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Sample records for cathode rf gun

  1. Laser photo-cathode RF-gun

    International Nuclear Information System (INIS)

    Washio, Masakazu

    2006-01-01

    High quality beam generation project based on High-Tech Research Center Project, which has been approved by Ministry of Education, Culture, Sports, Science and Technology in 1999, has been conducted by advanced research institute for science and engineering, Waseda University. In the project, laser photo-cathode RF-gun has been selected for the high quality electron beam source. RF cavities with low dark current, which were made by diamond turning technique have been successfully manufactured. The low emittance electron beam was realized by choosing the modified laser injection technique. The obtained normalized emittance was about 3 mm mrad at 100 pC of electron charge. The soft X-ray beam generation with the energy of 370 eV, which is in the energy region of so-called 'water window', by inverse Compton scattering has been performed by the collision between IR laser and the low emittance electron beams. (author)

  2. Rf Gun with High-Current Density Field Emission Cathode

    International Nuclear Information System (INIS)

    Jay L. Hirshfield

    2005-01-01

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  3. Surface Characterization of the LCLS RF Gun Cathode

    International Nuclear Information System (INIS)

    Brachmann, Axel; Decker, Franz-Josef; Ding, Yuantao; Dowell, David; Emma, Paul; Frisch, Josef; Gilevich, Sasha; Hays, Gregory; Hering, Philippe; Huang, Zhirong; Iverson, Richard; Loos, Henrik; Miahnahri, Alan; Nordlund, Dennis; Nuhn, Heinz-Dieter; Pianetta, Piero; Turner, James; Welch, James; White, William; Wu, Juhao; Xiang, Dao

    2012-01-01

    The first copper cathode installed in the LCLS RF gun was used during LCLS commissioning for more than a year. However, after high charge operation (> 500 pC), the cathode showed a decline of quantum efficiency within the area of drive laser illumination. They report results of SEM, XPS and XAS studies that were carried out on this cathode after it was removed from the gun. X-ray absorption and X-ray photoelectron spectroscopy reveal surface contamination by various hydrocarbon compounds. In addition they report on the performance of the second installed cathode with emphasis on the spatial distribution of electron emission.

  4. X-Band Thermionic Cathode RF Gun at UTNL

    CERN Document Server

    Fukasawa, Atsushi; Dobashi, Katsuhiro; Ebina, Futaro; Hayano, Hitoshi; Higo, Toshiyasu; Kaneyasu, Tatsuo; Matsuo, Kennichi; Ogino, Haruyuki; Sakae, Hisaharu; Sakamoto, Fumito; Uesaka, Mitsuru; Urakawa, Junji

    2005-01-01

    The X-band (11.424 GHz) linac for compact Compton scattering hard X-ray source are under construction at Nuclear Engineering Research Laboratory, University of Tokyo. This linac designed to accelerate up to 35 MeV, and this electron beam will be used to produce hard X-ray by colliding with laser. It consists of a thermionic cathode RF gun, an alpha magnet, and a traveling wave tube. The gun has 3.5 cells (unloaded Q is 8250) and will be operated at pi-mode. A dispenser cathode is introduced. Since the energy spread of the beam from the gun is predicted to be broad due to the continuous emission from the thermionic cathode, a slit is placed in the alpha magnet to eliminate low energy electrons. The simulation on the injector shows the beam energy 2.9 MeV, the charge 23 pC/bunch, and the emittance less than 10 mm.mrad. The experiment on the gun is planed in the beginning of 2005, and the details will be discussed on the spot.

  5. Study of Control Grid Thermionic Cathode RF Gun

    CERN Document Server

    Xiao, Jin; Ming, Li; Xinfan, Yang; Xumin, Shen; Yanan, Chen; Zhou, Xu

    2004-01-01

    In this paper, the beam loading effect of RF Gun was analyzed. To minimize the energy spread, the grid control RF Gun was introduced. The result shows that the grid congrol RF Gun can increase electron beam within 1% energy spread.

  6. Initial test of an rf gun with a GaAs cathode installed

    International Nuclear Information System (INIS)

    Aulenbacher, K.; Bossart, R.; Braun, H.

    1996-09-01

    The operation of an rf gun with a GaAs crystal installed as the cathode has been tested in anticipation of eventually producing a polarized electron beam for a future e + /e - collider using an rf photoinjector

  7. Formation of a high quality electron beam using photo cathode RF electron gun

    International Nuclear Information System (INIS)

    Washio, Masakazu

    2000-01-01

    Formation of a high quality electron beam using photo cathode RF electron gun is expected for formation of a next generation high brilliant X-ray beam and a source for electron and positron collider. And, on a field of material science, as is possible to carry out an experiment under ultra short pulse and extremely high precision in time, it collects large expectation. Recently, formation of high quality beam possible to develop for multi directions and to use by everyone in future has been able to realize. Here were explained on electron beam source, principle and component on RF electron gun, working features on RF gun, features and simulation of RF gun under operation, and some views in near future. (G.K.)

  8. Current transmission and nonlinear effects in un-gated thermionic cathode RF guns

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Harris, J. R. [Air Force Weapons Lab

    2017-05-03

    Un-gated thermionic cathode RF guns are well known as a robust source of electrons for many accelerator applications. These sources are in principle scalable to high currents without degradation of the transverse emittance due to control grids but they are also known for being limited by back-bombardment. While back-bombardment presents a significant limitation, there is still a lack of general understanding on how emission over the whole RF period will affect the nature of the beams produced from these guns. In order to improve our understanding of how these guns can be used in general we develop analytical models that predict the transmission efficiency as a function of the design parameters, study how bunch compression and emission enhancement caused by Schottky barrier lowering affect the output current profile in the gun, and study the onset of space-charge limited effects and the resultant virtual cathode formation leading to a modulation in the output current distribution.

  9. OBSERVATION OF REPETITION-RATE DEPENDANT EMISSION FROM AN UN-GATED THERMIONIC CATHODE RF GUN

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Sun, Y. [Argonne; Harris, J. R. [AFRL, NM; Lewellen, J. W. [Los Alamos Natl. Lab.

    2016-09-28

    Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an ungated thermionic cathode RF gun to high average current machines.

  10. Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P.; Sun, Y.; Harris, J.R.; Lewellen, J.W.

    2017-06-02

    Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an ungated thermionic cathode RF gun to high average current.

  11. Analysis of emittance compensation and simulation results to photo-cathode RF gun

    CERN Document Server

    LiuShengGuang

    2002-01-01

    The emittance compensation technology will be used on the photo-cathode RF gun for Shanghai SDUV-FEL. The space charge force and its effect on electron beam transverse emittance in RF gun is studied, the principle of emittance compensation in phase-space is discussed. The authors have designed a compensation solenoid and calculated its magnetic field distribution. Its performance has been studied by the code PARMELA. A simulation result indicates that the normalized transverse RMS emittance for electron beam of 1.5 nC is 1.612 pi mm centre dot mrad, electron energy E = 5.71 MeV

  12. Reducing Back-Bombardment Effect Using Thermionic Cathode in IAE RF Gun

    CERN Document Server

    Kii, Toshiteru; Masuda, Kai; Murakami, Shio; Ohgaki, Hideaki; Yamazaki, Tetsuo; Yoshikawa, Kiyoshi; Zen, Heishun

    2004-01-01

    We have numerically studied on improvement of electron beam macro-pulse properties from thermionic RF gun [1,2]. Beam properties, such as energy spectrum, macro-pulse duration and emittance were measured with a 2 mm diameter slim thermionic dispenser cathode. Effect of the transverse magnetic field to reduce back-streaming electrons to these properties was studied experimentally. Comparison with measured and numerical results will be discussed. Effect of a non-flat RF input to compensate a decreasing beam energy during macropulse due to a back-bombardment effect will be also presented.

  13. ANALYTICAL MODELING OF ELECTRON BACK-BOMBARDMENT INDUCED CURRENT INCREASE IN UN-GATED THERMIONIC CATHODE RF GUNS

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Sun, Y. [Argonne; Harris, J. R. [AFRL, NM; Lewellen, J. W. [Los Alamos Natl. Lab.

    2016-09-28

    In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, fieldenhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

  14. Ion tracking in photocathode rf guns

    Directory of Open Access Journals (Sweden)

    John W. Lewellen

    2002-02-01

    Full Text Available Projected next-generation linac-based light sources, such as PERL or the TESLA free-electron laser, generally assume, as essential components of their injector complexes, long-pulse photocathode rf electron guns. These guns, due to their design rf pulse durations of many milliseconds to continuous wave, may be more susceptible to ion bombardment damage of their cathodes than conventional rf guns, which typically use rf pulses of microsecond duration. This paper explores this possibility in terms of ion propagation within the gun, and presents a basis for future study of the subject.

  15. Operation of the APS rf gun

    International Nuclear Information System (INIS)

    Lewellen, J. W.

    1998-01-01

    The Advanced Photon Source (APS) has a thermionic-cathode rf gun system capable of providing beam to the APS linac. The gun system consists of a 1.6-cell thermionic-cathode rf gun, a fast kicker for beam current control, and an alpha magnet for bunch compression and injection into the APS linac line. This system is intended for use both as an injector for positron creation, and as a first beam source for the Low-Energy Undulator Test Line (LEUTL) project [1]. The first measured performance characteristics of the gun are presented.

  16. Lasers for RF guns: Proceedings

    International Nuclear Information System (INIS)

    Srinivasan-Rao, T.

    1994-01-01

    In the past decade, laser driven RF guns have matured from a device under development to a proven source for high brightness and low emittance electron beams. The reliability of the electron beam from these sources is dictated by the laser system that drives it. In addition, capabilities of the laser systems play a vital role in the design of the electron source for future machines such as the TESLA and NLC. The purpose of this workshop was to provide a forum for discussing the design criteria for the laser systems so that the reliability of the existing sources could be improved and the future machines could be serviced. The Workshop brought together experts in RF Guns, accelerators, and lasers, from both the commercial and academic community. Most of the presentations, discussions and conclusions at the workshop are included in these proceedings. The contents are divided into three sections, Section I contains the invited talks that outline the requirements of the RF Guns and the capabilities of the laser systems to meet these requirements. Section II includes most of the papers presented in the poster session. These papers describe various laser systems used with electron guns, schemes to modify the laser beam profile to optimize the electron bunch, and computer simulations of electron trajectories. Section III contains the summaries of the working groups. As the summary section indicates, with sufficient feed back systems, the electron gun could be made to operate reliably with minimum downtime, using commercial lasers currently available. The design of laser systems for future colliders depend critically on the choice of the cathode m the gun and its efficiency. Tentative designs of laser systems for the TESLA test facility and LCLS had been drawn assuming a copper cathode. Using a more efficient cathode will ease the energy requirement of the laser and simplify the design. The individual papers have been cataloged separately elsewhere

  17. X-Band RF Gun Development

    International Nuclear Information System (INIS)

    Vlieks, A.E.

    2012-01-01

    In support of the MEGa-ray program at LLNL and the High Gradient research program at SLAC, a new X-band multi-cell RF gun is being developed. This gun, similar to earlier guns developed at SLAC for Compton X-ray source program, will be a standing wave structure made of 5.5 cells operating in the pi mode with copper cathode. This gun was designed following criteria used to build SLAC X-band high gradient accelerating structures. It is anticipated that this gun will operate with surface electric fields on the cathode of 200 MeV/m with low breakdown rate. RF will be coupled into the structure through a final cell with symmetric duel feeds and with a shape optimized to minimize quadrupole field components. In addition, geometry changes to the original gun, operated with Compton X-ray source, will include a wider RF mode separation, reduced surface electric and magnetic fields.

  18. Performance of the Brookhaven photocathode rf gun

    International Nuclear Information System (INIS)

    Batchelor, K.; Ben-Zvi, I.; Fernow, R.C.; Fischer, J.; Fisher, A.S.; Gallardo, J.; Ingold, G.; Kirk, H.G.; Leung, K.P.; Malone, R.; Pogorelsky, I.; Srinivasan-Rao, T.; Rogers, J.; Tsang, T.; Sheehan, J.; Ulc, S.; Woodle, M.; Xie, J.; Zhang, R.S.; Lin, L.Y.; McDonald, K.T.; Russell, D.P.; Hung, C.M.; Wang, X.J.

    1991-01-01

    The Brookhaven Accelerator Test Facility (ATF) uses a photocathode rf gun to provide a high-brightness electron beam intended for FEL and laser-acceleration experiments. The rf gun consists of 1 1/2 cells driven at 2856 MHz in π-mode with a maximum cathode field of 100 MV/m. To achieve long lifetimes, the photocathode development concentrates on robust metals such as copper, yttrium and samarium. We illuminate these cathodes with a 10-ps, frequency-quadrupled Nd:YAG laser. We describe the initial operation of the gun, including measurements of transverse and longitudinal emittance, quantum efficiencies, and peak current. The results are compared to models

  19. RF Processing Experience with the GTF Prototype RF Gun

    International Nuclear Information System (INIS)

    Schmerge, J.F.

    2010-01-01

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. A total of five different metal cathodes (4 Cu and 1 Mg) have been installed on the GTF gun. The rf processing history with the different cathodes will be presented including peak field achieved at the cathode. The LCLS gun is intended to operate at 120 MV/m and fields up to 140 MV/m have been achieved in the GTF gun. After installing a new cathode the number of rf pulses required to reach 120 MV/m is approximately 5-10 million. Total emitted dark current and Fowler Nordheim plots are also shown over the life of the cathode. The GTF photo-injector gun is an S-band standing-wave structure, with two resonant cavities and an intervening thick washer (Figure 1). The flat, back wall of the first cavity is a copper plate that serves as photocathode when illuminated with ultraviolet light from a pulsed, high-power laser. RF power enters the gun through an iris on the outer wall of the second cavity, and is coupled to the first through the axial opening of the washer. The first cavity is often referred to as a half cell, because its full-cell length has been truncated by the cathode plate and the second cavity is called the full cell. The gun is designed to operate in a π mode, with the peak field on axis in each cell approximately equal. The maximum in the half cell occurs at the cathode, and in the full cell near the center of the cavity. The field profile and tuning procedures are discussed in a separate tech note (1).

  20. Unbalanced field RF electron gun

    Science.gov (United States)

    Hofler, Alicia

    2013-11-12

    A design for an RF electron gun having a gun cavity utilizing an unbalanced electric field arrangement. Essentially, the electric field in the first (partial) cell has higher field strength than the electric field in the second (full) cell of the electron gun. The accompanying method discloses the use of the unbalanced field arrangement in the operation of an RF electron gun in order to accelerate an electron beam.

  1. Photocathode operation of a thermionic RF gun

    International Nuclear Information System (INIS)

    Thorin, S.; Cutic, N.; Lindau, F.; Werin, S.; Curbis, F.

    2009-01-01

    The thermionic RF gun using a BaO cathode at the MAX-lab linac injector has been successfully commissioned for additional operation as a photocathode gun. By retaining the BaO cathode, lowering the temperature below thermal emission and illuminating it with a UV (263 nm) 9 ps laser pulse a reduced emittance and enhanced emission control has been achieved. Measurements show a normalised emittance of 5.5 mm mrad at 200 pC charge and a maximum quantum efficiency of 1.1x10 -4 . The gun is now routinely switched between storage ring injections in thermionic mode and providing a beam for the MAX-lab test FEL in photocathode mode.

  2. Method of electron emission control in RF guns

    International Nuclear Information System (INIS)

    Khodak, I.V.; Kushnir, V.A.

    2001-01-01

    The electron emission control method for a RF gun is considered.According to the main idea of the method,the additional resonance system is created in a cathode region where the RF field strength could be varied using the external pulse equipment. The additional resonance system is composed of a coaxial cavity coupled with a RF gun cylindrical cavity via an axial hole. Computed results of radiofrequency and electrodynamic performances of such a two-cavity system and results of the RF gun model pilot study are presented in. Results of particle dynamics simulation are described

  3. Method of electron emission control in RF guns

    CERN Document Server

    Khodak, I V

    2001-01-01

    The electron emission control method for a RF gun is considered.According to the main idea of the method,the additional resonance system is created in a cathode region where the RF field strength could be varied using the external pulse equipment. The additional resonance system is composed of a coaxial cavity coupled with a RF gun cylindrical cavity via an axial hole. Computed results of radiofrequency and electrodynamic performances of such a two-cavity system and results of the RF gun model pilot study are presented in. Results of particle dynamics simulation are described.

  4. The properties of on-axis coupled structure RF gun

    CERN Document Server

    Oda, F; Nakayama, A; Koike, H; Tanabe, E

    2000-01-01

    Kawasaki Heavy Industries Ltd. (KHI) has developed the compact IR FEL device, which adopts a combination of a newly designed RF gun with a thermionic cathode and an alpha-magnet as an injector. The accelerating mode of the S-band RF gun is a pi/2 standing wave mode. The coupling cell is located on the beam axis, the so-called on-axis coupled structure (OCS). The cavity shape was designed by using electromagnetic field analytical codes. The OCS RF gun was manufactured and the electromagnetic properties were measured. The results show good agreement with the simulations.

  5. Beam-Based Procedures for RF Guns

    CERN Document Server

    Krasilnikov, Mikhail; Grabosch, H J; Hartrott, Michael; Hui Han, Jang; Miltchev, Velizar; Oppelt, Anne; Petrosyan, Bagrat; Staykov, Lazar; Stephan, Frank

    2005-01-01

    A wide range of rf photo injector parameters has to be optimized in order to achieve an electron source performance as required for linac based high gain FELs. Some of the machine parameters can not be precisely controlled by direct measurements, whereas the tolerance on them is extremely tight. Therefore, this should be met with beam-based techniques. Procedures for beam-based alignment (BBA) of the laser on the photo cathode as well as solenoid alignment have been developed. They were applied at the Photo Injector Test facility at DESY Zeuthen (PITZ) and at the photo injector of the VUV-FEL at DESY Hamburg. A field balance of the accelerating mode in the 1 ½ cell gun cavity is one of the key beam dynamics issues of the rf gun. Since no direct field measurement in the half and full cell of the cavity is available for the PITZ gun, a beam-based technique to determine the field balance has been proposed. A beam-based rf phase monitoring procedure has been developed as well.

  6. Testing a GaAs cathode in SRF gun

    International Nuclear Information System (INIS)

    Wang, E.; Kewisch, J.; Ben-Zvi, I.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

    2011-01-01

    RF electron guns with a strained superlattice GaAs cathode are expected to generate polarized electron beams of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface and lower cathode temperature. We plan to install a bulk GaAs:Cs in a SRF gun to evaluate the performance of both the gun and the cathode in this environment. The status of this project is: In our 1.3 GHz 1/2 cell SRF gun, the vacuum can be maintained at nearly 10 -12 Torr because of cryo-pumping at 2K. With conventional activation of bulk GaAs, we obtained a QE of 10% at 532 nm, with lifetime of more than 3 days in the preparation chamber and have shown that it can survive in transport from the preparation chamber to the gun. The beam line has been assembled and we are exploring the best conditions for baking the cathode under vacuum. We report here the progress of our test of the GaAs cathode in the SRF gun. Future particle accelerators, such as eRHIC and the ILC require high-brightness, high-current polarized electrons. Strained superlattice GaAs:Cs has been shown to be an efficient cathode for producing polarized electrons. Activation of GaAs with Cs,O(F) lowers the electron affinity and makes it energetically possible for all the electrons, excited into the conduction band that drift or diffuse to the emission surface, to escape into the vacuum. Presently, all operating polarized electron sources, such as the CEBAF, are DC guns. In these devices, the excellent ultra-high vacuum extends the lifetime of the cathode. However, the low field gradient on the photocathode's emission surface of the DC guns limits the beam quality. The higher accelerating gradients, possible in the RF guns, generate a far better beam. Until recently, most RF guns operated at room temperature, limiting the vacuum to ∼10 -9 Torr. This destroys the GaAs's NEA surface. The SRF guns combine the excellent vacuum conditions of DC guns and the high accelerating

  7. RF gun using laser-triggered photocathode

    International Nuclear Information System (INIS)

    Akiyama, H.; Otake, Y.; Naito, T.; Takeuchi, Y.; Yoshioka, M.

    1992-01-01

    An RF gun using laser-triggered photocathode has many advantages as an injector of the linear colliders since it can generate a low emittance and high current pulsed beam. The experimental facility for the RF gun, such as an RF system, a laser system and a photocathode have been fabricated to study the fundamental characteristics. The dynamics of the RF gun has also studied by the 1D sheet beam model. (author)

  8. An rf modulated electron gun pulser for linacs

    International Nuclear Information System (INIS)

    Legg, R.; Hartline, R.

    1991-01-01

    Present linac injector designs often make use of sub-harmonic prebuncher cavities to properly bunch the electron beam before injection into a buncher and subsequent accelerating cavities. This paper proposes an rf modulated thermionic gun which would allow the sub-harmonic buncher to be eliminated from the injector. The performance parameters for the proposed gun are 120 kV operating voltage, macropulse duration-single pulse mode 2 nsec, multiple pulse mode 100 nsec, rf modularing frequency 500 MHz, charge per micropulse 0.4 nC, macropulse repetition frequency 10 Hz (max). The gun pulser uses a grid modulated planar triode to drive the gun cathode. The grid driver takes advantage of recently developed modular CATV rf drivers, high performance solid state pulser devices, and high-frequency fiber optic transmitters for telecommunications. Design details are presented with associated SPICE runs simulating operation of the gun

  9. A NEW THERMIONIC RF ELECTRON GUN FOR SYNCHROTRON LIGHT SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Kutsaev, Sergey; Agustsson, R.; Hartzell, J; Murokh, A.; Nassiri, A.; Savin, E.; Smirnov, A.V.; Smirnov, A. Yu; Sun, Y.; Verma, A; Waldschmidt, Geoff; Zholents, A.

    2017-06-02

    A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source at Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity and report the progress towards high power tests of the cathode assembly of the new gun.

  10. Investigation of the Stability of the RF Gun of the SSRL Injector System

    International Nuclear Information System (INIS)

    Moore, J

    2004-01-01

    In the previous three years, Stanford Synchrotron Radiation Laboratory (SSRL) has experienced electron beam instabilities in the injector system of the Stanford Positron Electron Asymmetric Ring (SPEAR). Currently, for approximately the past four months the radio frequency (RF) gun of the linear accelerator injector system of the SPEAR at SSRL has become increasingly unstable. The current of the RF gun has become progressively sluggish and the lifetime of the cathode within the RF gun has been much shorter than expected. The cathode also sustains many unexplained damages. The instability of the RF gun affects the entire operation of SPEAR, creating substantial inconvenience. Through mechanical, design, and procedural analysis of the RF gun and the cathode that emits the electron beam of the linear accelerator, a solution to prolong the life of the cathode and secure the stability of the gun can be found. The thorough analysis of the gun and cathode involves investigation into the history of cathode installation and removal through the years of SPEAR operation as well as interviews with SSRL personnel involved with the upkeep of the gun and cathode. From speaking with SSRL employees and reviewing several articles many possible causes for beam instability were presented. The most likely cause of the SSRL gun instability is excessive back bombardment that can be attributed to running the cathode at too high a temperature

  11. Experimental and theoretical investigations of a 17 GHz RF gun

    CERN Document Server

    Brown, W J; Kreischer, K E; Pedrozzi, M; Shapiro, M A; Temkin, R J

    1999-01-01

    We report on experimental and theoretical investigations of a 17 GHz RF photocathode electron gun. This is the first photocathode electron gun to operate at a frequency above 2.856 GHz. The 1.5 cell, pi mode, copper cavity was tested with 50 ns pulses from a 17.150 GHz klystron amplifier built by Haimson Research Corp. A Bragg filter was used at the RF gun to reduce the reflection of parasitic modes back into the klystron. Coupling hole theory in conjunction with cold test measurements was used to determine the field profile in the RF gun. The particle in cell code MAGIC as well as coupled envelope equations were used to simulate the beam dynamics in the RF gun. With power levels of 4 MW, the on axis electric field at the cathode exceeds 300 MV/m, corresponding to an average accelerating gradient of 200 MV/m over the first half cell of the gun. Breakdown was observed at power levels above 5 MW. Electron bunches were produced by 20 mu J, 1 ps UV laser pulses impinging on the RF gun copper photocathode and were...

  12. Simulations of S-band RF gun with RF beam control

    Science.gov (United States)

    Barnyakov, A. M.; Levichev, A. E.; Maltseva, M. V.; Nikiforov, D. A.

    2017-08-01

    The RF gun with RF control is discussed. It is based on the RF triode and two kinds of the cavities. The first cavity is a coaxial cavity with cathode-grid assembly where beam bunches are formed, the second one is an accelerating cavity. The features of such a gun are the following: bunched and relativistic beams in the output of the injector, absence of the back bombarding electrons, low energy spread and short length of the bunches. The scheme of the injector is shown. The electromagnetic field simulation and longitudinal beam dynamics are presented. The possible using of the injector is discussed.

  13. Measures to alleviate the back bombardment effect of thermionic rf electron gun

    International Nuclear Information System (INIS)

    Huang, Y.; Xie, J.

    1991-01-01

    Thermionic rf electron gun finds application as a high brightness electron source for rf linacs. However, cathode heating from back-bombardment effect causes a ramp in the macro-pulse beam current and limit the usable pulse width. Three methods: ring cathode, magnetic deflection and laser assisted heating are studied in theory and in experiment. The results of these studies are reported

  14. An Independently Tunable Cells Thermionic RF Gun (ITC-RF GUN) for Sub-Picosecond Short Pulse

    CERN Document Server

    Hama, H; Kawai, M; Tanaka, T

    2005-01-01

    As a result of simulation study so far, a specific feature has been found in the longitudinal dynamics in thermionic RF guns. At the beginning of beam extraction, the head of the electrons from a cathode is followed immediately by the electrons just behind, which is extracted by the higher electric field than that at the head of the beam train. Thus later electrons would get velocity faster than the head of the electrons, so that the electrons are expected to concentrates onto the head of the beam under certain conditions such as the gun geometry and the strength of the RF field. In order to investigate this velocity-bunching like effect, a prototype thermionic RF gun was designed and its characteristics have been studied by a 3-D simulation code based on a FDTD (finite difference time demain) method. The gun is consists of two independentlly power feeding S-band RF cavities, and can be operated at modes with different power ratio and phase between two RFs. This paper report the thermionic RF gun is expected ...

  15. Development of plasma cathode electron guns

    Science.gov (United States)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  16. rf traveling-wave electron gun for photoinjectors

    Directory of Open Access Journals (Sweden)

    Mattia Schaer

    2016-07-01

    Full Text Available The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.

  17. rf traveling-wave electron gun for photoinjectors

    Science.gov (United States)

    Schaer, Mattia; Citterio, Alessandro; Craievich, Paolo; Reiche, Sven; Stingelin, Lukas; Zennaro, Riccardo

    2016-07-01

    The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL) machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least) double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.

  18. Single-side electron multipacting at the photocathode in rf guns

    Directory of Open Access Journals (Sweden)

    Jang-Hui Han

    2008-01-01

    Full Text Available Multiple electron impacting (multipacting can take place in rf fields when the rf components are composed of materials with a secondary electron yield greater than one. In rf gun cavities, multipacting may change the properties of the vacuum components or even damage them. First systematic measurements of the multipacting occurring in a photocathode rf gun were made at the Fermilab/NICADD Photoinjector Laboratory in 2000. The multipacting properties were found to depend on the cathode material and the solenoid field configuration. In this study, we measure the multipacting properties in more detail and model the secondary electron generation for numerical simulation. Measurements and simulations for the photoinjectors at Fermilab and DESY are compared. The multipacting takes place at the photocathode in rf guns and is categorized as single-side multipacting. In a low rf field, the electrons emitted from the cathode area do not leave the gun cavity within one rf cycle and have an opportunity to travel back and hit the cathode. The solenoid field distribution in the vicinity of the cathode changes the probability of electron bombardment of the cathode and makes a major contribution to the multipacting behavior.

  19. Quantum efficiency temporal response and lifetime of a GaAs cathode in SRF electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Wang, E.; Ben-Zvi, I.; Kewisch, J.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

    2010-05-23

    RF electron guns with a strained super lattice GaAs cathode can generate polarized electron beam of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface. In a normal conducting RF gun, the extremely high vaccum required by these cathodes can not be met. We report on an experiment with a superconducting SRF gun, which can maintain a vacuum of nearly 10-12 torr because of cryo-pumping at the temperature of 4.2K. With conventional activation, we obtained a QE of 3% at 532 nm, with lifetime of nearly 3 days in the preparation chamber. We plan to use this cathode in a 1.3 GHz 1/2 cell SRF gun to study its performance. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper. Future particle accelerators such as eRHIC and ILC require high brightness, high current polarized electrons Recently, using a superlattice crystal, the maximum polarization of 95% was reached. Activation with Cs,O lowers the electron affinity and makes it energetically possible for all the electrons excited in to the conduction band and reach the surface to escape into the vacuum. Presently the polarized electron sources are based on DC gun, such as that at the CEBAF at Jlab. In these devices, the life time of the cathode is extended due to the reduced back bombardment in their UHV conditions. However, the low accelerating gradient of the DC guns lead to poor longitudinal emittance. The higher accelerating gradient of the RF gun generates low emittance beams. Superconducting RF guns combine the excellent vacuum conditions of the DC guns with the higher accelerating gradients of the RF guns and provide potentially a long lived cathode with very low transverse and longitudinal emittance. In our work at BNL, we successfully activated the GaAs. The quantum efficient is 3% at 532 nm and is

  20. Quantum efficiency temporal response and lifetime of a GaAs cathode in SRF electron gun

    International Nuclear Information System (INIS)

    Wang, E.; Ben-Zvi, I.; Kewisch, J.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

    2010-01-01

    RF electron guns with a strained super lattice GaAs cathode can generate polarized electron beam of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface. In a normal conducting RF gun, the extremely high vaccum required by these cathodes can not be met. We report on an experiment with a superconducting SRF gun, which can maintain a vacuum of nearly 10-12 torr because of cryo-pumping at the temperature of 4.2K. With conventional activation, we obtained a QE of 3% at 532 nm, with lifetime of nearly 3 days in the preparation chamber. We plan to use this cathode in a 1.3 GHz 1/2 cell SRF gun to study its performance. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper. Future particle accelerators such as eRHIC and ILC require high brightness, high current polarized electrons Recently, using a superlattice crystal, the maximum polarization of 95% was reached. Activation with Cs,O lowers the electron affinity and makes it energetically possible for all the electrons excited in to the conduction band and reach the surface to escape into the vacuum. Presently the polarized electron sources are based on DC gun, such as that at the CEBAF at Jlab. In these devices, the life time of the cathode is extended due to the reduced back bombardment in their UHV conditions. However, the low accelerating gradient of the DC guns lead to poor longitudinal emittance. The higher accelerating gradient of the RF gun generates low emittance beams. Superconducting RF guns combine the excellent vacuum conditions of the DC guns with the higher accelerating gradients of the RF guns and provide potentially a long lived cathode with very low transverse and longitudinal emittance. In our work at BNL, we successfully activated the GaAs. The quantum efficient is 3% at 532 nm and is expected

  1. The on axis coupled structure type RF gun

    CERN Document Server

    Oda, F; Nakayama, A; Tanabe, E

    1999-01-01

    The fundamental design of this newly developed RF gun with a thermionic cathode is the pi/2 mode standing wave structure. It has two accelerating cells and a coupling cell located on the beam axis, a so-called on axis coupled structure (OCS). This structure offers a stable operation for high beam current, owing to high group velocity and wide bandwidth. It is important to reduce damage onto the cathode caused by back bombardment, especially for long macropulse operation, such as in an FEL injector. Back bombardment, as well as output beam profile was simulated by using the electromagnetic field analytical codes 'EMSYS'(2D) and 'MAFIA'(3D). The cavity shape was optimized to reduce back bombardment power without sacrificing beam emittance.

  2. Design study on an independently-tunable-cells thermionic RF gun

    International Nuclear Information System (INIS)

    Hama, H.; Tanaka, T.; Hinode, F.; Kawai, M.

    2006-01-01

    Characteristics of a thermionic RF gun have been studied by a 3-D simulation code developed using an FDTD (Finite Difference Time Domain) method as a Maxwell's equations solver. The gun is consists of two independent power feeding cavities, so that we call it independently-tunable-cells (ITC)'-RF gun. The first cell is the cathode cell and the second one is an accelerating cell. The ITC gun can be operated at various modes of different RF-power ratio and phase between two cavities. Simulation study shows a velocity-bunching like effect may be occurred in the gun, so that the short pulse beam from the thermionic RF gun is a better candidate to produce the coherent THz synchrotron radiation. Expected bunch length with a total charge of ∼20 pC (1% energy width from the top energy) is around 200 fs (fwhm). Even the beam energy extracted from the gun is varied by which the input powers are changed, almost same shape of the longitudinal phase space can be produced by tuning the phase. (author)

  3. Cathode follower RF system with frequency modulation

    International Nuclear Information System (INIS)

    Irie, Y.; Yano, Y.; Kaneko, N.; Kobayashi, Y.

    1994-01-01

    A model RF system with a cathode follower was tested under frequency modulation in the 1-3.5 MHz range. The repetition rate was 40 Hz. The oscillation was stable, and the output impedance was measured to be around 20 ohm. (author)

  4. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    International Nuclear Information System (INIS)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-01-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012 © . RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance

  5. Design study of a low-emittance high-repetition rate thermionic rf gun

    Science.gov (United States)

    Opanasenko, A.; Mytrochenko, V.; Zhaunerchyk, V.; Goryashko, V. A.

    2017-05-01

    We propose a novel gridless continuous-wave radiofrequency (rf) thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

  6. Function of bunching segment in multi-cell RF gun

    International Nuclear Information System (INIS)

    Yang Xingfan; Xu Zhou Liu Xisan

    2001-01-01

    With a bunching segment and a shortened first cell, the 4 + 1/2 cell RF gun produced in CAEP has been proved experimentally to be effective in reducing electron back bombardment. The analysis of the electric field distribution and electron motion in bunching segment of multi-cell RF gun is presented. The electron capture efficiency and electron trajectory with different initial phase are calculated using Runge-Kutta method. The function of the bunching segment is discussed. The calculated parameters of the 4 + 1/2 cell RF gun agree well with the experimental results

  7. The Development of the Linac Coherent Light Source RF Gun

    International Nuclear Information System (INIS)

    Dowell, D

    2008-01-01

    The Linac Coherent Light Source (LCLS) is the first x-ray laser user facility based upon a free electron laser (FEL) requiring extraordinary beam quality to saturate at 1.5 angstroms within a 100 meter undulator.[1] This new type of light source is using the last kilometer of the three kilometer linac at SLAC to accelerate the beam to an energy as high as 13.6 GeV and required a new electron gun and injector to produce a very bright beam for acceleration. At the outset of the project it was recognized that existing RF guns had the potential to produce the desired beam but none had demonstrated it. Therefore a new RF gun or at least the modification of an existing gun was necessary. The parameters listed in Table 1 illustrate the unique characteristics of LCLS which drive the requirements for the electron gun as given in Table 2. The gun beam quality needs to accommodate emittance growth as the beam is travels through approximately one kilometer of linac and two bunch compressors before reaching the undulator. These beam requirements were demonstrated during the recent commissioning runs of the LCLS injector and linac [2] due to the successful design, fabrication, testing and operation of the LCLS gun. The goal of this paper is to relate the technical background of how the gun was able to achieve and in some cases exceed these requirements by understanding and correcting the deficiencies of the prototype s-band RF photocathode gun, the BNL/SLAC/UCLA Gun III. This paper begins with a brief history and technical description of Gun III and the Gun Test Facility (GTF) at SLAC, and studies of the gun's RF and emittance compensation solenoid. The work at the GTF identified the gun and solenoid deficiencies, and helped to define the specifications for the LCLS gun. Section 1.1.5 describes the modeling used to compute and correct the gun RF fields and Section 1.1.6 describes the use of these fields in the electron beam simulations. The magnetic design and measurements of

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

    Directory of Open Access Journals (Sweden)

    R. Ganter

    2010-09-01

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

  9. Finite element analyses for RF photoinjector gun cavities

    International Nuclear Information System (INIS)

    Marhauser, F.

    2006-01-01

    This paper details electromagnetical, thermal and structural 3D Finite Element Analyses (FEA) for normal conducting RF photoinjector gun cavities. The simulation methods are described extensively. Achieved results are presented. (orig.)

  10. A numerical study of emittance growths in RF guns

    CERN Document Server

    Masuda, K; Sobajima, M; Kitagaki, J; Ohnishi, M; Toku, H; Yoshikawa, K

    1999-01-01

    A beam with greatly reduced emittance is required for further improvements of FELs, in particular, for FELs of shorter wavelengths, and of narrower bandwidths. From this viewpoint, the BNL/SLAC/UCLA 1.6-cell S-band photocathode RF gun performance characteristics were calculated, first in order to evaluate what may contribute to the emittance growths in photocathode RF guns. We developed an RF gun to produce an electron beam with an extremely low emittance, by using a 2-D simulation code. It is found that, by optimizing the laser injection phase, the drive laser spot radius and the cavity shape around the laser spot, the beam emittance by the 1.6-cell RF gun can be greatly reduced to 2.1 pi mm mrad, from the previous 4.4 pi mm mrad of the original shape.

  11. Electron beam gun with kinematic coupling for high power RF vacuum devices

    Science.gov (United States)

    Borchard, Philipp

    2016-11-22

    An electron beam gun for a high power RF vacuum device has components joined by a fixed kinematic coupling to provide both precise alignment and high voltage electrical insulation of the components. The kinematic coupling has high strength ceramic elements directly bonded to one or more non-ductile rigid metal components using a high temperature active metal brazing alloy. The ceramic elements have a convex surface that mates with concave grooves in another one of the components. The kinematic coupling, for example, may join a cathode assembly and/or a beam shaping focus electrode to a gun stem, which is preferably composed of ceramic. The electron beam gun may be part of a high power RF vacuum device such as, for example, a gyrotron, klystron, or magnetron.

  12. Femtosecond precision measurement of laser–rf phase jitter in a photocathode rf gun

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Libing; Zhao, Lingrong; Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhu, Pengfei; Xiang, Dao, E-mail: dxiang@sjtu.edu.cn

    2017-03-21

    We report on the measurement of the laser–rf phase jitter in a photocathode rf gun with femtosecond precision. In this experiment four laser pulses with equal separation are used to produce electron bunch trains; then the laser–rf phase jitter is obtained by measuring the variations of the electron bunch spacing with an rf deflector. Furthermore, we show that when the gun and the deflector are powered by the same rf source, it is possible to obtain the laser–rf phase jitter in the gun through measurement of the beam–rf phase jitter in the deflector. Based on these measurements, we propose an effective time-stamping method that may be applied in MeV ultrafast electron diffraction facilities to enhance the temporal resolution.

  13. Development of a novel thermionic RF electron gun applied on a compact THz-FEL facility

    Science.gov (United States)

    Hu, T. N.; Pei, Y. J.; Qin, B.; Liu, K. F.; Feng, G. Y.

    2018-04-01

    The current requirements from civil and commercial applications lead to the development of compact free-electron laser (FEL)-based terahertz (THz) radiation sources. A picosecond electron gun plays an important role in an FEL-THz facility and attracts significant attention, as machine performance is very sensitive to initial conditions. A novel thermionic gun with an external cathode (EC) and two independently tunable cavities (ITCs) has been found to be a promising alternative to conventional electron sources due to its remarkable characteristics, and correspondingly an FEL injector can achieve a balance between a compact layout and high brightness benefitting from the velocity bunching properties and RF focusing effects in the EC-ITC gun. Nevertheless, the EC-ITC gun has not been extensively examined as part of the FEL injector in the past years. In this regard, to fill this gap, a development focusing on the experimental setup of an FEL injector based on an EC-ITC gun is described in detail. Before assembly, dynamic beam simulations were performed to investigate the optimal mounting position for the Linac associated with the focusing coils, and a suitable radio-frequency (RF) system was established based on a power coupling design and allocation. The testing bench proved to be fully functional through basic experiments using typical diagnostic approaches for estimating primary parameters. Associated with dynamic beam calculations, a performance evaluation for an EC-ITC gun was established while providing indirect testing results for an FEL injector.

  14. Particle Simulations of a Thermionic RF Gun with Gridded Triode Structure for Reduction of Back-Bombardment

    CERN Document Server

    Kusukame, K; Kii, T; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    Thermionic RF guns show advantageous features compared with photocathode ones such as easy operation and much higher repetition rate of micropulses, both of which are suitable for their application to high average power FELs. They however suffer from the back-bombardment effect [1], i.e., in conventional RF guns, electrons are extracted from cathode also in the latter half of accelerating phase and tend to back-stream to hit the cathode, and as a result the macropulse duration is limited down to severalμsec Against this adverse effect in thermionic RF guns, introduction of the triode structure has been proposed [2], where the accelerating phase and amplitude nearby the cathode can be controlled regardless of the phase of the first accelerating cell in the conventional RF gun. Our one-dimensional particle simulation results predict that the back-bombardment power can be reduced by 99 % only with 30-40 kW RF power fed to the grid in the present triode structure with an optimal phase difference from th...

  15. Plasma gun with coaxial powder feed and adjustable cathode

    Science.gov (United States)

    Zaplatynsky, Isidor (Inventor)

    1991-01-01

    An improved plasma gun coaxially injects particles of ceramic materials having high melting temperatures into the central portion of a plasma jet. This results in a more uniform and higher temperature and velocity distribution of the sprayed particles. The position of the cathode is adjustable to facilitate optimization of the performance of the gun wherein grains of the ceramic material are melted at lower power input levels.

  16. Fabrication and description of a cold cathode electron gun

    International Nuclear Information System (INIS)

    Sari, A.H.; Ghorannevis, M.; Hantehzadeh, M.R.; Yousefi, M.R.

    2003-01-01

    In this study the structure and schematic configuration of a cold cathode electron gun has been shown, which use obstructed discharge for electron producing. This type of discharge and mechanism of secondary electron emission by ions and fast neutral interaction have been described. The experiment starts in pressure of 1*10 -3 torr, in existence of helium gas. A negative DC voltage apply to a concave cathode up to -20 k V which determine electron energy

  17. First operation of cesium telluride photocathodes in the TTF injector RF gun

    CERN Document Server

    Sertore, D; Flöttmann, K; Stephan, F; Zapfe, K; Michelato, P

    2000-01-01

    During the run 1998/1999 a new injector based on a laser-driven RF gun was brought in operation at the TESLA Test Facility (TTF) linac at DESY, in order to produce the beam structure and quality required either by TeV collider and SASE FEL experiments. High quantum efficiency cesium telluride photocathodes, prepared at Milano and transferred to DESY, have been successfully operated in the RF gun. A bunch charge of 50 nC, only limited by space charge effects, was achieved. The photocathodes have shown an operative lifetime of several months. A new cathode surface finishing has showed a promising decrease of the photocathode dark current. Measurements of dark current, quantum efficiency and lifetime are reported.

  18. Measurements of Transverse Emittance for RF Photocathode Gun at the PAL

    CERN Document Server

    Park Jang Ho; Park, Sung-Ju; Soo Ko In; Wang, Xijie; Woon Parc, Yong; Xiang, Dao

    2005-01-01

    A BNL GUN-IV type RF photo-cathode gun is under fabrication for use in the FIR (Far Infra-Red) facility being built at the Pohang Accelerator Laboratory (PAL). Performance test of the gun will include the measurement of transverse emittance profile along the longitudinal direction. Successful measurement of the emittance profile will provide powerful tool for the commissioning of the 4GLS (4th generation light source) injectors based on the emittance compensation principle. We are going to achieve this withthe use of pepper-pot based emittance meters that can be moved along the longitudinal direction. In this article, we present design considerations on the emittance meter with the resolution of 1 mm mrad.

  19. Demonstration of cathode emittance dominated high bunch charge beams in a DC gun-based photoinjector

    Science.gov (United States)

    Gulliford, Colwyn; Bartnik, Adam; Bazarov, Ivan; Dunham, Bruce; Cultrera, Luca

    2015-03-01

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (≥100 pC) beams produced in the DC gun-based Cornell energy recovery linac photoinjector. In particular, we show that the cathode thermal and core beam emittances dominate the final 95% and core emittances measured at 9-9.5 MeV. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances. These results, previously thought achievable only with RF guns, demonstrate that DC gun based photoinjectors are capable of delivering beams with sufficient single bunch charge and beam quality suitable for many current and next generation accelerator projects such as Energy Recovery Linacs and Free Electron Lasers.

  20. Demonstration of cathode emittance dominated high bunch charge beams in a DC gun-based photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Gulliford, Colwyn, E-mail: cg248@cornell.edu; Bartnik, Adam, E-mail: acb20@cornell.edu; Bazarov, Ivan; Dunham, Bruce; Cultrera, Luca [CLASSE, Cornell University, 161 Synchrotron Drive Ithaca, New York 14853-8001 (United States)

    2015-03-02

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (≥100 pC) beams produced in the DC gun-based Cornell energy recovery linac photoinjector. In particular, we show that the cathode thermal and core beam emittances dominate the final 95% and core emittances measured at 9–9.5 MeV. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances. These results, previously thought achievable only with RF guns, demonstrate that DC gun based photoinjectors are capable of delivering beams with sufficient single bunch charge and beam quality suitable for many current and next generation accelerator projects such as Energy Recovery Linacs and Free Electron Lasers.

  1. Low power microwave tests on RF gun prototype of the Iranian Light Source Facility

    Directory of Open Access Journals (Sweden)

    A Sadeghipanah

    2017-08-01

    Full Text Available In this paper, we introduce RF electron gun of Iranian Light Source Facility (ILSF pre-injection system. Design, fabrication and low-power microwave tests results of the prototype RF electron gun have been described in detail. This paper also explains the tuning procedure of the prototype RF electron gun to the desired resonant frequency. The outcomes of this project brighten the path to the fabrication of the RF electron gun by the local industries  

  2. A Two-Frequency RF Cavity for the PSI Low Emittance Gun

    CERN Document Server

    Raguin, J Y; Li, K S B; Pedrozzi, M

    2005-01-01

    In the Low Emittance Gun (LEG) under development at PSI an extremely bright electron beam is produced from a field emission array and then rapidly accelerated in a diode configuration up to 1 MeV with gradients of the order of 250 to 500 MV/m. The electronic emission from such a cold cathode allows normalized intrinsic emittance below 0.1 mm.mrad well suited for X-ray FELs or linear collider applications. The diode is followed by an L-band RF-gun like cavity to further accelerate the beam. A third harmonic field is superposed to the fundamental [1] 1.5 GHz pi-mode field to minimize the RF emittance. We report here on the design of such a two-frequency RF cavity with some details on the RF coupling and possible tuning mechanisms. Beam dynamics studies, performed with PARMELA and the fully self-consistent code MAFIA, are presented and compared with the results obtained for an RF cavity excited with the fundamental frequency only.

  3. Extreme regimes of femtosecond photoemission from a copper cathode in a dc electron gun

    Directory of Open Access Journals (Sweden)

    P. L. E. M. Pasmans

    2016-10-01

    Full Text Available The femtosecond photoemission yield from a copper cathode and the emittance of the created electron beams has been studied in a 12  MeV/m, 100 keV dc electron gun over a wide range of laser fluence, from the linear photoemission regime until the onset of image charge limitations and cathode damaging. The measured photoemission curves can be described well with available theory which includes the Schottky effect, second-order photoemission, and image charge limitation. The second-order photoemission can be explained by thermally assisted one-photon photoemission (1PPE and by above-threshold two-photon photoemission (2PPE. Measurements with a fresh cathode suggest that the 2PPE process is dominant. The beam emittance has been measured for the entire range of initial surface charge densities as well. The emittance measurements of space-charge dominated beams can be described well by an envelope equation with generalized perveance. The dc gun produces 0.1 pC bunches with 25 nm rms normalized emittance, corresponding to a normalized brightness usually associated with rf photoguns. In this experimental study the limits of femtosecond photoemission from a copper cathode have been explored and analyzed in great detail, resulting in improved understanding of the underlying mechanisms.

  4. Detailed numerical studies of space charge effects in an FEL RF gun

    CERN Document Server

    Cee, R R; Setzer, S; Weiland, T; Novokhatski, A

    2002-01-01

    The production of short bunches with low emittance is a key issue for the successful operation of an SASE-FEL as proposed by the TESLA collaboration (TESLA Technical design report, DESY 2001-011, Hamburg, 2001). In this paper we present the results of detailed MAFIA TS-2 (CST GmbH, Buedinger Strasse 2a, D-64289 Darmstadt) simulations for the FEL RF-gun revealing the main physical effects leading to emittance growth. The simulations prove that the transverse emittance growth can mainly be observed close to the cathode area. This is caused by the non-linear space charge forces acting inside the bunch during the injection process. For the application of an emittance compensation scheme (Nucl. Instr. and Meth. 285 (1989) 313) the slice emittance is of significant importance. Therefore, a wide range of parameters for the photo cathode laser has been investigated in order to find an appropriate operation point.

  5. Integration of the PHIN RF Gun into the CLIC Test Facility

    CERN Document Server

    Döbert, Steffen

    2006-01-01

    CERN is a collaborator within the European PHIN project, a joint research activity for Photo injectors within the CARE program. A deliverable of this project is an rf Gun equipped with high quantum efficiency Cs2Te cathodes and a laser to produce the nominal beam for the CLIC Test Facility (CTF3). The nominal beam for CTF3 has an average current of 3.5 A, 1.5 GHz bunch repetition frequency and a pulse length of 1.5 ìs (2332 bunches) with quite tight stability requirements. In addition a phase shift of 180 deg is needed after each train of 140 ns for the special CLIC combination scheme. This rf Gun will be tested at CERN in fall 2006 and shall be integrated as a new injector into the CTF3 linac, replacing the existing injector consisting of a thermionic gun and a subharmonic bunching system. The paper studies the optimal integration into the machine trying to optimize transverse and longitudinal phase space of the beam while respecting the numerous constraints of the existing accelerator. The presented scheme...

  6. Cathode Stalk Cooling System for the MK 1 Quarterwave Gun

    Science.gov (United States)

    2012-06-01

    that is a copper hollow tube (very similar to the cathode stalk), which can also be moved longitudinally to manipulate the coupling into the cavity...subtraction was used to determine these results in Photoshop by layering the two images and taking the difference. This is with a resolution of about 2.8... photo injectors,” Proceedings of the 2009 Superconducting RF Conference, Berlin, Germany, Rep. MOOBAU03, 2009. [11] S. P. Niles et al., “NPS prototype

  7. A novel electron gun with an independently addressable cathode array

    Energy Technology Data Exchange (ETDEWEB)

    Rudys, Joseph Matthew; Reed, Kim Warren; Pena, Gary Edward; Schneider, Larry X.

    2006-08-01

    The design of a novel electron gun with an array of independently addressable cathode elements is presented. Issues relating to operation in a 6.5 Tesla axial magnetic field are discussed. Simulations with the TriComp electromagnetic field code that were used to determine the space charge limited tube characteristic and to model focusing of the electron beam in the magnetic field are reviewed. Foil heating and stress calculations are discussed. The results of CYLTRAN simulations yielding the energy spectrum of the electron beam and the current transmitted through the foil window are presented.

  8. Construction and Test of a Novel Superconducting RF Electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Bisognano, Joseph J. [University of Wisconsin-Madison

    2014-04-16

    The University of Wisconsin-Madison has completed installation of a superconducting electron gun. Its concept was optimized to be the source for a CW free electron laser facility with multiple megahertz repetition rate end stations. This VHF superconducting configuration holds the promise of the highest performance for CW injectors. Initial commissioning efforts show that the cavity can achieve gradients of 35 MV/m at the cathode position. With the cathode inserted CW operation has been achieved at 20 MV/m with good control of microphonics, negligible dark current, and Q0 > 3×109 at 4 K. Bunch charges of ~100 pC have been delivered, and first simple beam measurements made. These preliminary results are very encouraging for production of 100s pC bunches with millimeter-milliradian or smaller normalized emittances. Plans are in place to carry out more definitive studies to establish the full capabilities. However, since the grant was not renewed, the electron gun is currently mothballed, and without supplemental fund the opportunity for further work will be lost.

  9. Design and experiment of high-current low-pressure plasma-cathode e-gun

    International Nuclear Information System (INIS)

    Xie Wenkai; Li Xiaoyun; Wang Bin; Meng Lin; Yan Yang; Gao Xinyan

    2006-01-01

    The preliminary design of a new high-power low pressure plasma-cathode e-gun is presented. Based on the hollow cathode effect and low-pressure glow discharge empirical formulas, the hollow cathode, the accelerating gap, and the working gas pressure region are given. The general experimental device of the low-pressure plasma cathode electron-gun generating high current density e-beam source is shown. Experiments has been done in continuous filled-in gases and gases-puff condition, and the discharging current of 150-200 A, the width of 60 μs and the collector current of 30-80 A, the width of 60 μs are obtained. The results show that the new plasma cathode e-gun can take the place of material cathode e-gun, especially in plasma filled microwave tubes. (authors)

  10. Thermal characterization of indirectly heated axi-symmetric solid cathode electron beam gun for melting application

    International Nuclear Information System (INIS)

    Prakash, B.; Gupta, S.; Malik, P.; Mishra, K.K.; Jha, M.N.; Kandaswamy, E.; Martin, M.

    2015-01-01

    Electron beam melting gun with indirectly heated axi-symmetric solid cathode was designed, fabricated and characterized experimentally. The thermal simulation and optical analysis of the electron gun was carried out to estimate the power required to achieve the emission temperature of the solid cathode, to obtain the temperature distribution in the assembly and the beam transportation. On the basis of the thermal simulation and electron optics, the electron gun design was finalised. The electron gun assembly was fabricated and installed in the vacuum chamber for carrying out the experiment to find the actual temperature distribution. Thermocouple and two colour pyrometer were used to measure the temperature at various locations in the electron gun. The attenuation effect of the viewing port glass of the vacuum chamber was compensated in the final reading of the temperature measured by the pyrometer. The temperature of solid cathode obtained by the experiment was found to be 2800K which is the emission temperature of solid cathode. (author)

  11. Development of highly qualified UV-laser light source for rf gun

    International Nuclear Information System (INIS)

    Tomizawa, H.; Dewa, H.; Taniuchi, T.

    2004-01-01

    We have been developing stable and highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. Our gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. In present status, the short pulse energy stability of laser has been improved down to 1.3∼1.5% (rms; 10pps; 10000 shots) at the third harmonic generation. The long stability depends on the stability of modelocking at oscillator. In this improvement we just passively stabilized the system. We considered environmental controls in clean room to reduce optical damage accidents and constructed a new humidity-controlled clean room in 2003. And we re-installed the total laser system in this room in 2004. The relative humidity of this new clean room at room temperature is in a region of 50∼60 % with a stability of less than 2% (p-p). On the other hand, the ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. This laser-shaping project has been started in two steps since 2002. As the first successful test run in 2002, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2π mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run in 2004, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying the both adaptive optics to automatically shape the both spatial and temporal UV-laser profiles with a feedback routine at the same time. We report herein the principle and developing process of our laser beam quality control system. (author)

  12. Design and performance of a 30 KV electron gun with ten independent cathodes & a magnetic lens.

    Energy Technology Data Exchange (ETDEWEB)

    Rudys, Joseph Matthew; Reed, Kim Warren

    2006-08-01

    Measurements on a 30 kV electron gun with ten independent cathodes, operating in a 6.5 Tesla (T) magnetic field are presented. An earlier paper covered the design of this electron gun [1]. Experimental results are compared to model predictions. Beam current is compared to theoretical space charge limited flow.

  13. Pierce-type electron gun with a large concave LaB6 cathode

    International Nuclear Information System (INIS)

    Shintake, Tumoru; Ohba, Kunio; Matoba, Masaru; Katase, Akira

    1981-01-01

    A Pierce-type electron gun with a concave cathode of lanthanum hexaboride (LaB 6 ) 30 mm in diameter is described. At an accelerating voltage of 3 kV and a cathode temperature of 1340 0 C, a focussed electron beam of DC 300 mA was obtained. (author)

  14. Synchronizaiton Between Laser and Electron Beam at Photocathode RF Gun

    CERN Document Server

    Sakumi, Akira; Fukasawa, Atsushi; Kumagai, Noritaka; Muroya, Yusa; Tomizawa, Hiromitsu; Ueda, T; Uesaka, Mitsuru; Urakawa, Junji; Yoshii, K

    2005-01-01

    The chemical reactions of hot, room temperature and critical water in a time-range of picosecond and sub-picosecond have been carried out by the 18 MeV S-band linac and a Mg photocathode RF gun with the irradiation of third harmonic Ti: Sapphire laser, at Nuclear Engineering Research Laboratory (NERL), the University of Tokyo. Although this short bunch and 100 fs laser light are enough to perform the experiment of radiation chemistry in the time-range of sub-picosecond, the total time-resolution become worse by the instability of synchronization between laser and radio frequency of linac. We found that the fluctuation of room temperature causes the instability, particularly the cycle of turning on/off of the air-conditioner. It is shown that 0.3 °C (peak-to-peak) fluctuation of the laser-room temperature have approximately corresponded to the instability of 6 ps. We are trying to decrease the fluctuation of the room temperature, together with the local temperature stability of the Ti: Sapphire crysta...

  15. A cold cathode of a gas-discharge electron-ion gun

    International Nuclear Information System (INIS)

    1974-01-01

    A cold cathode of a gas-discharge electron-ion gun is constructed in order to continuously replace the eroded material by feeding a wire or a set of coaxial cylinders in the spot where the ions hit the cathode. In this way, the form of the cathode and the electric-field configuration is preserved which guarantees the conservation of a sharp narrow electron beam profile

  16. Beam Dynamics Simulation of Photocathode RF Electron Gun at the PBP-CMU Linac Laboratory

    Science.gov (United States)

    Buakor, K.; Rimjaem, S.

    2017-09-01

    Photocathode radio-frequency (RF) electron guns are widely used at many particle accelerator laboratories due to high quality of produced electron beams. By using a short-pulse laser to induce the photoemission process, the electrons are emitted with low energy spread. Moreover, the photocathode RF guns are not suffered from the electron back bombardment effect, which can cause the limited electron current and accelerated energy. In this research, we aim to develop the photocathode RF gun for the linac-based THz radiation source. Its design is based on the existing gun at the PBP-CMU Linac Laboratory. The gun consists of a one and a half cell S-band standing-wave RF cavities with a maximum electric field of about 60 MV/m at the centre of the full cell. We study the beam dynamics of electrons traveling through the electromagnetic field inside the RF gun by using the particle tracking program ASTRA. The laser properties i.e. transverse size and injecting phase are optimized to obtain low transverse emittance. In addition, the solenoid magnet is applied for beam focusing and emittance compensation. The proper solenoid magnetic field is then investigated to find the optimum value for proper emittance conservation condition.

  17. Low emittance electron beam formation with a 17 GHz RF gun

    Directory of Open Access Journals (Sweden)

    W. J. Brown

    2001-08-01

    Full Text Available We report on electron beam quality measurement results from the Massachusetts Institute of Technology 17 GHz RF gun experiment. The 1.5 cell RF gun uses a solenoid for emittance compensation. It has produced bunch charges up to 0.1 nC with beam energies up to 1 MeV. The normalized rms emittance of the beam after 35 cm of transport from the gun has been measured by a slit technique to be 3π mm mrad for a 50 pC bunch. This agrees well with PARMELA simulations at these beam energies. At the exit of the electron gun, we estimate the emittance to be about 1π mm mrad, which corresponds to a beam brightness of about 80 A/(π mm mrad^{2}. Improved beam quality should be possible with a higher energy output electron beam from the gun.

  18. ACCELERATING STRUCTURE: Ultra-low emittance X-band photocathode RF gun

    Science.gov (United States)

    Tang, Chuan-Xiang; Liu, Xiao-Han

    2009-06-01

    In this paper, we present the simulation results of a 1.6 cell X-band photocathode RF gun for ultra-low emittance electron beams. It will work at 9.3 GHz. The emittance, bunch length, electron energy and energy spread at the gun exit are optimized at bunch charge of 1pC using PARMELA. Electron bunches with emittance about 0.1 mm · mrad and bunch length less than 100 fs can be obtained from this gun. A PITZ type coupler is adopted in this gun and an initial simulation by MAFIA is also given in this paper.

  19. Thermionic RF Gun and Linac Pre-Injector for SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.

    2003-08-11

    Preparations are underway to upgrade the Spear2 to the third generation light source. Installation of all the subsystems will start in April 2003. Although the Spear3 RF system is entirely different from the present form, the pre-injector gun/linac and booster synchrotron will remain the same even after the upgrade. The thermionic rf gun reliability and stability are to be improved to inject 500 mA of stored current in shortest possible time. When a top-up mode is enforced, where the stored beam decay is replenished to maintain the constant current and thus constant light intensity, the Spear3 will take injection every few minutes. In that case the gun, linac, and booster must stay on at all times. In this report we will describe some improvements made on the gun and linac in the recent past, as well as their present performance and future upgrade to be made.

  20. Development of Adaptive Feedback Control System of Both Spatial and Temporal Beam Shaping for UV-Laser Light Source for RF Gun

    CERN Document Server

    Tomizawa, H; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Yanagida, K

    2004-01-01

    The ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. We have been developing highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. The gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. The electron beam was accelerated up to 4.1 MeV at the maximum electric field on the cathode surface of 175 MV/m. For emittance compensation, two solenoid coils were used. As the first test run, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2 π·mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We applied the both adaptive optics to automatically shape the bot...

  1. A CW normal-conductive RF gun for free electron laser and energy recovery linac applications

    Energy Technology Data Exchange (ETDEWEB)

    Baptiste, Kenneth; Corlett, John; Kwiatkowski, Slawomir; Lidia, Steven; Qiang, Ji; Sannibale, Fernando; Sonnad, Kiran; Staples, John; Virostek, Steven; Wells, Russell

    2008-10-08

    Currently proposed energy recovery linac and high average power free electron laser projects require electron beam sources that can generate up to {approx} 1 nC bunch charges with less than 1 mmmrad normalized emittance at high repetition rates (greater than {approx} 1 MHz). Proposed sources are based around either high voltage DC or microwave RF guns, each with its particular set of technological limits and system complications. We propose an approach for a gun fully based on mature RF and mechanical technology that greatly diminishes many of such complications. The concepts for such a source as well as the present RF and mechanical design are described. Simulations that demonstrate the beam quality preservation and transport capability of an injector scheme based on such a gun are also presented.

  2. The SSRL linacs for injection to the storage ring and rf gun testing

    International Nuclear Information System (INIS)

    Park, Sanghyun; Weaver, James N.

    1996-01-01

    The Stanford Synchrotron Radiation Laboratory (SSRL) operates two linac systems. One has three SLAC type linac sections powered by two klystrons for injection of electrons at 120 MeV into the booster ring, boosting the energy to 2.3 GeV to fill the SPEAR. After the ramping, the SPEAR stores up to 100 mA of the beam at 3.0 GeV. The preinjector consists of a thermionic RF gun, an alpha magnet, and a chopper along with focusing magnets. The other has one 10 foot section powered by the injector klystron for the testing of RF gun with photocathode, which is driven by a separate klystron. This paper describes present systems with their operational parameters, followed by plans for the upgrades and RF gun development efforts at the SSRL. (author)

  3. Analysis and experiments of a waveguide post's influence on photocathode RF gun

    Energy Technology Data Exchange (ETDEWEB)

    Qian Houjun [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)], E-mail: qhj@mails.thu.edu.cn; Tang Chuanxiang; Zheng Shuxin; Tong Dechun; Chen Huaibi; Huang Wenhui; Guan Xin [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2008-12-01

    Several BNL/KEK/SHI type photocathode RF guns have been fabricated for high-quality electron beams in Accelerator Laboratory of Tsinghua University. This paper describes how the characteristics of a waveguide post can be chosen to correct for a mismatch in power coupling without affecting the pi-mode resonant frequency and the balance of fields between the two cells. Microwave circuit theories are used to analyze how to select the proper location and depth of the waveguide post. The tolerance on the post positioning is evaluated based on gun field quality requirements. MAFIA simulations and RF experiments have been done to confirm the theoretical analysis.

  4. The Grumman/Brookhaven high-brightness, high-duty factor RF gun

    International Nuclear Information System (INIS)

    Lehrman, I.S.; Birnbaum, I.A.; Cole, M.; Fixler, S.Z.; Heuer, R.L.; Siddiqi, S.; Sheedy, E.; Waren, G.D.

    1992-01-01

    Under a joint collaboration between Brookhaven National Laboratory and the Grumman Corporation, a high-duty (>1%) photocathode RF gun is under construction for use at the ATF facility at BNL. The gun will be capable of producing short ( 300 A (after compression) and a total bunch charge in excess of 3 nC. The gun consists of 3-1/2 cells constructed from GlidCop, an alumina dispersion strengthened copper alloy. Two individually phased waveguides are used to power the first two and final two cells. (Author) 10 refs., 8 figs., 2 tabs

  5. Bunch length monitor using two-frequency analysis for RF gun system

    International Nuclear Information System (INIS)

    Kuroda, Ryunosuke; Kashiwagi, Shigeru; Sakaue, Kazuyuki; Washio, Masakazu; Hayano, Hitoshi; Urakawa, Junji

    2004-01-01

    An rms (root mean square) bunch length monitor for a laser-driven photocathode rf gun system on a two-frequency analysis technique has been developed. Typically, the photoelectron beam generated from the rf gun system has an energy of 3-5 MeV and an rms bunch length smaller than 20 ps down to 3-4 ps. This monitor is suitable for such electron beam measurement. The rms bunch length as a function of rf phase was experimentally measured using both the rms bunch length monitor and streak camera technique using a 50 MeV electron beam at the KEK accelerator test facility (KEK-ATF) injector section which has an rf gun system and a 3-m-long accelerator structure. A numerical simulation study was also performed using the PARMELA code. The availability of this monitor was clearly verified by comparing the results. Consequently, this monitor was installed in the rf gun system at Waseda University and the rms bunch length measurement for a 3.5 MeV electron beam was precisely performed using the monitor. (author)

  6. Experimental studies of emittance growth and energy spread in a photocathode RF gun

    International Nuclear Information System (INIS)

    Yang, J.; Sakai, F.; Okada, Y.; Yorozu, M.; Yanagida, T.; Endo, A.

    2002-01-01

    In this paper we report on a low emittance electron source, based on a photocathode RF gun, a solenoid magnet and a subsequent linac. The dependencies of the beam transverse emittance and relative energy spread with respect to the laser injection phase of the radio-frequency (RF) gun, the RF phase of the linac and the bunch charge were investigated experimentally. It was found that a lower beam emittance is observed when the laser injection phase in the RF gun is low. The emittance increases almost linearly with the bunch charge under a constant solenoid magnetic field. The corrected relative energy spread of the beam is not strongly dependent on the bunch charge. Finally, an optimal normalized rms transverse emittance of 1.91±0.28 πmm mrad at a bunch charge of 0.6 nC was obtained when the RF gun was driven by a picosecond Nd:YAG laser. A corrected relative rms energy spread of 0.2-0.25% at a bunch charge of 0.3-2 nC was obtained after the beam was accelerated to 14 MeV by the subsequent linac

  7. Experimental studies of emittance growth and energy spread in a photocathode RF gun

    CERN Document Server

    Yang, J; Okada, Y; Yorozu, M; Yanagida, T; Endo, A

    2002-01-01

    In this paper we report on a low emittance electron source, based on a photocathode RF gun, a solenoid magnet and a subsequent linac. The dependencies of the beam transverse emittance and relative energy spread with respect to the laser injection phase of the radio-frequency (RF) gun, the RF phase of the linac and the bunch charge were investigated experimentally. It was found that a lower beam emittance is observed when the laser injection phase in the RF gun is low. The emittance increases almost linearly with the bunch charge under a constant solenoid magnetic field. The corrected relative energy spread of the beam is not strongly dependent on the bunch charge. Finally, an optimal normalized rms transverse emittance of 1.91+-0.28 pi mm mrad at a bunch charge of 0.6 nC was obtained when the RF gun was driven by a picosecond Nd:YAG laser. A corrected relative rms energy spread of 0.2-0.25% at a bunch charge of 0.3-2 nC was obtained after the beam was accelerated to 14 MeV by the subsequent linac.

  8. Performance of the thermionic RF gun injector for the linac-based IR free electron laser at the FEL-SUT

    CERN Document Server

    Oda, F; Kawai, M; Koike, H; Sobajima, M

    2001-01-01

    Kawasaki Heavy Industries, Ltd. (KHI) has developed a linac-based compact IR free electron laser device and has installed it in the FEL-SUT (IR FEL Research Center of Science University of Tokyo). The FEL device adopts a combination of a multi-cell RF gun with a thermionic cathode and an alpha-magnet as an injector. The fundamental design of this RF gun is the pi/2 mode standing wave structure. It has two accelerating cells and a coupling cell located on the beam axis, a so-called 'on axis coupled structure' (OCS). Characteristics of momentum distribution and micropulse bunch length of the electron beam are compared with beam dynamics simulation results in this paper. We succeeded in obtaining sufficient peak current for FEL lasing with this injector, and the first lasing was achieved on 6 July 2000.

  9. A photocathode rf gun design for a mm-wave linac-based FEL

    International Nuclear Information System (INIS)

    Nassiri, A.; Berenc, T.; Foster, J.; Waldschmidt, G.; Zhou, J.

    1995-01-01

    In recent years, advances in the rf gun technology have made it possible to produce small beam emittances suitable for short period microundulators which take advantage of the low emittance beam to reduce the wavelength of FELs. At the Advanced Photon Source, we are studying the design of a compact 50-MeV superconducting mm-wave linac-based FEL for the production of short wavelengths (∼300 nm) to carry out FEL demonstration experiments. The electron source considered for the linac is a 30- GHz, 3 1/2-cell π-mode photocathode rf gun. For cold model rf measurements a 15-GHz prototype structure was fabricated. Here we report on the design, numerical modelling and the initial cold-model rf measurement results on the 15-GHz prototype structure

  10. A photocathode rf gun design for a mm-wave linac-based FEL

    Energy Technology Data Exchange (ETDEWEB)

    Nassiri, A.; Berenc, T,; Foster, J.; Waldschmidt, G.; Zhou, J.

    1995-07-01

    In recent years, advances in the rf gun technology have made it possible to produce small beam emittances suitable for short period microundulators which take advantage of the low emittance beam to reduce the wavelength of FELs. At the Advanced Photon Source, we are studying the design of a compact 50-MeV superconducting mm-wave linac-based FEL for the production of short wavelengths ({approximately}300 nm) to carry out FEL demonstration experiments. The electron source considered for the linac is a 30- GHz, 3 1/2-cell {pi}-mode photocathode rf gun. For cold model rf measurements a 15-GHz prototype structure was fabricated. Here we report on the design, numerical modelling and the initial cold-model rf measurement results on the 15-GHz prototype structure.

  11. Amorphous NEA Silicon Photocathodes - A Robust RF Gun Electron Source. Final Report

    International Nuclear Information System (INIS)

    Mulhollan, Gregory A.

    2009-01-01

    Amorphous silicon (a-Si) has been shown to have great promise as a negative electron affinity visible wavelength photocathode suitable for radio frequency (RF) gun systems. The specific operating wavelength can be shifted by growing it as a germanium alloy (a-Si(1-x)Ge(x)) rather than as pure silicon. This class of photoemitters has been shown to possess a high degree of immunity to charged particle flux. Such particle flux can be a significant problem in the operation of other photocathodes in RF gun systems. Its emission characteristics in the form of current per unit area, or current density, and emission angle, or beam spread are well matched for use in RF guns. Photocathodes made of a-Si can be fabricated on a variety of substrates including those most commonly employed in RF gun systems. Such photocathodes can be made for operation in either transmission or reflection mode. By growing them utilizing radio frequency plasma enhanced chemical vapor deposition, the unit cost is quite low, the quality is high and it is straightforward to grow custom size substrates and full or limited regions to confine the electron emission to the desired area. Quality emitters have been fabricated on tantalum, molybdenum, tungsten, titanium, copper, stainless steel, float glass, borosilicate glass and gallium arsenide. In addition to performing well in dedicated test chambers, a-Si photocathodes have been shown to function well in self-contained vacuum tubes. In this employment, they are subjected to a strenuous environment. Successful operation in this configuration provides additional confidence in their application to high energy linac photoinjectors and potentially as part of reliable, low cost photocathode driven RF gun systems that could become ready replacements for the diode and triode guns used on medical accelerators. Their applications in stand-alone vacuum tubes is just beginning to be explored.

  12. X-band RF gun and linac for medical Compton scattering X-ray source

    Science.gov (United States)

    Dobashi, Katsuhito; Uesaka, Mitsuru; Fukasawa, Atsushi; Sakamoto, Fumito; Ebina, Futaro; Ogino, Haruyuki; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Hayano, Hitoshi; Nakagawa, Keiichi

    2004-12-01

    Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year.

  13. Simulation Study of a Thermionic RF Gun for High Brightness and Short Pulse Beam

    CERN Document Server

    Tanaka, Takumi; Hinode, Fujio; Kawai, Masayuki; Miyamoto, Atsushi; Shinto, Katsuhiro

    2005-01-01

    Characteristics of thermionic RF guns are not understood completely. In particular, measured intense beam emittances extracted from thermionic RF guns do not agree well with simulated values so far. Most of simulation codes solve the equation of electron motion in an intrinsic mode of the RF field calculated by a separated code. The way of such simulation codes is not self-consistent completely. That is probably a major reason for the discrepancy between the experiments and the simulations. One of the other way for a self-consistent simulation codes is to use an FDTD (Finite Difference Time Domain) method. Since the FDTD method can take into account the microwave propagation including the space charge effect and the beam loading self-consistently, we have developed an FDTD code as 3-D Maxwell's equation solver and applied for a study of beam dynamics in a thermionic RF gun. The main purpose of simulaiton study is to obtain overall properties of the beam dynamics at the time. The goal of this simulation study ...

  14. An RF-gun-driven recirculated linac as injector and FEL driver

    CERN Document Server

    Andersson, A; Werin, S; Biedron, S G; Freund, H

    2000-01-01

    A new pre-injector for the MAX-Laboratory is under design and construction. A thermionic RF gun, designed to operate at medium currents with low back bombardment power, is under construction. The gun will, via a magnetic compressor and energy filter, feed a recirculated linac consisting of two SLED-equipped structures giving 125 MeV each. The first will be delivered in 1999. The system is aimed as a pre-injector for the existing storage rings at MAX-Lab, but will also open up possibilities for a SASE FEL in the UV reaching above 100 MW below 100 nm.

  15. Large-area cold-cathode grid-controlled electron gun for Antares

    International Nuclear Information System (INIS)

    Scarlett, W.R.; Andrews, K.; Jansen, J.

    1979-01-01

    The CO 2 laser amplifiers used in the Antares inertial confinement fusion project require large-area radial beams of high-energy electrons to ionize the laser medium before the main discharge pulse is applied. We have designed a grid-controlled, cold-cathode electron gun with a cylindrical anode having a window area of 9.3 m 2 . A full diameter, 1/4 length prototype of the Antares gun has been built and tested. The design details of the Antares electron gun will be presented as well as test results from the prototype. Techniques used for the prevention and control of emission and breakdown from the grid will also be discussed

  16. Cold cathode electron guns in the LASL high power short-pulse CO2 laser program

    International Nuclear Information System (INIS)

    Singer, S.; Ladish, J.S.; Nutter, M.J.

    1975-01-01

    The Electron Beam Controlled Discharge CO 2 Laser is now firmly established as the only high power short pulse laser amplifier that has been demonstrated to have scaling capabilities to large apertures and energies much greater than 100 J. These devices require a beam of energetic electrons to control the gas discharge that produces the required population inversion. Until recently, the electron source was usually a thermionic emitter, even for rather large lasers, whose heater requirements dwarfed the pulsed energies associated with the transient operation of the laser. With the advent of reliable cold-cathode electron guns, the operation of these lasers has been greatly simplified. At LASL, there are four electron beam controlled laser systems which are in operation, under construction, or in design: the 1 kJ system, now operational; the 2.5 kJ system; the 10 kJ system; and the 100 kJ system. Only the first uses thermionic-emitter electron guns; the remainder use or will use cold cathode sources. The operation of the 200 x 35 cm 2 two sided cold cathode electron gun used in the 2.5 kJ laser system and to be used in the 10 kJ laser is described

  17. A low-power RF system with accurate synchronization for a S-band RF-gun using a laser-triggered photocathode

    International Nuclear Information System (INIS)

    Otake, Y.; Naito, T.; Shintake, T.; Takata, K.; Takeuchi, Y.; Urakawa, J.; Yoshioka, M.; Akiyama, H.

    1992-01-01

    An S-band RF-gun using a laser-triggered photocathode and its low-power RF system have been constructed. The main elements of the low-power RF system comprise a 600-W amplifier, an amplitude modulator, a phase detector, a phase shifter and a frequency-divider module. Synchronization between the RF fields for acceleration and the mode-locked laser pulses for beam triggering are among the important points concerning the RF-gun. The frequency divider module which down-converts from 2856 MHz(RF) to 89.25 MHz(laser), and the electrical phase-shifter were specially developed for stable phase control. The phase jitter of the frequency divider should be less than 10 ps to satisfy our present requirements. The first experiments to trigger and accelerate beams with the above-mentioned system were carried out in January, 1992. (Author) 6 figs., 5 refs

  18. Status of SPring-8 Photocathode Rf Gun for Future Light Sources

    CERN Document Server

    Tomizawa, H; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Yanagida, K

    2005-01-01

    We have been studying photocathode single-cell pillbox rf gun for future light sources since 1996. We achieved a rmaximum field gradient of 187 MV/m with chemical-etching processed cavity. We have been developed stable and highly qualified UV-laser source for the rf gun intensively last 3 years. The UV-laser pulse (10 Hz) energy is up to 850 uJ/pulse. The energy stability (rms) of laser has been improved down to 0.2~0.3 % at the fundamental and 0.7~1.3% at the third harmonic generation. This stability is held for two months continuously. In this improvement, we just passively stabilized the system in a humidity-controlled clean room. On the other hand, the ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from the rf gun. We prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. With a deformable mirror, we obtained an emittance of1.6

  19. The design and development of a ring cathode electron gun as an evaporation source

    International Nuclear Information System (INIS)

    Poyner, G.T.

    1976-01-01

    The RG2 ring cathode gun is a simple application of electron beam heating. The gun described was developed to provide a relatively inexpensive source for evaporating a range of metals and oxides which were otherwise difficult or impossible to evaporate by conventional resistance heating. Following several stages of improvement the gun was progressively reduced in size and the 'optics', or focusing, improved so that in its existing state an area of approximately 2mm diameter is heated. It was decided to limit the accelerating voltage as far as possible to minimize the practical problems associated with its operation and also the manufacture of the power supply. As development proceeded it became apparent that the relatively low accelerating voltage chosen improved the flexibility of the gun. Two versions are manufactured, the first, equipped with a six position rotary hearth, and the second, utilising a single hearth, is intended to be used as one of a pair. The latter design was reduced in size even further in order to minimize the distance between two adjacent guns. (author)

  20. The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

    Science.gov (United States)

    Cornish, S.; Khachan, J.

    2016-02-01

    A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required.

  1. Survey of SRF guns

    Energy Technology Data Exchange (ETDEWEB)

    Belomestnykh, S.

    2011-07-25

    Developing Superconducting RF (SRF) electron guns is an active field with several laboratories working on different gun designs. While the first guns were based on elliptic cavity geometries, Quarter Wave Resonator (QWR) option is gaining popularity. QWRs are especially well suited for producing beams with high charge per bunch. In this talk we will describe recent progress in developing both types of SRF guns. SRF guns made excellent progress in the last two years. Several guns generated beams and one, at HZDR, injected beam into an accelerator. By accomplishing this, HZDR/ELBE gun demonstrated feasibility of the SRF gun concept with a normal-conducting Cs{sub 2}Te cathode. The cathode demonstrated very good performance with the lifetime of {approx}1 year. However, for high average current/high bunch charge operation CsK{sub 2}Sb is preferred as it needs green lasers, unlike UV laser for the Cs{sub 2}Te, which makes it easier to build laser/optics systems. Other high QE photocathodes are being developed for SRF guns, most notably diamond-amplified photocathode. Several QWR guns are under development with one producing beam already. They are very promising for high bunch charge operation. The field is very active and we should expect more good results soon.

  2. Status of the 3½ Cell Superconducting RF Gun Project in Rossendorf

    CERN Document Server

    Xiang, R; Evtushenko, Pavel; Janssen, Dietmar; Lehnert, Ulf; Michel, Peter; Möller, Karsten; Schneider, Christof; Schurig, Rico; Staufenbiel, Friedrich; Teichert, Jochen; Kamps, Thorsten; Lipka, Dirk; Volkov, Vladimir; Stephan, J; Lehmann, W D; Will, Ingo

    2005-01-01

    In the paper, we report on the status and progress of the superconducting rf gun project in Rossendorf. The gun is designed for cw operation mode with 1mA current and 10 MeV electron energy. The gun will be installed at the ELBE superconducting electron linear accelerator. It will have a 3½ cell niobium cavity operating at 1.3 GHz. The cavity consists of three cells with TESLA geometry and a specially designed half-cell in which the photocathode will be placed. Two Nb cavities, with RRR 300 and 40 respectively, will be finished at the beginning of 2005. After delivery, the rf tests will be performed and the treatment of the cavities will be started. At the same time, the design of the cryostat is finished and the fabrication of its components is under way. Further activities are the design of the diagnostic beam line, the assembling of the new photocathode preparation system, and the upgrade of the 262 nm driver laser system.

  3. Study of thermionic RF-gun phase-space dynamics and slice emittance under influence of external electromagnetic fields

    International Nuclear Information System (INIS)

    Kusoljariyakul, K.; Thongbai, C.

    2011-01-01

    A high brightness electron source of ultra-small emittance and high-average current is one of the most important components for future accelerators. In a RF-electron-gun, rapid acceleration can reduce emittance growth due to space charge effects. However, twisting or rotation of the transverse phase-space distribution as a function of time is observed in thermionic RF-electron-guns and may set a lower limit to the projected beam emittance. Such rotation being caused by the variation of the RF field with time may be compensated by fields from a specific cavity. In this work, we study RF-electron-gun phase-space dynamics and emittance under the influence of external fields to evaluate the compensation schemes.

  4. Experimental results of an rf gun and the generation of a multibunch beam

    Directory of Open Access Journals (Sweden)

    Abhay Deshpande

    2011-06-01

    Full Text Available At the laser undulator compact x-ray source at KEK, our group has designed and built a new rf gun with a larger mode separation of 8.6 MHz and higher Q value than earlier guns. This paper presents details on the design and fabrication, low-power measurements, and tuning procedures followed in the fabrication of the gun cavity. We also give a detailed account of experiments performed with this gun and present measurement results. We have successfully generated 100 bunches per train with a 50 nC charge at 41 MeV and 300 bunches per train with a 160 nC charge at 5 MeV, with low peak-to-peak energy difference. In the future, we plan to go up to a 0.5 nC charge per bunch in an 8000-bunch train at low energy and a 2 nC charge per bunch in a 100-bunch train at high energy. This will make it possible to have higher charge available for laser-beam collisions, thus enabling the generation of high flux soft x rays using the low-energy electron beam and approximately 30 keV x rays using the high-energy electron beam.

  5. Performances of the Alpha-X RF gun on the PHIL accelerator at LAL

    Science.gov (United States)

    Vinatier, T.; Bruni, C.; Roux, R.; Brossard, J.; Chancé, S.; Cayla, J. N.; Chaumat, V.; Xu, G.; Monard, H.

    2015-10-01

    The Alpha-X RF-gun was designed to produce an ultra-short (laser-driven plasma accelerator with a short wavelength accelerating medium. It has been demonstrated on PHIL (Photo-Injector at LAL) that the coaxial RF coupling, chosen to preserve the gun field cylindrical symmetry, is perfectly understood and allows reaching the required peak accelerating field of 100 MV/m giving beam energy of 6.3 MeV. Moreover, a quite low beam rms relative energy spread of 0.15% at 3.8 MeV has been measured, completely agreeing with simulations. Dark current, quantum efficiencies and dephasing curves measurements have also been performed. They all show high values of the field enhancement factor β, which can be explained by the preparation of the photocathodes. Finally, measurements on the transverse phase-space have been carried out, with some limitations given by the difficult modelization of one of the PHIL solenoid magnets and by the enlargement of the beam transverse dimensions due to the use of YAG screens. These measurements give a normalized rms transverse emittance around 5π mm mrad, which does not fulfill the requirement for the Alpha-X project.

  6. Performances of the Alpha-X RF gun on the PHIL accelerator at LAL

    Energy Technology Data Exchange (ETDEWEB)

    Vinatier, T., E-mail: vinatier@lal.in2p3.fr [Laboratoire de l' Accélérateur Linéaire (LAL), Université Paris Sud, UMR 8607, bâtiment 200, 91898 Orsay Cedex (France); Bruni, C. [Laboratoire de l' Accélérateur Linéaire (LAL), Université Paris Sud, UMR 8607, bâtiment 200, 91898 Orsay Cedex (France); Roux, R. [Laboratoire de l' Accélérateur Linéaire (LAL), Université Paris Sud, UMR 8607, bâtiment 200, 91898 Orsay Cedex (France); Laboratoire d' Etude des Eléments Légers, CEA IRAMIS, bâtiment 524, 91191 Gif sur Yvette Cedex (France); Brossard, J. [Laboratoire de l' Accélérateur Linéaire (LAL), Université Paris Sud, UMR 8607, bâtiment 200, 91898 Orsay Cedex (France); Laboratoire Astroparticule et Cosmologie, Université Paris 7, UMR 7164, bâtiment Condorcet, 75205 Paris Cedex (France); Chancé, S.; Cayla, J.N.; Chaumat, V. [Laboratoire de l' Accélérateur Linéaire (LAL), Université Paris Sud, UMR 8607, bâtiment 200, 91898 Orsay Cedex (France); and others

    2015-10-11

    The Alpha-X RF-gun was designed to produce an ultra-short (<100 fs rms), 100 pC and 6.3 MeV electron beam with a normalized rms transverse emittance of 1π mm mrad for a gun peak accelerating field of 100 MV/m. Such beams will be required by the Alpha-X project, which aims to study a laser-driven plasma accelerator with a short wavelength accelerating medium. It has been demonstrated on PHIL (Photo-Injector at LAL) that the coaxial RF coupling, chosen to preserve the gun field cylindrical symmetry, is perfectly understood and allows reaching the required peak accelerating field of 100 MV/m giving beam energy of 6.3 MeV. Moreover, a quite low beam rms relative energy spread of 0.15% at 3.8 MeV has been measured, completely agreeing with simulations. Dark current, quantum efficiencies and dephasing curves measurements have also been performed. They all show high values of the field enhancement factor β, which can be explained by the preparation of the photocathodes. Finally, measurements on the transverse phase-space have been carried out, with some limitations given by the difficult modelization of one of the PHIL solenoid magnets and by the enlargement of the beam transverse dimensions due to the use of YAG screens. These measurements give a normalized rms transverse emittance around 5π mm mrad, which does not fulfill the requirement for the Alpha-X project.

  7. Ion bombardment in RF photoguns

    Energy Technology Data Exchange (ETDEWEB)

    Pozdeyev,E.; Kayran, D.; Litvinenko, V. N.

    2009-05-04

    A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.

  8. LCLS Gun Solenoid Design Considerations

    International Nuclear Information System (INIS)

    Schmerge, John

    2010-01-01

    The LCLS photocathode rf gun requires a solenoid immediately downstream for proper emittance compensation. Such a gun and solenoid have been operational at the SSRL Gun Test Facility (GTF) for over eight years. Based on magnetic measurements and operational experience with the GTF gun solenoid multiple modifications are suggested for the LCLS gun solenoid. The modifications include adding dipole and quadrupole correctors inside the solenoid, increasing the bore to accommodate the correctors, decreasing the mirror plate thickness to allow the solenoid to move closer to the cathode, cutouts in the mirror plate to allow greater optical clearance with grazing incidence cathode illumination, utilizing pancake coil mirror images to compensate the first and second integrals of the transverse fields and incorporating a bipolar power supply to allow for proper magnet standardization and quick polarity changes. This paper describes all these modifications plus the magnetic measurements and operational experience leading to the suggested modifications.

  9. R and D of control system of compact self-bunching RF gun test facility

    International Nuclear Information System (INIS)

    Pang Jian; Pei Yuanji; Huang Guirong; Wang Jinxiang

    2010-01-01

    An experimental device was recently constructed for testing the beam characteristics of a compact self-bunching RF gun at the National Synchrotron Radiation Laboratory. It designs an independent monitor and control system for the experimental device so as not to disturb the operation of 200MeV LINAC. According to the three-level architecture of a general control scheme, the proposed system consists of circuits that execute kernel control, photosignal emission/reception, and switch values input/output, respectively. It performs timing control, device status monitoring as well as interlock protection, and it can be remotely operated with the assistance of PC software. Testing results show that our system achieves the specified performance and meets the requirement of experimental device stably and reliably. Our proposed system can also be applied to control other small-scale accelerators. (authors)

  10. Lifetime Studies of Cs2Te Cathodes at the Phin RF Photoinjector at CERN

    CERN Document Server

    Hessler, C; Divall Csatari, M; Doebert, S; Fedosseev, V

    2012-01-01

    The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 2 ns bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging concerning the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, are presented with respect to bunch charge, train length and vacuum level. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

  11. Current control of the electron beam formed in the magnetron gun with a secondary-emission cathode

    International Nuclear Information System (INIS)

    Dovbnya, A.N.; Reshetnyak, N.G.; Zakutin, V.V.; Chertishchev, I.A.; Romas'ko, V.P.; Dovbnyan, N.A.

    2013-01-01

    Data are reported on electron beam generation and beam current control in two types of secondary-emission cathode magnetron guns. The influence of the magnetic field value and field distribution on the formation of the beam and its parameters has been investigated in the electron energy range between 20 and 150 keV. The influence of local magnetic field variations on the cathode and the electron beam characteristics has been studied. The possibility to control the electron beam current in various ways has been demonstrated

  12. Adaptive shaping system for both spatial and temporal profiles of a highly stabilized UV laser light source for a photocathode RF gun

    Science.gov (United States)

    Tomizawa, H.; Dewa, H.; Taniuchi, T.; Mizuno, A.; Asaka, T.; Yanagida, K.; Suzuki, S.; Kobayashi, T.; Hanaki, H.; Matsui, F.

    2006-02-01

    We have been developing a stable and highly qualified ultraviolet (UV) laser pulse as a light source of an RF gun for an injector candidate of future light sources. Our gun cavity is a single-cell pillbox, and the copper inner wall is used as a photocathode. The chirped pulse amplification (CPA) Ti:sapphire laser system is operated at a repetition rate of 10 Hz. At the third harmonic generation (central wavelength—263 nm), the laser pulse energy after a 45 cm silica rod is up to 850 μJ/pulse. In its present status, the laser's pulse energy stability has been improved down to 0.2˜0.3% at the fundamental, and 0.7-1.4% (rms; 10 pps; 33,818 shots) at the third harmonic generation, respectively. This stability has been held for 1 month continuously, 24 h a day. The improvements we had passively implemented were to stabilize the laser system as well as the environmental conditions. We introduced a humidity-control system kept at 50-60% in a clean room to reduce damage to the optics. In addition, we prepared a deformable mirror for spatial shaping and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying both the adaptive optics to automatic optimization of the electron beam bunch to produce lower emittance with the feedback routine. Before the improvements, the electron beam produced from a cathode suffered inhomogeneous distribution caused by the quantum efficiency effect, and some pulse distortions caused by its response time. However, we can now freely form any arbitrary electron beam distribution on the surface of the cathode.

  13. A comparison of L-band and C-band rf guns as sources for inline-injection systems

    International Nuclear Information System (INIS)

    Gallardo, J.C.; Kirk, H.G.; Meyerer, T.

    1994-12-01

    We consider the beam dynamics associated with installing a BNL type 1 1/2 cell L-band or C-band rf gun before two TESLA L-band cryomodules. This system will deliver a 25 MeV electron beam with peak currents on the order of 100 A suitable for further magnetic compression. evaluate the injection systems utilizing the electron beam dynamic code PARMELA from the point of view of minimizing the transverse invariant emittance

  14. Multiobjective optimization design of an rf gun based electron diffraction beam line

    Science.gov (United States)

    Gulliford, Colwyn; Bartnik, Adam; Bazarov, Ivan; Maxson, Jared

    2017-03-01

    Multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line comprised of a 100 MV /m 1.6-cell normal conducting rf (NCRF) gun, as well as a nine-cell 2 π /3 bunching cavity placed between two solenoids, have been performed. These include optimization of the normalized transverse emittance as a function of bunch charge, as well as optimization of the transverse coherence length as a function of the rms bunch length of the beam at the sample location for a fixed charge of 1 06 electrons. Analysis of the resulting solutions is discussed in terms of the relevant scaling laws, and a detailed description of one of the resulting solutions from the coherence length optimizations is given. For a charge of 1 06 electrons and final beam sizes of σx≥25 μ m and σt≈5 fs , we found a relative coherence length of Lc ,x/σx≈0.07 using direct optimization of the coherence length. Additionally, based on optimizations of the emittance as a function of final bunch length, we estimate the relative coherence length for bunch lengths of 30 and 100 fs to be roughly 0.1 and 0.2 nm /μ m , respectively. Finally, using the scaling of the optimal emittance with bunch charge, for a charge of 1 05 electrons, we estimate relative coherence lengths of 0.3, 0.5, and 0.92 nm /μ m for final bunch lengths of 5, 30 and 100 fs, respectively.

  15. Multiobjective optimization design of an rf gun based electron diffraction beam line

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2017-03-01

    Full Text Available Multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line comprised of a 100  MV/m 1.6-cell normal conducting rf (NCRF gun, as well as a nine-cell 2π/3 bunching cavity placed between two solenoids, have been performed. These include optimization of the normalized transverse emittance as a function of bunch charge, as well as optimization of the transverse coherence length as a function of the rms bunch length of the beam at the sample location for a fixed charge of 10^{6} electrons. Analysis of the resulting solutions is discussed in terms of the relevant scaling laws, and a detailed description of one of the resulting solutions from the coherence length optimizations is given. For a charge of 10^{6} electrons and final beam sizes of σ_{x}≥25  μm and σ_{t}≈5  fs, we found a relative coherence length of L_{c,x}/σ_{x}≈0.07 using direct optimization of the coherence length. Additionally, based on optimizations of the emittance as a function of final bunch length, we estimate the relative coherence length for bunch lengths of 30 and 100 fs to be roughly 0.1 and 0.2  nm/μm, respectively. Finally, using the scaling of the optimal emittance with bunch charge, for a charge of 10^{5} electrons, we estimate relative coherence lengths of 0.3, 0.5, and 0.92  nm/μm for final bunch lengths of 5, 30 and 100 fs, respectively.

  16. DC photoemission electron guns as ERL sources

    International Nuclear Information System (INIS)

    Sinclair, Charles K.

    2006-01-01

    Very-high-voltage DC electron guns, delivering moderate duration bunches from photoemission cathodes, and followed by conventional drift bunching and acceleration, offer a practical solution for an ERL injector. In a variant of this scheme, a DC gun is placed in close proximity to a superconducting RF accelerator cavity, with few or no active elements between the gun and cavity. The principal technical challenge with such electron guns arises from field emission from the cathode electrode and its support structure. Field emission may result in voltage breakdown across the cathode-anode gap, or a punch-through failure of the insulator holding off the cathode potential, as well as lesser though still serious problems. Various means to mitigate these problems are described. The operational lifetime of high quantum efficiency photocathodes in these guns is determined by the vacuum conditions, through phenomena such as chemical poisoning and ion back-bombardment. Minimization of the field strength on electrode structures pushes high-voltage DC guns toward large dimensions and, correspondingly, large outgassing loads, but it is also true that these guns offer many opportunities for achieving excellent vacuum conditions. Good solutions to vacuum problems that had previously limited cathode lifetime have been demonstrated in recent years. Designs for DC guns presently in use and planned for the near future will be described. The parameters necessary for a 100 mA average current, very-high-voltage DC gun with a photocathode operational lifetime greater than 100 h appear to be within reach, but have yet to be demonstrated. A 1 A average current source with good cathode operational lifetime will require developments beyond the present state-of-the-art

  17. Electron dynamics in RF sources with a laser controlled emission

    CERN Document Server

    Khodak, I V; Metrochenko, V V

    2001-01-01

    Photoemission radiofrequency (RF) electron sources are sources of electron beams with extremely high brightness. Beam bunching processes in such devices are well studied in case when laser pulse duration is much lower of rf oscillation period.At the same time photoemission RF guns have some merits when operating in 'long-pulse' mode. In this case the laser pulse duration is much higher of rf oscillation period but much lower of rise time of oscillations in a gun cavity. Beam parameters at the gun output are compared for photoemission and thermoemission cathode applications. The paper presents results of a beam dynamics simulation in such guns with different resonance structures. Questions connected with defining of the current pulse peak value that can be obtained in such guns are discussed.

  18. Summary, Working Group 1: Electron guns and injector designs

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Bazarov, I.V.

    2006-01-01

    We summarize the proceedings of Working Group 1 of the 2005 Energy Recovery Linac (ERL) Workshop. The subject of this working group, the electron gun and injector design, is arguably the most critical part of the ERL as it determines the ultimate performance of this type of accelerators. Working Group 1 dealt with a variety of subjects: The technology of DC, normal-conducting RF and superconducting RF guns; beam dynamics in the gun and injector; the cathode and laser package; modeling and computational issues; magnetized beams and polarization. A short overview of these issues covered in the Working Group is presented in this paper

  19. Secondary emission electron gun using external primaries

    Science.gov (United States)

    Srinivasan-Rao, Triveni [Shoreham, NY; Ben-Zvi, Ilan [Setauket, NY

    2009-10-13

    An electron gun for generating an electron beam is provided, which includes a secondary emitter. The secondary emitter includes a non-contaminating negative-electron-affinity (NEA) material and emitting surface. The gun includes an accelerating region which accelerates the secondaries from the emitting surface. The secondaries are emitted in response to a primary beam generated external to the accelerating region. The accelerating region may include a superconducting radio frequency (RF) cavity, and the gun may be operated in a continuous wave (CW) mode. The secondary emitter includes hydrogenated diamond. A uniform electrically conductive layer is superposed on the emitter to replenish the extracted current, preventing charging of the emitter. An encapsulated secondary emission enhanced cathode device, useful in a superconducting RF cavity, includes a housing for maintaining vacuum, a cathode, e.g., a photocathode, and the non-contaminating NEA secondary emitter with the uniform electrically conductive layer superposed thereon.

  20. Heat load of a P-doped GaAs photocathode in SRF electron gun

    International Nuclear Information System (INIS)

    Wang, E.; Ben-Zvi, I.; Kewisch, J.; Burrill, A.; Rao, T.; Wu, Q.; Jain, A.; Gupta, R.; Holmes, D.

    2010-01-01

    Many efforts were made over the last decades to develop a better polarized electron source for the high energy physics. Several laboratories operate DC guns with the Gallium-Arsenide photo-cathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved using a Superconducting RF electron gun, which delivers beams of higher brightness than DC guns does, because the field gradient at the cathode is higher. SRF guns with metal cathodes and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since the cathode will be normal conducting, the problem about the heat load stemming from the cathode arises. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and the verification by measuring the quality factor of the gun with and without cathode.

  1. Design, construction and measurements of an alpha magnet as a solution for compact bunch compressor for the electron beam from Thermionic RF Gun

    Science.gov (United States)

    Rajabi, A.; Jazini, J.; Fathi, M.; Sharifian, M.; Shokri, B.

    2018-03-01

    The beam produced by a thermionic RF gun has wide energy spread that makes it unsuitable for direct usage in photon sources. Here in the present work, we optimize the extracted beam from a thermionic RF gun by a compact economical bunch compressor. A compact magnetic bunch compressor (Alpha magnet) is designed and constructed. A comparison between simulation results and experimental measurements shows acceptable conformity. The beam dynamics simulation results show a reduction of the energy spread as well as a compression of length less than 1 ps with 2.3 mm-mrad emittance.

  2. Electron Beam Energy Compensation by Controlling RF Pulse Shape

    CERN Document Server

    Kii, T; Kusukame, K; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.

  3. Design of RF chopper system for improving beam quality in FEL injector with thermionic gun

    International Nuclear Information System (INIS)

    Chen, Q.; Qin, B.; Tan, P.; Hu, T.; Pei, Y.; Zhang, F.

    2014-01-01

    For a linac-based Free Electron Laser (FEL), good beam quality largely contributes to the success of the final radiation. An imperfection confronted with the HUST THz-FEL facility is the long beam tail that emerges in the electron gun and exists through the whole beam line. This paper proposes to deploy a chopper system after the electron gun to truncate the beam tails before they enter into the linac. Physical dimensions of the chopper cavity are discussed in detail and we have developed and derived new analytical expressions applying to all frequencies for the optimal design. Also, technical issues of the cavity are considered. Beam dynamic simulation is performed to examine the truncation effect and the results show that more than 78% of the beam tail can be removed effectively, while preserving the emittance and energy spread in acceptable level

  4. Low Emittance Guns for the ILC Polarized Electron Beam

    International Nuclear Information System (INIS)

    Clendenin, J. E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R. E.; Maruyama, T.; Miller, R. H.; Wang, J. W.; Zhou, F.

    2007-01-01

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of ≥200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while ≥500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns

  5. Low Emittance Guns for the ILC Polarized Electron Beam

    International Nuclear Information System (INIS)

    Clendenin, J.E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R.E.; Maruyama, T.; Miller, R.H.; Wang, J.W.; Zhou, F.; SLAC

    2006-01-01

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of (ge)200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while (ge)500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns

  6. ORELA electron guns

    International Nuclear Information System (INIS)

    Christian, O.W.; Lewis, T.A.

    1981-09-01

    The most recent information concerning the production and performance of ORELA electron guns is presented. Included are descriptions of procedures for gun fabrication, cathode conditioning and high voltage processing. Highlights of the performance characteristics are also included

  7. TREDI: fully 3D beam dynamics simulation of RF guns, bendings and FELs

    CERN Document Server

    Giannessi, L; Quattromini, M

    1999-01-01

    We describe a three-dimensional code modelling the propagation of charged beams in accelerator devices. The inclusion of space charge fields is taken into account by means of the Lienard-Wiechert retarded potentials. As an illustration of the capabilities of the program, the results of a simulation are given that, describe the beam dynamics from the cathode to the undulator through the whole accelerating system. Evidence of bunching in the undulator, as an indication of SASE is observed.

  8. Status and future prospects of SRF gun developments

    International Nuclear Information System (INIS)

    Teichert, Jochen

    2006-01-01

    While the concepts of DC and normal-conducting photo-injectors are well proofed, the SRF gun development still possesses a high risk. Challenges are the thermal and contaminant isolation needed between the cathode and superconducting cavity, the choice of the right photocathode and its life time, the difficulty of coupling high-average power into the gun, and beam excitation of higher order cavity modes. But in combination with SRF linacs, the SRF guns are the best solution for high current and CW operation. Thus, several R and D projects of SRF gun have been launched. The talk will give an overview of the history and progress of the SRF gun development. In more detail the technical concept, performance, and status of the Rossendorf superconducting RF gun project, a collaboration of BESSY, DESY, MBI and FZR, will be presented. (author)

  9. Transverse-emittance measurements on an S-band photocathode RF electron gun

    CERN Document Server

    Schmerge, J F; Clendenin, J E; Decker, Franz Josef; Dowell, D H; Gierman, S M; Limborg, C G; Murphy, B F

    2002-01-01

    Proposed fourth-generation light sources using SASE FELs to generate short pulse, coherent, X-rays require demonstration of high brightness electron sources. The gun test facility at SLAC was built to test high brightness sources for the proposed linac coherent light source at SLAC. The transverse-emittance measurements are made at nearly 30 MeV by measuring the spot size on a YAG screen using the quadrupole scan technique. The emittance was measured to vary from 1 to 3.5 mm mrad as the charge is increased from 50 to 350 pC using a laser pulse width of 2 ps FWHM. The measurements are in good agreement with simulation results using the LANL version of PARMELA.

  10. Heat load of a GaAs photocathode in an SRF electron gun

    International Nuclear Information System (INIS)

    Wang Erdong; Zhao Kui; Jorg Kewisch; Ilan Ben-Zvi; Andrew Burrill; Trivini Rao; Wu Qiong; Animesh Jain; Ramesh Gupta; Doug Holmes

    2011-01-01

    A great deal of effort has been made over the last decades to develop a better polarized electron source for high energy physics. Several laboratories operate DC guns with a gallium arsenide photocathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved by using a superconducting radio frequency (SRF) electron gun, which delivers beams of a higher brightness than that from DC guns because the field gradient at the cathode is higher. SRF guns with metal and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since a bulk gallium arsenide (GaAs) photocathode is normal conducting, a problem arises from the heat load stemming from the cathode. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and verification by measuring the quality factor of the gun with and without the cathode at 2 K. We simulate heat generation and flow from the GaAs cathode using the ANSYS program. By following the findings with the heat load model, we designed and fabricated a new cathode holder (plug) to decrease the heat load from GaAs. (authors)

  11. Progress of the Rossendorf SRF Gun Project

    CERN Document Server

    Teichert, J; Büttig, H; Janssen, D; Lehnert, U; Michel, P; Möller, K; Murcek, P; Schneider, C; Schurig, R; Staufenbiel, F; Xiang, R

    2005-01-01

    A superconducting rf photo electron injector (SRF gun) is under development at the Forschungszentrum Rossendorf. The project aims at several issues: improvement of the beam quality for the ELBE superconducting electron linac, demonstration of feasibility of this gun type, investigation of critical components, and parameter studies for future application (BESSY-FEL, 4GLS). In 2005, a substantial progress has been made. The two 3.5-cell niobium cavities for the gun have been delivered from the company ACCEL. The main parts for gun cryostat like vacuum vessel, cryogenic and magnetic shields are ready. Test benches for the cathode cooling system and the cavity tuner are being assembled. The photo cathode preparation lab has been arranged, and the diagnostic beam line has been designed (see T. Kamps et al., this conference). After delivering the gun cavities, their rf properties are being measured at room temperature and the warm tuning is being carried out. The set-up for this treatment and measurement as well as...

  12. High-Fidelity RF Gun Simulations with the Parallel 3D Finite Element Particle-In-Cell Code Pic3P

    Energy Technology Data Exchange (ETDEWEB)

    Candel, A; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Schussman, G.; Ko, K.; /SLAC

    2009-06-19

    SLAC's Advanced Computations Department (ACD) has developed the first parallel Finite Element 3D Particle-In-Cell (PIC) code, Pic3P, for simulations of RF guns and other space-charge dominated beam-cavity interactions. Pic3P solves the complete set of Maxwell-Lorentz equations and thus includes space charge, retardation and wakefield effects from first principles. Pic3P uses higher-order Finite Elementmethods on unstructured conformal meshes. A novel scheme for causal adaptive refinement and dynamic load balancing enable unprecedented simulation accuracy, aiding the design and operation of the next generation of accelerator facilities. Application to the Linac Coherent Light Source (LCLS) RF gun is presented.

  13. Upgrade possibilities for continuous wave rf electron guns based on room-temperature very high frequency technology

    Science.gov (United States)

    Sannibale, F.; Filippetto, D.; Johnson, M.; Li, D.; Luo, T.; Mitchell, C.; Staples, J.; Virostek, S.; Wells, R.; Byrd, J. M.

    2017-11-01

    The past decade was characterized by an increasing scientific demand for extending towards higher repetition rates (MHz class and beyond) the performance of already operating lower repetition rate accelerator-based instruments such as x-ray free electron lasers (FELs) and ultrafast electron diffraction (UED) and microscopy (UEM) instruments. Such a need stimulated a worldwide spread of a vibrant R&D activity targeting the development of high-brightness electron sources capable of operating at these challenging rates. Among the different technologies pursued, rf guns based on room-temperature structures resonating in the very high frequency (VHF) range (30-300 MHz) and operating in continuous wave successfully demonstrated in the past few years the targeted brightness and reliability. Nevertheless, recently proposed upgrades for x-ray FELs and the always brightness-frontier applications such as UED and UEM are now requiring a further step forward in terms of beam brightness in electron sources. In this paper, we present a few possible upgrade paths that would allow one to extend, in a relatively simple and cost-effective way, the performance of the present VHF technology to the required new goals.

  14. THz and Sub-THz Capabilities of a Table-Top Radiation Source Driven by an RF Thermionic Electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Alexei V.; Agustsson, R.; Boucher, S.; Campese, Tara; Chen, Y.C.; Hartzell, Josiah J.; Jocobson, B.T.; Murokh, A.; O' Shea, F.H.; Spranza, E.; Berg, W.; Borland, M.; Dooling, J. C.; Erwin, L.; Lindberg, R. R.; Pasky, S.J.; Sereno, N.; Sun, Y.; Zholents, A.

    2017-06-01

    Design features and experimental results are presented for a sub-mm wave source [1] based on APS RF thermionic electron gun. The setup includes compact alpha-magnet, quadrupoles, sub-mm-wave radiators, and THz optics. The sub-THz radiator is a planar, oversized structure with gratings. Source upgrade for generation frequencies above 1 THz is discussed. The THz radiator will use a short-period undulator having 1 T field amplitude, ~20 cm length, and integrated with a low-loss oversized waveguide. Both radiators are integrated with a miniature horn antenna and a small ~90°-degree in-vacuum bending magnet. The electron beamline is designed to operate different modes including conversion to a flat beam interacting efficiently with the radiator. The source can be used for cancer diagnostics, surface defectoscopy, and non-destructive testing. Sub-THz experiment demonstrated a good potential of a robust, table-top system for generation of a narrow bandwidth THz radiation. This setup can be considered as a prototype of a compact, laser-free, flexible source capable of generation of long trains of Sub-THz and THz pulses with repetition rates not available with laser-driven sources.

  15. Experience with a radio frequency gun on the SSRL Injector Linac

    International Nuclear Information System (INIS)

    Weaver, J.N.; Genin, R.D.; Golceff, P.; Morales, H.; Sebek, J.

    1993-04-01

    A-SSRL/Varian-Associates-built, one-and-a-half cavity microwave, thermionic-cathode gun has operated on the SSRL Injector Linac reliably without changing the cathode for over 10,000 hours, with no significant decrease in emission. Thus, for a pulsed electron beam, with a maximum of 0.5 A peak at 2 to 3 MeV from a 3.5 MW peak rf pulse of 2 μs pulse width at 10 pps, the apparent but small amount of back bombardment of the cathode has been tolerable. Use of a bunch-compression alpha magnet and a stripline chopper after the gun produces the required S-band 3 to 5 microbunches of electrons for injection into a standard 10-m-long linac and on into a booster synchrotron, which in turn is used to fill SPEAR. Component limitations and operating characteristics of the gun and the linac's rf system are discussed

  16. Back bombardment for dispenser and lanthanum hexaboride cathodes

    Directory of Open Access Journals (Sweden)

    Mahmoud Bakr

    2011-06-01

    Full Text Available The back bombardment (BB effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC and lanthanum hexaboride (LaB_{6} thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6  μs duration, the DC cathode experiences a large change in the temperature compared with LaB_{6}, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  17. Activation Layer Stabilization of High Polarization Photocathodes in Sub-Optimal RF Gun Environments

    Energy Technology Data Exchange (ETDEWEB)

    Gregory A. Mulhollan

    2010-11-16

    Specific activation recipes for bulk, 100 nm thick MBE grown and high polarization III-V photocathode material have been developed which mitigate the effects of exposure to background gasses. Lifetime data using four representative gasses were acquired for bulk GaAs, 100 nm unstrained GaAs and strained superlattice GaAs/GaAsP, all activated both with Cs and then Cs and Li (bi-alkali). Each photoemitter showed marked resilience improvement when activated using the bi-alkali recipe compared to the standard single alkali recipe. A dual alkali activation system at SLAC was constructed, baked and commissioned with the purpose of performing spin-polarization measurements on electrons emitted from the bi-alkali activated surfaces. An end station at SSRL was configured with the required sources for energy resolved photoemission measurements on the bi-alkali activated and CO2 dosed surfaces. The bi-alkali recipes were successfully implemented at SLAC/SSRL. Measurements at SLAC of the photoelectron spin-polarization from the modified activation surface showed no sign of a change in value compared to the standard activated material, i.e., no ill effects. Analysis of photoemission data indicates that the addition of Li to the activation layer results in a multi-layer structure. The presence of Li in the activation layer also acts as an inhibitor to CO2 absorption, hence better lifetimes in worse vacuum were achieved. The bi-alkali activation has been tested on O2 activated GaAs for comparison with NF3 activated surfaces. Comparable resilience to CO2 exposure was achieved for the O2 activated surface. An RF PECVD amorphous silicon growth system was modified to allow high temperature heat cleaning of GaAs substrates prior to film deposition. Growth versus thickness data were collected. Very thin amorphous silicon germanium layers were optimized to exhibit good behavior as an electron emitter. Growth of the amorphous silicon germanium films on the above substrates was fine tuned

  18. Laser deposition of CN.sub.x./sub. films combined with RF and hollow cathode discharges

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Lančok, Ján; Jastrabík, Lubomír; Soukup, Ladislav; Šimečková, Marta; Zelinger, Z.

    1999-01-01

    Roč. 9, - (1999), s. 303-305 Institutional research plan: CEZ:A02/98:Z1-010-914 Keywords : laser deposition * carbon nitride films * radiofrequency discharge * hollow cathode discharge * optical emission spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism

  19. Investigations and Applications of Field- and Photo-emitted Electron Beams from a Radio Frequency Gun

    Energy Technology Data Exchange (ETDEWEB)

    Panuganti, SriHarsha [Northern Illinois Univ., DeKalb, IL (United States)

    2015-08-01

    Production of quality electron bunches using e cient ways of generation is a crucial aspect of accelerator technology. Radio frequency electron guns are widely used to generate and rapidly accelerate electron beams to relativistic energies. In the current work, we primarily study the charge generation processes of photoemission and eld emission inside an RF gun installed at Fermilab's High Brightness Electron Source Laboratory (HBESL). Speci cally, we study and characterize second-order nonlinear photoemission from a Cesium Telluride (Cs2Te) semiconductor photocathode, and eld emission from carbon based cathodes including diamond eld emission array (DFEA) and carbon nanotube (CNT) cathodes located in the RF gun's cavity. Finally, we discuss the application experiments conducted at the facility to produce soft x-rays via inverse Compton scattering (ICS), and to generate uniformly lled ellipsoidal bunches and temporally shaped electron beams from the Cs2Te photocathode.

  20. Characterization of Cs-Sb cathodes for high charge RF photoinjectors

    CERN Document Server

    AUTHOR|(CDS)2082505; Beghi, Marco

    Future accelerators such as CLIC (Compact LInear Collider), require high brightness electron beams that could be produced with a photoinjector (laser-driven electron source). Cs2Te photocathodes in combination with ultra-violet (UV) laser beams are currently used in many photoinjector facilities, but requirements to the electron sources for future accelerators like CLIC are more demanding. The main challenge for the CLIC drive beam photoinjector is to achieve high bunch charges (8.4 nC), high bunch repetition rates (500 MHz) within long trains (140 s) and with suciently long cathode lifetimes. In particular the laser pulse energy in UV, for such long pulse trains, is currently limited due to a degradation of the beam quality during the 4th harmonic frequency conversion process. Using the 2nd harmonic (green laser beam), provided it is matched with a low photoemission threshold photocathode material, would overcome this limitation. Cesium antimonide (Cs3Sb), being a photoemissive material in the visible range,...

  1. ION GUN

    Science.gov (United States)

    Dandl, R.A.

    1961-10-24

    An ion gun is described for the production of an electrically neutral ionized plasma. The ion gun comprises an anode and a cathode mounted in concentric relationship with a narrow annulus between. The facing surfaces of the rear portions of the anode and cathode are recessed to form an annular manifold. Positioned within this manifold is an annular intermediate electrode aligned with the an nulus between the anode and cathode. Gas is fed to the manifold and an arc discharge is established between the anode and cathode. The gas is then withdrawn from the manifold through the annulus between the anode and cathode by a pressure differential. The gas is then ionized by the arc discharge across the annulus. The ionized gas is withdrawn from the annulus by the combined effects of the pressure differential and a collimating magnetic field. In a 3000 gauss magnetic field, an arc voltage of 1800 volts, and an arc current of 0.2 amp, a plasma of about 3 x 10/sup 11/ particles/cc is obtained. (AEC)

  2. Engineering Design and Fabrication of an Ampere-Class Superconducting Photocathode Electron Gun

    International Nuclear Information System (INIS)

    Ben-Zvi, I.

    2008-01-01

    Over the past three years, Advanced Energy Systems and Brookhaven National Laboratory (BNL) have been collaborating on the design of an Ampere- class superconducting photocathode electron gun. BNL performed the physics design of the overall system and RF cavity under prior programs. Advanced Energy Systems (AES) is currently responsible for the engineering design and fabrication of the electron gun under contract to BNL. We will report on the engineering design and fabrication status of the superconducting photocathode electron gun. The overall configuration of the cryomodule will be reviewed. The layout of the hermitic string, space frame, shielding package, and cold mass will be discussed. The engineering design of the gun cavity and removable cathode will be presented in detail and areas of technical risk will be highlighted. Finally, the fabrication sequence and fabrication status of the gun cavity will be discussed

  3. Design of a high charge (10 - 100 nC) and short pulse (2 - 5 ps) rf photocathode gun for wakefield acceleration

    International Nuclear Information System (INIS)

    Gai, W.

    1998-01-01

    In this paper we present a design report on a 1-1/2 cell, L Band RF photocathode gun that is capable of generating and accelerating electron beams with peak currents >10 kA. We have performed simulation for bunch intensities in the range of 10-100 nC with peak axial electrical field at the photocathode of 30-100 MV/m. Unlike conventional short electron pulse generation, this design does not require magnetic pulse compression. Based on numerical simulations using SUPERFISH and PARMELA, this design will produce 20-100 nC beam at 18 MeV with rms bunch length 0.6-1.25 mm and normalized transverse emittance 30-108 mm mrad. Applications of this beam for wakefield acceleration is also discussed

  4. A novel scaling law relating the geometrical dimensions of a photocathode radio frequency gun to its radio frequency properties

    Science.gov (United States)

    Lal, Shankar; Pant, K. K.; Krishnagopal, S.

    2011-12-01

    Developing a photocathode RF gun with the desired RF properties of the π-mode, such as field balance (eb) ˜1, resonant frequency fπ = 2856 MHz, and waveguide-to-cavity coupling coefficient βπ ˜1, requires precise tuning of the resonant frequencies of the independent full- and half-cells (ff and fh), and of the waveguide-to-full-cell coupling coefficient (βf). While contemporary electromagnetic codes and precision machining capability have made it possible to design and tune independent cells of a photocathode RF gun for desired RF properties, thereby eliminating the need for tuning, access to such computational resources and quality of machining is not very widespread. Therefore, many such structures require tuning after machining by employing conventional tuning techniques that are iterative in nature. Any procedure that improves understanding of the tuning process and consequently reduces the number of iterations and the associated risks in tuning a photocathode gun would, therefore, be useful. In this paper, we discuss a method devised by us to tune a photocathode RF gun for desired RF properties under operating conditions. We develop and employ a simple scaling law that accounts for inter-dependence between frequency of independent cells and waveguide-to-cavity coupling coefficient, and the effect of brazing clearance for joining of the two cells. The method has been employed to successfully develop multiple 1.6 cell BNL/SLAC/UCLA type S-band photocathode RF guns with the desired RF properties, without the need to tune them by a tiresome cut-and-measure process. Our analysis also provides a physical insight into how the geometrical dimensions affect the RF properties of the photo-cathode RF gun.

  5. In situ cleaning of metal cathodes using a hydrogen ion beam

    Directory of Open Access Journals (Sweden)

    D. H. Dowell

    2006-06-01

    Full Text Available Metal photocathodes are commonly used in high-field rf guns because they are robust, straightforward to implement, and tolerate relatively poor vacuum compared to semiconductor cathodes. However, these cathodes have low quantum efficiency (QE even at UV wavelengths, and still require some form of cleaning after installation in the gun. A commonly used process for improving the QE is laser cleaning. In this technique the UV-drive laser is focused to a small diameter close to the metal’s damage threshold and then moved across the surface to remove contaminants. This method does improve the QE, but can produce nonuniform emission and potentially damage the cathode. Ideally, an alternative process which produces an atomically clean, but unaltered, surface is needed. In this paper we explore using a hydrogen ion (H-ion beam to clean a copper cathode. We describe QE measurements over the wavelength range of interest as a function of integrated exposure to an H-ion beam. We also describe the data analysis to obtain the work function and derive a formula of the QE for metal cathodes. Our measured work function for the cleaned sample is in good agreement with published values, and the theoretical QE as a function of photon wavelength is in excellent agreement with the cleaned copper experimental results. Finally, we propose an in situ installation of an H-ion gun compatible with existing s-band rf guns.

  6. Sources of Emittance in RF Photocathode Injectors

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-12-11

    Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and applied science. One important beam technology for both is the electron source which, for many of these instruments, is the photocathode RF gun. The invention of the photocathode gun and the concepts of emittance compensation and beam matching in the presence of space charge and RF forces have made these high-quality beams possible. Achieving even brighter beams requires a taking a finer resolution view of the electron dynamics near the cathode during photoemission and the initial acceleration of the beam. In addition, the high brightness beam is more sensitive to degradation by the optical aberrations of the gun’s RF and magnetic lenses. This paper discusses these topics including the beam properties due to fundamental photoemission physics, space charge effects close to the cathode, and optical distortions introduced by the RF and solenoid fields. Analytic relations for these phenomena are derived and compared with numerical simulations.

  7. New method for generating linear transfer matrices through combined rf and solenoid fields

    Science.gov (United States)

    Gulliford, Colwyn; Bazarov, Ivan

    2012-02-01

    We present a new method for computing the transverse transfer matrix for superimposed axisymmetric rf and solenoid field maps. The algorithm constructs the transfer matrix directly from one-dimensional rf and solenoid field maps without computing numerical derivatives or eigenfunction expansions of the field map data. In addition, this method accurately describes the dynamics of low energy particles starting from a solenoid-immersed cathode, allowing the method to simulate transport through both rf and electrostatic guns. Comparison of particle tracking with the transfer matrix, and direct integration of the equations of motion through several field setups, shows excellent agreement between the two methods.

  8. New method for generating linear transfer matrices through combined rf and solenoid fields

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2012-02-01

    Full Text Available We present a new method for computing the transverse transfer matrix for superimposed axisymmetric rf and solenoid field maps. The algorithm constructs the transfer matrix directly from one-dimensional rf and solenoid field maps without computing numerical derivatives or eigenfunction expansions of the field map data. In addition, this method accurately describes the dynamics of low energy particles starting from a solenoid-immersed cathode, allowing the method to simulate transport through both rf and electrostatic guns. Comparison of particle tracking with the transfer matrix, and direct integration of the equations of motion through several field setups, shows excellent agreement between the two methods.

  9. Indirect method of measuring changes of EM field in RF-gun cavity for XFEL accelerator (Pośrednia metoda pomiaru zmian pola we wnęce działa elektronowego akceleratora XFEL)

    CERN Document Server

    Pozniak, K; Zabolotny, W; Koehler, W; Stephan, F; Simrock, S

    2009-01-01

    In the paper an RF-gun control system is described. Difficulties caused by the impossibility to observe directly the field gradient are mentioned. Calibration nd measurement procedure is discussed. A mathematical model, which provides a way to calculate the desired signal from the indirect measurements is developed and analyzed. This model is supported by both measurements and simulations discussed in the final part of the paper. Research done with participation of Ph.D. students.

  10. Development of thin film cathodes for lithium-ion batteries in the material system Li–Mn–O by r.f. magnetron sputtering

    International Nuclear Information System (INIS)

    Fischer, J.; Adelhelm, C.; Bergfeldt, T.; Chang, K.; Ziebert, C.; Leiste, H.; Stüber, M.; Ulrich, S.; Music, D.; Hallstedt, B.; Seifert, H.J.

    2013-01-01

    Today most commercially available lithium ion batteries are still based on the toxic and expensive LiCoO 2 as a standard cathode material. However, lithium manganese based cathode materials are cheaper and environmentally friendlier. In this work cubic-LiMn 2 O 4 spinel, monoclinic-Li 2 MnO 3 and orthorhombic-LiMnO 2 thin films have been synthesized by non-reactive r.f. magnetron sputtering from two ceramic targets (LiMn 2 O 4 , LiMnO 2 ) in a pure argon discharge. The deposition parameters, namely target power and working gas pressure, were optimized in a combination with a post deposition heat treatment with respect to microstructure and electrochemical behavior. The chemical composition was determined using inductively coupled plasma optical emission spectroscopy and carrier gas hot extraction. The films' crystal structure, phase evolution and morphology were investigated by X-ray diffraction, micro Raman spectroscopy and scanning electron microscopy. Due to the fact that these thin films consist of the pure active material without any impurities, such as binders or conductive additives like carbon black, they are particularly well suited for measurements of the intrinsic physical properties, which is essential for fundamental understanding. The electrochemical behavior of the cubic and the orthorhombic films was investigated by galvanostatic cycling in half cells against metallic lithium. The cubic spinel films exhibit a maximum specific capacity of ∼ 82 mAh/g, while a specific capacity of nearly 150 mAh/g can be reached for the orthorhombic counterparts. These films are promising candidates for future all solid state battery applications. - Highlights: ► Synthesis of 3 Li–Mn–O structures by one up-scalable thin film deposition method ► Formation of o-LiMnO 2 by r.f. magnetron sputtering in combination with post-annealing ► Discharge capacity with o-LiMnO 2 cathodes twice as high as for c-LiMn 2 O 4 ► Thin film deposition of m-Li 2 MnO 3 and

  11. ELECTRON GUN

    Science.gov (United States)

    Christofilos, N.C.; Ehlers, K.W.

    1960-04-01

    A pulsed electron gun capable of delivering pulses at voltages of the order of 1 mv and currents of the order of 100 amperes is described. The principal novelty resides in a transformer construction which is disposed in the same vacuum housing as the electron source and accelerating electrode structure of the gun to supply the accelerating potential thereto. The transformer is provided by a plurality of magnetic cores disposed in circumferentially spaced relation and having a plurality of primary windings each inductively coupled to a different one of the cores, and a helical secondary winding which is disposed coaxially of the cores and passes therethrough in circumferential succession. Additional novelty resides in the disposition of the electron source cathode filament input leads interiorly of the transformer secondary winding which is hollow, as well as in the employment of a half-wave filament supply which is synchronously operated with the transformer supply such that the transformer is pulsed during the zero current portions of the half-wave cycle.

  12. Gridded thermionic gun and integral superconducting ballistic bunch compression cavity

    Energy Technology Data Exchange (ETDEWEB)

    Schultheiss, Thomas [Advanced Energy Systems, Inc., Medford, NY (United States)

    2015-11-16

    Electron-Ion colliders such as the Medium energy Electron Ion Collider (MEIC) being developed by JLAB require high current electrons with low energy spread for electron cooling of the collider ring. Accelerator techniques for improving bunch charge, average current, emittance, and energy spread are required for Energy Recovery Linacs (ERLs) and Circulator Rings (CR) for next generation colliders for nuclear physics experiments. Example candidates include thermionic-cathode electron guns with RF accelerating structures. Thermionic cathodes are known to produce high currents and have excellent lifetime. The success of the IR and THz Free-Electron Laser (FEL) designed and installed by Advanced Energy Systems at the Fritz Haber Institute (FHI) of the Max Planck Society in Berlin [1,2] demonstrates that gridded thermionic cathodes and rf systems be considered for next generation collider technology. In Phase 1 Advanced Energy Systems (AES) developed and analyzed a design concept using a superconducting cavity pair and gridded thermionic cathode. Analysis included Beam Dynamics and thermal analysis to show that a design of this type is feasible. The latest design goals for the MEIC electron cooler were for electron bunches of 420 pC at a frequency of 952.6 MHz with a magnetic field on the cathode of 2kG. This field magnetizes the beam imparting angular momentum that provides for helical motion of the electrons in the cooling solenoid. The helical motion increases the interaction time and improves the cooling efficiency. A coil positioned around the cathode providing 2kG field was developed. Beam dynamics simulations were run to develop the particle dynamics near the cathode and grid. Lloyd Young added capability to Tstep to include space charge effects between two plates and include image charge effects from the grid. He also added new pepper-pot geometry capability to account for honeycomb grids. These additions were used to develop the beam dynamics for this gun. The

  13. Gun Play

    Science.gov (United States)

    Mechling, Jay

    2008-01-01

    Biology and the particular gun culture of the United States come together to explain the persistent and powerful attraction of American boys to both real guns and toy guns. The 1990s saw adults begin to conflate "the gun problem" with "the boy problem," sparking attempts (largely failed) to banish toy guns from homes and…

  14. Measurement of back-bombardment temperature rise in microwave thermionic electron guns.

    Science.gov (United States)

    Kowalczyk, Jeremy M D; Hadmack, Michael R; Madey, John M J

    2013-08-01

    We describe a simple method to measure the back-bombardment heating temperature rise as a function of time in pulsed microwave thermionic guns using a fast rise-time InGaAs detector and optical pyrometer. Gaining knowledge of the nature of that temperature rise and the corresponding current out of the gun are the first steps in devising a scheme to counteract the back-bombardment heating which lengthens the micropulses, limits the macropulse length, and increases the energy spread of the emitted electron beam. We measured a temperature rise of 59 K in our LaB6 cathode which delivered a peak of 600 mA over a 5 μs RF pulse in our 0.33 MV/cm peak field, 2.856 GHz thermionic electron gun.

  15. Design of the fundamental power coupler and photocathode inserts for the 112MHz superconducting electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Xin, T.; Ben-Zvi, I.; Belomestnykh, S.; Chang, X.; Rao, T.; Skaritka, J.; Wu, Q.; Wang, E.; Liang, X.

    2011-07-25

    A 112 MHz superconducting quarter-wave resonator electron gun will be used as the injector of the Coherent Electron Cooling (CEC) proof-of-principle experiment at BNL. Furthermore, this electron gun can be the testing cavity for various photocathodes. In this paper, we present the design of the cathode stalks and a Fundamental Power Coupler (FPC) designated to the future experiments. Two types of cathode stalks are discussed. Special shape of the stalk is applied in order to minimize the RF power loss. The location of cathode plane is also optimized to enable the extraction of low emittance beam. The coaxial waveguide structure FPC has the properties of tunable coupling factor and small interference to the electron beam output. The optimization of the coupling factor and the location of the FPC are discussed in detail. Based on the transmission line theory, we designed a half wavelength cathode stalk which significantly brings down the voltage drop between the cavity and the stalk from more than 5.6 kV to 0.1 kV. The transverse field distribution on cathode has been optimized by carefully choosing the position of cathode stalk inside the cavity. Moreover, in order to decrease the RF power loss, a variable diameter design of cathode stalk has been applied. Compared to the uniform shape of stalk, this design gives us much smaller power losses in important locations. Besides that, we also proposed a fundamental power coupler based on the designed beam parameters for the future proof-of-principle CEC experiment. This FPC should give a strong enough coupling which has the Q external range from 1.5e7 to 2.6e8.

  16. The ALS Gun Electronics system

    International Nuclear Information System (INIS)

    Lo, C.C.

    1993-05-01

    The ALS Gun Electronics system has been designed to accommodate gun with a custom made socket and high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

  17. Advances in DC photocathode electron guns

    International Nuclear Information System (INIS)

    Dunham, B. M.; Hartmann, P.; Kazimi, R.; Liu, H.; Poelker, B. M.; Price, J. S.; Rutt, P. M.; Schneider, W. J.; Sinclair, C. K.

    1999-01-01

    At Jefferson Lab, a DC photoemission gun using GaAs and GaAs-like cathodes provides a source of polarized electrons for the main accelerator. The gun is required to produce high average current with long operational lifetimes and high system throughput. Recent work has shown that careful control of the parameters affecting cathode lifetime lead to dramatic improvements in source operation. These conditions include vacuum and the related effect of ion backbombardment, and precise control of all of the electrons emitted from the cathode. In this paper, we will review recent results and discuss implications for future photocathode guns

  18. Advances in DC photocathode electron guns

    International Nuclear Information System (INIS)

    Dunham, B.M.; Hartmann, P.; Kazimi, R.; Liu, H.; Poelker, B.M.; Price, J.S.; Rutt, P.M.; Schneider, W.J.; Sinclair, C.K.

    1999-01-01

    At Jefferson Lab, a DC photoemission gun using GaAs and GaAs-like cathodes provides a source of polarized electrons for the main accelerator. The gun is required to produce high average current with long operational lifetimes and high system throughput. Recent work has shown that careful control of the parameters affecting cathode lifetime lead to dramatic improvements in source operation. These conditions include vacuum and the related effect of ion backbombardment, and precise control of all of the electrons emitted from the cathode. In this paper, we will review recent results and discuss implications for future photocathode guns. copyright 1999 American Institute of Physics

  19. Advances in DC photocathode electron guns

    International Nuclear Information System (INIS)

    Dunham M, Bruce; Heartmann, P.; Reza Kazimi; Hongxiu Liu; Poelker, B.M.; Price, J.S.; Rutt, P.M.; Schneider, W.J.; Sinclair K, Charles

    1998-01-01

    At Jefferson Lab, a DC photoemission gun using GaAs and GaAs-like cathodes provides a source of polarized electrons for the main accelerator. The gun is required to produce high average current with long operational lifetimes and high system throughout. Recent work has shown that careful control of the parameters affecting cathode lifetime lead to dramatic improvements in source operation. These conditions include vacuum and the related effect of ion back-bombardment, and precise control of all of the electrons emitted from the cathode. In this paper, the authors will review recent results and discuss implications for future photocathode guns

  20. Arc Plasma Gun With Coaxial Powder Feed

    Science.gov (United States)

    Zaplatynsky, Isidor

    1988-01-01

    Redesigned plasma gun provides improved metallic and ceramic coatings. Particles injected directly through coaxial bore in cathode into central region of plasma jet. Introduced into hotter and faster region of plasma jet.

  1. State-of-the-Art Electron Guns and Injector Designs for Energy Recovery Linacs (ERL)

    CERN Document Server

    Todd, Alan; Ben-Zvi, Ilan; Benson, Stephen V; Blüm, Hans; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Campisi, Isidoro E; Chang, Xiangyun; Christina, Vincent; Cole, Michael; Colestock, Patrick L; Daly, Edward; Douglas, David; Dylla, Fred H; Falletta, Michael; Hahn, Harald; Hernandez-Garcia, Carlos; Hogan, John; Holmes, Douglas; Janssen, Dietmar; Kayran, Dmitry; Kelley, John P; Kewisch, Jorg; Kneisel, Peter; Kurennoy, Sergey; Lewellen, John W; Litvinenko, Vladimir N; Mammosser, John; McIntyre, Gary; Neil, George R; Nguyen, Dinh C; Nicoletti, Tony; Peterson, Ed; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Reass, William; Rees, Daniel; Rimmer, Robert; Rode, Claus; Russell, Steven; Scaduto, Joseph; Schrage, Dale L; Schultheiss, Tom; Sekutowicz, Jacek; Siggins, Tim; Warren Funk, L; Whitlach, Timothy; Wiseman, Mark; Wong, Robert; Wood, Richard L; Wu, Kuo-Chen; Young, Lloyd M; Zaltsman, Alex; Zhao, Yongxiang

    2005-01-01

    A key technology issue of ERL devices for high-power free-electron laser (FEL) and 4th generation light sources is the demonstration of reliable, high-brightness, high-power injector operation. Ongoing programs that target up to 1 Ampere injector performance at emittance values consistent with the requirements of these applications are described. We consider that there are three possible approaches that could deliver the required performance. The first is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. Such a 750 MHz device is being integrated and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility beginning in 2007. The second approach is a high-current normal-conducting RF photoinjector. A 700 MHz gun will undergo thermal test in 2006 at the Los Alamos National Laboratory, which, if successful, when equipped with a suitable cathode, would be capable of 1 Ampere operation. The last option is an SRF gun. A half-cell 703 MHz SRF gun capable of delivering 1.0...

  2. Design and development of a pierce electron gun

    International Nuclear Information System (INIS)

    Bhattacharjee, D.; Tiwari, R.; Nayak, B.; Tillu, A.R.; Jayaprakash, D.; Mishra, R.L.; Mittal, K.C.; Chakravarthy, D.P.; Gantayet, L.M.

    2011-01-01

    An electron gun is designed and developed using the Pierce configuration for the focusing electrode. Simulations were carried out using CST Particle Studio. The Gun is a thermionic type electron gun with indirect heating of the LaB6 cathode. The gun is capable of delivering a beam current of 500 mA at 50 kV with a beam size of less than 3.5 mm. It was tested on the gun test bench. This paper presents the gun design, particle simulations study, testing of the gun on test bench and integration with the ECIL 9 MeV linac. (author)

  3. Plural beam electron gun assembly

    International Nuclear Information System (INIS)

    Stratton, M.G.

    1977-01-01

    The invention relates to a cathode ray tube plural-beam-in-line bi-potential electron gun assembly, having applied beam currents of differing levels, manifests structurally modified gun structures to effect focused beam landings at the screen that are evidenced as substantially equi-sized spots thereby providing improved resolution and brightness of the screen imagery. The structural changes embody modifications of the related focusing and accelerator electrodes of the respective guns to provide a partial telescoping arrangement for effecting the discrete placement, forming and shielding of the final focusing lenses. The three lenses so formed are in different planes in partial overlapping axial relationship

  4. Post-Removal Examination of GTF Cathode #3

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, R.

    2005-01-31

    This photo-cathode (PC), Gun Test Facility (GTF) Cathode No.3, was removed from the GTF injector, after operation, in March, 2003 (report LCLS-TN-03-1). It was examined originally by secondary electron microscopy in October, 2000, after polishing and degreasing, prior to insertion into the GTF injector. Images of the PC prior to insertion into the rf gun and after running are included in this report. The cathode fabrication and preparation steps were: The cathode plate was conventionally-machined at SLAC, using class one OFE copper plate from Klystron Dept stock. A centrally-located ten mm through-hole was produced, and the plate was then cleaned in the SLAC Plating Shop (procedure C01A, no Oxyban). A tuning rod attachment nut was then 35-65 Au/Cu-brazed to the rear of the plate for in-situ attachment to the GTF transfer/tuning rod. A two mm-thick (100) single-crystal ten mm diameter Cu disk-insert was oriented with Laue x-ray diffraction, and Au/Cu-brazed into the hole with Au/Cu. The plate was then polished to smooth flatness by J. Francis, initially using SiC and, finally, 0.25 micron diamond paste. The plate was then solvent-degreased, face-down on teflon edge supports with hot TCE, acetone and ethanol. The cathode surface was then imaged in the SEM and installed into the GTF rf gun. This report covers the surface appearance before and after GTF running. It will address the following: What is the general surface condition as a result of running? What is the distribution of debris and breakdown features? Is breakdown activity enhanced at the braze line or at the voids in the braze line? Has rf heating, although minimal, affected the surface/braze line, perhaps through thermal expansion? And finally, is laser or ion-feedback damage visible at the single crystal center and what is its nature?

  5. Klystron - Space-charge limited flow, guns, Perveance

    International Nuclear Information System (INIS)

    Isagawa, S.

    1999-01-01

    This paper treats Thermionic emission, Cathode as an e - emitter, Space-charge limited effect and 3/2 power law, Perveance, Beam spread due to space charge, Pierce guns, Magnetically immersed guns, Method of gun design including simulations, and Examples, mainly treating E3786, which attendees will operate above 1 MW-CW in a practical exercise course at KEK. (author). 74 refs

  6. In-Situ Cleaning of Metal Cathodes Using a Hydrogen Ion Beam

    CERN Document Server

    Dowell, D H; Kirby, R E; Schmerge, J F

    2005-01-01

    Improving and maintaining the quantum efficiency (qe) of a metal photocathode in an s-band RF gun requires a process for cleaning the surface. In this type of gun, the cathode is typically installed and the system is vacuum baked to ~200°C. If the qe is too low, the cathode is cleaned with the UV-drive laser. While laser cleaning does increase the cathode qe, it requires fluences close to the damage threshold and rastering the small diameter beam, both of which can produce non-uniform electron emission and potentially damage the cathode. This paper investigates the efficacy of a low-energy hydrogen ion beam to produce high-qe metal cathodes. Measurements of the qe vs. wavelength, surface contaminants using x-ray photoelectron spectroscopy and surface roughness were performed on copper samples, and the results showed a significant increase in qe after cleaning with a 1keV hydrogen ion beam. The H-ion beam cleans an area approximately 1cm in diameter and has no effect on the surface roughness while ...

  7. Gun Safety

    Science.gov (United States)

    Many U.S. households have guns, but they can cause harm if not handled properly. Here are some things you can do to keep yourself and ... safe: Teach children that they shouldn't touch guns and that if they see a gun, to ...

  8. Thermal Emittance Measurement of the Cs2Te Photocathode in FZD Superconducting RF

    CERN Document Server

    Xiang, R; Michel, P; Murcek, P; Teichert, J

    2010-01-01

    The thermal emittance of the photocathode is an interesting physical property for the photoinjector, because it decides the minimum emittance the photoinjector can finally achieve. In this paper we will report the latest results of the thermal emittance of the Cs2Te photocathode in FZD Superconducting RF gun. The measurement is performed with solenoid scan method with very low bunch charge and relative large laser spot on cathode, in order to reduce the space charge effect as much as possible, and meanwhile to eliminate the wake fields and the effect from beam halos.

  9. S-Band RF photoinjector as a driver for coherent Cherenkov source

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, A.V., E-mail: asmirnov@radiabeam.com [RadiaBeam Technologies, LLC, 1717 Stewart Street, Santa Monica, CA 90404 (United States); Musumeci, P. [University of California at Los Angeles, Los Angeles, CA, 90095 (United States)

    2013-09-01

    Resonant Cherenkov radiation in capillary slow-wave structures driven by relativistic beams from a low-energy S-band photoelectron gun is considered. The generation of few megaelectron volt, sub-millimeter-sized, sub-ps microbunches is analyzed numerically. Different modes of operation of such an overfocused, high-current-density system with corresponding adaptation of RF photoinjector is discussed including some experimental measurements with beam on-cathode microbunching. Feasibility of generation of high peak power generation at terahertz frequencies is demonstrated with laser pulse multiplexing and photomixing.

  10. Gun Safety (For Kids)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Gun Safety KidsHealth / For Kids / Gun Safety What's in ... from guns outside the home. If You Have Guns in Your Home If your parents keep guns ...

  11. 120 Hz Gun Review

    Energy Technology Data Exchange (ETDEWEB)

    Colby, E.

    2005-01-31

    The review was held at SLAC on September 11 and 12, 2001. Presentations concerning the thermal analysis, mechanical design, integration with the laser and accelerator, general beam dynamics considerations, a load lock mechanism, and symmetric power feed options comprised the review. Slides from these presentations are available elsewhere. The review committee was charged with evaluating the 120 Hz gun design including proposed load lock and power feed options and recommending improvements. Broader evaluation of the injector as a whole (including focusing and diagnostic systems that do no impact the envelope of the gun itself) is expected to be covered in a future review and will not be commented on here. In general, the long operational experience with four generations of s-band RF guns at numerous labs worldwide has led to considerable experience in design, fabrication, and operation aspects, and provides an excellent base on which to design the higher duty factor LCLS injector. While open questions remain on obtaining the design performance from these injectors, the microwave design of the gun has reached a state of relative maturity.

  12. Sanoli Gun

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences. Sanoli Gun. Articles written in Proceedings – Mathematical Sciences. Volume 119 Issue 3 June 2009 pp 275-281. Remarks on some Zero-Sum Theorems · S D Adhikari Sanoli Gun Purusottam Rath · More Details Abstract Fulltext PDF. In the present paper, we give a ...

  13. A 3 GHz photoelectron gun for high beam intensity

    CERN Document Server

    Bossart, Rudolf; Dehler, M; Godot, J C

    1996-01-01

    For the Compact Linear Collider Test Facility (CTF) at CERN a new rf gun with a laser driven photocathode is under construction. The new rf gun will replace the present 11/2 cell gun and will consist of 21/2 cells accelerating the beam to a momentum of 7.0 MeV/c with an electric field strength of 100 MV/m. The strong space-charge forces at low beam energy caused by the high charge density of the electron bunches are contained by radial and longitudinal rf focusing in the gun. The rf gun under construction has been optimized by MAFIA beam simulations for an injector assembly comprising a second accelerating rf structure and an intermediate solenoid magnet correcting the beam divergence of the 21/2 cell gun. The beam loading of the rf gun, by a train of 48 bunches with 21 nC charge each, causes a strong energy decay accompanied by an increase of the flight time for the bunches with lower energy. These effects can be corrected by slightly shifting the acceleration frequency of the gun. The experimental results...

  14. Theoretical approach of the photoinjector exit aperture influence on the wake field driven by an electron beam accelerated in an RF gun of free-electron laser 'ELSA'

    CERN Document Server

    Salah, W

    2000-01-01

    The wake field generated in the cylindrical cavity of an RF photoinjector, by a strongly accelerated electron beam, has been analytically calculated (Salah, Dolique, Nucl. Instr. and Meth. A 437 (1999) 27) under the assumption that the perturbation of the field map by the exit hole is negligible as long as the ratio: exit hole radius/cavity radius is lower than approximately 1/3. Shown experimentally in the different context of a long accelerating structure formed by a sequence of bored pill-box cavity (Figuera et al., Phys. Rev. Lett. 60 (1988) 2144; Kim et al., J. Appl. Phys. 68 (1990) 4942), this often-quoted result must be checked for the wake field map excited in a photo injector cavity. Further, in the latter case, the empirical rule in question can be broken more easily because, due to causality, the cavity radius to be considered is not the physical radius but that of the part of the anode wall around the exit hole reached by the beam electromagnetic influence. We present an analytical treatment of th...

  15. Gun Violence and Gun Control

    OpenAIRE

    Greenberg, Mark; Litman, Harry

    2009-01-01

    This short essay was commissioned by the London Review of Books, but in the end we decided not to publish it, in part because we felt that there were empirical issues that we were not in a position to assess. A longer working paper that develops the argument further and contains supporting material is posted on SSRN under the title "Rethinking Gun Violence." We welcome comments on either paper. The essay takes Joyce Malcolm's Guns and Violence and Jim Jacobs's Can Gun Control Work? as jump...

  16. Gun Control, Gun Ownership, and Suicide Prevention.

    Science.gov (United States)

    Lester, David

    1988-01-01

    Explored relationship between the extent of gun ownership and the strictness of gun control laws to suicide and homicide rates in the nine major geographic regions of the United States. Found gun ownership, rather than the strictness of gun control laws, was the strongest correlate of the rates of suicide and homicide by guns. (Author)

  17. ATA injector-gun calculations

    International Nuclear Information System (INIS)

    Paul, A.C.

    1981-01-01

    ATA is a pulsed, 50 ns 10 KA, 50 MeV linear induction electron accelerator at LLNL. The ETA could be used as an injector for ATA. However the possibility of building a new injector gun for ATA, raised the question as to what changes from the ETA gun in electrode dimensions or potentials, if any, should be considered. In this report the EBQ code results for the four electrode configurations are reviewed and an attempt is made to determine the geometrical scaling laws appropriate to these ETA type gun geometries. Comparison of these scaling laws will be made to ETA operation. The characteristic operating curves for these geometries will also be presented and the effect of washer position determined. It will be shown that emittance growth will impose a limitation on beam current for a given anode potential before the virtual cathode limit is reached

  18. Time dependent formulation of the energy loss by an accelerated intense electron beam just emitted by the cathode of RF-FEL photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Salah, Wa' el [Physics Department, Hashemite University, Zarqa 13115 (Jordan)]. E-mail: wael_salahh@hotmail.com; Coacolo, J.-L. [Institut de Physique Nucleaire d' Orsay, 91406 Orsay Cedex (France); Hallak, A.B. [Physics Department, Hashemite University, Zarqa 13115 (Jordan); Al-Obaid, M. [Physics Department, Hashemite University, Zarqa 13115 (Jordan)

    2006-08-01

    The energy loss by an accelerated electron bunch of a conical shape propagating in the laser-driven RF-photoinjector is expressed in terms of an expansion of the vector and scalar potentials into a series of eigenfunctions of the empty unit 'pill-box' cavity. A versatile and simple analytical formula which can be easily applied to a bunch of any shape is obtained.

  19. Design and performance of high uniformity linear filament electron gun

    International Nuclear Information System (INIS)

    Iqbal, Munawar; Fazal-e-Aleem

    2006-01-01

    We describe new features and results from the previously reported [M. Iqbal et al., Rev. Sci. Instrum. 74, 4616 (2003)] thermionic long (up to 140 mm) cathode, electromagnetically focused electron beam gun. The gun which was tested up to 50 kW (5000 mAx10 kV) achieves power density of 33 kW/cm 2 at the target. The cathode temperature and emission current was uniform over a length of 100 mm of the cathode. The beam density profile along the line cathode strongly relates to the temperature distribution along the line cathode. The gun has a remarkable application in heat treatment of large surface area and to coat large substrate surfaces at much faster evaporation rates with lower cost

  20. Characterization of an Electron Gun for Hollow Electron Beam Collimation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Siqi [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2012-08-01

    Hollow electron beam collimation (HEBC) is a new technique developed to complement conventional beam collimation system to remove beam halo in a controlled fashion. We study the characteristics of the electron gun that produces the hollow electron beam. Cathode yield and beam profile measurements are used to extract information on gun performance. Results of characteristic measurements are presented.

  1. Development of laser heated high current DC electron gun

    International Nuclear Information System (INIS)

    Banerjee, Srutarshi; Bhattacharjee, Dhruva; Kandaswamy, E.; Ghodke, S.R.; Tiwari, Rajnish; Bakhtsingh, R.I.

    2015-01-01

    The paper deals with the development of a Laser heated cathode for Electron Accelerator. The electron gun is meant for Megawatt-class DC Accelerator for Electron Beam Flue Gas Treatment applications. Conventionally, LaB 6 cathode is indirectly heated by tungsten filaments whereas in the newly proposed gun, Laser is utilized for heating. A Nd:YAG Laser is used to heat the LaB 6 cathode to emission temperatures. The characterization of cathode heating at various Laser powers has been carried out. In initial trials, it has been observed that with 125 W of Laser power, the LaB 6 pellet was heated to 1315 ° C. Based on these experimental results, an electron gun rated for 30 kV, 350 mA CW has been designed. The optimization of gun electrode geometry has been done using CST Particle Studio in order to tune the various electron gun parameters. The beam diameter obtained in simulation is 8 mm at 100 mm from the LaB 6 cathode. The perveance obtained is 7.1 x 10 -8 A/V 3/2 . The Laser heated cathode has the advantages of eliminating the magnetic field effects of filament on the electron beam, electrical isolation needed for gun filament power supplies and better electron beam emittances. (author)

  2. Dark current studies on a normal-conducting high-brightness very-high-frequency electron gun operating in continuous wave mode

    Directory of Open Access Journals (Sweden)

    R. Huang

    2015-01-01

    Full Text Available We report on measurements and analysis of a field-emitted electron current in the very-high-frequency (VHF gun, a room temperature rf gun operating at high field and continuous wave (CW mode at the Lawrence Berkeley National Laboratory (LBNL. The VHF gun is the core of the Advanced Photo-injector Experiment (APEX at LBNL, geared toward the development of an injector for driving the next generation of high average power x-ray free electron lasers. High accelerating fields at the cathode are necessary for the high-brightness performance of an electron gun. When coupled with CW operation, such fields can generate a significant amount of field-emitted electrons that can be transported downstream the accelerator forming the so-called “dark current.” Elevated levels of a dark current can cause radiation damage, increase the heat load in the downstream cryogenic systems, and ultimately limit the overall performance and reliability of the facility. We performed systematic measurements that allowed us to characterize the field emission from the VHF gun, determine the location of the main emitters, and define an effective strategy to reduce and control the level of dark current at APEX. Furthermore, the energy spectra of isolated sources have been measured. A simple model for energy data analysis was developed that allows one to extract information on the emitter from a single energy distribution measurement.

  3. One nanosecond pulsed electron gun systems

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1979-02-01

    At SLAC there has been a continuous need for the injection of very short bunches of electrons into the accelerator. Several time-of-flight experiments have used bursts of short pulses during a normal 1.6 micro-second rf acceleration period. Single bunch beam loading experiments made use of a short pulse injection system which included high power transverse beam chopping equipment. Until the equipment described in this paper came on line, the basic grid-controlled gun pulse was limited to a rise time of 7 nanoseconds and a pulse width of 10 nanoseconds. The system described here has a grid-controlled rise time of less than 500 pico-seconds, and a minimum pulse width of less than 1 nanosecond. Pulse burst repetition rate has been demonstrated above 20 MHz during a 1.6 microsecond rf accelerating period. The order-of-magnitude increase in gun grid switching speed comes from a new gun design which minimizes lead inductance and stray capacitance, and also increases gun grid transconductance. These gun improvements coupled with a newly designed fast pulser mounted directly within the gun envelope make possible subnanosecond pulsing of the gun

  4. Growth of cerium oxide thin layers for the manufacture of dosemeters and/or irradiation detectors by magnetron RF cathodic sputtering; Croissance de couches minces d'oxyde de cerium pour la realisation de dosimetres et/ou de detecteurs d'irradiation par pulverisation cathodique RF magnetron

    Energy Technology Data Exchange (ETDEWEB)

    Ta, M.T.; Briand, D.; Guhel, Y.; Bernard, J.; Boudart, B. [Laboratoire Universitaire des Sciences Appliquees de Cherbourg (LUSAC), 50 - Cherbourg (France)

    2007-07-01

    Oxide thin films deposited on silicon substrate are interesting for the manufacture of dosemeters and detectors of gas, humidity, temperature and irradiation. The irradiation dose measurement is required for assessing the risks and advantages of the use of ionizing radiations in fields such as biology, medicine and more generally in all the civil and military nuclear applications. According to literature, cerium oxide seems to be potentially interesting for the manufacture of dosemeters and/or irradiation detectors. The influence of the deposition parameters, such as the inter-electrodes distance, the temperature, the RF power, the work pressure, on the crystalline quality of the CeO{sub 2} layers deposited on a silicon (111) substrate by magnetron RF cathodic sputtering has been studied. All these thin films have been characterized by X-ray diffraction and by Raman spectroscopy. At the present time, studies are carried out on 'flash' annealing in order to improve the crystalline state of the thin layers. The aim is to study the influence of gamma and neutrons irradiations on the electric properties of capacities made of CeO{sub 2} thin films. (O.M.)

  5. Spectrometer gun

    Science.gov (United States)

    Waechter, David A.; Wolf, Michael A.; Umbarger, C. John

    1985-01-01

    A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

  6. 6D Phase Space Measurements at the SLAC Gun Test Facility

    CERN Document Server

    Schmerge, J

    2003-01-01

    Proposed fourth generation light sources using SASE FELs to generate short pulse, coherent X-rays require demonstration of high brightness electron sources. The Gun Test Facility (GTF) at SLAC was built to test high brightness sources for the proposed Linac Coherent Light Source at SLAC. The GTF is composed of an Sband photocathode rf gun with a Cu cathode, emittance compensating solenoid, single 3 m SLAC linac section and e-beam diagnostic section with a UV drive laser system. The longitudinal emittance exiting the gun has been determined by measuring the energy spectrum downstream of the linac as a function of the linac phase. The e-beam pulse width, correlated and uncorrelated energy spread at the linac entrance have been fit to the measured energy spectra using a least square error fitting routine. The fit yields a pulse width of 2.9 ps FWHM for a 4.3 ps FWHM laser pulse width and 2% rms correlated energy spread with 0.07% rms uncorrelated energy spread. The correlated energy spread is enhanced in the lin...

  7. Measurements of copper and cesium telluride cathodes in a radio-frequency photoinjector

    Directory of Open Access Journals (Sweden)

    Eduard Prat

    2015-04-01

    Full Text Available Radio-frequency (rf photoinjectors are commonly used to generate intense bright electron beams for a wide range of applications, most notably as drivers for X-ray Free-Electron Lasers. The photocathode, mounted inside an rf gun and illuminated by a suitable laser, thereby plays a crucial role as the source of the electrons. The intrinsic emittance and the quantum efficiency of the electron source are determined by the properties of the photocathode’s surface material. We present measurements of the intrinsic emittance and the quantum efficiency performed with copper and cesium telluride cathodes in the same rf photoinjector, thus comparing, for the first time, the performance of metal and semiconductor cathodes under the same conditions. Our results are consistent with theoretical expectations and show that the difference in intrinsic emittance for the two types of material is not significant in view of accelerator applications. We conclude that cesium telluride photocathodes provide a much higher quantum efficiency at essentially negligible degradation in beam emittance.

  8. Design and fabrication of a pulsed diode electron gun

    International Nuclear Information System (INIS)

    Mahadevan, S.; Gandhi, M.L.; Nandedkar, R.V.

    2003-01-01

    A pulsed diode electron gun has been designed, fabricated and tested and this will be used for the initial hot testing of the Plane Wave Transformer (PWT) linac. The gun is required to deliver 1 A at 70 kV which works out to a current of 500 mA at 40 kV. The gun geometry is optimized using the Electron Trajectory Program EGUN at a mesh size of 0.2 mm. The beam divergence close to cathode caused by an annular gap of 2 mm between cathode and focusing electrode (FE) is compensated by using a suitable focusing electrode. Important features of the pulsed power supply (40 kV, 500 mA, 2 μsec) developed for testing this gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance. Suitable positioning of cathode with respect to the FE helps in further improving the beam quality

  9. Water gun vs air gun: A comparison

    Science.gov (United States)

    Hutchinson, D.R.; Detrick, R. S.

    1984-01-01

    The water gun is a relatively new marine seismic sound source that produces an acoustic signal by an implosive rather than explosive mechanism. A comparison of the source characteristics of two different-sized water guns with those of conventional air guns shows the the water gun signature is cleaner and much shorter than that of a comparable-sized air gun: about 60-100 milliseconds (ms) for an 80-in3. (1.31-liter (I)) water gun compared with several hundred ms for an 80-in3. (1.31-1) air gun. The source spectra of water guns are richer in high frequencies (>200 Hz) than are those of air guns, but they also have less energy than those of air guns at low frequencies. A comparison between water gun and air gun reflection profiles in both shallow (Long Island Sound)-and deep (western Bermuda Rise)-water settings suggests that the water gun offers a good compromise between very high resolution, limited penetration systems (e.g. 3.5-kHz profilers and sparkers) and the large volume air guns and tuned air gun arrays generally used where significant penetration is required. ?? 1984 D. Reidel Publishing Company.

  10. Generation of multi-branch beam with thermionic gun for the Japan linear collider

    International Nuclear Information System (INIS)

    Naito, T.; Akemoto, M.; Matsumonto, H.; Urakawa, J.; Yoshioka, M.; Akiyama, H.

    1992-01-01

    We report on the development of a thermionic gun that is capable of producing multi-bunch beam to be used at the KEK Accelerator Test Facility for the Japan Linear Collider project. Two types of grid pulse generators have been developed. One is an avalanche pulse generator. A Y-646E cathode was successfully operated to generate double-bunch beam with a pulse width shorter than 700 ps, bunch spacing 1.4 ns, and a peak current 4.3 A. The other grid pulse generator is a fast ECL circuit with an RF power amplifier. Generation of 20-pulse trains with 2.1 ns time spacing has been demonstrated. (Author) 4 refs., 6 figs

  11. Design of a high repetition rate S-band photocathode gun

    International Nuclear Information System (INIS)

    Han Janghui; Cox, Matthew; Huang, Houcheng; Pande, Shivaji

    2011-01-01

    Photocathode RF guns have been developed in many laboratories for generating high quality electron beams for free-electron lasers based on linear accelerators. Such guns can generate electron beams with an exceptionally high peak current as well as a small transverse emittance. Their applications have been recently expanded for ultrafast electron diffraction, coherent terahertz radiation, and X-ray or γ-ray radiation by Compton scattering. In this paper, we design an S-band normal-conducting gun with capabilities of high quality beam generation and high repetition rate operation. The RF design and thermal analysis of the gun cavity and coupler are introduced. Optimal position of the gun focusing solenoid for low emittance beam generation is found by performing particle tracking simulations. Then, the gun system is designed to be able to afford the optimal solenoid position. The cooling-water channel surrounding the gun cavity and coupler is designed and analyzed numerically. The pressure in the gun is simulated with a vacuum model containing the detailed inner structure of the gun. An injector for a free-electron laser application is designed by using this gun and the beam dynamics simulation is shown. A cold test with a prototype gun for confirmation of the RF design is reported. - Highlights: → We design an S-band gun for low emittance beam generation and high repetition rate operation. → The RF design and thermal analysis of the gun cavity and coupler are studied. → An FEL injector is designed by using this gun and the beam dynamics simulation is shown. → A cold test with a prototype gun for confirmation of the RF design is reported.

  12. Heating filament system of a Mig-type electron gun for a 35 GHz, 100 k W gyrotron

    International Nuclear Information System (INIS)

    Patire Junior, H.; Barroso, J.J.; Spassovsky, I.P.; Rossi, J.O.

    1993-01-01

    Cathode temperature tests of a Mig-type electron gun have been performed to determine the temperature of the electron emitting surface as a function of heater voltage and current. The test have been conducted partway through the construction phase of the gun as a means to minimize both the necessary heater input power and to reduce radiating of gun components. (author)

  13. The structural design of an electron gun for an E-beam irradiator

    International Nuclear Information System (INIS)

    Yu Xiaojuan; Wu Xunlei; Jiang Zhenbo; Meng Mingfeng

    2011-01-01

    In this paper, an electron gun for a linac E-beam irradiator is developed with a replaceable cathode and filament. The structure of cathode and filament and the concentric technique, with molds and clamps, are described in detail. The electron gun was assembled with care to reduce the error, and ensure the concentricity of electron gun. The test results indicated a 99.99% pass ratio of the electron beams at 60-65 kV. The electron gun design meets the technical requirement of clients. (authors)

  14. Improved DC Gun and Insulator Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, Michael [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-01-11

    Many user facilities such as synchrotron radiation light sources and free electron lasers rely on DC high voltage photoguns with internal field gradients as high as 10 to 15 MV/m. These high gradients often lead to field emission which poses serious problems for the photocathode used to generate the electron beam and the ceramic insulators used to bias the photocathode at high voltage. Ceramic insulators are difficult to manufacture, require long commissioning times, and have poor reliability, in part because energetic electrons bury themselves in the ceramic causing a buildup of charge and eventual puncture, and also because large diameter ceramics are difficult to braze reliably. The lifetimes of photo cathodes inside high current DC guns exhibiting field emission are limited to less than a hundred hours. Reducing the surface gradients on the metals reduces the field emission, which serves to maintain the required ultrahigh vacuum condition. A novel gun design with gradients around 5 MV/m and operating at 350 kV, a major improvement over existing designs, was proposed that allows for the in-situ replacement of photo cathodes in axially symmetric designs using inverted ceramics. In this project, the existing JLAB CEBAF asymmetric gun design with an inverted ceramic support was modeled and the beam dynamics characterized. An improved structure was designed that reduces the surface gradients and improves the beam optics. To minimize the surface gradients, a number of electrostatic gun designs were studied to determine the optimum configuration of the critical electrodes within the gun structure. Coating experiments were carried out to create a charge dissipative coating for cylindrical ceramics. The phase II proposal, which was not granted, included the design and fabrication of an axially symmetric DC Gun with an inverted ceramic that would operate with less than 5 MV/m at 350 kV and would be designed with an in-situ replaceable photo-cathode.

  15. Gun ownership and social gun culture.

    Science.gov (United States)

    Kalesan, Bindu; Villarreal, Marcos D; Keyes, Katherine M; Galea, Sandro

    2016-06-01

    We assessed gun ownership rates in 2013 across the USA and the association between exposure to a social gun culture and gun ownership. We used data from a nationally representative sample of 4000 US adults, from 50 states and District of Columbia, aged >18 years to assess gun ownership and social gun culture performed in October 2013. State-level firearm policy information was obtained from the Brady Law Center and Injury Prevention and Control Center. One-third of Americans reported owning a gun, ranging from 5.2% in Delaware to 61.7% in Alaska. Gun ownership was 2.25-times greater among those reporting social gun culture (PR=2.25, 95% CI 2.02 to 2.52) than those who did not. In conclusion, we found strong association between social gun culture and gun ownership. Gun cultures may need to be considered for public health strategies that aim to change gun ownership in the USA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  16. Encyclopedia of Gun Control and Gun Rights.

    Science.gov (United States)

    Utter, Glenn H.

    This reference volume provides information on gun control and gun rights, including resources on the debate surrounding the Second Amendment and individuals and organizations focused on gun issues, along with statutes, court cases, events, and publications surrounding this current topic. Highlighted are the important organizations and their…

  17. Gun ownership and social gun culture

    OpenAIRE

    Kalesan, Bindu; Villarreal, Marcos D; Keyes, Katherine M; Galea, Sandro

    2015-01-01

    We assessed gun ownership rates in 2013 across the USA and the association between exposure to a social gun culture and gun ownership. We used data from a nationally representative sample of 4000 US adults, from 50 states and District of Columbia, aged >18 years to assess gun ownership and social gun culture performed in October 2013. State-level firearm policy information was obtained from the Brady Law Center and Injury Prevention and Control Center. One-third of Americans reported owning a...

  18. Keeping Naval Guns Ready

    Science.gov (United States)

    2016-03-01

    and stay aboard until the gun is up. Whatever the case, the goal is to get the gun up fast. Guns With Fast “Pit Crews” Winning in stock- car racing...after firing in a corrosive maritime environment. The original maintenance philosophy was to remove a gun from the ship and send it back to the

  19. The Gun Dispute.

    Science.gov (United States)

    Spitzer, Robert J.

    1999-01-01

    Explores the debate over gun ownership and gun control in the United States, focusing on the historic place of guns in U.S. society. The current national mood is more receptive than ever to restricting and regulating adolescent access to guns in light of recent school shootings. (SLD)

  20. Gun Sales. Firearm Facts.

    Science.gov (United States)

    Duker, Laurie, Ed.

    Minimal federal regulations on firearm sales have facilitated the proliferation of guns, gun owners, and gun dealers in the United States. This fact sheet offers data on the growing number of firearm dealers, the relative ease of obtaining and keeping a license to sell guns from the Federal Bureau of Alcohol, Tobacco, and Firearms, the lack of…

  1. More Guns, More Crime

    OpenAIRE

    Mark Duggan

    2000-01-01

    This paper examines the relationship between gun ownership and crime. Previous research has suffered from a lack of reliable data on gun ownership. I exploit a unique data set to reliably estimate annual gun ownership rates at both the state and the county level during the past two decades. My findings demonstrate that changes in gun ownership are significantly positively related to changes in the homicide rate, with this relationship driven entirely by the impact of gun ownership on murders ...

  2. Upgraded G-optk program for electron gun characterization

    International Nuclear Information System (INIS)

    Nagasao, K.; Takebe, M.; Ushio, W.; Fujita, S.; Ohye, T.; Shimoyama, H.

    2011-01-01

    The generalized trajectory theory (the G-optk program) has been extended in order to make the method applicable to electron guns with curved and/or asymmetric cathodes. The object-image analysis mode has also been added. Enhanced capability of the upgraded G-optk program was demonstrated by applying the program to three electron optical systems: (a) the point cathode gun, (b) the hairpin-type cathode gun, and (c) the LEEM objective lens. The Canonical Mapping Transformation (CMT) diagrams were calculated both by direct ray tracing and by the upgraded G-optk program. In each case, it was found that the upgraded program reproduces well the results obtained by ray tracing. The generalized trajectory method has several advantages over direct ray tracing, such as substantially lighter calculation load and easy interpretation of the calculation results in terms of the optical parameters.

  3. A pulsed electron gun for the Plane Wave Transformer Linac

    CERN Document Server

    Mahadevan, S; Nandedkar, R V

    2003-01-01

    A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 mu perv and the normalized emittance is within 5 pi mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

  4. Non-channel magnetron gun as the electron source for resonance linear accelerator

    International Nuclear Information System (INIS)

    Ivanov, G.M.; Makhnenko, L.A.; Cherenshchikov, S.A.

    1999-01-01

    Studies on the magnetron gun with a cold cathode being part of linear accelerator on the travelling wave are described. Two modes of the gun operation differing by presence of UHF field of the pre-buncher near the gun are observed. In the mode without UHF field the short (about 2 ns) pulses of accelerated electrons with amplitude up to 0.5 A at the gun current up to 20 A were obtained. The presence of UHF field near the gun makes it possible to obtain the beam of higher duration (up to 1.0 μs), but with current up to 20 mA at the accelerator outlet and up to 1 A at the gun outlet. The mechanism of the gun operation is concerned with the secondary-electron current increase and setting self-sustaining secondary emission. Gun characteristics under study are acceptable for the purposes of injection into accelerator [ru

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

    Science.gov (United States)

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

    2013-10-01

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

  6. Development of the Antares electron gun

    International Nuclear Information System (INIS)

    Stine, R.; Leland, W.; Mansfield, C.; Rosocha, L.; Jansen, J.; Gibson, R.; Allen, G.

    1984-01-01

    Antares is the Los Alamos National Laboratory 40-kJ, 1-ns, CO 2 laser system that is now operational. This laser system was developed for the Intertial Confinement Fusion (ICF) program and is beginning target experiments. The distributed circuit modeling, design and operation of the large electron gun developed for the final laser power amplifier are reviewed. This gun is significant because of the large electron current area, 9 m 2 ; the number of emitter blades, 48; the dual cathode current return; and the coaxial geometry and grid control. The gun components and their development are discussed. These include the emitter blades, the coaxial grid (to maintain constant electron current during the 5-μs pulse), the bonded stacked-ring insulator (to electrically insulate the grid/cathode), the Kapton/aluminum electron transmission windows (to provide an interface between gun vacuum and laser gas) and the vacuum shell (operated at a vacuum of 10 -6 torr). A unique pressure diagnostic is also discussed

  7. RF transport

    CERN Document Server

    Choroba, Stefan

    2013-01-01

    This paper deals with the techniques of transport of high-power radiofrequency (RF) power from a RF power source to the cavities of an accelerator. Since the theory of electromagnetic waves in waveguides and of waveguide components is very well explained in a number of excellent text books it will limit itself on special waveguide distributions and on a number of, although not complete list of, special problems which sometimes occur in RF power transportation systems.

  8. Design studies on high current and grid control electron gun

    International Nuclear Information System (INIS)

    Wang Jinnan; Lu Kun; Chi Yunlong; Zhou Zusheng

    2011-01-01

    Electron gun, the source of electrons, is a kind of ultrahigh vacuum device and plays an important role in different kind of accelerators. With the irradiation accelerator demands, describes the design studies on beam optics optimization. The simulation result shows that the beam current is above 5 A with cathode voltage of 80 kV and beam emittance, gun electric field and beam waist radius meet the accelerator needs. The electron gun manufactured and installed in the test stand, the conditioning and test will be done in the near future. (authors)

  9. Therminoic gun control system for the CEBAF injector

    International Nuclear Information System (INIS)

    Pico, R.; Diamond, B.; Fugitt, J.; Bork, R.

    1989-01-01

    The injector for the CEBAF accelerator must produce a high-quality electron beam to meet the overall accelerator specifications. A Hermosa electron gun with a 2 mm-diameter cathode and a control aperture has been chosen as the electron source. This must be controlled over a wide range of operating conditions to meet the beam specifications and to provide flexibility for accelerator commissioning. The gun is controlled using Computer Automated Measurement and Control (CAMAC IEEE-583) technology. The system employs the CAMAC-based control architecture developed at CEBAF. The control system has been tested, and early operating data on the electron gun and the injector beam transport system has been obtained. This system also allows gun parameters to be stored at the operator location, without paralyzing operation. This paper describes the use of this computer system in the control of the CEBAF electron gun. 2 refs., 6 figs., 1 tab

  10. Guns and Violence. Current Controversies.

    Science.gov (United States)

    Kim, Henny H., Ed.

    This book focuses on gun violence and gun control, presenting both sides of arguments about firearms ownership and gun control. Each of five chapters poses a question about gun control and provides answers for both sides of the question. The following essays are included: (1) "Gun Violence Is Becoming an Epidemic" (Bob Herbert); (2) "Gun Violence…

  11. Is Gun Violence Contagious?

    OpenAIRE

    Loeffler, Charles; Flaxman, Seth

    2016-01-01

    Existing theories of gun violence predict stable spatial concentrations and contagious diffusion of gun violence into surrounding areas. Recent empirical studies have reported confirmatory evidence of such spatiotemporal diffusion of gun violence. However, existing tests cannot readily distinguish spatiotemporal clustering from spatiotemporal diffusion. This leaves as an open question whether gun violence actually is contagious or merely clusters in space and time. Compounding this problem, g...

  12. Gun Safety (For Parents)

    Science.gov (United States)

    ... or adult feels suicidal and there is a gun readily available. A family argument gets out of control. A family member or friend is mistaken for an intruder. Remember: The best way to prevent gun injuries is to never keep guns at home ...

  13. High Brightness Injectors Based On Photocathode DC Gun

    International Nuclear Information System (INIS)

    B. Yunn

    2001-01-01

    Sample results of new injector design method based on a photocathode dc gun are presented, based on other work analytically proving the validity of the emittance compensation scheme for the case even when beam bunching is involved. We have designed several new injectors appropriate for different bunch charge ranges accordingly. Excellent beam quality produced by these injectors clearly shows that a photocathode dc gun can compete with a rf gun on an equal footing as the source of an electron beam for the bunch charge ranging up to 2 nano Coulomb (nC). This work therefore elevates a dc gun based injector to the preferred choice for many ongoing high brightness accelerator projects considering the proven operational stability and high average power capability of the dc gun

  14. Rail gun of thermonuclear pellet injection device

    International Nuclear Information System (INIS)

    Matsuda, Ryuichi; Kuribayashi, Shizuma; Oda, Yasutsugu.

    1993-01-01

    A rail gun of a thermonuclear pellet injection device using Lorentz force comprises rails constituted with materials of high melting point/low work function and a gas supply system for supplying low ionization/voltage gases into the rails to convert the gases into plasma armature. The low ionization voltage gases are converted into the plasma armature to decrease the resistance of the plasmas and suppress temperature elevation as Joule's heat and lower plasma temperature. Further, on the surface of the rails on the side of the cathode, since the rails are damaged by collision of positive ions due to voltage lowering, the rails on the side of the cathode are constituted with materials of low work function, as the countermeasure therefore, which facilitates emission of heat electrons from the surface of the cathode. With such procedures, thermal damages to the rail can be reduced. (N.H.)

  15. Development of a Polarized Electron Gun Based on an S-Band PWT Photoinjector

    CERN Document Server

    Clendenin, J E; Yu, D; Newsham, D; Luo, Y; Smirnov, A

    2003-01-01

    An RF polarized electron gun utilizing the unique features of an integrated, plane-wave-transformer (PWT) photoelectron injector [1] is being developed by DULY Research Inc. in collaboration with SLAC. Modifications to a DULY S-band device [2] include: a re-design of the photocathode/RF backplane interface to accommodate a GaAs cathode; change in the design of the vacuum ports to provide 10-11 Torr operation; the inclusion of a load-lock photocathode replacement system to allow for reactivation and cessation of the GaAs photocathode in a vacuum; and alteration of the magnet field coils to make room for the load-lock. The use of a stainless steel outer tank and cooling rods without copper plating may also provide better vacuum performance at the expense of diminished Q factor. The effectiveness of both the standard cooling rods and synthetic diamond heat sinks for disk cooling is investigated for future linear collider applications operating at a rep rate of 180 Hz and a bunch charge of 2 nC.

  16. Design of 120 MW beam power electron gun for high power klystron

    International Nuclear Information System (INIS)

    Zhou Zusheng; Dong Dong

    2005-01-01

    An electron gun was designed and the beam optics for a China-made 50 MW klystron was simulated. The electron gun ceramic cylinder was designed and optimized. The China-made cathode was replaced with an imported one to lessen evaporation and arcing. The high voltage (320 kV) of the cathode was increased to meet the klystron output power demand and a low electric field strength (22.1 kV/mm) electron gun was designed to avoid the high power operation which damaged the ceramic cylinder. The klystron output power was increased and life span extended. (authors)

  17. First beam commissioning at BNL ERL SRF Gun

    Energy Technology Data Exchange (ETDEWEB)

    Xu, W. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Altinbas, Z. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy; Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy; Deonarine, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; DeSanto, L. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Gassner, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Gupta, R. C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hahn, H. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hammons, L. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Ho, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Jamilkoski, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Kankiya, P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Kayran, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Kellerman, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Laloudakis, N. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Lambiase, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Liaw, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Litvinenko, V. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy; Mahler, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Masi, L. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; McIntyre, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Miller, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Philips, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Seda, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Sheehy, B. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Smith, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Rao, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Steszyn, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tallerico, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Than, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tuozollo, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Wang, E. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Weiss, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Wiliniski, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Zaltsman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    The 704 MHz SRF gun successfully generated the first photoemission beam in November of 2014. The configurations of the test and the sub-systems are described.The latest results of SRF commissioning, including the cavity performance, cathode QE measurements, beam current/energy measurements, are presented in the paper.

  18. Development techniques and electron optical studies of high voltage, high current electron guns

    International Nuclear Information System (INIS)

    Rangarajan, L.M.; Mahadevan, S.; Ramamurthi, S.S.

    1992-01-01

    The progress of the electron gun design, limiting to axially symmetric geometries is discussed here with a view to utilise such guns for electron accelerators. The mechanical design features leading to the physical configuration of the gun with stringent tolerances are outlined. Vacuum processing is done at pressures of 1.3x10 -5 Pa. The gun employs W-filament emitter or a cathode pellet with bombarder service. A water cooled compact faraday cup is used to measure the electron current. Electron gun geometries have been studied using the computer programme. The preveance of the gun is 0.7x10 -7 A/Vsup(1.5) at 80 kV. Developmental techniques of such pulsed electron guns are described. (author). 7 refs., 5 figs

  19. Women and Guns. Firearm Facts.

    Science.gov (United States)

    Duker, Laurie, Ed.

    Many gun manufacturers market guns to women claiming a gun can provide protection. Statistics provided in this fact sheet indicate gun ownership may provide a false sense of security that can be fatal, since the greatest threat to a woman comes from the people and guns within her own home. Contrary to "typical" scenarios created by advertisers,…

  20. The drive laser for the APS LEUTL FEL Rf photoinjector

    International Nuclear Information System (INIS)

    Arnold, N.; Koldenhoven, R.; Travish, G.

    1999-01-01

    The APS LEUTL free-electron laser (FEL) is a high-gain, short-wavelength device requiring a high-current, low-emittance beam. An rf photoinjector driven by a laser is used to provide the requisite beam. The drive laser consists of a diode-pumped Nd:Glass oscillator and a chirped pulse amplification (CPA) system consisting of a grating stretcher, a flashlamp-pumped Nd:Glass regenerative amplifier, and a grating compressor. The system generates 4-mj pulses in the R with a pulse length as short as 2 ps FWHM and a repetition rate of 6 Hz. Nonlinear doubling crystals are used to generate fourth-harmonic output of ∼500 microJ in the UV (263 nm), which is required to exceed the work function of the copper cathode in the gun. This paper describes the drive laser as well as the extensive controls implemented to allow for remote operation and monitoring. Performance measurements as well as the operating experience are presented

  1. Measuring current emission and work functions of large thermionic cathodes

    International Nuclear Information System (INIS)

    Fortgang, C.M.

    2001-01-01

    As one component of the nations Stockpile Stewardship program, Los Alamos National Laboratory is constructing a 20 MeV, 2 kA (with a 4 kA upgrade capability), 3ps induction linac for doing x-ray radiography of explosive devices. The linac is one leg of a facility called the Dual-Axis Radiography Hydrodynamic Test Facility (DARHT). The electron gun is designed to operate at 3.2 MV. The gun is a Pierce type design and uses a 6.5' cathode for 2 kA operation and an 8' cathode for 4 kA operation. We have constructed a small facility called the Cathode Test Stand (CTS) to investigate engineering and physics issues regarding large thermionic dispenser-cathodes. In particular, we have looked at the issues of temperature uniformity on the cathode surface and cathode quality as measured by its work function. We have done thermal imaging of both 8' and 6.5' cathodes. Here we report on measurements of the cathode work function, both the average value and how it vanes across the face of the cathode.

  2. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  3. High Brightness Electron Guns for Next-Generation Light Sources and Accelerators

    International Nuclear Information System (INIS)

    H. Bluem; M.D. Cole; J. Rathke; T. Schultheiss; A.M.M. Todd; I. Ben-Zvi; T. Srinivasan-Rao; P. Colestock; D.C. Nguyen; R.L. Wood; L. Young; D. Janssen; J. Lewellen; G. Neil; H.L. Phillips; J.P. Preble

    2004-01-01

    Advanced Energy Systems continues to develop advanced electron gun and injector concepts. Several of these projects have been previously described, but the progress and status of each will be updated. The project closest to completion is an all superconducting RF (SRF) gun, being developed in collaboration with the Brookhaven National Laboratory, that uses the niobium of the cavity wall itself as the photocathode material. This gun has been fabricated and will shortly be tested with beam. The cavity string for a closely-coupled DC gun and SRF cavity injector that is expected to provide beam quality sufficient for proposed ERL light sources and FELs will be assembled at the Jefferson Laboratory later this year. We are also collaboration with Los Alamos on a prototype CW normal-conducting RF gun with similar performance, that will undergo thermal testing in late 2004. Another CW SRF gun project that uses a high quantum efficiency photocathode, similar to the FZ-Rossendorf approach, has just begun. Finally, we will present the RF design and cold test results for a fully axisymmetric, ultra-high-brightness x-band RF gun

  4. Toward a terahertz-driven electron gun

    Science.gov (United States)

    Huang, W. Ronny; Nanni, Emilio A.; Ravi, Koustuban; Hong, Kyung-Han; Fallahi, Arya; Wong, Liang Jie; Keathley, Phillip D.; Zapata, Luis E.; Kärtner, Franz X.

    2015-01-01

    Femtosecond electron bunches with keV energies and eV energy spread are needed by condensed matter physicists to resolve state transitions in carbon nanotubes, molecular structures, organic salts, and charge density wave materials. These semirelativistic electron sources are not only of interest for ultrafast electron diffraction, but also for electron energy-loss spectroscopy and as a seed for x-ray FELs. Thus far, the output energy spread (hence pulse duration) of ultrafast electron guns has been limited by the achievable electric field at the surface of the emitter, which is 10 MV/m for DC guns and 200 MV/m for RF guns. A single-cycle THz electron gun provides a unique opportunity to not only achieve GV/m surface electric fields but also with relatively low THz pulse energies, since a single-cycle transform-limited waveform is the most efficient way to achieve intense electric fields. Here, electron bunches of 50 fC from a flat copper photocathode are accelerated from rest to tens of eV by a microjoule THz pulse with peak electric field of 72 MV/m at 1 kHz repetition rate. We show that scaling to the readily-available GV/m THz field regime would translate to monoenergetic electron beams of ~100 keV. PMID:26486697

  5. Cathode degradation

    Energy Technology Data Exchange (ETDEWEB)

    Shores, D.A.; Selman, J.R.; Ong, E.T.

    1989-12-01

    This report describes the results of a three-year study of cathode degradation in molten carbonate fuel cells involving both experimental and theoretical work. A keystone of the study is the development of a mathematical model, which describes cathode degradation in terms of the fundamental processes of a fluxing mechanism, i.e., dissolution, transport and precipitation. New fundamental data have been obtained on the solubility of NiO, especially on the effect of water vapor, and on the kinetics of NiO dissolution in (Li{sub 0.62}K{sub 0.38}){sub 2}CO{sub 3}, and these data have been incorporated in the model. Laboratory cell testing in 3 cm{sup 2} cells has been carried out to obtain experimental data on degradation rates for direct comparison with the calculated results from the model. These comparisons have helped to verify several aspects of the model. For example, the model predicts with fair accuracy the location of the Ni deposit in the tile and the deposition rate. It is also fair to point out that the model is a relatively simple representation of complex processes, and it does not answer all questions about cathode degradation. Further work is needed. Because of its fundamental basis, the model can readily be upgraded and extended when further experimental data become available. The solubility studies, modeling efforts and cell testing have interacted iteratively to optimize progress. 94 figs., 24 tabs.

  6. RF MEMS

    Indian Academy of Sciences (India)

    of the switch were measured to be −0.43 dB, −25 dB and −21 dB, respectively ... The two ends of the CPW lines are RF ports of the switch. ... (b) Top view of the actuator showing segments comprising one of the four crableg beams. The short segments l1 and l4 are attached to the actuator and the rigid anchor, respectively.

  7. Rethinking Gun Violence

    OpenAIRE

    Greenberg, Mark; Litman, Harry

    2010-01-01

    This working paper develops the argument of "Gun Violence and Gun Control" (also posted on SSRN), a short piece commissioned by the London Review of Books. We decided not to publish either paper, in part because we felt there were empirical issues that we were not in a position to assess. We welcome comments on either paper. In this Article, we propose a new way of approaching the problem of gun violence, synthesizing features of a number of successful initiatives. We begin, in Pa...

  8. CNG7 Consolidated Nail Gun

    OpenAIRE

    DeSantis, Christopher Daniel

    2015-01-01

    The purpose of my study is to create a compact, portable nail gun. The nail gun is to be used in tight spaces where hammers, pneumatic nail guns, and portable nail guns will not fit. The intended market is for homeowners renovating their houses. The short length and lightweight, compact frame make the CNG7 ideal for this market. The CNG7 is designed with minimum material waste and fewer parts than other nail guns. MARCH

  9. Serbian society and gun culture

    OpenAIRE

    Cvetković Vladimir

    2006-01-01

    This paper questions whether one characteristic of Serbian society is a gun culture. The first part of the paper deals with some theoretical concerns and closer explanation of what is understood by the term gun culture. Few different approaches to the issue are analyzed. The concept used has three main components of the gun culture: system of positive beliefs; social symbols embodied by the gun; agent "bearers" of gun culture. The second part of the paper presents results from Small Arms and ...

  10. Analysis and experimental design of micro-pulse gun

    CERN Document Server

    Yang Xing Fan; LiuXiSan; LuHePing; Xu Zhou; Zhang Zhi Fu

    2002-01-01

    Micro-pulse gun (MPG) is a novel microwave electron gun. It is a kind of high brightness electron source. The concept of MPG has been studied in detail. The multipacting theory and self-bunching progress of the electron beam are discussed. The natural 'bunching', or resonant phase selection of the particles gives rise to high current density (kA/cm sup 2 ). The saturated beam pulse width is found to be typically 5% of the RF period. The cavity parameters such as the accelerating gap width and electric field are determined based on the theory. The cavity design and the dynamical simulation result are also presented

  11. Gun Dynamics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Gun Dynamics Laboratory is a research multi-task facility, which includes two firing bays, a high bay area and a second floor laboratory space. The high bay area...

  12. High Velocity Gas Gun

    Science.gov (United States)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  13. Teen Suicide and Guns

    Science.gov (United States)

    ... Health Issues Listen Text Size Email Print Share Teen Suicide and Guns Page Content Article Body Protect ... thinking of a passing problem, not the outcome! Teen Suicide—A Big Problem Suicide is one of ...

  14. Gun control saves lives.

    Science.gov (United States)

    Matzopoulos, Richard

    2016-05-19

    Reducing firearm mortality by means of stricter gun control is one of the most important short- to medium-term measures to address the burden of violence in South Africa, while longer-term interventions and policy measures take effect.

  15. Calculating effective gun policies

    OpenAIRE

    Wodarz, D; Komarova, NL

    2017-01-01

    Following recent shootings in the USA, a debate has erupted, one side favoring stricter gun control, the other promoting protection through more weapons. We provide a scientific foundation to inform this debate, based on mathematical, epidemiological models that quantify the dependence of firearm-related death rates of people on gun policies. We assume a shooter attacking a single individual or a crowd. Two strategies can minimize deaths in the model, depending on parameters...

  16. Gun Control Legislation

    Science.gov (United States)

    2010-08-27

    under the Constitution? Does gun control help reduce violent crime? Would household, street corner, and schoolyard disputes be less lethal if firearms...instructions, searching existing data sources, gathering and maintaining the data needed , and completing and reviewing the collection of information...household, street corner, and schoolyard disputes be less lethal if firearms were more difficult and expensive to acquire? Would more restrictive gun

  17. Alcoholism and gun control.

    Science.gov (United States)

    el-Guebaly, N; Lee, M

    1977-08-01

    The recurring dilemma of having to deal with an intoxicated person in possession of a gun uttering homicidal or suicidal threats along with the current debate on gun control prompted this controlled survey of the characteristics of individuals with problems arising from the joint abuse of alcohol and possession of a gun. A comparison of the data point to violence as being the most significant differentiating variable involved. This violent potential was reflected by the presence among the alcoholics involved of more past and present antisocial traits, a higher rating on the Nicol's scale of violence, more offences committed against the person and homicidal behaviour. The availability of a gun was a significant factor. No correlation was found between the severity of the drinking problem and the risk of dangerous handling of a gun. The need for more stringent gun controls is supported but their implications to the physician and especially the psychiatrist as a potential guarantor for a licence application ought to be further explored by the professional bodies involved.

  18. OPTIMIZATION OF OPERATION PARAMETERS OF 80-KEV ELECTRON GUN

    Directory of Open Access Journals (Sweden)

    JEONG DONG KIM

    2014-06-01

    As a first step, the electron generator of an 80-keV electron gun was manufactured. In order to produce the high beam power from electron linear accelerator, a proper beam current is required form the electron generator. In this study, the beam current was measured by evaluating the performance of the electron generator. The beam current was determined by five parameters: high voltage at the electron gun, cathode voltage, pulse width, pulse amplitude, and bias voltage at the grid. From the experimental results under optimal conditions, the high voltage was determined to be 80 kV, the pulse width was 500 ns, and the cathode voltage was from 4.2 V to 4.6 V. The beam current was measured as 1.9 A at maximum. These results satisfy the beam current required for the operation of an electron linear accelerator.

  19. A novel electron gun for inline MRI-linac configurations

    International Nuclear Information System (INIS)

    Constantin, Dragoş E.; Fahrig, Rebecca; Holloway, Lois; Keall, Paul J.

    2014-01-01

    Purpose: This work introduces a new electron gun geometry capable of robust functioning in the presence of a high strength external magnetic field for axisymmetric magnetic resonance imaging (MRI)-linac configurations. This allows an inline MRI-linac to operate without the need to isolate the linear accelerator (linac) using a magnetic shield. This MRI-linac integration approach not only leaves the magnet homogeneity unchanged but also provides the linac flexibility to move along the magnet axis of symmetry if the source to target distance needs to be adjusted. Methods: Simple electron gun geometry modifications of a Varian 600C electron gun are considered and solved in the presence of an external magnetic field in order to determine a set of design principles for the new geometry. Based on these results, a new gun geometry is proposed and optimized in the fringe field of a 0.5 T open bore MRI magnet (GE Signa SP). A computer model for the 6 MeV Varian 600C linac is used to determine the capture efficiency of the new electron gun-linac system in the presence of the fringe field of the same MRI scanner. The behavior of the new electron gun plus the linac system is also studied in the fringe fields of two other magnets, a 1.0 T prototype open bore magnet and a 1.5 T GE Conquest scanner. Results: Simple geometrical modifications of the original electron gun geometry do not provide feasible solutions. However, these tests show that a smaller transverse cathode diameter with a flat surface and a slightly larger anode diameter could alleviate the current loss due to beam interactions with the anode in the presence of magnetic fields. Based on these findings, an initial geometry resembling a parallel plate capacitor with a hole in the anode is proposed. The optimization procedure finds a cathode-anode distance of 5 mm, a focusing electrode angle of 5°, and an anode drift tube length of 17.1 mm. Also, the linac can be displaced with ±15 cm along the axis of the 0.5 T

  20. Modelling and simulation of beam formation in electron guns

    International Nuclear Information System (INIS)

    Sabchevski, S.; Barbarich, I.

    1996-01-01

    This paper describes a new PC version of the software package GUN-EBT for computer simulation of beam formation in rotationally symmetric electron guns with thermionic cathodes. It is based on a self-consistent physical model which takes into account the beam space charge and the initial velocity effects. The theoretical framework used for both the formulation of the model and for the interpretation of the results of numerical experiments is the formalism of the charged particle dynamics in phase space. This enables not only a trajectory analysis (ray tracing) but also a phase-space analysis of beams to be performed. The package can be used as an effective tool for computer aided design and optimization of electron guns in various electron-optical systems. The operation of the package is illustrated with a typical example. (orig.)

  1. Modelling and simulation of beam formation in electron guns

    Energy Technology Data Exchange (ETDEWEB)

    Sabchevski, S. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. po Elektronika; Mladenov, G. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. po Elektronika; Titov, A. [St. Petersburg State Electrotechnical University, St. Petersburg (Russian Federation); Barbarich, I. [St. Petersburg State Electrotechnical University, St. Petersburg (Russian Federation)

    1996-11-01

    This paper describes a new PC version of the software package GUN-EBT for computer simulation of beam formation in rotationally symmetric electron guns with thermionic cathodes. It is based on a self-consistent physical model which takes into account the beam space charge and the initial velocity effects. The theoretical framework used for both the formulation of the model and for the interpretation of the results of numerical experiments is the formalism of the charged particle dynamics in phase space. This enables not only a trajectory analysis (ray tracing) but also a phase-space analysis of beams to be performed. The package can be used as an effective tool for computer aided design and optimization of electron guns in various electron-optical systems. The operation of the package is illustrated with a typical example. (orig.).

  2. A design study of non-adiabatic electron guns

    International Nuclear Information System (INIS)

    Barroso, J.J.; Stellati, C.

    1994-01-01

    The design of a non-adiabatic gun capable of producing a 10 A, 50 KeV high-quality laminar electron beam is reported. In contrast to the magnetron injection gun with a conical cathode, where the beam is generated initially with a transverse velocity component, in the non-adiabatic gun electrons are extracted in a direction parallel to the axial guide magnetic field. The beam electrons acquire cyclotron motion as result of non-adiabatic processes in a strong non uniform electric field across the modulation anode. Such an extraction method gives rise to favourable features that are explored throughout the work. An extensive numerical simulation study has also been done to minimize velocity and energy spreads. (author). 3 refs, 5 figs, 1 tab

  3. Supply system with microprocessor control for electron gun

    International Nuclear Information System (INIS)

    Duplin, N.I.; Sergeev, N.N.

    1988-01-01

    Precision supply system for electron gun used in Auger-spectrometer is described. The supply system consists of control and high-voltage parts, made as separate units. Supply high-voltage unit includes system supply module, filament module to supply electron gun cathode and 6 high-volt modules to supply accelerating, modulating and three focusing electrodes of the gun. High-voltage modules have the following characteristics: U-(100-1000)V output voltage, 5x10 -5 U stability, 10 -5 xU pulsation amplitude, J-(0-5)A filament current change range at 10 -4 xJ stability. Control unit including microprocessor, timer and storage devices forms control voltage for all modules and regulates voltage and current of filament at electrodes

  4. Electron gun for high-performance color display tubes

    Science.gov (United States)

    Wang, Fangqin; Dong, Zhanfeng

    1998-08-01

    In order to design a high-performance electron gun, a new design concept was adapted to reduce the spherical aberration and coma of the electron optical system. In the electron gun we used a new asymmetric beam-forming region (BFR) and asymmetric main lens. This gun has been used for 40 cm 0.28 mm-pitch full square color display tubes. At cathode current of 0.2 microampere, the spot size on the screen center was measured 0.65 mm (10% of the maximum current distribution), and at the cathode current of 0.2 - 0.5 microampere, the focus voltage difference (focus trial characteristic) is less than 150 V. When the horizontal- scanning frequency reached 57 kHz, the tubes using the electron gun can display 1024 X 768 dots, and the corner- center focus performance is good. So it can meet the requirements of 40 cm 0.28 mm CDT of the market. In this design we used computer simulation software called Electron Beam Simulation to simulate the BFR and the main lens, through it we can adjust the lens structure, predict the performance and make it better. A good coincidence is obtained between the calculations and experiment results.

  5. Diagnostics Beamline for the SRF Gun Project

    CERN Document Server

    Kamps, T; Goldammer, K; Krämer, Dietrich; Kuske, P; Kuszynski, J; Lipka, D; Marhauser, F; Quast, T; Richter, R

    2005-01-01

    A superconducting rf photo electron injector (SRF gun) is currently under construction by a collaboration between BESSY, DESY, FZR and MBI. The project aims at the design and setup of an CW SRF gun including a diagnostics beamline for the ELBE FEL and to address R&D issues on low emittance injectors for future light sources such as the BESSY FEL. Of critical importance for the injector performance is the control of the electron beam parameters. For this reason a compact diagnostics beamline is under development serving a multitude of operation settings ranging from low-charge (77pC), low-emittance (1 pi mm mrad) mode to high-charge (2.5nC) operation of the gun. For these operation modes beam dynamics simulations are resulting in boundary conditions for the beam instrumentation. Proven and mature technology is projected wherever possible, for example for current and beam position monitoring. The layout of the beam profile and emittance measurement systems is described. For the bunch length, which varies be...

  6. Beam energy spread in FERMI(at)elettra gun and linac induced by intrabeam scattering

    International Nuclear Information System (INIS)

    Zholents, Alexander A; Zholents, Alexander A; Zolotorev, Max S.; Penco, Giuseppe

    2008-01-01

    Intrabeam scattering (IBS) of electrons in the pre-cathode area in the electron guns know in the literature as Boersh effect is responsible for a growth of the electron beam energy spread there. Albeit most visible within the electron gun where the electron beam density is large and the energy spread is small, the IBS acts all along the entire electron beam pass through the Linac. In this report we calculate the energy spread induced by IBS in the FERMI(at)elettra electron gun

  7. Electron-optical system of 200 kV gun for the VEPP-5 preinjector

    International Nuclear Information System (INIS)

    Akimov, V.E.; Kazarezov, I.V.; Tiunov, M.A.

    2004-01-01

    The electron gun with a new electron-optical system to match project parameters of the VEPP-5 preinjector is described. The gun produces the current with 10 A amplitude, pulse duration 2...3 ns at half-height and electron energy 200 keV. The gun has a dispenser cathode 20 mm in diameter and 100 mm spherical radius. The current control is performed by means of molybdenum equipotential grid with the cell size 0.4 centre dot 0.4 mm and optical transparency of about 0.68. The experimental results obtained are in good agreement with project parameters

  8. Emittance investigation of RF photo-injector

    CERN Document Server

    Yang Mao Rong; Li Zheng; Li Ming; Xu Zhou

    2002-01-01

    A high-power laser beam illuminates a photocathode surface placed on an end wall of an RF cavity. The emitted electrons are accelerated immediately to a relativistic energy by the strong RF find in the cavity. But space charge effect induces beam emittance growth especially near the cathode where the electrons are still nonrelativistic. The author analyzes the factors which lead the transverse emittance growth and method how to resolve this problem. After introducing solenoidal focusing near the photocathode, the beam emittance growth is suppressed dramatically. The beam emittance is given also after compensation and simulation results. The measurements show these results are coincident

  9. Thermionic gun control system for the CEBAF [Continuous Electron Beam Accelerator Facility] injector

    International Nuclear Information System (INIS)

    Pico, R.; Diamond, B.; Fugitt, J.; Bork, R.

    1989-01-01

    The injector for the CEBAF accelerator must produce a high-quality electron beam to meet the overall accelerator specifications. A Hermosa electron gun with a 2 mm-diameter cathode and a control aperture has been chosen as the electron source. This must be controlled over a wide range of operating conditions to meet the beam specifications and to provide flexibility for accelerator commissioning. The gun is controlled using Computer Automated Measurement and Control (CAMAC IEEE-583) technology. The system employs the CAMAC-based control architecture developed at CEBAF. The control system has been tested, and early operating data on the electron gun and the injector beam transport system has been obtained. This system also allows gun parameters to be stored at the operator location, without paralyzing operation. This paper describes the use of this computer system in the control of the CEBAF electron gun. 2 refs., 6 figs., 1 tab

  10. An economic model of gun control

    OpenAIRE

    O' Sullivan, Arthur

    1998-01-01

    Guns stolen from law-abiding households provide the principal source of guns for criminals. The lethality of crime instruments increases with the availability of guns, so the gun market is subject to externalities that generate excessive ownership and inadequate spending on protective measures to deter gun theft. One motive for gun ownership is self defense, and the gun market is subject to coordination failure: the more guns purchased lawfully, the more will be stolen by crimi...

  11. Electromagnetic Guns versus Conventional Guns - a performance comparison

    NARCIS (Netherlands)

    Reus, N.M. de; Weijden, J. van der

    1993-01-01

    Performance improvement is one of the key issues of Electromagnetic gun systems compared to conventional gun systems. Due to higher muzzle velocities, the gun's fire control computer will be able to predict the target's future position more accurately because prediction time will be smaller. In this

  12. Fueling by coaxial plasma guns

    International Nuclear Information System (INIS)

    Marshall, J.

    1978-01-01

    The operating principles of pulsed coaxial guns are reviewed. Some problems involved with the injection of plasma beams from these guns into containment fields are described. The injection during reactor operating conditions is then discussed

  13. Where the guns come from: the gun industry and gun commerce.

    Science.gov (United States)

    Wintemute, Garen J

    2002-01-01

    Under federal law, it is illegal for youth under age 18 to purchase rifles or shotguns, and for those under age 21 to purchase handguns. However, fatality and injury statistics clearly show that guns are finding their way into young people's hands. Many of these youth obtain guns through illegal gun markets. This article focuses on how guns in the United States are manufactured, marketed, and sold. The article shows how the legal and illegal gun markets are intimately connected and make guns easily accessible to youth. Although the domestic gun manufacturing industry is relatively small and has experienced declining sales in recent years, it has significant political clout and a large market for its products, and has engaged in aggressive marketing to youth. Lax oversight of licensed firearms dealers, combined with little or no regulation of private sales between gun owners, mean that guns can quickly moved from the legal gun market into the illegal market, where they can be acquired by young people. Certain guns, especially inexpensive, poorly made small handguns, are particularly attractive to criminals and youth. The author observes that several policy innovations--including increased regulation of licensed firearms dealers, intensified screening of prospective buyers, regulation of private sales, gun licensing and registration, and bans on some types of weapons--hold promise for decreasing the flow of guns into the hands of youth.

  14. CAPE TOWN'S TIME-GUNS

    African Journals Online (AJOL)

    Although a great many articles have been writ- ten on the subject of Cape Town's noon gun (the. official terminology is 'time-gun') most of the writ- ers have not had access to the Lion Battery Fort. Record Book and the existance of more than one. Cape Town time-gun has only recently been re- corded. By 1807 a noon gun ...

  15. Optimizing SRF Gun Cavity Profiles in a Genetic Algorithm Framework

    International Nuclear Information System (INIS)

    Hofler, Alicia; Evtushenko, Pavel; Marhauser, Frank

    2009-01-01

    Automation of DC photoinjector designs using a genetic algorithm (GA) based optimization is an accepted practice in accelerator physics. Allowing the gun cavity field profile shape to be varied can extend the utility of this optimization methodology to superconducting and normal conducting radio frequency (SRF/RF) gun based injectors. Finding optimal field and cavity geometry configurations can provide guidance for cavity design choices and verify existing designs. We have considered two approaches for varying the electric field profile. The first is to determine the optimal field profile shape that should be used independent of the cavity geometry, and the other is to vary the geometry of the gun cavity structure to produce an optimal field profile. The first method can provide a theoretical optimal and can illuminate where possible gains can be made in field shaping. The second method can produce more realistically achievable designs that can be compared to existing designs. In this paper, we discuss the design and implementation for these two methods for generating field profiles for SRF/RF guns in a GA based injector optimization scheme and provide preliminary results.

  16. Children, Youth, and Gun Violence.

    Science.gov (United States)

    Behrman, Richard E., Ed.

    2002-01-01

    This collection of articles summarizes knowledge and research about how gun violence affects children and youth and discusses which policies hold promise for reducing youth gun violence. The papers are: (1) "Statement of Purpose" (Richard E. Behrman); "Children, Youth, and Gun Violence: Analysis and Recommendations" (Kathleen…

  17. Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A [HZDR, Dresden, Germany; Freitag, M [HZDR, Dresden, Germany; Murcek, Petr [HZDR, Dresden, Germany; Teichert, Jochen [HZDR, Dresden, Germany; Vennekate, H [HZDR, Dresden, Germany; Xiang, R [HZDR, Dresden, Germany; Ciovati, Gianluigi [JLAB; Kneisel, Peter K. [JLAB; Turlington, Larry D, [JLAB

    2014-12-01

    As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation, it turned out that the specified performance has not been achieved. However, to demonstrate the full potential of this new type of electron source, a second and slightly modified SRF gun II was built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of the new gun, which includes in particular the characterization of the most important RF properties as well as their comparison with previous vertical test results.

  18. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  19. Nanotube cathodes

    International Nuclear Information System (INIS)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-01-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  20. Data transmission optical link for RF-GUN project

    Science.gov (United States)

    Olowski, Krzysztof; Zielinski, Jerzy; Jalmuzna, Wojciech; Pozniak, Krzysztof; Romaniuk, Ryszard

    2005-09-01

    Today, the fast optical data transmission is one of the fundamentals of modern distributed control systems. The fibers are widely use as multi-gigabit data stream medium. For a short range transmission, the multimode fibers are in common use. The data rate for this kind of transmission exceeds 10 Gbps for 10 Gigabit Ethernet and 10G Fibre Channel protocols. The Field Programmable Gate Arrays are one of the opportunities of managing the optical transmission. This article is concerning a synchronous optical transmission system via a multimode fiber. The transmission is controlled by the FPGA of two manufacturers: Xilinx and Altera. This paper contains the newest technology overview and market device parameters. It also describes a board for the optical transmission, technical details of the transmission and optical transmission results.

  1. Researches on new photocathode for RF electron gun

    CERN Document Server

    ZhaoKui; Tang Yu Xing; Zhao Kun; Wang Li; Zhang Bao Cheng; Chen J

    2000-01-01

    Semiconductor photocathode and metal photocathode have different properties. To consider the properties of both, we studied a new type of photocathode - ion implanted photocathode. Cesium ions are implanted into a metal substrate. A photocathode preparation chamber is set up to make this photocathode. A cesium ion source is attached to the common photocathode preparation chamber. In the past two years, we finished making this photocathode and did research on its properties. A series of experiments have been done with different metal substrates, implanting dosages and implanting energies, in order to get a kind of photocathode material with high quantum efficiency and good stability. An increase of quantum efficiency after implantation has been observed. A more interesting result is that the emission spectrum becomes broader.

  2. Guns, Germs and Steel

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 1. Guns, Germs and Steel - A Short History of Everybody for the Last 13,000 years. Suri Venkatachalam. Book Review Volume 6 ... Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/01/0084-0088 ...

  3. Gun Internal Ballistics.

    Science.gov (United States)

    An approximate method of analysis is formulated for gun internal ballistics. The method is incorporated in a digital computer program which is...described. The validity of the method of analysis and computational procedure is substantiated by comparison of theoretical results with experimental

  4. Gun control saves lives

    African Journals Online (AJOL)

    implementation of laws encompassing multiple firearm restrictions in certain countries. The authors cited, alongside examples from the. USA, Canada, Australia, New Zealand and Brazil, SA's FCA, which banned certain types of firearm, required training tests for licences, additional licences for each gun owned, increased ...

  5. Gun Dealers, USA.

    Science.gov (United States)

    Duker, Laurie; And Others

    In the United States, more than 11,500 adolescents' and young adults' lives are taken each year by firearms. Although Federal law prohibits minors from purchasing handguns, they typically get them by asking someone of legal age (18 years or older) to purchase them from one of the 256,771 Federally licensed gun dealers. This pamphlet answers…

  6. Radar gun hazards

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-20

    Radar guns - hand-held units used by the law to nail speeders - have been in use since the early '60s. Now they've been accused of causing cancer. Police officers in several states have so far filed eight suits against the manufacturer, claiming that they have contracted rare forms of cancer, such as of the eyelid and the testicle, from frequent proximity to the devices. Spurred by concerns expressed by police groups, researchers at the Rochester Institute of Technology are conducting what they believe to be the first research of its kind in the nation. Last month psychologist John Violanti, an expert in policy psychology and health, sent out a one-page survey to 6,000 active and retired police officers in New York State, asking them about their health and their use of radar guns. Violanti says melanoma, leukemia, and lymph node cancer may be linked to these as well as other electromagnetic devices. The Food and Drug Administration earlier this year issued a warning about radar guns, telling users not to operate them closer than 6 inches from the body. But this may not be a sufficient safeguard since the instruments can give off crisscrossing wave emissions within a police vehicle. The survey will be used to help determine if it would be safer to mount the guns, which are currently either hand-held or mounted on dashboards, outside troopers' cars.

  7. Guns, Germs and Steel

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 1. Guns, Germs and Steel - A Short History of Everybody for the Last 13,000 years. Suri Venkatachalam. Book Review Volume 6 Issue 1 January 2001 pp 84-88. Fulltext. Click here to view fulltext PDF. Permanent link:

  8. Direct RF modulation transmitter

    NARCIS (Netherlands)

    Fukuda, Shuichi; Nauta, Bram

    2013-01-01

    PROBLEM TO BE SOLVED: To provide a direct RF modulation transmitter capable of saving more power consumption. SOLUTION: The direct RF modulation transmitter comprises: a passive mixer circuit 100 which inputs digital baseband data D of 1 bit, inverted data DN, a first RF signal, and a second RF

  9. Generation of high-density O2 supermagnetron plasma over lower cathode by radio frequency power supply to upper cathode

    Science.gov (United States)

    Kinoshita, Haruhisa

    1994-02-01

    The density of supermagnetron plasma generated over a lower cathode, i.e., the wafer stage, was examined qualitatively by optical emission spectroscopy and compared to the results of Ar plasma measured by a similar method. Optical emission intensities (OEIs) of O (or Ar) atoms and O (or Ar) ions over the lower cathode were increased with each rf power. By increasing the upper cathode rf power (UPRF), a remarkable increase of OEI was observed at approximately 180° of the phase difference of two synchronous rf powers supplied to two cathodes, but there was a slight increase observed at approximately 0°. A lot of negative self-bias voltage was observed at about 180°, but there was little positive voltage observed at approximately 0°. The etch rate of the photoresist was increased with UPRF at 150° without increasing the self-bias voltage of the lower cathode. Highly uniform etching of ±5% was obtained in a 5-in.-diam photoresist wafer etching using a stationary magnetic field. 0.4 μm photoresist lines were etched vertically by using an upper cathode covered by a carbon plate.

  10. Cathodic protection -- Rectifier 46

    Energy Technology Data Exchange (ETDEWEB)

    Lane, W.M. [Westinghouse Hanford Co., Richland, WA (United States)

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive waste.

  11. Cathodic protection -- Rectifier 47

    Energy Technology Data Exchange (ETDEWEB)

    Lane, W.M. [Westinghouse Hanford Co., Richland, WA (United States)

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste.

  12. Cathodic protection -- Rectifier 47

    International Nuclear Information System (INIS)

    Lane, W.M.

    1995-01-01

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste

  13. Development of an S-band high-power pillbox-type RF window

    International Nuclear Information System (INIS)

    Miura, A.; Matsumoto, H.

    1992-01-01

    We report on the development of RF windows used to handle a high transmission power up to 110 MW for the Japan Linear Collider. A detailed simulation on multipactoring has been carried out. The results were compared with cathode-luminescence on the surface of alumina RF windows experimentally observed with power transmission up to 200 MW. (Author) 10 refs., 9 figs

  14. RK-TBA prototype RF source

    International Nuclear Information System (INIS)

    Houck, T.; Anderson, D.; Giordano, G.

    1996-01-01

    A prototype rf power source based on the Relativistic Klystron Two-Beam Accelerator (RK-TBA) concept is being constructed at the Lawrence Berkeley National Laboratory to study physics, engineering, and costing issues. The prototype is described and compared to a full scale design appropriate for driving the Next Linear Collider (NLC). Specific details of the induction core tests and pulsed power system are presented. The 1-MeV, 1.2-kA induction gun currently under construction is also described in detail

  15. Design of e-gun for large KrF amplifiers

    International Nuclear Information System (INIS)

    Reilly, D.A.; Von Rosenberg, C.W.

    1985-01-01

    The design of very large single-aperture laser amplifier for an angular multiplexed laser fusion system requires advances in excimer laser e-gun technology beyond existing designs. Scaling considerations dictate the use of multiple e-guns to pump a single laser; in the present case the authors will discuss the scaling and design features of one of the ten e-guns being developed to pump the Los Alamos Polaris Power Amplifier Module. Multiple e-guns minimize the diode self-magnetic field, lowering the size of the imposed guide magnetic field, and reducing the diode impendance collapse. Multiple guns also result in lowered current rise times, reduce the development cost of the technology at the prototype stage, and, of course, limit the cost due to operation failures in the e-gun. The present design utilizes the expanding electron flow diode to provide uniform electron flow into the gas from a high-current density cold cathode (approx. =50 A/cm 2 ). Laminated iron and an imposed dipole field are utilized for B-field shaping. The applied B field lines trace from the anode, terminate on the cathode, and are then conducted through the shank to beyond the bushing. This feature not only provides for fully expanded electron flow from cathode to anode, but it also allows for self-magnetic field insulation of the shank and bushing, thus minimizing voltage standoff distances, inductance, and rise time. A single large aspect ratio racetrack-shaped bushing on each e-gun is provided with robust grading to limit field concentration at the ends

  16. Mole gun injury.

    Science.gov (United States)

    Pistré, V; Rezzouk, J

    2013-09-01

    A mole gun is a weapon, which is used to trap and kill moles. This report provides an overview of the state of knowledge of mole gun injuries, comparable to blast injuries caused by fireworks, explosive or gunshot. Over a 2-year period, the authors reported their experience with ten hand injuries caused by mole gun. Radial side of the hand was often concerned, particularly the thumb. The authors explain their choices in the management of such lesions. Surgery was performed primarily and a large debridement currently seemed to offer the best outcome for the patient. Blast, crush, burns and lacerations may explain the higher rate of amputation to the digits. A long period of physiotherapy, specifically of the hand, was needed before the patient could return to work. This ballistic hand trauma encountered by surgeons requires knowledge and understanding of these injuries. It should be in accordance with firearms law because of severe injuries encountered and possible lethal wounds. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  17. Recycler barrier RF buckets

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; /Fermilab

    2011-03-01

    The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.

  18. High-Current Cold Cathode Employing Diamond and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

    2014-10-22

    The essence of this project was for diamond films to be deposited on cold cathodes to improve their emission properties. Films with varying morphology, composition, and size of the crystals were deposited and the emission properties of the cathodes that utilize such films were studied. The prototype cathodes fabricated by the methods developed during Phase I were tested and evaluated in an actual high-power RF device during Phase II. These high-power tests used the novel active RF pulse compression system and the X-band magnicon test facility at US Naval Research Laboratory. In earlier tests, plasma switches were employed, while tests under this project utilized electron-beam switching. The intense electron beams required in the switches were supplied from cold cathodes embodying diamond films with varying morphology, including uncoated molybdenum cathodes in the preliminary tests. Tests with uncoated molybdenum cathodes produced compressed X-band RF pulses with a peak power of 91 MW, and a maximum power gain of 16.5:1. Tests were also carried out with switches employing diamond coated cathodes. The pulse compressor was based on use of switches employing electron beam triggering to effect mode conversion. In experimental tests, the compressor produced 165 MW in a ~ 20 ns pulse at ~18× power gain and ~ 140 MW at ~ 16× power gain in a 16 ns pulse with a ~ 7 ns flat-top. In these tests, molybdenum blade cathodes with thin diamond coatings demonstrated good reproducible emission uniformity with a 100 kV, 100 ns high voltage pulse. The new compressor does not have the limitations of earlier types of active pulse compressors and can operate at significantly higher electric fields without breakdown.

  19. JAERI 200 kV Electron Gun with an NEA-GaAs Photocathode

    CERN Document Server

    Nishitani, Tomohiro; Kikuzawa, Nobuhiro; John Minehara, Eisuke; Nagai, Ryoji; Nishimori, Nobuyuki; Sawamura, Masaru; Yamauchi, T

    2004-01-01

    The GaAs photocathode with negative electron affinity surface (NEA-GaAs) has been expected to be low emittance (<0.5 πmm・mrad) electron beam source. In order to generate low emittance electron beam required from ERL-FEL, we have started the developmental program of a 200keV electron gun with the NEA-GaAs photocathode for the first time in JAERI. An NEA surface has the problem that lifetime is limited by gun vacuum condition and by ion back bombardment between anode- and cathode-electrode. In order to long an NEA surface lifetime, the JAERI 200keV electron gun system consists of a 200kV DC-gun chamber on extreme high vacuum condition and an NEA activation chamber with load-lock system.

  20. Power-supply system for high-voltage electron guns with grid control

    International Nuclear Information System (INIS)

    Grigorev, Y.V.

    1985-01-01

    A power-supply system for electron guns with grid control is described which consists of a source of accelerating voltage between 20 and 180 kV with a current of 100 mA and a control circuit for an electron gun that contains a pulse generator having an output voltage of up to 5 kV for pulse durations of 2, 10, 50 and 90 microseconds. The output pulses of the generator are synchronized with a certain phase of the cathode heater current of the gun, and they can be repeated at a frequency between 100 and 0.4 Hz. The system is reliable and resistant to the overloads associated with breakdowns in the gun

  1. Wisconsin SRF Electron Gun Commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Bisognano, Joseph J. [University of Wisconsin-Madison; Bissen, M. [University of Wisconsin-Madison; Bosch, R. [University of Wisconsin-Madison; Efremov, M. [University of Wisconsin-Madison; Eisert, D. [University of Wisconsin-Madison; Fisher, M. [University of Wisconsin-Madison; Green, M. [University of Wisconsin-Madison; Jacobs, K. [University of Wisconsin-Madison; Keil, R. [University of Wisconsin-Madison; Kleman, K. [University of Wisconsin-Madison; Rogers, G. [University of Wisconsin-Madison; Severson, M. [University of Wisconsin-Madison; Yavuz, D. D. [University of Wisconsin-Madison; Legg, Robert A. [JLAB; Bachimanchi, Ramakrishna [JLAB; Hovater, J. Curtis [JLAB; Plawski, Tomasz [JLAB; Powers, Thomas J. [JLAB

    2013-12-01

    The University of Wisconsin has completed fabrication and commissioning of a low frequency (199.6 MHz) superconducting electron gun based on a quarter wave resonator (QWR) cavity. Its concept was optimized to be the source for a CW free electron laser facility. The gun design includes active tuning and a high temperature superconducting solenoid. We will report on the status of the Wisconsin SRF electron gun program, including commissioning experience and first beam measurements.

  2. RF multipole implementation

    CERN Document Server

    Latina, A

    2012-01-01

    The electromagnetic radio-frequency (RF) field of accelerating structures and crab-cavities can exhibit transverse field components due to asymmetries in the azimuthal direction of the element geometry. Tracking simulations must be performed to evaluate the impact of such transverse RF deflections on the beam dynamics. In an ultra-relativistic regime where the Panofsky-Wenzel theorem is applicable, these RF deflections can be modeled via a multipolar expansion of the generating RF field similarly to what is done with static magnetic elements. The element implementing such RF multipolar fields has been called RF multipole. In this note we present an analytical formulation of a thin RF multipole Hamiltonian, and we explicitly calculate the RF kick and the elements of its first- and second- order transfer matrices. Also, we present the implementation of the corresponding code in MAD-X, plus some tests of tracking, simplecticity, consistency, and reflected maps that we successfully applied to verify the correctne...

  3. Design, operation, and test results of 350 MHz LEDA RF system

    International Nuclear Information System (INIS)

    Rees, D.; Bradley, J. III; Cummings, K.; Regan, A.; Rohlev, T.; Roybal, W.; Wang, Y.M.

    1998-01-01

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. The APT accelerator requires over 244 RF systems each with a continuous wave output power of 1 MW. The reliability and availability of these RF systems is critical to the successful operation of APT plant and prototypes of these systems are being developed and demonstrated on LEDA. The first completed LEDA RF systems are three, 1.2 MW, 350 MHz, continuous wave, klystrons driving a radio frequency quadrupole (RFQ). This paper presents the design and test results for these RF systems including the klystrons, cathode power supply, circulators, RF vacuum windows, and RF components. The three RF systems driving the RFQ use the accelerating structure as a power combiner and this places some unique requirements on the RF systems. These requirements and corresponding operational implications are discussed

  4. Understanding and Predicting Gun Barrel Erosion

    National Research Council Canada - National Science Library

    Johnston, Ian A

    2005-01-01

    The Australian Defence Force will soon have to contend with gun barrel erosion issues arising from the use of new low-vulnerability gun propellants, the acquisition of new ammunition and gun systems...

  5. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    Science.gov (United States)

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

  6. Thermal and mechanical study of a MIG-type electron gun for a 31 GHz, 100 k W gyrotron

    International Nuclear Information System (INIS)

    Patire Junior, H.; Barroso, J.J.

    1994-01-01

    A thermal and mechanical study of a MIG-type electron gun has been made to determine the temperature distribution in all the gun elements as a function of the input heater power. Appropriate materials were selected to minimize both the conduction and radiation thermal losses. The electron emitting surface operates at an average temperature of 1000 0 C with 374 W input power in the heating filament system. The purpose of the present study is to reduce the input heater power while keeping the required operating cathode temperature and to improve the gun design from a constructional point of view aiming at extending the capabilities of the electron gun. A thermal software has been used by considering the operation conditions taking into account external convection by forced air and thermal radiation transfer between the electrodes of the gun. (author). 5 refs, 4 figs, 1 tab

  7. Gun Concerns Personal for Duncan

    Science.gov (United States)

    McNeil, Michele

    2013-01-01

    As U.S. Secretary of Education Arne Duncan works with other Obama administration officials on policy responses to the shootings at a Connecticut elementary school, he brings a personal and professional history that has acquainted him with the impact of gun violence. As schools chief in Chicago from 2001 to 2008, he was affected by the gun deaths…

  8. Gun violence trends in movies

    NARCIS (Netherlands)

    Bushman, B.J.; Jamieson, P.E.; Weitz, I.; Romer, D.

    2013-01-01

    BACKGROUND: Many scientific studies have shown that the mere presence of guns can increase aggression, an effect dubbed the "weapons effect." The current research examines a potential source of the weapons effect: guns depicted in top-selling films. METHODS: Trained coders identified the presence of

  9. Large-Grain Superconducting Gun Cavity Testing Program Phase One Closing Report

    Energy Technology Data Exchange (ETDEWEB)

    Hammons, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Bellavia, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Cullen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Dai, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Degen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hahn, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Masi, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); McIntyre, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schultheiss, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Seda, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Kellerman, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tallerico, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Todd, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tuozzolo, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Than, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2013-10-31

    This report details the experimental configuration and RF testing results for the first phase of a large-grained niobium electron gun cavity testing program being conducted in the Small Vertical Testing Facility in the Collider-Accelerator Department. This testing is meant to explore multi-pacting in the cavity and shed light on the behavior of a counterpart cavity of identical geometry installed in the Energy Recovery LINAC being constructed in the Collider-Accelerator Department at Brookhaven National Laboratory. This test found that the Q of the large-grained cavity at 4 K reached ~6.5 × 108 and at 2 K reached a value of ~6 × 109. Both of these values are about a factor of 10 lower than would be expected for this type of cavity given the calculated surface resistance and the estimated geometry factor for this half-cell cavity. In addition, the cavity reached a peak voltage of 0.6 MV before there was sig-nificant decline in the Q value and a substantial increase in field emission. This relatively low volt-age, coupled with the low Q and considerable field emission suggest contamination of the cavity interior, possibly during experimental assembly. The results may also suggest that additional chemical etching of the interior surface of the cavity may be beneficial. Throughout the course of testing, various challenges arose including slow helium transfer to the cryostat and cable difficulties. These difficulties and others were eventually resolved, and the re-port discusses the operating experience of the experiment thus far and the plans for future work aimed at exploring the nature of multipacting with a copper cathode inserted into the cavity.

  10. Preventing gun injuries in children.

    Science.gov (United States)

    Crossen, Eric J; Lewis, Brenna; Hoffman, Benjamin D

    2015-02-01

    Firearms are involved in the injury and death of a large number of children each year from both intentional and unintentional causes. Gun ownership in homes with children is common, and pediatricians should incorporate evidence-based means to discuss firearms and protect children from gun-related injuries and violence. Safe storage of guns, including unloaded guns locked and stored separately from ammunition, can decrease risks to children, and effective tools are available that pediatricians can use in clinical settings to help decrease children's access to firearms. Furthermore, several community-based interventions led by pediatricians have effectively reduced firearm-related injury risks to children. Educational programs that focus on children's behavior around guns have not proven effective. © American Academy of Pediatrics, 2015. All rights reserved.

  11. Electric arc welding gun

    Science.gov (United States)

    Luttrell, Edward; Turner, Paul W.

    1978-01-01

    This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

  12. Guns and sleep

    Directory of Open Access Journals (Sweden)

    Quan SF

    2015-08-01

    Full Text Available No abstract available. Article truncated at 150 words. Gun deaths are a problem in America. Irrespective of one’s position on gun control, the statistics do not lie. According to the Centers for Disease Control and Prevention (CDC, there were 11,208 deaths caused by firearms in 2013 (1. The recent high profile cases in Cincinnati, OH, Lafayette, LA and Memphis, TN further highlight the issue. Obviously, each case of death by a firearm had its own set of underlying factors that contributed to the final fatal outcome, but one wonders whether sleep deprivation can be implicated in some of them. Sleep duration in adults over the past approximately 30 years has been declining in the United States (2. A variety of reasons can be cited as underlying causes such as greater use of artificial lighting, an expanding 24 hour non-stop society, promotion of a work ethic that values “burning the midnight oil”, and use of electronic devices before bedtime ...

  13. Comment on the mechanism of operation of the impregnated tungsten cathode

    Science.gov (United States)

    Forman, R.

    1979-01-01

    Recent life-test measurements, over 20,000-30,000 h, on impregnated tungsten cathodes in tubes employing an open-type electron-gun structure, show emission current degradation with time. This is in contrast to those recently published by Rittner on B-type cathodes, run in close-spaced diodes, taken some years ago. These more recent life-test results are consistent with the model suggested by Forman and disputed by Rittner that the barium coverage on an impregnated cathode is less than a monolayer for most of its life and decreases with time.

  14. Cathodic Protection Model Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Performs Navy design and engineering of ship and submarine impressed current cathodic protection (ICCP) systems for underwater hull corrosion control and...

  15. Gun Shows and Gun Violence: Fatally Flawed Study Yields Misleading Results

    Science.gov (United States)

    Hemenway, David; Webster, Daniel; Pierce, Glenn; Braga, Anthony A.

    2010-01-01

    A widely publicized but unpublished study of the relationship between gun shows and gun violence is being cited in debates about the regulation of gun shows and gun commerce. We believe the study is fatally flawed. A working paper entitled “The Effect of Gun Shows on Gun-Related Deaths: Evidence from California and Texas” outlined this study, which found no association between gun shows and gun-related deaths. We believe the study reflects a limited understanding of gun shows and gun markets and is not statistically powered to detect even an implausibly large effect of gun shows on gun violence. In addition, the research contains serious ascertainment and classification errors, produces results that are sensitive to minor specification changes in key variables and in some cases have no face validity, and is contradicted by 1 of its own authors’ prior research. The study should not be used as evidence in formulating gun policy. PMID:20724672

  16. Gun shows and gun violence: fatally flawed study yields misleading results.

    Science.gov (United States)

    Wintemute, Garen J; Hemenway, David; Webster, Daniel; Pierce, Glenn; Braga, Anthony A

    2010-10-01

    A widely publicized but unpublished study of the relationship between gun shows and gun violence is being cited in debates about the regulation of gun shows and gun commerce. We believe the study is fatally flawed. A working paper entitled "The Effect of Gun Shows on Gun-Related Deaths: Evidence from California and Texas" outlined this study, which found no association between gun shows and gun-related deaths. We believe the study reflects a limited understanding of gun shows and gun markets and is not statistically powered to detect even an implausibly large effect of gun shows on gun violence. In addition, the research contains serious ascertainment and classification errors, produces results that are sensitive to minor specification changes in key variables and in some cases have no face validity, and is contradicted by 1 of its own authors' prior research. The study should not be used as evidence in formulating gun policy.

  17. The Effects of Gun Ownership Rates and Gun Control Laws on Suicide Rates

    OpenAIRE

    Mark Gius

    2011-01-01

    The purpose of the present study is to determine the effects of gun control laws and gun ownership rates on state-level suicide rates. Using the most recent data on suicide rates, gun control measures, and gun ownership rates, the results of the present study suggest that states that require handgun permits have lower gun-related suicide rates, and states that have higher gun ownership rates have higher gun-related suicide rates. Regarding non-gun suicides, results suggest that stricter gun c...

  18. High Current Oxide Cathodes

    National Research Council Canada - National Science Library

    Luhmann, N

    2000-01-01

    .... The vacuum are plasma deposition gun developed at Lawrence Berkeley National Laboratory (LBNL) has been used to deposit oxides and nitrides with very precise control over deposition rate and composition.

  19. Gun violence trends in movies.

    Science.gov (United States)

    Bushman, Brad J; Jamieson, Patrick E; Weitz, Ilana; Romer, Daniel

    2013-12-01

    Many scientific studies have shown that the mere presence of guns can increase aggression, an effect dubbed the "weapons effect." The current research examines a potential source of the weapons effect: guns depicted in top-selling films. Trained coders identified the presence of violence in each 5-minute film segment for one-half of the top 30 films since 1950 and the presence of guns in violent segments since 1985, the first full year the PG-13 rating (age 13+) was used. PG-13-rated films are among the top-selling films and are especially attractive to youth. Results found that violence in films has more than doubled since 1950, and gun violence in PG-13-rated films has more than tripled since 1985. When the PG-13 rating was introduced, these films contained about as much gun violence as G (general audiences) and PG (parental guidance suggested for young children) films. Since 2009, PG-13-rated films have contained as much or more violence as R-rated films (age 17+) films. Even if youth do not use guns, these findings suggest that they are exposed to increasing gun violence in top-selling films. By including guns in violent scenes, film producers may be strengthening the weapons effect and providing youth with scripts for using guns. These findings are concerning because many scientific studies have shown that violent films can increase aggression. Violent films are also now easily accessible to youth (e.g., on the Internet and cable). This research suggests that the presence of weapons in films might amplify the effects of violent films on aggression.

  20. Rf Feedback free electron laser

    Science.gov (United States)

    Brau, Charles A.; Swenson, Donald A.; Boyd, Jr., Thomas J.

    1981-01-01

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

  1. Superconducting augmented rail gun (SARG)

    International Nuclear Information System (INIS)

    Homan, C.G.; Cummings, C.E.; Fowler, C.M.

    1986-01-01

    Superconducting augmentation consists of a superconducting coil operating in the persistent mode closely coupled magnetically with a normally conducting rail gun. A theoretical investigation of the effect of this system on a rail gun has shown that two benefits occur. Projectile velocities and launch efficiencies increase significantly depending on the magnetic coupling between the rail and augmentation circuits. Previous work evaluated an idealized system by neglecting energy dissipation effects. In this paper, the authors extend the analysis to include the neglected terms and show improved actual launch efficiencies for the SARG configuration. In this paper, the authors discuss details of projectile design in depth and present preliminary results of rail gun performance

  2. Gun barrel erosion - Comparison of conventional and LOVA gun propellants

    NARCIS (Netherlands)

    Hordijk, A.C.; Leurs, O.

    2006-01-01

    The research department Energetic Materials within TNO Defence, Security and Safety is involved in the development and (safety and insensitive munitions) testing of conventional (nitro cellulose based) and thermoplastic elastomer (TPE) based gun propellants. Recently our testing capabilities have

  3. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  4. RF power transport

    CERN Document Server

    Choroba, S

    2011-01-01

    This paper deals with the techniques of transport of high-power RF from an RF power source to the cavities of an accelerator. Since the theory of electromagnetic waves in waveguides and of waveguide components is very well explained in a number of excellent text books it will limit itself to special waveguide distributions and to some special problems which sometimes occur in RF power transportation systems.

  5. RF feedback for KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Ezura, Eizi; Yoshimoto, Shin-ichi; Akai, Kazunori [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    This paper describes the present status of the RF feedback development for the KEK B-Factory (KEKB). A preliminary experiment concerning the RF feedback using a parallel comb-filter was performed through a choke-mode cavity and a klystron. The RF feedback has been tested using the beam of the TRISTAN Main Ring, and has proved to be effective in damping the beam instability. (author)

  6. Effect of charge exchange on ion guns and an application to inertial- electrostatic confinement devices

    International Nuclear Information System (INIS)

    Baxter, D.C.; Stuart, G.W.

    1982-01-01

    In 1967, R. L. Hirsch [J. Appl. Phys. 38, 4522 (1967)] reported neutron production rates of 10 10 neutrons per second from an electrostatic inertial confinement device. The device consisted of six ion guns injecting deuterium or a mixture of deuterium and tritium ions into an evacuated cathode chamber at 30--150 keV. No previous theoretical model for this experiment has adequately explained the observed neutron fluxes. A new model that includes the effects of charge exchange and ionization in the ion guns is analyzed. This model predicts three main features of the observed neutron flux: Neutron output proportional to gun current, neutron production localized at the center of the evacuated chamber, and neutron production decreasing with increasing neutral background gas density. Previous analysis modelled the ion guns as being monoenergetic. In this study, the ion gun output is modelled as a mixture of ions and fast neutrals with energies ranging from zero to the maximum gun energy. Using this theoretical model, a survey of the possible operating parameters indicates that the device was probably operated at or near the most efficient combined values of voltage and background pressure. Applications of the theory to other devices are discussed

  7. Temporal association between federal gun laws and the diversion of guns to criminals in Milwaukee.

    Science.gov (United States)

    Webster, Daniel W; Vernick, Jon S; Bulzacchelli, Maria T; Vittes, Katherine A

    2012-02-01

    The practices of licensed gun dealers can threaten the safety of urban residents by facilitating the diversion of guns to criminals. In 2003, changes to federal law shielded gun dealers from the release of gun trace data and provided other protections to gun dealers. The 14-month period during which the dealer did not sell junk guns was associated with a 68% reduction in the diversion of guns to criminals within a year of sale by the dealer and a 43% increase in guns diverted to criminals following sales by other dealers. The laws were associated with a 203% increase in the number of guns diverted to criminals within a year of sale by the gun store, which was the focus of this study. Policies which affect gun dealer accountability appeared to influence the diversion of guns to criminals.

  8. Reverse Ballistic Air Gun Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This custom-designed facility houses a suite of three air guns capable of generating accelerations up to 100,000 Gs and velocities up to 2,000 ft/s. In addition to a...

  9. Design and Simulation of Electron Gun for a Multibeam Klystron

    Science.gov (United States)

    Nehra, A. K.; Gupta, R. K.; Sharma, S. M.; Panda, P. C.; Choyal, Y.; Sharma, R. K.

    2012-11-01

    This paper represents the design of multi-beam (sixty-beam) electron gun and focusing system for high power, compact klystron. The beam voltage is 4 kV with a total beam current of 513 (8.55 × 60) mA which is equally divided among sixty-beam. Each beam has a perveance of 0.033 μP making a total gun perveance of 2.02 μP corresponding to a total beam power of more than 2 kW. The cathode radius is7 mm and individual emitter radius is 0.2 mm having current density 6.7 A/cm2. The design has been accomplished using OPERA 3D code. All beamlets have individual anode as well as BFE and a common focusing system. Potential difference between cathode and anode is 4 kV. A magnetic field of 1200 Gauss is applied along the beam axis. A major challenge for the development of multi-beam klystron is design and technology for the focusing of off-axis beamlets because off-axis beams are at various azimuths.

  10. NASA-Ames vertical gun

    Science.gov (United States)

    Schultz, P. H.

    1984-01-01

    A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

  11. State Gun Policy and Cross-State Externalities: Evidence from Crime Gun Tracing

    OpenAIRE

    Brian Knight

    2013-01-01

    This paper provides a theoretical and empirical analysis of cross-state externalities associated with gun regulations in the context of the gun trafficking market. Using gun tracing data, which identify the source state for crime guns recovered in destination states, we find that firearms in this market tend to flow from states with weak gun laws to states with strict gun laws, satisfying a necessary condition for the existence of cross-state externalities in the theoretical model. We also fi...

  12. State Gun Law Environment and Youth Gun Carrying in the United States.

    Science.gov (United States)

    Xuan, Ziming; Hemenway, David

    2015-11-01

    Gun violence and injuries pose a substantial threat to children and youth in the United States. Existing evidence points to the need for interventions and policies for keeping guns out of the hands of children and youth. (1) To examine the association between state gun law environment and youth gun carrying in the United States, and (2) to determine whether adult gun ownership mediates this association. This was a repeated cross-sectional observational study design with 3 years of data on youth gun carrying from US states. The Youth Risk Behavior Survey comprises data of representative samples of students in grades 9 to 12 from biennial years of 2007, 2009, and 2011. We hypothesized that states with more restrictive gun laws have lower rates of youth gun carrying, and this association is mediated by adult gun ownership. State gun law environment as measured by state gun law score. Youth gun carrying was defined as having carried a gun on at least 1 day during the 30 days before the survey. In the fully adjusted model, a 10-point increase in the state gun law score, which represented a more restrictive gun law environment, was associated with a 9% decrease in the odds of youth gun carrying (adjusted odds ratio [AOR], 0.91 [95% CI, 0.86-0.96]). Adult gun ownership mediated the association between state gun law score and youth gun carrying (AOR, 0.94 [ 95% CI, 0.86-1.01], with 29% attenuation of the regression coefficient from -0.09 to -0.07 based on bootstrap resampling). More restrictive overall gun control policies are associated with a reduced likelihood of youth gun carrying. These findings are relevant to gun policy debates about the critical importance of strengthening overall gun law environment to prevent youth gun carrying.

  13. Temporal Association between Federal Gun Laws and the Diversion of Guns to Criminals in Milwaukee

    OpenAIRE

    Webster, Daniel W.; Vernick, Jon S.; Bulzacchelli, Maria T.; Vittes, Katherine A.

    2012-01-01

    The practices of licensed gun dealers can threaten the safety of urban residents by facilitating the diversion of guns to criminals. In 2003, changes to federal law shielded gun dealers from the release of gun trace data and provided other protections to gun dealers. The 14-month period during which the dealer did not sell junk guns was associated with a 68% reduction in the diversion of guns to criminals within a year of sale by the dealer and a 43% increase in guns diverted to criminals fol...

  14. The case for moderate gun control.

    Science.gov (United States)

    DeGrazia, David

    2014-03-01

    In addressing the shape of appropriate gun policy, this essay assumes for the sake of discussion that there is a legal and moral right to private gun ownership. My thesis is that, against the background of this right, the most defensible policy approach in the United States would feature moderate gun control. The first section summarizes the American gun control status quo and characterizes what I call "moderate gun control." The next section states and rebuts six leading arguments against this general approach to gun policy. The section that follows presents a positive case for moderate gun control that emphasizes safety in the home and society as well as rights whose enforcement entails some limits or qualifications on the right to bear arms. A final section shows how the recommended gun regulations address legitimate purposes, rather than imposing arbitrary restrictions on gun rights, and offers concluding reflections.

  15. Results of the AFWL deflagration gun experiments

    International Nuclear Information System (INIS)

    Hackett, K.E.; Baker, W.L.; Beason, J.D.

    1987-01-01

    The snowplow and deflagration modes of coaxial plasma gun operation have been experimentally investigated and computationally simulated at the Air Force Weapons Laboratory. The snowplow mode occurs when the gun is prefilled to a uniform gas density. The initial breakdown forms near the insulator at the gun breech. It heats the gas and creates a shock wave that travels down the gun, ionizing gas and producing a thin current sheath that travels just behind the shock front. The shock front piles up the gas in front of itself as it moves down the gun - hence the name ''snowplow''. Deflagration occurs when gas is injected into an evacuated gun so that the initial breakdown forms as the gas fills the gun. The ionized gas is accelerated into the vacuum region carrying current and magnetic field with it. A quasi-stationary diffuse discharge develops. Gas still entering the gun is processed through the deflagrating discharge and accelerated out the gun muzzle

  16. High power RF systems for the BNL ERL project

    Energy Technology Data Exchange (ETDEWEB)

    Zaltsman, A.; Lambiase, R.

    2011-03-28

    The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a two-way power splitter. The second RF system is for the 703.75 MHz superconducting cavity. The system accelerates the beam to 54.7 MeV and recovers this energy. It will provide up to 50 kW of CW RF power to the cavity. It consists of 50 kW transmitter, circulator, and dummy load. This paper describes the two high power RF systems and presents the test data for both.

  17. A study of an electron gun controlled with a meshless grid for a linear accelerator

    International Nuclear Information System (INIS)

    Homma, Akira; Nakata, Katsuhide; Sawamura, Teruko; Narita, Masakuni

    1996-01-01

    An electron gun for a linear accelerator with a control grid of meshless electrode (meshless grid) is expected to overcome some disadvantages of beam quality using an ordinary mesh grid. A gun of this type was designed and its characteristics were numerically analyzed. The simulation program code Egn2 with a boundary setting routine POLYGON was used. The result indicated that the grid can control the beam launched from the cathode to the anode electrode. It also indicated the Ip-Vp and Ip-Vp characteristics which are different from an ordinary triode gun with a mesh-grid. The mutual conductance gm of 0.4[mS], the maximum average current of 1.6[A] and cut-off voltage -200[V] were obtained under a condition of 200[kV] acceleration voltage. (author)

  18. Large Bore Powder Gun Qualification (U)

    Energy Technology Data Exchange (ETDEWEB)

    Rabern, Donald A. [Los Alamos National Laboratory; Valdiviez, Robert [Los Alamos National Laboratory

    2012-04-02

    A Large Bore Powder Gun (LBPG) is being designed to enable experimentalists to characterize material behavior outside the capabilities of the NNSS JASPER and LANL TA-55 PF-4 guns. The combination of these three guns will create a capability to conduct impact experiments over a wide range of pressures and shock profiles. The Large Bore Powder Gun will be fielded at the Nevada National Security Site (NNSS) U1a Complex. The Complex is nearly 1000 ft below ground with dedicated drifts for testing, instrumentation, and post-shot entombment. To ensure the reliability, safety, and performance of the LBPG, a qualification plan has been established and documented here. Requirements for the LBPG have been established and documented in WE-14-TR-0065 U A, Large Bore Powder Gun Customer Requirements. The document includes the requirements for the physics experiments, the gun and confinement systems, and operations at NNSS. A detailed description of the requirements is established in that document and is referred to and quoted throughout this document. Two Gun and Confinement Systems will be fielded. The Prototype Gun will be used primarily to characterize the gun and confinement performance and be the primary platform for qualification actions. This gun will also be used to investigate and qualify target and diagnostic modifications through the life of the program (U1a.104 Drift). An identical gun, the Physics Gun, will be fielded for confirmatory and Pu experiments (U1a.102D Drift). Both guns will be qualified for operation. The Gun and Confinement System design will be qualified through analysis, inspection, and testing using the Prototype Gun for the majority of process. The Physics Gun will be qualified through inspection and a limited number of qualification tests to ensure performance and behavior equivalent to the Prototype gun. Figure 1.1 shows the partial configuration of U1a and the locations of the Prototype and Physics Gun/Confinement Systems.

  19. A new two-step tuning procedure for a photocathode gun

    International Nuclear Information System (INIS)

    Lal, Shankar; Pant, K.K.; Krishnagopal, S.

    2008-01-01

    An important aspect of the development of multi-cell RF accelerating structures is tuning the resonant frequency f of the operating mode, field balance e b , and waveguide to cavity coupling coefficient β to the desired values. Earlier theoretical analyses have not been able to predict all three parameters simultaneously for a coupled-cavity system. We have developed a generalized circuit analysis to predict f, e b , and β of a coupled structure, based on the RF properties of the individual, uncoupled, cells. This has been used to develop a simplified two-step tuning procedure to tune a BNL/SLAC/UCLA type 1.6 cell S-band photocathode gun by varying RF properties of individual half and full cells, which are easily measurable. This procedure has been validated by tuning two true-to-scale prototypes made of aluminum and ETP copper to the desired values of the RF parameters

  20. Microfluidic stretchable RF electronics.

    Science.gov (United States)

    Cheng, Shi; Wu, Zhigang

    2010-12-07

    Stretchable electronics is a revolutionary technology that will potentially create a world of radically different electronic devices and systems that open up an entirely new spectrum of possibilities. This article proposes a microfluidic based solution for stretchable radio frequency (RF) electronics, using hybrid integration of active circuits assembled on flex foils and liquid alloy passive structures embedded in elastic substrates, e.g. polydimethylsiloxane (PDMS). This concept was employed to implement a 900 MHz stretchable RF radiation sensor, consisting of a large area elastic antenna and a cluster of conventional rigid components for RF power detection. The integrated radiation sensor except the power supply was fully embedded in a thin elastomeric substrate. Good electrical performance of the standalone stretchable antenna as well as the RF power detection sub-module was verified by experiments. The sensor successfully detected the RF radiation over 5 m distance in the system demonstration. Experiments on two-dimensional (2D) stretching up to 15%, folding and twisting of the demonstrated sensor were also carried out. Despite the integrated device was severely deformed, no failure in RF radiation sensing was observed in the tests. This technique illuminates a promising route of realizing stretchable and foldable large area integrated RF electronics that are of great interest to a variety of applications like wearable computing, health monitoring, medical diagnostics, and curvilinear electronics.

  1. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

  2. Geolocation of RF signals

    CERN Document Server

    Progri, Ilir

    2011-01-01

    ""Geolocation of RF Signals - Principles and Simulations"" offers an overview of the best practices and innovative techniques in the art and science of geolocation over the last twenty years. It covers all research and development aspects including theoretical analysis, RF signals, geolocation techniques, key block diagrams, and practical principle simulation examples in the frequency band from 100 MHz to 18 GHz or even 60 GHz. Starting with RF signals, the book progressively examines various signal bands - such as VLF, LF, MF, HF, VHF, UHF, L, S, C, X, Ku, and, K and the corresponding geoloca

  3. Creativity under the gun.

    Science.gov (United States)

    Amabile, Teresa M; Hadley, Constance N; Kramer, Steven J

    2002-08-01

    If you're like most managers, you've worked with people who swear they do their most creative work under tight deadlines. You may use pressure as a management technique, believing it will spur people on to great leaps of insight. You may even manage yourself this way. If so, are you right? Not necessarily, these researchers say. There are instances where ingenuity flourishes under extreme time pressure--for instance, a NASA team within hours comes up with a primitive but effective fix for the failing air filtration system aboard Apollo 13. But when creativity is under the gun, it usually ends up getting killed, the authors say. They recently took a close look at how people experience time pressure, collecting and analyzing more than 9,000 daily diary entries from individuals who were working on projects that required high levels of creativity and measuring their ability to innovate under varying levels of time pressure. The authors describe common characteristics of time pressure and outline four working environments under which creativity may or may not flourish. High-pressure days that still yield creativity are full of focus and meaningful urgency--people feel like they are on a mission. High-pressure days that yield no creativity lack such focus--people feel like they are on a treadmill, forced to switch gears often. On low-pressure days that yield creativity, people feel like they are on an expedition--exploring ideas rather than just identifying problems. And on low-pressure days that yield no creative thinking, people work on autopilot--doing their jobs without engaging too deeply. Managers should avoid extreme time pressure when possible; after all, complex cognitive processing takes time. For when they can't, the authors suggest ways to mollify its effects.

  4. Measurements of intrinsic emittance dependence on rf field for copper photocathodes

    Directory of Open Access Journals (Sweden)

    Eduard Prat

    2015-06-01

    Full Text Available Radio-frequency (rf photoinjectors are used to generate high-brightness electron beams for a wide range of applications. Because of their outstanding beam quality, they are particularly well-suited as sources for X-ray free-electron lasers (FELs. The beam emittance, which is significantly influenced by the intrinsic emittance of the cathode, is fundamental for FELs, since it has a strong impact on the lasing performance and it defines the length and cost of the facility. In this paper we present measurements of the intrinsic emittance as a function of the rf field for a copper photocathode. Our measurements match with the theoretical expectations, showing that the intrinsic emittance can be reduced by decreasing the rf field at the cathode. We obtained normalized intrinsic emittances down to 350  nm/mm, the lowest values ever measured in a rf photoinjector.

  5. Reconfigurable RF Filters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Space Micro proposes to build upon our existing space microelectronics and hardening technologies and products, to research and develop a novel rad hard/tolerant RF...

  6. RF radiation safety handbook

    International Nuclear Information System (INIS)

    Kitchen, Ronald.

    1993-01-01

    Radio frequency radiation can be dangerous in a number of ways. Hazards include electromagnetic compatibility and interference, electro-explosive vapours and devices, and direct effects on the human body. This book is a general introduction to the sources and nature of RF radiation. It describes the ways in which our current knowledge, based on relevant safety standards, can be used to safeguard people from any harmful effects of RF radiation. The book is designed for people responsible for, or concerned with, safety. This target audience will primarily be radio engineers, but includes those skilled in other disciplines including medicine, chemistry or mechanical engineering. The book covers the problems of RF safety management, including the use of measuring instruments and methods, and a review of current safety standards. The implications for RF design engineers are also examined. (Author)

  7. Handmade guns in Trabzon, Turkey.

    Science.gov (United States)

    Yilmaz, Riza; Birincioğlu, Ismail; Uner, H Bulent; Erkol, Zerrin; Butun, Celal; Acikgoz, Dinc; Bulut, Erkut R

    2009-07-01

    A wide variety of handmade firearms have been involved in criminal cases in the city of Trabzon, Turkey. Although they are often very similar to commercially manufactured firearms in terms of design, loading and locking mechanisms, and cocking and firing arrangements, these guns are constructed from cheap materials and are not safe for firing. Handmade firearms manufactured in the Black Sea region of Turkey, particularly in the city of Trabzon, are similar to pistols manufactured by Browning, Luger, Star, Smith and Wesson, Berretta, and MAB. A total of 201 handmade guns referred to the Criminal Police Laboratories for examination from 2003 to 2005 were evaluated with respect to type, number of barrels, size and caliber, rifling, design, mechanism, operability, legality, and similarity to commercial models. We found that most of these handmade guns resembled commercial models in several aspects.

  8. A flat-cathode thermionic injector for the PHERMEX Radiographic Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kauppila, T.; Builta, L.; Burns, M.; Gregory, W.; Honaberger, D.; Watson, S. (Los Alamos National Lab., NM (United States)); Hughes, T. (Mission Research Corp., Albuquerque, NM (United States))

    1993-01-01

    The PHERMEX (Pulsed High-Energy Radiographic Machine Emitting X-rays) standing-wave linear accelerator is a high-current electron beam generator used for flash-radiography. An improved electron gun has been designed employing a flat-thermionic cathode to replace the existing Pierce-geometry gun. The flat cathode yields increased current with the same applied voltage and cathode area as the Pierce gun. The ISIS code simulations indicate a beam current of 1.5 kA at 600 kV. The new geometry also reduces the probability for high voltage breakdown in the A-K gap. A reentrant magnet captures the expanding electron beam and a bucking coil nulls cathode-tinge field. A third coil is used to optimize the extraction field profile and reduce the effect of nonlinear space charge on the beam emittance. Time-resolved measurements of beam current and voltage have been made. In addition, a streak camera was used to measure beam emittance and spatial profile. Comparisons of measurements with simulations are presented.

  9. A flat-cathode thermionic injector for the PHERMEX Radiographic Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kauppila, T.; Builta, L.; Burns, M.; Gregory, W.; Honaberger, D.; Watson, S. [Los Alamos National Lab., NM (United States); Hughes, T. [Mission Research Corp., Albuquerque, NM (United States)

    1993-06-01

    The PHERMEX (Pulsed High-Energy Radiographic Machine Emitting X-rays) standing-wave linear accelerator is a high-current electron beam generator used for flash-radiography. An improved electron gun has been designed employing a flat-thermionic cathode to replace the existing Pierce-geometry gun. The flat cathode yields increased current with the same applied voltage and cathode area as the Pierce gun. The ISIS code simulations indicate a beam current of 1.5 kA at 600 kV. The new geometry also reduces the probability for high voltage breakdown in the A-K gap. A reentrant magnet captures the expanding electron beam and a bucking coil nulls cathode-tinge field. A third coil is used to optimize the extraction field profile and reduce the effect of nonlinear space charge on the beam emittance. Time-resolved measurements of beam current and voltage have been made. In addition, a streak camera was used to measure beam emittance and spatial profile. Comparisons of measurements with simulations are presented.

  10. Microbunching and RF Compression

    International Nuclear Information System (INIS)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-01-01

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  11. Automatic targeting of plasma spray gun

    International Nuclear Information System (INIS)

    Abbatiello, L.A.; Neal, R.E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is described. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun

  12. RF Measurement Concepts

    CERN Document Server

    Caspers, F

    2014-01-01

    For the characterization of components, systems and signals in the radiofrequency (RF) and microwave ranges, several dedicated instruments are in use. In this article the fundamentals of the RF signal techniques are discussed. The key element in these front ends is the Schottky diode which can be used either as a RF mixer or as a single sampler. The spectrum analyser has become an absolutely indispensable tool for RF signal analysis. Here the front end is the RF mixer as the RF section of modern spectrum analyses has a ra ther complex architecture. The reasons for this complexity and certain working principles as well as limitations are discussed. In addition, an overview of the development of scalar and vector signal analysers is given. For the determination of the noise temperature of a one-port and the noise figure of a two-port, basic concepts and relations are shown as well as a brief discussion of commonly used noise-measurement techniques. In a further part of this article the operating principles of n...

  13. Unintentional Gun Deaths among Children. Firearm Facts.

    Science.gov (United States)

    Duker, Laurie, Ed.

    Children are at risk of being killed or injured by a gun if their parents own a gun because many guns obtained for self-defense are kept loaded and within reach of children. This brief fact sheet presents statistical information relating to accidental deaths involving young people and firearms. Safety measures are suggested for preventing…

  14. Design, development and characterization of tetrode type electron gun system for generation of low energy electrons

    International Nuclear Information System (INIS)

    Deore, A.V.; Bhoraskar, V.N.; Dhole, S.D.

    2011-01-01

    A tetrode type electron gun system for the generation of low energy electrons was designed, developed and characterized. An electron gun having four electrodes namely cathode, focusing electrode, control electrode and anode has been designed for the irradiation experiments. This electron gun is capable to provide electrons of energy over the range of 1 keV to 20 keV, with current maximum upto 100 μA. The electron gun and a faraday cup are mounted in the evacuated cylindrical chamber. The samples are fixed on the faraday cup and irradiated with low energy electrons at a pressure around 10 -6 mbar. In this electron gun system, at any electron energy over the entire range, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. Also, the circular shape of the beam spot was maintained, even though the beam current and beam diameter are varied. The uniformity of the electron beam over the entire beam area was measured with a multi electrode assembly and found to be well within 15%. This system is being used for the synthesis and diffusion of metal and semiconductor nanoparticles in polymeric materials. (author)

  15. Magnetron injection gun design for a Q-band 300 kW 30 A gyrotron traveling wave tube

    Science.gov (United States)

    Dong, Kun; Luo, Yong; Yan, Ran; Wang, Shafei

    2015-09-01

    This paper is intended to present the optimal design of a triode type magnetron injection gun (MIG) for a 300 kW, 30 A gyrotron traveling wave tube (gyro-TWT), which is operated at Q band fundamental TE01 mode. Based on the analysis of velocity ratio (VR) distribution along the emission strip (ES), a further optimization of cathode geometry on the basis of a preliminary optimized gun is performed, and a new cathode structure is proposed. Compared with initial optimal parameters, the new structure demonstrates a decline of transverse velocity spread (TVS) from 3.66% to 0.57% and longitudinal velocity spread (LVS) from 4.11% to 0.72%, while VR is maintained at 1.05. The achieved overall LVS reaches as low as 3.44% when considering cathode surface roughness and thermal temperature effect. The sensitivity study has been carried out by changing the gun parameters like anode voltage, beam current, and cathode magnetic field to ensure the practical operation stability.

  16. Youth, guns, and violent crime.

    Science.gov (United States)

    Blumstein, Alfred

    2002-01-01

    Young people are overrepresented as both victims and perpetrators of violence. Indeed, some commentators have suggested that recent cohorts of youth have been composed of "superpredators" who have little regard for human life. The evidence, however, suggests that other factors are responsible for recent increases in youth gun violence. This article analyzes the extent and causes of youth violence in the United States, paying particular attention to the late 1980s and early 1990s, when rates of homicide and robbery committed by youth rose to extremely high levels. Examination of trends for these crimes shows that: The increase in violence in the United States during the late 1980s and early 1990s was due primarily to an increase in violent acts committed by people under age 20. Similarly, dramatic declines in homicide and robbery in recent years are attributable primarily to a decline in youth violence. The increase in youth homicide was predominantly due to a significant increase in the use of handguns, which converted ordinary teenage fights and other violent encounters into homicides. Several other interrelated factors also fueled the rise in youth violence, including the rise of illegal drug markets, particularly for crack cocaine, the recruitment of youth into those markets, and an increase in gun carrying among young people. The author points out that youth violence diminished as the crack markets shrank, law enforcement increased efforts to control youth access to guns, youth gun carrying declined, and the robust economy provided legitimate jobs for young people.

  17. Flit-gun sprayer characteristics

    Directory of Open Access Journals (Sweden)

    J. R. Brown

    1998-05-01

    Full Text Available Six flit-gun sprayers were tested for possible use in mosquito adulticide programs where inexpensive nonmotorized application technology may be required. An analysis of variance for differences in droplets or = 48 µ, droplets/cm², volume median diameters, and mosquito mortality is provided. As shown by these data, good results can be achieved with this equipment.

  18. Electric rail gun application to space propulsion

    International Nuclear Information System (INIS)

    Barber, J.P.

    1979-01-01

    The paper examines the possibility of using the DC electric gun principles as a space vehicle propulsion system, capable of producing intermediate thrust levels. The application of an electromagnetic launch technique, called the DC electric rail gun, to the space propulsion concept of O'Neill, is examined. It is determined that the DC electric rail gun offers very high projectile accelerations and a very significant potential for reducing the size and mass of a reaction motor for space application. A detailed description of rail gun principles is given and some simple expressions for the accelerating force, gun impedance, power supply requirements, and system performance are discussed

  19. Design and test results of the Low Energy Demonstration Accelerator (LEDA) RF systems

    International Nuclear Information System (INIS)

    Rees, D.; Bradley, J. III; Cummings, K.; Lynch, M.; Regan, A.; Rohlev, T.; Roybal, W.; Wang, Y.M.

    1998-01-01

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos will serve as the prototype for the low energy section of the Accelerator Production of Tritium (APT) accelerator. The APT accelerator requires over 200 RF systems each with a continuous wave output power of 1 MW. The reliability and availability of these RF systems is critical to the successful operation of the APT plant and prototypes of these systems are being developed and demonstrated on LEDA. The RF system design for LEDA includes three, 1.2 MW, 350 MHz continuous wave (CW), RF systems driving a radio frequency quadrupole (RFQ) and one, 1.0 MW, CW, RF system driving a coupled-cavity drift tube linac (CCDTL). This paper presents the design and test results for these RF systems including the klystrons, cathode power supply, circulators, RF vacuum windows, accelerator field and resonance control system, and RF transmission components. The three RF systems driving the RFQ use the accelerating structure as a power combiner, and this places some unique requirements on the RF system. These requirements and corresponding operational implications will be discussed

  20. Study of beam transverse properties of a thermionic electron gun for application to a compact THz free electron laser

    International Nuclear Information System (INIS)

    Hu, Tongning; Qin, Bin; Tan, Ping; Chen, Qushan; Yang, Lei; Pei, Yuanji; Li, Ji

    2014-01-01

    A novel thermionic electron gun adopted for use in a high power THz free electron laser (FEL) is proposed in this paper. By optimization of the structural and radiofrequency (RF) parameters, the physical design of the gun is performed using dynamic calculations. Velocity bunching is used to minimize the bunch's energy spread, and the dynamic calculation results indicate that high quality beams can be provided. The transverse properties of the beams generated by the gun are also analyzed. The novel RF focusing effects of the resonance cavity are investigated precisely and are used to establish emittance compensation, which enables the injector length to be reduced. In addition, the causes of the extrema of the beam radius and the normalized transverse emittance are analyzed and interpreted, respectively, and slice simulations are performed to illustrate how the RF focusing varies along the bunch length and to determine the effects of that variation on the emittance compensation. Finally, by observation of the variations of the beam properties in the drift tube behind the electron gun, prospective assembly scenarios for the complete THz-FEL injector are discussed, and a joint-debugging process for the injector is implemented

  1. Commissioning of the 112 MHz SRF Gun and 500 MHz bunching cavities for the CeC PoP Linac

    Energy Technology Data Exchange (ETDEWEB)

    Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Brutus, J. C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Litvinenko, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); McIntosh, P. [Science and Technology Facilities Council (STFC), Daresbury (United Kingdom). Daresbury Lab.; Moss, A. [Science and Technology Facilities Council (STFC), Daresbury (United Kingdom). Daresbury Lab.; Narayan, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Orfin, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pinayev, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rao, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Smith, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Than, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tuozzolo, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wheelhouse, A. [Science and Technology Facilities Council (STFC), Daresbury (United Kingdom). Daresbury Lab.; Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States); Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Xin, T. [Stony Brook Univ., NY (United States); Xu, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zaltsman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    The Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment at BNL includes a short electron linac. During Phase 1, a 112 MHz superconducting RF photo-emission gun and two 500 MHz normal conducting bunching cavities were installed and are under commissioning. The paper describes the Phase1 linac layout and presents commissioning results for the cavities and associated RF, cryogenic and other sub-systems

  2. Crane RF accelerator for high current radiation damage studies

    International Nuclear Information System (INIS)

    Whitham, K.; Anamkath, H.; Evans, K.; Lyons, S.; Palmer, D.; Miller, R.; Treas, P.; Zante, T.

    1992-01-01

    An electron accelerator was designed and built for the Naval Weapons Support Center for transient radiation effects on electronics experiments and testing. The Crane L Band RF Electron Linac was designed to provide high currents over a wide range of pulse widths and energies. The energy extends to 60 MeV and pulse widths vary from a few ns to 10 μsec. Beam currents range from 20 amps in the short pulse case to 1.5 amps in the long pulse case. This paper describes the linac, its architecture, the e-gun and pulser, waveguides, klystrons and modulator, vacuum system, beam transport, and control systems. fig., tab

  3. Basics of RF electronics

    CERN Document Server

    Gallo, A

    2011-01-01

    RF electronics deals with the generation, acquisition and manipulation of high-frequency signals. In particle accelerators signals of this kind are abundant, especially in the RF and beam diagnostics systems. In modern machines the complexity of the electronics assemblies dedicated to RF manipulation, beam diagnostics, and feedbacks is continuously increasing, following the demands for improvement of accelerator performance. However, these systems, and in particular their front-ends and back-ends, still rely on well-established basic hardware components and techniques, while down-converted and acquired signals are digitally processed exploiting the rapidly growing computational capability offered by the available technology. This lecture reviews the operational principles of the basic building blocks used for the treatment of high-frequency signals. Devices such as mixers, phase and amplitude detectors, modulators, filters, switches, directional couplers, oscillators, amplifiers, attenuators, and others are d...

  4. ISR RF cavities

    CERN Multimedia

    1983-01-01

    In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

  5. Conventional RF system design

    International Nuclear Information System (INIS)

    Puglisi, M.

    1994-01-01

    The design of a conventional RF system is always complex and must fit the needs of the particular machine for which it is planned. It follows that many different design criteria should be considered and analyzed, thus exceeding the narrow limits of a lecture. For this reason only the fundamental components of an RF system, including the generators, are considered in this short seminar. The most common formulas are simply presented in the text, while their derivations are shown in the appendices to facilitate, if desired, a more advanced level of understanding. (orig.)

  6. Granny, (don't) get your gun: competency issues in gun ownership by older adults.

    Science.gov (United States)

    Greene, Edith; Bornstein, Brian H; Dietrich, Hannah

    2007-01-01

    This article explores the possible risks associated with gun ownership by older adults. We summarize existing regulations on who may own firearms, especially with respect to age. We then present data on older gun owners and violence committed by older adults in general, followed by a discussion of gun violence perpetrated by gun owners whose functional and cognitive abilities have declined, perhaps as a result of dementia. For comparison purposes, we review regulations on driving among older adults, drawing parallels to gun ownership. The paper concludes with recommendations for ensuring the safety of older gun owners and others, balanced against citizens' right to bear arms, and with some directions for research.

  7. Tha AGS Booster high frequency rf system

    International Nuclear Information System (INIS)

    Sanders, R.; Cameron, P.; Damn, R.

    1988-01-01

    A high level rf system, including a power amplifier and cavity has been designed for the AGS Booster. It covers a frequency range of 2.4 to 4.2 Mhz and will be used to accelerate high intensity proton, and low intensity polarized proton beams to 1.5 GeV and heavy ions to 0.35 GeV per nucleon. A total accelerating voltage of up to 90kV will be provided by two cavities, each having two gaps. The internally cross-coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate the high beam intensity, up to 0.75 /times/ 10 13 protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two paralleled cells. The amplifier is a grounded cathode configuration driven by a remotely located solid state amplifier

  8. The AGS booster high frequency rf system

    International Nuclear Information System (INIS)

    Sanders, R.; Cameron, P.; Kamn, R.; Goldman, M.; Jablonski, E.; Keane, J.; McNerney, A.; Meth, M.; Plotkin, M.; Puglisi, M.; Ratti, A.

    1988-01-01

    This paper reports on a high level RF system, which includes a power amplifier and cavity designed for the AGS Booster. It covers a frequency range of 2.4 to 4.2 MHz and will be used to accelerate high intensity proton, and low intensity polarized proton beams to 1.5 GeV and heavy ions to 0.35 GeV per nucleon. A total accelerating voltage of up to 90kV will be provided by two cavities, each having two gaps. The internally cross-coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate the high beam intensity, up to 0.75 x 10 13 protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two paralleled cells. The amplifier is a grounded cathode configuration driven by a remotely located solid state amplifier

  9. Beam emittance and the effects of the rf, space charge and wake fields: Application to the ATF photoelectron beam

    International Nuclear Information System (INIS)

    Parsa, Z.

    1991-01-01

    Laser driven photoelectron guns are of interest for use in new methods of accelerations, future development of Linear Colliders and new experiments such as Free Electron laser (IFEL). Such guns are potential source of low emittance-high current and short bunch length electron beams, where the emitted electrons are accelerated quickly to a relativistic energy by a strong rf, electric field in the cavity. We present a brief overview of the beam dynamic studies, e.g. emittance for the Brookhaven National Laboratory (BNL) ATF high brightness photocathode radio frequency gun (now in operation), and show the effects of the rf, Space Charge, and Wake fields on the photoelectrons. 4 refs., 7 figs

  10. Modeling and design of an X-band rf photoinjector

    Directory of Open Access Journals (Sweden)

    R. A. Marsh

    2012-10-01

    Full Text Available A design for an X-band rf photoinjector that was developed jointly by SLAC National Accelerator Laboratory (SLAC and Lawrence Livermore National Laboratory (LLNL is presented. The photoinjector is based around a 5.59 cell rf gun that has state-of-the-art features including: elliptical contoured irises; improved mode separation; an optimized initial half cell length; a racetrack input coupler; and coupling that balances pulsed heating with cavity fill time. Radio-frequency and beam dynamics modeling have been done using a combination of codes including PARMELA, HFSS, IMPACT-T, ASTRA, and the ACE3P suite of codes developed at SLAC. The impact of lower gradient operation, magnet misalignment, solenoid multipole errors, beam offset, mode beating, wakefields, and beam line symmetry have been analyzed and are described. Fabrication and testing plans at both LLNL and SLAC are discussed.

  11. Optimization of RF Compressor in the SPARX Injector

    CERN Document Server

    Ronsivalle, Concetta; Ferrario, Massimo; Serafini, Luca; Spataro, Bruno

    2005-01-01

    The SPARX photoinjector consists in a rf gun injecting into three SLAC accelerating sections, the first one operating in the RF compressor configuration in order to achieve higher peak current. A systematic study based on PARMELA simulations has been done in order to optimize the parameters that influence the compression also in view of the application of this system as injector of the so called SPARXINO 3-5 nm FEL test facility. The results of computations show that peak currents at the injector exit up to kA level are achievable with a good control of the transverse and longitudinal emittance by means of a short SW section operating at 11424 MHz placed before the first accelerating section. Some working points in different compression regimes suitable for FEL experiments have been selected. The stability of these points and the sensitivity to various types of random errors are discussed.

  12. Remote RF Battery Charging

    NARCIS (Netherlands)

    Visser, H.J.; Pop, V.; Op het Veld, J.H.G.; Vullers, R.J.M.

    2011-01-01

    The design of a remote RF battery charger is discussed through the analysis and design of the subsystems of a rectenna (rectifying antenna): antenna, rectifying circuit and loaded DC-to-DC voltage (buck-boost) converter. Optimum system power generation performance is obtained by adopting a system

  13. RF power amplifiers

    CERN Document Server

    Albulet, Mihai

    2001-01-01

    This text presents a full account of RF amplifiers and provides a thorough understanding of power amplifier principles and their applications. This comprehensive book covers all important design techniques for power amplifiers and includes mathematical derivations and the assumptions used to develop design rules.

  14. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  15. RF CMOS reliability simulations

    NARCIS (Netherlands)

    Sasse, G.T.; Acar, M.; Kuper, F.G.; Schmitz, Jurriaan

    2008-01-01

    We present a simulation approach to assess the reliability of an RF CMOS circuit under user conditions, based on existing DC degradation models for gate-oxide breakdown and hot-carrier degradation. The simulator allows for lifetime prediction of circuits that can withstand multiple breakdown events.

  16. Effects of Exposure to Gun Violence in Movies on Children's Interest in Real Guns.

    Science.gov (United States)

    Dillon, Kelly P; Bushman, Brad J

    2017-11-01

    More US children die by accidental gun use than children in other developed countries. One factor that can influence children's interest in guns is exposure to media containing guns. To test whether children who see a movie containing guns will handle a real gun longer and will pull the trigger more times than children who see the same movie not containing guns. One hundred four children aged 8 to 12 years recruited through advertisements were randomly assigned in pairs to watch a 20-minute PG-rated movie containing or not containing guns in a university laboratory. Children then played with toys and games in a room for 20 minutes while being video recorded. A cabinet in the room contained a real (disabled) gun with a sensor counting trigger pulls. Recordings were coded for the time spent holding the gun and in aggressive play. Data were collected from July 15, 2015, through January 1, 2016, and analyzed using generalized estimating equations (Tweedie log-link for time spent holding the gun; Poisson log-link for pulling the trigger). The 2 main outcomes were time spent holding the gun and the number of trigger pulls. Control variables included sex, age, trait aggressiveness, exposure to violent media, interest in guns, and number of guns at home. Among the 104 study participants (62 boys [59.6%] and 42 girls [40.4%]; mean (SD) age, 9.9 [1.5] years), the adjusted median number of trigger pulls among children who saw the movie containing guns was 2.8 (interquartile range [IQR], 0.2-2.8) compared with 0.01 (IQR, 0.01-0.2) among children who saw the movie not containing guns (adjusted odds ratio, 22.3; 95% CI, 6.0-83.4; P gun among children who saw a movie containing guns was 53.1 (IQR, 35.5-53.1) compared with 11.1 (IQR, 10.7-16.7) among children who saw the movie not containing guns (adjusted odds ratio, 3.0; 95% CI, 0.9-9.9; P = .07). Qualitative analyses on 4 pairs from each condition found that children who saw the movie containing guns also played more

  17. Guns, Suicide, COPD and Sleep

    Directory of Open Access Journals (Sweden)

    Robbins RA

    2018-03-01

    Full Text Available No abstract available. Article truncated at 150 words. Within the past year two tragic events, the shootings in Las Vegas and Florida have renewed the debate about guns. The politics and the money that fuels the political debate have sharply divided politicians. As tragic as these mass shootings are, deaths by suicide far outnumber the loss of live in these shootings. In 2014 suicide was the tenth most common cause of death with 42,826 lives lost (1. Half of the suicides were by firearm (21,386. The medical profession has traditionally been reluctant to speak about politically sensitive issues such as abortion, sexuality, and guns. However, beginning early in this millennium some medical societies such as the American Academy of Pediatrics, the US Preventative Services Task Force and even the Department of Veterans Affairs were suggesting physicians ask patients about gun behavior, but a few patients complained (2-5. There were some anecdotal reports of patients feeling “pressured” to answer …

  18. Introduction to RF linear accelerators

    CERN Document Server

    Pichoff, N

    2006-01-01

    After a short introduction to applications of RF linacs and their advantages and drawbacks as opposed to circular accelerators, the model of RF resonant cavities and their excitation by RF sources or beam is introduced. Then beam dynamics notions, essential to linacs, such as transit-time factor, synchronism, r.m.s. properties, matching and mismatching in linear or nonlinear forces, are presented.

  19. Flat-beam Rf photocathode sources for linear collider applications

    International Nuclear Information System (INIS)

    Rosenzweig, J.B.

    1991-01-01

    Laser driven rf photocathodes represent a recent advance in high-brightness electron beam sources. The authors investigate here a variation on these devices, that obtained by using a ribbon laser pulse to illuminate the cathode, yielding a flat beam (σ x much-gt σ y ) which has asymmetric emittances at the cathode proportional to the beam size each transverse dimension. The flat-beam geometry mitigates space charge forces which lead to intensity dependent transverse and longitudinal emittance growth, thus limiting the beam brightness. The fundamental limit on achievable emittance and brightness is set by the transverse momentum distribution and peak current density of the photoelectrons (photon energy and cathode material dependent effects) and appears to allow, taking into account space charge and rf effects, normalized emittances ε x -5 m-rad and ε -6 m-rad, with Q = 5 nC and σ z = 1 mm. These source emittances are adequate for superconducting linear collider applications, and could preclude the use of a damping ring for the electrons in these schemes

  20. RF phase focusing in portable X-band, linear accelerators

    International Nuclear Information System (INIS)

    Miller, R.H.; Deruyter, H.; Fowkes, W.R.; Potter, J.W.; Schonberg, R.G.; Weaver, J.W.

    1985-01-01

    In order to minimize the size and weight of the x-ray or neutron source for a series of portable radiographic linear accelerators, the x-ray head was packaged separately from the rest of the system and consists of only the linac accelerating structure, electron gun, built-in target, collimator, ion pump and an RF window. All the driving electronics and cooling are connected to the x-ray head through flexible waveguide, cables, and waterlines. The x-ray head has been kept small and light weight by using the RF fields for radial focusing, as well as for longitudinal bunching and accelerating the beam. Thus, no external, bulky magnetic focusing devices are required. The RF focusing is accomplished by alternating the sign of the phase difference between the RF and the beam and by tapering from cavity to cavity the magnitude of the buncher field levels. The former requires choosing the right phase velocity taper (mix of less than vp=c cavities) and the latter requires the right sizing of the cavity to cavity coupling smiles (irises)

  1. Racism, gun ownership and gun control: biased attitudes in US whites may influence policy decisions.

    Directory of Open Access Journals (Sweden)

    Kerry O'Brien

    Full Text Available OBJECTIVE: Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty. This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. METHOD: The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. RESULTS: After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58 was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46, which likely represents self-interest in retaining property (guns. CONCLUSIONS: Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.

  2. Racism, Gun Ownership and Gun Control: Biased Attitudes in US Whites May Influence Policy Decisions

    OpenAIRE

    O?Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael

    2013-01-01

    OBJECTIVE: Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. METHOD: The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US wh...

  3. Guns, Crime, and Academics: Some Reflections on the Gun Control Debate.

    OpenAIRE

    Parker, Jeffrey S

    2001-01-01

    This comment on Thomas Marvell's "The Impact of Banning Juvenile Gun Possession" analyzes Marvell's empirical findings and their policy implications for gun control legislation. While Marvell's article stresses the absence of any finding favorable to juvenile gun bans, this comment points out that the statistical results actually support the stronger finding that some of the juvenile gun bans are associated with a statistically significant increase in homicides nationwide. Under either findin...

  4. Racism, Gun Ownership and Gun Control: Biased Attitudes in US Whites May Influence Policy Decisions

    Science.gov (United States)

    O’Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael

    2013-01-01

    Objective Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. Method The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification) were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. Results After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58) was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46), which likely represents self-interest in retaining property (guns). Conclusions Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites’ paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions. PMID:24204867

  5. Racism, gun ownership and gun control: biased attitudes in US whites may influence policy decisions.

    Science.gov (United States)

    O'Brien, Kerry; Forrest, Walter; Lynott, Dermot; Daly, Michael

    2013-01-01

    Racism is related to policies preferences and behaviors that adversely affect blacks and appear related to a fear of blacks (e.g., increased policing, death penalty). This study examined whether racism is also related to gun ownership and opposition to gun controls in US whites. The most recent data from the American National Election Study, a large representative US sample, was used to test relationships between racism, gun ownership, and opposition to gun control in US whites. Explanatory variables known to be related to gun ownership and gun control opposition (i.e., age, gender, education, income, conservatism, anti-government sentiment, southern vs. other states, political identification) were entered in logistic regression models, along with measures of racism, and the stereotype of blacks as violent. Outcome variables included; having a gun in the home, opposition to bans on handguns in the home, support for permits to carry concealed handguns. After accounting for all explanatory variables, logistic regressions found that for each 1 point increase in symbolic racism there was a 50% increase in the odds of having a gun at home. After also accounting for having a gun in the home, there was still a 28% increase in support for permits to carry concealed handguns, for each one point increase in symbolic racism. The relationship between symbolic racism and opposition to banning handguns in the home (OR1.27 CI 1.03,1.58) was reduced to non-significant after accounting for having a gun in the home (OR1.17 CI.94,1.46), which likely represents self-interest in retaining property (guns). Symbolic racism was related to having a gun in the home and opposition to gun control policies in US whites. The findings help explain US whites' paradoxical attitudes towards gun ownership and gun control. Such attitudes may adversely influence US gun control policy debates and decisions.

  6. Rate control for electron gun evaporation

    International Nuclear Information System (INIS)

    Schellingerhout, A.J.G.; Janocko, M.A.; Klapwijk, T.M.; Mooij, J.E.

    1989-01-01

    Principles for obtaining high-quality rate control for electron gun evaporation are discussed. The design criteria for rate controllers are derived from this analysis. Results are presented which have been obtained with e-guns whose evaporation rate is controlled by a Wehnelt electrode or by sweeping of the electron beam. Further improvements of rate stability can be obtained by improved design of e-guns and power supplies

  7. Improved Orifice Plate for Spray Gun

    Science.gov (United States)

    Cunningham, W.

    1986-01-01

    Erratic spray pattern of commercial spray gun changed to repeatable one by simple redesign of two parts. In modified spray gun orifice plate and polytetrafluoroethylene bushing redesigned to assure centering and alignment with nozzle. Such improvement useful in many industrial applications requiring repeatable spray patterns. Might include spraying of foam insulation, paint, other protective coatings, detergents, abrasives, adhesives, process chemicals, or fuels. Unmodified spray gun produces erratic spray because lateral misalignment between orifice plate and nozzle.

  8. Gun Control in Australia: A Criminological Perspective

    Directory of Open Access Journals (Sweden)

    Rick Sarre

    2015-11-01

    Full Text Available In recent months there has been an upsurge in contributions to the popular press from social commentators insisting that guns make our nation safer. This essay questions these assertions. The paper provides evidence to support a contrary affirmation: that is, in order to have a reduction in gun violence, there needs to be a reduction in the number of guns generally, and a continuation of the legal controls that currently shape firearms policy in Australia.

  9. STREAK CAMERA MEASUREMENTS OF THE APS PC GUN DRIVE LASER

    Energy Technology Data Exchange (ETDEWEB)

    Dooling, J. C.; Lumpkin, A. H.

    2017-06-25

    We report recent pulse-duration measurements of the APS PC Gun drive laser at both second harmonic and fourth harmonic wavelengths. The drive laser is a Nd:Glass-based chirped pulsed amplifier (CPA) operating at an IR wavelength of 1053 nm, twice frequency-doubled to obtain UV output for the gun. A Hamamatsu C5680 streak camera and an M5675 synchroscan unit are used for these measurements; the synchroscan unit is tuned to 119 MHz, the 24th subharmonic of the linac s-band operating frequency. Calibration is accomplished both electronically and optically. Electronic calibration utilizes a programmable delay line in the 119 MHz rf path. The optical delay uses an etalon with known spacing between reflecting surfaces and is coated for the visible, SH wavelength. IR pulse duration is monitored with an autocorrelator. Fitting the streak camera image projected profiles with Gaussians, UV rms pulse durations are found to vary from 2.1 ps to 3.5 ps as the IR varies from 2.2 ps to 5.2 ps.

  10. Air cathode structure manufacture

    Science.gov (United States)

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  11. Conceptual Design for CLIC Gun Pulser

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Tao [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-01-08

    The Compact Linear Collider (CLIC) is a proposed future electron-positron collider, designed to perform collisions at energies from 0.5 to 5 TeV, with a nominal design optimized for 3 TeV (Dannheim, 2012). The Drive Beam Accelerator consists of a thermionic DC gun, bunching section and an accelerating section. The thermionic gun needs deliver a long (~143us) pulse of current into the buncher. A pulser is needed to drive grid of the gun to generate a stable current output. This report explores the requirements of the gun pulser and potential solutions to regulate grid current.

  12. Health and Gun Violence. Guns as a Public-Health Issue.

    Science.gov (United States)

    Duran, Victoria

    1994-01-01

    Violence in all settings has reached epidemic proportions. Most shootings are committed by friends or relatives following an argument or when playing with guns. The public needs education about nonviolent ways of coping with anger and about the high cost of gun violence. Suggestions for avoiding gun violence and the PTA position on firearms are…

  13. A 20 keV electron gun system for the electron irradiation experiments

    International Nuclear Information System (INIS)

    Mahapatra, S.K.; Dhole, S.D.; Bhoraskar, V.N.

    2005-01-01

    An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 μA. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure ∼10 -7 mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours

  14. Electron Gun and Injector Designs for State-of-the-Art FELs

    CERN Document Server

    Blüm, H P; Christina, V; Cole, M D; Falletta, M; Holmes, D; Peterson, E; Rathke, J; Schultheiss, T; Todd, A M M; Wong, R

    2005-01-01

    Reliable, high-brightness, high-power injector operation is a critical technology issue for energy recovery linac drivers of high-power free electron lasers (FEL). Advanced Energy Systems is involved in three ongoing injector programs that target up to 0.5 Ampere current levels at emittance values consistent with the requirements of the FEL. One is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. A 748.5 MHz injector of this type is being assembled and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility (JLAB) beginning in 2007. The second approach being explored is a high-current normal-conducting RF photoinjector. A 700 MHz gun, presently under fabrication, will undergo thermal test in 2006 at Los Alamos National Laboratory (LANL). Finally, a half-cell 703.75 MHz SRF gun is presently being designed and will be tested to 0.5 Ampere at Brookhaven National Laboratory (BNL) in 2007. The status and projected performance for each of these injector projects is pr...

  15. RF Pulsed Heating

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2002-01-03

    RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  16. Pulsed rf operation analysis

    International Nuclear Information System (INIS)

    Puglisi, M.; Cornacchia, M.

    1981-01-01

    The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated

  17. Systematic study of a simple formation of pierce-electron-gun

    International Nuclear Information System (INIS)

    Saad, Hussein Mahmoud; Abd Elhamed, H.

    1985-01-01

    In this work the design and construction of a simple form of Pierce Gun are discussed. As the vacuum system used in the experiment was frequently exposed to open air, a solenoid filamentary-cathode was used. Hence, an effective magnetic field has been induced as the filament was heated, whereupon the electrons altered their paths. We, therefore investigated the change in beam intensity as influenced by the focusing electrode material, anode position, and extraction hole width. The focusing electrode effect was examined by comparing the measured emission current density with the corresponding calculated value. The studies showed that electrons follow a saddle-like shape in the gun inter-space. It was modified by the stainless steel focusing electrode

  18. Design of a magnetron injection gun for a 17.5-GHz

    International Nuclear Information System (INIS)

    Ha, H. J.; Kim, J. E.; Park, G. S.

    1996-01-01

    A gyrotwystron which is composed of cavities (gyro-klystron) and waveguides (gyro-TWT) is under investigation for broader bandwidth with high efficiency. A magnetron injection gun (MIG) for the gyrotwystron is designed with the trade-off equation for the MIG and optimized by computer simulation using the e-gun code. A 300-kW, 60-kV MIG with α ≡ υ t /υ z = 1.2 and Δυ z ≤ 5% designed for a 17.5-GHz gyrotwystron is discussed in this paper. Also, the effect of various MIG parameters, such as the beam voltage, the beam current, the magnetic field, the cathode radius and angle, and the MIG dimensions, on the characteristics of the beam (α, Δυ z ) is studied. (author)

  19. High-energy electron impact apparatus utilizing a simple diode electron gun assembly

    International Nuclear Information System (INIS)

    Peterson, R.B.; Pidwerbekki, D.

    1992-01-01

    An electron impact facility based on a ribbon filament cathode, simple diode gun, and thin aluminium foil window is described. The facility is designed for the study of gas phase electron impact phenomena at pressures up to one atmosphere in a variety of gases. Of particular interest is the simple design of the electron gun for generating electron beams having energies up to 100 keV and currents up to 5 mA. The beam is magnetically collimated and directed through a thin aluminium foil which is used as the vacuum-gas interface to an impact chamber. Maximum power delivered to the impact region depends on the thickness of the foil window. Using an 8.4 μm thick aluminium foil, approximately 150 W can be delivered to the impact chamber. Thermal heating of the foil by the electron beam is the limiting factor restricting higher effective power transmission. (Author)

  20. Gun shows across a multistate American gun market: observational evidence of the effects of regulatory policies.

    Science.gov (United States)

    Wintemute, Garen J

    2007-06-01

    To describe gun shows and assess the impact of increased regulation on characteristics linked to their importance as sources of guns used in crime. Cross-sectional, observational. Data were collected at a structured sample of 28 gun shows in California, which regulates these events and prohibits undocumented private party gun sales; and in Arizona, Nevada, Texas and Florida-all leading sources of California's crime guns--where these restrictions do not exist. Size of shows, measured by numbers of gun vendors and people in attendance; number and nature of guns for sale by gun vendors; measures of private party gun sales and illegal surrogate ("straw") gun purchases. Shows in comparison states were larger, but the number of attendees per gun vendor was higher in California. None of these differences was statistically significant. Armed attendees were more common in other states (median 5.7%, interquartile range (IQR) 3.9-10.0%) than in California (median 1.1%, IQR 0.5-2.2%), p = 0.0007. Thirty percent of gun vendors both in California and elsewhere were identifiable as licensed firearm retailers. There were few differences in the types or numbers of guns offered for sale; vendors elsewhere were more likely to sell assault weapons (34.9% and 13.3%, respectively; p = 0.001). Straw purchases were more common in the comparison states (rate ratio 6.6 (95% CI 0.9 to 49.1), p = 0.06). California's regulatory policies were associated with a decreased incidence of anonymous, undocumented gun sales and illegal straw purchases at gun shows. No significant adverse effects of these policies were observed.

  1. Experimental studies of coaxial plasma gun current

    International Nuclear Information System (INIS)

    Price, D.W.

    1988-01-01

    In this investigation of a coaxial plasma gun, plasma sheath currents and related behavior are examined. Plasma behavior in the gun affects gun characteristics. Plasma gun applications are determined by the plasma behavior. The AFWL PUFF capacitor bank (72 μF, 29 nH, 120 kV) drives the plasma gun using a deuterium fill gas. The gas breakdown site is isolated from the dielectric/vacuum interface in the AFWL system. Two gas values deliver gas in the system. The first delivers gas from the gun breech and the second optional valve delivers gas to the gun muzzle. Currents and voltages are measured by Rogowski coils, B probes and capacitive voltage probes. A O-D slug model is used to predict the current, inductance, gun voltage and plasma sheath velocity. The slug model assumes the sheath transits the gun with all mass in the sheath. In the snowplow mode, the plasma sheath is thin with a sharp current rise and drop. Our system operated in a transition mode between the snowplow and deflagration modes with early snowplow behavior and late deflagration behavior. Neutrons are produced in a plasma pinch at the gun muzzle, indicating snowplow behavior. The slug theory models overall gun behavior to experimental accuracy. Experimental results are compared to four theories for plasma sheath velocities: the Alfven collisionally limited model, the Rosenbluth model, the Fishbine saturated model and a single particle drift model. Experimental velocities vary from 10 5 to 10 6 m/s. Only the single particle drift and the slug model calculations are of the right magnitude (8 x 10 5 m/s). The Fishbine and the Rosenbluth models predict slower velocities (2 x 10 5 m/s). The Alfven model is not applicable to this system

  2. From gun politics to self-defense politics: a feminist critique of the great gun debate.

    Science.gov (United States)

    Carlson, Jennifer D

    2014-03-01

    This article calls attention to a problematic binary produced by public debates surrounding gun rights and gun control-namely, that women must choose armed self-protection or no self-protection at all. I argue that both anti- and pro-gun discourses, drawing on and reproducing race and class privileges, use assumptions about women's physical inferiority to further their agendas. I highlight how both sides have used guns as the proxy for self-defense and conclude by calling for a shift in public discourse to focus on the broader question of the right to self-defense rather than the narrower question of gun rights.

  3. Clinging to their Guns? The New Politics of Gun Carry in Everyday Life

    OpenAIRE

    Carlson, Jennifer

    2013-01-01

    Alongside a series of high-profile massacres over the past decade, Americans continue to turn to guns as the solution to, rather than the cause of, violent crime. Since the 1970s, most US states have significantly loosened restrictions on gun carrying for self-defense, and today, over 8 million Americans hold permits to carry guns concealed. Contrary to popular images of gun culture, this is not a white-only affair: in Michigan, whites and African Americans are licensed to carry guns at rough...

  4. The Xygra gun simulation tool.

    Energy Technology Data Exchange (ETDEWEB)

    Garasi, Christopher Joseph; Lamppa, Derek C.; Aubuchon, Matthew S.; Shirley, David Noyes; Robinson, Allen Conrad; Russo, Thomas V.

    2008-12-01

    Inductive electromagnetic launchers, or coilguns, use discrete solenoidal coils to accelerate a coaxial conductive armature. To date, Sandia has been using an internally developed code, SLINGSHOT, as a point-mass lumped circuit element simulation tool for modeling coilgun behavior for design and verification purposes. This code has shortcomings in terms of accurately modeling gun performance under stressful electromagnetic propulsion environments. To correct for these limitations, it was decided to attempt to closely couple two Sandia simulation codes, Xyce and ALEGRA, to develop a more rigorous simulation capability for demanding launch applications. This report summarizes the modifications made to each respective code and the path forward to completing interfacing between them.

  5. Simulation of distributed-emission and injected-beam crossed-field amplifiers. Part 2: The crossed-field electron gun

    Science.gov (United States)

    MacGregor, D. M.; Fontana, T. P.; Rowe, J. E.

    1980-04-01

    Numerical models developed for the crossed-field electron gun predict the current and the beam shape and stability for varied voltages or magnetic field. These programs use a deformable triangular mesh to reproduce the realistic electrode boundaries. A static iterative analysis predicts beam currents about 5 percent higher than measured for a short Kino gun, but is not stable for long cathodes with returning electrodes. However, the alternative time-dependent method predicts a stable, well-defined beam in both cases. Excess shot noise in a long-cathode crossed-field gun is believed to be due to cycloiding electrons which return to the cathode from well beyond the potential minimum. Of three theories compared here, only the Ho and Van Duzer model includes these electrons and predicts an instability. With added shot noise the computer simulation may be capable of reproducing the effect. Experimental measurements have been obtained by subcontract for a Northrop gridded crossed-field gun. The two dimensional time-dependent analysis, which ignores the grids, predicts the beam current with good order-of-magnitude agreement.

  6. The Effects of Cueing and Framing on Youth Attitudes towards Gun Control and Gun Rights

    Directory of Open Access Journals (Sweden)

    Stephen Wu

    2018-02-01

    Full Text Available I analyze attitudes towards gun control from a recent survey of American high school students. For students who most closely identify as Republicans, cueing them to think about prior school shootings increases their agreement that armed staff in schools will improve safety and arming citizens will reduce risk of mass shootings. For those identifying as Democrats and Independents, providing them with selective information that certain states have loose gun control laws and low rates of gun violence makes them more supportive of gun rights. For Republicans, providing selective information that certain states have loose gun control laws and high rates of gun violence makes them less supportive of gun rights. These results suggest that emotional cues may exacerbate a priori biases, while informational cues may be more likely to change people’s minds about firearm policies.

  7. Action alters object identification: wielding a gun increases the bias to see guns.

    Science.gov (United States)

    Witt, Jessica K; Brockmole, James R

    2012-10-01

    Stereotypes, expectations, and emotions influence an observer's ability to detect and categorize objects as guns. In light of recent work in action-perception interactions, however, there is another unexplored factor that may be critical: The action choices available to the perceiver. In five experiments, participants determined whether another person was holding a gun or a neutral object. Critically, the participant did this while holding and responding with either a gun or a neutral object. Responding with a gun biased observers to report "gun present" more than did responding with a ball. Thus, by virtue of affording a perceiver the opportunity to use a gun, he or she was more likely to classify objects in a scene as a gun and, as a result, to engage in threat-induced behavior (raising a firearm to shoot). In addition to theoretical implications for event perception and object identification, these findings have practical implications for law enforcement and public safety.

  8. Characteristics of electron emission from PZT ferroelectric cathode under strong accelerating field

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Yasushi [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan)]. E-mail: hayashi@es.titech.ac.jp; Hotta, Eiki [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan); Flechtner, Donald [High Voltage Laboratory, Cornell University, Ithaca, NY (United States)

    2002-02-07

    We have studied emission characteristics of a PZT ferroelectric cathode under the influence of a strong accelerating field by varying the triggering conditions. The beam current pulse reveals a rising and a steady phase. In the rising phase, the time variation of the beam current is found to be linearly dependent on both the trigger voltage and the diode voltage at the time when the current starts. In the steady phase, field emission characteristics are observed. The results show that the diode voltage is not only accelerating the emitted electrons but also assisting the electron emission from the ferroelectric cathode. An empirical model is proposed and is found to yield a reasonable beam current pulse when the electric field on the surface of the cathode is uniformly distributed. It also provides us with a new possibility to diagnose the emission process of a ferroelectric electron gun. (author)

  9. Plasma-gun fueling for tokamak reactors

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1980-11-01

    In light of the uncertain extrapolation of gas puffing for reactor fueling and certain limitations to pellet injection, the snowplow plasma gun has been studied as a fueling device. Based on current understanding of gun and plasma behavior a design is proposed, and its performance is predicted in a tokamak reactor environment

  10. Where have all the gun deaths gone?

    African Journals Online (AJOL)

    Gun violence denialists recently dismissed the findings of two studies presented at a seminar co-hosted by Gun Free South Africa, the. Institute for Security Studies and the African. Policing Civilian Oversight Forum. Abrahams et al.[1] compared the profile of female homicides from two representative national samples.

  11. Fighting Juvenile Gun Violence. Juvenile Justice Bulletin.

    Science.gov (United States)

    Sheppard, David; Grant, Heath; Rowe, Wendy; Jacobs, Nancy

    This bulletin describes the Office of Juvenile Justice and Delinquency Prevention's efforts to fight juvenile gun violence. The Office awarded four community demonstration grants to implement "Partnerships To Reduce Juvenile Gun Violence." Partnership goals include increasing the effectiveness of existing strategies by enhancing and…

  12. Gun Control: The Debate and Public Policy.

    Science.gov (United States)

    Watkins, Christine

    1997-01-01

    Provides an overview and background information on the debate over gun control, as well as several teaching ideas. Handouts include a list of related topics drawn from various disciplines (economics, U.S. history), seven arguments for and against gun control, and a set of policy evaluation guidelines. (MJP)

  13. Depression cathode structure for cathode ray tubes having surface smoothness and method for producing same

    International Nuclear Information System (INIS)

    Rychlewski, T.V.

    1984-01-01

    Depression cathode structures for cathode ray tubes are produced by dispensing liquid cathode material into the depression of a metallic supporting substrate, removing excess cathode material by passing a doctor blade across the substrate surface and over the depression, and drying the cathode layer to a substantially immobile state. The cathode layer may optionally be further shaped prior to substantially complete drying thereof

  14. Synthesis method for ultrananocrystalline diamond in powder employing a coaxial arc plasma gun

    Science.gov (United States)

    Naragino, Hiroshi; Tominaga, Aki; Hanada, Kenji; Yoshitake, Tsuyoshi

    2015-07-01

    A new method that enables us to synthesize ultrananocrystalline diamond (UNCD) in powder is proposed. Highly energetic carbon species ejected from a graphite cathode of a coaxial arc plasma gun were provided on a quartz plate at a high density by repeated arc discharge in a compact vacuum chamber, and resultant films automatically peeled from the plate were aggregated and powdered. The grain size was easily controlled from 2.4 to 15.0 nm by changing the arc discharge energy. It was experimentally demonstrated that the proposed method is a new and promising method that enables us to synthesize UNCD in powder easily and controllably.

  15. Status of RF photoinjector and PWT linac at UCLA

    International Nuclear Information System (INIS)

    Park, S.; Barov, N.; Hartman, S.; Pellegrini, C.; Rosenzweig, J.; Tran, P.; Travish, G.; Zhang, R.; Davis, P.; Hairapetian, G.; Joshi, C.; Luhmann, N.

    1992-01-01

    We report the present status of the rf photoinjector and plane wave transformer (PWT) linac for the production of 20 MeV/c electron beams. The photoinjector is a 1 1/2 cell π-mode standing wave structure operating at 2.856 GHz with photoelectrons generated on a copper cathode by a 4 ps long laser pulse at 266 nm. Measurements of the beam of photoelectrons are underway at various experimental parameters. The PWT has been tested at low power to investigate its mode structure. An overview of the system, latest data, and future directions are presented here. (Author) 3 figs., 5 refs

  16. Cerebral damage caused by nail gun injury

    DEFF Research Database (Denmark)

    Andersen, Chris

    2016-01-01

    Background Accidents with nail guns are rather common, especially in the construction industry. Most injuries involve the extremities and several present with intracerebral injuries. When the patient is unconscious, it can be a big challenge to determine whether the injury is an accident, self....... The forensic examination showed lesions of intracranial surgery and minor bruises on the arms. No sign of defense injuries was found. There were no signs of malfunction of the nail gun-wielding robot. On the side of the machine, there were a handheld nail gun and the police investigated the case as a possible...... criminal act. They found bloodstains on the back of the machine. When awake, the man explained, that by accident, he had hit his head against a nail gun and as a result of this, the nail gun delivered a nail into his skull. Conclusion Sometimes, the circumstances of a case are not clear...

  17. New Electron Gun System for BEPCII

    CERN Document Server

    Liu, Bo; Long Chi, Yun; Zhang, Chuang

    2005-01-01

    The new electron gun system for BEPCII has been put into operation since Nov. 2004. The article describes the design, experiment and operation of this new system. The design current of the gun is 10 A for the pulse lengths of 1 ns, 2.5 ns and 1 μs with repetition rate of 50 Hz. The gun is operated with a pulsed high voltage power supply which can provide up to 200 kV high voltage. Computer simulations have been carried out in the design stage, including simulation of the gun geometry and beam transportation. Some important relation curves are obtained during the experiment. Two-bunch operation is available and some elementary tests have been performed. New scheme of the gun control system based on EPICS is also presented. The real operation shows that the design and manufacturing is basically successful.

  18. Interpreting the empirical evidence on illegal gun market dynamics.

    Science.gov (United States)

    Braga, Anthony A; Wintemute, Garen J; Pierce, Glenn L; Cook, Philip J; Ridgeway, Greg

    2012-10-01

    Thousands of Americans are killed by gunfire each year, and hundreds of thousands more are injured or threatened with guns in robberies and assaults. The burden of gun violence in urban areas is particularly high. Critics suggest that the results of firearm trace data and gun trafficking investigation studies cannot be used to understand the illegal supply of guns to criminals and, therefore, that regulatory and enforcement efforts designed to disrupt illegal firearms markets are futile in addressing criminal access to firearms. In this paper, we present new data to address three key arguments used by skeptics to undermine research on illegal gun market dynamics. We find that criminals rely upon a diverse set of illegal diversion pathways to acquire guns, gun traffickers usually divert small numbers of guns, newer guns are diverted through close-to-retail diversions from legal firearms commerce, and that a diverse set of gun trafficking indicators are needed to identify and shut down gun trafficking pathways.

  19. Observation of the hollow cathode effect from a dielectric cathode

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Hyeon Seok; Oh, Jin Young; Baik, Hong Koo [Department of Advanced Materials Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Youn Sang [Department of Nano Convergence, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, 443-270 (Korea, Republic of); Lee, Se Jong [Department of Advanced Materials Engineering, Kyungsung University, Busan 608-736 (Korea, Republic of); Song, Kie Moon, E-mail: thinfilm@yonsei.ac.k [Department of Applied Physics, Konkuk University, Chungju-Si, 380-701 (Korea, Republic of)

    2010-12-15

    The hollow cathode effect (HCE) is investigated in the dielectric hollow cathode structure in a Ne-Xe mixture at 4%. The influence of the dielectric is shown experimentally by the relationship between voltage and current peaks. The linearity of reduced current density confirms the existence of the HCE and shows that cathode fall has the same value at every pD condition. Varying the pD, the variation in the discharge mode can be measured with IR intensity emitted from the plasma and photographs of discharge in the visible part of the spectra. Voltages and current in the range of 3 kV at 10 {mu}A were used. We suggest an electrode configuration reinforced in cathode sputtering for the display panel and light source using the dielectric hollow cathode discharge (DHCD), and introducing a mechanism of the DHCD mode.

  20. Observation of the hollow cathode effect from a dielectric cathode

    International Nuclear Information System (INIS)

    Hwang, Hyeon Seok; Oh, Jin Young; Baik, Hong Koo; Kim, Youn Sang; Lee, Se Jong; Song, Kie Moon

    2010-01-01

    The hollow cathode effect (HCE) is investigated in the dielectric hollow cathode structure in a Ne-Xe mixture at 4%. The influence of the dielectric is shown experimentally by the relationship between voltage and current peaks. The linearity of reduced current density confirms the existence of the HCE and shows that cathode fall has the same value at every pD condition. Varying the pD, the variation in the discharge mode can be measured with IR intensity emitted from the plasma and photographs of discharge in the visible part of the spectra. Voltages and current in the range of 3 kV at 10 μA were used. We suggest an electrode configuration reinforced in cathode sputtering for the display panel and light source using the dielectric hollow cathode discharge (DHCD), and introducing a mechanism of the DHCD mode.

  1. RF current sensor

    Science.gov (United States)

    Moore, James A.; Sparks, Dennis O.

    1998-11-10

    An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

  2. RF Synthesis without Inductors

    OpenAIRE

    Kong, Long

    2016-01-01

    Recent developments in RF receiver design have eliminated all on-chip inductors except for that used in the local oscillator. This dissertation addresses the “last inductor” problem and proposes both integer-N and fractional-N synthesizer architectures that achieve a phase noise and figure of merit (FOM) comparable to those of LC-VCO-based realizations.A new wideband integer-N synthesizer is introduced to sufficiently suppress the ring’s phase noise. It employs an exclusive-OR (XOR) phase det...

  3. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  4. Study of virtual cathodes formation during beam-wave interaction in the reltron oscillator

    Science.gov (United States)

    Mahto, Manpuran; Jain, P. K.

    2017-09-01

    In the present work, a high power microwave oscillator—reltron has been analyzed to investigate the virtual cathode formation mechanism during the beam-wave interaction. In reltron, a side coupled modulation cavity is used as its RF interaction structure containing three metal grids along the longitudinal direction. The space charge current responsible for the virtual cathode and its steady state electric field distribution has been analyzed. Space charge and beam impedance conditions for efficient device operation have been demonstrated. It has been shown that during the beam-wave interaction in the device, first a virtual cathode forms in the post-acceleration gap, and then the second virtual cathode develops between the first and second grids of the modulation cavity. These two virtual cathodes co-exist and cause the formation of a third virtual cathode between the second and third grids. At this instant, only the third virtual cathode remains, and for sustained device oscillation, this process repeats periodically in the device. The present study would be useful in understanding the beam-wave interaction mechanism as well as the design and development of efficient reltron devices.

  5. Particle-In-Cell/Monte Carlo Simulation of Ion Back Bombardment in Photoinjectors

    International Nuclear Information System (INIS)

    Qiang, Ji; Corlett, John; Staples, John

    2009-01-01

    In this paper, we report on studies of ion back bombardment in high average current dc and rf photoinjectors using a particle-in-cell/Monte Carlo method. Using H 2 ion as an example, we observed that the ion density and energy deposition on the photocathode in rf guns are order of magnitude lower than that in a dc gun. A higher rf frequency helps mitigate the ion back bombardment of the cathode in rf guns

  6. Nanostructured lanthanum manganate composite cathode

    DEFF Research Database (Denmark)

    Wang, Wei Guo; Liu, Yi-Lin; Barfod, Rasmus

    2005-01-01

    that the (La1-xSrx)(y)MnO3 +/-delta (LSM) composite cathodes consist of a network of homogenously distributed LSM, yttria-stabilized zirconia (YSZ), and pores. The individual grain size of LSM or YSZ is approximately 100 nm. The degree of contact between cathode and electrolyte is 39% on average. (c) 2005...

  7. Gun Violence, Mental Illness, And Laws That Prohibit Gun Possession: Evidence From Two Florida Counties.

    Science.gov (United States)

    Swanson, Jeffrey W; Easter, Michele M; Robertson, Allison G; Swartz, Marvin S; Alanis-Hirsch, Kelly; Moseley, Daniel; Dion, Charles; Petrila, John

    2016-06-01

    Gun violence kills about ninety people every day in the United States, a toll measured in wasted and ruined lives and with an annual economic price tag exceeding $200 billion. Some policy makers suggest that reforming mental health care systems and improving point-of-purchase background checks to keep guns from mentally disturbed people will address the problem. Epidemiological research shows that serious mental illness contributes little to the risk of interpersonal violence but is a strong factor in suicide, which accounts for most firearm fatalities. Meanwhile, the effectiveness of gun restrictions focused on mental illness remains poorly understood. This article examines gun-related suicide and violent crime in people with serious mental illnesses, and whether legal restrictions on firearm sales to people with a history of mental health adjudication are effective in preventing gun violence. Among the study population in two large Florida counties, we found that 62 percent of violent gun crime arrests and 28 percent of gun suicides involved individuals not legally permitted to have a gun at the time. Suggested policy reforms include enacting risk-based gun removal laws and prohibiting guns from people involuntarily detained in short-term psychiatric hospitalizations. Project HOPE—The People-to-People Health Foundation, Inc.

  8. Gun Violence Following Inpatient Psychiatric Treatment: Offense Characteristics, Sources of Guns, and Number of Victims.

    Science.gov (United States)

    Kivisto, Aaron J

    2017-10-01

    This study presents data on the relative contribution to gun violence by people with a history of inpatient psychiatric treatment and on federal efforts to deter presumptively dangerous persons from obtaining firearms, information useful for analyzing the potential public health benefits of gun policies targeting people with serious mental illness. The study also estimates the reduction in gun violence victims that would be expected if individuals with a previous psychiatric hospitalization were prohibited from purchasing firearms. Data from 838 violent gun offenders from a nationally representative sample of state prison inmates were analyzed. Those with and without a history of psychiatric hospitalization were compared on a range of offense characteristics, including relationship to the victim, number of victims, location of the offense, and source of firearms. Inmates with a history of hospitalization constituted 12% of all violent gun offenders and accounted for 13% of the sample's victims. They were less likely than those without a previous hospitalization to victimize strangers (odds ratio=.52) and were no more likely to commit gun violence in public or to have multiple victims. Among those with previous hospitalizations, 78% obtained guns from sources not subject to federal background checks. Of the total 1,041 victims of gun violence, only 3% were victimized by participants with a history of hospitalization who obtained guns from currently regulated sources. Prohibiting all individuals with a history of psychiatric hospitalization from purchasing firearms, absent expanded background checks, was estimated to reduce the number of gun violence victims by only 3%.

  9. Gun Violence, Mental Illness, And Laws That Prohibit Gun Possession: Evidence From Two Florida Counties

    Science.gov (United States)

    Swanson, Jeffrey W.; Easter, Michele M.; Robertson, Allison G.; Swartz, Marvin S.; Alanis-Hirsch, Kelly; Moseley, Daniel; Dion, Charles; Petrila, John

    2016-01-01

    Gun violence kills about ninety people every day in the United States, a toll measured in wasted and ruined lives and with an annual economic price tag exceeding $200 billion. Some policy makers suggest that reforming mental health care systems and improving point-of-purchase background checks to keep guns from mentally disturbed people will address the problem. Epidemiological research shows that serious mental illness contributes little to the risk of interpersonal violence but is a strong factor in suicide, which accounts for most firearm fatalities. Meanwhile, the effectiveness of gun restrictions focused on mental illness remains poorly understood. This article examines gun-related suicide and violent crime in people with serious mental illnesses, and whether legal restrictions on firearm sales to people with a history of mental health adjudication are effective in preventing gun violence. Among the study population in two large Florida counties, we found that 62 percent of violent gun crime arrests and 28 percent of gun suicides involved individuals not legally permitted to have a gun at the time. Suggested policy reforms include enacting risk-based gun removal laws and prohibiting guns from people involuntarily detained in short-term psychiatric hospitalizations. PMID:27269024

  10. The supply and demand for guns to juveniles: Oakland's gun tracing project.

    Science.gov (United States)

    Calhoun, Deane; Dodge, Andrea Craig; Journel, Coraline S; Zahnd, Elaine

    2005-12-01

    In response to Oakland, California's high level of gun violence affecting young people, the East Oakland Partnership to Reduce Juvenile Gun Violence, a citywide collaboration, was formed in 1997. In 1999, the Partnership established the Oakland Gun Tracing Project to develop evidence-based policy recommendations aimed at reducing the supply of and demand for gun acquisition among urban youth. The advocacy project involved gathering, analyzing, and using police record and gun sale/registration data to inform policy and practice. Such data were collected for all gun crimes committed in Oakland, California between 1998 and 1999 in which a juvenile was either the suspect or the victim. The 213 cases involved 263 juveniles of which 170 were suspects/perpetrators and 93 were victims. Suspects as well as victims were predominantly male and African American. The 213 cases involved 132 recovered guns. Only 55% of the cases were traced to a federally licensed dealer. Three-quarters of the guns were purchased near Oakland, California. Successful traces, defined as the ability to identify federally licensed dealers and initial purchasers, were completed on only 52 of the 132 guns, demonstrating systemic tracing difficulties. Data gathered for the project was used to advocate for numerous policy changes. Recommended policy strategies include initiating a comprehensive gun tracing program so police can track all secondary sales, new laws requiring federal handgun registration which would track ownership changes, required reporting of stolen firearms, and providing effective intervention services to all juveniles the first time they enter the criminal justice system.

  11. SPS RF Cavity

    CERN Multimedia

    1975-01-01

    The picture shows one of the two initially installed cavities. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also gradually increased: by end 1980 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412017X, 7411048X, 7505074.

  12. SPS RF Accelerating Cavity

    CERN Multimedia

    1979-01-01

    This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X

  13. rf experiments on PLT

    International Nuclear Information System (INIS)

    Hosea, J.; Wilson, J.R.; Hooke, W.

    1986-01-01

    A variety of rf experiments are being conducted on PLT in order to explore rf techniques which could improve tokamak performance parameters. Of special importance are the studies of ion Bernstein wave (IBW) heating, lower hybrid MHD stabilization and electron heating, down-shifted electron cyclotron heating, and fast wave current drive. Ion Bernstein wave heating results at modest power indicate that the particle confinement time could be enhanced relative to that for fast wave heating in the ion cyclotron range of frequencies (ICRF) and neutral beam heating. At these power levels a conclusive determination of energy confinement scaling with power cannot yet be given. Central sawtooth and m = 1 MHD stabilization is being obtained with centrally peaked lower hybrid (LH) current drive and the central electron temperature is peaking to values (approx.5 keV) well outside the bounds of ''profile consistency.'' In this case the electron energy confinement is apparently increased relative to the ohmic value. The production of relativistic electrons via heating at the down-shifted electron cyclotron (EC) frequency is found to be consistent with theoretical predictions and lends support to the use of this method for heating in relatively high magnetic field devices

  14. Fabrication of compact electron gun for 6 MeV X-ray source

    International Nuclear Information System (INIS)

    Ghodke, S.R.; Barnwal, Rajesh; Kumar, Mahendra

    2014-01-01

    The 6 MeV X-Ray source for container cargo scanning application has been designed and developed by the Accelerator and Pulse Power Division, BARC, Mumbai. This compact linac has been designed as a mobile system, to be mounted on a moving container. In linac-based cargo-scanning system, to work electron gun on a movable container, it has to be robust. Electron gun is to work at 10 -7 mbar vacuum and 2000 degree Celsius temperature. An effort is made to engineer the gun assembly to make it more robust and aligned. The linac acts as the source of X-rays, which fall on the cargo and are then detected by the detector system. Many components are indigenously developed like grid, insulating ring, Tungsten filament and filament guide, which are made from alumina ceramic and Tantalum which is to work at 1500 degree Celsius. Filament connector is made from Invar to reduce heat loss and to make rigid connection. It was CNC machined and wire cut by EDM. Invar and Copper electrode feed through is shrink fitted with the help of liquid Nitrogen. Shrink fit tolerances of 15 micrometer are achieved by jig boring machining processes. Tantalum cup for LaB6 cathode and heat shield are made from die and punch mechanism. For alignment of electron emitter with beam axis this Tantalum cup is a crucial component. Electron gun is assembled and aligned its components with the help of precision jigs. The whole assembly was Helium leak tested by MSLD up to 4 x 10 -10 mbar.l/s vacuum, no leak was found. This paper will describe the machining, Tantalum cup forming, ceramic components development, heat shields, ceramic feed through etc of electron gun. (author)

  15. Gun Violence, mental health, and Connecticut physicians.

    Science.gov (United States)

    Dodds, Peter R; Anderson, Caitlyn O; Dodds, Jon H

    2014-01-01

    While there is a public perception that gun violence is associated with mental illness we present evidence that it is a complex public health problem which defies simple characterizations and solutions. Only a small percentage of individuals with mental illness are at risk for extreme violence and they account for only a small percentage of gun-related homicides. Individuals who are at risk for gun violence are difficult to identify and successfully treat. The incidence, and perhaps the demographics, of gun violence vary substantially from state to state. We make a case for Connecticut physicians to study gun violence at the state level. We recommend that Connecticut physicians promote and expand upon the American Academy of Pediatrics' recommendation for creating a "safe home environment. "We suggest that guns be secured in all homes in which there are children. In addition we suggest that guns be voluntarily removed from homes in which there are individuals with a history of violence, threats of violence, depression, drug and/or alcohol abuse, and individuals with major mental illnesses who are not cooperating with therapy.

  16. Simple light gas guns for hypervelocity studies

    International Nuclear Information System (INIS)

    Combs, S.K.; Haselton, H.H.; Milora, S.L.

    1990-01-01

    Two-stage light guns are used extensively in hypervelocity research. The applications of this technology include impact studies and special materials development. Oak Ridge National Laboratory (ORNL) has developed two-stage guns that accelerate small projectiles (4-mm nominal diameter) to velocities of up to ∼5 km/s. These guns are relatively small and simple (thus, easy to operate), allowing a significant number of test shots to be carried out and data accumulated in a short time. Materials that have been used for projectiles include plastics, frozen isotopes of hydrogen, and lithium hydride. One gun has been used to demonstrate repetitive operation at a rate of 0.7 Hz; and, with a few design improvements, it appears capable of performing at firing frequencies of 1--2 Hz. A schematic of ORNL two-stage device is shown below. Unlike most such devices, no rupture disks are used. Instead, a fast valve (high-flow type) initiates the acceleration process in the first stage. Projectiles can be loaded into the gun breech via the slide mechanism; this action has been automated which allows repetitive firing. Alternatively, the device is equipped with ''pipe gun'' apparatus in which gas can be frozen in situ in the gun barrel to form the projectile. This equipment operates with high reliability and is well suited for small-scale testing at high velocity. 17 refs., 6 figs., 2 tabs

  17. Ready, Fire, Aim: The College Campus Gun Fight

    Science.gov (United States)

    Birnbaum, Robert

    2013-01-01

    The question of whether guns should be permitted on college and university campuses in the United States reflects the tension between two competing perspectives. America has both a robust gun culture and an equally robust (if less well known) gun-control culture. The gun culture is as American as apple pie: There may be as many as 300 million…

  18. Gun Safety Management with Patients at Risk for Suicide

    Science.gov (United States)

    Simon, Robert I.

    2007-01-01

    Guns in the home are associated with a five-fold increase in suicide. All patients at risk for suicide must be asked if guns are available at home or easily accessible elsewhere, or if they have intent to buy or purchase a gun. Gun safety management requires a collaborative team approach including the clinician, patient, and designated person…

  19. Correlates of Gun Involvement and Aggressiveness among Adolescents.

    Science.gov (United States)

    Ding, Cody S.; Nelsen, Edward A.; Lassonde, Cynthia T.

    2002-01-01

    Investigated adolescents' aggressiveness in relation to their experiences, beliefs, and attitudes concerning gun use, also noting family composition, relationships with parents, and emotionality as correlates of gun involvement and aggression. Student surveys indicated links between gun ownership and recreational use, beliefs about gun use, and…

  20. Gun ownership and firearm-related deaths.

    Science.gov (United States)

    Bangalore, Sripal; Messerli, Franz H

    2013-10-01

    A variety of claims about possible associations between gun ownership rates, mental illness burden, and the risk of firearm-related deaths have been put forward. However, systematic data on this issue among various countries remain scant. Our objective was to assess whether the popular notion "guns make a nation safer" has any merits. Data on gun ownership were obtained from the Small Arms Survey, and for firearm-related deaths from a European detailed mortality database (World Health Organization), the National Center for Health Statistics, and others. Crime rate was used as an indicator of safety of the nation and was obtained from the United Nations Surveys of Crime Trends. Age-standardized disability-adjusted life-year rates due to major depressive disorder per 100,000 inhabitants with data obtained from the World Health Organization database were used as a putative indicator for mental illness burden in a given country. Among the 27 developed countries, there was a significant positive correlation between guns per capita per country and the rate of firearm-related deaths (r = 0.80; P guns per capita per country and crime rate (r = .33), or between mental illness and crime rate (r = 0.32; P = .11). In a linear regression model with firearm-related deaths as the dependent variable with gun ownership and mental illness as independent covariates, gun ownership was a significant predictor (P guns per capita per country was a strong and independent predictor of firearm-related death in a given country, whereas the predictive power of the mental illness burden was of borderline significance in a multivariable model. Regardless of exact cause and effect, however, the current study debunks the widely quoted hypothesis that guns make a nation safer. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Alpha Fuels Environmental Test Facility impact gun

    International Nuclear Information System (INIS)

    Anderson, C.G.

    1978-01-01

    The Alpha Fuels Environmental Test Facility (AFETF) impact gun is a unique tool for impact testing 238 PuO 2 -fueled heat sources of up to 178-mm dia at velocities to 300 m/s. An environmentally-sealed vacuum chamber at the muzzle of the gun allows preheating of the projectile to 1,000 0 C. Immediately prior to impact, the heat source projectile is completely sealed in a vacuum-tight catching container to prevent escape of its radioactive contents should rupture occur. The impact velocity delivered by this gas-powered gun can be regulated to within +-2%

  2. Evaluation of Smart Gun Technologies preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, D.R.

    1996-01-01

    The Smart Gun Technology Project has a goal to eliminate the capability of an unauthorized user from firing a law enforcement officer`s firearm by implementing {open_quote}smart{close_quote} technologies. Smart technologies are those that can in some manner identify an officer. This report will identify, describe, and grade various technologies as compared to the requirements that were obtained from officers. This report does not make a final recommendation for a smart gun technology, nor does it give the complete design of a smart gun system.

  3. "Is there a gun in the home?" Assessing the risks of gun ownership in older adults.

    Science.gov (United States)

    Pinholt, Ellen M; Mitchell, Joshua D; Butler, Jane H; Kumar, Harjinder

    2014-06-01

    An important ethical and safety concern that geriatricians, primary care providers, and home health professionals need to address is gun ownership by elderly adults. Those aged 65 and older now have the highest rate of gun ownership in America, and they also have a high prevalence of depression and suicide. Dementia can add additional layers of risk. Even older gun owners who are otherwise intellectually intact may benefit from information about gun safety with the increasing numbers of children being cared for by grandparents. Health professionals should ask patients, "Is there a gun in the home?" in the clinic and during home visits. Healthcare professionals must have knowledge and skills to address safe gun ownership in elderly adults. The 5 L's (Locked, Loaded, Little children, feeling Low, Learned owner) will assist professionals in addressing all aspects of safe ownership. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.

  4. Camouflaged Collectives: Managing Stigma and Identity at Gun Events

    Directory of Open Access Journals (Sweden)

    Sarah Jane Blithe

    2017-02-01

    Full Text Available Gun violence persists in the United States, claiming lives and escalating healthcare costs. This article seeks to contribute to social justice work on the “gun problem” by studying gun collectives. To understand gun culture and to identify gun violence reduction strategies, we study places where gun owners organize – legal (and sometimes illegal settings that facilitate dialogue about gun issues. Based on participant observation and collaborative event ethnography at gun shows and a private shooting party, this analysis presents findings about the practices gun collective members use to manage stigma. We conclude that when participants in gun events attempt to subvert core stigma through everyday stigma management practices, they effectively facilitate the unfettered exchange of potentially dangerous goods, promote the invisibility of oppressive structures, and normalize violence.

  5. Exact cancellation of emittance growth due to coupled transverse dynamics in solenoids and rf couplers

    Science.gov (United States)

    Dowell, David H.; Zhou, Feng; Schmerge, John

    2018-01-01

    Weak, rotated magnetic and radio frequency quadrupole fields in electron guns and injectors can couple the beam's horizontal with vertical motion, introduce correlations between otherwise orthogonal transverse momenta, and reduce the beam brightness. This paper discusses two important sources of coupled transverse dynamics common to most electron injectors. The first is quadrupole focusing followed by beam rotation in a solenoid, and the second coupling comes from a skewed high-power rf coupler or cavity port which has a rotated rf quadrupole field. It is shown that a dc quadrupole field can correct for both types of couplings and exactly cancel their emittance growths. The degree of cancellation of the rf skew quadrupole emittance is limited by the electron bunch length. Analytic expressions are derived and compared with emittance simulations and measurements.

  6. RF breakdown by toroidal helicons

    Indian Academy of Sciences (India)

    Abstract. Bounded whistlers are well-known for their efficient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohy- drodynamic (EMHD) frequency ...

  7. RF breakdown by toroidal helicons

    Indian Academy of Sciences (India)

    Bounded whistlers are well-known for their efficient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohydrodynamic (EMHD) frequency regime is fed to ...

  8. Rail gun powered by an integral explosive generator

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, D.R.; Fowler, C.M.

    1979-01-01

    We propose the use of a rail gun powered by an explosive magnetic flux compression generator built into the rail gun itself in which the rails of the gun are driven together behind the projectile by explosives. The magnetic field established between the rails by an initial current supplied by an external source at the breech of the gun is trapped and compressed by the collapsing rails to accelerate the projectile down the bore of the gun.

  9. Rail gun powered by an integral explosive generator

    International Nuclear Information System (INIS)

    Peterson, D.R.; Fowler, C.M.

    1979-01-01

    We propose the use of a rail gun powered by an explosive magnetic flux compression generator built into the rail gun itself in which the rails of the gun are driven together behind the projectile by explosives. The magnetic field established between the rails by an initial current supplied by an external source at the breech of the gun is trapped and compressed by the collapsing rails to accelerate the projectile down the bore of the gun

  10. Refurbishments of RF systems

    International Nuclear Information System (INIS)

    Baelde, J.L.

    1998-01-01

    This document describes the activities of the R.F. System group during the years 1995-1996 in the frame of the refurbishment of the control system at GANIL accelerator. Modifications concerning the following sub-assemblies are mentioned: 1. voltage standards; 2. link card between the step by step motor control and the local control systems; 3. polarization system; 4. computer software for different operations. Also reported is the installation of ECR 4 source for the CO2. In this period the R2 Regrouping system has been installed, tested and put into operation. Several problems concerning the mechanical installation of the coupling loop and other problems related to the electronics operation were solved. The results obtained with the THI machine are presented

  11. Beam induced RF heating

    CERN Document Server

    Salvant, B; Arduini, G; Assmann, R; Baglin, V; Barnes, M J; Bartmann, W; Baudrenghien, P; Berrig, O; Bracco, C; Bravin, E; Bregliozzi, G; Bruce, R; Bertarelli, A; Carra, F; Cattenoz, G; Caspers, F; Claudet, S; Day, H; Garlasche, M; Gentini, L; Goddard, B; Grudiev, A; Henrist, B; Jones, R; Kononenko, O; Lanza, G; Lari, L; Mastoridis, T; Mertens, V; Métral, E; Mounet, N; Muller, J E; Nosych, A A; Nougaret, J L; Persichelli, S; Piguiet, A M; Redaelli, S; Roncarolo, F; Rumolo, G; Salvachua, B; Sapinski, M; Schmidt, R; Shaposhnikova, E; Tavian, L; Timmins, M; Uythoven, J; Vidal, A; Wenninger, J; Wollmann, D; Zerlauth, M

    2012-01-01

    After the 2011 run, actions were put in place during the 2011/2012 winter stop to limit beam induced radio frequency (RF) heating of LHC components. However, some components could not be changed during this short stop and continued to represent a limitation throughout 2012. In addition, the stored beam intensity increased in 2012 and the temperature of certain components became critical. In this contribution, the beam induced heating limitations for 2012 and the expected beam induced heating limitations for the restart after the Long Shutdown 1 (LS1) will be compiled. The expected consequences of running with 25 ns or 50 ns bunch spacing will be detailed, as well as the consequences of running with shorter bunch length. Finally, actions on hardware or beam parameters to monitor and mitigate the impact of beam induced heating to LHC operation after LS1 will be discussed.

  12. Gun- and Non-Gun-Related Violence Exposure and Risk for Subsequent Gun Carrying Among Male Juvenile Offenders.

    Science.gov (United States)

    Beardslee, Jordan; Mulvey, Edward; Schubert, Carol; Allison, Paul; Infante, Arynn; Pardini, Dustin

    2018-04-01

    Although studies have found that youth exposed to violence are more likely to carry guns than non-exposed youth, this association could be due to common causal factors or other pre-existing differences between individuals. In this study, within-individual change models were used to determine whether juvenile offenders exhibit an increased propensity to carry a firearm after being exposed to gun violence and/or non-gun violence. The advantage of this approach is all time-invariant factors are eliminated as potential confounders. A sample of 1,170 racially/ethnically diverse male juvenile offenders was recruited in Arizona and Pennsylvania (14-19 years old at recruitment). Participants were interviewed every 6 months for 3 years followed by 4 annual assessments. The outcome was gun carrying and the primary predictors were exposure to gun violence and non-gun violence. Time-varying covariates included exposure to peers who carried guns, exposure to peers who engaged in other (non-gun) criminal acts, developmental changes in gun carrying, and changes in gun carrying from incarceration or institutionalization. Adolescent offenders were significantly more likely to carry a gun in recall periods after exposure to gun violence, but not after exposure to non-gun violence. Effect of gun violence on carrying was significant throughout adolescence and young adulthood and could not be accounted for by time-varying and time-invariant confounders. Interventions to decrease illegal gun carrying should target young men in medical and mental health settings who experience or witness gun violence and those living in communities with high rates of gun violence. Copyright © 2018 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

  13. Magnetron priming by multiple cathodes

    Science.gov (United States)

    Jones, M. C.; Neculaes, V. B.; Lau, Y. Y.; Gilgenbach, R. M.; White, W. M.; Hoff, B. W.; Jordan, N. M.

    2005-08-01

    A relativistic magnetron priming technique using multiple cathodes is simulated with a three-dimensional, fully electromagnetic, particle-in-cell code. This technique is based on electron emission from N /2 individual cathodes in an N-cavity magnetron to prime the π mode. In the case of the six-cavity relativistic magnetron, π-mode start-oscillation times are reduced up to a factor of 4, and mode competition is suppressed. Most significantly, the highest microwave field power is observed by utilizing three cathodes compared to other recently explored priming techniques.

  14. Uudised : Guns N' Roses Soomes. Valmis ulmeraadio

    Index Scriptorium Estoniae

    2006-01-01

    Ameerika hard-rock-bändi Guns N' Roses kontserdist 5. juulil Hartwall Areenal Soomes. Kord kuus on Ulmeplaatide kodulehekülel www. ulmeplaadid.ee võimalus kuulata ulmeraadiot, kus esitusel eesti kergemuusika

  15. Mass Shootings, Mental Illness, and Gun Control.

    Science.gov (United States)

    Philpott-Jones, Sean

    2018-03-01

    In the wake of the Stoneman Douglas School shooting, Republican and Democratic leaders-like the American electorate they represent-remain sharply divided in their responses to gun violence. They are united in their condemnation of these mass shootings, but they disagree about whether stricter or looser gun control laws are the answer. Those on the right side of the political aisle suggest that the issue is one of mental illness rather than gun control. Conversely, those who are more liberal or progressive in their political learnings are quick to condemn attempts to reframe the issue of mass shootings as a mental health problem. Both sides are wrong. Mass shootings are indeed partially a mental health problem, albeit one poorly addressed by our current laws and policies. But the solution to mass shootings also needs to consider strategies that may reduce gun violence in general. © 2018 The Hastings Center.

  16. Ballistic Rail Gun Soft Recovery Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Ballistic Rail Gun Soft Recovery Facility accommodates a 155mm Howitzer, fired horizontally into a 104-foot long water trough to slow the projectile and recover...

  17. Sonic Rarefaction Wave Low Recoil Gun

    National Research Council Canada - National Science Library

    Kathe, E

    2002-01-01

    .... The sonic RArefaction waVE low recoil guN (RAVEN) is a novel invention to dramatically reduce the gas momentum contribution to recoil with absolutely no reduction in me ballistic efficiency of launch...

  18. Prestressed Carbon Fiber Composite Overwrapped Gun Tube

    National Research Council Canada - National Science Library

    Littlefield, Andrew; Hyland, Edward

    2006-01-01

    .... Using composite materials not only directly removes weight from the gun tube but, by better balancing the tube, allows the use of smaller drive systems, thus further enhancing the system weight loss...

  19. Cost Estimate for Gun Liner Emplacement

    Science.gov (United States)

    2011-08-01

    the gun tube. (The Rowan cost estimate includes the extra thermal soak for the explosive bonding process.) The cost for the extra stress relief... nuts for optimum performance. GUIDANCE SYSTEM:  Cylinder guidance is provide by the rod bushing

  20. Ion Back-Bombardment of GaAs Photocathodes Inside DC High Voltage Electron Guns

    CERN Document Server

    Grames, Joseph M; Brittian, Joshua; Charles, Daniel; Clark, Jim; Hansknecht, John; Lynn Stutzman, Marcy; Poelker, Matthew; Surles-Law, Kenneth E

    2005-01-01

    The primary limitation for sustained high quantum efficiency operation of GaAs photocathodes inside DC high voltage electron guns is ion back-bombardment of the photocathode. This process results from ionization of residual gas within the cathode/anode gap by the extracted electron beam, which is subsequently accelerated backwards to the photocathode. The damage mechanism is believed to be either destruction of the negative electron affinity condition at the surface of the photocathode or damage to the crystal structure by implantation of the bombarding ions. This work characterizes ion formation within the anode/cathode gap for gas species typical of UHV vacuum chambers (i.e., hydrogen, carbon monoxide and methane). Calculations and simulations are performed to determine the ion trajectories and stopping distance within the photocathode material. The results of the simulations are compared with test results obtained using a 100 keV DC high voltage GaAs photoemission gun and beamline at currents up to 10 mA D...

  1. Performance of a DC GaAs photocathode gun for the Jefferson lab FEL

    CERN Document Server

    Siggins, T; Bohn, C L; Bullard, D; Douglas, D; Grippo, A; Gubeli, J; Krafft, G A; Yunn, B

    2001-01-01

    The performance of the 320 kV DC photocathode gun has met the design specifications for the 1 kW IR Demo FEL at Jefferson Lab. This gun has shown the ability to deliver high average current beam with outstanding lifetimes. The GaAs photocathode has delivered 135 pC per bunch, at a bunch repetition rate of 37.425 MHz, corresponding to 5 mA average CW current. In a recent cathode lifetime measurement, 20 h of CW beam was delivered with an average current of 3.1 mA and 211 C of total charge from a 0.283 cm sup 2 illuminated spot. The cathode showed a 1/e lifetime of 58 h and a 1/e extracted charge lifetime of 618 C. We have achieved quantum efficiencies of 5% from a GaAs wafer that has been in service for 13 months delivering in excess 2400 C with only three activation cycles.

  2. A Micromechanical RF Channelizer

    Science.gov (United States)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  3. The Impact of Banning Juvenile Gun Possession.

    OpenAIRE

    Marvell, Thomas B

    2001-01-01

    A 1994 federal law bans possession of handguns by persons under 18 years of age. Also in 1994, 11 states passed their own juvenile gun possession bans. Eighteen states had previously passed bans, 15 of them between 1975 and 1993. These laws were intended to reduce homicides, but arguments can be made that they have no effect on or that they even increase the homicide rate. This paper estimates the laws' impacts on various crime measures, primarily juvenile gun homicide victimizations and suic...

  4. Electrothermal plasma gun as a pellet injector

    International Nuclear Information System (INIS)

    Kincaid, R.W.; Bourham, M.A.

    1994-01-01

    The NCSU electrothermal plasma gun SIRENS has been used to accelerate plastic (Lexan polycarbonate) pellets, to determine the feasibility of the use of electrothermal guns as pellet injectors. The use of an electrothermal gun to inject frozen hydrogenic pellets requires a mechanism to provide protective shells (sabots) for shielding the pellet from ablation during acceleration into and through the barrel of the gun. The gun has been modified to accommodate acceleration of the plastic pellets using special acceleration barrels equipped with diagnostics for velocity and position of the pellet, and targets to absorb the pellet's energy on impact. The length of the acceleration path could be varied between 15 and 45 cm. The discharge energy of the electrothermal gun ranged from 2 to 6 kJ. The pellet velocities have been measured via a set of break wires. Pellet masses were varied between 0.5 and 1.0 grams. Preliminary results on 0.5 and 1.0 g pellets show that the exit velocity reaches 0.9 km/s at 6 kJ input energy to the source. Higher velocities of 1.5 and 2.7 km/s have been achieved using 0.5 and 1.0 gm pellets in 30 cm long barrel, without cleaning the barrel between the shots

  5. Are "goods for guns" good for the community? An update of a community gun buyback program.

    Science.gov (United States)

    Green, Jonathan; Damle, Rachelle N; Kasper, Rebecca E; Violano, Pina; Manno, Mariann; Nazarey, Pradeep P; Aidlen, Jeremy T; Hirsh, Michael P

    2017-08-01

    Gun violence remains a leading cause of death in the United States. Community gun buyback programs provide an opportunity to dispose of extraneous firearms. The purpose of this study was to understand the demographics, motivation, child access to firearms, and household mental illness of buyback participants in hopes of improving the program's effectiveness. A 2015 Injury Free Coalition for Kids gun buyback program which collaborated with local police departments was studied. We administered a 23-item questionnaire survey to gun buyback participants assessing demographic characteristics, motivation for relinquishing firearms, child firearm accessibility, and mental illness/domestic violence history. A total of 186 individuals from Central/Western Massachusetts turned in 339 weapons. Participants received between US $25 and US $75 in gift cards dependent on what type of gun was turned in, with an average cost of $41/gun. A total of 109 (59%) participants completed the survey. Respondents were mostly white (99%), men (90%) and first-time participants in the program (85.2%). Among survey respondents, 54% turned in firearms "for safety reasons." Respondents reported no longer needing/wanting their weapons (47%) and approximately one in eight participants were concerned the firearm(s) were accessible to children. Most respondents (87%) felt the program encouraged neighborhood awareness of firearm safety. Three of every five participants reported that guns still remained in their homes; additionally, 21% where children could potentially access them and 14% with a history of mental illness/suicide/domestic violence in the home. Gun buybacks can provide a low-cost means of removing unwanted firearms from the community. Most participants felt their homes were safer after turning in the firearm(s). In homes still possessing guns, emphasis on secure gun storage should continue, increasing the safety of children and families. The results of this survey also provided new

  6. The AGS Booster high frequency rf system

    International Nuclear Information System (INIS)

    Sanders, R.T.; Cameron, P.; Eng, W.; Goldman, M.A.; Jablonski, E.; Kasha, D.; Keane, J.; McNerney, A.; Meth, M.; Plotkin, M.; Puglisi, M.; Ratti, A.; Spitz, R.

    1991-01-01

    A high level rf system, including a power amplifier and cavity, has been designed and built for the AGS Booster. It covers a frequency range of 2.4 to 4.2 MHz and will be used to accelerate high intensity protons. Low intensity polarized protons and heavy ions, to the 1.5 GeV level. A total accelerating voltage of up to 90 kV will be provided by two cavities, each having two gaps. The internally cross coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate beam intensities up to 0.75 x 10 13 protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two parallel cells. The amplifier is a grounded cathode configuration driven by a remotely located solid-state amplifier. It has been tested in the laboratory at full gap voltage with satisfactory results. 5 refs., 2 figs., 1 tab

  7. The AGS Booster high frequency RF system

    International Nuclear Information System (INIS)

    Sanders, R.T.; Cameron, P.; Eng, W.; Goldman, M.A.; Jablonski, E.; Kasha, D.; Keane, J.; McNerney, A.; Meth, M.; Plotkin, M.; Puglisi, M.; Ratti, A.; Spitz, R.

    1991-01-01

    A high level RF system, including a power amplifier and cavity, has been designed and built for the AGS Booster. It covers a frequency range of 2.4 to 4.2 MHz and will be used to accelerate high intensity protons, low intensity polarized protons and heavy ions, to the 1.5 GeV level. A total accelerating voltage of up to 90 kV will be provided by two cavities, each having two gaps. The internally cross-coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate beam intensities up to 0.75 x 10 13 protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two parallel cells. The amplifier is a grounded cathode configuration driven by a remotely located solid-state amplifier. It has been tested in the laboratory at full gap voltage with satisfactory results

  8. Separating Batterers and Guns: A Review and Analysis of Gun Removal Laws in 50 States

    Science.gov (United States)

    Frattaroli, Shannon; Vernick, Jon S.

    2006-01-01

    Firearms play an important role in lethal domestic violence incidents. The authors review state laws regarding two policies to separate batterers from firearms: laws authorizing police to remove firearms when responding to a domestic violence complaint ("police gun removal laws") and laws authorizing courts to order guns removed from batterers…

  9. Relationship between licensing, registration, and other gun sales laws and the source state of crime guns.

    Science.gov (United States)

    Webster, D W; Vernick, J S; Hepburn, L M

    2001-09-01

    To determine the association between licensing and registration of firearm sales and an indicator of gun availability to criminals. Tracing data on all crime guns recovered in 25 cities in the United States were used to estimate the relationship between state gun law categories and the proportion of crime guns first sold by in-state gun dealers. In cities located in states with both mandatory registration and licensing systems (five cities), a mean of 33.7% of crime guns were first sold by in-state gun dealers, compared with 72.7% in cities that had either registration or licensing but not both (seven cities), and 84.2% in cities without registration or licensing (13 cites). Little of the difference between cities with both licensing and registration and cities with neither licensing nor registration was explained by potential confounders. The share of the population near a city that resides in a neighboring state without licensing or registration laws was negatively associated with the outcome. States with registration and licensing systems appear to do a better job than other states of keeping guns initially sold within the state from being recovered in crimes. Proximity to states without these laws, however, may limit their impact.

  10. Gun Carrying by High School Students in Boston, MA: Does Overestimation of Peer Gun Carrying Matter?

    Science.gov (United States)

    Hemenway, David; Vriniotis, Mary; Johnson, Renee M.; Miller, Matthew; Azrael, Deborah

    2011-01-01

    This paper investigates: (1) whether high school students overestimate gun carrying by their peers, and (2) whether those students who overestimate peer gun carrying are more likely to carry firearms. Data come from a randomly sampled survey conducted in 2008 of over 1700 high school students in Boston, MA. Over 5% of students reported carrying a…

  11. Gun suicide by young people in California: descriptive epidemiology and gun ownership.

    Science.gov (United States)

    Wright, Mona A; Wintemute, Garen J; Claire, Barbara E

    2008-12-01

    We studied the 336 firearm suicides occurring in California in 1997-1999 to persons under age 21. The gun used was most often owned by the victim or a family member living in the victim's household. Prevention efforts should focus on gun ownership and accessibility.

  12. The hired gun expert witness.

    Science.gov (United States)

    Beck, M

    1994-04-01

    This article briefly discusses the role of the expert physician witness at trial and describes what is emerging as the physician professional witness (AKA hired gun). The trial court's powers to evaluate the professionalism and objectivity of an expert witness are examined in light of a recent Western District Missouri Court of Appeals case. This case, while limited to its peculiar set of facts, permitted both a hearing and production of documents of a physician who had been hired to testify. This article reviews the role of the expert physician witness in Missouri litigation in light of recent caselaw outlining discovery procedures to monitor use of professional witnesses. The term "professional witness" does not refer to witnesses who are professionals, but rather to persons who make their entire living witnessing. The Missouri Court of Appeals ruling in State ex rel. Lichtor v. Clark, 845 S.W.2d (Mo.App. W.D. 1992) elucidates the Missouri Courts' authority in sorting out unprofessional physicians who would offer unobjective expert testimony. While this particular article is intended for medical readership and discusses expert physician witnesses, expert witnesses can come from any profession including engineering, accounting, nursing, etc. It might thus be assumed that the Lichtor Court's procedure may be applied to any expert whose objectivity has been put into question.

  13. Modeling internal ballistics of gas combustion guns.

    Science.gov (United States)

    Schorge, Volker; Grossjohann, Rico; Schönekess, Holger C; Herbst, Jörg; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

    2016-05-01

    Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur.

  14. Characterization of an SRF gun: a 3D full wave simulation

    International Nuclear Information System (INIS)

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

    2011-01-01

    We characterized a BNL 1.3GHz half-cell SRF gun is tested for GaAs photocathode. The gun already was simulated several years ago via two-dimensional (2D) numerical codes (i.e., Superfish and Parmela) with and without the beam. In this paper, we discuss our investigation of its characteristics using a three dimensional (3D) full-wave code (CST STUDIO SUITE(trademark)).The input/pickup couplers are sited symmetrically on the same side of the gun at an angle of 180 o . In particular, the inner conductor of the pickup coupler is considerably shorter than that of the input coupler. We evaluated the cross-talk between the beam (trajectory) and the signal on the input coupler compared our findings with published results based on analytical models. The CST STUDIO SUITE(trademark) also was used to predict the field within the cavity; particularly, a combination of transient/eigenmode solvers was employed to accurately construct the RF field for the particles, which also includes the effects of the couplers. Finally, we explored the beam's dynamics with a particle in cell (PIC) simulation, validated the results and compare them with 2D code result.

  15. Application of Ferroelectric Cathodes to Enhance the Ion Yield in the Caesar Source at LNS

    CERN Document Server

    Boscolo, I; Cialdi, S; Ciavola, G; Cipriani, D; Gammino, S; Handerek, J; Marletta, S; Riege, H; Somarè, G; Valentini, M

    2000-01-01

    With increasing RF power the electron concentration in the plasma of ECR ion sources is decreasing in comparison to the ion concentration, so that the plasma is charging up positively. Direct injection of electrons into the ECR plasma can increase the electron charge density and the ion current yield. We have used ferroelectric cathodes to inject electrons into the Argon plasma of the CAESAR ion source at INFN-LNS (Catania, Italy). The cathode was placed at about 10 cm from the hot plasma and a bipolar high voltage pulse of 1.6 kV was used to trigger the electron emission. No additional acceleration has been provided. The use of the ferroelectric cathode leads to an increase of about 30% of the Ar8+ intensity, which has been monitored during the test. In addition, magneto-hydrodynamic instabilities in the ECR source were damped during and after electron injection.

  16. Design and simulation of 3½-cell superconducting gun cavity and beam dynamics studies of the SASE-FEL System at the Institute of Accelerator Technologies at Ankara University

    International Nuclear Information System (INIS)

    Yildiz, H. Duran; Cakir, R.; Porsuk, D.

    2015-01-01

    Design and simulation of a superconducting gun cavity with 3½ cells have been studied in order to give the first push to the electron beam for the linear accelerating system at The Institute of Accelerator Technologies at Ankara University. Electrons are accelerated through the gun cavity with the help of the Radiofrequency power suppliers from cryogenic systems. Accelerating gradient should be as high as possible to accelerate electron beam inside the cavity. In this study, electron beam reaches to 9.17 MeV energy at the end of the gun cavity with the accelerating gradient; E c =19.21 MV/m. 1.3 GHz gun cavity consists of three TESLA-like shaped cells while the special designed gun-cell includes a cathode plug. Optimized important beam parameters inside the gun cavity, average beam current 3 mA, transverse emittance 2.5 mm mrad, repetition rate 30 MHz and other parameters are obtained for the SASE-FEL System. The Superfish/Poisson program is used to design each cell of the superconducting cavity. Superconducting gun cavity and Radiofrequency properties are studied by utilizing 2D Superfish/Poisson, 3D Computer Simulation Technology Microwave Studio, and 3D Computer Simulation Technology Particle Studio. Superfish/Poisson is also used to optimize the geometry of the cavity cells to get the highest accelerating gradient. The behavior of the particles along the beamline is included in this study. ASTRA Code is used to track the particles

  17. Measurements of the Argonne Wakefield Accelerator's low charge, 4 MeV RF photocathode witness beam

    International Nuclear Information System (INIS)

    Power, J.

    1998-01-01

    The Argonne Wakefield Accelerator's (AWA) witness RF photocathode gun produced its first electron beam in April of 1996. We have characterized the charge, energy, emittance and bunch length of the witness beam over the last several months. The emittance Was measured by both a quad scan that fitted for space charge using an in house developed Mathematica routine and a pepper pot technique. The bunch length was measured by imaging Cherenkov light from a quartz plate to a Hamamatsu streak camera with 2 psec resolution. A beam energy of 3.9 Mev was measured with a 6 inch round pole spectrometer while a beam charge was measured with both an ICT and a Faraday Cup. Although the gun will normally be run at 100 pC it has produced charges from 10 pC to 4 nc. All results of the measurements to date are presented here

  18. To Your Health: NLM update transcript - Gun safety strategies

    Science.gov (United States)

    ... transcript040918.html To Your Health: NLM update Transcript Gun safety strategies : 04/09/2018 To use the ... on weekly topics. An evidence-based, public health gun safety strategy that is consistent with second amendment ...

  19. Tri-Service Green Gun Barrel (PP 1074)

    National Research Council Canada - National Science Library

    Rusch, Lawrence F

    2003-01-01

    ...) PP 1074 Tri-Service Green Gun Barrel. The program's goal was to develop an environmentally friendly process for depositing wear and erosion resistant materials onto gun bores replacing the current hazardous aqueous electro-deposition...

  20. Simple gun for vapor deposition of organic thin films

    International Nuclear Information System (INIS)

    Sato, N.; Seki, K.; Inokuchi, H.

    1987-01-01

    A simple evaporation gun for preparing organic thin films was fabricated using commercially available parts of an electron gun for a TV Braun tube. The device permits sample heating to be easily controlled because of the small heat capacity

  1. Pulser for the Tevatron electron lens gun

    Energy Technology Data Exchange (ETDEWEB)

    Iouri Terechkine et al.

    2004-05-18

    To compensate for beam-beam interaction in Tevatron, an ''electron lens'' is considered to be an effective instrument. When a bunch of electrons with energy in the range (10-16) kV is overlapping with a bunch of antiprotons, the resulting focusing force for antiprotons can be adjusted by changing the electron beam current and by profiling its radial distribution. There exist several scenarios of how the system must function. According to one of them, an electron gun that supplies electrons must be fed by voltage pulses that follow with the frequency of antiproton bunches circulating in the Tevatron, which is about 2.5 MHz. To provide focusing tailored for each individual antiproton bunch, a modulator of the gun (pulser) must allow pulse-to-pulse voltage change. This report will cover main approaches to a design of a pulser for use with the gun of the Tevatron Electron Lens.

  2. Activation Layer Stabilization of High Polarization Photocathodes in Sub-Optimal RF Gun Environments

    Energy Technology Data Exchange (ETDEWEB)

    Mulhollan, Gregory; /SLAC /Saxed Surface Science, Austin, TX

    2010-08-25

    We have developed an activation procedure by which the reactivity to CO{sub 2}, a principal cause of yield decay for GaAs photocathodes, is greatly reduced. The use of a second alkali in the activation process is responsible for the increased immunity of the activated surface. The best immunity was obtained by using a combination of Cs and Li without any loss in near bandgap yield. Optimally activated photocathodes have nearly equal quantities of both alkalis.

  3. DOOCS patterns, reusable software components for FPGA based RF GUN field controller

    Energy Technology Data Exchange (ETDEWEB)

    Pucyk, P. [Institute of Electronic Systems, Warsaw (Poland)

    2006-07-01

    Modern accelerator technology combines software and hardware solutions to provide distributed, high efficiency digital systems for High Energy Physics experiments. Providing flexible, maintainable software is crucial for ensuring high availability of the whole system. In order to fulfil all these requirements, appropriate design and development techniques have to be used. Software patterns are well known solution for common programming issues, providing proven development paradigms, which can help to avoid many design issues. DOOCS patterns introduces new concepts of reusable software components for control system algorithms development and implementation in DOOCS framework. Chosen patterns have been described and usage examples have been presented in this paper. (orig.)

  4. Interpreting the Empirical Evidence on Illegal Gun Market Dynamics

    OpenAIRE

    Braga, Anthony A.; Wintemute, Garen J.; Pierce, Glenn L.; Cook, Philip J.; Ridgeway, Greg

    2012-01-01

    Thousands of Americans are killed by gunfire each year, and hundreds of thousands more are injured or threatened with guns in robberies and assaults. The burden of gun violence in urban areas is particularly high. Critics suggest that the results of firearm trace data and gun trafficking investigation studies cannot be used to understand the illegal supply of guns to criminals and, therefore, that regulatory and enforcement efforts designed to disrupt illegal firearms markets are futile in ad...

  5. Gun utopias? Firearm access and ownership in Israel and Switzerland

    OpenAIRE

    Rosenbaum, Janet

    2011-01-01

    The 2011 attempted assassination of a US representative renewed the national gun control debate. Gun advocates claim that mass-casualty events are mitigated and deterred with three policies: (1) permissive gun laws, (2) widespread gun ownership, (3) encouragement of armed civilians who can intercept shooters, and cite Switzerland and Israel as exemplars. We evaluate these claims with analysis of International Crime Victimization Survey (ICVS) data and translation of laws and original source m...

  6. LCLS-II high power RF system overview and progress

    Energy Technology Data Exchange (ETDEWEB)

    Yeremian, Anahid Dian

    2015-10-07

    A second X-ray free electron laser facility, LCLS-II, will be constructed at SLAC. LCLS-II is based on a 1.3 GHz, 4 GeV, continuous-wave (CW) superconducting linear accelerator, to be installed in the first kilometer of the SLAC tunnel. Multiple types of high power RF (HPRF) sources will be used to power different systems on LCLS-II. The main 1.3 GHz linac will be powered by 280 1.3 GHz, 3.8 kW solid state amplifier (SSA) sources. The normal conducting buncher in the injector will use four more SSAs identical to the linac SSAs but run at 2 kW. Two 185.7 MHz, 60 kW sources will power the photocathode dual-feed RF gun. A third harmonic linac section, included for linearizing the bunch energy spread before the first bunch compressor, will require sixteen 3.9 GHz sources at about 1 kW CW. A description and an update on all the HPRF sources of LCLS-II and their implementation is the subject of this paper.

  7. Cancellation of RF Coupler-Induced Emittance Due to Astigmatism

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC

    2016-12-11

    It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.

  8. Experimental investigation of coaxial-gun-formed plasmas injected into a background transverse magnetic field or plasma

    OpenAIRE

    Zhang, Yue; Hsu, Scott C.; Fisher, Dustin M.; Gilmore, Mark; Lynn, Alan G.

    2017-01-01

    Injection of coaxial-gun-formed magnetized plasmas into a background transverse vacuum magnetic field or into a background magnetized plasma has been studied in the helicon-cathode (HelCat) linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys.81, 345810104 (2015)]. Magnetized plasma jet launched into a background transverse magnetic field shows emergent kink stabilization of the jet due to the formation of a sheared flow in the jet above the kink-stabilizati...

  9. Experimental study on the luminous radiation associated to the field emission of samples submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Luong, M.; Tan, J.; Bonin, B.; Safa, H.

    1996-01-01

    The accelerating gradient of the RF cavities is limited by the strong field emission (FE) of electrons stemming from the metallic walls. Previous experiments evidenced luminous radiations associated with electron emission of cathodes subjected to intense DC electric field. These observations invoked the proposal of new theoretical models of the field emission phenomenon. This experimental study extends the previous DC works to the RF case. A special copper RF cavity has been developed equipped with an optical window and a removable sample. It has been designed for measuring both electron current and luminous radiation emitted by the sample, subjected to maximum RF electric field. The optical apparatus attached to the cavity permits to characterize the radiation in terms of intensity, glowing duration and spectral distribution. The results concerning different niobium or copper samples, whom top was either scratched or intentionally contaminated with metallic or dielectric particles are summarized. (author)

  10. Additive manufacturing of RF absorbers

    Science.gov (United States)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  11. The design of gridded pierce guns for accelerators

    International Nuclear Information System (INIS)

    True, R.

    1985-01-01

    It is vital to employ ultra-laminar beams in electron linacs to maximize charge transport to the target. This paper presents numerical and experimental design techniques which have led to significant improvements in gridded Pierce guns used in microwave tubes and electron linacs. The paper concludes with two gun/injector concepts which have demonstrated enhanced performance over standard triode Pierce guns

  12. Youth, Guns, and the Juvenile Justice System. Research Report.

    Science.gov (United States)

    Butts, Jeffrey; Coggeshall, Mark; Gouvis, Caterina; Mears, Daniel; Travis, Jeremy; Waul, Michelle; White, Ruth

    This report documents trends in youth gun violence and the response within the justice system, noting the growing variety of data resources available to investigate the effect of new gun laws on youth, communities, and public safety. The first section reviews recent trends, examining the major wave of gun violence in the United States during the…

  13. Should Gun Safety Be Taught in Schools? Perspectives of Teachers

    Science.gov (United States)

    Obeng, Cecilia

    2010-01-01

    Background: Gun-related injuries and deaths among children occur at disproportionately high rates in the United States. Children who live in homes with guns are the most likely victims. This study describes teachers' views on whether gun safety should be taught to children in the preschool and elementary years. Methods: A total of 150 survey…

  14. 78 FR 11902 - Review of Gun Safety Technologies

    Science.gov (United States)

    2013-02-20

    ... DEPARTMENT OF JUSTICE Office of Justice Programs [OJP (NIJ) Docket No. 1615] Review of Gun Safety...'s Plan to reduce gun violence released on January 16, 2013, the U.S. Department of Justice, Office... emerging gun safety technologies and plans to issue a report on the availability and use of those...

  15. Gun Violence and Children: Factors Related To Exposure and Trauma.

    Science.gov (United States)

    Slovak, Karen

    2002-01-01

    Study investigated relationship between access to firearms and parental monitoring on rural youths' exposure to gun violence, and examined the effect of gun violence exposure on mental health. Results indicated a substantial number were exposed to gun violence. Exposure was related to firearm access and parental monitoring. Implications for social…

  16. Frequency of Guns in the Households of High School Seniors

    Science.gov (United States)

    Coker, Ann L.; Bush, Heather M.; Follingstad, Diane R.; Brancato, Candace J.

    2017-01-01

    Background: In 2013, President Obama lifted the federal ban on gun violence research. The current study provides one of the first reports to estimate household gun ownership as reported by youth. Methods: In this cohort study of 3,006 high school seniors from 24 schools, we examined the frequency of household guns ownership. Results: About 65%…

  17. Design of a High-Perveance Electron Gun for Electron Cooling in the Low Energy Ion Ring (LEIR) at CERN and Non-Interceptive Proton Beam Profile Monitors using Ion or Atomic Probe Beams

    CERN Document Server

    Dimopoulou, Christina

    2002-01-01

    For an efficient electron cooling of the low-energy Pb54+ ions in LEIR a high-perveance (at least 3.6microperv) electron gun had to be designed. The theoretical study of electron guns has shown that the required perveance can be achieved by using a convex cathode. The gun should be immersed in a strong magnetic field (B=2-6kG) in order to obtain a parallel beam with very low transverse energy (typically 0.1 eV). This idea was confirmed by experimental tests at Fermilab. An adiabatic magnetic expansion is foreseen after the gun in order to reduce the magnetic field to accpetable values (0.6-1 kG) in the cooling section. The internal geometry of a convex cathode gun for the LEIR electron cooler together with the parameters of the magnetic expansion are proposed. The scheme fulfils the requirements. In addition, the author has made an important contribution in the field of beam instrumentation for the LHC and other accelerators at CERN. A profile monitor has been developed that uses a Xe ion probe beam that inte...

  18. Advanced Cathode Electrolyzer (ACE), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a static, cathode-fed, 2000 psi, balanced-pressure Advanced Cathode Electrolyzer (ACE) based on PEM electrolysis technology. It...

  19. Reservoir Cathode for Electric Space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a reservoir cathode to improve performance in both ion and Hall-effect thrusters. We propose to adapt our existing reservoir cathode technology to this...

  20. Highly Efficient Micro Cathode, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek Company, Inc. proposes to develop a micro thermionic cathode that requires extremely low power and provides long lifetime. The basis for the cathode is a...

  1. Advanced Cathode Electrolyzer (ACE), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a static, cathode-fed, 2000 psi, balanced-pressure Advanced Cathode Electrolyzer (ACE) based on PEM electrolysis technology. It...

  2. Mechanistic Enhancement of SOFC Cathode Durability

    Energy Technology Data Exchange (ETDEWEB)

    Wachsman, Eric [Univ. of Maryland, College Park, MD (United States)

    2016-02-01

    Durability of solid oxide fuel cells (SOFC) under “real world” conditions is an issue for commercial deployment. In particular cathode exposure to moisture, CO2, Cr vapor (from interconnects and BOP), and particulates results in long-term performance degradation issues. Here, we have conducted a multi-faceted fundamental investigation of the effect of these contaminants on cathode performance degradation mechanisms in order to establish cathode composition/structures and operational conditions to enhance cathode durability.

  3. Novel Cathodes Prepared by Impregnation Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Eduardo Paz

    2006-09-30

    (1) We showed that similar results were obtained when using various LSM precursors to produce LSM-YSZ cathodes. (2) We showed that enhanced performance could be achieved by adding LSCo to LSMYSZ cathodes. (3) We have preliminary results showing that there is a slow deactivation with LSFYSZ cathodes.

  4. RF Structures for Linac4

    CERN Document Server

    Gerigk, F; Pasini, M; Ramberger, S; Vretenar, M; Wegner, R

    2007-01-01

    Linac4 is proposed to replace the existing proton linac at CERN (Linac2). Using an increased injection energy of 160 MeV instead of 50 MeV, Linac4 is expected to double the beam intensity in the PS Booster (PSB) and will thus be the first step towards higher brightness beams in the LHC. In this paper we re-assess the choice of RF structures for Linac4. Different accelerating structures for different energy ranges are compared in terms of RF efficiency, ease of construction and alignment, and necessary infrastructure. Eventually we present the final choice for Linac4.

  5. rf reference line for PEP

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, H.D.; Weaver, J.N.

    1979-03-01

    A rf phase reference line in 6 segments around the 2200 meter circumference PEP storage ring is described. Each segment of the reference line is phase stabilized by its own independent feedback system, which uses an amplitude modulated reflection from the end of each line. The modulation is kept small and decoupled from the next segment to avoid crosstalk and significant modulation of the rf drive signal. An error evaluation of the system is made. The technical implementation and prototype performance are described. Prototype tests indicate that the phase error around the ring can be held below 1 degree with this relatively simple system.

  6. Green plasticizers for multibase gun propellants (Lecture)

    NARCIS (Netherlands)

    Schoolderman, C.; Driel, C.A. van; Zebregs, M.

    2007-01-01

    TNO Defence, Security and Safety has a long history of research on gun propellants. Areas investigated are formulating (new ingredients, optimization), manufacturing, charge design and lifetime assessment [1,2,3,4,5]. In conventional propellants inert plasticizers are used to alter performance,

  7. Capital Punishment, Gun Ownership, and Homicide.

    Science.gov (United States)

    Kleck, Gary

    1979-01-01

    Examines two controversial questions related to the problem of interpersonal violence in America: (1) Does use of the death penalty exert any measurable influence on the rate of homicide in the United States? (2) What relationship, if any, exists between the level of gun ownership and the level of homicide violence? (Author)

  8. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...

  9. Guns on Campus: A Chilling Effect

    Science.gov (United States)

    Mash, Kenneth M.

    2013-01-01

    The author of this article observes that, while much has been written on the overall topic of safety with regard to allowing guns on college campuses, little has been said about how allowing the possession of deadly weapons can create a "chilling effect" on academic discussions. This article considers how some universities have…

  10. College Students Opinions on Gun Violence.

    Science.gov (United States)

    Lewis, Rhonda K; LoCurto, Jamie; Brown, Kyrah; Stowell, David; Maryman, J'Vonnah; Dean, Amber; McNair, Thoi; Ojeda, Debbie; Siwierka, Julia

    2016-06-01

    Gun violence and control issues have become serious public health problems. This study gathered the opinions from 419 college students from a Midwestern University. Participants were asked about beliefs about purchasing assault weapons, beliefs about bringing handguns to college campuses and beliefs about contributing factors that lead to gun violence. Participants completed surveys online. The findings showed that overall 54 % of respondents believed that military assault weapons should be banned and 53 % agree that teachers should be allowed to carry a registered handgun on campus. There were statistically significant differences between males and females on these issues. For instance, females believed military assault weapons and high capacity magazines should be banned more than 1.9 times (p = .004) p gun violence were decline in parenting and family values (17 %), gang involvement (14 %), bullying (13.8 %) and guns being easy to obtain (13.8 %). Limitations and implications for policy work are discussed.

  11. Youth Suicide and Guns. Firearm Facts.

    Science.gov (United States)

    Duker, Laurie, Ed.

    Whether or not a suicide attempt results in death depends in large part on the method chosen. If a teenager attempts suicide with a gun, his or her death is nearly guaranteed. This brief fact sheet presents data on firearms and suicide, the third leading cause of death for adolescents and young adults in the United States. Any number of societal…

  12. Issue Management and the Australian Gun Debate.

    Science.gov (United States)

    Reynolds, Christopher

    1997-01-01

    Examines the rise and fall of media coverage of the issues of gun control and political conflict in Australia after an incident of mass murder in April 1996. Aims to reveal the issue management process that occurred and the hidden agendas that motivated the political and media activity. Demonstrates the media's role in the creation of issue…

  13. Cerebral damage caused by nail gun injury

    Directory of Open Access Journals (Sweden)

    Andersen Chris Hedeman

    2016-06-01

    Full Text Available Background Accidents with nail guns are rather common, especially in the construction industry. Most injuries involve the extremities and several present with intracerebral injuries. When the patient is unconscious, it can be a big challenge to determine whether the injury is an accident, self-inflicted or a criminal act.

  14. How Sociology Texts Address Gun Control

    Science.gov (United States)

    Tonso, William R.

    2004-01-01

    William R. Tonso has chosen an issue that he knows something about to examine how sociology textbooks address controversy. Appealing for gun control is fashionable, but it is at odds with a fondness that ordinary Americans have for their firearms--one that is supported by a growing body of research on deterrence to crime. There are two sides to…

  15. Safety Plan for Schools: No Guns

    Science.gov (United States)

    Shah, Nirvi

    2013-01-01

    In a pre-emptive move against a school safety proposal from the National Rifle Association that is expected to include a call for more people trained and approved to carry guns at schools, a coalition of civil rights and education groups unveiled its own safety plan last week. It seeks the creation of positive school climates, thoughtful and…

  16. Nerf Guns Strike a Nerve on Campuses

    Science.gov (United States)

    Young, Jeffrey R.

    2008-01-01

    Killing zombies on campus just isn't as much fun as it used to be. Students at Bowling Green State University once carried Nerf guns for a week each semester, shooting the zombies before the creatures could tag them. Participants were seen by most bystanders as nerdy but harmless kids who liked role-playing. These days, bright plastic Nerf guns…

  17. Accidental Bolt Gun Injury to Femur - A Case Report

    OpenAIRE

    Kattimani, Ravi Prasad; Shetty, Sanath; Mirza, Humayun

    2016-01-01

    Introduction: Bolt gun or slaughterer?s guns are used in meat industry for ?humane killing? of animals. Injuries caused by bolt gun are rare, reported exclusively from central European countries. We report a case of 28 year old male, who accidentally shot himself with a bolt gun to his right thigh. Case Report: A 28 years old male presented to our Accident and Emergency department after accidental injury to his right thigh with bolt gun. He had an entry wound measuring 2 cm in length and 1 cm...

  18. Development of the electron gun control system of SSRF

    International Nuclear Information System (INIS)

    Zhou Dayong; Lin Guoqiang; Liu Dekang; Shen Liren

    2010-01-01

    An electron gun is the key part of a linac, the beam quality of which depends on beam quality of the electron gun, hence the need of a stable control system of the electron gun to ensure its safe operation.In this paper, we report our progresses in developing the linac's electron gun control system of Shanghai Synchrotron Radiation Facility (SSRF). It uses PLC as the device controllers, with the monitoring software developed on EPICS. The whole system is connected by Ethernet. The PLC and Ethernet technology ensures good reliability and easy maintenance of the electron gun control system. (authors)

  19. Development and Measurement of Strain Free RF Photoinjector Vacuum Windows

    CERN Document Server

    Biedron, Sandra G

    2004-01-01

    RF photoinjectors produce the highest brightness electron bunches only under nearly ideal illumination by a drive laser. The vacuum window used to introduce the laser beam is an essential element that may potentially degrade any distribution, making it difficult or impossible to know the actual uniformity achieved at the cathode. Because of the necessity to obtain ultrahigh vacuum near the photoinjector, some restrictions are imposed on the fabrication technology available to manufacture distortion-free windows. At the UV wavelengths commonly used for photoinjectors, it is challenging to measure and eliminate degradation caused by vacuum windows. Here, we discuss the initial laser-based measurements of a strain-free, coated, UHV window manufactured by Insulator Seal in collaboration with members of Brookhaven and Argonne National Laboratories.

  20. RF Design of the TW Buncher for the CLIC Drive Beam Injector (2nd report)

    CERN Document Server

    Shaker, Hamed

    2016-01-01

    CLIC is based on the two beams concept that one beam (drive beam) produces the required RF power to accelerate another beam (main beam). The drive beam is produced and accelerated up to 50MeV inside the CLIC drive beam injector. The drive beam injector main components are a thermionic electron gun, three sub-harmonic bunchers, a pre-buncher, a TW buncher, 13 accelerating structures and one magnetic chicane. This document is the second report of the RF structure design of the TW buncher. This design is based on the beam dynamic design done by Shahin Sanaye Hajari due to requirements mentioned in CLIC CDR. A disk-loaded tapered structure is chosen for the TW buncher. The axial electric field increases strongly based on the beam dynamic requirements. This second report includes the study of HOM effects, retuning the cells, study of dimensional tolerances and the heat dissipation on the surface.