plans for three cases. VHEE radiotherapy treatment planning was performed by linking EGSnrc Monte Carlo (MC) dose calculations with inverse treatment planning in a research version of RayStation. In order to study the effect of VHEE treatment parameters on VHEE dose distributions, a matlab graphical user interface (GUI) for calculation of VHEE MC pencil beam doses was developed. Through the GUI, pediatric case MC simulations were run for a number of beam energies (60, 80, 100, and 120 MeV), number of beams (13, 17, and 36), pencil beam spot (0.1, 1.0, and 3.0 mm) and grid (2.0, 2.5, and 3.5 mm) sizes, and source-to-axis distance, SAD (40 and 50 cm). VHEE plans for the pediatric case calculated with the different treatment parameters were optimized and compared. Furthermore, 100 MeV VHEE plans for the pediatric case, a lung, and a prostate case were calculated and compared to the clinically delivered VMAT plans. All plans were normalized such that the 100% isodose line covered 95% of the target volume. VHEE beam energy had the largest effect on the quality of dose distributions of the pediatric case. For the same target dose, the mean doses to organs at risk (OARs) decreased by 5%-16% when planned with 100 MeV compared to 60 MeV, but there was no further improvement in the 120 MeV plan. VHEE plans calculated with 36 beams outperformed plans calculated with 13 and 17 beams, but to a more modest degree (<8%). While pencil beam spacing and SAD had a small effect on VHEE dose distributions, 0.1-3 mm pencil beam sizes resulted in identical dose distributions. For the 100 MeV VHEE pediatric plan, OAR doses were up to 70

  5. Treatment planning for radiotherapy with very high-energy electron beams and comparison of VHEE and VMAT plans

    SciTech Connect

    Bazalova-Carter, Magdalena; Qu, Bradley; Palma, Bianey; Jensen, Christopher; Maxim, Peter G. E-mail: BWLoo@Stanford.edu; Loo, Billy W. E-mail: BWLoo@Stanford.edu; Hårdemark, Björn; Hynning, Elin

    2015-05-15

    Purpose: The aim of this work was to develop a treatment planning workflow for rapid radiotherapy delivered with very high-energy electron (VHEE) scanning pencil beams of 60–120 MeV and to study VHEE plans as a function of VHEE treatment parameters. Additionally, VHEE plans were compared to clinical state-of-the-art volumetric modulated arc therapy (VMAT) photon plans for three cases. Methods: VHEE radiotherapy treatment planning was performed by linking EGSnrc Monte Carlo (MC) dose calculations with inverse treatment planning in a research version of RayStation. In order to study the effect of VHEE treatment parameters on VHEE dose distributions, a MATLAB graphical user interface (GUI) for calculation of VHEE MC pencil beam doses was developed. Through the GUI, pediatric case MC simulations were run for a number of beam energies (60, 80, 100, and 120 MeV), number of beams (13, 17, and 36), pencil beam spot (0.1, 1.0, and 3.0 mm) and grid (2.0, 2.5, and 3.5 mm) sizes, and source-to-axis distance, SAD (40 and 50 cm). VHEE plans for the pediatric case calculated with the different treatment parameters were optimized and compared. Furthermore, 100 MeV VHEE plans for the pediatric case, a lung, and a prostate case were calculated and compared to the clinically delivered VMAT plans. All plans were normalized such that the 100% isodose line covered 95% of the target volume. Results: VHEE beam energy had the largest effect on the quality of dose distributions of the pediatric case. For the same target dose, the mean doses to organs at risk (OARs) decreased by 5%–16% when planned with 100 MeV compared to 60 MeV, but there was no further improvement in the 120 MeV plan. VHEE plans calculated with 36 beams outperformed plans calculated with 13 and 17 beams, but to a more modest degree (<8%). While pencil beam spacing and SAD had a small effect on VHEE dose distributions, 0.1–3 mm pencil beam sizes resulted in identical dose distributions. For the 100 MeV VHEE pediatric

  6. The effect of high-energy electron-beam irradiation on microstructural modification of a high-speed steel roll

    NASA Astrophysics Data System (ADS)

    Suh, Dongwoo; Lee, Sunghak; Koo, Yangmo; Lee, Hui Choon

    1996-10-01

    The purpose of this study is to investigate the microstructural modification in a high-speed steel (HSS) roll irradiated with an accelerated high-energy electron beam. The HSS roll samples were irradiated at the beam travel speeds of 2.5 to 25 mm/s using an electron accelerator (1.4 MeV). The microstructure was examined with a scanning electron microscope (SEM) capable of in situ fracture testing and simultaneous measurement of the apparent fracture toughness. Irradiation changed the matrix phase from tempered martensite to a mixture of retained austenite and martensite. Coarse primary carbides were partially or completely dissolved, depending on the heat input. Irradiation greatly improved the fracture properties because of the presence of retained austenite, which could retard crack propagation, although hardness was decreased. Occasional interior quench cracks were found in the heat-affected region. Appropriate processing methods, such as pre- or postirradiation, were suggested. A heat transfer analysis of the irradiated surface layer was also carried out to elucidate the influence of the irradiation parameters on the microstructure.

  7. Compensating the electron beam energy spread by the natural transverse gradient of laser undulator in all-optical x-ray light sources.

    PubMed

    Zhang, Tong; Feng, Chao; Deng, Haixiao; Wang, Dong; Dai, Zhimin; Zhao, Zhentang

    2014-06-02

    All-optical ideas provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this paper, the beam energy spread effect is proposed to be significantly compensated by the natural transverse gradient of a laser undulator when properly transverse-dispersing the electron beam. Theoretical analysis and numerical simulations on conventional laser-Compton scattering sources and high-gain all-optical x-ray free-electron lasers with the electron beams from laser-plasma accelerators are presented.

  8. Electron beam control for barely separated beams

    DOEpatents

    Douglas, David R.; Ament, Lucas J. P.

    2017-04-18

    A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

  9. Compact disposal of high-energy electron beams using passive or laser-driven plasma decelerating stage

    SciTech Connect

    Bonatto, A.; Schroeder, C. B.; Vay, J. -L.; Geddes, C. R.; Benedetti, C.; Esarey and, E.; Leemans, W. P.

    2014-07-13

    A plasma decelerating stage is investigated as a compact alternative for the disposal of high-energy beams (beam dumps). This could benefit the design of laser-driven plasma accelerator (LPA) applications that require transportability and or high-repetition-rate operation regimes. Passive and laser-driven (active) plasma-based beam dumps are studied analytically and with particle-in-cell (PIC) simulations in a 1D geometry. Analytical estimates for the beam energy loss are compared to and extended by the PIC simulations, showing that with the proposed schemes a beam can be efficiently decelerated in a centimeter-scale distance.

  10. Compact disposal of high-energy electron beams using passive or laser-driven plasma decelerating stage

    SciTech Connect

    Bonatto, A.; Schroeder, C. B.; Vay, J. -L.; Geddes, C. R.; Benedetti, C.; Esarey and, E.; Leemans, W. P.

    2014-07-13

    A plasma decelerating stage is investigated as a compact alternative for the disposal of high-energy beams (beam dumps). This could benefit the design of laser-driven plasma accelerator (LPA) applications that require transportability and or high-repetition-rate operation regimes. Passive and laser-driven (active) plasma-based beam dumps are studied analytically and with particle-in-cell (PIC) simulations in a 1D geometry. Analytical estimates for the beam energy loss are compared to and extended by the PIC simulations, showing that with the proposed schemes a beam can be efficiently decelerated in a centimeter-scale distance.

  11. Assessing electron beam sensitivity for SrTiO3 and La0.7Sr0.3MnO3 using electron energy loss spectroscopy.

    PubMed

    Nord, Magnus; Vullum, Per Erik; Hallsteinsen, Ingrid; Tybell, Thomas; Holmestad, Randi

    2016-10-01

    Thresholds for beam damage have been assessed for La0.7Sr0.3MnO3 and SrTiO3 as a function of electron probe current and exposure time at 80 and 200kV acceleration voltage. The materials were exposed to an intense electron probe by aberration corrected scanning transmission electron microscopy (STEM) with simultaneous acquisition of electron energy loss spectroscopy (EELS) data. Electron beam damage was identified by changes of the core loss fine structure after quantification by a refined and improved model based approach. At 200kV acceleration voltage, damage in SrTiO3 was identified by changes both in the EEL fine structure and by contrast changes in the STEM images. However, the changes in the STEM image contrast as introduced by minor damage can be difficult to detect under several common experimental conditions. No damage was observed in SrTiO3 at 80kV acceleration voltage, independent of probe current and exposure time. In La0.7Sr0.3MnO3, beam damage was observed at both 80 and 200kV acceleration voltages. This damage was observed by large changes in the EEL fine structure, but not by any detectable changes in the STEM images. The typical method to validate if damage has been introduced during acquisitions is to compare STEM images prior to and after spectroscopy. Quantifications in this work show that this method possibly can result in misinterpretation of beam damage as changes of material properties.

  12. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  13. Beam distribution reconstruction simulation for electron beam probe

    NASA Astrophysics Data System (ADS)

    Feng, Yong-Chun; Mao, Rui-Shi; Li, Peng; Kang, Xin-Cai; Yin, Yan; Liu, Tong; You, Yao-Yao; Chen, Yu-Cong; Zhao, Tie-Cheng; Xu, Zhi-Guo; Wang, Yan-Yu; Yuan, You-Jin

    2017-07-01

    An electron beam probe (EBP) is a detector which makes use of a low-intensity and low-energy electron beam to measure the transverse profile, bunch shape, beam neutralization and beam wake field of an intense beam with small dimensions. While it can be applied to many aspects, we limit our analysis to beam distribution reconstruction. This kind of detector is almost non-interceptive for all of the beam and does not disturb the machine environment. In this paper, we present the theoretical aspects behind this technique for beam distribution measurement and some simulation results of the detector involved. First, a method to obtain a parallel electron beam is introduced and a simulation code is developed. An EBP as a profile monitor for dense beams is then simulated using the fast scan method for various target beam profiles, including KV distribution, waterbag distribution, parabolic distribution, Gaussian distribution and halo distribution. Profile reconstruction from the deflected electron beam trajectory is implemented and compared with the actual profile, and the expected agreement is achieved. Furthermore, as well as fast scan, a slow scan, i.e. step-by-step scan, is considered, which lowers the requirement for hardware, i.e. Radio Frequency deflector. We calculate the three-dimensional electric field of a Gaussian distribution and simulate the electron motion in this field. In addition, a fast scan along the target beam direction and slow scan across the beam are also presented, and can provide a measurement of longitudinal distribution as well as transverse profile simultaneously. As an example, simulation results for the China Accelerator Driven Sub-critical System (CADS) and High Intensity Heavy Ion Accelerator Facility (HIAF) are given. Finally, a potential system design for an EBP is described.

  14. SU‐C‐105‐05: Reference Dosimetry of High‐Energy Electron Beams with a Farmer‐Type Ionization Chamber

    SciTech Connect

    Muir, B; Rogers, D

    2013-06-15

    Purpose: To investigate gradient effects and provide Monte Carlo calculated beam quality conversion factors to characterize the Farmer‐type NE2571 ion chamber for high‐energy reference dosimetry of clinical electron beams. Methods: The EGSnrc code system is used to calculate the absorbed dose to water and to the gas in a fully modeled NE2571 chamber as a function of depth in a water phantom. Electron beams incident on the surface of the phantom are modeled using realistic BEAMnrc accelerator simulations and electron beam spectra. Beam quality conversion factors are determined using calculated doses to water and to air in the chamber in high‐energy electron beams and in a cobalt‐60 reference field. Calculated water‐to‐air stopping power ratios are employed for investigation of the overall ion chamber perturbation factor. Results: An upstream shift of 0.3–0.4 multiplied by the chamber radius, r-cav, both minimizes the variation of the overall ion chamber perturbation factor with depth and reduces the difference between the beam quality specifier (R{sub 5} {sub 0}) calculated using ion chamber simulations and that obtained with simulations of dose‐to‐water in the phantom. Beam quality conversion factors are obtained at the reference depth and gradient effects are optimized using a shift of 0.2r-cav. The photon‐electron conversion factor, k-ecal, amounts to 0.906 when gradient effects are minimized using the shift established here and 0.903 if no shift of the data is used. Systematic uncertainties in beam quality conversion factors are investigated and amount to between 0.4 to 1.1% depending on assumptions used. Conclusion: The calculations obtained in this work characterize the use of an NE2571 ion chamber for reference dosimetry of high‐energy electron beams. These results will be useful as the AAPM continues to review their reference dosimetry protocols.

  15. Beam-energy and laser beam-profile monitor at the BNL LINAC

    SciTech Connect

    Connolly, R.; Briscoe, B.; Degen, C.; DeSanto, L.; Meng, W.; Minty, M.; Nayak, S.; Raparia, D.; Russo, T.

    2010-05-02

    We are developing a non-interceptive beam profile and energy monitor for H{sup -} beams in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. Electrons that are removed from the beam ions either by laser photodetachment or stripping by background gas are deflected into a Faraday cup. The beam profile is measured by stepping a narrow laser beam across the ion beam and measuring the electron charge vs. transverse laser position. There is a grid in front of the collector that can be biased up to 125kV. The beam energy spectrum is determined by measuring the electron charge vs. grid voltage. Beam electrons have the same velocity as the beam and so have an energy of 1/1836 of the beam protons. A 200MeV H{sup -} beam yields 109keV electrons. Energy measurements can be made with either laser-stripped or gas-stripped electrons.

  16. Quasimonoenergetic Electron Beams with Relativistic Energies and Ultrashort Duration from Laser-Solid Interactions at 0.5 kHz

    SciTech Connect

    Mordovanakis, Aghapi G.; Easter, James; Hou Bixue; Nees, John; Krushelnick, Karl; Naumova, Natalia; Popov, Konstantin; Rozmus, Wojciech; Masson-Laborde, Paul-Edouard; Sokolov, Igor; Mourou, Gerard; Glazyrin, Igor V.; Bychenkov, Valery

    2009-12-04

    We investigate the production of electron beams from the interaction of relativistically-intense laser pulses with a solid-density SiO{sub 2} target in a regime where the laser pulse energy is approxmJ and the repetition rate approxkHz. The electron beam spatial distribution and spectrum were investigated as a function of the plasma scale length, which was varied by deliberately introducing a moderate-intensity prepulse. At the optimum scale length of lambda/2, the electrons are emitted in a collimated beam having a quasimonoenergetic distribution that peaked at approx0.8 MeV. A highly reproducible structure in the spatial distribution exhibits an evacuation of electrons along the laser specular direction and suggests that the electron beam duration is comparable to that of the laser pulse. Particle-in-cell simulations which are in good agreement with the experimental results offer insights on the acceleration mechanism by the laser field.

  17. Quasimonoenergetic electron beams with relativistic energies and ultrashort duration from laser-solid interactions at 0.5 kHz.

    PubMed

    Mordovanakis, Aghapi G; Easter, James; Naumova, Natalia; Popov, Konstantin; Masson-Laborde, Paul-Edouard; Hou, Bixue; Sokolov, Igor; Mourou, Gérard; Glazyrin, Igor V; Rozmus, Wojciech; Bychenkov, Valery; Nees, John; Krushelnick, Karl

    2009-12-04

    We investigate the production of electron beams from the interaction of relativistically-intense laser pulses with a solid-density SiO(2) target in a regime where the laser pulse energy is approximately mJ and the repetition rate approximately kHz. The electron beam spatial distribution and spectrum were investigated as a function of the plasma scale length, which was varied by deliberately introducing a moderate-intensity prepulse. At the optimum scale length of lambda/2, the electrons are emitted in a collimated beam having a quasimonoenergetic distribution that peaked at approximately 0.8 MeV. A highly reproducible structure in the spatial distribution exhibits an evacuation of electrons along the laser specular direction and suggests that the electron beam duration is comparable to that of the laser pulse. Particle-in-cell simulations which are in good agreement with the experimental results offer insights on the acceleration mechanism by the laser field.

  18. Electron-electron interaction in ballistic electron beams

    NASA Astrophysics Data System (ADS)

    Müller, F.; Lengeler, B.; Schäpers, Th.; Appenzeller, J.; Förster, A.; Klocke, Th.; Lüth, H.

    1995-02-01

    The transport of ballistic electrons emitted and detected by adjacent point contacts in a two-dimensional electron gas (2DEG) in the system GaAs/AlxGa1-xAs was measured at 1.2 K as a function of the emitter current. Hot carriers with a surplus energy up to 15 meV above the Fermi level were generated by the current flow. It is shown that electron-electron scattering is the main limitation for the quasiparticle lifetime. The experimental data for the ballistic electron propagation from emitter to detector are explained without free parameters by a theory developed by Chaplik and by Giuliani and Quinn. In addition, it is shown that crossing ballistic electron beams in a 2DEG interact with one another, if one of the beams contains hot electrons in the zone of interaction. Experiments on the influence of impurities on the mean free path of ballistic electrons should be done with currents as low as 10 nA. Otherwise, the mean free path contains a contribution from electron-electron scattering. Electron-electron interaction of hot carriers is a serious basic limitation for future devices based on the transport of electrons in the mesoscopic transport regime.

  19. Observation of a variable sub-THz radiation driven by a low energy electron beam from a thermionic rf electron gun

    DOE PAGES

    Smirnov, A. V.; Agustsson, R.; Berg, W. J.; ...

    2015-09-29

    We report observations of an intense sub-THz radiation extracted from a ~3 MeV electron beam with a flat transverse profile propagating between two parallel oversized copper gratings with side openings. Low-loss radiation outcoupling is accomplished using a horn antenna and a miniature permanent magnet separating sub-THz and electron beams. A tabletop experiment utilizes a radio frequency thermionic electron gun delivering a thousand momentum-chirped microbunches per macropulse and an alpha-magnet with a movable beam scraper producing sub-mm microbunches. The radiated energy of tens of micro-Joules per radio frequency macropulse is demonstrated. The frequency of the radiation peak was generated and tunedmore » across two frequency ranges: (476–584) GHz with 7% instantaneous spectrum bandwidth, and (311–334) GHz with 38% instantaneous bandwidth. In this study, the prototype setup features a robust compact source of variable frequency, narrow bandwidth sub-THz pulses.« less

  20. Electron beam induced damage of NaNO{sub 3} single crystals: An energy, temperature, and quantum state resolved study

    SciTech Connect

    Petrik, N.G.; Knutsen, K.; Paparazzo, E.; Lea, S.; Camaioni, D.M.; Orlando, T.M.

    2000-02-24

    Electron beam induced damage of NaNO{sub 3} single crystals is examined using laser resonance enhanced multiphoton ionization detection of the neutral desorption products, post-irradiation temperature-programmed desorption (TPD), secondary electron emission microscopy (SEEM), and Auger electron spectroscopy (AES). The damage initially involves destruction of the nitrate group and production of O ({sup 3}P{sub J}) and NO ({sup 2}II) fragments with nonthermal energy distributions. Specifically, the O ({sup 3}P{sub J}) J state distribution measured at 100 eV incident electron energy is 5:1.5:0.25 for J = 2:1:0, the NO ({sup 2}II) vibrational state distribution is 1:0.56:0.35:0.40:0.23 for {nu} = 0:1:2:3:4, and the NO ({sup 2}II{sub 1/2,3/2}) rotational distribution has a high population of the upper ({sup 2}II{sub 3/2}) spin-orbit component. Production and desorption of these nonthermal fragments are dominated by the decay of {l{underscore}brace}NO{sub 3}{sup {minus}}{r{underscore}brace}*. At higher electron fluences, thermalized NO, O{sub 2}, and NO{sub 2} are also produced and released, through the NO{sub 2} is a minor product. The authors suggest that the formation and desorption of thermalized NO and O{sub 2} both involve NO{sub 2}{sup {minus}} defect states and unimolecular dissociation of NO{sub 3}{asterisk}. This is supported by the observation that the NO and O{sub 2} yields have the same temperature dependence which is well described by the sum of two Maxwell-Boltzmann type equations with activation energies of 0.16 {+-} 0.03 and 0.010 {+-} 0.004 eV. O{sub 2} gas is also released in post-irradiation thermal cycling from 110 to 440 K with peaks at {approximately}260 and {approximately}340 K. The authors associate the post-irradiation TPD of O{sub 2} with reactions involving O atoms released during thermal decomposition of {l{underscore}brace}NO{sub 2}{sup {minus}}{hor{underscore}ellipsis}O{r{underscore}brace} and ONOO{sup {minus}}. The SEEM image shows damage

  1. On the parameters of runaway electron beams and on electrons with an "anomalous" energy at a subnanosecond breakdown of gases at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Baksht, E. K.; Beloplotov, D. V.; Burachenko, A. G.; Kostyrya, I. D.; Lomaev, M. I.; Rybka, D. V.; Sorokin, D. A.

    2015-09-01

    The generation of runaway electron beams in gases at atmospheric pressure has been studied with a real picosecond accuracy. Their main parameters have been determined. It has been found that three groups of electrons can be separated at a subnanosecond voltage pulse in a runaway electron beam generated in air at atmospheric pressure. It has been proven that the duration of a beam pulse in air at atmospheric pressure behind an anode foil is ~100 ps.

  2. Beamed energy propulsion

    NASA Technical Reports Server (NTRS)

    Shoji, James M.

    1992-01-01

    Beamed energy concepts offer an alternative for an advanced propulsion system. The use of a remote power source reduces the weight of the propulsion system in flight and this, combined with the high performance, provides significant payload gains. Within the context of this study's baseline scenario, two beamed energy propulsion concepts are potentially attractive: solar thermal propulsion and laser thermal propulsion. The conceived beamed energy propulsion devices generally provide low thrust (tens of pounds to hundreds of pounds); therefore, they are typically suggested for cargo transportation. For the baseline scenario, these propulsion system can provide propulsion between the following nodes: (1) low Earth orbit to geosynchronous Earth orbit; (2) low Earth orbit to low lunar orbit; (3) low lunar orbit to low Mars orbit--only solar thermal; and (4) lunar surface to low lunar orbit--only laser thermal.

  3. 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.

  4. 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.

  5. Low energy electron beam irradiation effect on optical properties of nanopillar MQW InGaN/GaN structures

    SciTech Connect

    Yakimov, E. B.; Vergeles, P. S.; Polyakov, A. Y.; Jeon, Dae-Woo; Lee, In-Hwan

    2014-02-21

    The low energy electron beam irradiation (LEEBI) effect on optical properties of planar and nanopillar InGaN/GaN muliple quantum well light emitting structures was studied by the cathodoluminescence (CL) method. On the planar structures LEEBI leads to a formation of new InGaN-related emission bands red shifted in comparison with initial one at small irradiation doses and blue shifted at doses higher than 0.5 C/cm{sup 2}. It was observed that after dry etching used for the nanopillar formation the main InGaN-related emission line moves from 2.92 to 2.98 eV that can be explained by a strain relaxation in the quantum wells. The optical properties of nanopilars start to change under LEEBI at a dose of about one order of magnitude lower than that for planar structures. At high irradiation doses the behavior of both structures under LEEBI is similar. The results obtained were explained by the formation and reconstruction of quantum dots inside the quantum wells due to a point defect generation and redistribution stimulated by the electron beam irradiation.

  6. Pulsed electron beam precharger

    SciTech Connect

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

    1990-01-01

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

  7. Combined effects of nuclear and electronic energy losses in solids irradiated with a dual-ion beam

    SciTech Connect

    Thome, Lionel; Debelle, Aurelien; Garrido, Frederico; Trocellier, Patrick; Serruys, Yves; Miro, Sandrine

    2013-04-08

    Single and dual-beam irradiations of oxide (c-ZrO{sub 2}, MgO, Gd{sub 2}Ti{sub 2}O{sub 7}) and carbide (SiC) single crystals were performed to study combined effects of nuclear (S{sub n}) and electronic (S{sub e}) energy losses. Rutherford backscattering experiments in channeling conditions show that the S{sub n}/S{sub e} cooperation induces a strong decrease of the irradiation-induced damage in SiC and MgO and almost no effects in c-ZrO{sub 2} and Gd{sub 2}Ti{sub 2}O{sub 7}. The healing process is ascribed to electronic excitations arising from the electronic energy loss of swift ions. These results present a strong interest for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where expected cooperative S{sub n}/S{sub e} effects may lead to the preservation of the integrity of nuclear devices.

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

    SciTech Connect

    Singh, J.

    1996-12-01

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

  9. Nuclear astrophysics and electron beams

    SciTech Connect

    Schwenk, A.

    2013-11-07

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

  10. Characterization of the phantom material Virtual Water{sup TM} in high-energy photon and electron beams

    SciTech Connect

    McEwen, M.R.; Niven, D.

    2006-04-15

    The material Virtual Water{sup TM} has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water{sup TM} were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence--the water/Virtual Water{sup TM} dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement (<0.2%) between water and Virtual Water{sup TM} at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Wate{sup TM}. However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurements have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values.

  11. Doping of Graphene by Low-Energy Ion Beam Implantation: Structural, Electronic, and Transport Properties.

    PubMed

    Willke, Philip; Amani, Julian A; Sinterhauf, Anna; Thakur, Sangeeta; Kotzott, Thomas; Druga, Thomas; Weikert, Steffen; Maiti, Kalobaran; Hofsäss, Hans; Wenderoth, Martin

    2015-08-12

    We investigate the structural, electronic, and transport properties of substitutional defects in SiC-graphene by means of scanning tunneling microscopy and magnetotransport experiments. Using ion incorporation via ultralow energy ion implantation, the influence of different ion species (boron, nitrogen, and carbon) can directly be compared. While boron and nitrogen atoms lead to an effective doping of the graphene sheet and can reduce or raise the position of the Fermi level, respectively, (12)C(+) carbon ions are used to study possible defect creation by the bombardment. For low-temperature transport, the implantation leads to an increase in resistance and a decrease in mobility in contrast to undoped samples. For undoped samples, we observe in high magnetic fields a positive magnetoresistance that changes to negative for the doped samples, especially for (11)B(+)- and (12)C(+)-ions. We conclude that the conductivity of the graphene sheet is lowered by impurity atoms and especially by lattice defects, because they result in weak localization effects at low temperatures.

  12. Micro-nanopores fabricated by high-energy electron beam irradiation: suitable structure for controlling pesticide loss.

    PubMed

    Xiang, Yubin; Wang, Ning; Song, Jimei; Cai, Dongqing; Wu, Zhengyan

    2013-06-05

    Pesticide sprayed onto crop leaves tends to be washed off by rainwater and discharge into the environment through leaching and runoff, resulting in severe pollution to both soil and water. Here, to control pesticide loss, we developed a loss-control pesticide (LCP) by adding modified natural nanoclay (diatomite) through high-energy electron beam (HEEB) to traditional pesticide. After HEEB treatment, the originally clogged pores in diatomite opened, resulting in plenty of micro-nanopores in diatomite, which are beneficial for the pesticide molecules to access and be adsorbed. This pesticide-diatomite complex tended to be retained by the rough surface of crop leaves, displaying a high adhesion performance onto the leaves, so that the pesticide loss reduced, sufficient pesticide for crops was supplied, and the pollution risk of the pesticide could be substantially lowered.

  13. In situ degradation of antibiotic residues in medical intravenous infusion bottles using high energy electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Min; Zhang, Lele; Zhang, Guilong; Pang, Tao; Zhang, Xin; Cai, Dongqing; Wu, Zhengyan

    2017-01-01

    This study reported an immediate approach for the degradation of three antibiotic (amoxicillin, ofloxacin, and cefradine) residues in medical intravenous infusion bottles (MIIBs) using high energy electron beam (HEEB) irradiation. The effects of irradiation doses, initial concentrations, initial pH, and scavengers of active radicals on the degradation of three antibiotic residues (ARs) were investigated, and the results displayed that 97.02%, 97.61% and 96.87% of amoxicillin, ofloxacin, and cefradine residues could be degraded in situ through HEEB irradiation respectively. Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis demonstrated that ARs were mainly decomposed into inorganic ions and alkanes. Typically, the detailed degradation mechanism of ARs was also investigated, and the dominant active particle inducing the degradation of antibiotics during the HEEB irradiation process was demonstrated to be hydroxyl radical.

  14. In situ degradation of antibiotic residues in medical intravenous infusion bottles using high energy electron beam irradiation

    PubMed Central

    Wang, Min; Zhang, Lele; Zhang, Guilong; Pang, Tao; Zhang, Xin; Cai, Dongqing; Wu, Zhengyan

    2017-01-01

    This study reported an immediate approach for the degradation of three antibiotic (amoxicillin, ofloxacin, and cefradine) residues in medical intravenous infusion bottles (MIIBs) using high energy electron beam (HEEB) irradiation. The effects of irradiation doses, initial concentrations, initial pH, and scavengers of active radicals on the degradation of three antibiotic residues (ARs) were investigated, and the results displayed that 97.02%, 97.61% and 96.87% of amoxicillin, ofloxacin, and cefradine residues could be degraded in situ through HEEB irradiation respectively. Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis demonstrated that ARs were mainly decomposed into inorganic ions and alkanes. Typically, the detailed degradation mechanism of ARs was also investigated, and the dominant active particle inducing the degradation of antibiotics during the HEEB irradiation process was demonstrated to be hydroxyl radical. PMID:28045097

  15. Pore structure modification of diatomite as sulfuric acid catalyst support by high energy electron beam irradiation and hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Li, Chong; Zhang, Guilong; Wang, Min; Chen, Jianfeng; Cai, Dongqing; Wu, Zhengyan

    2014-08-01

    High energy electron beam (HEEB) irradiation and hydrothermal treatment (HT), were applied in order to remove the impurities and enlarge the pore size of diatomite, making diatomite more suitable to be a catalyst support. The results demonstrated that, through thermal, charge, impact and etching effects, HEEB irradiation could make the impurities in the pores of diatomite loose and remove some of them. Then HT could remove rest of them from the pores and contribute significantly to the modification of the pore size distribution of diatomite due to thermal expansion, water swelling and thermolysis effects. Moreover, the pore structure modification improved the properties (BET (Brunauer-Emmett-Teller) specific surface area, bulk density and pore volume) of diatomite and the catalytic efficiency of the catalyst prepared from the treated diatomite.

  16. Low energy antiproton beams

    NASA Astrophysics Data System (ADS)

    Klapisch, R.

    1992-04-01

    It was the invention of stochastic cooling by S. Van Meer that has allowed antiproton beams to become a powerful tool for the physicist. As a byproduct of the high energy proton-antiproton collider, a versatile low-energy facility, LEAR has been operating at CERN since 1984. The facility and its characteristics will be described as well as examples of its use for studying fundamental properties of the antiproton and for topics in atomic, nuclear and particle Physics.

  17. [Study of the influence of uniform transverse magnetic field on the dose distribution of high energy electron beam using Monte Carlo method].

    PubMed

    You, Shihu; Xu, Yun; Wu, Zhangwen; Hou, Qing; Guo, Chengjun

    2014-12-01

    In the present work, Monte Carlo simulations were employed to study the characteristics of the dose distribution of high energy electron beam in the presence of uniform transverse magnetic field. The simulations carried out the transport processes of the 30 MeV electron beam in the homogeneous water phantom with different magnetic field. It was found that the dose distribution of the 30 MeV electron beam had changed significantly because of the magnetic field. The result showed that the range of the electron beam was decreased obviously and it formed a very high dose peak at the end of the range, and the ratio of maximum dose to the dose of the surface was greatly increased. The results of this study demonstrated that we could change the depth dose distribution of electron beam which is analogous to the heavy ion by modulating the energy of the electron and magnetic field. It means that using magnetic fields in conjunction with electron radiation therapy has great application prospect, but it also has brought new challenges for the research of dose algorithm.

  18. Electron beam experiments at high altitudes

    SciTech Connect

    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 microAmps. 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 had distribution functions with 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 (several 10s of meters), 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.

  19. 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.

  20. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Astrophysics Data System (ADS)

    Chutjian, A.; Smith, Steven J.; Lozano, J. A.

    2002-11-01

    There is increasing emphasis within this decade on understanding energy balance and new phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, and the X-ray spectral return from the HETG on Chandra and the LETGS on XMM-Newton are just beginning. The line emissions are almost entirely from highly-charged ions (HCIs) of C, N, O, Ne, Mg, S, Si, Ca, and Fe. In addition, the Constellation-X mission, currently in the planning stages, will provide high-throughput X-ray spectroscopy up to photon energies of 0.12 nm (10 keV), where the primary line emitters will again be the HCIs. This array of space instruments is providing an overwhelming return of HCI spectral data from a variety of astrophysical objects. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma [1]. The JPL electron energy-loss and merged-beams approach [2] has been used to measure absolute collision strengths in a number of ions, with critical comparisons to the best available theories. Experimental methods will be reviewed, and results presented on experimental comparisons to R-Matrix and Breit-Pauli theoretical results in C3+[3], O2+[4], O5+[5], S2+[6], and Fe9+ [7]. Work is planned for comparisons in Mgq+, and higher charge states Fe(10-15)+. J. Lozano thanks the National Research Council for a fellowship though the NASA- NRC program. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and was supported under contract with the National Aeronautics and Space Administration.

  1. Fast magnetospheric echoes of energetic electron beams

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  2. Comparison of film measurements and Monte Carlo simulations of dose delivered with very high-energy electron beams in a polystyrene phantom

    SciTech Connect

    Bazalova-Carter, Magdalena; Liu, Michael; Palma, Bianey; Koong, Albert C.; Maxim, Peter G. E-mail: BWLoo@Stanford.edu; Loo, Billy W. E-mail: BWLoo@Stanford.edu; Dunning, Michael; McCormick, Doug; Hemsing, Erik; Nelson, Janice; Jobe, Keith; Colby, Eric; Tantawi, Sami; Dolgashev, Valery

    2015-04-15

    Purpose: To measure radiation dose in a water-equivalent medium from very high-energy electron (VHEE) beams and make comparisons to Monte Carlo (MC) simulation results. Methods: Dose in a polystyrene phantom delivered by an experimental VHEE beam line was measured with Gafchromic films for three 50 MeV and two 70 MeV Gaussian beams of 4.0–6.9 mm FWHM and compared to corresponding MC-simulated dose distributions. MC dose in the polystyrene phantom was calculated with the EGSnrc/BEAMnrc and DOSXYZnrc codes based on the experimental setup. Additionally, the effect of 2% beam energy measurement uncertainty and possible non-zero beam angular spread on MC dose distributions was evaluated. Results: MC simulated percentage depth dose (PDD) curves agreed with measurements within 4% for all beam sizes at both 50 and 70 MeV VHEE beams. Central axis PDD at 8 cm depth ranged from 14% to 19% for the 5.4–6.9 mm 50 MeV beams and it ranged from 14% to 18% for the 4.0–4.5 mm 70 MeV beams. MC simulated relative beam profiles of regularly shaped Gaussian beams evaluated at depths of 0.64 to 7.46 cm agreed with measurements to within 5%. A 2% beam energy uncertainty and 0.286° beam angular spread corresponded to a maximum 3.0% and 3.8% difference in depth dose curves of the 50 and 70 MeV electron beams, respectively. Absolute dose differences between MC simulations and film measurements of regularly shaped Gaussian beams were between 10% and 42%. Conclusions: The authors demonstrate that relative dose distributions for VHEE beams of 50–70 MeV can be measured with Gafchromic films and modeled with Monte Carlo simulations to an accuracy of 5%. The reported absolute dose differences likely caused by imperfect beam steering and subsequent charge loss revealed the importance of accurate VHEE beam control and diagnostics.

  3. Comparison of film measurements and Monte Carlo simulations of dose delivered with very high-energy electron beams in a polystyrene phantom.

    PubMed

    Bazalova-Carter, Magdalena; Liu, Michael; Palma, Bianey; Dunning, Michael; McCormick, Doug; Hemsing, Erik; Nelson, Janice; Jobe, Keith; Colby, Eric; Koong, Albert C; Tantawi, Sami; Dolgashev, Valery; Maxim, Peter G; Loo, Billy W

    2015-04-01

    To measure radiation dose in a water-equivalent medium from very high-energy electron (VHEE) beams and make comparisons to Monte Carlo (MC) simulation results. Dose in a polystyrene phantom delivered by an experimental VHEE beam line was measured with Gafchromic films for three 50 MeV and two 70 MeV Gaussian beams of 4.0-6.9 mm FWHM and compared to corresponding MC-simulated dose distributions. MC dose in the polystyrene phantom was calculated with the EGSnrc/BEAMnrc and DOSXYZnrc codes based on the experimental setup. Additionally, the effect of 2% beam energy measurement uncertainty and possible non-zero beam angular spread on MC dose distributions was evaluated. MC simulated percentage depth dose (PDD) curves agreed with measurements within 4% for all beam sizes at both 50 and 70 MeV VHEE beams. Central axis PDD at 8 cm depth ranged from 14% to 19% for the 5.4-6.9 mm 50 MeV beams and it ranged from 14% to 18% for the 4.0-4.5 mm 70 MeV beams. MC simulated relative beam profiles of regularly shaped Gaussian beams evaluated at depths of 0.64 to 7.46 cm agreed with measurements to within 5%. A 2% beam energy uncertainty and 0.286° beam angular spread corresponded to a maximum 3.0% and 3.8% difference in depth dose curves of the 50 and 70 MeV electron beams, respectively. Absolute dose differences between MC simulations and film measurements of regularly shaped Gaussian beams were between 10% and 42%. The authors demonstrate that relative dose distributions for VHEE beams of 50-70 MeV can be measured with Gafchromic films and modeled with Monte Carlo simulations to an accuracy of 5%. The reported absolute dose differences likely caused by imperfect beam steering and subsequent charge loss revealed the importance of accurate VHEE beam control and diagnostics.

  4. Feasibility of Parity-Violating Electron Scattering Experiments Below 1 GeV Beam Energy with a Toroidal Spectrometer

    NASA Astrophysics Data System (ADS)

    Bartlett, Kurtis

    2015-10-01

    The next generation of high precision parity-violating electron scattering experiments could potentially make use of a toroidal spectrometer to perform additional measurements of the proton's weak charge (Qwp) using a hydrogen target, a test of the Standard Model using a carbon target as well as possibly studying the neutron skin of heavier nuclei. I will present the results of recent Geant4 Monte-Carlo studies performed to test the feasibility of such a toroidal spectrometer at beam energies below 1 GeV employing a concept similar to that used by the recent JLab Qweak measurement. It appears that given sufficient beam time such a measurement could be complementary to the JLab measurement, but at a significantly lower Q2. The feasibility of measuring the neutron skin using such a spectrometer will also be discussed. The key issue for this latter type of measurement is the ability to achieve the necessary resolution to separate the elastic and first excited state. This work was supported in part by the National Science Foundation under Grant No. PHY-1206053.

  5. Effect of Energy Input on Microstructure and Mechanical Properties of Titanium Aluminide Alloy Fabricated by the Additive Manufacturing Process of Electron Beam Melting.

    PubMed

    Mohammad, Ashfaq; Alahmari, Abdulrahman M; Mohammed, Muneer Khan; Renganayagalu, Ravi Kottan; Moiduddin, Khaja

    2017-02-21

    Titanium aluminides qualify adequately for advanced aero-engine applications in place of conventional nickel based superalloys. The combination of high temperature properties and lower density gives an edge to the titanium aluminide alloys. Nevertheless, challenges remain on how to process these essentially intermetallic alloys in to an actual product. Electron Beam Melting (EBM), an Additive Manufacturing Method, can build complex shaped solid parts from a given feedstock powder, thus overcoming the shortcomings of the conventional processing techniques such as machining and forging. The amount of energy supplied by the electron beam has considerable influence on the final build quality in the EBM process. Energy input is decided by the beam voltage, beam scan speed, beam current, and track offset distance. In the current work, beam current and track offset were varied to reflect three levels of energy input. Microstructural and mechanical properties were evaluated for these samples. The microstructure gradually coarsened from top to bottom along the build direction. Whereas higher energy favored lath microstructure, lower energy tended toward equiaxed grains. Computed tomography analysis revealed a greater amount of porosity in low energy samples. In addition, the lack of bonding defects led to premature failure in the tension test of low energy samples. Increase in energy to a medium level largely cancelled out the porosity, thereby increasing the strength. However, this trend did not continue with the high energy samples. Electron microscopy and X-ray diffraction investigations were carried out to understand this non-linear behavior of the strength in the three samples. Overall, the results of this work suggest that the input energy should be considered primarily whenever any new alloy system has to be processed through the EBM route.

  6. Effect of Energy Input on Microstructure and Mechanical Properties of Titanium Aluminide Alloy Fabricated by the Additive Manufacturing Process of Electron Beam Melting

    PubMed Central

    Mohammad, Ashfaq; Alahmari, Abdulrahman M.; Mohammed, Muneer Khan; Renganayagalu, Ravi Kottan; Moiduddin, Khaja

    2017-01-01

    Titanium aluminides qualify adequately for advanced aero-engine applications in place of conventional nickel based superalloys. The combination of high temperature properties and lower density gives an edge to the titanium aluminide alloys. Nevertheless, challenges remain on how to process these essentially intermetallic alloys in to an actual product. Electron Beam Melting (EBM), an Additive Manufacturing Method, can build complex shaped solid parts from a given feedstock powder, thus overcoming the shortcomings of the conventional processing techniques such as machining and forging. The amount of energy supplied by the electron beam has considerable influence on the final build quality in the EBM process. Energy input is decided by the beam voltage, beam scan speed, beam current, and track offset distance. In the current work, beam current and track offset were varied to reflect three levels of energy input. Microstructural and mechanical properties were evaluated for these samples. The microstructure gradually coarsened from top to bottom along the build direction. Whereas higher energy favored lath microstructure, lower energy tended toward equiaxed grains. Computed tomography analysis revealed a greater amount of porosity in low energy samples. In addition, the lack of bonding defects led to premature failure in the tension test of low energy samples. Increase in energy to a medium level largely cancelled out the porosity, thereby increasing the strength. However, this trend did not continue with the high energy samples. Electron microscopy and X-ray diffraction investigations were carried out to understand this non-linear behavior of the strength in the three samples. Overall, the results of this work suggest that the input energy should be considered primarily whenever any new alloy system has to be processed through the EBM route. PMID:28772572

  7. SU-D-19A-01: Can Farmer-Type Ionization Chambers Be Used to Improve the Accuracy of Low-Energy Electron Beam Reference Dosimetry?

    SciTech Connect

    Muir, B R; McEwen, M R

    2014-06-01

    Purpose: To investigate the use of cylindrical Farmer-type ionization chambers to improve the accuracy of low-energy electron beam calibration. Historically, these chamber types have not been used in beams with incident energies less than 10 MeV (R{sub 5} {sub 0} < 4.3 cm) because early investigations suggested large (up to 5 %) fluence perturbation factors in these beams, implying that a significant component of uncertainty would be introduced if used for calibration. More recently, the assumptions used to determine perturbation corrections for cylindrical chambers have been questioned. Methods: Measurements are made with cylindrical chambers in Elekta Precise 4, 8 and 18 MeV electron beams. Several chamber types are investigated that employ graphite walls and aluminum electrodes with very similar specifications (NE2571, NE2505/3, FC65-G). Depth-ionization scans are measured in water in the 8 and 18 MeV beams. To reduce uncertainty from chamber positioning, measurements in the 4 MeV beam are made at the reference depth in Virtual Water™. The variability of perturbation factors is quantified by comparing normalized response of various chambers. Results: Normalized ion chamber response varies by less than 0.7 % for similar chambers at average electron energies corresponding to that at the reference depth from 4 or 6 MeV beams. Similarly, normalized measurements made with similar chambers at the reference depth in the 4 MeV beam vary by less than 0.4 %. Absorbed dose calibration coefficients derived from these results are stable within 0.1 % on average over a period of 6 years. Conclusion: These results indicate that the uncertainty associated with differences in fluence perturbations for cylindrical chambers with similar specifications is only 0.2 %. The excellent long-term stability of these chambers in both photon and electron beams suggests that these chambers might offer the best performance for all reference dosimetry applications.

  8. Very high-energy electron (VHEE) beams in radiation therapy; Treatment plan comparison between VHEE, VMAT, and PPBS.

    PubMed

    Schüler, Emil; Eriksson, Kjell; Hynning, Elin; Hancock, Steven L; Hiniker, Susan M; Bazalova-Carter, Magdalena; Wong, Tony; Le, Quynh-Thu; Loo, Billy W; Maxim, Peter G

    2017-06-01

    The aim of this study was to evaluate the performance of very high-energy electron beams (VHEE) in comparison to clinically derived treatment plans generated with volumetric modulated arc therapy (VMAT) and proton pencil beam scanning (PPBS) technology. We developed a custom optimization script that could be applied automatically across modalities to eliminate operator bias during IMRT optimization. Four clinical cases were selected (prostate cancer, lung cancer, pediatric brain tumor, and head and neck cancer (HNC)). The VHEE beams were calculated in the EGSnrc/DOSXYZnrc Monte Carlo code for 100 and 200 MeV beams. Treatment plans with VHEE, VMAT, and PPBS were optimized in a research version of RayStation using an in-house developed script to minimize operator bias between the different techniques. The in-house developed script generated similar or superior plans to the clinically used plans. In the comparisons between the modalities, the integral dose was lowest for the PPBS-generated plans in all cases. For the prostate case, the 200 MeV VHEE plan showed reduced integral dose and reduced organ at risk (OAR) dose compared to the VMAT plan. For all other cases, both the 100 and the 200 MeV VHEE plans were superior to the VMAT plans, and the VHEE plans showed better conformity and lower spinal cord dose in the pediatric brain case and lower brain stem dose in the HNC case when compared to the PPBS plan. The automated optimization developed in this study generated similar or superior plans as compared to the clinically used plan and represents an unbiased approach to compare treatment plans generated for different modalities. In the present study, we also show that VHEE plans are similar or superior to VMAT plans with reduced mean OAR dose and increased target conformity for a variety of clinical cases, and VHEE plans can even achieve reductions in OAR doses compared to PPBS plans for shallow targets. With increased VHEE energy, better conformity and even higher

  9. Final report to US Department of Energy: Cyclotron autoresonance accelerator for electron beam dry scrubbing of flue gases

    SciTech Connect

    Hirshfield, J.L.

    2001-05-25

    Several designs have been built and operated of microwave cyclotron autoresonance accelerators (CARA's) with electron beam parameters suitable for remediation of pollutants in flue gas emissions from coal-burning power plants. CARA designs have also been developed with a TW-level 10.6 micron laser driver for electron acceleration from 50 to 100 MeV, and with UHF drivers for proton acceleration to over 500 MeV. Dose requirements for reducing SO2, NOx, and particulates in flue gas emissions to acceptable levels have been surveyed, and used to optimize the design of an electron beam source to deliver this dose.

  10. 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.

  11. Absolute cascade-free cross-sections for the 2S to 2P transition in Zn(+) using electron-energy-loss and merged-beams methods

    NASA Technical Reports Server (NTRS)

    Smith, Steven J.; Man, K.-F.; Chutjian, A.; Mawhorter, R. J.; Williams, I. D.

    1991-01-01

    Absolute cascade-free excitation cross-sections in an ion have been measured for the resonance 2S to 2P transition in Zn(+) using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross-sections over the energy range of the calculations.

  12. Absolute cascade-free cross-sections for the 2S to 2P transition in Zn(+) using electron-energy-loss and merged-beams methods

    NASA Technical Reports Server (NTRS)

    Smith, Steven J.; Man, K.-F.; Chutjian, A.; Mawhorter, R. J.; Williams, I. D.

    1991-01-01

    Absolute cascade-free excitation cross-sections in an ion have been measured for the resonance 2S to 2P transition in Zn(+) using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross-sections over the energy range of the calculations.

  13. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-01-01

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

  14. Magnetron sputtering system for coatings deposition with activation of working gas mixture by low-energy high-current electron beam

    NASA Astrophysics Data System (ADS)

    Gavrilov, N. V.; Kamenetskikh, A. S.; Men'shakov, A. I.; Bureyev, O. A.

    2015-11-01

    For the purposes of efficient decomposition and ionization of the gaseous mixtures in a system for coatings deposition using reactive magnetron sputtering, a low-energy (100-200 eV) high-current electron beam is generated by a grid-stabilized plasma electron source. The electron source utilizes both continuous (up to 20 A) and pulse-periodic mode of discharge with a self-heated hollow cathode (10-100 A; 0.2 ms; 10-1000 Hz). The conditions for initiation and stable burning of the high-current pulse discharge are studied along with the stable generation of a low-energy electron beam within the gas pressure range of 0.01 - 1 Pa. It is shown that the use of the electron beam with controllable parameters results in reduction of the threshold values both for the pressure of gaseous mixture and for the fluxes of molecular gases. Using such a beam also provides a wide range (0.1-10) of the flux density ratios of ions and sputtered atoms over the coating surface, enables an increase in the maximum pulse density of ion current from plasma up to 0.1 A, ensures an excellent adhesion, optimizes the coating structure, and imparts improved properties to the superhard nanocomposite coatings of (Ti,Al)N/a-Si3N4 and TiC/-a-C:H. Mass-spectrometric measurements of the beam-generated plasma composition proved to demonstrate a twofold increase in the average concentration of N+ ions in the Ar-N2 plasma generated by the high-current (100 A) pulsed electron beam, as compared to the dc electron beam.

  15. CRYSTALLINE BEAMS AT HIGH ENERGIES.

    SciTech Connect

    WEI, J.; OKAMOTO, H.; YURI, Y.; SESSLER, A.; MACHIDA, S.

    2006-06-23

    Previously it was shown that by crystallizing each of the two counter-circulating beams, a much larger beam-beam tune shift can be tolerated during the beam-beam collisions; thus a higher luminosity can be reached for colliding beams [1]. On the other hand, crystalline beams can only be formed at energies below the transition energy ({gamma}{sub T}) of the accelerators [2]. In this paper, we investigate the formation of crystals in a high-{gamma}{sub T} lattice that also satisfies the maintenance condition for a crystalline beam [3].

  16. 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.

  17. 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.

  18. Impulsive solar X-ray bursts: Bremsstrahlung radiation from a beam of electrons in the solar chromosphere and the total energy of solar flares

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1973-01-01

    Analysis of various aspects of impulsive X-ray bursts (IXB's) has lead to the consideration of a model where the X-rays are produced by bremsstrahlung radiation from a beam of electrons directed toward the photosphere. It was found that in general the X-ray spectrum from such a beam will fall off more rapidly than when the effect of the beaming of radiation is neglected. Furthermore, the spectral index of the resulting X-rays appears to increase by about unity for X-ray energies 100 kev, a fact which may explain the observed cutoff in the spectrum of the IXB's. It is also shown that in such a model there is sufficient energy in the form of nonthermal electrons to explain the total energy (approximately 10 to the 32nd power ergs) of a flare.

  19. Convergent-beam low energy electron diffraction (CBLEED) and the measurement of surface dipole layers.

    PubMed

    Spence, J C H; Poon, H C; Saldin, D K

    2004-02-01

    We propose the formation of LEED patterns using a highly convergent beam forming a probe of nanometer dimensions. A reflection rocking curve may then be recorded in many diffraction orders simultaneously. Multiple scattering calculations show that the intensity variations within these rocking curves is as sensitive to the parameters describing the surface dipole layer as conventional I/V scans. However the data may be collected from areas sufficiently small to avoid defects and surface steps, radiation damage controlled by use of low voltages, and the information depth selected by choice of the (constant) voltage. We briefly discuss also the application of this method to oxides and the formation of atomic-resolution scanning images in an idealized instrument in which coherent diffracted LEED orders overlap.

  20. Electron beams in solar flares

    NASA Technical Reports Server (NTRS)

    Aschwanden, Markus J.; Dennis, Brian R.; Benz, Arnold O.

    1994-01-01

    A list of publications resulting from this program includes 'The Timing of Electron Beam Signatures in Hard X-Ray and Radio: Solar Flare Observations by BATSE/Compton Gamma-Ray Observatory and PHOENIX'; 'Coherent-Phase or Random-Phase Acceleration of Electron Beams in Solar Flares'; 'Particle Acceleration in Flares'; 'Chromospheric Evaporation and Decimetric Radio Emission in Solar Flares'; 'Sequences of Correlated Hard X-Ray and Type 3 Bursts During Solar Flares'; and 'Solar Electron Beams Detected in Hard X-Rays and Radiowaves.' Abstracts and reprints of each are attached to this report.

  1. Electron beam gaseous pollutants treatments

    SciTech Connect

    Chmielewski, A.G.

    1995-12-31

    High energy electrons create thousands of ions and free radicals along their path. In consequence radiolytical processes take place that with eventual usage of additional reactants at proper physical gas conditions may lead to new air pollution control technologies. Three examples are discusses: (1) SO{sub 2} and NO{sub x} removal (combustion flue gases); (2) volatile organic compounds removal, and (3) SO{sub 2} high concentration flue gas treatment. The experimental tests, depending on the subject has been performed at two different units. One is an industrial pilot plant constructed in electropower station on a coal fired boiler, with gas flow up to 20,000 cNmph, equipped in two electron accelerators. 50 kW power and 800 keV each. The second is a laboratory installation with the flow up to 400 cNmph, in this case flue gases are produced by two gas fired boilers and research setup is furnished in an accelerator of 20 kW beam power and electrons energy up to 2 MeV. The results of the tests performed at laboratory and industrial pilot plant are discussed. On this basis technical and economical evaluation of full size industrial installation has been prepared.

  2. HIGH ENERGY ELECTRON INJECTION (E-BEAM) TECHNOLOGY FOR THE EX-SITU TREATMENT OF MTBE-CONTAMINATED GROUNDWATER INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This Innovative Technology Evaluation Report documents the results of a demonstration of the high-energy electron injection (E-Beam) technology in application to groundwater contaminated with methyl t-butyl ether (MtBE) and with benzene, toluene, ethylbenzene, and xylenes (BTEX)....

  3. HIGH ENERGY ELECTRON INJECTION (E-BEAM) TECHNOLOGY FOR THE EX-SITU TREATMENT OF MTBE-CONTAMINATED GROUNDWATER INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This Innovative Technology Evaluation Report documents the results of a demonstration of the high-energy electron injection (E-Beam) technology in application to groundwater contaminated with methyl t-butyl ether (MtBE) and with benzene, toluene, ethylbenzene, and xylenes (BTEX)....

  4. Electron--positron beam--plasma experiments

    NASA Astrophysics Data System (ADS)

    Gilbert, S. J.; Kurz, C. K.; Greaves, R. G.; Surko, C. M.

    1997-11-01

    Electron-positron plasmas possess unique properties due to inherent symmetries between the charge species. The ability to accumulate large numbers of cold positrons in Penning-Malmberg traps has made the study of such plasmas possible in the laboratory.(R.G. Greaves, M.D. Tinkle and C.M. Surko, Phys. Plas.) 1 1439 (1994) In the first experiment of this type we studied a beam-plasma system by transmitting an electron beam through a positron plasma in a Penning trap.(R.G. Greaves and C.M. Surko, Phys. Rev. Lett.), 74 3846 (1995) These earlier measurements were obtained using a hot cathode electron source, for which the large beam energy spreads ( ~ 0.5 eV) made it impossible to explore the low energy regime of this beam-plasma system, where the strongest interaction occurs. We report new growth rate measurements obtained using a novel low-energy, cold (Δ E ≈ 0.05 eV) electron beam based on the extraction of electrons stored in a Penning trap.(S.J. Gilbert et al.), Appl. Phys. Lett., 70 1944 (1997). The measured growth rates for a transit time instability are found to be in excellent agreement with a cold fluid theory by D.H.E. Dubin over the range of accessible energies (0.1--3 eV).

  5. All-optical Time-resolved Measurement of Laser Energy Modulation in a Relativistic Electron Beam

    SciTech Connect

    Xiang, D.; Colby, E.; Dunning, M.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T.O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Weathersby, S.; Woodley, M.; /SLAC

    2012-02-15

    Hamiltonian light-front theory has been proposed as a promising method for solving bound states problems in quantum field theory a long time ago, see, e.g., the review article[1] for its various advantages compared to the traditional instant-form theories. Recently the Basis Light-Front Quantization (BLFQ) approach [2, 3] has been developed as a nonperturbative approach to solve Hamiltonian light-front quantum field theory. Numerical efficiency is a key advantage of this approach. The basic idea of BLFQ is to represent the theory in an optimal basis which respects many symmetries of the theory and thus minimizes the dimensionality of the Hamiltonian for a fixed precision. Specifically, the BLFQ approach employs a plane wave basis in the light-front longitudinal direction and a 2D harmonic oscillator basis in the transverse directions. In previous work [3] this approach has been applied to evaluate the anomalous magnetic moment of electrons which are confined in an external trap with an extrapolation to the zero trap limit. In this work we extend and improve this approach in several aspects including the direct evaluation of a free electron system. This article is organized as follows: In Sec. 2 we discuss the key extensions and improvements made in this work over Ref [3]; in Sec. 3 we present the numerical results for the electron anomalous magnetic moment evaluated in different harmonic oscillator bases and compare to the perturbation theory result. Finally we conclude and give an outline for future works in Sec. 4.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Ohmi, Kazuhito

    2016-11-01

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

  8. Improved electron-beam welder

    NASA Technical Reports Server (NTRS)

    Smock, R. A.; Taylor, R. A.; Wall, W. A.

    1978-01-01

    Report describes comprehensive test-and-evaluation program designed to improve performance of 7.5 kW electron-beam welder. Report describes prototype and seventeen changes incorporated to improve performance.

  9. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    SciTech Connect

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R.

    2014-04-28

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  10. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    NASA Astrophysics Data System (ADS)

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R.

    2014-04-01

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  11. Pyroelectric-field driven defects diffusion along c-axis in ZnO nanobelts under high-energy electron beam irradiation

    SciTech Connect

    Ding, Yong Liu, Ying; Niu, Simiao; Wu, Wenzhuo; Wang, Zhong Lin

    2014-10-21

    When ZnO nanobelts are exposed to a high-dose electron probe of several nanometers to hundred nanometers in diameter inside a transmission electron microscope, due to the radiolysis effect, part of oxygen atoms will be ejected into the vacuum and leaving a Zn-ion rich surface with a pit appearance at both the electron-entrance and electron-exit surfaces. At the same time, a temperature distribution is created around the electron probe due to local beam heating effect, which generates a unidirectional pyroelectric field. This pyroelectric field is strong enough to drive Zn ions moving along its positive c-axis direction as interstitial ions. In the first case, for the ZnO nanobelts with c-axis lie in their large surfaces, defects due to the aggregation of Zn interstitial ions will be formed at some distances of 30–50 nm approximately along the c-axis direction from the electron beam illuminated area. Alternatively, for the ZnO nanobelts with ±(0001) planes as their large surfaces, the incident electron beam is along its c-axis and the generated pyroelectric field will drive the interstitial Zn-ions to aggregate at the Zn terminated (0001) surface where the local electrical potential is the lowest. Such electron beam induced damage in ZnO nanostructures is suggested as a result of Zn ion diffusion driven by the temperature gradient induced pyroelectric field along c-axis. Our study shows a radiation damage caused by electron beam in transmission electron microscopy, especially when the electron energy is high.

  12. Improvement of energy efficiency and filter technology in the electron beam dry scrubber process

    NASA Astrophysics Data System (ADS)

    Paur, Hanns-R.; Baumann, Werner; Lindner, Wolfgang; Mätzing, Hartmut

    Energy efficiency of the simultaneous removal of NO x and SO 2 from flue gas by the EBDS process may be improved by applying multiple irradiation with intermediate product scrubbing. The product, which is a mixture of ammonium sulphate and nitrate, can be filtered using bag filters and gravel bed filters yielding a by-product which is suitable for agricultural purposes. Due to the recent development of high power accelerators the costs of the EBDS process are now competitive when compared to conventional flue gas treatment methods.

  13. Precisely-controlled fabrication of single ZnO nanoemitter arrays and their possible application in low energy parallel electron beam exposure.

    PubMed

    He, H; She, J C; Huang, Y F; Deng, S Z; Xu, N S

    2012-03-21

    Precisely-controlled fabrication of single ZnO nanoemitter arrays and their possible application in low energy parallel electron beam exposure are reported. A well defined polymethyl methacrylate (PMMA) nanohole template was employed for local solution-phase growth of single ZnO nanoemitter arrays. Chlorine plasma etching for surface smoothing and pulsed-laser illumination in nitrogen for nitrogen doping were performed, which can significantly enhance the electron emission and improve the emitter-to-emitter uniformity in performance. Mechanisms responsible for the field emission enhancing effect are proposed. Low voltage (368 V) e-beam exposure was performed by using a ZnO nanoemitter array and a periodical hole pattern (0.72-1.26 μm in diameter) was produced on a thin (25 nm) PMMA. The work demonstrates the feasibility of utilizing single ZnO nano-field emitter arrays for low voltage parallel electron beam lithography.

  14. Using the optical-klystron effect to increase and measure the intrinsic beam energy spread in free-electron-laser facilities

    NASA Astrophysics Data System (ADS)

    Prat, Eduard; Ferrari, Eugenio; Reiche, Sven; Schietinger, Thomas

    2017-04-01

    We present a setup based on the optical klystron concept, consisting of two undulator modules separated by a magnetic chicane, that addresses two issues in free-electron-laser (FEL) facilities. On the one hand, it allows increasing the intrinsic energy spread of the beam at the source, which is useful to counteract the harmful microbunching instability. This represents an alternative method to the more conventional laser heater with the main advantage that no laser system is required. On the other hand, the setup can be used to reconstruct the initial beam energy spread, whose typical values in FEL injectors around 1 keV are very difficult to measure with standard procedures.

  15. Dual-Cathode Electron-Beam Source

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  16. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    SciTech Connect

    Thomé, Lionel Debelle, Aurélien; Garrido, Frédérico; Sattonnay, Gaël; Mylonas, Stamatis; Velisa, Gihan; Miro, Sandrine; Trocellier, Patrick; Serruys, Yves

    2015-03-14

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (S{sub n}) and Electronic (S{sub e}) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (S{sub n} and S{sub e}), whereas single low-energy irradiation (S{sub n} alone) or even sequential (S{sub n} + S{sub e}) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between S{sub n} and S{sub e} in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery S{sub n}/S{sub e} effects may preserve the integrity of nuclear devices.

  17. Generation of high-energy electron-positron pairs in the collision of a laser-accelerated electron beam with a multipetawatt laser

    NASA Astrophysics Data System (ADS)

    Lobet, M.; Davoine, X.; d'Humières, E.; Gremillet, L.

    2017-04-01

    Generation of electron-positron pairs via the multiphoton Breit-Wheeler process in an all-optical scheme will be made possible on forthcoming high-power laser facilities through the collision of wakefield-accelerated GeV electrons with a counter-propagating laser pulse of 1 022- 1 023 W cm-2 peak intensity. By means of integrated 3D particle-in-cell simulations, we show that the production of high-density sources of ultrarelativistic electron-positron pairs is within the reach of soon-to-be-available laser systems. Under physical conditions accessible to the dual-beam CILEX-Apollon facility, we find that the generated positrons can carry a total charge of 0.05-1 nC, with a mean energy of 100-400 MeV and an angular divergence of 0.01-0.1 rad. The variations of the positron source's properties with respect to the laser parameters are also examined.

  18. Suprathermal electrons produced by Beam-Plasma-Discharge

    SciTech Connect

    Sharp, W.E.

    1982-08-01

    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.

  19. 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.

  20. 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.

  1. Enhanced thermotolerance and ethanol tolerance in Saccharomyces cerevisiae mutated by high-energy pulse electron beam and protoplast fusion.

    PubMed

    Zhang, Min; Xiao, Yu; Zhu, Rongrong; Zhang, Qin; Wang, Shi-Long

    2012-11-01

    To increase thermotolerance and ethanol tolerance in Saccharomyces cerevisiae strain YZ1, the strategies of high-energy pulse electron beam (HEPE) and three rounds of protoplast fusion were explored. The YF31 strain had the characteristics of resistant to high-temperature, high-ethanol tolerance, rapid growth and high yield. The YF31 could grow on plate cultures up to 47 °C, containing 237.5 g L(-1) of ethanol. In particular, the mutant strain YF31 generated 94.2 ± 4.8 g L(-1) ethanol from 200 g glucose L(-1) at 42 °C, which was 2.48 times the production of the wild strain YZ1. Results demonstrated that the variant phenotypes from the strains screening by HEPE irradiation could be used as parent stock for yeast regeneration and the protoplast fusion technology is sufficiently powerful in combining suitable characteristics in a single strain for ethanol fermentation.

  2. First year of Mark-J: physics with high energy electron-positron colliding beams. Report No. 107

    SciTech Connect

    Aachen DESY M.I.T. NIKHEF Peking Collaboration

    1980-04-01

    This report reviews the experimental investigation of high energy e/sup +/e/sup -/ interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, West Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the online data collection and the offline analysis are also outlined. Results are presented on tests of quantum electrodynamics using e/sup +/e/sup -/ ..-->.. e/sup +/e/sup -/, ..mu../sup +/..mu../sup -/ and tau/sup +/tau/sup -/, on the measurement of R, the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant ..cap alpha../sub s/.

  3. Observation of optical Smith-Purcell radiation at an electron beam energy of 855 MeV.

    PubMed

    Kube, G; Backe, H; Euteneuer, H; Grendel, A; Hagenbuck, F; Hartmann, H; Kaiser, K H; Lauth, W; Schöpe, H; Wagner, G; Walcher, Th; Kretzschmar, M

    2002-05-01

    Smith-Purcell radiation, generated when a beam of charged particles passes close to the surface of a diffraction grating, has been studied in the visible spectral range at wavelengths of 360 and 546 nm with the low emittance 855 MeV electron beam of the Mainz Microtron MAMI. The beam focused to a spot size of 4 microm (full width at half maximum) passed over optical diffraction gratings of echelle profiles with blaze angles of 0.8 degrees, 17.27 degrees, and 41.12 degrees and grating periods of 0.833 and 9.09 microm. Taking advantage of the specific emission characteristics of Smith-Purcell radiation a clear separation from background components, such as diffracted synchrotron radiation from upstream beam optical elements and transition radiation, was possible. The intensity scales with a modified Bessel function of the first kind as a function of the distance between electron beam and grating surface. Experimental radiation factors have been determined and compared with calculations on the basis of Van den Berg's theory [P.M. Van den Berg, J. Opt. Soc. Am. 63, 689 (1973)]. Fair agreement has been found for gratings with large blaze angles while the measurement with the shallow grating (blaze angle 0.8 degrees ) is at variance with this theory. Finally, the optimal operational parameters of a Smith-Purcell radiation source in view of already existing powerful undulator sources are discussed.

  4. Observation of optical Smith-Purcell radiation at an electron beam energy of 855 MeV

    NASA Astrophysics Data System (ADS)

    Kube, G.; Backe, H.; Euteneuer, H.; Grendel, A.; Hagenbuck, F.; Hartmann, H.; Kaiser, K. H.; Lauth, W.; Schöpe, H.; Wagner, G.; Walcher, Th.; Kretzschmar, M.

    2002-05-01

    Smith-Purcell radiation, generated when a beam of charged particles passes close to the surface of a diffraction grating, has been studied in the visible spectral range at wavelengths of 360 and 546 nm with the low emittance 855 MeV electron beam of the Mainz Microtron MAMI. The beam focused to a spot size of 4 μm (full width at half maximum) passed over optical diffraction gratings of echelle profiles with blaze angles of 0.8°, 17.27°, and 41.12° and grating periods of 0.833 and 9.09 μm. Taking advantage of the specific emission characteristics of Smith-Purcell radiation a clear separation from background components, such as diffracted synchrotron radiation from upstream beam optical elements and transition radiation, was possible. The intensity scales with a modified Bessel function of the first kind as a function of the distance between electron beam and grating surface. Experimental radiation factors have been determined and compared with calculations on the basis of Van den Berg's theory [P.M. Van den Berg, J. Opt. Soc. Am. 63, 689 (1973)]. Fair agreement has been found for gratings with large blaze angles while the measurement with the shallow grating (blaze angle 0.8°) is at variance with this theory. Finally, the optimal operational parameters of a Smith-Purcell radiation source in view of already existing powerful undulator sources are discussed.

  5. 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.

  6. Comparison of the IAEA TRS-398 and AAPM TG-51 absorbed dose to water protocols in the dosimetry of high-energy photon and electron beams.

    PubMed

    Huq, M S; Andreo, P; Song, H

    2001-11-01

    The International Atomic Energy Agency (IAEA TRS-398) and the American Association of Physicists in Medicine (AAPM TG-51) have published new protocols for the calibration of radiotherapy beams. These protocols are based on the use of an ionization chamber calibrated in terms of absorbed dose to water in a standards laboratory's reference quality beam. This paper compares the recommendations of the two protocols in two ways: (i) by analysing in detail the differences in the basic data included in the two protocols for photon and electron beam dosimetry and (ii) by performing measurements in clinical photon and electron beams and determining the absorbed dose to water following the recommendations of the two protocols. Measurements were made with two Farmer-type ionization chambers and three plane-parallel ionization chamber types in 6, 18 and 25 MV photon beams and 6, 8, 10, 12, 15 and 18 MeV electron beams. The Farmer-type chambers used were NE 2571 and PTW 30001, and the plane-parallel chambers were a Scanditronix-Wellhöfer NACP and Roos, and a PTW Markus chamber. For photon beams, the measured ratios TG-51/TRS-398 of absorbed dose to water Dw ranged between 0.997 and 1.001, with a mean value of 0.999. The ratios for the beam quality correction factors kQ were found to agree to within about +/-0.2% despite significant differences in the method of beam quality specification for photon beams and in the basic data entering into kQ. For electron beams, dose measurements were made using direct N(D,w) calibrations of cylindrical and plane-parallel chambers in a 60Co gamma-ray beam, as well as cross-calibrations of plane-parallel chambers in a high-energy electron beam. For the direct N(D,w) calibrations the ratios TG-51/TRS-398 of absorbed dose to water Dw were found to lie between 0.994 and 1.018 depending upon the chamber and electron beam energy used, with mean values of 0.996, 1.006, and 1.017, respectively, for the cylindrical, well-guarded and not well

  7. 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.

  8. 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.

  9. An Electron Target/cooler for Extremely Low-Energy Ion Beams at the Electrostatic Storage Ring

    NASA Astrophysics Data System (ADS)

    Tanabe, Tetsumi; Noda, Koji; Watanabe, Ikuo

    2002-12-01

    An electrostatic storage ring for studying atomic and molecular science has been operational at KEK since May, 2000. The ring has a circumference of 8 m and can store light-to-heavy ions with an E/q of up to 30 keV. Light ions are produced with an electron cyclotron resonance ion source, while bio-molecular ions are produced with an electrospray ion source The measured 1/e-lifetimes of stored single-charge ions injected from the electron cyclotron resonance ion source are from 10 to 50 s. On the other hand, ions from the electrospray ion source have lifetimes from 12 to 20 s. These lifetimes are long enough to cool vibrationally excited molecular ions, and their intensities are tolerable for practical use, like atomic collision experiments. In order to study electron-ion collisions, an electron beam target has been designed, which will be installed in a straight section of the ring. The structure of the target is almost the same as an electron cooler consisting of an adiabatically expanded electron beam; the target can also function as an electron cooler for light-mass ions.

  10. Absolute and relative dose measurements with Gafchromic trade mark sign EBT film for high energy electron beams with different doses per pulse

    SciTech Connect

    Fiandra, Christian; Ragona, Riccardo; Ricardi, Umberto; Anglesio, Silvia; Giglioli, Francesca Romana

    2008-12-15

    The authors have evaluated the accuracy, in absolute and relative dose measurements, of the Gafchromic trade mark sign EBT film in pulsed high-energy electron beams. Typically, the electron beams used in radiotherapy have a dose-per-pulse value of less than 0.1 mGy/pulse. However, very high dose-per-pulse electron beams are employed in certain linear accelerators dedicated to intraoperatory radiation therapy (IORT). In this study, the absorbed dose measurements with Gafchromic trade mark sign EBT in both low (less than 0.3 mGy per pulse) and high (30 and 70 mGy per pulse) dose-per-pulse electron beams were compared with ferrous sulfate chemical Fricke dosimetry (operated by the Italian Primary Standard Dosimetry Laboratory), a method independent of the dose per pulse. A summary of Gafchromic trade mark sign EBT in relative and absolute beam output determination is reported. This study demonstrates the independence of Gafchromic trade mark sign EBT absorption as a function of dose per pulse at different dose levels. A good agreement (within 3%) was found with Fricke dosimeters for plane-base IORT applicators. Comparison with a diode detector is presented for relative dose measurements, showing acceptable agreement both in the steep dose falloff zone and in the homogeneous dose region. This work also provides experimental values for recombination correction factor (K{sub sat}) of a Roos (plane parallel) ionization chamber calculated on the basis of theoretical models for charge recombination.

  11. Electrostatic and whistler instabilities excited by an electron beam

    NASA Astrophysics Data System (ADS)

    An, Xin; Bortnik, Jacob; Van Compernolle, Bart; Decyk, Viktor; Thorne, Richard

    2017-07-01

    The electron beam-plasma system is ubiquitous in the space plasma environment. Here, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency (ωpe) is larger than the electron cyclotron frequency (Ωe). The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slower-growing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity and (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between the beam electrons and electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on the ratio of ωpe/Ωe. In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region, whereas beam-generated whistler waves transport energy away from the beam.

  12. Gamma Putty dosimetric studies in electron beam

    PubMed Central

    Gloi, Aime M.

    2016-01-01

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

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

    PubMed

    Becker, Reinard; Kester, Oliver

    2010-02-01

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

  14. Storage-ring Electron Cooler for Relativistic Ion Beams

    SciTech Connect

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

    2016-05-01

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

  15. 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.

  16. Beam Characterizations at Femtosecond Electron Beam Facility

    SciTech Connect

    Rimjaem, S.; Jinamoon, V.; Kangrang, M.; Kusoljariyakul, K.; Saisut, J.; Thongbai, C.; Vilaithong, T.; Rhodes, M.W.; Wichaisirimongkol, P.; Wiedemann, H.; /SLAC

    2006-03-17

    The SURIYA project at the Fast Neutron Research Facility (FNRF) has been established and is being commissioning to generate femtosecond (fs) electron bunches. Theses short bunches are produced by a system consisting of an S-band thermionic cathode RF-gun, an alpha magnet (a-magnet) serving as a magnetic bunch compressor, and a SLAC-type linear accelerator (linac). The characteristics of its major components and the beam characterizations as well as the preliminary experimental results will be presented and discussed in this paper.

  17. 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.

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

    DOEpatents

    Birx, Daniel L.; Reginato, Louis L.

    1987-01-01

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

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

    DOEpatents

    Birx, Daniel L.; Reginato, Louis L.

    1988-01-01

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

  20. SU-E-T-472: Characterization of the Very High Energy Electrons, ISO - 250 MeV (VHEE) Beam Generated by ALPHA-X Laser Wakefield Accelerator Beam Line for Utilization in Monte Carlo Simulation for Biomedical Experiment Planning.

    PubMed

    Moskvin, V; Subiel, A; Desrosiers, C; Wiggins, M; Maryanski, M; Mendonca, M; Boyd, M; Sorensen, A; Cipiccia, S; Issac, R; Welsh, G; Brunetti, E; Aniculaesei, C; Jaroszynski, D A

    2012-06-01

    Progress in the development of compact high-energy pulsed laser- plasma wakefield accelerators is opening up the potential for using Very High Energy Electron (VHEEs) beams in the range of 150 - 250 MeV for biomedical studies. Initial experiments using VHEE for this purpose have been carried out using the ALPHA-X laser-plasma wakefield accelerator beam line at the University of Strathclyde, Glasgow, UK. The purpose of this investigation is to use Monte Carlo simulations to plan experiments and compare with characterization of the interaction of the VHEE beam using a dosimeter. An experiment using the VHEE beam to irradiate a muscle-equivalent BANG polymer gel dosimeter has been carried out. Simulations have been used to prepare for the experiments. These were undertaken using the expected average energy for a pulse set and an energy spread approximated by Gaussian distribution. The model was implemented in FLUKA Monte Carlo code with follow up modeling using the Geant4 toolkit. The results have been compared with 1mm̂3 voxel laser CT based measurements of the dose deposited in the BANG dosimeter and with measurement of the induced radioactivity. The results of the measured dose from induced radioactivity have been compared with data from the FLUKA simulations. The beam model based on an average energy of particles in irradiation gives an acceptable estimate of the induced radioactivity and the dose deposited in the BANG dosimeter. Comparison with the dosimeter scanned profiles shows that the structure of the spectra of VHEE beams in the experiment and secondary scattered particles in the beam line should be accounted for in any model. Such model description of the VHEE beam for the ALPHA-X beam line has been developed. Monte Carlo simulations using the FLUKA code is an efficient way to plan a VHEE experiment and analyze data from measurements. © 2012 American Association of Physicists in Medicine.

  1. Evaluation of various operational and dosimetric parameters of an industrial electron beam accelerator of 2 MeV energy

    NASA Astrophysics Data System (ADS)

    Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

    2014-07-01

    An industrial type 2 MeV/20 kW ILU-6 electron beam accelerator is operational in India for development of applications and technology demonstration to the Indian Industry in the field of polymer modifications (cross-linking and degradation). In order to adjust the treatment conditions and to control the good operation of the accelerator, it is necessary to study dose response as a function of various operational parameters. An experimental procedure for calibrating Cellulose Triacetate (CTA) film strip dosimeters in electron beam using total absorption graphite calorimeters is discussed and compared it with the results obtained from gamma calibration. Dosimetry data for process application, where the irradiation target is plane polymer sheet, have been obtained under various operational parameters.

  2. Strain localization parameters of AlCu4MgSi processed by high-energy electron beams

    SciTech Connect

    Lunev, A. G. Nadezhkin, M. V.; Konovalov, S. V.; Teresov, A. D.

    2015-10-27

    The influence of the electron beam surface treatment of AlCu4MgSi on the strain localization parameters and on the critical strain value of the Portevin–Le Chatelier effect has been considered. The strain localization parameters were measured using speckle imaging of the specimens subjected to the constant strain rate uniaxial tension at a room temperature. Impact of the surface treatment on the Portevin–Le Chatelier effect has been investigated.

  3. A 2.45 GHz electron cyclotron resonance proton ion source and a dual-lens low energy beam transporta)

    NASA Astrophysics Data System (ADS)

    Zhang, W. H.; Ma, H. Y.; Yang, Y.; Wu, Q.; Zhang, X. Z.; Wang, H.; Ma, B. H.; Feng, Y. C.; Fang, X.; Guo, J. W.; Cao, Y.; Li, X. X.; Zhu, Y. H.; Li, J. Y.; Sha, S.; Lu, W.; Lin, S. H.; Guo, X. H.; Zhao, H. Y.; Sun, L. T.; Xie, D. Z.; Peng, S. X.; Liu, Z. W.; Zhao, H. W.

    2012-02-01

    The structure and preliminary commissioning results of a new 2.45 GHz ECR proton ion source and a dual-lens low energy beam transport (LEBT) system are presented in this paper. The main magnetic field of the ion source is provided by a set of permanent magnets with two small electro-solenoid magnets at the injection and the extraction to fine tune the magnetic field for better microwave coupling. A 50 keV pulsed proton beam extracted by a three-electrode mechanism passes through the LEBT system of length of 1183 mm. This LEBT consists of a diagnosis chamber, two Glaser lenses, two steering magnets, and a final beam defining cone. A set of inner permanent magnetic rings is embedded in each of the two Glaser lenses to produce a flatter axial-field to reduce the lens aberrations.

  4. A 2.45 GHz electron cyclotron resonance proton ion source and a dual-lens low energy beam transport

    SciTech Connect

    Zhang, W. H.; Ma, H. Y.; Wu, Q.; Zhang, X. Z.; Wang, H.; Ma, B. H.; Feng, Y. C.; Fang, X.; Guo, J. W.; Li, X. X.; Zhu, Y. H.; Li, J. Y.; Guo, X. H.; Zhao, H. Y.; Sun, L. T.; Xie, D. Z.; Liu, Z. W.; Zhao, H. W.; Yang, Y.; Cao, Y.; and others

    2012-02-15

    The structure and preliminary commissioning results of a new 2.45 GHz ECR proton ion source and a dual-lens low energy beam transport (LEBT) system are presented in this paper. The main magnetic field of the ion source is provided by a set of permanent magnets with two small electro-solenoid magnets at the injection and the extraction to fine tune the magnetic field for better microwave coupling. A 50 keV pulsed proton beam extracted by a three-electrode mechanism passes through the LEBT system of length of 1183 mm. This LEBT consists of a diagnosis chamber, two Glaser lenses, two steering magnets, and a final beam defining cone. A set of inner permanent magnetic rings is embedded in each of the two Glaser lenses to produce a flatter axial-field to reduce the lens aberrations.

  5. Characteristics of the Shanghai high-temperature superconducting electron-beam ion trap and studies of the space-charge effect under ultralow-energy operating conditions

    NASA Astrophysics Data System (ADS)

    Tu, B.; Lu, Q. F.; Cheng, T.; Li, M. C.; Yang, Y.; Yao, K.; Shen, Y.; Lu, D.; Xiao, J.; Hutton, R.; Zou, Y.

    2017-10-01

    A high-temperature superconducting electron-beam ion trap (EBIT) has been set up at the Shanghai EBIT Laboratory for spectroscopic studies of low-charge-state ions. In the study reported here, beam trajectory simulations are implemented in order to provide guidance for the operation of this EBIT under ultralow-energy conditions, which has been successfully achieved with a full-transmission electron-beam current of 1-8.7 mA at a nominal electron energy of 30-120 eV. The space-charge effect is studied through both simulations and experiments. A modified iterative formula is proposed to estimate the space-charge potential of the electrons and shows very good agreement with the simulation results. In addition, space-charge compensation by trapped ions is found in extreme ultraviolet spectroscopic measurements of carbon ions and is studied through simulation of ion behavior in the EBIT. Based on the simulation results, the ion-cloud radius, ion density, and electron-ion overlap are obtained.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Electron-beam transmission through a micrometer-sized tapered-glass capillary: Dependence on incident energy and angular tilt angle

    NASA Astrophysics Data System (ADS)

    Wickramarachchi, S. J.; Ikeda, T.; Dassanayake, B. S.; Keerthisinghe, D.; Tanis, J. A.

    2016-08-01

    An experimental study of 500- and 1000-eV incident electrons transmitted through a micrometer-sized funnel-shaped (tapered) glass capillary with inlet diameter 0.80 mm, outlet diameter 0.10 mm, and a length of 35 mm is reported. The properties of the electron beam transmitted were measured as a function of the emerging angle and the incident energy dependence. The angular profiles were found to be comprised of up to three peaks for both 500 and 1000 eV showing evidence for transmission going straight through the capillary without interacting with the walls (direct), as well as transmission resulting from Coulomb deflection of the electrons from a negative charge patch or by scattering from nuclei close to the surface of the capillary (indirect). The energy spectra show that elastically transmitted electrons dominate at 500 eV for increasing sample tilt angles up to ˜5.0°, while inelastic processes dominate for 1000 eV already at tilt angles of ˜1.0°. The angular width of the emitted electrons was found to constitute a narrow beam for direct (˜0.4°) and indirect (<0.6° for 500 eV and <1.0° for 1000 eV) transmission for both energies with the widths decreasing for the largest tilt angles measured and approaching the inherent resolution (˜0.3°) of the electron analyzer.

  12. 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.

  13. Beam damage suppression of low-kappa porous Si-O-C films by cryo-electron-energy loss spectroscopy (EELS).

    PubMed

    Otsuka, Yuji; Shimizu, Yumiko; Tanaka, Isao

    2009-04-01

    Porous Si-O-C films with lower dielectric constant (kappa) relative to silicon dioxide have been widely studied as inter-layer dielectrics in new-generation microelectronic devices. On the analysis of the film by transmission electron microscopy (TEM), it is susceptible of beam damage during both sample preparation by a focused ion beam (FIB) technique and TEM observation. We use electron energy loss spectroscopy (EELS) to quantify the magnitude of the beam damage during these processes. The intensity of the 285-eV peak in C-K electron energy loss near edge structures (ELNES) is enhanced by the damage, which can be ascribed to the formation of the C=C double bonds as a result of the decomposition of the methyl groups by the beam. The use of cryo-holder for TEM at 100 K is found to be essential to reduce the damage of the low-kappa layers. The lowering of the acceleration voltage of FIB down to 5 keV does not change the spectra. Since the FIB damage is localized at the surface, the use of thick regions in the TEM foil such as 130 nm is preferred to reduce the superposition of EELS of the damaged region on those from the sample of interest.

  14. 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.

  15. SU-E-T-635: Quantitative Study On Beam Flatness Variation with Beam Energy Change

    SciTech Connect

    Li, J S; Eldib, A; Ma, C; Lin, M

    2014-06-15

    Purpose: Beam flatness check has been proposed for beam energy check for photon beams with flattering filters. In this work, beam flatness change with beam energy was investigated quantitatively using the Monte Carlo method and its significance was compared with depth dose curve change. Methods: Monte Carlo simulations for a linear accelerator with flattering filter were performed with different initial electron energies for photon beams of 6MV and 10MV. Dose calculations in a water phantom were then perform with the phase space files obtained from the simulations. The beam flatness was calculated based on the dose profile at 10 cm depth for all the beams with different initial electron energies. The percentage depth dose (PDD) curves were also analyzed. The dose at 10cm depth (D10) and the ratio of the dose at 10cm and 20cm depth (D10/D20) and their change with the beam energy were calculated and compared with the beam flatness variation. Results: It was found that the beam flatness variation with beam energy change was more significant than the change of D10 and the ratio between D10 and D20 for both 6MV and 10MV beams. Half MeV difference on the initial electron beam energy brought in at least 20% variation on the beam flatness but only half percent change on the ratio of D10 and D20. The change of D10 or D20 alone is even less significant. Conclusion: The beam energy impact on PDD is less significant than that on the beam flatness. If the PDD is used for checking the beam energy, uncertainties of the measurement could possibly disguise its change. Beam flatness changes more significantly with beam energy and therefore it can be used for monitoring the energy change for photon beams with flattering filters. However, other factors which may affect the beam flatness should be watched as well.

  16. Electron beam irradiation of high density polyethylene pellets for thermal energy storage. Final report of Task 1 and Task 2, January 5, 1979-January 4, 1980

    SciTech Connect

    Davison, J.E.; Salyer, I.O.

    1980-05-01

    The objective of this project was to define the electron beam irradiation conditions required to prepare thermally form stable high crystallinity polyethylene (HDPE) pellets which are suitable for thermal energy storage (TES) applications in the temperature interval of 120/sup 0/ to 140/sup 0/C. The optimum material and conditions for electron beam x-linking via evaluation of thermal form stability and retained heat of fusion of HDPE pellets in a laboratory (5 lb) TES unit was defined. 250 pounds of crosslinked HDPE pellets under the optimum conditions defined in Task 1 were manufactured and evaluated for stability to extensive thermocycling in a pilot plant TES unit. Four different HDPE specimens were irradiated under different conditions of the total radiation dose received by the pellets, the electron beam accelerating potential, the electron beam current, the effect of inert atmospheres during irradiation processing, and the effect of stirring the HDPE pellets during the irradiation processing. The experimental values of the heat of fusion and the melting temperature of the irradiated HDPE pellets were measured and compared to the values of the as-received pellets to evaluate the effect of irradiation processing. The results showed that HDPE pellets irradiated to a dose of 8 megarads have sufficient thermal stability and retained heat of fusion to be used as TES material. The manufacture of 15,000 lb of cross linked HDPE pellets for large-scale evaluation TES material for home heating and cooling systems is recommended. (LCL)

  17. Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes

    SciTech Connect

    Kyriakou, Ioanna; Emfietzoglou, Dimitris; Garcia-Molina, Rafael; Abril, Isabel; Kostarelos, Kostas

    2011-09-01

    The effect of bulk and surface excitations to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes (MWNTs) is studied using the dielectric formalism. Calculations are based on a semiempirical dielectric response function for MWCNTs determined by means of a many-pole plasmon model with parameters adjusted to available experimental spectroscopic data under theoretical sum-rule constrains. Finite-size effects are considered in the context of electron gas theory via a boundary correction term in the plasmon dispersion relations, thus, allowing a more realistic extrapolation of the electronic excitation spectrum over the whole energy-momentum plane. Energy-loss differential and total inelastic scattering cross sections as a function of electron energy and distance from the surface, valid over the energy range {approx}50-30,000 eV, are calculated with the individual contribution of bulk and surface excitations separated and analyzed for the case of normally incident and escaping electrons. The sensitivity of the results to the various approximations for the spatial dispersion of the electronic excitations is quantified. Surface excitations are shown to have a strong influence upon the shape and intensity of the energy-loss differential cross section in the near surface region whereas the general notion of a spatially invariant inelastic mean free path inside the material is found to be of good approximation.

  18. Measurement of Space Charges in Dielectric Materials by Pulse Electro-acoustic Method after Irradiation by High-energy Electron Beam

    NASA Astrophysics Data System (ADS)

    Xiaogang, Qin; Kai, Li; Mayali; Xiaoquan, Zheng; Xiaodong, Liu

    2009-01-01

    Dielectric materials are widely used in space environment. When they are irradiated, charges will accumulate in the bulk and on the surface of the material, leading to pulse discharge events that can cause permanent changes in their physical and chemical structure. In this paper, a special method called PEA (pulse electro-acoustic) was used to measure and analyze the space charging of several dielectric materials after they have been irradiated by different high-energy electron beams.

  19. Ferroelectric electron beam sources

    NASA Astrophysics Data System (ADS)

    Flechtner, D.; Flechtner, D.; Ivers, J. D.; Kerslick, G. S.; Nation, J. A.; Schächter, L.; Zhang, Ge

    1995-06-01

    Ferroelectric materials offer the possibility of compact electron sources, with modest requirements to initiate the emission process. We are studying such sources as possible injectors for microwave generation. The source consists of a polarized ferroelectric ceramic disk with silver electrodes coated on both faces. The front electrode consists of a periodic grid created by etching the silver to expose a line pattern of ceramic. This electrode functions as the cathode in a planar diode geometry with an accelerating gap adjustable from 0.1 to 5 cm. A rapid change in the polarization state of the ceramic is achieved by applying a 1-2 kV, 150 ns pulse between the electrodes of the ferroelectric. Early work used a coaxial cable to maintain an anode potential of up to 1 kV across the A-K gap. The emitted electron current was measured as a function of the gap spacing and the anode potential. The current varies linearly with the anode voltage, up to 1 kV, for gaps <10 mm, and typically exceeds the Child-Langmuir current density by at least two orders of magnitude. Current densities in excess of 70 A/cm2 have been measured. More recent work has used a 300 ns pulse forming network to apply a potential of up to 15 kV at the anode. Results of emittance and scaling measurements under these conditions are reported.

  20. Mycosis fungoides. Electron beam therapy.

    PubMed

    Spittle, M F

    1977-01-01

    The most effective treatment of late mycosis fungoides is total skin electron beam therapy. The beam at the Hammersmith Hospital in London has been adapted to treat these patients. Patients with advanced disease who have failed more conservative methods of treatment are irradiated. The electron beam is modified by the use of carbon and copper scatterers to produce an 80 percent depth dose at 5.5, 8 and 11.5 millimeters below the skin surface. The dose achieved in most patients is between 1500 rads and 2600 rads given in 10 to 13 treatments over 5-7 weeks. Recently the higher dose range has been employed and lithium flouride studies have shown that giving these doses from each of 4 fields, the dose achieved on the skin is approximately twice the given dose. The management of patients and the effects of treatment are discussed.

  1. Radiative cooling of relativistic electron beams

    SciTech Connect

    Huang, Zhirong

    1998-05-01

    Modern high-energy particle accelerators and synchrotron light sources demand smaller and smaller beam emittances in order to achieve higher luminosity or better brightness. For light particles such as electrons and positrons, radiation damping is a natural and effective way to obtain low emittance beams. However, the quantum aspect of radiation introduces random noise into the damped beams, yielding equilibrium emittances which depend upon the design of a specific machine. In this dissertation, the author attempts to make a complete analysis of the process of radiation damping and quantum excitation in various accelerator systems, such as bending magnets, focusing channels and laser fields. Because radiation is formed over a finite time and emitted in quanta of discrete energies, he invokes the quantum mechanical approach whenever the quasiclassical picture of radiation is insufficient. He shows that radiation damping in a focusing system is fundamentally different from that in a bending system. Quantum excitation to the transverse dimensions is absent in a straight, continuous focusing channel, and is exponentially suppressed in a focusing-dominated ring. Thus, the transverse normalized emittances in such systems can in principle be damped to the Compton wavelength of the electron, limited only by the Heisenberg uncertainty principle. In addition, he investigates methods of rapid damping such as radiative laser cooling. He proposes a laser-electron storage ring (LESR) where the electron beam in a compact storage ring repetitively interacts with an intense laser pulse stored in an optical resonator. The laser-electron interaction gives rise to rapid cooling of electron beams and can be used to overcome the space charge effects encountered in a medium energy circular machine. Applications to the designs of low emittance damping rings and compact x-ray sources are also explored.

  2. Pulsed electron beam generator for application in materials science

    NASA Astrophysics Data System (ADS)

    Geerk, J.; Ratzel, F.

    1980-08-01

    A pulsed electron beam generator for the purpose of transient annealing was developed. The principle of operation of the generator is the production of an electron beam by means of a triggered vacuum discharge burning between metallic electrodes. The maximum energy of the electrons of a pulsed beam may be varied between 10 keV and 25 keV. The pulse length is about 300 nsec. The energy density at the sample location can be easily adjusted between 0.3 and 2.5 Joules/cm(2). The diameter of the electron beam is about 5 cm.

  3. Picosecond runaway electron beams in air

    SciTech Connect

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

    2012-01-15

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

  4. 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.

  5. Study of the evolution of the atomic composition of thin NbN films under irradiation with mixed ion beams by methods of electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Dement'eva, M. M.; Prikhod'ko, K. E.; Gurovich, B. A.; Kutuzov, L. V.; Komarov, D. A.

    2016-11-01

    The variation in the atomic composition of ultrathin NbN films under irradiation by mixed ion beams to a doze of 4 dpa (for nitrogen) is experimentally studied by methods of electron energy loss spectroscopy with a transmission electron microscope in the transmission scan mode on cross-cut samples. The behavior of the substitution of nitrogen atoms by oxygen atoms has been established; it is characterized by changing the composition of the conducting part of the film from NbN to NbNO.

  6. 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.

  7. Attosecond slicing of an LWFA produced electron beam

    NASA Astrophysics Data System (ADS)

    Sears, C. M. S.; Buck, A.; Schmid, K.; Veisz, L.; Herrmann, D.; Mikhailova, J.; Tautz, R.; Krausz, F.

    2009-05-01

    Recent years have seen rapid improvement in the quality of electron beams produced by wakefields in plasmas. The electron beams produced have inherently short durations and high peak current. To further shorten the pulse duration of these beams for future applications, an experiment is proposed to produce a single sub-femtosecond slice of electrons via an Inverse Free Electron Laser interaction (IFEL) with a few cycle laser pulse. The IFEL is followed by a combined function, permanent magnet quadrupole triplet chicane that both disperses the beam transversely while simultaneously focusing, allowing for efficient energy collimation to select the attosecond slice. Simulations are presented showing the expected electron slice characteristics.

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

    SciTech Connect

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

    2001-06-01

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

  9. Fast magnetospheric echoes of energetic electron beams

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  10. Absolute dose measurements by means of a small cylindrical ionization chamber for very high dose per pulse high energy electron beams

    SciTech Connect

    Karaj, E.; Righi, S.; Di Martino, F.

    2007-03-15

    Very high dose per pulse (3-13 cGy/pulse) high energy electron beams are currently produced by special linear accelerators (linac) dedicated to Intra Operative Radiation Therapy (IORT). The electron beams produced by such linacs are collimated by special Perspex applicators of various size and cylindrically shaped. The biggest problems from the dosimetric point of view are caused by the high dose-per-pulse values and the use of inclined applicators. In this work measurements of absolute dose for the inclined applicators were done by using a small cylindrical ionization chamber, type CC01 (Wellhofer), a parallel plane ionization chamber type Markus (PTW 23343) and radiochromic films type EBT. We show a method which allows calculating the quality correction factors for CC01 chamber with an uncertainty of 1% and the absolute dose value for the inclined applicators using CC01 with an uncertainty of 3.1% for electron beams of energy of 6 and 7 MeV produced by the linac dedicated to IORT Novac7.

  11. Emittance improvement of the electron cyclotron resonance high intensity light ion source proton beam by gas injection in the low energy beam transport

    NASA Astrophysics Data System (ADS)

    Beauvais, P.-Y.; Ferdinand, R.; Gobin, R.; Lagniel, J. M.; Leroy, P.-A.; Celona, L.; Ciavola, G.; Gammino, S.; Pottin, B.; Sherman, J.

    2000-03-01

    SILHI is the ECR high intensity light ion source studied in France at C.E.A. Saclay. This is the source for the injector of the high intensity proton injector prototype developed by a CNRS-IN2P3 collaboration. 80 mA at 95 keV beams with a rms normalized r-r' emittance lower than 0.3 π mm mrad and a proton fraction better than 85% are currently produced. Recently, it has been found that the injection in the low energy beam transport of a buffer gas had a strong effect on the emittance measured 1 m downstream of the focusing solenoid. By adding several gases (H2, N2, Ar, Kr), improvements as great as a factor of 3 have been observed. The emittance has been measured by means of an r-r' emittance measurement unit equipped with a sampling hole and a wire profile monitor, both moving across the beam. Simultaneously, the space charge compensation factor is measured using a four-grid analyzer unit. In this article all results of these experiments are presented and discussed. A first explanation of the emittance reduction phenomenon and possible consequences on the injector operation is given.

  12. 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.

  13. 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)

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  16. Electron Beam IEMP Simulation Development

    DTIC Science & Technology

    1975-08-01

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

  17. 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…

  18. 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…

  19. Wavelength and Intensity Dependence of the Standing Wave Mechanism in the Near-IR Regime in Producing High Energy Backwards Electron Beams

    NASA Astrophysics Data System (ADS)

    Ngirmang, Gregory; Orban, Chris; Feister, Scott; Morrison, John; Chowdhury, Enam; Roquemore, William

    2016-10-01

    Laser-plasma interactions involving ultra-short ultra-intense, near IR or IR wavelength lasers represent a novel regime, specifically inducing relativistic dynamics of charges at lower intensities than required for current ultra-intense lasers. We present 2D(3 v) Particle-in-Cell(PIC) simulations using the LSP code that produce super-ponderomotive MeV electron beams from ultra-short ultra-intense IR or Near-IR laser beams incident on targets with significant pre-plasma. We perform simulations across different wavelengths, including 800 nanometer, 3 microns, and 10 microns. We also simulate different pulse energies varying from tens of microjoules to tens of joules, and different scale lengths of pre-plasma. The accelerated electrons energies reach super-ponderomotive energies that scale roughly with the normalized vector potential, in line with the standing wave acceleration mechanism discussed in Orban et al. The angular spectrum of ejected electrons in all cases are similar, displaying preferred angles as suggested by the elaborations on the standing wave mechanism explained in Ngirmang, et al.

  20. 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.

  1. Hollow Electron Beam Collimator: R and D Status Report

    SciTech Connect

    Stancari, G.; Drozhdin, A.; Kuznetsov, G.; Shiltsev, V.; Valishev, A.; Vorobiev, L.; Kabantsev, A.

    2010-11-04

    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.

  2. Hollow Electron Beam Collimator: R&D Status Report

    NASA Astrophysics Data System (ADS)

    Stancari, G.; Drozhdin, A.; Kuznetsov, G.; Shiltsev, V.; Valishev, A.; Vorobiev, L.; Kabantsev, A.

    2010-11-01

    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.

  3. Plasma and ion barrier for electron beam spot stability

    NASA Astrophysics Data System (ADS)

    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.

  4. Diffracted transition radiation of an ultra-high-energy relativistic electron beam in a thin single-crystal wafer

    NASA Astrophysics Data System (ADS)

    Blazhevich, S. V.; Noskov, A. V.

    2016-10-01

    We consider diffracted transition radiation (DTR) emitted by high-energy relativistic electrons crossing a thin single-crystal wafer in the Laue geometry. The expression describing the DTR angular density is derived for the case where the electron path length in the target is much smaller than the X-ray wave extinction length in the crystal and the kinematic nature of this expression is demonstrated. It is shown that the DTR angular density in a thin target is proportional to the target thickness.

  5. Diffracted transition radiation of an ultra-high-energy relativistic electron beam in a thin single-crystal wafer

    SciTech Connect

    Blazhevich, S. V.; Noskov, A. V.

    2016-10-15

    We consider diffracted transition radiation (DTR) emitted by high-energy relativistic electrons crossing a thin single-crystal wafer in the Laue geometry. The expression describing the DTR angular density is derived for the case where the electron path length in the target is much smaller than the X-ray wave extinction length in the crystal and the kinematic nature of this expression is demonstrated. It is shown that the DTR angular density in a thin target is proportional to the target thickness.

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

    NASA Astrophysics Data System (ADS)

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

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

  7. 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

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

    SciTech Connect

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

    1997-06-01

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

  9. Effect of electron-electron interaction on hot ballistic electron beams

    NASA Astrophysics Data System (ADS)

    Schäpers, Th.; Krüger, M.; Appenzeller, J.; Förster, A.; Lengeler, B.; Lüth, H.

    1995-06-01

    Electron-electron scattering of ballistic electrons in a two-dimensional electron gas was studied as a function of the electron excess energy above the Fermi energy and of temperature. At low temperatures of 1.4 K it is found that for excess energies of approximately 30% of the Fermi energy the electrons in a ballistic electron beam are already scattered significantly due to electron-electron interaction. A very good agreement between our experimental data and theory was found, when the measured data were compared with numerical calculations based on a theory of Giuliani and Quinn [Phys. Rev. B 26, 4421 (1982)], while the agreement was only poor for the analytical approximation of the electron-electron scattering rate.

  10. Electron beam stimulated spin reorientation

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

  11. 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

  12. Collimation Studies with Hollow Electron Beams

    SciTech Connect

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

    2011-08-01

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

  13. New shielding materials for clinical electron beams.

    PubMed

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

    2006-09-01

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

  14. 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.

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

    SciTech Connect

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

    2013-07-08

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

  16. Measuring the Fluence of Clinical Electron Beams

    NASA Astrophysics Data System (ADS)

    Zaini, Mehran

    1995-01-01

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

  17. 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.

  18. Modelling of electron beam absorption in complex geometries

    NASA Astrophysics Data System (ADS)

    Klassen, Alexander; Bauereiß, Andreas; Körner, Carolin

    2014-02-01

    Computational modelling of processes that involve highly energetic electrons like electron beam melting, welding, drilling or electron beam lithography, to name but a few, requires information about the attenuation of the electron beam as it passes through the sample. Depth-dose curves as a function of electron energy, target material as well as local surface obliquity have to be provided in situ during the calculation. The most efficient way to address this issue is by employing mathematical expressions. Therefore, we propose an electron beam model based on a set of semi-empirical equations available from different published literature and on theoretical considerations. Particular stress is thereby put on accuracy and the range of validity of the theoretical approach by comparison with experimental data. Finally, we apply our model to powder-bed based additive manufacturing. The numerical results demonstrate that electron beam absorption and depth of penetration have a strong influence on the quality of the fabricated product.

  19. Low-energy operation of the Livermore electron beam ion traps: Atomic spectroscopy of Si V, S VII, and Ar IX

    SciTech Connect

    Lepson, J K; Beiersdorfer, P

    2004-01-02

    As part of a project to compile a comprehensive catalog of astrophysically relevant emission lines, we used the low-energy capability of the Lawrence Livermore electron beam ion traps to extend the spectroscopy of neon-like ions and the neighboring charge states to silicon, sulfur, and argon. They present wavelength data of Si V and demonstrate the effect of collisional deexcitation of electric dipole forbidden lines on the 2-3 L-shell spectra of Si V, S VII, and Ar IX.

  20. Increasing the electric strength of vacuum insulation by treating the electrodes with a low-energy, high-current electron beam

    SciTech Connect

    Batrakov, A.V.; Nazarov, D.S.; Ozur, G.E.

    1996-12-31

    The paper is devoted to the study of how the irradiation of the electrode surface with a low-energy, high-current electron beam affects the prebreakdown current and the electric strength of the vacuum insulation. This study is an extension of the work whose results were presented at the XVI ISDEIV. Experiments have been performed for 0.1-mm vacuum gaps formed by refractory-metal electrodes and for millimeter vacuum gaps with a pulsed voltage of amplitude 250 kV and duration 30-100 ns.

  1. Beam-beam interaction study of medium energy eRHIC

    SciTech Connect

    Hao,Y.; Litvinenko, V. N.; Ptitsyn, V.

    2009-07-15

    Medium Energy eRHIC (MeRHIC), the first stage design of eRHIC, includes a multi-pass ERL that provides 4GeV high quality electron beam to collide with the ion beam of RHIC. It delivers a minimum luminosity of 10{sup 32} cm{sup -2}s{sup -1}. Beam-beam effects present one of major factors limiting the luminosity of colliders. In this paper, both beam-beam effects on the electron beam and the proton beam in MeRHIC are investigated. The beam-beam interaction can induce a head-tail type instability of the proton beam referred to as the kink instability. Thus, beam stability conditions should be established to avoid proton beam loss. Also, the electron beam transverse disruption by collisions has to be evaluated to ensure that the beam quality is good enough for the energy recovery pass. The relation of proton beam stability, electron disruption and consequential luminosity are carried out after thorough discussion.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  3. 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.

  4. Space-charge compensation measurements in electron cyclotron resonance ion source low energy beam transport lines with a retarding field analyzer

    SciTech Connect

    Winklehner, D.; Leitner, D. Cole, D.; Machicoane, G.; Tobos, L.

    2014-02-15

    In this paper we describe the first systematic measurement of beam neutralization (space charge compensation) in the ECR low energy transport line with a retarding field analyzer, which can be used to measure the potential of the beam. Expected trends for the space charge compensation levels such as increase with residual gas pressure, beam current, and beam density could be observed. However, the overall levels of neutralization are consistently low (<60%). The results and the processes involved for neutralizing ion beams are discussed for conditions typical for ECR injector beam lines. The results are compared to a simple theoretical beam plasma model as well as simulations.

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

    NASA Astrophysics Data System (ADS)

    Ding, George X.

    1995-01-01

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

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Mirian, N. S.; Maraghechi, B.

    2013-08-01

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

  8. High electronic excitations and ion beam mixing effects in high energy ion irradiated Fe/Si multilayers

    SciTech Connect

    Bauer, P.; Dufour, C.; Jaouen, C.; Marchal, G.; Pacaud, J.; Grilhe, J.; Jousset, J.C.

    1997-01-01

    M{umlt o}ssbauer spectroscopy ({sup 57}Fe) shows evidence for mixing effects induced by electronic energy deposition in nanoscale Fe/Si multilayers irradiated with swift heavy ions. A decrease in the mixing efficiency with electronic stopping power is reported; a threshold is found, under which iron environment modifications no longer occur. The kinetics of Fe{endash}Si phase formation after irradiation suggests the existence of three regimes: (i) for high excitation levels, a magnetic amorphous phase is formed directly in the wake of the incoming ion and an almost complete mixing is reached at low fluence (10{sup 13} U/cm{sup 2}); (ii) for low excitation levels, a paramagnetic Si-rich amorphous phase is favored at the interface while crystalline iron subsists at high fluences; (iii) for intermediate excitation levels, saturation effects are observed and the formation rate of both magnetic and paramagnetic phases points to direct mixing in the ion wake but with a reduced track length in comparison to U irradiation. The measured interfacial mixing cross section induced by electronic energy deposition suggests that a thermal diffusion process is mainly involved in addition to damage creation. {copyright} {ital 1997 American Institute of Physics.}

  9. Fabrication of nanostructured transmissive optical devices on ITO-glass with UV1116 photoresist using high-energy electron beam lithography.

    PubMed

    Williams, Calum; Bartholomew, Richard; Rughoobur, Girish; Gordon, George S D; Flewitt, Andrew J; Wilkinson, Timothy D

    2016-12-02

    High-energy electron beam lithography for patterning nanostructures on insulating substrates can be challenging. For high resolution, conventional resists require large exposure doses and for reasonable throughput, using typical beam currents leads to charge dissipation problems. Here, we use UV1116 photoresist (Dow Chemical Company), designed for photolithographic technologies, with a relatively low area dose at a standard operating current (80 kV, 40-50 μC cm(-2), 1 nAs(-1)) to pattern over large areas on commercially coated ITO-glass cover slips. The minimum linewidth fabricated was ∼33 nm with 80 nm spacing; for isolated structures, ∼45 nm structural width with 50 nm separation. Due to the low beam dose, and nA current, throughput is high. This work highlights the use of UV1116 photoresist as an alternative to conventional e-beam resists on insulating substrates. To evaluate suitability, we fabricate a range of transmissive optical devices, that could find application for customized wire-grid polarisers and spectral filters for imaging, which operate based on the excitation of surface plasmon polaritons in nanosized geometries, with arrays encompassing areas ∼0.25 cm(2).

  10. Fabrication of nanostructured transmissive optical devices on ITO-glass with UV1116 photoresist using high-energy electron beam lithography

    NASA Astrophysics Data System (ADS)

    Williams, Calum; Bartholomew, Richard; Rughoobur, Girish; Gordon, George S. D.; Flewitt, Andrew J.; Wilkinson, Timothy D.

    2016-12-01

    High-energy electron beam lithography for patterning nanostructures on insulating substrates can be challenging. For high resolution, conventional resists require large exposure doses and for reasonable throughput, using typical beam currents leads to charge dissipation problems. Here, we use UV1116 photoresist (Dow Chemical Company), designed for photolithographic technologies, with a relatively low area dose at a standard operating current (80 kV, 40-50 μC cm-2, 1 nAs-1) to pattern over large areas on commercially coated ITO-glass cover slips. The minimum linewidth fabricated was ˜33 nm with 80 nm spacing; for isolated structures, ˜45 nm structural width with 50 nm separation. Due to the low beam dose, and nA current, throughput is high. This work highlights the use of UV1116 photoresist as an alternative to conventional e-beam resists on insulating substrates. To evaluate suitability, we fabricate a range of transmissive optical devices, that could find application for customized wire-grid polarisers and spectral filters for imaging, which operate based on the excitation of surface plasmon polaritons in nanosized geometries, with arrays encompassing areas ˜0.25 cm2.

  11. Adjusting an electron beam for drilling

    NASA Technical Reports Server (NTRS)

    Childress, C. L.

    1980-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  13. 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.

  14. Statistical process control for electron beam monitoring.

    PubMed

    López-Tarjuelo, Juan; Luquero-Llopis, Naika; García-Mollá, Rafael; Quirós-Higueras, Juan David; Bouché-Babiloni, Ana; Juan-Senabre, Xavier Jordi; de Marco-Blancas, Noelia; Ferrer-Albiach, Carlos; Santos-Serra, Agustín

    2015-07-01

    To assess the electron beam monitoring statistical process control (SPC) in linear accelerator (linac) daily quality control. We present a long-term record of our measurements and evaluate which SPC-led conditions are feasible for maintaining control. We retrieved our linac beam calibration, symmetry, and flatness daily records for all electron beam energies from January 2008 to December 2013, and retrospectively studied how SPC could have been applied and which of its features could be used in the future. A set of adjustment interventions designed to maintain these parameters under control was also simulated. All phase I data was under control. The dose plots were characterized by rising trends followed by steep drops caused by our attempts to re-center the linac beam calibration. Where flatness and symmetry trends were detected they were less-well defined. The process capability ratios ranged from 1.6 to 9.3 at a 2% specification level. Simulated interventions ranged from 2% to 34% of the total number of measurement sessions. We also noted that if prospective SPC had been applied it would have met quality control specifications. SPC can be used to assess the inherent variability of our electron beam monitoring system. It can also indicate whether a process is capable of maintaining electron parameters under control with respect to established specifications by using a daily checking device, but this is not practical unless a method to establish direct feedback from the device to the linac can be devised. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  15. Note on polarization of electron beam.

    SciTech Connect

    Yang, Z. J.; Energy Technology

    1997-01-01

    Based on the classical theory of electrodynamics, we show the feasibility of using superconductors to realize transversal and longitudinal polarizations of electron beams. The results can in principle be used with beams of positron and/or other particles with magnetic moments without major modifications. We briefly discuss applications of polarized electron beams in physical sciences and technology.

  16. 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.

  17. 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.

  18. Definition of Beam Diameter for Electron Beam Welding

    SciTech Connect

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

    2016-03-11

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

  19. Intense low energy positron beams

    SciTech Connect

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  20. Analysis of the electron-beam radiation damage of TEM samples in the acceleration energy range from 0.1 to 2 MeV using the standard theory for fast electrons

    NASA Astrophysics Data System (ADS)

    Reyes-Gasga, J.; García-García, R.

    2002-08-01

    The electron-beam-sample interaction is analyzed using the standard theory for fast electrons in the accelerating energy range from 0.1 to 2 MeV when the sample to be observed with TEM is composed of different atoms. This theory allows taking into account the contribution of the nearest neighbors of the target atoms, which is a more real approximation. For direct interaction the normal expressions are obtained, but for the cascade phenomenon a better approximation is presented. This theory is applied to the analysis of the experimentally reported electron-beam-induced structure modification in the superconductor YBa 2Cu 3O 7- x, the quasicrystalline alloy Al 62Cu 20Co 15Si 3, and the tooth enamel hydroxyapatite.

  1. Improvement of mechanical and thermal properties of high energy electron beam irradiated HDPE/hydroxyapatite nano-composite

    NASA Astrophysics Data System (ADS)

    Mohammadi, M.; Ziaie, F.; Majdabadi, A.; Akhavan, A.; Shafaei, M.

    2017-01-01

    In this research work, the nano-composites of high density polyethylene/hydroxyapatite samples were manufactured via two methods: In the first method, the granules of high density polyethylene and nano-structure hydroxyapatite were processed in an internal mixer to prepare the nano-composite samples with a different weight percentage of the reinforcement phase. As for the second one, high density polyethylene was prepared in nano-powder form in boiling xylene. During this procedure, the hydroxyapatite nano-powder was added with different weight percentages to the solvent to obtain the nano-composite. In both of the procedures, the used hydroxyapatite nano-powder was synthesized via hydrolysis methods. The samples were irradiated under 10 MeV electron beam in 70-200 kGy of doses. Mechanical, thermal and morphological properties of the samples were investigated and compared. The results demonstrate that the nano-composites which we have prepared using nano-polyethylene, show better mechanical and thermal properties than the composites prepared from normal polyethylene granules, due to the better dispersion of nano-particles in the polymer matrix.

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

    SciTech Connect

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

    2016-03-07

    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.

  5. 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.

  6. 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.

  7. Passive and active plasma deceleration for the compact disposal of electron beams

    SciTech Connect

    Bonatto, A.; Schroeder, C. B.; Vay, J.-L.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2015-08-15

    Plasma-based decelerating schemes are investigated as compact alternatives for the disposal of high-energy beams (beam dumps). Analytical solutions for the energy loss of electron beams propagating in passive and active (laser-driven) schemes are derived. These solutions, along with numerical modeling, are used to investigate the evolution of the electron distribution, including energy chirp and total beam energy. In the active beam dump scheme, a laser-driver allows a more homogeneous beam energy extraction and drastically reduces the energy chirp observed in the passive scheme. These concepts could benefit applications requiring overall compactness, such as transportable light sources, or facilities operating at high beam power.

  8. Passive and active plasma deceleration for the compact disposal of electron beams

    NASA Astrophysics Data System (ADS)

    Bonatto, A.; Schroeder, C. B.; Vay, J.-L.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2015-08-01

    Plasma-based decelerating schemes are investigated as compact alternatives for the disposal of high-energy beams (beam dumps). Analytical solutions for the energy loss of electron beams propagating in passive and active (laser-driven) schemes are derived. These solutions, along with numerical modeling, are used to investigate the evolution of the electron distribution, including energy chirp and total beam energy. In the active beam dump scheme, a laser-driver allows a more homogeneous beam energy extraction and drastically reduces the energy chirp observed in the passive scheme. These concepts could benefit applications requiring overall compactness, such as transportable light sources, or facilities operating at high beam power.

  9. Dense plasma heating by crossing relativistic electron beams

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  10. Dense plasma heating by crossing relativistic electron beams.

    PubMed

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

    2017-01-01

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

  11. 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.

  12. SU-E-T-632: Preliminary Study On Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculations

    SciTech Connect

    Jin, L; Eldib, A; Li, J; Price, R; Ma, C

    2015-06-15

    Purpose: Uneven nose surfaces and air cavities underneath and the use of bolus present complexity and dose uncertainty when using a single electron energy beam to plan treatments of nose skin with a pencil beam-based planning system. This work demonstrates more accurate dose calculation and more optimal planning using energy and intensity modulated electron radiotherapy (MERT) delivered with a pMLC. Methods: An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reduce the scatter-caused penumbra, a short SSD (61 cm) was used. Our previous work demonstrates good agreement in percentage depth dose and off-axis dose between calculations and film measurement for various field sizes. A MERT plan was generated for treating the nose skin using a patient geometry and a dose volume histogram (DVH) was obtained. The work also shows the comparison of 2D dose distributions between a clinically used conventional single electron energy plan and the MERT plan. Results: The MERT plan resulted in improved target dose coverage as compared to the conventional plan, which demonstrated a target dose deficit at the field edge. The conventional plan showed higher dose normal tissue irradiation underneath the nose skin while the MERT plan resulted in improved conformity and thus reduces normal tissue dose. Conclusion: This preliminary work illustrates that MC-based MERT planning is a promising technique in treating nose skin, not only providing more accurate dose calculation, but also offering an improved target dose coverage and conformity. In addition, this technique may eliminate the necessity of bolus, which often produces dose delivery uncertainty due to the air gaps that may exist between the bolus and skin.

  13. 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.

  14. 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.

  15. Optical constants of electron-beam evaporated boron films in the 6.8-900 eV photon energy range.

    PubMed

    Fernández-Perea, Mónica; Larruquert, Juan I; Aznárez, José A; Méndez, José A; Vidal-Dasilva, Manuela; Gullikson, Eric; Aquila, Andy; Soufli, Regina; Fierro, J L G

    2007-12-01

    The optical constants of electron-beam evaporated boron from 6.8 to 900 eV were calculated through transmittance measurements of boron thin films deposited onto carbon-coated microgrids or LiF substrates in ultrahigh-vacuum conditions. In the low-energy part of the spectrum the measurements were performed in situ on freshly deposited samples, whereas in the high-energy range the samples were exposed to the atmosphere before the measurements. The extinction coefficient was calculated directly from the transmittance data, and a Kramers-Kronig analysis that combined the current data with data from the literature was performed to determine the dispersive part of the index of refraction. Finally, two different sum-rule tests were performed that indicated the good consistency of the data.

  16. Longitudinal Density Modulation and Energy Conversion in Intense Beams

    SciTech Connect

    Harris, J; Neumann, J; Tian, K; O'Shea, P

    2006-02-17

    Density modulation of charged particle beams may occur as a consequence of deliberate action, or may occur inadvertently because of imperfections in the particle source or acceleration method. In the case of intense beams, where space charge and external focusing govern the beam dynamics, density modulation may under some circumstances be converted to velocity modulation, with a corresponding conversion of potential energy to kinetic energy. Whether this will occur depends on the properties of the beam and the initial modulation. This paper describes the evolution of discrete and continuous density modulations on intense beams, and discusses three recent experiments related to the dynamics of density-modulated electron beams.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Bakeman, Michael S.

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

  19. Synthesis of polymer materials by low energy electron beam. IV. EB-polymerized urethane-acrylate, -methacrylate and -acrylamide

    NASA Astrophysics Data System (ADS)

    Ando, Masayuki; Uryu, Toshiyuki

    The structure and properties before and after electron beam (EB) irradiation were investigated using urethane prepolymers with different terminal groups of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA) and N-hydroxymethyl acrylamide (HMAAm). The prepolymers were synthesized by reaction of HEA, HEMA and HMAAm with the isocyanate-capped intermediate, which was obtained by reaction of poly(butylene adipate)diol (PBAD) with 4,4'-diphenylmethane diisocyanate. The resulting urethane-acrylate (UA-251M), -methacrylate (UMA-251M) and -acrylamide (UNAA-251M) had the crystallinity arising from PBAD moieties, and UA-251M and UMA-251M had higher crystallinity than UNAA-251M. IR results indicated that UNAA-251M was larger in the fraction of free NH stretching absorption than UA-251M and UMA-251M regardless of the number of NH group per a molecule. Accordingly, it was assumed that the difference in crystallinity was attributed to the polarity of terminal group. Hence, the rate of gel formation for UA-251M and UMA-251M was higher than that of UNAA-251M. The crystallinity based on PBAD of the prepolymers was remained also after EB irradiation. Spherulitic texture was observed on the EB-polymerized gel film surfaces for UA-251M and UMA-251M, while it was almost destroyed for UNAA-251M. Mechanical properties of UA-251M and UMA-251M gel films were much superior to those of UNAA-251M gel film according to the phase structure. Especially, UMA-251M gel film represented most excellent mechanical properties. Schematic models of the phase structure for UA-251M, UMA-251M and UNAA-251M were suggested from all experimental results.

  20. On the possibility of generating low-energy positrons on accelerators of electrons with a beam energy of a few MeV and on terawatt lasers

    NASA Astrophysics Data System (ADS)

    Gorlova, D. A.; Nedorezov, V. G.; Ivanov, K. A.; Savel'ev, A. B.; Turinge, A. A.; Tsymbalov, I. N.

    2017-06-01

    Based on the numerical simulations, we estimate the possibility of generating positrons by low-energy electrons (below 10 MeV) produced by electron accelerators and femtosecond lasers. A review of experimental work reported in the literature is presented. The simulation is carried out using the GEANT-4 software package for the particular conditions of a possible experiment at the terawatt femtosecond laser facility of the International Laser Centre at the Moscow State University and the LUE-8 MeV linear electron accelerator at the Institute for Nuclear Research, Russian Academy of Sciences.

  1. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  2. The use of electron beam in RIA R&D

    NASA Astrophysics Data System (ADS)

    Gomes, Itacil C.; Nolen, Jerry; Reed, Claude

    2004-12-01

    This paper discusses two electron beam applications for the RIA (Rare Isotope Accelerator) R&D. The first is for simulating energy deposition of heavy ions on lithium jets. The peak energy deposition for a 400-kW uranium beam will be 4 MW/cm 3. Calculations have shown that a 1-MeV electron beam with 40mA of current has a peak energy deposition about 4 MW/cm 3 making it suitable to mimic the thermal response of lithium jet at that uranium beam heat load. The second application of electron beams for RIA R&D, discussed in this paper, is the use of low energy electron beam as a diagnosis tool for on-line monitoring of thickness variations of thin foils or thin jets. Thin foils can be corroded and jets might experience instabilities that can compromise their functionality. Low energy electron beams can be used to detect any change in thickness enabling a continuous on-line monitoring of the thin film being monitored. Calculations have indicated that variations in lithium jet thicknesses at the micron level can easily be detected.

  3. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB

    SciTech Connect

    Ren, Haitao Pozdeyev, Eduard; Lund, Steven M.; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-15

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  4. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB

    NASA Astrophysics Data System (ADS)

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M.; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  5. SU-E-T-274: Radiation Therapy with Very High-Energy Electron (VHEE) Beams in the Presence of Metal Implants

    SciTech Connect

    Jensen, C; Palma, B; Qu, B; Maxim, P; Loo, B; Bazalova, M; Hardemark, B; Hynning, E

    2014-06-01

    Purpose: To evaluate the effect of metal implants on treatment plans for radiation therapy with very high-energy electron (VHEE) beams. Methods: The DOSXYZnrc/BEAMnrc Monte Carlo (MC) codes were used to simulate 50–150MeV VHEE beam dose deposition and its effects on steel and titanium (Ti) heterogeneities in a water phantom. Heterogeneities of thicknesses ranging from 0.5cm to 2cm were placed at 10cm depth. MC was also used to calculate electron and photon spectra generated by the VHEE beams' interaction with metal heterogeneities. The original VMAT patient dose calculation was planned in Eclipse. Patient dose calculations with MC-generated beamlets were planned using a Matlab GUI and research version of RayStation. VHEE MC treatment planning was performed on water-only geometry and water with segmented prostheses (steel and Ti) geometries with 100MeV and 150MeV beams. Results: 100MeV PDD 5cm behind steel/Ti heterogeneity was 51% less than in the water-only phantom. For some cases, dose enhancement lateral to the borders of the phantom increased the dose by up to 22% in steel and 18% in Ti heterogeneities. The dose immediately behind steel heterogeneity decreased by an average of 6%, although for 150MeV, the steel heterogeneity created a 23% increase in dose directly behind it. The average dose immediately behind Ti heterogeneities increased 10%. The prostate VHEE plans resulted in mean dose decrease to the bowel (20%), bladder (7%), and the urethra (5%) compared to the 15MV VMAT plan. The average dose to the body with prosthetic implants was 5% higher than to the body without implants. Conclusion: Based on MC simulations, metallic implants introduce dose perturbations to VHEE beams from lateral scatter and backscatter. However, when performing clinical planning on a prostate case, the use of multiple beams and inverse planning still produces VHEE plans that are dosimetrically superior to photon VMAT plans. BW Loo and P Maxim received research support from Ray

  6. Creating electron vortex beams with light.

    PubMed

    Handali, Jonathan; Shakya, Pratistha; Barwick, Brett

    2015-02-23

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

  7. 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.

  8. The POSEIDON electron beam generator. Final report

    SciTech Connect

    Sethian, J.D.; Mora, F.

    1982-09-27

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

  9. SU-D-19A-06: The Effect of Beam Parameters On Very High-Energy Electron Radiotherapy: A Planning Study

    SciTech Connect

    Palma, B; Bazalova, M; Qu, B; Loo, B; Maxim, P; Hardemark, B; Hynning, E

    2014-06-01

    Purpose: We evaluated the effect of very high-energy electron (VHEE) beam parameters on the planning of a lung cancer case by means of Monte Carlo simulations. Methods: We simulated VHEE radiotherapy plans using the EGSnrc/BEAMnrc-DOSXYZnrc code. We selected a lung cancer case that was treated with 6MV photon VMAT to be planned with VHEE. We studied the effect of beam energy (80 MeV, 100 MeV, and 120 MeV), number of equidistant beams (16 or 32), and beamlets sizes (3 mm, 5 mm or 7 mm) on PTV coverage, sparing of organs at risk (OARs) and dose conformity. Inverse-planning optimization was performed in a research version of RayStation (RaySearch Laboratories AB) using identical objective functions and constraints for all VHEE plans. Results: Similar PTV coverage and dose conformity was achieved by all the VHEE plans. The 100 MeV and 120 MeV VHEE plans were equivalent amongst them and were superior to the 80 MeV plan in terms of OARs sparing. The effect of using 16 or 32 equidistant beams was a mean difference in average dose of 2.4% (0%–7.7%) between the two plans. The use of 3 mm beamlet size systematically reduced the dose to all the OARs. Based on these results we selected the 100MeV-16beams-3mm-beamlet-size plan to compare it against VMAT. The selected VHEE plan was more conformal than VMAT and improved OAR sparing (heart and trachea received 125% and 177% lower dose, respectively) especially in the low-dose region. Conclusion: We determined the VHEE beam parameters that maximized the OAR dose sparing and dose conformity of the actually delivered VMAT plan of a lung cancer case. The selected parameters could be used for the planning of other treatment sites with similar size, shape, and location. For larger targets, a larger beamlet size might be used without significantly increasing the dose. B Palma: None. M Bazalova: None. B Hardemark: Employee, RaySearch Americas. E Hynning: Employee, RaySearch Americas. B Qu: None. B Loo Jr.: Research support, Ray

  10. Hydrophobicity of electron beam modified surface of hydroxyapatite films

    NASA Astrophysics Data System (ADS)

    Gregor, M.; Plecenik, T.; Tofail, S. A. M.; Zahoran, M.; Truchly, M.; Vargova, M.; Laffir, F.; Plesch, G.; Kus, P.; Plecenik, A.

    2015-05-01

    Arrays of micron-sized domains of modified surface potential were created on hydroxyapatite films by mid-energy (20 keV) electron beam irradiation available in a laboratory scanning electron microscope. The dosage of electron beam was varied between 10-3 and 103 μC/cm2 to inject charge into the film surface. Contrary to the conventional electrowetting theory, the dosage of injected charge used in creating such microdomains caused a gradual increase of the water contact angle from 57° to 93° due to the elimination of the polar component of the surface free energy. Surface contamination by carbonaceous species can be held only partially responsible for such behavior at lower dosage of electron beam. A transfer of free surface charge to water and an electron beam induced disruption of polar orientation of OH ions have been attributed to be influencial factors in the overall dewetting behavior.

  11. Isotope separation using tuned laser and electron beam