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Sample records for cathode rf gun

  1. RF Electron Gun with Driven Plasma Cathode

    CERN Document Server

    Khodak, Igor

    2005-01-01

    It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

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

    International Nuclear Information System (INIS)

    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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-25

    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. An RF excited plasma cathode electron beam gun design

    OpenAIRE

    Del Pozo, S.; Ribton, C; Smith, DR

    2014-01-01

    A plasma cathode electron beam (EB) gun is presented in this work. A radio frequency (RF) excited plasma at 84 MHz was used as the electron source to produce a beam power of up to 3.2 kW at -60 kV accelerating voltage. The pressure in the plasma chamber is approximately 1 mbar. The electrons are extracted from the plasma chamber to the vacuum chamber (at 10-5 mbar) through a diaphragm with a 0.5 mm diameter nozzle. Advantages over thermionic cathode guns were demonstrated empirically. Mainten...

  5. 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.

  6. 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.

  7. Development of a photo-cathode rf electron gun for ultra-short bunch generation

    International Nuclear Information System (INIS)

    The photocathode rf electron gun is a high brightness electron source because the initial electron bunch shape can be controlled by the cathode illuminating laser pulse and then the bunch is rapidly accelerated by the high gradient electric field in the rf gun cavity. The rf guns are widely used not only as a injector for large facility but also application researches. At Waseda University, I and collaborators have been developing an rf electron gun since 1999. We performed optimization of cavity structure, improvement of rf tuner and development of photocathode material, then we succeeded in operating 3.6 cell rf gun. In these backgrounds, I conceived a new type rf gun cavity structure for ultra-short electron bunch generation, named Energy-Chirping-Cell attached rf gun (ECC rf gun). Less than 100 fs (rms) bunch can be produced with 100 pC charge by this ECC rf gun in the simulation. Such a high peak current bunch has a possibility to apply for the coherent THz radiation source and single shot electron diffraction microscope. Encouraged by this successful simulation results, we manufactured an ECC rf gun and measured the bunch length at Waseda University. The experimental results showed a good agreement with simulation and we found that the bunch length from ECC rf gun was less than 500 fs (rms). In this paper, the introduction of the photocathode rf gun, principle and experimental results of ECC rf gun, and future prospective will be described. (author)

  8. Final Technical Report- Back-gate Field Emission-based Cathode RF Electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, Gary; Martin, Allen; Noonan, John

    2010-10-30

    The objective was to complete the design of an electron gun which utilizes a radio frequency (RF) power source to apply a voltage to a field emission (FE) cathode, a so called cold cathode, in order to produce an electron beam. The concept of the RF electron gun was originally conceived at Argonne National Laboratory but never reduced to practice. The research allowed the completion of the design based upon the integration of the FE electron source. Compared to other electron guns, the RF gun is very compact, less than one third the size of other comparable guns, and produces a high energy (to several MeV), high quality, high power electron beam with a long focal length with high repetition rates. The resultant electron gun may be used in welding, materials processing, analytical equipment and waste treatment.

  9. Update on photo cathodes for RF-Guns at DESY

    OpenAIRE

    Schreiber, Siegfried; Hansen, Ingo; Lederer, Sven; Michelato, Paolo; Monaco, Laura; Sertore, Daniele

    2013-01-01

    At DESY, caesium telluride photocathodes are successfully used for the RF Guns at DESY,namely FLASH, PITZ, and REGAE. Their high quantum efficiency and long lifetime allow toproduce routinely thousands of bunches per second with a single bunch charge in the nCrange. We report on the status of the preparation system and updates on lifetime, quantumefficiency, darkcurrent, and operating experience.

  10. Preliminary calculations of ballistic bunch compression with thermionic cathode rf guns

    International Nuclear Information System (INIS)

    Preliminary calculations using the computer code PARMELA indicate that it is possible to achieve peak currents on the order of 1 kA using a thermionic-cathode rf gun and ballistic bunch compression. In contrast to traditional magnetic bunching schemes, ballistic bunch compression uses a series of rf cavities to modify the energy profile of the beam and properly chosen drifts to allow the bunching to occur naturally. The method, suitably modified, should also be directly applicable to photoinjector rf guns. Present work is focusing on simultaneously compressing the bunch while reducing the emittance of the electron beam. At present, the calculated normalized rms emittance is in the neighborhood of 6.8 π mm mrad with a peak current of 0.88 kA, and a peak bunch charge of 0.28 nC from a thermionic-cathode gun

  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. Improvement of beam macropulse properties using slim thermionic cathode in IAE RF gun

    International Nuclear Information System (INIS)

    A long beam macropulse is strongly required for free-electron lasers. RF guns can potentially produce high brightness electron beam using a simple and compact system. However, due to a back-bombardment, a cathode surface is overheated. Thus, it is difficult to maintain a constant beam current and beam energy during a macropulse. The use of a photo cathode with a short-pulsed laser is one of the solutions, but it affects the simplicity and the compactness of the RF guns. We studied a mechanism of back-bombardment and experimentally and numerically found that a low energy component of the back-streaming electrons plays an important role in cathode surface heating

  13. Establishing reliable good initial quantum efficiency and in-situ laser cleaning for the copper cathodes in the RF gun

    International Nuclear Information System (INIS)

    Establishing good initial quantum efficiency (QE) and reliable in-situ cleaning for copper cathode in the RF gun is of critical importance for the RF gun operations. Recent studies on the SLAC RF gun test bed indicated that the pre-cleaning (plasma cleaning) in the test chamber followed by copper cathode exposure to air for cathode change leads to a very low initial QE in the RF gun, and also demonstrated that without the pre-cleaning good initial QE >4×10−5 can be routinely achieved in the RF gun with the cathodes of QE <1×10−7 measured in the test chamber. QE can decay over the time in the RF gun. The in-situ laser cleaning technique for copper cathodes in the RF gun is established and refined in comparison to previous cleaning at the linac coherent light source, resulting in an improved QE and emittance evolutions. The physics of the laser cleaning process is discussed. It is believed that the reflectivity change is one of the major factors for the QE boost with the laser cleaning

  14. Establishing reliable good initial quantum efficiency and in-situ laser cleaning for the copper cathodes in the RF gun

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, F., E-mail: zhoufeng@slac.stanford.edu; Sheppard, J.C.; Vecchione, T.; Jongewaard, E.; Brachmann, A.; Corbett, J.; Gilevich, S.; Weathersby, S.

    2015-05-21

    Establishing good initial quantum efficiency (QE) and reliable in-situ cleaning for copper cathode in the RF gun is of critical importance for the RF gun operations. Recent studies on the SLAC RF gun test bed indicated that the pre-cleaning (plasma cleaning) in the test chamber followed by copper cathode exposure to air for cathode change leads to a very low initial QE in the RF gun, and also demonstrated that without the pre-cleaning good initial QE >4×10{sup −5} can be routinely achieved in the RF gun with the cathodes of QE <1×10{sup −7} measured in the test chamber. QE can decay over the time in the RF gun. The in-situ laser cleaning technique for copper cathodes in the RF gun is established and refined in comparison to previous cleaning at the linac coherent light source, resulting in an improved QE and emittance evolutions. The physics of the laser cleaning process is discussed. It is believed that the reflectivity change is one of the major factors for the QE boost with the laser cleaning.

  15. Research of photo-cathode RF gun and superconducting accelerator experiment

    International Nuclear Information System (INIS)

    Photo-cathode superconducting accelerator experiment system includes Nd: YAG mode-locked laser, Cs2Te cathode, 2 + 1/2 RF gun, L band 3.5 MW microwave source, 1.3 GHz superconducting cavity, 500 W continuous microwave source, coaxial input coupler, 4.2 K cryostat, helium liquefied system, control system, beam diagnosis system, and vacuum system. In June 2001, the experiment of this system was carried out in CAEP. The electron beam energy gained in the superconducting cavity is 0.58 MeV, and the micro-pulse current is 0.1A

  16. 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.

  17. Performance of magnesium cathode in the S-band RF gun

    International Nuclear Information System (INIS)

    In this paper, the authors present the preliminary results of the performance of magnesium cathode in a high frequency RF gun. The quantum efficiency of Mg showed a dramatic improvement upon laser cleaning, increasing from 10-5 to 4 x 10-4 after two hours of cleaning, and to 2 x 10-3 after systematic cleaning. The cleaning procedure for this increase is described in detail. Charge measured as a function of the laser injection phase relative to the RF phase indicates that the temporal variation of the field on the cathode both due to the RF and the shielding effect of the emitted electrons play a critical role in the emission and extraction of electrons. A model that includes this variation is numerically fitted to the measured charge and the results are presented. The unexpected outcome of the fit was the low field enhancement factor (0.1) predicted by the model for the photoemission. The physical origin of this is still under investigation

  18. Characterisation of an RF excited argon plasma cathode electron beam gun

    OpenAIRE

    Del Pozo, S.; Ribton, C; Smith, DR

    2014-01-01

    This work describes the experimental set up used for carrying out spectroscopic measurements in a plasma cathode electron beam (EB) gun. Advantages of plasma cathode guns over thermionic guns are described. The factors affecting electron beam power such as plasma pressure, excitation power and plasma chamber geometry are discussed. The maximum beam current extracted was 53 mA from a 0.5 mm diameter aperture in the plasma chamber. In this work, the electron source is an argon plasma excited at...

  19. RF guns: a review

    International Nuclear Information System (INIS)

    Free Electron Lasers and future linear colliders require very bright electron beams. Conventional injectors made of DC guns and RF bunchers have intrinsic limitations. The recently proposed RF guns have already proven their capability to produce bright beams. The necessary effort to improve further these performances and to gain reliability is now undertaken by many laboratories. More than twenty RF gun projects both thermionic and laser-driven are reviewed. Their specific characteristics are outlined and their nominal performances are given

  20. X-Band RF Gun Development

    International Nuclear Information System (INIS)

    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.

  1. X-Band RF Gun Development

    Energy Technology Data Exchange (ETDEWEB)

    Vlieks, Arnold; Dolgashev, Valery; Tantawi, Sami; /SLAC; Anderson, Scott; Hartemann, Fred; Marsh, Roark; /LLNL, Livermore

    2012-06-22

    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.

  2. Design simulations for a small emittance 2.7-cell photo-cathode rf-gun injector

    International Nuclear Information System (INIS)

    In order to produce the electron bunch with small emittance which is the key issue in the so-called SASE studies, the design studies on a two-and-half cell photo-cathode rf-gun has been conducted. First of all, the main parameters of the rf-gun injector, for example, the cell lengths, the solenoidal strength and the accelerating gradient, were optimized by using the code of Parmela. As a main result, the optimum was found to be a 2.7-cell cavity. The geometry and the coupling scheme of the requested cavity was studied in some detail with the codes, Mafia and Superfish. The beam iris of each cells was enlarged in order to widen the mode separations. For the purpose of cancelling the influence of the coupling iris upon the field symmetry, the so-called symmetrical double-side input coupler was studied. The coupler will be assembled to the second cell and the critical matching has been achieved in the Mafia-T3 simulation. With this cavity, the final normalized rms emittance achieved the value of 0.81 πmm-mrad at a charge of 1nC in the Parmela simulation. (author)

  3. RF Design of the LCLS Gun

    Energy Technology Data Exchange (ETDEWEB)

    Limborg-Deprey, C

    2010-12-13

    Final dimensions for the LCLS RF gun are described. This gun, referred to as the LCLS gun, is a modified version of the UCLA/BNL/SLAC 1.6 cell S-Band RF gun [1], referred to as the prototype gun. The changes include a larger mode separation (15 MHz for the LCLS gun vs. 3.5 MHz for the prototype gun), a larger radius at the iris between the 2 cells, a reduced surface field on the curvature of the iris between the two cells, Z power coupling, increased cooling channels for operation at 120 Hz, dual rf feed, deformation tuning of the full cell, and field probes in both cells. Temporal shaping of the klystron pulse, to reduce the average power dissipated in the gun, has also been adopted. By increasing the mode separation, the amplitude of the 0-mode electric field on the cathode decreases from 10% of the peak on axis field for the prototype gun to less than 3% for the LCLS gun for the steady state fields. Beam performance is improved as shown by the PARMELA simulations. The gun should be designed to accept a future load lock system. Modifications follow the recommendations of our RF review committee [2]. Files and reference documents are compiled in Section IV.

  4. 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.

  5. Development of L-band RF gun

    International Nuclear Information System (INIS)

    Continuing from the report at the previous annual meeting, we show the present status about the development of the L-band photocathode RF gun which is conducted by the collaborations with the groups of Osaka University, KEK, and Hiroshima University. At the last summary, we carried out the high power test and RF processing of the RF-gun cavity at KEK's Superconducting radiofrequency Test Facility (STF). Comparing with the predecessor working at STF, we find that the RF process of this cavity make faster progress. In this report, we show the result of this high power RF processing of the cavity and the present problems found out after that. We also show the development of the laser system as the cathode driver. (author)

  6. Measurement of field emission current from a coniferous-tree-type carbon nanostructure cathode by using a C-band RF gun

    International Nuclear Information System (INIS)

    We have fabricated a C-band RF gun which used the Coniferous-tree-type Carbon NanoStructure (CCNS) cathode aiming at development of a tabletop size high-energy x-ray source and a terahertz radiation source. The CCNS is having structure like coniferous forest formed by carbon nanostructures. Tips of it have a nanometer-size tubular structure that becomes thicker on the substrate side. Owing to this configuration, the CCNS has a large field enhancement factor, and is considered to be more stable in high electric fields than Carbon nanotubes. The C-band RF gun is a single cell pillbox cavity of the 16.1 mm length and is designed to work around the frequency of 5325 MHz. An important quantity for the CCNS cathode which is called field enhancement factor was measured by applying the electric field from 18.8 to 26.7 MV/m. The field enhancement factor was evaluated as 860 and this value is consistent with the result measured by an electrostatic field. (author)

  7. Design simulations for a small emittance 2.7-cell photo-cathode rf-gun in jector

    Science.gov (United States)

    Yongzhang, Huang

    1997-05-01

    In order to produce the electron bunch with small emittance which is the key issue in the so-called SASE studies, the design studies on a two-and-half cell photocathode rf-gun has been conducted. The rf gun injector is optimized by using the code of Par mela. As a main result, the optimum is found to be a 2.7-cell cavity. The geometry and the coupling scheme of the requested cavity is studied in more detail with the codes of Mafia and Superfish. The beam iris of each cells is enlarged in order to wide n the mode separations. For the purpose of cancelling the influence of the coupling iris upon the field symmetry, the so-called symmetrical double-side input coupler is studied. The coupler will be assembled to the second cell and the critical matchin g has been achieved in the Mafia-T3 simulation. With this cavity, the final normalized rms emittance reaches the value of 0.81πmm-mrad at a charge of 1nC in the Parmela simulation.

  8. 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.

  9. Method of electron emission control in RF guns

    International Nuclear Information System (INIS)

    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

  10. Cathode Ion Bombardment in RF Photoguns

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-09-01

    In this paper, we use the method of rapid oscillating field to solve the equation of ion motion in an RF gun. 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 proposes a simple mitigation recipe that can reduce the rate of ion bombardment.

  11. rf-induced beam dynamics in rf guns and accelerating cavities

    OpenAIRE

    Floettmann, Klaus

    2015-01-01

    In this paper, a detailed discussion of the rf-related beam dynamics in rf guns and accelerating cavities is presented. Other rf-gun-related aspects such as space charge and cathode physics are not treated. An effective start phase is introduced in order to yield a better description for the synchronous phase, the energy gain, and the bunch compression factor in gun cavities. Energy spread and longitudinal emittance are treated in a form applicable to guns as well as to accelerating cavities....

  12. 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.

  13. Testing a GaAs cathode in SRF gun

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-03-28

    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{sup -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 {approx}10{sup -9} Torr. This destroys the GaAs's NEA surface. The SRF guns combine the excellent vacuum conditions of DC guns and

  14. Photocathode RF guns

    International Nuclear Information System (INIS)

    Free-electron oscillators and amplifiers require electron accelerators capable of delivering pulse trains of electron bunches of high charge density in a wiggler or undulator. A high electron density implies a high peak current (100 A to 2000 A) and a low transverse beam emittance ( 8 nC in picoseconds) with extremely small emittances (< 10 π x mm x mrad). Several approaches have been proposed to attain such performance. This article discusses the use of photocathodes in attaining the aforementioned performance requirements. Photocathodes have been used as electron sources in lasertrons and for the production of spin-polarized electrons. A photocathode is a light-activated electron source that gives unprecedented control over all aspects of the electron distribution: peak current, spatial profile, and temporal profile. This control is possible because the electron distribution is not determined by grids or a cathode, but rather by an incident laser pulse on the photocathode. 44 references, 21 figures

  15. Design of S-band RF photocathode gun

    International Nuclear Information System (INIS)

    A linear electron accelerator used for medical or industrial applications needs moderate beam currents of about 120 mA (peak). In such cases the emittance or the energy spread are not very critical parameters. The Pierce type gun with the standing wave linac is suitable for such applications where emittance of the order of 15 π-mm-mrad or more is acceptable. In contrast, the RF photo cathode gun can be used to achieve emittance of the order of 3 to 5 π-mm-mrad at a charge of about 1 nC. In an RF photo cathode gun, laser pulses will strike the photo cathode to produce electron bunches. This paper presents the basic technologies needed for successful implementation of RF gun mainly for an activity like the inverse Compton source. The proposed design is presented with detailed calculations and simulations for operating the RF gun in multi bunch mode. The gun will be operating at 2998 MHz frequency and the expected energy gain is a 5 MeV using a 10 MW Klystron. A multi bunch train with 1 nC charge per bunch and 100 bunches per train will be accelerated such that the peak to peak energy difference is less than 1%. (author)

  16. On the theory of photocathode rf guns

    Institute of Scientific and Technical Information of China (English)

    GAO Jie

    2009-01-01

    In this paper we give a set of analytical formulae to describe the characteristics of photocathode rf guns at any rf frequencies, such as energy, energy spread, bunch length, out going current, and emittance etc.as functions of the laser injection phase, which are useful in the design and practical operation of rf guns.

  17. A double-frequency rf gun for field emission

    International Nuclear Information System (INIS)

    Cold cathodes have attracted a lot of attention in the field of accelerators in recent years. While the development of suitable cold cathodes is in progress, attempts have been made to combine the cold cathode with a rf structure. Due to the strong dependence on the electric field, field emissions peak at the wave crest, which is not the best injection phase, during a rf cycle. To make the injection phase adjustable, a flexible double-frequency rf gun is designed. The addition of a 3rd-harmonic field to the fundamental one in the half cell will move the wave crest toward a better injection phase and make the initial bunch length shorter. The full cell is resonant at the fundamental frequency. Since only the half cell is resonant at two frequencies, the gun can be easily tuned. Simulations show that the time-dependent rf effects on the transverse and longitudinal phase spaces of the electron bunch can be reduced by choosing proper rf parameters and the space charge effects can be compensated for by using an external solenoid field. Therefore, the gun is able to provide low emittance, low energy spread and short electron bunches with high average current

  18. Beam dynamics studies for photocathode RF gun

    International Nuclear Information System (INIS)

    Photocathode RF guns are very popular choice as injector for low emittance beams especially to light sources world wide. In demand for these gun is increasing steadily and efforts are on to make 2.6 cell RF Gun as SAMEER as proto type for future use at various laboratories. The base design of this 2.6 cell RF Gun is ready and fabrication is planned in near future. In this paper, we present beam dynamic study results of the gun and methodology to arrive at the operating point. Simulation results for Gaussian with nano-second pulse length will be discussed in detail and proposal for generation of few MeV beam will be presented. (author)

  19. 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.

  20. 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.

  1. Higher-order mode rf guns

    Science.gov (United States)

    Lewellen, John W.

    2001-04-01

    Traditional photocathode rf gun design is based around the use of TM0,1,0-mode cavities. This is typically done in the interest of obtaining the highest possible gradient per unit supplied rf power and for historical reasons. In a multicell, aperture-coupled photoinjector, however, the gun as a whole is produced from strongly coupled cavities oscillating in a π mode. This design requires very careful preparation and tuning, as the field balance and resonant frequencies are easily disturbed. Side-coupled designs are often avoided because of the dipole modes introduced into the cavity fields. This paper proposes the use of a single higher-order mode rf cavity in order to generate the desired on-axis fields. It is shown that the field experienced by a beam in a higher-order mode rf gun is initially very similar to traditional 1.5- or 2.5-cell π-mode gun fields, and projected performance in terms of beam quality is also comparable. The new design has the advantages of much greater ease of fabrication, immunity from coupled-cell effects, and simpler tuning procedures. Because of the gun geometry, the possibility also exists for improved temperature stabilization and cooling for high duty-cycle applications.

  2. Spectral Analysys of Charge Emission Spatial Inhomogeneities and Emittance Dilution in RF Guns

    CERN Document Server

    Quattromini, Marcello; Ronsivalle, Concetta

    2004-01-01

    The effects of fluctuations in cathode's quantum efficiency and other sources of dishomogeneities in the performances of a typical RF photoinjector have been investigated with TREDI numerical simulations. The RF gun layout includes a focusing solenoid in a configuration aimed at minimizing the emittance growth due to space charge effects.

  3. Simulation of an rf thermionic gun

    Science.gov (United States)

    Liu, Hongxiu

    1991-07-01

    An rf thermionic gun is simulated using Superfish and Parmela. A strong front-end compression for the bunch is demonstrated. The energy spread, phase spread and emittance of a single electron micropulse are examined subtly by cutting the bunch into slices corresponding to different initial emission phases of the particles.

  4. Beam loading compensation in thermionic RF gun by using RF detuning

    International Nuclear Information System (INIS)

    A new beam energy compensation method was investigated, which can suppress the beam energy drop in a thermionic RF gun caused by the beam current increase due to the back-bombardment effect. The method is to feed a RF power with slightly higher (detuned) frequency to the gun. The principle of this method is based on that the increment of the beam conductance could be cancelled out by the increment of beam suceptance. As a result of numerical simulation, the increase of current density on the cathode surface from 47 to 176 A/cm2 can be compensated by 550 kHz detuned RF power. Results of experiment showed a good agreement with the simulation, and the effectiveness of this method was demonstrated. (author)

  5. Performance review of thermionic electron gun developed for RF linear accelerators at RRCAT

    International Nuclear Information System (INIS)

    RRCAT is engaged in development of RF electron linear accelerator for irradiation of industrial and agricultural products. Thermionic electron gun is primary source for this accelerator as beam current in the RF accelerator is modest and thermionic emission is most prevalent option for electron gun development. An electron gun has to meet high cathode emission capability, low filament power, good accessibility for cathode replacement and should provide short time for maintenance. Electron linear accelerator up to beam energy of 10 MeV require electron source of 45-50 keV beam energy and emission current of 1 A. Electron optics of gun and electron beam profile simulations were carried out using CST's particle tracking code and EGUN code. Triode type electron gun of cathode voltage 50 kV pulsed has been designed, developed and integrated with 10 MeV electron linear accelerators at RRCAT. Beam current of more than 600 mA has been measured with faraday cup in the test stand developed for characterizing the electron gun. Two accelerators one is imported and another one developed indigenously has been energized using this electron gun. Beam energy of 5-10 MeV has been achieved with beam current of 250-400 mA by integrating this electron gun with the linear accelerator. This paper reviews the performance of indigenously developed electron gun for both linear accelerators. (author)

  6. 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

  7. Femtosecond electron microscopy using photocathode RF gun

    International Nuclear Information System (INIS)

    The revealing and understanding of ultrafast structural-change induced dynamics are essential not only in physics, chemistry and biology, but also are indispensable for the development of new materials, new devices and applications. Both new RF gun based ultrafast relativistic electron diffraction and microscopy (UED and UEM) have being developed in Osaka University to probe directly structural changes at the atomic scale with sub-100 fs temporal resolution in materials. The first prototype of relativistic-energy UEM using a femtosecond photocathode RF gun has been developed. Both ultrafast diffraction and image measurements have been succeeded using a femtosecond electron beam. In this paper, the development of the UEM prototype and the first experiments of relativistic-energy electron imaging will be reported. (author)

  8. Fabrication and low-power RF test of C-band RF gun

    International Nuclear Information System (INIS)

    A C-band RF gun for compact radiation sources such as high-energy X-ray and terahertz radiation sources is developed at AIST and is designed to work at a frequency of 5.3 GHz. The total length of this equipment is about 1.5 m. An electron beam with a maximum energy of 0.9 MeV can be generated when the peak electric field is 85 MV/m, corresponding to an RF peak power of 600 kW. A coniferous-tree-type carbon nanostructure is used for the field emission cathode. We present the structural design and fabrication of the C-band RF cavity and a low-power RF test of it

  9. Design, analysis and cold test of a 17 GHz RF Gun

    Science.gov (United States)

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

    1999-07-01

    We analyzed and cold tested a 17 GHz 1-1/2-cell RF gun cavity excited through two coupling holes in the broad wall of a rectangular waveguide. An equivalent circuit theory and an advanced field theory were developed to describe the excitation of an 1-1/2-cell RF gun cavity. SUPERFISH was used to calculate the majority of the equivalent circuit elements as well as the field theory parameters. The matching values of magnetic polarizabilities of the coupling holes were determined by comparing the theory with the measurements. The field theory results were used to model the electric field distribution and accelerating gradient in the RF gun cavity. From this analysis we concluded that the RF gun cavity support gradients as high as 300 MV/m at the cathode without breakdown.

  10. Design, analysis and cold test of a 17 GHz RF Gun

    International Nuclear Information System (INIS)

    We analyzed and cold tested a 17 GHz 1-1/2-cell RF gun cavity excited through two coupling holes in the broad wall of a rectangular waveguide. An equivalent circuit theory and an advanced field theory were developed to describe the excitation of an 1-1/2-cell RF gun cavity. SUPERFISH was used to calculate the majority of the equivalent circuit elements as well as the field theory parameters. The matching values of magnetic polarizabilities of the coupling holes were determined by comparing the theory with the measurements. The field theory results were used to model the electric field distribution and accelerating gradient in the RF gun cavity. From this analysis we concluded that the RF gun cavity support gradients as high as 300 MV/m at the cathode without breakdown

  11. Development of fiber laser for photo cathode electron gun

    International Nuclear Information System (INIS)

    We develop L-band photocathode RF gun which is conducted by the collaborations with the groups of Osaka University, KEK and Hiroshima University. For the photocathode, we uniquely develop laser at Osaka University. At the first laser system, we have developed passive mode lock Yb fiber laser at repetition rate of 108MHz. on the other hand, thermionic cathode electron gun generates electron with sub harmonic buncher with the repetition of 27MHz now in addition to 108MHz. For this reason, we started to develop passive mode lock Yb fiber laser at repetition rate of 27MHz uniquely. The mean power at pulse is 35∼70mW, and Max energy at a pulse is 2.7nJ. (author)

  12. Improving the beam quality of rf guns by correction of rf and space-charge effects

    International Nuclear Information System (INIS)

    In this paper we describe two possible strategies to attain ultra-low emittance electron beam generation by laser-driven RF guns. The first one is based on the exploitation of multi-mode resonant cavities to neutralize the emittance degradation induced by RF effects. Accelerating cigar-like (long and thin) electron bunches in multi-mode operated RF guns the space charge induced emittance is strongly decreased at the same time: high charged bunches, as typically requested by future TeV e-e+ colliders, can be delivered by the gun at a quite low transverse emittance and good behaviour in the longitudinal phase space, so that they can be magnetically compressed to reach higher peak currents. The second strategy consists in using disk-like electron bunches, produced by very short laser pulses illuminating the photocathode. By means of an analytical study a new regime has been found, where the normalized transverse emittance scales like the inverse of the peak current, provided that the laser pulse intensity distribution is properly shaped in the transverse direction. Preliminary numerical simulations confirm the analytical predictions and show that the minimum emittance achievable is set up, in this new regime, by the wake-field interaction between the bunch and the cathode metallic wall

  13. Simulations of Ion Migration in the LCLS RF Gun and Injector

    International Nuclear Information System (INIS)

    The motivation for this work was the observed surface contamination of the first LCLS RF gun copper cathode. We will present the results of simulations in regards to ion migration in the LCLS gun. Ions of residual gases will be created by interaction of molecular gas species with the UV drive laser beam and by the electron beam itself. The larger part of those ionized molecules remain in the vicinity of creation, are transported towards beam line walls or away from the cathode. However a small fraction gains enough kinetic energy, focused by RF and magnetic fields and propagates to the cathode, producing an undesirable increase of the cathode's surface work function. Although this fraction is small, during long term operation, this effect may become a significant factor limiting the source performance.

  14. Beam tail effect of performance-enhanced EC-ITC RF gun

    CERN Document Server

    Hu, Tong-ning; Qin, Bin; Chen, Qu-shan

    2013-01-01

    Beam tail effect of multi-bunches will influence the electron beam performances in high intensity thermionic RF gun. Beam dynamic calculations that illustrate the working states of single and multi-pulse fed-in of performance-enhanced EC-ITC (External Cathode Independent Tunable Cavity) RF gun for FEL (Free Electron Laser) injector are performed to estimate extracted bunch properties. By using both Parmela and homemade MATLAB codes, the effects of single beam tail as well as interactions of multi-pulses are analyzed, where ring-based electron algorithm is adopted to calculated RF fields and space charge field. Furthermore, the procedure of unexpected deviated-energy particles mixed with effective bunch head is described by MATLAB code as well. As a result, performance-enhanced EC-ITC RF gun is proved to have the capability to extract continual stable bunches which are suitable for high requirement THz-FEL.

  15. Simulation of an rf gun injector for the Beijing free electron laser

    Science.gov (United States)

    Liu, Hongxiu

    1990-09-01

    An rf gun injector is being developed in the Institute of High Energy Physics, Academia Sinica. It will be used for a 30 MeV, 2856 MHz disk-loaded travelling-wave linac to drive the Beijing free electron laser (BFEL). It consists of an rf thermionic gun with a LaB 6 cathode and an achromatic but nonisochronic alpha magnet serving as the momentum filter. The transverse and longitudinal dynamics of a single electron bunch were simulated using SUPERFISH and PARMELA. The injector performance was examined in the light of the simulation results.

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

    Science.gov (United States)

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

    2014-02-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rimjaem, S., E-mail: sakhorn.rimjaem@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand); Kusoljariyakul, K.; Thongbai, C. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand)

    2014-02-01

    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{sup ©}. 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.

  18. Cold Test Measurements on the GTF Prototype RF Gun

    Energy Technology Data Exchange (ETDEWEB)

    Gierman, S.M.

    2010-12-03

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. Based on longitudinal phase space measurements showing a correlated energy spread the gun was removed and re-characterized in 2002. The low power RF measurements performed on the gun are described below. Perturbative bead measurements were performed to determine the field ratio in the two-cell gun, and network analyzer measurements were made to characterize the mode structure. A second probe was installed to monitor the RF field in the first cell, and a diagnostic was developed to monitor the high-power field ratio. Calibration of the RF probes, a model for analyzing RF measurements, and Superfish simulations of bead and RF measurements are described.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; Jongewaard, Erik; Lewandowski, James; Limborg-Deprey, Cecile; Li, Zenghai; Schmerge, John; Vlieks, Arnold; Wang, Juwen; Xiao, Liling; /SLAC

    2008-09-24

    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

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

    International Nuclear Information System (INIS)

    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

  1. Finite element analyses for RF photoinjector gun cavities

    International Nuclear Information System (INIS)

    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.)

  2. The system of RF beam control for electron gun

    Science.gov (United States)

    Barnyakov, A. M.; Chernousov, Yu. D.; Ivannikov, V. I.; Levichev, A. E.; Shebolaev, I. V.

    2015-06-01

    The system of RF control of three-electrode electron gun current is described. It consists of a source of microwave signal, coaxial line, coaxial RF switch and RF antenna lead. The system allows one to get the electron beam in the form of bunches with the frequency of the accelerating section to achieve the capture of particles in the acceleration mode close to 100%. The results of calculation and analysis of the elements of the system are presented. Characteristics of the devices are obtained experimentally. The results of using RF control in three-electrode electron gun at electron linear accelerator are described.

  3. The system of RF beam control for electron gun

    International Nuclear Information System (INIS)

    The system of RF control of three-electrode electron gun current is described. It consists of a source of microwave signal, coaxial line, coaxial RF switch and RF antenna lead. The system allows one to get the electron beam in the form of bunches with the frequency of the accelerating section to achieve the capture of particles in the acceleration mode close to 100%. The results of calculation and analysis of the elements of the system are presented. Characteristics of the devices are obtained experimentally. The results of using RF control in three-electrode electron gun at electron linear accelerator are described

  4. Development of a C-band RF gun

    International Nuclear Information System (INIS)

    A C-band RF gun for compact radiation sources such as a high energy x-ray and a terahertz radiation is developed at AIST, which is designed to work at the frequency of 5325 MHz. It consists of a 0.57-cell C-band cavity, a wave guide with a pressurization window, a directional coupler, a four-port circulator, and a 600 kW magnetron. The total length of this equipment is about 1.5 m. An electron beam with the energy of 0.9 MeV can be generated when a peak electric field is 85 MV/m, corresponding to a RF peak power of 600 kW. A coniferous tree type carbon nano structure (CCNS) is used for a field emission cathode. We have fabricated the copper cavity after a cold test of the aluminum cavity. We will present the structure design and fabrication of a C-band copper cavity and the generation of the radiofrequency from the magnetron. (author)

  5. In situ Observation of Dark Current Emission in a High Gradient RF Photocathode Gun

    CERN Document Server

    Shao, Jiahang; Baryshev, Sergey V; Chen, Huaibi; Conde, Manoel; Gai, Wei; Ha, Gwanghui; Jing, Chunguang; Shi, Jiaru; Wang, Faya; Wisniewski, Eric

    2016-01-01

    Undesirable electron field emission (a.k.a. dark current) in high gradient RF photocathode guns deteriorates the quality of photoemission current and limits the operational gradient. To improve the understanding of dark current emission, a high-resolution (~100 um) dark current imaging experiment has been performed in an L-band photocathode gun operating at ~100 MV/m of surface gradient. Dark current from the cathode has been observed to be dominated by several separated strong emitters. The field enhancement factor, beta, of selected regions on the cathode has been measured. The post scanning electron microscopy (SEM) and white light interferometer (WLI) surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred.

  6. In Situ Observation of Dark Current Emission in a High Gradient rf Photocathode Gun

    Science.gov (United States)

    Shao, Jiahang; Shi, Jiaru; Antipov, Sergey P.; Baryshev, Sergey V.; Chen, Huaibi; Conde, Manoel; Gai, Wei; Ha, Gwanghui; Jing, Chunguang; Wang, Faya; Wisniewski, Eric

    2016-08-01

    Undesirable electron field emission (also known as dark current) in high gradient rf photocathode guns deteriorates the quality of the photoemission current and limits the operational gradient. To improve the understanding of dark current emission, a high-resolution (˜100 μ m ) dark current imaging experiment has been performed in an L -band photocathode gun operating at ˜100 MV /m of surface gradient. Scattered strong emission areas with high current have been observed on the cathode. The field enhancement factor β of selected regions on the cathode has been measured. The postexaminations with scanning electron microscopy and white light interferometry reveal the origins of ˜75 % strong emission areas overlap with the spots where rf breakdown has occurred.

  7. A High-Gradient CW R Photo-Cathode Electron Gun for High Current Injectors

    Energy Technology Data Exchange (ETDEWEB)

    Robert Rimmer

    2005-05-01

    The paper describes the analysis and preliminary design of a high-gradient photo-cathode RF gun optimized for high current CW operation. The gun cell shape is optimized to provide maximum acceleration for the newly emitted beam while minimizing wall losses in the structure. The design is intended for use in future high-current high-power CW FELs but the shape optimization for low wall losses may be advantageous for other applications such as XFELs or Linear Colliders using high peak power low duty factor guns where pulse heating is a limitation. The concept allows for DC bias on the photocathode in order to repel ions and improve cathode lifetime.

  8. Temperature controlled cathode heating in the electron gun

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav

    Brno: CSMS, 2002 - (Frank, L.), s. 69 - 70 ISBN 80-238-8749-1. [CSEM. Vranovská Ves (CZ), 08.02.2002-09.02.2002] Institutional research plan: CEZ:AV0Z2065902 Keywords : directly heated tungsten cathode * electron gun * temperature controlled cathode heating Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  9. Magnetron Driven L Band RF Gun using a Photocathode Emitter

    Science.gov (United States)

    Evans, Kirk; Fisher, Amnon; Friedman, Moshe

    1996-11-01

    Magnetron Driven L Band RF Gun using a Photocathode Emitter A tunable 5 megawatt L-Band injection locked magnetron amplifier is used to drive a 1-1/2 cell RF cavity gun, to produce a 2.5 megavolt electron beam. A tunable RF source relaxes the precision of the cavity gun construction, and therefore simplifies the design and reduces the overall cost. The design of the L-Band ( 1.3 GHz) RF cavity linear accelerator is presented, along with Superfish, SOS computer simulations, and calculations of beam energy and temporal qualities. Measurements of a few robust photocathode materials as well as measurements of the beam qualities of the final accelerator are presented. Future work will utilize new semiconductor laser diodes that can be electrically driven in the gigahertz range. This makes possible an electron gun system which can run at the RF frequency used to accelerate the electron beam. Such a system produces a "lock to clock" and synchronized RF and electron beam source which can be run single shot or any rep rate up to the RF frequency.

  10. Comparative simulation studies of plasma cathode electron (PCE) gun

    International Nuclear Information System (INIS)

    Pseudospark discharge based plasma cathode has capability to provide high current density electron beam during discharge process. In this paper an effort has been made to simulate the breakdown processes in the pseudospark discharge based plasma cathode electron gun. The two-dimensional plasma simulation codes VORPAL and OOPIC-Pro have been used and results are compared. The peak discharge current in the plasma cathode electron gun is found to be dependent on aperture size, hollow cathode dimensions, anode voltage and seed electrons energy. The effect of these design parameters on the peak anode current has been analysed by both the codes and results matches well within 10% variation. For the seed electron generation an electron beam trigger source is used to control the discharge process in the hollow cathode cavity. The time span of trigger source has been varied from 1-100 ns to analyze the effect on the peak anode current.

  11. Emittance measurement and optimization for the photocathode RF gun with laser profile shaping

    International Nuclear Information System (INIS)

    The Laser Undulator Compact X-ray source (LUCX) is a test bench for a compact high brightness X-ray generator, based on inverse Compton Scattering at KEK, which requires high intensity multi-bunch trains with low transverse emittance. A photocathode RF gun with emittance compensation solenoid is used as an electron source. Much endeavor has been made to increase the beam intensity in the multi-bunch trains. The cavity of the RF gun is tuned into an unbalanced field in order to reduce space charge effects, so that the field gradient on the cathode surface is relatively higher when the forward RF power into gun cavity is not high enough. A laser profile shaper is employed to convert the driving laser profile from Gaussian into uniform. In this research we seek to find the optimized operational conditions for the decrease of the transverse emittance. With the uniform driving laser and the unbalanced RF gun, the RMS transverse emittance of a 1 nC bunch has been improved effectively from 5.46 πmm.mrad to 3.66 πmm·mrad. (authors)

  12. Polarized RF guns for linear colliders: An ICFA Workshop

    Energy Technology Data Exchange (ETDEWEB)

    D.A. Edwards

    2002-01-31

    The ICFA Workshop on Polarized RF Guns for Linear Colliders was held at Fermilab during April 18-20, 2001. It was attended by 37 scientists from 14 institutions. A list of participants is appended. An RF photoemission gun that delivers polarized electrons at low emittance would be an attractive electron source for a linear collider. Moreover, recently it has been demonstrated that an RF gun in conjunction with nearby injection system optics can deliver a beam with a high ratio of transverse emittances; a simplification of a linear collider's damping system could result. However, at present RF electron gun technology has not developed sufficiently to assure that such a source is feasible. The purpose of the workshop was to review the status of polarized RF gun development with linear collider application in mind, and outline a possible program for the future. A table lists the requirements for the electron injector for proposed linear colliders. The specifications are given for the beam before and after the electron damping ring.

  13. Simulations of Field-Emission Electron Beams from CNT Cathodes in RF Photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Mihalcea, Daniel [NIU, DeKalb; Faillace, Luigi [RadiaBeam Tech.; Panuganti, Harsha [NIU, DeKalb; Thangaraj, Jayakar C.T. [Fermilab; Piot, Philippe [NIU, DeKalb

    2015-06-01

    Average field emission currents of up to 700 mA were produced by Carbon Nano Tube (CNT) cathodes in a 1.3 GHz RF gun at Fermilab High Brightness Electron Source Lab. (HBESL). The CNT cathodes were manufactured at Xintek and tested under DC conditions at RadiaBeam. The electron beam intensity as well as the other beam properties are directly related to the time-dependent electric field at the cathode and the geometry of the RF gun. This report focuses on simulations of the electron beam generated through field-emission and the results are compared with experimental measurements. These simulations were performed with the time-dependent Particle In Cell (PIC) code WARP.

  14. 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.

  15. 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...

  16. RF gun for an intense THz radiation source

    Institute of Scientific and Technical Information of China (English)

    GU Qiang; ZHAO Zhen-Tang; TONG De-Chun; CHEN Li-Fang; XU Xiu-Min

    2008-01-01

    A new facility is under construction at the Shanghai Institute of Applied Physics,to generate femto-second electron bunches and intense coherent THz radiation pulses.A thermionic RF-gun is used to be the electron source of the linac,which is 1.6 cell,π/2,side coupled in design.In the following of this paper,the design,manufacture and beam operation of this gun are presented.

  17. The Properties of Normal Conducting Cathodes in FZD Superconducting Gun

    CERN Document Server

    Xiang, R; Buettig, H; Janssen, D; Justus, M; Lehnert, U; Michel, P; Murcek, P; Schamlott, A; Schneider, Ch; Schurig, R; Staufenbiel, F; Teichert, J

    2009-01-01

    The superconducting radio frequency photoinjector (SRF photoinjector) is one of the latest applications of SC technology in the accelerator field. Since superconducting cathodes with high QE are not available up to now, normal conducting cathode material is the main choice for the SRF photoinjectors. However, the compatibility between the cathode and the cavity is one of the challenges for this concept. The SRF gun with Cs2Te cathode has been successfully operated under the collaboration of BESSY, DESY, FZD, and MBI. In this paper, some experience gained in the gun commissioning will be concluded. The results of the properties of Cs2Te photocathode in the cavity will be presented, such as the Q.E., the life time, the dark current and the thermal emittance.

  18. RF and space-charge effects in laser-driven rf electron guns

    International Nuclear Information System (INIS)

    The evolution of the electron-beam phase space distribution in laser-driven rf guns is studied by taking into account both the time variation of the RF field and space-charge effects. In particular, simple formulas are derived for the transverse and longitudinal emittances at the exit of the gun. The results are compared and found to agree well with those from simulation. 10 refs., 7 figs

  19. Ultra-low emittance X-band photocathode RF gun

    Institute of Scientific and Technical Information of China (English)

    TANG Chuan-Xiang; LIU Xiao-Han

    2009-01-01

    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 type coupler is adopted in this gun and an initial simulation by MAFIA is also given in this paper.

  20. High Power Beam Test and Measurement of Emittance Evolution of a 1.6-Cell Photocathode RF Gun at Pohang Accelerator Laboratory

    Science.gov (United States)

    Park, Jang-Ho; Park, Sung-Ju; Kim, Changbum; Parc, Yong-Woon; Hong, Ju-Ho; Huang, Jung-Yun; Xiang, Dao; Wang, Xijie; Ko, In Soo

    2007-04-01

    A Brookhaven National Laboratory (BNL) GUN-IV type photocathode rf gun has been fabricated to use in femtosecond electron diffraction (FED), femtosecond far infrared radiation (fs-FIR) facility, and X-ray free electron laser (XFEL) facilities at the Pohang Accelerator Laboratory (PAL). The gun consists of a 1.6-cell cavity with a copper cathode, a solenoid magnet, beam diagnostic components and auxiliary systems. We report here the measurement of the basic beam parameters which confirm a successful fabrication of the photocathode RF gun system. The emittance evolution is measured by an emittance meter and compared with the PARMELA simulation, which shows a good agreement.

  1. Emittance Studies of the BNL/SLAC/UCLA 1.6 Cell Photocathode RF Gun

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, D.T.; /SLAC; Wang, X.J.; /Brookhaven; Miller, R.H.; /SLAC; Babzien, M.; Ben-Zvi, I.; /Brookhaven; Pellegrini, C.; /UCLA; Sheehan, J.; Skaritka, J.; /Brookhaven; Winick, H.; /SLAC; Woodle, M.; Yakimenko, V.; /Brookhaven

    2011-09-09

    The symmetrized 1.6 cell S-band photocathode gun developed by the BNL/SLAC/UCLA collaboration is in operation at the Brookhaven Accelerator Test Facility (ATF). A novel emittance compensation solenoid magnet has also been designed, built and is in operation at the ATF. These two subsystems form an emittance compensated photoinjector used for beam dynamics, advanced acceleration and free electron laser experiments at the ATF. The highest acceleration field achieved on the copper cathode is 150 MV/m, and the guns normal operating field is 130 MV/m. The maximum rf pulse length is 3 {mu}s. The transverse emittance of the photoelectron beam were measured for various injection parameters. The 1 nC emittance results are presented along with electron bunch length measurements that indicated that at above the 400 pC, space charge bunch lengthening is occurring. The thermal emittance, {epsilon}{sub o}, of the copper cathode has been measured.

  2. 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.

  3. Simulation studies on back bombardment of electrons in rf thermionic guns

    Science.gov (United States)

    Liu, Hongxiu

    1991-05-01

    Using SUPERFISH and PARMELA, we simulate the back bombardment dynamics of electrons in rf thermionic guns. First, we shed light on some basic physical pictures of the back bombardment by means of the simulation results. Then the solution to this problem is investigated through applying a transverse magnetic field vertically traversing the cathode cavity. The Glaser profile is assumed for the magnetic field. It shows that for the total emitted charge of 1.65 nC and the rf duty factor of 2.5×10 -5 the average back bombardment power can be reduced from more than 10 W to about 2 W with the varying magnetic field up to 150 G. The influence of the magnetic field on the normal electrons out of the gun cavity is examined. The correction to this influence is investigated. Some conclusions are drawn finally.

  4. Demonstration of Cathode Emittance Dominated High Bunch Charge Beams in a DC gun-based Photoinjector

    CERN Document Server

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

    2015-01-01

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (greater than or equal to 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 emittance 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 (ERLs) and Free Electron Lasers (FELs).

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

    International Nuclear Information System (INIS)

    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

  6. Beam tail effect of a performance-enhanced EC-ITC RF gun

    International Nuclear Information System (INIS)

    The beam tail effect of multi-bunches will influence the electron beam performance in a high intensity thermionic RF gun. Beam dynamic calculations that illustrate the working states of single beam tail and multi-pulse feed-in of a performance-enhanced EC-ITC (external cathode independent tunable cavity) RF gun for an FEL (free electron laser) injector are performed to estimate the extracted bunch properties. By using both Parmela and homemade MATLAB codes, the effects of a single beam tail as well as interactions of multi-pulses are analyzed, where a ring-based electron algorithm is adopted to calculated RF fields and the space-charge field. Furthermore, the procedure of unexpected deviated-energy particles mixed with an effective bunch head is described by the MATLAB code as well. As a result, the performance-enhanced EC-ITC RF gun is proved to have the capability to extract continual stable bunches suitable for a high requirement THz-FEL. (authors)

  7. Reducing the Heat Load on the LCLS 120 Hz RF Gun with RF Pulse Shaping

    International Nuclear Information System (INIS)

    The LCLS injector must operate at 120 Hz repetition frequency but to date the maximum operating frequency of an S-band rf gun has been 50 Hz. The high fields desired for the LCLS gun operation limit the repetition frequency due to thermal expansion causing rf detuning and field redistribution. One method of addressing the thermal loading problem is too reduce the power lost on the cavity walls by properly shaping the rf pulse incident on the gun. The idea is to reach the steady state field value in the gun faster than the time constant of the gun would allow when using a flat incident rf pulse. By increasing the incident power by about a factor of three and then decreasing the incident power when the field reaches the desired value in the gun, the field build up time can be decreased by more than a factor of three. Using this technique the heat load is also decreased by more than a factor of three. In addition the rf coupling coefficient can be increased from the typical critically coupled designs to an overcoupled design which also helps reduce the field build up time. Increasing the coupling coefficient from 1 to 2 reduces the heat load by another 25% and still limits the reflected power and coupling hole size to manageable levels

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

    Science.gov (United States)

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

    1998-02-01

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

  9. Cavity design and beam simulations for the APS rf gun

    International Nuclear Information System (INIS)

    An earlier note discussed the preliminary design of the 1-1/2 cell RF cavity for the APS RF gun. This note describes the final design, including cavity properties and simulation results from the program rf gun. The basic idea for the new design was that the successful SSRL design could be improved upon by reducing fields that had nonlinear dependence on radius. As discussed previously, this would reduce the emittance and produce tighter momentum and time distributions. In addition, it was desirable to increase the fields in the first half-cell relative to the fields in the second half-cell, in order to allow more rapid initial acceleration, which would reduce the effects of space charge. Both of these goals were accomplished in the new design

  10. Physical design of FEL injector based on the performance-enhanced EC-ITC RF gun

    International Nuclear Information System (INIS)

    To meet the requirements of high performance THz-FEL (Free Electron Laser), a compact scheme of FEL injector was proposed. A thermionic cathode was chosen to emit electrons instead of a photo-cathode with its complex structure and high cost. The effective bunch charge was improved to ∼200 pC by adopting an enhanced EC-ITC (External Cathode Independently Tunable Cells) RF gun to extract micro-bunches; back bombardment effects were almost eliminated as well. Constant gradient accelerator structures were designed to improve energy to ∼14 MeV, while the focusing system was applied for emittance suppressing and bunch state maintenance. The physical design and beam dynamics of the key components for the FEL injector were analyzed. Furthermore, start-to-end simulations with multi-pulses were performed using homemade MATLAB and Parmela. The results show that continual high brightness electron bunches with a low energy spread and emittance could be obtained stably. (authors)

  11. Physical design of FEL injector based on performance-enhanced EC-ITC RF gun

    CERN Document Server

    Hu, Tong-ning; Pei, Yuan-ji; Li, Ji; Qin, Bin

    2013-01-01

    To meet requirements of high performance THz-FEL (Free Electron Laser), a compact scheme of FEL injector was proposed. Thermionic cathode was chosen to emit electrons instead of photo-cathode with complex structure and high cost. The effective bunch charge was improved to ~200pC by adopting enhanced EC-ITC (External Cathode Independently Tunable Cells) RF gun to extract micro-bunches, and back bombardment effects were almost eliminated as well. Constant gradient accelerator structures were designed to improve energy to ~14MeV, while focusing system was applied for emittance suppressing and bunch state maintenance. Physical design and beam dynamics of key components for FEL injector were analyzed. Furthermore, start-to-end simulations with multi-pulses were performed by using homemade MATLAB and Parmela. The results show that continual high brightness electron bunches with low energy spread and emittance could be obtained stably.

  12. Control led electron gun with a plasma cathode

    International Nuclear Information System (INIS)

    A description of a power electron gun with a plasma cathode is given. Its design is the development of gas-discharge sources of the duaplasmatron type. The basic elements of the gas-discharge source- the gun anode, the gun plasma cathode, the intermediate electrode of the source, and the tungsten thermocathode- are placed in side a high-voltage insulator. The diameter of the plasma cathode can be up to 2 cm, and the length of the accelerating gap- up to 0.3 cm. The discharge chamber is filled with Ar under 0.3 torr pressure. The electron beam focusing is carried out by means of two magnetic lenses, and displacement of the electron beam - by means of a deflecting coil. Experimental data are given on beam current control by modulating the discharge current and also by means of the electromagnetic system of the plasma gas-discharge source. The electron gun described shapes electron beams with a current up to 4.5 A under stationary operating conditions

  13. Development of an Energy Chirp Cell attached rf electron gun and its prospective applications

    International Nuclear Information System (INIS)

    We have been developing an Energy-Chirping-Cell attached rf electron gun (ECC rf gun) for ultra-short bunch generation with enough charge of more than 100 pC. ECC rf gun has an extra cell for energy chirping, then the energy chirped bunch is gradually compressed by the velocity bunching. We estimated the bunch length by coherent radiation spectrum that the bunch length will be less than 500 fs (rms). The important point of this rf gun is the gun itself has an abilities of acceleration and compression, thus ECC rf gun is the compact ultra-short electron source. Such a gun, we think, can be applied to a coherent THz source and dynamic electron diffraction microscope. In this presentation, the introduction of our ECC rf gun, recent experimental results, and future prospective applications will be discussed. (author)

  14. Performance of a first generation X-band photoelectron rf gun

    Science.gov (United States)

    Limborg-Deprey, C.; Adolphsen, C.; McCormick, D.; Dunning, M.; Jobe, K.; Li, H.; Raubenheimer, T.; Vrielink, A.; Vecchione, T.; Wang, F.; Weathersby, S.

    2016-05-01

    Building more compact accelerators to deliver high brightness electron beams for the generation of high flux, highly coherent radiation is a priority for the photon science community. A relatively straightforward reduction in footprint can be achieved by using high-gradient X-band (11.4 GHz) rf technology. To this end, an X-band injector consisting of a 5.5 cell rf gun and a 1-m long linac has been commissioned at SLAC. It delivers an 85 MeV electron beam with peak brightness somewhat better than that achieved in S-band photoinjectors, such as the one developed for the Linac Coherent Light Source (LCLS). The X-band rf gun operates with up to a 200 MV /m peak field on the cathode, and has been used to produce bunches of a few pC to 1.2 nC in charge. Notably, bunch lengths as short as 120 fs rms have been measured for charges of 5 pC (˜3 ×107 electrons), and normalized transverse emittances as small as 0.22 mm-mrad have been measured for this same charge level. Bunch lengths as short as 400 (250) fs rms have been achieved for electron bunches of 100 (20) pC with transverse normalized emittances of 0.7 (0.35) mm-mrad. We report on the performance and the lessons learned from the operation and optimization of this first generation X-band gun.

  15. Three Dimensional Effects on Virtual Cathode Formation in Electron Guns.

    Science.gov (United States)

    Valfells, Agust

    2001-10-01

    Recent experiments at the University of Maryland using photoemission from a dispenser cathode have yielded some interesting results regarding the effects of the area of emission and of the ratio between the pulse length and the gap transit time on the amount of current that may be drawn from an electron gun before a virtual cathode forms. The experiments show that a much higher current density may be drawn from a short pulse or limited emitter area than is anticipated by the Child-Langmuir limiting current. There is also evidence that the current may be increased even after virtual cathode formation, which leads one to distinguish between a limiting current density and a current density critical for virtual cathode formation. The experiments have also yielded some interesting results on the longitudinal structure of the current pulse passed through the anode. Some empirical and theoretical scaling laws regarding the formation of virtual cathodes in an electron gun will be presented. This work was motivated by the needs of the University of Maryland Electron Ring (UMER), where we wish to generate pulses that are well-localized in time and space.

  16. Cerenkov Radiator Driven by a Superconducting RF Electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Poole, B R; Harris, J R

    2011-03-07

    The Naval Postgraduate School (NPS), Niowave, Inc., and Boeing have recently demonstrated operation of the first superconducting RF electron gun based on a quarter wave resonator structure. In preliminary tests, this gun has produced 10 ps long bunches with charge in excess of 78 pC, and with beam energy up to 396 keV. Initial testing occurred at Niowave's Lansing, MI facility, but the gun and diagnostic beam line are planned for installation in California in the near future. The design of the diagnostic beam line is conducive to the addition of a Cerenkov radiator without interfering with other beam line operations. Design and simulations of a Cerenkov radiator, consisting of a dielectric lined waveguide will be presented. The dispersion relation for the structure is determined and the beam interaction is studied using numerical simulations. The characteristics of the microwave radiation produced in both the short and long bunch regimes will be presented.

  17. UV pulse shaping for the photocathode RF gun

    International Nuclear Information System (INIS)

    Recently, manipulation with the drive laser plays a significant role in high brightness electron beam production by the photocathode RF gun. The article takes efforts on the temporal shaping of the driving laser for the photocathode RF gun. Method based on pulse stacking by birefringent crystal of α-BBO serials was tried to directly shape ultraviolet laser pulse. Using four pieces of α-BBO crystals to separate an input UV pulse with appropriate duration into 16 sub-pulses can form a ps-spaced pulse train suitable for coherent THz production. The group delay dispersion induced by the crystals was also carefully considered. To avoid beam deterioration by long path propagation, imaging relay of the shaped pulse was applied.

  18. Upgrade of a Photocathode RF Gun at SPring-8

    CERN Document Server

    Taniuchi, Tsutomu; Dewa, Hideki; Hanaki, Hirofumi; Kobayashi, Toshiaki; Mizuno, Akihiko; Suzuki, Shinsuke; Tomizawa, Hiromitsu; Yanagida, Kenichi

    2004-01-01

    The test bench of a photocathode RF gun at SPring-8 has been upgraded. The radiation shielded area was expanded about 3 times larger and the maximum beam energy was increased from up to 30 MeV including a 3-m long accelerating tube. The clean room for the drive laser system was newly built and the performance and reliability of the laser was improved. After the construction of the shielded room and set up of the components, the RF conditioning of the waveguides, the gun cavity and the accelerating tube was successfully performed and the beam characteristics such as the emittance and bunch length were measured. In this presentation, further plans for the improvement of the beam quality will also be presented.

  19. UV pulse shaping for the photocathode RF gun

    Energy Technology Data Exchange (ETDEWEB)

    Yan Lixin, E-mail: yanlx@mail.tsinghua.edu.cn [Accelerator Laboratory, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense, Beijing 100084 (China); Du Qiang; Du Yingchao; Hua Jianfei; Huang Wenhui; Tang Chuanxiang [Accelerator Laboratory, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense, Beijing 100084 (China)

    2011-05-01

    Recently, manipulation with the drive laser plays a significant role in high brightness electron beam production by the photocathode RF gun. The article takes efforts on the temporal shaping of the driving laser for the photocathode RF gun. Method based on pulse stacking by birefringent crystal of {alpha}-BBO serials was tried to directly shape ultraviolet laser pulse. Using four pieces of {alpha}-BBO crystals to separate an input UV pulse with appropriate duration into 16 sub-pulses can form a ps-spaced pulse train suitable for coherent THz production. The group delay dispersion induced by the crystals was also carefully considered. To avoid beam deterioration by long path propagation, imaging relay of the shaped pulse was applied.

  20. Resonant Modes in a 1.6 Cells RF Gun

    Science.gov (United States)

    Ferrario, Massimo; Ronsivalle, Concetta

    2007-09-01

    The SPARC photoinjector RF gun consists in the BNL/SLAC/UCLA 1.6 cell structure designed to resonate at 2856 MHz in the π mode. It will be demonstrated by a numerical modelization based on SUPERFISH code combined with the LC-circuit analysis that the two oscillating modes of the system usually indicated as 0-mode and π-mode (the operating mode) are in reality a π/3-mode-like and a π-mode-like. The consequences on the definition of the coupling coefficient and on the use of mode-separation based RF measurements are described.

  1. Time dependant quantum efficiency and dark current measurements in an RF photocathode injector with a high quantum efficiency cathode

    International Nuclear Information System (INIS)

    Studies of photo-emission and field emission behavior in an RF gun have been carried out. Unexpected phenomena were observed. In situ changes in the cathode's quantum efficiency and dark current with time were seen during operation of the photo-injector. These changes were correlated with the magnetostatic field at the cathode. In addition, multipacting has been observed under certain conditions. Recent measurements indicate a correlation between multipacting and anomalous photo- and field emission behavior

  2. Generation of quasiequally spaced ultrashort microbunches in a photocathode rf gun

    International Nuclear Information System (INIS)

    A photocathode rf gun can generate trains of THz subpicosecond electron bunches by illuminating the cathode with trains of laser pulses, but it suffers from the increasing charge in the beam. The THz structure blurs and tends to disappear when the longitudinal space charge forces begin to play a significant role in the beam evolution. In this paper, we propose a scheme to restrain the space charge forces by expanding the transverse size of the laser pulses to reduce the charge density and adopting a multicell gun to increase the beam energy. Thus, quasiequally spaced ultrashort microbunches with relatively high charges can be generated according to our studies. Postacceleration can be used to freeze the longitudinal phase space dynamics. The proposed scheme is in principle able to generate intense multi-color narrow-band THz radiation and offers a promising way towards the tunable intense narrow-band THz sources

  3. Characteristics of test cavity for cryogenic photocathode RF-gun

    International Nuclear Information System (INIS)

    The cryogenic C-band photocathode RF-gun operating at 20 K is under development at LEBRA in Nihon University. The RF-gun is of the BNL-type 2.6-cell pillbox cavity with the resonant frequency of 5712 MHz. The 6N8 high purity OFC copper (corresponding to RRR-3000) is used as the cavity material. From the theoretical evaluation of the anomalous skin effect, the quality factor Q of the cavity at the operating temperature of 20K has been expected to be approximately 60000. Considering a low cooling capacity of the cryogenic system, initial operation of the RF gun is assumed at a duty factor of 0.01%. The cavity basic design and the beam bunching simulation were carried out using Poisson Superfish and General Particle Tracer (GPT). Machining and diffusion bonding of the cavity was carried out in KEK. The Q0 value of the π-mode resonance at the room temperature (23.5°C) deduced from the Smith chart was approximately 11440 after diffusion bonding. (author)

  4. Operation of the superconducting RF photo gun at ELBE

    CERN Document Server

    Teichert, J; Buettig, H; Janssen, D; Justus, M; Lehnert, U; Michel, P; Murcek, P; Schneider, Ch; Schurig, R; Staufenbiel, F; Xiang, R; Kamps, T; Rudolph, J; Schenk, M; Klemz, G; Will, I

    2012-01-01

    As the first superconducting RF photo-injector (SRF gun) in practical operation, the SRF gun has been successfully connected to the superconducting linac ELBE at Forschungzentrum Dresden-Rossendorf. The injection with this new gun will improve the beam quality for the users of the radiation source. The SRF gun contains a 3½ cell superconducting accelerating cavity with a frequency of 1.3 GHz. The design is for use of normal conducting photocathodes. At present, caesium telluride photocathodes are applied which are illuminated by an ultraviolet laser beam. The kinetic energy of the produced electron beam is 3 MeV which belongs to a peak electric field of 16 MV/m in the cavity. The maximum bunch charge which is obtained and measured in a Faraday cup is about 400 pC (20 μA average current at a repetition rate of 50 kHz). The SRF gun injector is connected to the ELBE accelerator via a dogleg with two 45° deflection magnets. This connection beam line was commissioned in January 2010. A first beam injection into...

  5. Operation of the superconducting RF photo gun at ELBE

    CERN Document Server

    Teichert, J; Buettig, H; Janssen, D; Justus, M; Lehnert, U; Michel, P; Murcek, P; Schneider, C; Schurig, R; Staufenbiel, F; Xiang, R; Kamps, T; Rudolph, J; Schenk, M; Klemz, G; Will, I

    2011-01-01

    As the first superconducting RF photo-injector (SRF gun) in practical operation, the SRF gun has been successfully connected to the superconducting linac ELBE at Forschungzentrum Dresden-Rossendorf. The injection with this new gun will improve the beam quality for the users of the radiation source. The SRF gun contains a 3½ cell superconducting accelerating cavity with a frequency of 1.3 GHz. The design is for use of normal conducting photocathodes. At present, caesium telluride photocathodes are applied which are illuminated by an ultraviolet laser beam. The kinetic energy of the produced electron beam is 3 MeV which belongs to a peak electric field of 16 MV/m in the cavity. The maximum bunch charge which is obtained and measured in a Faraday cup is about 400 pC (20 µA average current at a repetition rate of 50 kHz). The SRF gun injector is connected to the ELBE accelerator via a dogleg with two 45° deflection magnets. This connection beam line was commissioned in January 2010. A first beam injection into...

  6. 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...

  7. Investigating the effect of electron emission pattern on RF gun beam quality

    Science.gov (United States)

    Rajabi, A.; Shokri, B.

    2016-05-01

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect.

  8. Development of superconducting RF electron gun in KEK

    International Nuclear Information System (INIS)

    A high-intensity electron gun is required for the next generation ERL or a high power FEL system. KEK started development of a superconducting RF electron gun in addition to the conventional DC electron gun. 1.3 GHz of the resonant frequency, 100 mA of the beam current, and 2 MeV of the energy in the exit of gun are made into the precondition. By combining electromagnetic field analysis and charged particle dynamics analysis, the optimal design of the cavity shape, where the maximum surface electric field of less than 50 MV/m, a low emittance of less than 1 mm mrad, and a low energy spread of less than 0.1% (2 keV)) can be filled with this precondition, was tried. The designed elliptical cavity is a 1.5-cell structure made of Nb material, and the three half cells are manufactured from one common die. Thermo-structural analysis under cryogenic temperature and vacuum environment was also carried out, and the resonance frequency change would be evaluated. (author)

  9. Laser system upgrade for RF gun at SuperKEKB

    International Nuclear Information System (INIS)

    For injector linac of SuperKEKB project, the electron beams with a charge of 5 nC and a normalized emittance of 10 μm are expected to be generated in the photocathode RF gun. An ytterbium (Yb) based laser source with a center wavelength of 258 nm and a pulse width of 30 ps is employed to obtain high peak energy pulses. More than 5 nC electron with single-bunch has so far been generated in the 2 Hz. Next, the laser system was restructured to 25 Hz double-bunch, and 1.3 nC electron beams was obtained at both bunches. (author)

  10. 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.

  11. Slice emittance measurement for photocathode RF gun with solenoid scanning and RF deflecting cavity

    Science.gov (United States)

    Li, Chen; Huang, WenHui; Du, YingChao; Yan, LiXin; Tang, ChuanXiang

    2011-12-01

    The radiation of high-gain short-wavelength free-electron laser depends on the slice transverse emittance of the electron bunch. This essay introduces the method of slice emittance measurement, and shows the brief setup of this experiment using the solenoid scanning and RF deflecting cavity at Tsinghua University. The preliminary experimental results show that the slice rms emittance of the electron bunch generated by photocathode RF gun has considerable variations along the bunch and is typically less than 0.55 mm mrad for the laser rms radius of 0.4 mm.

  12. Development of photocathode rf electron gun for ultra-short bunch generation

    International Nuclear Information System (INIS)

    We have been developing an S-band photocathode rf electron gun at Waseda University. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell (ECC). To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracing by GPT/PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch and it can be compressed by the velocity bunching through the 2.3m drift space down to 100fsec. This cavity was already manufactured on the collaboration with KEK. In this conference, the design of ECC-RF-Gun, the results of low level test and plan of beam test will be presented. (author)

  13. Cathodic arc grown niobium films for RF superconducting cavity applications

    Science.gov (United States)

    Catani, L.; Cianchi, A.; Lorkiewicz, J.; Tazzari, S.; Langner, J.; Strzyzewski, P.; Sadowski, M.; Andreone, A.; Cifariello, G.; Di Gennaro, E.; Lamura, G.; Russo, R.

    2006-07-01

    Experimental results on the characterization of the linear and non-linear microwave properties of niobium film produced by UHV cathodic arc deposition are presented. Surface impedance Zs as a function of RF field and intermodulation distortion (IMD) measurement have been carried out by using a dielectrically loaded resonant cavity operating at 7 GHz. The experimental data show that these samples have a lower level of intrinsic non-linearities at low temperature and low circulating power in comparison with Nb samples grown by sputtering. These results make UHV cathodic arc deposition a promising technique for the improvement of RF superconducting cavities for particle accelerators.

  14. Cathodic arc grown niobium films for RF superconducting cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Catani, L. [INFN-Roma2, Rome (Italy); Cianchi, A. [INFN-Roma2, Rome (Italy); Lorkiewicz, J. [INFN-Roma2, Rome (Italy); Tazzari, S. [Universita di Roma ' Tor Vergata' and INFN-Roma2, Rome (Italy); Langner, J. [Soltan Institute for Nuclear Studies, Swierk (Poland); Strzyzewski, P. [Soltan Institute for Nuclear Studies, Swierk (Poland); Sadowski, M. [Soltan Institute for Nuclear Studies, Swierk (Poland); Andreone, A. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Cifariello, G. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Di Gennaro, E. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Lamura, G. [University of Napoli ' Federico II' and INFN-NA, Naples (Italy); Russo, R. [Seconda Universita di Napoli, INFN-NA, Naples (Italy)

    2006-07-15

    Experimental results on the characterization of the linear and non-linear microwave properties of niobium film produced by UHV cathodic arc deposition are presented. Surface impedance Z {sub s} as a function of RF field and intermodulation distortion (IMD) measurement have been carried out by using a dielectrically loaded resonant cavity operating at 7 GHz. The experimental data show that these samples have a lower level of intrinsic non-linearities at low temperature and low circulating power in comparison with Nb samples grown by sputtering. These results make UHV cathodic arc deposition a promising technique for the improvement of RF superconducting cavities for particle accelerators.

  15. Repetitive Bunches from RF-Photo Gun Radiate Coherently

    CERN Document Server

    Van der Geer, C A J; Van der Geer, S B

    2004-01-01

    We consider to feed the laser wake field accelerator of the alpha-X project by a train of low charge pancake electron bunches to reduce undesired expansion due to space-charge forces. To this purpose the photo excitation laser of the rf-injector is split into a train of sub-pulses, such that each of the produced electron bunches falls into a successive ponderomotive well of the plasma accelerator. This way the total accelerated charge is not reduced. The repetitive photo gun can be tested, at low energy, by connecting it directly to the undulator and monitoring the radiation. The assertions are based on the results of new GPT simulations.

  16. Note: Design and development of improved indirectly heated cathode based strip electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Namita; Patil, D. S.; Dasgupta, K. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Bade, Abhijeet; Tembhare, G. U. [Department of Mechanical Engineering, Veermata Jijabai Technological Institute, Matunga, Mumbai 400 019 (India)

    2015-02-15

    An improved design of indirectly heated solid cathode based electron gun (200 kW, 45 kV, 270° bent strip type electron gun) has been presented. The solid cathode is made of thoriated tungsten, which acts as an improved source of electron at lower temperature. So, high power operation is possible without affecting structural integrity of the electron gun. The design issues are addressed based on the uniformity of temperature on the solid cathode and the single long filament based design. The design approach consists of simulation followed by extensive experimentation. In the design, the effort has been put to tailor the non-uniformity of the heat flux from the filament to the solid cathode to obtain better uniformity of temperature on the solid cathode. Trial beam experiments have been carried out and it is seen that the modified design achieves one to one correspondence of the solid cathode length and the electron beam length.

  17. Note: Design and development of improved indirectly heated cathode based strip electron gun

    International Nuclear Information System (INIS)

    An improved design of indirectly heated solid cathode based electron gun (200 kW, 45 kV, 270° bent strip type electron gun) has been presented. The solid cathode is made of thoriated tungsten, which acts as an improved source of electron at lower temperature. So, high power operation is possible without affecting structural integrity of the electron gun. The design issues are addressed based on the uniformity of temperature on the solid cathode and the single long filament based design. The design approach consists of simulation followed by extensive experimentation. In the design, the effort has been put to tailor the non-uniformity of the heat flux from the filament to the solid cathode to obtain better uniformity of temperature on the solid cathode. Trial beam experiments have been carried out and it is seen that the modified design achieves one to one correspondence of the solid cathode length and the electron beam length

  18. Simulations of multipacting in the cathode stalk and FPC of 112 MHz 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.

    2012-05-20

    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 used for testing of the performance of various high quantum efficiency photocathodes. In a previous paper, we presented the design of the cathode stalks and a Fundamental Power Coupler (FPC). In this paper we present updated designs of the cathode stalk and FPC. Multipacting in the cathode stalk and FPC was simulated using three different codes. All simulation results show no serious multipacting in the cathode stalk and FPC.

  19. A prediction-based self-adaptive feed-forward control system for thermionic cathode microwave electron gun

    International Nuclear Information System (INIS)

    Beijing Free Electron Laser Facility (BFEL) adopts a thermionic cathode microwave electron gun as its RF linac injector. For relatively long macro-pulse operation, the back-bombardment effect deteriorates the characteristics of the accelerated electron beam. So the authors developed a prediction-based self-adaptive feed-forward control system to compensate for the beam-loading. The system is operational and some experimental results have been obtained, which suggests that the system is effective to improve the beam quality, and that it's capable of dealing with complicated systems whose response is time-variable, non-linear and of long delay

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

    International Nuclear Information System (INIS)

    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)

  1. 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.

  2. Development of a 3.5 cell S-band photocathode RF electron gun

    International Nuclear Information System (INIS)

    We have been developing a photocathode rf electron gun. Last year, we succeeded in operating a new design 1.6 cell rf gun cavity with large mode separation of 8.6 MHz. Encouraging by this success, we designed a 3.5 cell rf gun cavity and start manufacturing. It will produce a high quality electron beam with energy of more than 10 MeV. In order to optimize the operating conditions, we performed beam tracing simulation studies using SUPERFISH and PARMELA. The design of 3.5 cell rf gun cavity, results of simulation studies and current status of 3.5 cell cavity manufacturing will be presented at the conference. (author)

  3. Study on energy difference compensation for high intense multi-bunch electron beam generated by a photocathode RF-gun

    International Nuclear Information System (INIS)

    At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it has to be considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the bunch by bunch energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1% p-p, while 5% p-p without compensation. In this conference, we will report our multi-bunch electron beam linac system, the details of energy compensation method using the RF amplitude modulation and the results of beam experiment. (author)

  4. Amorphous superficial generation by means of a cool cathode electronic gun

    International Nuclear Information System (INIS)

    An electron gun based on a low pressure gaseous discharge for the generation of amorphous surfaces was used. Such gun, similar to those employed for gaseous laser excitation experiments consisted of a cool cathode of 7.5 cm of diameter, which delivered a current up to 100 Angstrom to 40kV, storing energy densities up to 200J/cm2 on the samples by pulses from 10 μs to 30 μs. The system permits to control not only the tension but the gun current as well as to vary the focus changing the cathode'distance to the target. (Author)

  5. 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...

  6. Improved cathode assembly for electron gun of 7 MeV linac

    International Nuclear Information System (INIS)

    This Electron Beam Linear Accelerator (LINAC) of RPCD, BARC is the key component of the pulse radiolysis facility being used for radiation chemistry research. The heart of the LINAC is the electron gun, which generates electron from a tungsten cathode. Recently an improved cathode assembly is designed and fabricated for better performance of the linac. (author)

  7. Development of Electron Guns for Linacs and DC Accelerator

    International Nuclear Information System (INIS)

    Electrons guns for RF linacs and DC Accelerators are designed and developed at Electron Beam Centre (EBC)/APPD/BARC. Planar geometry grid and Pierce geometry grid configuration diode and triode guns with LaB6 cathode are developed. The cathode assembly consists of cups and heat shields made out of Tantalum and Rhenium sheets. The cathode assembly and the electron guns are tested on a test bench for beam characterization. The paper presents the development of the electron guns.

  8. RF Simulation of the 187 MHz CW Photo-RF Gun Cavity at LBNL

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Tong-Ming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2008-12-01

    A 187 MHz normal conducting Photo-RF gun cavity is designed for the next generation light sources. The cavity is capable of operating in CW mode. As high as 750 kV gap voltage can be achieved with a 20 MV/m acceleration gradient. The original cavity optimization is conducted using Superfish code (2D) by Staples. 104 vacuum pumping slots are added and evenly spaced over the cavity equator in order to achieve better than 10-10-Tor of vacuum. Two loop couplers will be used to feed RF power into the cavity. 3D simulations are necessary to study effects from the vacuum pumping slots, couplers and possible multipactoring. The cavity geometry is optimized to minimize the power density and avoid multipactoring at operating field level. The vacuum slot dimensions are carefully chosen in consideration of both the vacuum conduction, local power density enhancement and the power attenuation at the getter pumps. This technical note gives a summary of 3D RF simulation results, multipactoring simulations (2D) and preliminary electromagnetic-thermal analysis using ANSYS code.

  9. Development of spark cathode electron guns for the CO2 laser fusion program. Final report, July 1978-December 1979

    International Nuclear Information System (INIS)

    Spark cathodes are designed and constructed to replace the bladed cold cathode structure in the electron guns of the Los Alamos Scientific Laboratory, Antares, prototype power amplifier and driver amplifier. Design work is described and data from cathode testing is reported. The spark cathode offers precise control of emission site location, design flexibility, and high reliability

  10. Brazing of photocathode RF gun structures in Hydrogen atmosphere: Process qualification, effect of brazing on RF properties and vacuum compatibility

    International Nuclear Information System (INIS)

    In this paper, we report on the development of a brazing process for an ultra-high vacuum (UHV) compatible photocathode RF gun structure developed at our Centre. The choice of brazing alloy and its form, brazing clearance between parts to be joined and the brazing cycle adopted have been qualified through metallographic examination of identical joints on an OFE copper prototype that was cut open after brazing. The quality of brazed joint not only affects the UHV compatibility of the gun, but also influences the RF parameters finally achieved. A 2-D electromagnetic code, SUPERFISH, was used to predict the variation in RF parameters before and after brazing considering actual brazing clearances provided between the parts to be joined. Results obtained from low power RF measurements on the brazed gun structure confirm the integrity of the brazed joints and show good agreement with those predicted by electromagnetic simulations. The brazed gun structure has been leak-tested and pumped down to a vacuum level limited by the vacuum compatibility of the flange-fittings employed in the setup.

  11. Brazing of photocathode RF gun structures in Hydrogen atmosphere: Process qualification, effect of brazing on RF properties and vacuum compatibility

    Science.gov (United States)

    Kak, Ajay; Kulshreshtha, P.; Lal, Shankar; Kaul, Rakesh; Ganesh, P.; Pant, K. K.; Abhinandan, Lala

    2012-11-01

    In this paper, we report on the development of a brazing process for an ultra-high vacuum (UHV) compatible photocathode RF gun structure developed at our Centre. The choice of brazing alloy and its form, brazing clearance between parts to be joined and the brazing cycle adopted have been qualified through metallographic examination of identical joints on an OFE copper prototype that was cut open after brazing. The quality of brazed joint not only affects the UHV compatibility of the gun, but also influences the RF parameters finally achieved. A 2-D electromagnetic code, SUPERFISH, was used to predict the variation in RF parameters before and after brazing considering actual brazing clearances provided between the parts to be joined. Results obtained from low power RF measurements on the brazed gun structure confirm the integrity of the brazed joints and show good agreement with those predicted by electromagnetic simulations. The brazed gun structure has been leak-tested and pumped down to a vacuum level limited by the vacuum compatibility of the flange-fittings employed in the setup.

  12. Development of rf electron gun with energy chirp cell for ultra-short bunch generation

    International Nuclear Information System (INIS)

    We have been developing an S-band photocathode rf electron gun at Waseda University. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell. To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracing by PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch. The front electron have lower energy than rear. Then transporting about 2m, the bunch can be compressed down to 200fsec electron bunch with the charge of 100pC. This ultrashort bunch will be able to use for generating CSR THz radiation, pumping some material to be studied by pulse radiolysis method, and so on. In this conference, the design of chirping cell attached rf-gun, the results of tracing simulation and plan of manufacturing will be presented. (author)

  13. High current density electron gun with a LaB6 thermionic cathode

    International Nuclear Information System (INIS)

    To develop a high current electron gun for the induction linac, a small prototype of a Pierce-type electron gun using a planar 12 mm-diameter lanthanum hexaboride as an electron emitter has been made. The basic properties of the gun are under investigation and preliminary results are presented. The gun has been operated up to 21kV, obtaining current of 5.5A with 250 nsec width at 1,650degC in the space-charge-limited region. The cathode is heated by electron bombardment and radiation from a tungsten heater. The maximum temperature of the cathode reaches 1,690degC when the total heating power comes up to 590W. (author)

  14. An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

    Energy Technology Data Exchange (ETDEWEB)

    Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha, E-mail: schaefer@ph4.physik.uni-goettingen.de; Ropers, Claus, E-mail: cropers@gwdg.de [4th Physical Institute, Solids and Nanostructures, University of Göttingen, Göttingen 37077 (Germany)

    2015-11-07

    We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy.

  15. An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

    International Nuclear Information System (INIS)

    We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy

  16. A low emittance DC electron gun using single crystal cathode of LaB6

    International Nuclear Information System (INIS)

    Development of an electron gun capable of producing low emittance is in the interests of further applications of light brightness electron beam. A prominent point of this DC gun is that operation high voltage is very low because of the small size of cathode and a short distance between the cathode and the anode. A pulsed high voltage of 50 kV is supplied, and pulse duration is variable from 1 to 5 μsec. The design details and present status are reported. (author)

  17. 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.

  18. Yb hybrid laser system of DAW RF gun for SuperKEKB

    International Nuclear Information System (INIS)

    SuperKEKB is a planned upgrade to the KEKB accelerator with higher luminosity. Corresponding to the reduction of dynamic aperture and beam life, the photocathode DAW-type RF gun for high-current, low-emittance beams will be employed in the injector linac. The electron beams with a charge of 5 nC and a normalized emittance of 10 μm are expected to be generated in the RF gun by using the laser source at A-1 unit. Introducing the Ytterbium (Yb) hybrid laser system that includes Yb-doped fiber and Yb:YAG solid system, generates mJ pulses with a center wavelength of 258 nm and a pulse width of 30 ps. 1.0 nC beam generation from the RF gun was achieved. (author)

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

    International Nuclear Information System (INIS)

    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)

  20. Theoretical research on electron beam modulation in a field-emission cold cathode electron gun

    International Nuclear Information System (INIS)

    In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field-emission (FE) electron gun based on carbon nanotubes is researched. By feeding a high-frequency field between the cathode and the anode, the steady FE electron beam can be modulated in the electron gun. The optimal structure of the electron gun is discovered using 3D electromagnetism simulation software, and the FE electron gun is simulated by PIC simulation software. The results show that a broadband (74–114 GHz) modulation can be achieved by the electron gun with a rhombus channel, and the modulation amplitude of the beam current increases with the increases in the input power and the electrostatic field

  1. 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...

  2. BXERL photo-injector based on a 217 MHz normal conducting RF gun

    Institute of Scientific and Technical Information of China (English)

    LIU Sheng-Guang; HUANG Tong-Ming; XU Jin-Qiang

    2011-01-01

    The Beijing X-ray Energy Recovery Linac(BXERL)test facility is proposed in Institute of High Physics(IHEP).In this proposal,the main linac requires the injector to provide an electron beam with 5 MeV energy and 10 mA average current.An injector based on DC gun technology is the first candidate electron source for BXERL.However,the field emission in the DC gun cavity makes it much more difficult to increase the high voltage to more than 500 kV.Another technology based on a 217 MHz normal conducting RF gun is proposed as the backup injector for this test facility.We have designed this RF gun with 2D SUPERFISH code and 3D MICROWAVE STUDIO code.In this paper,we present the optimized design of the gun cavity,the gun RF parameters and the set-up of the whole injector system.The detailed beam dynamics have been done and the simulation results show that the injector can generate electron bunches with RMS normalizedemittance 1.0 πmm.mrad,bunch length 0.77 mm,beam energy 5.0 MeV and energy spread 0.60%.

  3. BXERL photo-injector based on a 217 MHz normal conducting RF gun

    Science.gov (United States)

    Liu, Sheng-Guang; Huang, Tong-Ming; Xu, Jin-Qiang

    2011-09-01

    The Beijing X-ray Energy Recovery Linac (BXERL) test facility is proposed in Institute of High Physics (IHEP). In this proposal, the main linac requires the injector to provide an electron beam with 5 MeV energy and 10 mA average current. An injector based on DC gun technology is the first candidate electron source for BXERL. However, the field emission in the DC gun cavity makes it much more difficult to increase the high voltage to more than 500 kV. Another technology based on a 217 MHz normal conducting RF gun is proposed as the backup injector for this test facility. We have designed this RF gun with 2D SUPERFISH code and 3D MICROWAVE STUDIO code. In this paper, we present the optimized design of the gun cavity, the gun RF parameters and the set-up of the whole injector system. The detailed beam dynamics have been done and the simulation results show that the injector can generate electron bunches with RMS normalized emittance 1.0 πmm·mrad, bunch length 0.77 mm, beam energy 5.0 MeV and energy spread 0.60%.

  4. Optimizing RF gun cavity geometry within an automated injector design system

    Energy Technology Data Exchange (ETDEWEB)

    Alicia Hofler ,Pavel Evtushenko

    2011-03-28

    RF guns play an integral role in the success of several light sources around the world, and properly designed and optimized cw superconducting RF (SRF) guns can provide a path to higher average brightness. As the need for these guns grows, it is important to have automated optimization software tools that vary the geometry of the gun cavity as part of the injector design process. This will allow designers to improve existing designs for present installations, extend the utility of these guns to other applications, and develop new designs. An evolutionary algorithm (EA) based system can provide this capability because EAs can search in parallel a large parameter space (often non-linear) and in a relatively short time identify promising regions of the space for more careful consideration. The injector designer can then evaluate more cavity design parameters during the injector optimization process against the beam performance requirements of the injector. This paper will describe an extension to the APISA software that allows the cavity geometry to be modified as part of the injector optimization and provide examples of its application to existing RF and SRF gun designs.

  5. The elbe accelerator facility starts operation with the superconducting rf gun

    CERN Document Server

    Xiang, R; Buettig, H; Janssen, D; Justus, M; Lehnert, U; Michel, P; Murcek, P; Schneider, C; Schurig, R; Staufenbiel, F; Teichert, J; Kamps, T; Rudolph, J; Schenk, M; Klemz, G; Will, I

    2010-01-01

    As the first superconducting rf photo-injector (SRF gun) in practice, the FZD 3+1/2 cell SRF gun is successfully connected to the superconducting linac ELBE. This setting will improve the beam quality for ELBE users. It is the first example for an accelerator facility fully based on superconducting RF technology. For high average power FEL and ERL sources, the combination of SRF linac and SRF gun provides a new chance to produce beams of high average current and low emittance with relative low power consumption. The main parameters achieved from the present SRF gun are the final electron energy of 3 MeV, 16 μA average current, and rms transverse normalized emittances of 3 mm mrad at 77 pC bunch charge. A modified 3+1/2 cell niobium cavity has been fabricated and tested, which will increase the rf gradient in the gun and thus better the beam parameters further. In this paper the status of the integration of the SRF gun with the ELBE linac will be presented, and the latest results of the beam experiments will ...

  6. Design and beam dynamics simulations of an S-band photocathode rf gun

    Science.gov (United States)

    Kumar, Arvind; Pant, K. K.; Krishnagopal, S.

    2002-10-01

    We are building an S-band photocathode rf gun as an injector to a 30MeV electron linac for FEL applications. Here we discuss details of design simulations performed using superfish and gdfidl and compare with results of cold tests performed on prototype cells of the photocathode rf gun. We also discuss beam dynamics simulations performed using parmela and report results from simulations to achieve a normalized transverse rms emittance of about 1π mm mrad for a 10ps pulse with 1nC charge in the presence of a solenoid magnetic field used for emittance compensation.

  7. Compact narrow-band THz radiation source based on photocathode rf gun

    International Nuclear Information System (INIS)

    Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800 pC) can be generated directly in the photocathode rf gun. According to the analytical and simulated results, a narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m). (authors)

  8. 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.

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

    International Nuclear Information System (INIS)

    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

  10. Running experience with the laser system for the RF gun based injector at the TESLA Test Facility linac

    International Nuclear Information System (INIS)

    During the run 1998/1999, the new injector based on a laser driven RF gun was brought into operation at the TESLA Test Facility Linac (TTFL) at DESY. A key element of the injector is the laser system to illuminate the RF gun cathode to produce short (ps) electron bunches of high charge (nC). This electron beam is used to perform various experiments for the future TESLA linear collider, and to drive the free electron laser TTF-FEL. The laser design is challenged by the unusual requirement of providing synchronized ps UV pulses in 0.8 ms long trains with ambitious stability requirements. The design was also driven by the requirement to have an operational system with a high reliability. The system is based on a mode locked solid-state (Nd:YLF) pulse train oscillator followed by a linear amplifier chain. In a first phase, a laser pulse rate of 1 MHz within the train has been realized, 2.25 MHz and 9 are in preparation. Performance and running experiences with the laser system during the last TTF run are reported

  11. Development of an S-band multi-cell accelerating cavity for rf gun and booster linac

    International Nuclear Information System (INIS)

    We have been developing a photocathode rf gun. The rf gun with multi cell can produce a high energy electron beam, so it may be used for numerous applications such as medicine and industry. At Laser Undulator Compact X-ray source (LUCX), we have developed a compact X-ray source based on inverse Compton scattering. An S-band 3.5 cell rf electron gun which is 20 cm long can produce a high quality electron beam with energy of more than 10 MeV. According to the simulation, the emittance of 3.5 cell rf gun is as low as that of 1.6 cell rf gun. The electromagnetic design has been performed by the code SUPERFISH, and the particle tracing by PARMELA. The new rf gun is already installed and produced a high quality electron beam with energy of 8.7 MeV. As a consequence of the substantial efforts of developing rf cavity, we decide to make a compact RF accelerating structure with more cell for achieving a smaller system. The measurement results of using the 3.5 cell rf gun, the design of 12 cell booster cavity, and current status of 12 cell cavity manufacturing will be presented at the conference. (author)

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

    International Nuclear Information System (INIS)

    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.

  13. Design and construction a full copper photocathode RF gun

    International Nuclear Information System (INIS)

    The design and construction of an all copper S-band one-and-half cell photocathode electron gun without a choke joint is described. The methods utilized to determine the field balance at the operational frequency without usage of the bead pulling perturbation measurement is given together wit the computational data

  14. 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.

  15. The operation of the BNL/ATF gun-IV photocathode RF gun at the Advanced Photon Source

    International Nuclear Information System (INIS)

    At the Advanced Photon Source (APS) at Argonne National Laboratory (ANL), a free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) process is nearing completion. Recently, an rf photoinjector gun system was made available to the APS by Brookhaven National Laboratory/Accelerator Test Facility (BNL/ATF). It will be used to provide the high-brightness, low-emittance, and low-energy spread electron beam required by the SASE FEL theory. A Nd:Glass laser system, capable of producing a maximum of 500 microJ of UV in a 1-10 ps pulse at up to a 10-Hz repetition rate, serves as the photoinjector's drive laser. Here, the design, commissioning, and integration of this gun with the APS is discussed

  16. Simulation study on ultrashort pulse electron generation in laser photocathode RF gun linac

    International Nuclear Information System (INIS)

    A new S-band femtosecond electron linear accelerator, which was constructed with a laser driven photocathode RF gun, a linear accelerator (linac) and a magnetic pulse compressor, was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions in femtosecond time regions. In order to generate the ultrashort pulse electrons, we simulated the electron generation in the RF gun with a picosecond Nd: YLF laser light by PARMELA code with space-charge effects. The energy modulation of the electron pulse in the linac was also calculated with the optimum of the RF phase. The pulse compression in the magnetic pulse compressor was simulated by Trace-3D code. A few tens femtosecond electron pulse was obtained by optimizing the magnetic fields in the magnetic pulse compressor. (author)

  17. R and D of the gun cathode for the SPring-8 linac

    International Nuclear Information System (INIS)

    The SPring-8 linac has used Y-845 cathodes (Eimac/CPI) as an electron gun cathode. However, its cathode emission current is not sufficient in some cases. We therefor started the development of a new type cathode for reinforcement of the emission current and for reduction of the grid emission current which increases along with the heater-on time. The target in terms of the cathode emission is to double that of Y-845. To produce a solid and reliable cathode, a thin metal plate with honeycomb etched holes was adopted as a grid mesh instead of a traditional wire mesh. Because the aperture ratio of such an etched plate is lower than that of a wire mesh, we decided to employ the cathode disk which has honeycomb micro dimples on its surface forming focused multi electron beams with the aligned grid plate to result in a very high beam transmission rate. The first test of the cathode assembly, whose cathode disk has the micro-dimple array structure, presented that the emission of 13 A was obtained. The detail of the development and the first test will be reported in this paper. (author)

  18. Measurement and control of field in RF GUN at FLASH

    Science.gov (United States)

    Brandt, A.; Hoffmann, M.; Koprek, W.; Pucyk, P.; Simrock, S.; Pozniak, K. T.; Romaniuk, R. S.

    2008-01-01

    The paper describes the hardware and software architecture of a control and measurement system for electromagnetic field stabilization inside the radio frequency electron gun, in FLASH experiment. A complete measurement path has been presented, including I and Q detectors and FPGA based, low latency digital controller. Algorithms used to stabilize the electromagnetic field have been presented as well as the software environment used to provide remote access to the control device. An input signal calibration procedure has been described as a crucial element of measurement process.

  19. Emittance Measurement with Upgraded RF Gun System at SPring-8

    CERN Document Server

    Mizuno, Akihiko; Hanaki, Hirofumi; Taniuchi, Tsutomu; Tomizawa, Hiromitsu; Uesaka, Mitsuru

    2005-01-01

    A single cell S-band RFgun has been developed at the SPring-8 since 1996. The minimum normalized beam emittance, measured with double slits' scanning method in 2002, was 2.3 pi mm mrad at the exit of the gun cavity with charge of 0.1 nC/bunch. In 2004, we installed a following accelerator structure to investigate beam behavior of the whole injector system. In this paper, we report emittance measurement results of upgraded system, using variable quadrupole magnet method. The minimum emittance of 2.0 pi mm mrad with a net charge of 0.14 nC/bunch were able to be measured.

  20. Generation and measurement of sub-picosecond electron bunch in photocathode rf gun

    International Nuclear Information System (INIS)

    We consider a scheme to generate a sub-picosecond electron bunch in the photocathode rf gun by improving the acceleration gradient in the gun, suitably tuning the bunch charge, the laser spot size and the acceleration phase, and reducing the growth of transverse emittance by laser shaping. A nondestructive technique is also reported to measure the electron bunch length, by measuring the high-frequency spectrum of wakefield radiation which is caused by the passage of a relativistic electron bunch through a channel surrounded by a dielectric. (authors)

  1. 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.

  2. New cathode-ray tube (CRT) gun interconnection assembly

    Science.gov (United States)

    McCormick, David M.

    1992-07-01

    A novel interconnection assembly method was developed for the electron gun of airborne CRTs, which makes it possible for the connectors to be connected and disconnected repeatedly (as opposed to soldering as in the conventional method) to provide access to the tube and its interconnecting cable harness. Environmental tests were conducted on one series of CRTs, which included electrical and environmental conditions which would be experienced in a worst-case aircraft cabin environment, including the altitude, humidity, thermal shock, vibration, and mechanical shock.

  3. Effects of pulse-length and emitter area on virtual cathode formation in electron guns

    Science.gov (United States)

    Valfells, Ágúst; Feldman, D. W.; Virgo, M.; O'Shea, P. G.; Lau, Y. Y.

    2002-05-01

    Recent experiments at the University of Maryland using photoemission from a dispenser cathode have yielded some interesting results regarding the effects of the area of emission and of the ratio between the pulse length and the gap transit time on the amount of current that may be drawn from an electron gun before a virtual cathode forms. The experiments show that a much higher current density may be drawn from a short pulse or limited emitter area than is anticipated by the Child-Langmuir limiting current. There is also evidence that the current may be increased even after virtual cathode formation, which leads a distinction between a limiting current density and a current density critical for virtual cathode formation. The experiments have also yielded some interesting results on the longitudinal structure of the current pulse passed through the anode. Some empirical and theoretical scaling laws regarding the formation of virtual cathodes in an electron gun will be presented. This work was motivated by the needs of the University of Maryland Electron Ring (UMER) [P. G. O'Shea, M. Reiser, R. A. Kishek et al., Nucl. Instrum. Methods Phys. Res. A 464, 646 (2001)] where the goal is to generate pulses that are well-localized in time and space.

  4. Effects of pulse-length and emitter area on virtual cathode formation in electron guns

    International Nuclear Information System (INIS)

    Recent experiments at the University of Maryland using photoemission from a dispenser cathode have yielded some interesting results regarding the effects of the area of emission and of the ratio between the pulse length and the gap transit time on the amount of current that may be drawn from an electron gun before a virtual cathode forms. The experiments show that a much higher current density may be drawn from a short pulse or limited emitter area than is anticipated by the Child-Langmuir limiting current. There is also evidence that the current may be increased even after virtual cathode formation, which leads a distinction between a limiting current density and a current density critical for virtual cathode formation. The experiments have also yielded some interesting results on the longitudinal structure of the current pulse passed through the anode. Some empirical and theoretical scaling laws regarding the formation of virtual cathodes in an electron gun will be presented. This work was motivated by the needs of the University of Maryland Electron Ring (UMER) [P. G. O'Shea, M. Reiser, R. A. Kishek et al., Nucl. Instrum. Methods Phys. Res. A 464, 646 (2001)] where the goal is to generate pulses that are well-localized in time and space

  5. Effect of RF Gradient upon the Performance of the Wisconsin SRF Electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Bosch, Robert [SRC U. Wisconsin-Madison; Legg, Robert A. [JLAB

    2013-12-01

    The performance of the Wisconsin 200-MHz SRF electron gun is simulated for several values of the RF gradient. Bunches with charge of 200 pC are modeled for the case where emittance compensation is completed during post-acceleration to 85 MeV in a TESLA module. We first perform simulations in which the initial bunch radius is optimal for the design gradient of 41 MV/m. We then optimize the radius as a function of RF gradient to improve the performance for low gradients.

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

    International Nuclear Information System (INIS)

    The Electron Beam Controlled Discharge CO2 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 cm2 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

  7. Initial experimental results of a machine learning-based temperature control system for an RF gun

    CERN Document Server

    Edelen, A L; Milton, S V; Chase, B E; Crawford, D J; Eddy, N; Edstrom, D; Harms, E R; Ruan, J; Santucci, J K; Stabile, P

    2015-01-01

    Colorado State University (CSU) and Fermi National Accelerator Laboratory (Fermilab) have been developing a control system to regulate the resonant frequency of an RF electron gun. As part of this effort, we present initial test results for a benchmark temperature controller that combines a machine learning-based model and a predictive control algorithm. This is part of an on-going effort to develop adaptive, machine learning-based tools specifically to address control challenges found in particle accelerator systems.

  8. Initial experimental results of a machine learning-based temperature control system for an RF gun

    OpenAIRE

    Edelen, A. L.; Biedron, S. G.; Milton, S.V.; Chase, B. E.; Crawford, D J; Eddy, N.; Edstrom Jr., D.; Harms, E. R.; Ruan, J.; Santucci, J. K.; Stabile, P.

    2015-01-01

    Colorado State University (CSU) and Fermi National Accelerator Laboratory (Fermilab) have been developing a control system to regulate the resonant frequency of an RF electron gun. As part of this effort, we present initial test results for a benchmark temperature controller that combines a machine learning-based model and a predictive control algorithm. This is part of an on-going effort to develop adaptive, machine learning-based tools specifically to address control challenges found in par...

  9. Generation of femtosecond electron single pulse using laser photocathode RF gun

    International Nuclear Information System (INIS)

    A new laser photocathode RF electron gun was installed in the second linac of the S-band twin linac system of Nuclear Engineering Research Laboratory(NERL) of University of Tokyo in August in 1997. Since then, the behavior of the new gun has been tested and the characteristic parameters have been evaluated. At the exit of the gun, the energy is 4.7 MeV, the charge per bunch 1 nC, the pulse width is 10 ps(FWHM), respectively, for 6 MW RF power supply from a klystron. The electron bunch is accelerated up to 17 MeV. The horizontal normalized emittance is 1 π mm.mrad. Then, the bunch is compressed to be 440 fs(FWHM) with 0.35 nC by the chicane-type magnetic pulse compressor. The gun is planned to be used for femtosecond X-ray generation via the head-on Thomson scattering and laser wakefield acceleration in 1998. (author)

  10. Femtosecond electron beam generation by S-band laser photocathode RF gun and linac

    International Nuclear Information System (INIS)

    A laser photocathode RF electron gun was installed in the second linac of the S-hand twin linac system of Nuclear Engineering Research Laboratory (NERL) of University of Tokyo in August in 1997. Since then, the behavior of the new gun has been tested and the characteristic parameters have been evaluated. At the exit of the gun, the energy is 3.5 MeV, the charge per bunch 1∼2 nC, the pulse width is 10 ps(FWHM), respectively, for 6 MW RF power supply from a klystron. The electron bunch is accelerated up to 17 MeV and horizontal and vertical normalized emittances of 3 π mm.mrad are achieved. Then, the bunch is compressed to be 440 fs(FWHM) with 0.35 nC by the chicane-type magnetic pulse compressor. The linac with the gun and a new femto- and picosecond laser system is planned to be installed for femtosecond pulseradiolysis for radiation chemistry in 1999

  11. Evaluation of the back-bombardment effect in the ITC-RF gun for T-ACTS project at Tohoku University

    International Nuclear Information System (INIS)

    An ITC (independently tunable cells) RF gun is currently used to produce sub-picosecond electron pulses as part of the injector for coherent terahertz radiation at Tohoku University. Experiments and simulations of particle tracing by GPT show that the back-bombardment effect on the LaB6 cathode's surface is serious and should be controlled carefully. To evaluate the temperature increase due to back-bombardment a 2D model is created for heat transfer inside the cathode. In the 2D model, the back-streaming electrons are treated as external heat source as well as the cathode heater that heats the cathode from its side along with thermal radiation from its surface. The energy deposit of back-bombardment inside the cathode is calculated by EGS5 or Geant4 by use of the information of back-streaming electrons derived from GPT simulation. In addition, we will also compare the simulating results with experimental data on the increase of emission current density of cathode due to back-bombardment. (author)

  12. 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

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

    International Nuclear Information System (INIS)

    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

  14. Emissivity of a multibeam electron gun with a glassy carbon field-emission cathode

    Science.gov (United States)

    Bushuev, N. A.; Glukhova, O. E.; Grigor'ev, Yu. A.; Ivanov, D. V.; Kolesnikova, A. S.; Nikolaev, A. A.; Shalaev, P. D.; Shesterkin, V. I.

    2016-02-01

    A multibeam triode electron gun with a glassy carbon field-emission cathode that is intended for an O-type microwave amplifier is studied. The electric field strength and the current density at the microtips versus the distance to the center of a cell of the cathode-grid unit are calculated. Calculation data are compared with experimental results. It is shown that about 70% of the cathode current in each cell is accounted for by microtips arranged in a circumferential ring no wider than 20 μm. The field-emission current density inside the ring exceeds 40 A/cm2, and the current per microtip equals 43.1 μA.

  15. Development of Multiple Beam Guns for High Power RF Sources for Accelerators and Colliders

    International Nuclear Information System (INIS)

    There is a need for high power RF sources for the next generation of accelerators and colliders. Sources that operate at reduced beam voltage allow solid state power supplies with significant cost reduction over conventional pulse modulators. Multiple beam RF sources provide reduced beam voltage by using a multiplicity of beamlets that traverse the RF circuit through individual beam tunnels, reducing the space charge forces that drive the voltage requirement. The current generation of multiple beam devices typically use Brillouin focusing, which limits high power operation. The devices reported here utilize confined flow focusing which allows much tighter control of the electron beamlets and consequently, higher power operation. Progress in the development of a 100 MW multiple beam electron gun with confined flow focusing is reported

  16. High power test results of the first SRRC/ANL high current L-band RF gun.

    Energy Technology Data Exchange (ETDEWEB)

    Ho, C. H.

    1998-09-11

    A joint program is underway between the SRRC (Synchrotrons Radiation Research Center, Taiwan) and ANL (Argonne National Laboratory, USA) for developing a high current L-band photocathode rf guns. We have constructed an L-Band (1.3 Ghz), single cell rf photocathode gun and conducted low power tests at SRRC. High power rf conditioning of the cavity has been completed at ANL. In this paper we report on the construction and high power test results. So far we have been able to achieve > 120 MV/m axial electric field with minimal dark current. This gun will be used to replace the AWA (Argonne Wakefield Accelerator)[l] high current gun.

  17. 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.

  18. A mulitple cathode gun design for the eRHIC polarized electron source

    Energy Technology Data Exchange (ETDEWEB)

    Chang, X.; Ben-Zvi, I.; Kewisch, J.; Litvinenko, V.; Pikin, A.; Ptitsyn, V.; Rao, T.; Sheehy, B.; Skaritka, J.; Wang, E.; Wu, Q.; Xin, T.

    2011-03-28

    The future electron-ion collider eRHIC requires a high average current ({approx}50 mA), short bunch ({approx}3 mm), low emittance ({approx}20 {micro}m) polarized electron source. The maximum average current of a polarized electron source so far is more than 1 mA, but much less than 50 mA, from a GaAs:Cs cathode. One possible approach to overcome the average current limit and to achieve the required 50 mA beam for eRHIC, is to combine beamlets from multiple cathodes to one beam. In this paper, we present the feasibility studies of this technique. The future eRHIC project, next upgrade of RHIC, will be the first electron-heavy ion collider in the world. It requires polarized electron source with a high average current ({approx}50 mA), short bunch ({approx}3 mm), emittance of about 20 {micro}m and energy spread of {approx}1% at 10 MeV. The state-of-art polarized electron cathode can generate average current of about more than 1 mA, but much less than 50 mA. The current is limited by the low quantum efficiency, space charge and ultra-high vacuum requirement of the polarized cathode. A possible approach to achieve the 50 mA beam is to employ multiple cathodes, such as 20 cathodes, and funnel the multiple bunched beams from cathodes to the same axis. Fig.1 illustrates schematically the concept of combining the multiple beams. We name it as 'Gatling gun' because it bears functional similarity to a Gatling gun. Laser beams strike the cathodes sequentially with revolution frequency of 700 kHz. Each beam bunch is focused by a solenoid and is bent toward the combiner. The combiner with rotating bending field bends all bunches arriving the combiner with a rotational pattern to the same axis. The energy of each bunch is modified by a bunching cavity (112MHz) and a 3rd harmonic cavity (336MHz). The bunch length is compressed ballistically in the drift space and is frozen after energy has been boosted to 10 MeV by the Booster linac. Each beam bunch contains 3.5 n

  19. High Current Density, Long Life Cathodes for High Power RF Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ives, Robert Lawrence [Calabazas Creek Research,, Inc.; Collins, George [Calabazas Creek Research, Inc.; Falce, Lou [Consultant; Schwartzkopf, Steve [Ron Witherspoon, Inc.; Busbaher, Daniel [Semicon Associates

    2014-01-22

    This program was tasked with improving the quality and expanding applications for Controlled Porosity Reservoir (CPR) cathodes. Calabazas Creek Research, Inc. (CCR) initially developed CPR cathodes on a DOE-funded SBIR program to improve cathodes for magnetron injection guns. Subsequent funding was received from the Defense Advanced Research Projects Agency. The program developed design requirements for implementation of the technology into high current density cathodes for high frequency applications. During Phase I of this program, CCR was awarded the prestigious 2011 R&D100 award for this technology. Subsequently, the technology was presented at numerous technical conferences. A patent was issued for the technology in 2009. These cathodes are now marketed by Semicon Associates, Inc. in Lexington, KY. They are the world’s largest producer of cathodes for vacuum electron devices. During this program, CCR teamed with Semicon Associates, Inc. and Ron Witherspoon, Inc. to improve the fabrication processes and expand applications for the cathodes. Specific fabrications issues included the quality of the wire winding that provides the basic structure and the sintering to bond the wires into a robust, cohesive structure. The program also developed improved techniques for integrating the resulting material into cathodes for electron guns.

  20. 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.

  1. 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 (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.

  2. Performance evaluation of self-breakdown-based single-gap plasma cathode electron gun

    Indian Academy of Sciences (India)

    Niraj Kumar; Nalini Pareek; Udit Narayan Pal; Deepak Kumar Verma; Jitendra Prajapati; Mahesh Kumar; Bharat Lal Meena; Ram Prakash

    2014-06-01

    This paper presents the experimental studies on self-breakdown-based single-gap plasma cathode electron (PCE) gun (5–20 kV/50–160 A) in argon, gas atmosphere and its performance evaluation based on particle-in-cell (PIC) simulation code `OOPIC-Pro’.The PCE-Gun works in conducting phase (low energy, high current) of pseudospark discharge. It produces an intense electron beam, which can propagate more than 200 mm in the drift space region without external magnetic field. The profile of this beam in the drift space region at different breakdown conditions (i.e., gas pressures and applied voltages) has been studied and the experimental results are compared with simulated values. It is demonstrated that ∼30% beam current is lost during the propagation possibly due to space charge neutralization and collisions with neutral particles and walls.

  3. Measurement of groove features and dimensions of the vertical test cathode and the choke joint of the superconducting electron gun cavity of the Energy Recovery LINAC

    Energy Technology Data Exchange (ETDEWEB)

    Hammons, L.; Ke, M.

    2011-10-13

    A testing program for the superconducting electron gun cavity that has been designed for the Energy Recovery LINAC is being planned. The goal of the testing program is to characterize the RF properties of the gun cavity at superconducting temperatures and, in particular, to study multipacting that is suspected to be occurring in the choke joint of the cavity where the vertical test cathode is inserted. The testing program will seek to understand the nature and cause of this multipacting and attempt to eliminate it, if possible, by supplying sufficient voltage to the cavity. These efforts are motivated by the multipacting issues that have been observed in the processing of the fine-grain niobium gun cavity. This cavity, which is being processed at Thomas Jefferson National Laboratory for Brookhaven, has encountered multipacting at a gradient of approximately 3 MV/m and, to date, has resisted efforts at elimination. Because of this problem, a testing program is being established here in C-AD that will use the large-grain niobium gun cavity that currently resides at Brookhaven and has been used for room-temperature measurements. The large-grain and fine-cavities are identical in every aspect of construction and only differ in niobium grain size. Thus, it is believed that testing and conditioning of the large-grain cavity should yield important insights about the fine-grain cavity. One element of this testing program involves characterizing the physical features of the choke joint of the cavity where the multipacting is believed to be occurring and, in particular the grooves of the joint. The configuration of the cavity and the vertical test cathode is shown in Figure 1. In addition, it is important to characterize the groove of the vertical test cathode. The grooved nature of these two components was specifically designed to prevent multipacting. However, it is suspected that, because of the chemical processing that the fine-grain gun cavity underwent along with the

  4. RF pulse shape control using a recurrent algorithm for a FEL RF-gun cavity

    International Nuclear Information System (INIS)

    FEL application requires a very constant RF accelerating field during the pulse. A classical feedback regulation loop cannot be very efficient when pulse duration is just a few times longer than the filling time of the cavity as the loop gain cannot be high enough. For that reason, the authors decided to control the RF shape along the macropulse in a recurrent way: the pulse profile is corrected step by step by computation from the measurement of previous pulses and the desired shape. The control algorithm is given and its performances are presented

  5. Shaping the spatial periodic electron beams in the system of magnetron guns with secondary emission cathodes

    CERN Document Server

    Ajzatskij, N I; Zakutin, V V; Reshetnyak, N G; Romasko, V P; Volkolupov, Yu Ya; Krasnogolovets, M A

    2001-01-01

    The study on the electron beam generation processes in the system of the magnetron guns with the secondary-emission cathodes and anodes in form of periodically positioned metallic pins is carried out. It is shown, that the beam summary current of approximately 22 A is obtained in the system, consisting of four cells, which corresponds to the quadruplicate beam current value of the one cell. The pulse capacity thereby constituted approximately 600 kW. Such beams may be applied in the multipulse microwave devices

  6. Experimental investigation of a 1 kA/cm2 sheet beam plasma cathode electron gun

    International Nuclear Information System (INIS)

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm2 from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field

  7. Experimental investigation of a 1 kA/cm2 sheet beam plasma cathode electron gun

    Science.gov (United States)

    Kumar, Niraj; Narayan Pal, Udit; Kumar Pal, Dharmendra; Prajesh, Rahul; Prakash, Ram

    2015-01-01

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ˜1 kA/cm2 from pseudospark based argon plasma for pulse length of ˜200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field.

  8. Experimental investigation of a 1 kA/cm² sheet beam plasma cathode electron gun.

    Science.gov (United States)

    Kumar, Niraj; Pal, Udit Narayan; Pal, Dharmendra Kumar; Prajesh, Rahul; Prakash, Ram

    2015-01-01

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm(2) from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field. PMID:25638082

  9. Modular Low-Heater-Power Cathode/Electron Gun Assembly for Microwave and Millimeter Wave Traveling Wave Tubes

    Science.gov (United States)

    Wintucky, Edwin G.

    2000-01-01

    A low-cost, low-mass, electrically efficient, modular cathode/electron gun assembly has been developed by FDE Inc. of Beaverton, Oregon, under a Small Business Innovation Research (SBIR) contract with the NASA Glenn Research Center at Lewis Field. This new assembly offers significant improvements in the design and manufacture of microwave and millimeter wave traveling-wave tubes (TWT's) used for radar and communications. It incorporates a novel, low-heater-power, reduced size and mass, high-performance barium dispenser type thermionic cathode and provides for easy integration of the cathode into a large variety of conventional TWT circuits. Among the applications are TWT's for Earth-orbiting communication satellites and for deep space communications, where future missions will require smaller spacecraft, higher data transfer rates (higher frequencies and radiofrequency output power), and greater electrical efficiency. A particularly important TWT application is in the microwave power module (a hybrid microwave/millimeter wave amplifier consisting of a low-noise solid-state driver, a small TWT, and an electronic power conditioner integrated into a single compact package), where electrical efficiency and thermal loading are critical factors and lower cost is needed for successful commercialization. The design and fabrication are based on practices used in producing cathode ray tubes (CRT's), which is one of the most competitive and efficient manufacturing operations in the world today. The approach used in the design and manufacture of thermionic cathodes and electron guns for CRT's has been optimized for fully automated production, standardization of parts, and minimization of costs. It is applicable to the production of similar components for microwave tubes, with the additional benefits of low mass and significantly lower cathode heater power (less than half that of dispenser cathodes presently used in TWT s). Modular cathode/electron gun assembly. The modular

  10. Generation of femtosecond electron bunches using a laser photocathode RF gun linac

    International Nuclear Information System (INIS)

    Electron beams with pulse durations of picoseconds and femtoseconds have been applied to the accelerator physics application such as free electron lasers and laser-Comptom x-rays. The ultrashort electron bunches are also key element in time-resolved measurements including pulse radiolysis to improve the time resolution of the measurements. In this study, femtosecond electron bunches were generated using a laser photocathode RF gun linac and a magnetic bunch compressor at ISIR, Osaka University. The bunch lengths were evaluated by detecting coherent transition radiation (CTR) emitted from the electron bunches using a Michelson interferometer. (author)

  11. Half-Cell RF Gun Simulations with the Electromagnetic Particle-in-Cell Code VORPAL

    Science.gov (United States)

    Paul, K.; Dimitrov, D. A.; Busby, R.; Bruhwiler, D. L.; Smithe, D.; Cary, J. R.; Kewisch, J.; Kayran, D.; Calaga, R.; Ben-Zvi, I.

    2009-01-01

    We have simulated Brookhaven National Laboratory's half-cell superconducting RF gun design for a proposed high-current ERL using the three-dimensional, electromagnetic particle-in-cell code VORPAL. VORPAL computes the fully self-consistent electromagnetic fields produced by the electron bunches, meaning that it accurately models space-charge effects as well as bunch-to-bunch beam loading effects and the effects of higher-order cavity modes, though these are beyond the scope of this paper. We compare results from VORPAL to the well-established space-charge code PARMELA, using RF fields produced by SUPERFISH, as a benchmarking exercise in which the two codes should agree well.

  12. A high-charge and short-pulse RF photocathode gun for wake-field acceleration

    Science.gov (United States)

    Gai, W.; Li, X.; Conde, M.; Power, J.; Schoessow, P.

    1998-02-01

    In this paper we present a design report on 1-1/2 cell, L-Band RF photocathode gun which is capable of generating and accelerating electron beams with peak currents >10 kA. We address several critical issues of high-current RF photoinjectors such as longitudinal space charge effect, and transverse emittance growth. 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 100 nC beam at 18 MeV with r.m.s. bunch length 1.25 mm and normalized transverse emittance 108 mm mrad. Applications of this source beam for wake-field acceleration are also discussed.

  13. Design of an electron gun for terahertz radiation source

    International Nuclear Information System (INIS)

    An EC-ITC (External-Cathode Independently Tunable Cells) RF gun was employed with the aim of obtaining short-pulse bunches with high peak current for a terahertz radiation source. A gridded DC gun plays a key role as the external injecting electron source of the ITC RF gun, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the gridded DC gun should be 15 keV at most. A proper structure of the gridded gun with double-anode is shown to overcome the strong space-charge force on the cathode, which is able to generate 6 μs beam with 4.5 A current successfully. (authors)

  14. Design of an electron gun for terahertz radiation source

    CERN Document Server

    Li, Ji; Hu, Tongning; Chen, Qushan; Feng, Guangyao; Shang, Lei; Li, Chenglong

    2013-01-01

    With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an EC-ITC (External-Cathode Independently Tunable Cells) RF gun was employed. As the external injecting electron source of the ITC RF gun, a gridded DC gun plays a key role, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the gridded DC gun should be 15 KeV at most. A proper structure of the gridded gun is shown to overcome the strong space- charge force on the cathode, which is able to generate 6 {\\mu}s beam with 4.5A current successfully.

  15. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, O. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Degen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Lambiase, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meng, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rao, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Sheehy, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pietz, J. [Transfer Engineering and Manufacturing, Inc., Fremont, CA (United States); Ackeret, M. [Transfer Engineering and Manufacturing, Inc., Fremont, CA (United States); Yeckel, C. [Stangenes Industries, Palo Alto, CA (United States); Miller, R. [Stangenes Industries, Palo Alto, CA (United States); Dobrin, E. [Stangenes Industries, Palo Alto, CA (United States); Thompson, K. [Stangenes Industries, Palo Alto, CA (United States)

    2015-05-03

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  16. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    International Nuclear Information System (INIS)

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  17. High Precision Temperature Control of Normal-Conducting RF GUN for a High Duty Cycle Free-Electron Laser

    OpenAIRE

    Kruppa, K.; Pfeiffer, Sven; Lichtenberg, G.; Brinker, Frank; Decking, Winfried; Floettmann, Klaus; Krebs, Olaf; Schlarb, Holger; Schreiber, Siegfried

    2015-01-01

    High precision temperature control of the RF GUN is necessary to optimally accelerate thousands of electrons within the injection part of the European X-ray free-electron laser XFEL and the Free Electron Laser FLASH. A difference of the RF GUN temperature from the reference value of only 0.01 K leads to detuning of the cavity and thus limits the performance of the whole facility. Especially in steady-state operation there are some undesired temperature oscillations when using classical standa...

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

    International Nuclear Information System (INIS)

    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

  19. 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.

  20. LCLS Gun Solenoid Design Considerations

    International Nuclear Information System (INIS)

    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.

  1. 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.

  2. Multikiloampere magnetron gun with secondary emission at relativistic voltage

    International Nuclear Information System (INIS)

    Magnetron gun for voltage up 1000 kV and current more 1 kA was tested in pulse mode. The secondary emission nature of the cathode current was established. The identification was held basing on considered features of the exciting and on the maintenance of the secondary emission current. The gun may be used for charge particle accelerators and RF power sources

  3. Voltage pulse formation for energizing the magnetron gun with a secondary-emission cathode

    International Nuclear Information System (INIS)

    Various techniques have been investigated for forming a high-voltage pulse to energize magnetron guns with secondary-emission cathodes. To generate a powerful beam, it was necessary that the storage element in the modulator should have a low wave impedance. A capacitor and a low-impedance forming line were used as a storage element. The flat part of the pulse was formed by means of different correction circuits. The influence of correction circuit elements on the pulse form has been investigated. Consideration has been given to the circuits of spike control by means of the driving generator, and also, by including the correction circuits in the discharge circuit. Spike formation through the use of pulse-transformer parasitic parameters was also considered. The undertaken studies have demonstrated the possibility of creating a modulator for energizing the accelerator with electron energy up to 150 keV.

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

    International Nuclear Information System (INIS)

    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)

  5. Improvement of the laser system for RF-gun at SuperKEKB injector

    International Nuclear Information System (INIS)

    For SuperKEKB project, the electron beams with a charge of 5 nC and a normalized emittance of 10 μm are expected to be generated in photocathode RF gun at injector linac. Compared to the previous laser system, current ytterbium laser system is operating in high repetition rate of 25 Hz but suffering thermal effect. In order to minimize the thermal effect, ytterbium cascade laser design is proposed. The proposal is different from the standard ytterbium laser, 1035 nm laser is selected as pump source. As to the output or amplified laser at 1050 nm, the quantum defect can be reduced to just 1.5% with minimized thermal effect. Meanwhile, higher gain and less reabsorption can be obtained. At present, Yb:KGW and Yb:BOYS crystal are chosen as the gain materials. For out next step experiment, the laser properties of the crystals at 1050 nm are tested and studied. (author)

  6. Microwave measurements of the BNL/SLAC/UCLA 1.6 cell photocathode rf gun

    International Nuclear Information System (INIS)

    The longitudinal accelerating field E. has been measured as a function of azimuthal angle in the full cell of the cold test model for the 1.6 cell BNL/SLAC/UCLA number-sign 3 S-band RF Gun using a needle rotation/frequency perturbation technique. These measurements were conducted before and after symmetrizing the full cell with a vacuum pump out port and an adjustable short. Two different waveguide to full cell coupling schemes were studied. The dipole mode of the full cell is an order of magnitude less severe before symmetrization for the 0θ-coupling scheme. The multi-pole contribution to the longitudinal field asymmetry are calculated using standard Fourier series techniques. The Panofsky-Wenzel theorem is used in estimating the transverse emittance due to the multipole components of Ex

  7. Initial simulation studies of electron bunch from RF photocathode gun of DLS project

    International Nuclear Information System (INIS)

    A Free Electron Laser based compact light source, named as Delhi Light Source (DLS), is under construction at IUAC. The facility aims to produce THz and Infrared radiation by injecting high quality electron beam into an undulator magnet. In addition, intense X-rays can be obtained by bombarding the electron beam with a laser beam by the method of Inverse Compton scattering. The complete project is divided in to three phases. The first phase of the project aims at generating pre-bunched electron beam from a 2.6 cell room temperature RF photocathode gun operating at 2.86 GHz. The bunch train with a repetition rate of 10 Hz, will consist of 2, 4, 8 or 16 micro-bunches . By varying the separation between the microbunches, the tuning of the THz radiation produced from the undulator magnet can be performed. Metal photocathode will be used initially to generate the electron micro-bunches to keep the temporal spread small. This paper describes the simulation studies using ASTRA code for optimization of various parameters from RF photocathode gun upto the undulator entrance. The multiple parameters are optimized one at a time, for a single electron bunch, ensuring the desired output parameter is contained within tolerable limits. Beam optics simulation with multi electron bunches are also studied with variable number of 2, 4 and 8 micro-bunches with different micro-bunch spacing. In the simulation studies, attention is paid to optimize the fundamental beam parameters like the transverse emittance, energy spread, transverse/longitudinal beam size etc. The paper describes the simulation results with single and multi-electron bunches. (author)

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  10. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    International Nuclear Information System (INIS)

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods

  11. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    Science.gov (United States)

    Kondoh, Takafumi; Kashima, Hiroaki; Yang, Jinfeng; Yoshida, Yoichi; Tagawa, Seiichi

    2008-10-01

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods.

  12. Indigenous development of 50 kV, 1A high PRR solid state modulators for triode electron gun for RF linac

    International Nuclear Information System (INIS)

    A challenging design and development effort for the triode type electron gun and its associated component and test systems was taken up at Pulse High Power Microwave Division, PHPMD, RRCAT. The electron gun needs upto 50kV pulse voltage with over 12 microsecs pulse duration and PRR upto 200 Hz. The emission from the electron gun cathode was designed to be 1 Amp. Keeping in view these requirements of the triode type electron gun an all solid state modulator was designed, developed and used for the electron guns. The solid state modulator has been subjected to stringent qualification tests along with long duration endurance testing. The present paper discusses the design, development and commissioning aspects of the solid state electron gun modulator and its results with the electron gun used in the linac. (author)

  13. FEM analysis of X-band RF gun using 6-node isoparametric element

    International Nuclear Information System (INIS)

    Electron linear accelerators are applied to use of medical and industrial fields, which are studied on down sizing by making higher frequency and currently have an X-band (11.424 GHz) range and above. In order to down sizing accelerators for cost reduction and convenience, it requires high-precise and effective accelerating cavity designing. In this paper, we will report on an evaluation of an electromagnetic field simulator we are developing. Our simulator is high precise and specialized in accelerator cavity designing. We chose a spherical cavity as a test model for the evaluation, and we analyzed this model by using the simulator. Then we got the electromagnetic distribution as a TM01 mode on the cavity. By comparing this numerical solution and theoretical solution as an eigenvalue, we found a precision minimized to about 10-6 as a relative error. By subdividing elements, the precision was improved on 10-8 order, but from this, the precision got worse by increasing number of partitions. Therefore we are going to try to find the cause of it. Additionally, we compared our simulator and Superfish code using X-band RF gun cavity. (author)

  14. Multi-objective Optimizations of a Normal Conducting RF Gun Based Ultra Fast Electron Diffraction Beamline

    CERN Document Server

    Gulliford, C; Maxson, J; Bazarov, I

    2016-01-01

    We present the results of multi-objective genetic algorithm optimizations of a potential single shot ultra fast electron diffraction beamline utilizing a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed for a charge of 1e6 electrons. Analysis of the solutions is discussed, as are the effects of disorder induced heating. In particular, for a charge of $10^6$ electrons and final beam size greater than or equal to 25 microns, we found a relative coherence length of 0.07, 0.1, and 0.2 nm/micron for a final bunch length of approximately 5, 30, and 100 fs, respectively. These results demonstrate the viability of using geneti...

  15. Photothermal cathode measurements at the Advanced Photon Source

    International Nuclear Information System (INIS)

    The Advanced Photon Source (APS) ballistic bunch compression (BBC) gun in the Injector Test Stand (ITS) presently uses an M-type thermionic dispenser cathode as a photocathode. This photothermal cathode offers substantial advantages over conventional metal photocathodes, including easy replacement and easy cleaning via the cathode's built-in heater. We present the results of photoemission measurements as a function of cathode heater power, laser pulse energy, and applied rf field strength.

  16. Grid pulser for an electron gun with a thermionic cathode for the high-power operation of a terahertz free-electron laser

    International Nuclear Information System (INIS)

    A grid pulser for a thermionic-cathode electron gun for an L-band electron linac with an RF frequency of 1.3 GHz was developed in an effort to increase the power of a terahertz (THz) free-electron laser (FEL) based on the linac. The grid pulser can generate a train of electron pulses with a 5-ns duration at intervals of 36.9 ns or at a repetition frequency of 27 MHz, which is the 48th sub-harmonic of the RF frequency, and with a peak current of up to 2.4 A or higher, which is four times higher than the current that can be obtained with the conventional grid pulser. In combination with the sub-harmonic buncher (SHB) system, whose fundamental frequency is 108 MHz (the 12th sub-harmonic of the RF frequency), an electron beam that comprises electron bunches separated by 36.9-ns intervals for a period of 8 μs can be successfully accelerated using the linac to an energy of 15 MeV under the condition that the average beam current or, correspondingly, the beam loading in the acceleration tube of the linac is the same as that obtained using the conventional grid pulser. The time-resolved energy spectrum indicates that the energy is constant over the latter 6 μs and that the energy spread is 1.2% (FWHM); this performance satisfies the requirements for the FEL. The bunch charge measured at the end of the FEL beamline is 4 nC, which is four times higher than that obtained using the conventional grid pulser

  17. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes

    Science.gov (United States)

    Kumar, Niraj; Pal, Dharmendra Kumar; Jadon, Arvind Singh; Pal, Udit Narayan; Rahaman, Hasibur; Prakash, Ram

    2016-03-01

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ˜50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  18. Secondary emission electron gun using external primaries

    Science.gov (United States)

    Srinivasan-Rao, Triveni; Ben-Zvi, Ilan; Kewisch, Jorg; Chang, Xiangyun

    2007-06-05

    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.

  19. Optical modulation of electron beam using the opto-semiconductor device on the photocathode RF gun for the radiation therapy

    International Nuclear Information System (INIS)

    The radiation therapy of cancer is developing to un-uniform irradiation, for concentrating dose to a tumor and reducing dose to normal tissue. For the un-uniform irradiation, optical modulation of electron beam using the Digital Micro Mirror Device was studied on a photocathode RF gun. The optical modulation of electron beam and dynamic control succeeded by a digital micro mirror device. Fundamental data such as the spatial resolution and the contrast of the optical modulated electron beam was measured. It will be reported that the relations between the intensity distribution and the emittance. (author)

  20. 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.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-23

    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.

  3. Beam dynamics enhancement due to accelerating field symmetrization in the BNL/SLAC/UCLA 1.6 cell S-band photocathode RF gun

    International Nuclear Information System (INIS)

    A 1.6 cell photocathode S-Band gun developed by the BNL/SLAC/UCLA collaboration is now in operation at the Brookhaven Accelerator Test Facility (ATF). One of the main features of this RF gun is the symmetrization of the RF coupling iris with an identical vacuum pumping port located in the full cell. The effects of the asymmetry caused by the RF coupling iris were experimentally investigated by positioning a metallic plunger at the back wall of the vacuum port iris. The higher order modes produced were studied using electron beamlets with 8-fold symmetry. The 8-fold beamlets were produced by masking the laser beam. These experimental results indicate that the integrated electrical center and the geometrical center of the gun are within 175 microm. Which is within the laser alignment tolerance of 250 microm

  4. Ultra-fast pulse radiolysis system combined with a laser photocathode RF gun and a femtosecond laser

    CERN Document Server

    Muroya, Y; Watanabe, T; Wu, G; Kobayashi, T; Yoshii, K; Ueda, T; Uesaka, M; Katsumura, Y

    2002-01-01

    In order to study the early events in radiation physics and chemistry, two kinds of new pulse radiolysis systems with higher time resolution based on pump-and-probe method have been developed at the Nuclear Engineering Research Laboratory, the University of Tokyo. The first one, a few picosecond (2 ps at FWHM) electron beam (pump) from an 18 MeV S-band Linac using a laser photocathode RF gun (BNL/KEK/SHI type: GUN IV) was operated with a femtosecond laser pulse (100 fs at FWHM), which also acted as the analyzing light (probe). The synchronization precision between the pump and the probe was 1.7 ps (rms). In a 1.0 cm sample cell, a time resolution of 12 ps was achieved. The second one, a picosecond (4 ps at FWHM) electron pulse from a 35 MeV S-band Linac employing a conventional thermionic gun with a sub-harmonic buncher, was synchronized with the femtosecond laser pulse, with a synchronization jitter of 2.8 ps (rms). A time resolution of 22 ps was obtained with 2 cm cell. This makes it possible to do the puls...

  5. Polarized Electron Gun Development at the Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    Development of two different polarized electron guns is ongoing at BNL. One aims at extremely high brightness at a moderate beam current. This design uses a superconducting RF gun and a test setup is built to show that a Gallium-Arsenide cathode with negative affinity has a sufficiently long quantum efficiency lifetime in such an environment. An electron injector using this technology may eliminate the need of the electron damping ring and a long transport line at the International Linear Collider. The other project aims at producing a high beam current with moderate emittance requirements, dubbed the 'Gatling gun'. In this DC gun, bunches are extracted from 20 separate cathodes and merged into a single beam using a rotating magnetic field. Such an electron gun could serve as an injector for the electron-ion collider eRHIC, which is planned at BNL. We will report on the status of these projects.

  6. Superconducting 112 MHz QWR electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Belomestnykh, S.; Ben-Zvi, I.; Boulware, C.H.; Chang, X.; Grimm, T.L.; Rao, T.; Siegel, B.; Skaritka, J.; Than, R.; Winowski, M.; Wu, Q.; Xin, T.; Xue, L.

    2011-07-25

    Brookhaven National Laboratory and Niowave, Inc. have designed and fabricated a superconducting 112 MHz quarter-wave resonator (QWR) electron gun. The first cold test of the QWR cryomodule has been completed at Niowave. The paper describes the cryomodule design, presents the cold test results, and outline plans to upgrade the cryomodule. Future experiments include studies of different photocathodes and use for the coherent electron cooling proof-of-principle experiment. Two cathode stalk options, one for multi-alkali photocathodes and the other one for a diamond-amplified photocathode, are discussed. A quarter-wave resonator concept of superconducting RF (SRF) electron gun was proposed at BNL for electron cooling hadron beams in RHIC. QWRs can be made sufficiently compact even at low RF frequencies (long wavelengths). The long wavelength allows to produce long electron bunches, thus minimizing space charge effects and enabling high bunch charge. Also, such guns should be suitable for experiments requiring high average current electron beams. A 112 MHz QWR gun was designed, fabricated, and cold-tested in collaboration between BNL and Niowave. This is the lowest frequency SRF gun ever tested successfully. In this paper we describe the gun design and fabrication, present the cold test results, and outline our plans. This gun will also serve as a prototype for a future SRF gun to be used for coherent electron cooling of hadrons in eRHIC.

  7. 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.

  8. Resonant cavity Vircator driven by a thermionic cathode electron beam gun

    Energy Technology Data Exchange (ETDEWEB)

    Kraft, R. [Texas Instrument, Dallas, TX (United States)

    1993-12-01

    A resonant cavity Vircator (virtual cathode oscillator) driven by an electron beam emitted from a broad area thermionic cathode has been tested at Textron Defense Systems. Narrow bandwidth (1.0 MHz at the {minus}3 dB level) excitation of the TM{sub 0.23} mode of a cylindrical resonant cavity was observed at a frequency of 986 MHz with a pulse length of 1.2 {mu}s. The single cavity mode excitation is attributed to the constant voltage and current electron beam emitted form the thermionic cathode.

  9. High-gradient High-charge CW Superconducting RF gun with CsK2Sb photocathode

    CERN Document Server

    Pinayev, Igor; Tuozzolo, Joseph; Brutus, Jean Clifford; Belomestnykh, Sergey; Boulware, Chase; Folz, Charles; Gassner, David; Grimm, Terry; Hao, Yue; Jamilkowski, James; Jing, Yichao; Kayran, Dmitry; Mahler, George; Mapes, Michael; Miller, Toby; Narayan, Geetha; Sheehy, Brian; Rao, Triveni; Skaritka, John; Smith, Kevin; Snydstrup, Louis; Than, Yatming; Wang, Erdong; Wang, Gang; Xiao, Binping; Xin, Tianmu; Zaltsman, Alexander; Altinbas, Z; Ben-Zvi, Ilan; Curcio, Anthony; Di Lieto, Anthony; Meng, Wuzheng; Minty, Michiko; Orfin, Paul; Reich, Jonathan; Roser, Thomas; Smart, Loralie A; Soria, Victor; Theisen, Charles; Xu, Wencan; Wu, Yuan H; Zhao, Zhi

    2015-01-01

    High-gradient CW photo-injectors operating at high accelerating gradients promise to revolutionize many sciences and applications. They can establish the basis for super-bright monochromatic X-ray free-electron lasers, super-bright hadron beams, nuclear- waste transmutation or a new generation of microchip production. In this letter we report on our operation of a superconducting RF electron gun with a record-high accelerating gradient at the CsK2Sb photocathode (i.e. ~ 20 MV/m) generating a record-high bunch charge (i.e., 3 nC). We briefly describe the system and then detail our experimental results. This achievement opens new era in generating high-power electron beams with a very high brightness.

  10. Development of ultra-violet femtosecond pulse radiolysis system based on a photocathode rf electron-gun linac

    International Nuclear Information System (INIS)

    Two important radical species of alkyl radical (R·) and hydroxyl radicals (OH·) in nuclear fuel reprocessing or radiation cancer therapy have absorption bands around the 250 nm in Ultra-violet region. Despite the OH· and R· are important active species in the radiation chemistry, since those absorption coefficients are small and lack of time resolution of pulse radiolysis, a direct study of the reaction dynamics has been difficult until now. In order to elucidate the formation and reaction with solutes, measurable wavelength was extended to ultraviolet of the femtosecond pulse radiolysis system using a photocathode RF gun accelerator. Problems of ultraviolet femtosecond pulse radiolysis measurement, the time dependent behaviors of R· and OH· are reported. (author)

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

    International Nuclear Information System (INIS)

    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

  12. Performance Study of K2CsSb Photocathode inside a DC High Voltage Gun

    International Nuclear Information System (INIS)

    In the past decade, there has been considerable interest in the generation of tens of mA average current in a photoinjector. Until recently, GaAs:Cs cathodes and K2CsSb cathodes have been tested successfully in DC and RF injectors respectively for this application. Our goal is to test the GaAs:Cs in RF injector and the K2CsSb cathode in the DC gun in order to widen our choices. Since the multialkali cathode is a compound with uniform stochiometry over its entire thickness, we anticipate that the life time issues seen in GaAs:Cs due surface damage by ion bombardment would be minimized with this material. Hence successful operation of the K2CsSb cathode in DC gun could lead to a relatively robust electron source capable of delivering ampere level currents. In order to test the performance of K2CsSb cathode in a DC gun, we have designed and built a load lock system that would allow the fabrication of the cathode at BNL and its testing at JLab. In this paper, we will present the design of the load-lock system, cathode fabrication, and the cathode performance in the preparation chamber and in the DC gun.

  13. Annular cathode electron gun for in-line injection in a race-track microtron

    International Nuclear Information System (INIS)

    An efficient and dependable injection system is an important factor in the overall performance capability of any accelerator. A compact annular geometry electron gun which allows direct, efficient injection of electrons into the microwave accelerating cavity of the 8 MeV race track microtron of the Physics Department of the Poona University, has been designed, built and tested. Electrons are emitted from a 0.1 mm diameter tungsten filament and formed into a hollow beam using a grid electrode and anode aperture. The particular geometries and operating voltages for various electrodes of the gun were evolved using the electrolytic tank method. The qun was tested upto accelerating voltages of 20 KV which corresponds to the optimum injection energy for acceptance in the 8 MeV race track microtron. Currents of 300 mA were obtained at the highest operatina voltages. The minimum diameter of the beam was 3 mm and was situated at the mid-point of the accelerating cavity. Attempts at further improving the gun performance are now in progress. (author)

  14. Photoelectron production in an x-band RF gun for free electron laser and nonlinear electron-photon scattering experiments

    International Nuclear Information System (INIS)

    A high brightness and short pulse electron source is under development for use in a Free Electron Laser and in electron-photon scattering experiments. Accelerated photoelectrons have been produced from a 1.5 cell 8.5 GHz RF gun using an amplified 100 fs ultra-violet laser pulse. Ongoing improvements in the laser and RF system should result in achieving desired system performance: 5 MeV electrons in 1.5 ps, 1 nC bunches with a normalized rms emittance of 2.5 mm-mrad. Electron bunches would be delivered in bursts of 100 pulses at 2.4 GHz every 10 Hz to drive a chirped pulse free electron laser. Such a microwave source, based on coherent emission of synchrotron radiation, could achieve power levels of 2.2 MW in a 15 ps FWHM pulse with a bandwidth extending from 125 to 225 GHz. The photoinjector will also provide an ideal source of relativistic electrons for investigating basic interactions: nonlinear Compton scattering, Kapitza-Dirac scattering and ponderomotive scattering (laser acceleration)

  15. The influence of zero-mode on beam properties at 1.6 cell photocathode RF gun

    International Nuclear Information System (INIS)

    Recently, due to multi-bunch laser injection, it is worried that 0 mode, which is not considerable with single-bunch injection, could be excited by beam loading and would degrade the beam properties. Then, we evaluated the influence in a BNL/SLAC/UCLA 1.6 cell photocathode RF gun, which is made use of widely, by using particle tracking simulations. We assumed the charge in a bunch was 1 nC, and the frequency of the laser injection was the same as that of RF electric field (2856 MHz). As a result, the electric field of the 0 mode became larger and its phase changed by nearly 180deg compared with the case without beam loading. Hence, the influence of the 0 mode on the beam properties, i.e. energy spread, transverse emittance, and bunch length, showed the opposite behavior to the single-bunch injection scheme. The change in energy spread by 0 mode at 10deg laser injection phase was about -20% without beam loading and +40% with beam loading. (author)

  16. 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...

  17. Theoretical and experimental studies of hyperfrequency electron guns with high brightness

    International Nuclear Information System (INIS)

    Starting from June 1986 a single cavity RF gun with thermionic cathode (LaB6) was studied and constructed at the Institute of High Energy Physics, Academia Sinica, Beijing, P.R. China. This RF gun was used as the injector of a 30 MeV Linac for the Beijing Free Electron Laser Project. In the experiments the electron back-bombardment effect and another phenomenon connected with cathode temperature were observed. After carefully choosing the operation parameters, this RF gun injector could stably provide electron beams suitable for doing preliminary FEL experiments. Based on the theoretical analysis a computer code (including space charge forces) was written to simulate the dynamics of electrons in this injector. Since May 1989, at LAL, Orsay France, the photocathode RF gun was investigated theoretically and new design criteria were established. Based on these criteria a two decoupled cavities RF gun, using a laser triggered photocathode, has been designed for the 'LAL/Orsay RF gun project' (CANDELA), and model cavities have been fabricated. Based on the model cavity measurement results, the final cavities have been fabricated and measured. Aiming at reducing further the emittance of electron bunches coming out of the second cavity, linear and nonlinear emittance compensating techniques have been proposed. As a new kind of electron injector suitable for FEL and future e+e- linear colliders, a travelling wave RF gun has been investigated theoretically and compared with the standing wave RF gun. Some preliminary numerical calculations have been made also. Stimulated by the experimental results on the model cavities, several useful analytical formulae have been derived and verified by the experimental results: (1) Analytical formulae for the coupling coefficient β of a cavity-waveguide coupling system. (2) Analytical formulae for the resonant frequency changes due to opening apertures on cavity walls. (3) Analytical formulae for the coupling coefficient k (or group

  18. Microhardness study of Ti(C, N films deposited on stainless steel 316 by the hallow cathode discharge gun

    Directory of Open Access Journals (Sweden)

    A.J. Novinrooz

    2005-12-01

    Full Text Available Purpose: The micro hardness properties of Titanium Carbonitride composite coated on SS-316 substrates were studied to achieve a desired harden surfaces.Design/methodology/approach: Hollow Cathode Discharge gun (HCD–gun was employed for deposition of the Ti(C, N on SS-316. The evaporated and ionized metal (Ti was coated as an under layer with 0.5 ampere beam current and 100 volt bias voltage. The reactant nitrogen and methane gasses were fed through inlet in to the chamber containing Ti element to form Ti (C, N matrix with an optimized ratio.Findings: In this work, Glow Discharge Optical emission Spectroscopy (GDOS used for compositional analysis of the content elements. On the bases of this operation it was revealed the existence of Ti, C, N elements, X-ray diffraction (XRD technique was utilized to investigate films crystalline structure. The investigation showed that samples with different stoichiometry have a fcc structure with (111 plan of reflection. The atomic ratio of carbon and nitrogen were measured using energy dispersive X-ray (EDX analysis. The optimized value was funned to be TiC0.87 N0.13. The atomic force microscopy (AFM and scanning electron microscopy (SEM were employed to study the films microstructure. A hardness of 3250 HV was obtained in the carbon content C/C+ N atomic ratio of 9 to 1 using a Vickers microhardness tester.Research limitations/implications: As the study was carried out on a limited surfaces, we shall endeavor further attempt on large area deposition.Practical implications: The tools coated in titanium accompanied by nitride and carbide has shown significant improvement. Good compatibility of Ti (C, N compound makes these composite suitable in various technical and industrial applications.Originality/value: It may be remarked that, the hardness obtained in this work is very encouraging and therefore, it is convenient to regard this as a privileged step taken in tool manufacturing aspect.

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

    Institute of Scientific and Technical Information of China (English)

    WANG Er-Dong; ZHAO Kui; J(o)rg 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.

  20. A Measurement Method of Time Jitter of a Laser Pulse with Respect to the Radio-Frequency Wave Phase in a Photocathode Radio-Frequency Gun

    Institute of Scientific and Technical Information of China (English)

    刘圣广; 李永贵; 王鸣凯

    2002-01-01

    In a photo-cathode radio-frequency (rf) gun, the micro-bunched charge output from the gun is dependent linearly on the laser injection phase, due to the Scottay effect in the process of photoemission and the procedure of the electron longitudinal acceleration. Based on this principle, a new method is proposed, which should be utilized to measure the time jitter between the driving laser pulse and the rf phase with a very high resolution of a few tens of femtoseconds.

  1. 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.

  2. R&D Requirements, RF Gun Mode Studies, FEL-2 Steady-State Studies, Preliminary FEL-1 Time-Dependent Studies, and Preliminary Layout Option Investigation

    OpenAIRE

    Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory; Ratti, Alex; Staples, John; Wilcox Russell; Wurtele, Jonathan; Zholents, Alexander

    2005-01-01

    This report constitutes the third deliverable of LBNL s contracted role in the FERMI @ Elettra Technical Optimization study. It describes proposed R&D activities for the baseline design of the Technical Optimization Study, initial studies of the RF gun mode-coupling and potential effects on beam dynamics, steady-state studies of FEL-2 performance to 10 nm, preliminary studies of time-dependentFEL-1 performance using electron bunch distribution from the start-to-end studies, and a prelimi...

  3. Impulse electron gun with plasma cathode for realization of large diameter tube-shaped beams

    International Nuclear Information System (INIS)

    There are presented the results of investigations of a plasma electron source based on the gas discharge in a coaxial system of electrodes with longitudinal magnetic field. The examination is fulfilled from the viewpoint of applying the source as a plasma cathode for hybrid plasma-waveguide slow-wave structures on the basis of a disk-loaded coaxial. The source is optimized in order to get a powerful (up to 100 kW) nonrelativistic electron beam with the annular cross-section of a large diameter in the regime of relatively long current pulses (up to 0.2 ms) under the gas pressure ∼ 5 centre dot 10-4 mm Hg in the area of the discharge burning

  4. Back bombardment for dispenser and lanthanum hexaboride cathodes

    Science.gov (United States)

    Bakr, Mahmoud; Kinjo, R.; Choi, Y. W.; Omer, M.; Yoshida, K.; Ueda, S.; Takasaki, M.; Ishida, K.; Kimura, N.; Sonobe, T.; Kii, T.; Masuda, K.; Ohgaki, H.; Zen, H.

    2011-06-01

    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 (LaB6) 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 6μs duration, the DC cathode experiences a large change in the temperature compared with LaB6, 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.

  5. 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

  6. Ion plasma electron gun

    International Nuclear Information System (INIS)

    In the disclosed electron gun positive ions generated by a hollow cathode plasma discharge in a first chamber are accelerated through control and shield grids into a second chamber containing a high voltage cold cathode. These positive ions bombard a surface of the cathode causing the cathode to emit secondary electrons which form an electron beam having a distribution adjacent to the cathode emissive surface substantially the same as the distribution of the ion beam impinging upon the cathode. After passing through the grids and the plasma discharge chamber, the electron beam exits from the electron gun via a foil window. Control of the generated electron beam is achieved by applying a relatively low control voltage between the control grid and the electron gun housing (which resides at ground potential) to control the density of the positive ions bombarding the cathode

  7. R and D Requirements, RF Gun Mode Studies, FEL-2 Steady-State Studies, Preliminary FEL-1 Time-Dependent Studies, and Preliminary Layout Option Investigation

    International Nuclear Information System (INIS)

    This report constitutes the third deliverable of LBNLs contracted role in the FERMI (at) Elettra Technical Optimization study. It describes proposed RandD activities for the baseline design of the Technical Optimization Study, initial studies of the RF gun mode-coupling and potential effects on beam dynamics, steady-state studies of FEL-2 performance to 10 nm, preliminary studies of time-dependent FEL-1 performance using electron bunch distribution from the start-to-end studies, and a preliminary investigation of a configuration with FEL sinclined at a small angle from the line of the linac

  8. HIGH AVERAGE CURRENT LOW EMITTANCE BEAM EMPLOYING CW NORMAL CONDUCTING GUN.

    Energy Technology Data Exchange (ETDEWEB)

    CHANG,X.; BEN-ZVI, I.; KEWISCH, J.; PAI, C.

    2007-06-25

    CW normal conducting guns usually do not achieve very high field gradient and waste much RF power at high field gradient compared to superconducting cavities. But they have less trapped modes and wakefields compared to the superconducting cavities due to their low Q. The external bucking coil can also be applied very close to the cathode to improve the beam quality. By using a low frequency gun with a recessed cathode and a carefully designed beam line we can get a high average current and a high quality beam with acceptable RF power loss on the cavity wall. This paper shows that the CW normal conducting gun can be a backup solution for those projects which need high peak and average current, low emittance electron beams such as the Relativistic Heavy Ion Collider (RHIC) e-cooling project and Energy Recovery Linac (Em) project.

  9. 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.

  10. Recent developments of low-emittance electron gun for accelerator

    International Nuclear Information System (INIS)

    Recent developments of low-emittance electron guns for accelerator are reviewed. In the accelerator field, DC biased triode thermionic gun (Pierce type gun) has been widely used and is still conventional. On the other hand, because of strong demands on the high brightness electron beam by FEL and other advanced accelerator concepts based on linear accelerator, the low emittance beam generation becomes one of the most important issue in the accelerator science. The R and D effort is 'accelerated' by two technological innovations, photo-cathode and RF gun. They made a large improvement on the beam emittance. After the explanations on the technical and physical aspects of the low emittance electron beam generation, advanced electron sources for accelerators are reviewed. (author)

  11. Operational Experience with the Nb/Pb SRF Photoelectron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Kamps, T; Barday, R; Jankowiak, A; Knoblock, J; Kugeler, O; Matveenko, A N; Neumann, A; Quast, T; Rudolph, J; Schubert, S G; Volker, J; Kneisel, P; Nietubyc, R; Sekutowicz, J K; Smedley, J; Teichert, J; Volkov, V

    2012-07-01

    SRF photoelectron guns offer the promise of high brightness, high average current beam production for the next generation of accelerator driven light sources such as free electron lasers, THz radiation sources or energy-recovery linac driven synchrotron radiation sources. In a first step a fully superconducting RF (SRF) photoelectron gun is under development by a collaboration between HZB, DESY, JLAB, BNL and NCBJ. The aim of the experiment is to understand and improve the performance of a Nb SRF gun cavity coated with a small metallic Pb cathode film on the cavity backplane. This paper describes the highlights from the commissioning and beam parameter measurements. The main focus is on lessons learned from operation of the SRF gun.

  12. 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)

  13. Microstructural and electrochemical properties of rf-sputtered LiMn2O4 thin film cathodes

    Science.gov (United States)

    Jayanth Babu, K.; Jeevan Kumar, P.; Hussain, O. M.

    2012-12-01

    Lithium transition metal oxides have received considerable attention in recent years as high voltage positive electrode materials in the fabrication of all solid state microbatteries. Among various lithium-based cathode materials, LiMn2O4 is one of the most promising cathode materials as it offers high energy density, high cell voltage, low cost, and low toxicity over the other electrode materials. Thin films of LiMn2O4 were prepared by radio frequency magnetron sputtering on gold-coated silicon substrates under various substrate temperatures ranging from 373 to 673 K in a partial pressure of 3 × 10-3 mbar with rf power 100 Watts. In the present investigation, the influence of substrate temperature on the growth and microstructural properties was studied. The films deposited at a substrate temperature less than 473 K was found to be X-ray amorphous. The initial crystallization has been observed at a substrate temperature of 523 K. The X-ray diffraction patterns of the films deposited in the substrate temperature range 523-673 K exhibited predominant (111) orientation representing cubic spinel structure with Fd3m symmetry. The grain size was found to be increased with the increase of substrate temperature as evidenced from SEM studies. However, additional impurity phases like Mn3O4 were observed for the films deposited at higher substrate temperatures (>673 K) because of re-evaporation of Li+ ions in the films. The electrochemical (EC) studies were carried for the films deposited at T s = 673 K in aqueous media in the potential window of 0.0-1.2 V exhibited better electrochemical performance suggesting that the films are well suited as binder free thin film cathode material for commercially viable Li-ion secondary batteries.

  14. Improving the performance of stainless-steel DC high voltage photoelectron gun cathode electrodes via gas conditioning with helium or krypton

    International Nuclear Information System (INIS)

    Gas conditioning was shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns, thus providing a reliable means to operate photoguns at higher voltages and field strengths. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. We have studied five stainless steel electrodes (304L and 316LN) that were polished to approximately 20 nm surface roughness using diamond grit, and evaluated inside a high voltage apparatus to determine the onset of field emission as a function of voltage and field strength. The field emission characteristics of each electrode varied significantly upon the initial application of voltage but improved to nearly the same level after gas conditioning using either helium or krypton, exhibiting less than 10 pA field emission at −225 kV bias voltage with a 50 mm cathode/anode gap, corresponding to a field strength of ∼13 MV/m. Field emission could be reduced with either gas, but there were conditions related to gas choice, voltage and field strength that were more favorable than others

  15. Numerical simulation of transport of a high-current electron beam generated by the secondary-emission cathode gun in a decreasing solenoidal field

    International Nuclear Information System (INIS)

    The software tool has been developed for computing the electron beam formation by means of the secondary-emission cathode magnetron gun in the electron energy range between 30 and 65 keV at beam transport in a decreasing magnetic field of the solenoid. Numerical simulation data on the tubular electron flow motion and visualization are presented. The beam current was investigated versus the amplitude and gradient of the field decrease, and also, versus the initial beam particle distribution in the phase space. It has been found that for the given simulation conditions, the magnetic field reconfiguration has an effect only on the total displacement of the electron beam, without causing a noticeable change in the shape of the final flow distribution along the longitudinal coordinate

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

    Science.gov (United States)

    Gai, W.; Li, X.; Conde, M.; Power, J.; Schoessow, P.

    1999-07-01

    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.

  17. A measurement method of time jitter of a laser pulse with respect to the radio-frequency wave phase in a photocathode radio-frequency gun

    International Nuclear Information System (INIS)

    In a photo-cathode radio-frequency (rf) gun, the micro-bunched charge output from the gun is dependent linearly on the laser injection phase, due to the Scottay effect in the process of photoemission and the procedure of the electron longitudinal acceleration. Based on this principle, a new method is proposed, which should be utilized to measure the time jitter between the driving laser pulse and the rf phase with a very high resolution of a few tens of femto-seconds

  18. Progress Toward a Gigawatt-Class Annular Beam Klystron with a Thermionic Electron Gun

    Science.gov (United States)

    Fazio, M.; Carlsten, B.; Farnham, J.; Habiger, K.; Haynes, W.; Myers, J.; Nelson, E.; Smith, J.; Arfin, B.; Haase, A.

    2002-08-01

    In an effort to reach the gigawatt power level in the microsecond pulse length regime Los Alamos, in collaboration with SLAC, is developing an annular beam klystron (ABK) with a thermionic electron gun. We hope to address the causes of pulse shortening in very high peak power tubes by building a "hard-vacuum" tube in the 10-10 Torr range with a thermionic electron gun producing a constant impedance electron-beam. The ABK has been designed to operate at 5 Hz pulse repetition frequency to allow for RF conditioning. The electron gun has a magnetron injection gun configuration and uses a dispenser cathode running at 1100 degC to produce a 4 kA electron beam at 800 kV. The cathode is designed to run in the temperature-limited mode to help maintain beam stability in the gun. The beam-stick consisting of the electron gun, an input cavity, an idler cavity, and drift tube, and the collector has been designed collaboratively, fabricated at SLAC, then shipped to Los Alamos for testing. On the test stand at Los Alamos a low voltage emission test was performed, but unfortunately as we prepared for high voltage testing a problem with the cathode heater was encountered that prevented the cathode from reaching a high enough temperature for electron emission. A post-mortem examination will be done shortly to determine the exact cause of the heater failure. The RF design has been proceeding and is almost complete. The output cavity presents a challenging design problem in trying to efficiently extract energy from the low impedance beam while maintaining a gap voltage low enough to avoid breakdown and a Q high enough to maintain mode purity. In the next iteration, the ABK will have a new cathode assembly installed along with the remainder of the RF circuit. This paper will discuss the electron gun and the design of the RF circuit along with a report on the status of the work.

  19. 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.

  20. Beam dynamics studies in a low-frequency high-peak power laser-driven RF gun

    International Nuclear Information System (INIS)

    An IR-FEL experiment (ELSA) is under construction at Bruyeres-le-Chatel. The injector consists of a laser-driven photocathode placed inside a 144 MHz RF cavity. A prototype has been built and operation is starting. Electron bunches 25 to 100 ps wide containing a charge up to 10 nC are expected to be delivered at an energy of 1 to 1.5 MeV. Extensive beam dynamics simulations have been made to predict the injector response. Beside the well-known PARMELA code, a locally developed code, ATHOS, as well as codes developed at Limeil (MATISSE and VLAMINCK), at Orsay (OAK, PRIAM) and Ecole Polytechnique were used. In spite of the specificity and limitations inherent to each code, an overall agreement within 20% is obtained for the main beam characteristics. It is shown that for intense short bunches, the space charge induced correlated emittance growth can be controlled by a magnetic lens

  1. An electron gun with replaceable cathode-heater assembly for an E-beam irradiator%可更换阴极热子的辐照加速器用电子枪

    Institute of Scientific and Technical Information of China (English)

    吴迅雷; 于晓娟; 蒋振柏

    2011-01-01

    A new type of electron guns has been developed for a 10 MeV 1.5 mA linac for radiation processing. The specifications required are: cathode voltage 60 kV, peak beam current 550-600 mA, spot size 4 mm, and working distance 60 mm. Particularly, this electron gun is advantageous in its replaceable cathode-heater assembly. This helps the customers to reduce their operation cost. The Egun and Mafia codes were used to simulate electromagnetic fields and electron trajectories. The guns were produced in the same technology of our klystron production. Design specifications of the gun were achieved in the beam current test and beam spot test. The first gun of this type has been working on an linac for about 3000 hours.%本文介绍了工作电压为60 kV、峰值电流为550-600 mA、射程要求为60 mm、注腰不大于Φ4 mm的电子枪的研制.该电子枪用于辐射加工电子直线加速器(10 MeV 1.5 mA).为降低加速器的运营成本,该电子枪特别设计为可更换阴极热子型.采用Egun、Mafia等软件进行模拟计算,基本按照速调管生产的工艺流程,制成该电子枪.热测及束斑测试表明,该电子枪各项参数均达用户要求,目前已在加速器上正常运行约3000 h.

  2. 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…

  3. 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.

  4. A self-adaptive feedforward rf control system for linacs

    International Nuclear Information System (INIS)

    The design and performance of a self-adaptive feedforward rf control system are reported. The system was built for the linac of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory. Variables of time along the linac macropulse, such as field or phase are discretized and represented as vectors. Upon turn-on or after a large change in the operating-point, the control system acquires the response of the system to test signal vectors and generates a linearized system response matrix. During operation an error vector is generated by comparing the linac variable vectors and a target vector. The error vector is multiplied by the inverse of the system's matrix to generate a correction vector is added to an operating point vector. This control system can be used to control a klystron to produce flat rf amplitude and phase pulses, to control a rf cavity to reduce the rf field fluctuation, and to compensate the energy spread among bunches in a rf linac. Beam loading effects can be corrected and a programmed ramp can be produced. The performance of the control system has been evaluated on the control of a klystron's output as well as an rf cavity. Both amplitude and phase have been regulated simultaneously. In initial tests, the rf output from a klystron has been regulated to an amplitude fluctuation of less than ±0.3% and phase variation of less than ±0.6deg. The rf field of the ATF's photo-cathode microwave gun cavity has been regulated to ±5% in amplitude and simultaneously to ±1deg in phase. Regulating just the rf field amplitude in the rf gun cavity, we have achieved amplitude fluctuation of less than ±2%. (orig.)

  5. The ALS Gun Electronics system

    International Nuclear Information System (INIS)

    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

  6. Simulations of Gaussian electron guns for RHIC electron lens

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-02-28

    Simulations of two versions of the electron gun for RHIC electron lens are presented. The electron guns have to generate an electron beam with Gaussian radial profile of the electron beam density. To achieve the Gaussian electron emission profile on the cathode we used a combination of the gun electrodes and shaping of the cathode surface. Dependence of electron gun performance parameters on the geometry of electrodes and the margins for electrodes positioning are presented.

  7. Simulations of Gaussian electron guns for RHIC electron lens

    International Nuclear Information System (INIS)

    Simulations of two versions of the electron gun for RHIC electron lens are presented. The electron guns have to generate an electron beam with Gaussian radial profile of the electron beam density. To achieve the Gaussian electron emission profile on the cathode we used a combination of the gun electrodes and shaping of the cathode surface. Dependence of electron gun performance parameters on the geometry of electrodes and the margins for electrodes positioning are presented.

  8. Improved Dispenser Cathodes

    Science.gov (United States)

    Ives, R. Lawrence; Falce, Lou

    2006-01-01

    Variations in emission current from dispenser cathodes can be caused by variations in temperature and work function over the surface. This paper described research to reduce these variations using improved mechanical designs and controlled porosity cathodes made from sintered tungsten wires. The program goal is to reduce current emission variations to less than 5% over the surface of magnetron injection guns operating temperature limited.

  9. Development of an electron gun for the KEK positron generator

    International Nuclear Information System (INIS)

    In the KEK Positron Generator, a semi-long pulsed beam (∼40ns) has turned out to be suitable for effective positron injection into the PF storage ring. However, to use the semi-long pulsed beam, there was a problem concerning the cathode lifetime of the gun. Thus, a new gun has been developed with a dispenser cathode, Y-796(EIMAC); the characteristics of this gun have been investigated. This new gun has been used since October 1988 and has continued to produce constant current of about 12A without having to exchange its cathode. Thus, the cathode lifetime has been remarkably improved. (author) 6 refs., 7 figs

  10. Growth of cerium oxide thin layers for the manufacture of dosemeters and/or irradiation detectors by magnetron RF cathodic sputtering

    International Nuclear Information System (INIS)

    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 CeO2 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 CeO2 thin films. (O.M.)

  11. Advances in DC photocathode electron guns

    International Nuclear Information System (INIS)

    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

  12. Advances in DC photocathode electron guns

    International Nuclear Information System (INIS)

    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

  13. Advances in DC photocathode electron guns

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. RF properties at 6 GHz of ultra-high vacuum cathodic arc films up to 450 oersted

    International Nuclear Information System (INIS)

    Several films of niobium were deposited on copper plates via the ultra-high vacuum cathodic arc (UHVCA) deposition method as described by R. Russo et al. [R. Russo et al., Supercond. Sci. Tech. 18 (2005) L41; R. Russo et al., J. Appl. Phys., submitted for publication]. We attached these end plates to a 6 GHz cavity operating in the TE011 mode for characterizing the film quality by measuring the Q versus surface magnetic field

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

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, J., E-mail: julian.fischer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Adelhelm, C.; Bergfeldt, T. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chang, K. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 46 52074 Aachen (Germany); Ziebert, C.; Leiste, H.; Stüber, M.; Ulrich, S. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Music, D.; Hallstedt, B. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 46 52074 Aachen (Germany); Seifert, H.J. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2013-01-01

    Today most commercially available lithium ion batteries are still based on the toxic and expensive LiCoO{sub 2} as a standard cathode material. However, lithium manganese based cathode materials are cheaper and environmentally friendlier. In this work cubic-LiMn{sub 2}O{sub 4} spinel, monoclinic-Li{sub 2}MnO{sub 3} and orthorhombic-LiMnO{sub 2} thin films have been synthesized by non-reactive r.f. magnetron sputtering from two ceramic targets (LiMn{sub 2}O{sub 4}, LiMnO{sub 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{sub 2} by r.f. magnetron sputtering in combination with post-annealing ► Discharge capacity with o-LiMnO{sub 2} cathodes twice as high as for c

  17. 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)

    Today most commercially available lithium ion batteries are still based on the toxic and expensive LiCoO2 as a standard cathode material. However, lithium manganese based cathode materials are cheaper and environmentally friendlier. In this work cubic-LiMn2O4 spinel, monoclinic-Li2MnO3 and orthorhombic-LiMnO2 thin films have been synthesized by non-reactive r.f. magnetron sputtering from two ceramic targets (LiMn2O4, LiMnO2) 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-LiMnO2 by r.f. magnetron sputtering in combination with post-annealing ► Discharge capacity with o-LiMnO2 cathodes twice as high as for c-LiMn2O4 ► Thin film deposition of m-Li2MnO3 and o-LiMnO2

  18. Numerical modelling of the CEBAF electron gun with EGUN

    International Nuclear Information System (INIS)

    The electron source used in the injector for the CEBAF accelerator is a Hermosa electron gun with a 2 mm diameter cathode and a control electrode. It produces a 100 keV electron beam to be focused on the first of two apertures which comprise an emittance filter. A normalized emittance of less than π mm mrad at 1.2 mA is set by the requirements of the final beam from the CEBAF linac, since downstream of the filter, a system of two choppers and a third aperture removes 5/6 of the current. In addition, for RF test purposes a higher current of about 5 mA is needed, possibly at higher emittance. This paper presents a way of calculating the characteristics of the CEBAF electron gun with the gun design code EGUN, and the accuracy of the results is discussed. The transverse shape of the beam delivered by the gun has been observed, and its current measured. A halo around the beam has been seen, and the calculations can reproduce this effect

  19. Electron gun for technological linear accelerator

    International Nuclear Information System (INIS)

    The work is purposed to the design of diode electron gun for powerful technologic electron linac and to experimental investigations of the beam parameters at the gun exit.The gun feature is the quick cathode replacement.This is very impotent for operating of the accelerator.The gun optics and beam parameters were calculated using the EGUN code.Beam parameters were investigated as at the special test stand so as component of the linac injector.The gun produces the beam current of 2 A at the anode voltage 25 kV.Measured beam parameters correspond to calculated results

  20. State-of-the-air electron guns and injector designs for Energy Recovery Linacs (ERL)

    International Nuclear Information System (INIS)

    A key technology issue of energy recovery linac (ERL) devices for high-power free-electron laser (FEL) and fourth generation light sources is the demonstration of reliable, high-brightness, high-power injector operation. Three ongoing programs that target up to 0.5 Ampere photocathode injector performance with required ERL brightness, are described. The first is a DC gun and superconducting RF (SRF) booster cryomodule. Such a 748.5 MHz device is being assembled and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility (JLAB) beginning in 2006. The second approach is a high-current normal-conducting RF (NCRF) injector. A 700 MHz gun will undergo thermal test in late 2005 at the Los Alamos National Laboratory (LANL), which when equipped with a suitable cathode, would be capable of exceeding 0.5 Ampere operation. Finally, a half-cell 703.75 MHz SRF gun with a diamond amplifier and other cathodes, will be tested to 0.5 Ampere at the Brookhaven National Laboratory (BNL) in 2007. The status and projected performance for each of these injector projects is presented.

  1. 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.

  2. A Gridded Electron Gun for a Sheet Beam Klystron

    International Nuclear Information System (INIS)

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

  3. A Gridded Electron Gun for a Sheet Beam Klystron

    Science.gov (United States)

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

    2003-12-01

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

  4. 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 ...

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

    International Nuclear Information System (INIS)

    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. High Peak Power Gyroklystron with an Inverted Magnetron Injection Gun

    Science.gov (United States)

    Read, Michael; Neilson, Jeff; Borchard, Philipp; Ives, Lawrence; Lawson, Wes

    2006-01-01

    This paper describes the design of a 25 MW, 30 GHz gyroklystron amplifier based on a coaxial RF structure. The design includes an inverted magnetron injection gun (MIG) for positioning and cooling the inner conductor. The gun produces a very low spread beam that contributes to a device efficiency of 54%. Details are given of the gun, RF structure, input and output couplers and collector.

  7. Gun Control

    OpenAIRE

    Moore, Mark; Cook, Phil; Braga, Anthony

    2001-01-01

    The purpose of this essay is to provide a foundation for understanding the "Great American Gun War," and to consider the next steps that could be taken in the search for an effective gun-control policy. We begin with a review of the more-or-less uncontroversial facts about trends in gun ownership and use, and the reasons why Americans are inclined to arm themselves. A discussion follows of the more contentious issues, whether and how guns influence levels or seriousness of crime. We then iden...

  8. Photo-cathode preparation system of the A0 photo-injector

    Energy Technology Data Exchange (ETDEWEB)

    Moyses Kuchnir et al.

    2002-08-23

    The A0 Photo-Injector is an electron accelerator located in the AZero high bay area of Fermilab. A pulsed laser system generates electron bunches by the photo-electric effect when hitting a photo-cathode in a 1.5-cell, 1.3 GHz RF gun. A 9-cell, 1.3 GHz superconducting resonant cavity then accelerates the electrons to 15 MeV. The 10 ps time resolved waveform of the laser pulses is transferred to the electron bunches. This report is focused on the first hardware component of this accelerator, the Photo-cathode Preparation System. The reason for its existence is in the nature of the photo-electric material film used: Cs{sub 2}Te (Cesium Telluride), a very reactive compound that once coated on the cathode requires that it be transported and used in ultra high vacuum (UHV), i.e. < 10{sup -9} Torr.

  9. 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...

  10. 基于大功率电子枪的阴极加热控制系统的设计%Design of Cathode heating System for High-Power Electronic Beam Gun

    Institute of Scientific and Technical Information of China (English)

    陆幼青; 郭光耀; 左从进

    2012-01-01

    The heated cathode of the electron beam gun was used as a starting point. Compared with SCR control system applying single-phase AC circuit to regulate voltage. The design of high-power switching power supply was made based on chip SG3525 instead of the traditional method. The stable output was got by using the pulse-width modulation and the requested heating current would have been adjusted manually. The result of the experiment shows that the power system always has good characteristics such as easier to control, higher current, and lower voltage as well as faster speed.%以电子枪阴极灯丝加热电流为研究对象,建立一套可靠、稳定的阴极加热控制系统.相对于传统采用可控硅控制的单相交流调压电路,该电源的设计基于PWM电流控制芯片SG3525,采用恒频脉宽调制控制方式,自动调整输出功率得到稳定的电流输出.充分满足了阴极灯丝所需的低电压、大电流、加热速度快的特性要求.

  11. 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.

  12. Electron Gun For a High-Power X-Band Magnicon Amplifier

    Science.gov (United States)

    Yakovlev, V. P.; Nezhevenko, O. A.; True, R.

    1997-05-01

    This paper describes a 500 kV, 210 amp, advanced Pierce gun for a high power, 11.4 GHz, 60% efficient, second harmonic magnicon amplifier. This magnicon, being developed jointly by a collaboration of workers from Omega-P, NRL, and Litton, represents a prototype RF power source for future linear colliders. High magnicon efficiency requires use of a small diameter electron beam. From a 7.5 cm diameter low temperature dispenser cathode, the diameter of the focussed beam is 1.5 mm in a 0.65 T main field. In this case, beam area compression is 2500:1, and beam energy density is over 10 kJ/cm^2 per pulse. A unique feature of the gun is that the focus electrode is electrically isolated from the cathode. This not only help in achievement of the high beam intensity, it eliminates emission from the side of the cathode which is often the major ultimate origin of beam halo.

  13. Long pulse electron gun for laser applications

    International Nuclear Information System (INIS)

    This paper reports on large-area electron guns that are critical components in many high-energy gas laser systems. The secondary emission electron (SEE) gun offers an attractive option for pulsed laser applications. With this type of cold cathode gun, a dc voltage is applied to the cathode and the electron beam is generated by secondary emission due to ion bombardment processes. The gun is controlled by modulating the source of ions which resides at ground potential. This design greatly simplifies the electron gun power system. SEE-gun systems have been developed which provide 150-220 keV beams at current densities exceeding 25 mA/cm2 with current density uniformities of approximately ±10% over areas of up to 5 x 150 cm2. Pulse lengths have ranged from 30 μs to 20 ms at repetition rates from single-pulse to 30 Hz. It is expected that the SEE-gun can be scaled to beam voltages of greater than 300 kV, beam areas greater than 1 m2, peak current densities exceeding 1 A/cm2, time-averaged current densities approx-gt 0.5 mA/cm2, pulse lengths of 0.1 μs to dc, and pulse repetition rates >1 kHz with good uniformity, high reliability and long life. Furthermore, the inherent simplicity of the SEE-gun results in low cost and a compact, light-weight system

  14. 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)

  15. 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...

  16. Development of laser heated high current DC electron gun

    International Nuclear Information System (INIS)

    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, LaB6 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 LaB6 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 LaB6 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 LaB6 cathode. The perveance obtained is 7.1 x 10-8 A/V3/2 . 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)

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

    Science.gov (United States)

    Iqbal, Munawar; Fazal-e-Aleem

    2006-10-01

    We describe new features and results from the previously reported [M. Iqbal et al., Rev. Sci. Instrum. 74, 4616 (2003)] thermionic long (up to 140mm) cathode, electromagnetically focused electron beam gun. The gun which was tested up to 50kW (5000mA×10kV) achieves power density of 33kW/cm2 at the target. The cathode temperature and emission current was uniform over a length of 100mm 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.

  18. 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.

  19. Spectrometer gun

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    Huang, R.; Filippetto, D.; Papadopoulos, C. F.; Qian, H.; Sannibale, F.; Zolotorev, M.

    2015-01-01

    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.

  1. A high-brightness thermionic microwave electron gun

    International Nuclear Information System (INIS)

    In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun's performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ''State-of-the-art'' microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of ec · μm for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread ±10%. These emittances are for up to 5 x 109e- per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically e · μm

  2. ECR ion source with electron gun

    Science.gov (United States)

    Xie, Zu Q.; Lyneis, Claude M.

    1993-01-01

    An Advanced Electron Cyclotron Resonance ion source (10) having an electron gun (52) for introducing electrons into the plasma chamber (18) of the ion source (10). The ion source (10) has a injection enclosure (12) and a plasma chamber tank (14). The plasma chamber (18) is defined by a plurality of longitudinal magnets (16). The electron gun (52) injects electrons axially into the plasma chamber (18) such that ionization within the plasma chamber (18) occurs in the presence of the additional electrons produced by the electron gun (52). The electron gun (52) has a cathode (116) for emitting electrons therefrom which is heated by current supplied from an AC power supply (96) while bias potential is provided by a bias power supply (118). A concentric inner conductor (60) and Outer conductor (62) carry heating current to a carbon chuck (104) and carbon pusher (114) Which hold the cathode (116) in place and also heat the cathode (16). In the Advanced Electron Cyclotron Resonance ion source (10), the electron gun (52) replaces the conventional first stage used in prior art electron cyclotron resonance ion generators.

  3. Planar Ultrananocrystalline Diamond Field Emitter in Accelerator RF Electron Injector: Performance Metrics

    CERN Document Server

    Baryshev, Sergey V; Shao, Jiahang; Jing, Chunguang; Quintero, Kenneth J Pérez; Qui, Jiaqi; Liu, Wanming; Gai, Wei; Kanareykin, Alexei D; Sumant, Anirudha V

    2014-01-01

    A case performance study of a planar field emission cathode (FEC) based on nitrogen-incorporated ultrananocrystalline diamond, (N)UNCD, was carried out in an RF 1.3 GHz electron gun. The FEC was a 100 nm (N)UNCD film grown on a 20 mm diameter stainless steel disk with a Mo buffer layer. At surface gradients 45-65 MV/m, peak currents of 1-80 mA (equivalent to 0.3-25 mA/cm$^2$) were achieved. Imaging with two YAG screens confirmed emission from the (N)UNCD surface with (1) the beam emittance of 1.5 mm$\\times$mrad/mm-rms, and (2) longitudinal FWHM and rms energy spread of 0.7% and 11% at an electron energy of 2 MeV. Current stability was tested over the course of 36$\\times$10$^3$ RF pulses (equivalent to 288$\\times$10$^6$ GHz oscillations).

  4. 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...

  5. Ion bombardment investigations of impregnated cathodes

    Science.gov (United States)

    Zhang, Xiaobing; Gaertner, Georg

    2003-06-01

    Ion bombardment is one of the important factors limiting the performance of impregnated cathodes (=Ba dispenser cathodes) in high end television tubes or in colour monitor tubes. Hence, when designing a new gun with, e.g. higher electron beam current density, it is important also to model the influence of ion bombardment. Therefore, relations between basic parameters as a function of temperature need to be known quantitatively. In this paper, the emission slump of impregnated cathodes has been analyzed in a diode configuration in UHV with a differentially pumped Ar ion gun. The emission degeneration during and regeneration periods after ion bombardment have been investigated as function of cathode temperature, ion current and ion energy. One of the important results is, that the degeneration time coefficient is only weakly dependent on ion energy. The data matrix obtained can be used to improve the ion bombardment model applied in new electron gun design.

  6. Ion bombardment investigations of impregnated cathodes

    International Nuclear Information System (INIS)

    Ion bombardment is one of the important factors limiting the performance of impregnated cathodes (=Ba dispenser cathodes) in high end television tubes or in colour monitor tubes. Hence, when designing a new gun with, e.g. higher electron beam current density, it is important also to model the influence of ion bombardment. Therefore, relations between basic parameters as a function of temperature need to be known quantitatively. In this paper, the emission slump of impregnated cathodes has been analyzed in a diode configuration in UHV with a differentially pumped Ar ion gun. The emission degeneration during and regeneration periods after ion bombardment have been investigated as function of cathode temperature, ion current and ion energy. One of the important results is, that the degeneration time coefficient is only weakly dependent on ion energy. The data matrix obtained can be used to improve the ion bombardment model applied in new electron gun design

  7. High Power RF Conditioning and Measurement of Longitudinal Emittance at PITZ

    CERN Document Server

    Bähr, Jürgen; HuiHan, Jang; Krasilnikov, Mikhail; Lipka, Dirk; Miltchev, Velizar; Oppelt, Anne; Petrosyan, Bagrat; Pose, Dietrich; Riemann, S; Staykov, Lazar; Stephan, Frank

    2004-01-01

    In 2003 the PITZ RF-gun at DESY Zeuthen has been fully characterized. After RF conditioning 3.2MW input power at 10Hz and a RF-pulse length of 0.9ms has been reached. This correponds to a gradient of 42MV/m at the cathode. The goal is to increase the accelerating gradient of the gun and the duty cycle significantly. The motivation is based on the expectation of a remarkable increase in beam quality at higher gradients. A high duty cycle is of advantage for FEL users. The conditioning procedure was started in spring 2004. The paper will report about procedure and results of this program. The preparation of an experimental setup for the measurement of the complete longitudinal phase space at about 5 MeV using a streak camera will be finished in summer 2004. Cherenkov light created by Silica aerogel radiators in the dispersive arm of PITZ is transmitted to a streak camera by an optical transmission line. The light distribution of the momentum spectrum is projected onto the entrance slit of the streak camera. The...

  8. Development of beam diagnostic devices for characterizing electron guns

    International Nuclear Information System (INIS)

    The electron guns for the DC accelerators and RF Linacs are designed and developed at EBC/APPD/BARC, Kharghar. These electron guns need to be characterized for its design and performance. Two test benches were developed for characterizing the electron guns. Various beam diagnostic devices for measuring beam currents and beam sizes were developed. Conical faraday cup, segmented faraday cup, slit scanning bellows movement arrangement, multi-plate beam size measurement setup, multi- wire beam size measurement setup, Aluminum foil puncture assembly etc. were developed and used. The paper presents the in-house development of various beam diagnostics for characterizing electron guns and their use. (author)

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

    International Nuclear Information System (INIS)

    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

  10. Neutron gun

    International Nuclear Information System (INIS)

    The neutron gun combines a new core ion source of the cold type based on X-ray ionization and new cold type of neutron source working with core ion generation. The neutrons are formed from the impact of core ions on the negatively charged anode. Based on a new conversion function, the function of the positive anode becomes analogous to the beta-unstable decomposition of a neutron. A core ion and neutron amplifier in the sense of amplifying the number is derived from the beta-unstable neutron decomposition, in order to raise the output of a gun in pulsed operation by using the number amplification in the intervals between the pulses. The method of construction is simple and cheap, the equipment has purely linear acceleration or operation with circular acceleration with linear pre-acceleration as an alternative. Purely linear operation should be sufficient for medical applications, e.g. for neutron photography to replay X-ray photography and particularly for neutron scalpels in the surgical treatment of tumours. (orig./HP)

  11. Deposition of Ba.sub.x./sub.Sr.sub.1-x./sub.TiO.sub.3./sub. thin films by double RF hollow cathode plasma jet system

    Czech Academy of Sciences Publication Activity Database

    Hubička, Zdeněk; Virostko, Petr; Olejníček, Jiří; Deyneka, Alexander; Adámek, Petr; Valvoda, V.; Jastrabík, Lubomír; Šícha, Miloš; Tichý, M.

    Praha: Institute of Plasma Physics AS CR, 2007 - (Schmidt, J.; Šimek, M.; Pekárek, S.; Prukner, V.), 765-768 ISBN 978-80-87026-01-4. [International conference on phenomena in ionized gases - ICPIG /28./. Praha (CZ), 15.07.2007-20.07.2007] R&D Projects: GA AV ČR KAN301370701; GA AV ČR 1QS100100563; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : BSTO * thin films * plasma deposition * hollow cathode * plasma jet Subject RIV: BL - Plasma and Gas Discharge Physics

  12. Deposition of Ba.sub.x./sub.Sr.sub.1-x./sub.TiO.sub.3./sub. thin films by double RF hollow cathode plasma jet system

    Czech Academy of Sciences Publication Activity Database

    Hubička, Zdeněk; Virostko, Petr; Tichý, M.; Čada, Martin; Adámek, Petr; Olejníček, Jiří; Deyneka, Alexander; Churpita, Olexandr; Valvoda, V.; Jastrabík, Lubomír

    2008-01-01

    Roč. 48, 5-7 (2008), s. 515-520. ISSN 0863-1042 R&D Projects: GA AV ČR KAN301370701; GA AV ČR KJB100100707; GA AV ČR 1QS100100563; GA ČR GA202/06/0776 Institutional research plan: CEZ:AV0Z10100522 Keywords : BSTO * ferroelectric films * hollow cathode * Langmuir probe * optical emission spectroscopy * plasma jet Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.250, year: 2008

  13. 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…

  14. 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. PMID:26124073

  15. Construction of cathode thermometry and emission test system

    International Nuclear Information System (INIS)

    A thermal cathode (Eimac Y-845) is used for an electron gun at the SPring-8 1-GeV linac. The gun can eject a 180 keV beam of 3 A from the cathode operated at a nominal heater voltage. As the discharge rate between the cathode and the grid becomes high along with the cathode driving time, we replace a cathode with a new one once a year. Before the cathode installation, we have definitely inspected new cathodes by means of a microscope to find defects in their cathodes and grids. However, the emission currents have been sometimes insufficient, or the cathode planes have contacted with the grids due to the heat distortion of the grids. We have suspected that the inadequate cathode temperature may have caused these cathode failures. To monitor the accurate cathode temperature and to reduce the cathode failures, we have constructed a measuring system of the cathode temperatures and the cathode emission currents at the test stand. We redesigned the whenelt and the anode to achieve a space-charge-limited current of 3 A at an acceleration voltage less than -70 kV. The cathode temperature at the nominal heater voltage is expected to be 854degC according to the Richardson-Dushman equation, whereas the actual temperature measured by an infrared thermometer was 813±5degC. This large disagreement is under investigation. (author)

  16. Cyclotron resonance in a cathode ray tube

    International Nuclear Information System (INIS)

    Absorption of the RF energy by the electron beam in a cathode ray tube due to the cyclotron resonance is described. The cathode ray tube is placed within a Helmholtz coils system supplied by a sawtooth current generator. In order to generate RF field and to detect RF absorption a gate dip-meter equipped with a FET transistor is used. The bias voltage variations of the FET transistors as a function of the magnetic field are recorded. The operating point of the cathode ray tube has been chosen so that the relaxation oscillations of the detection system can be observed. (authors)

  17. Status of the Rand D Program at the Gun Test Facility

    International Nuclear Information System (INIS)

    The Gun Test Facility (GTF) consists of a 1.6-cell S-band photocathode gun and a single SLAC 3-m accelerating structure (booster) followed by a beam dump. The beam components are housed in the SPEAR synchrotron injector vault in Building 140. Outside the vault are the two XK5 klystrons/modulators that provide the rf power, and the laser shack and control area. The laser shack contains a high-power low repetition rate Nd:glass laser system used to produce photoelectrons from the copper cathode of the gun. Using an earlier (borrowed) version of the laser system, first beams were produced in 1997. Completion of installation and commissioning took place in 1998, and the first experimental results were obtained. In 1999, the laser system was completely replaced with a SLAC-owned, nearly duplicate, system. The purpose of the GTF from the start was to demonstrate and characterize the high-brightness beam required for the LCLS. The nominal LCLS beam at the booster exit is 1 nC of charge, 100 A, with an energy spread of (le)0.2% and a normalized rms emittance of 1 x 10-6 m. To achieve this emittance, the nominal plan is to use a charge distribution at the cathode that is spatially and temporally uniform, with 2-mm and 10-ps FWHM diameter and length respectively. The current LCLS RandD program was funded beginning in mid-FY99. From the start it was determined by the LCLS Project leaders that the GTF was the appropriate facility for conducting the injector RandD

  18. A new dispenser cathode with dual-layer

    Science.gov (United States)

    Li, Yutao; Zhang, Honglai; Liu, Pukun; Zhang, Mingchen

    2005-09-01

    The emission and surface characteristics of the dispenser cathode coated with Os-W alloy and that coated with Os-W/Re are studied and compared. The dispenser cathode coated with Os-W/Re has been applied in electron gun measurement system for making measurement of higher emission current and life test. We called the cathode coated with Os-W/Re as the cathode with dual-layer. It is found that the dispenser cathode coated with dual-layer has higher current density than that coated only with Os-W alloy. After being activated, the cathode coated with dual-layer presents ternary composition on the surface of it. The W surface composition does not rise with time comparing with that of the cathode coated with Os-W alloy. In electron gun, the dispenser cathode coated with dual-layer has pulse current density of 30 A/cm 2 and life of more than 800 h.

  19. A new dispenser cathode with dual-layer

    International Nuclear Information System (INIS)

    The emission and surface characteristics of the dispenser cathode coated with Os-W alloy and that coated with Os-W/Re are studied and compared. The dispenser cathode coated with Os-W/Re has been applied in electron gun measurement system for making measurement of higher emission current and life test. We called the cathode coated with Os-W/Re as the cathode with dual-layer. It is found that the dispenser cathode coated with dual-layer has higher current density than that coated only with Os-W alloy. After being activated, the cathode coated with dual-layer presents ternary composition on the surface of it. The W surface composition does not rise with time comparing with that of the cathode coated with Os-W alloy. In electron gun, the dispenser cathode coated with dual-layer has pulse current density of 30 A/cm2 and life of more than 800 h

  20. 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)

  1. Improved DC Gun and Insulator Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, Michael; Johnson, Rolland P

    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.

  2. 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 ...

  3. Pulsed electron gun and linear accelerator fitted with such a gun

    International Nuclear Information System (INIS)

    This invention relates to a pulsed electron gun comprising a leak-tight insulating tube closed at one end. A voltage of several tens of kilovolts is applied by cables to the ends of the tube. Among its other features this gun includes a conducting tube fitted inside an insulating tube on the same centre line, in a leak-tight manner to it. This conducting tube forms the grid support, and the bottom of the well so formed being closed by a conducting plate insulated from the conducting tube by an insulating ring, this plate becomes the support of the gun cathode. The grid support is part of the vacuum containment so formed. The electron linear accelerator comprising such a pulsed electron gun is also described

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

    Science.gov (United States)

    Han, Jang-Hui; Cox, Matthew; Huang, Houcheng; Pande, Shivaji

    2011-08-01

    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.

  5. R and D ERL: Low level RF

    International Nuclear Information System (INIS)

    A superconducting RF (SRF) Energy Recovery Linac (ERL) is currently under development at the Collider-Accelerator Department (C-AD) at Brookhaven National Laboratory (BNL). The major components from an RF perspective are (a) a 5-cell SRF ERL cavity, (b) an SRF photocathode electron gun, and (c) a drive laser for the photocathode gun. Each of these RF subsystems has its own set of RF performance requirements, as well as common requirements for ensuring correct synchronism between them. A low level RF (LLRF) control system is currently under development, which seeks to leverage both technology and experience gained from the recently commissioned RHIC LLRF system upgrade. This note will review the LLRF system requirements and describe the system to be installed at the ERL.

  6. Microcomputer based ship-board gun control system.

    OpenAIRE

    Erdogan, Ahmet

    1981-01-01

    Approved for public release; distribution is unlimited This study was undertaken to design and implement a microcomputer based gun control and interactive display system which is suitable as a model of a shipboard Gun Fire Control System and Tactical-Situation display. The stand-alone system includes two plasma display scopes, a microcomputer, a cathode ray tube (CRT), an analog-to-digital, digital-to-analog (ADC/DAC) board and a servo unit. The scope of the effort includes, calculation ...

  7. Self-bunching electron guns

    CERN Document Server

    Mako, F; Weilhammer, Peter

    1999-01-01

    We report on three electron gun projects that are aimed at power tube and injector applications. The purpose of the work is to develop robust electron guns which produce self-bunched, high-current-density beams. We have demonstrated cold emission, long life, and tolerance to contamination. The cold emission process is based on secondary electron emission. FMT has studied this resonant bunching process which gives rise to high current densities (0.01-5 kA/cm/sup 2/), high charge bunches (up to 100 nC/bunch), and short pulses (1-100 ps) for frequencies from 1 to 12 GHz. The beam pulse width is nominally ~5% of the RF period. The first project is the L-Band Micro-Pulse Gun (MPG). Measurements show ~40 ps long microbunches at ~20 A/cm/sup 2/ without contamination due to air exposure. Lifetime testing has been carried out for about 18 months operating at 1.25 GHz for almost 24 hours per day at a repetition rate of 300 Hz and 5 mu s-long macro- pulses. About 5.8*10/sup 13/ micro-bunches or 62,000 coulombs have pass...

  8. Multi-harmonic RF test stand for RF breakdown studies

    International Nuclear Information System (INIS)

    A multi-harmonic RF test stand is under construction at Yale Beam Physics Laboratory. It includes a frequency multiplier which can generate high power harmonics efficiently that are phase locked to the fundamental drive frequency. In a bi-modal asymmetric cavity powered by this RF source, the cavity may experience reduced exposure time to peak fields and sweeping of peak fields across their surfaces, and strong asymmetry between surfaces that may experience cathode-and anode-like fields; these phenomena are to be assessed for their influence on RF breakdown probabilities.

  9. Development of the Antares electron gun

    International Nuclear Information System (INIS)

    Antares is the Los Alamos National Laboratory 40-kJ, 1-ns, CO2 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 m2; 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

  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. Gun Safety (For Kids)

    Science.gov (United States)

    ... though guns are featured in many television shows, video games, computer games, and movies, it's important to know ... could only happen on TV, in movies, or video games. A real gun is never a toy, and ...

  12. Electron gun for SSRF

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A 100 kV triode-electron-gun has been designed and manufactured for the Linac of Shanghai Synchrotron Radiation Facility (SSRF). In this paper the performance of the gun and some key components are described.

  13. Study on ion induced secondary emission electron gun

    International Nuclear Information System (INIS)

    A low energy (2 is obtained in pulse width duration of 20 μs over an area of 64.5 cm2 at cathode voltage of 100 kV. The achieved combination of parameters (effective secondary emission coefficient γ' = 6.36, foil window transparency τ = 0.49, gun efficiency η = 33% and average power Pav = 230 W) are attractive to use the gun in various applications requiring a large cross-section electron beam. The utilization of the gun in the electron beam induced flue gas (NOx) treatment is underway. (author)

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

    International Nuclear Information System (INIS)

    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)

  15. A Robust High Current Density Electron Gun

    Science.gov (United States)

    Mako, F.; Peter, W.; Shiloh, J.; Len, L. K.

    1996-11-01

    Proof-of-principle experiments are proposed to validate a new concept for a robust, high-current density Pierce electron gun (RPG) for use in klystrons and high brightness electron sources for accelerators. This rugged, long-life electron gun avoids the difficulties associated with plasma cathodes, thermionic emitters, and field emission cathodes. The RPG concept employs the emission of secondary electrons in a transmission mode as opposed to the conventional mode of reflection, i.e., electrons exit from the back face of a thin negative electron affinity (NEA) material, and in the same direction as the incident beam. Current amplification through one stage of a NEA material could be over 50 times. The amplification is accomplished in one or more stages consisting of one primary emitter and one or more secondary emitters. The primary emitter is a low current density robust emitter (e.g., thoriated tungsten). The secondary emitters are thin NEA electrodes which emit secondary electrons in the same direction as the incident beam. Specific application is targeted for a klystron gun to be used by SLAC with a cold cathode at 30-40 amps/cm^2 output from the secondary emission stage, a ~2 μs pulse length, and ~200 pulses/second.

  16. Therminoic gun control system for the CEBAF injector

    International Nuclear Information System (INIS)

    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

  17. Hollow cathode startup using a microplasma discharge

    Science.gov (United States)

    Aston, G.

    1981-01-01

    Attention is given to a microplasma discharge to initiate a hollow cathode discharge for such applications as plasma flow experiments, the electric propulsion of space vehicles, and as a replacement for filament cathodes in neutral beam injector ion sources. The technique results in a cathode that is easy to start, simple in design, and which does not require external RF exciters, inserts or heating elements. Future applications may include ion beam milling and ion implantation.

  18. Self-bunching electron guns

    International Nuclear Information System (INIS)

    We report on three electron gun projects that are aimed at power tube and injector applications. The purpose of the work is to develop robust electron guns which produce self-bunched, high-current-density beams. We have demonstrated cold emission, long life, and tolerance to contamination. The cold emission process is based on secondary electron emission. FMT has studied this resonant bunching process which gives rise to high current densities (0.01-5 kA/cm2), high charge bunches (up to 100 nC/bunch), and short pulses (1-100 ps) for frequencies from 1 to 12 GHz. The beam pulse width is nominally ∼5% of the rf period. The first project is the L-Band Micro-Pulse Gun (MPG). Measurements show ∼40 ps long micro-bunches at ∼20 A/cm2 without contamination due to air exposure. Lifetime testing has been carried out for about 18 months operating at 1.25 GHz for almost 24 hours per day at a repetition rate of 300 Hz and 5 μs-long macro-pulses. About 5.8x1013 micro-bunches or ∼62,000 coulombs have passed through this gun and it is still working fine. The second project, the S-Band MPG†, is now operational. It is functioning at a frequency of 2.85 GHz, a repetition rate of 30 Hz, with a 2 μs-long macro-pulse. It produces about 150 A/cm2. The third project involves the construction of a 34.2 GHz frequency-multiplied source driven by an X-Band MPG. Analytical work has been carried out on this device, and we are ready to proceed with design, fabrication, and testing

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Work function measurements of dispenser cathodes by retarding potential method

    Science.gov (United States)

    Khairnar, Rajendra S.; Chopra, A. K.

    1992-11-01

    The work function of dispenser cathode pellets has been determined by means of the retarding potential technique. A low-energy electron gun was fabricated which delivers a collimated beam of electrons on the pellet surface at normal incidence. The set up is calibrated by employing samples of known work function such as gold and tungsten, prior to determining the work function of the cathode pellets. This set up provides a rapid determination of the work function of cathode pellets.

  1. 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.

  2. 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.

  3. 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,…

  4. ELECTROSTATIC MODELING OF THE JEFFERSON LABORATORY INVERTED CERAMIC GUN

    Energy Technology Data Exchange (ETDEWEB)

    P. Evtushenko ,F.E. Hannon, C. Hernandez-Garcia

    2010-05-01

    Jefferson Laboratory (JLab) is currently developing a new 500kV DC electron gun for future use with the FEL. The design consists of two inverted ceramics which support a central cathode electrode. This layout allows for a load-lock system to be located behind the gun chamber. The electrostatic geometry of the gun has been designed to minimize surface electric field gradients and also to provide some transverse focusing to the electron beam during transit between the cathode and anode. This paper discusses the electrode design philosophy and presents the results of electrostatic simulations. The electric field information obtained through modeling was used with particle tracking codes to predict the effects on the electron beam.

  5. 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.

  6. Simulation Study on the Emittance Compensation of Off-axis Emitted Beam in RF Photoinjector

    CERN Document Server

    Huang, Rui-Xuan; Jia, Qi-Ka; Papadopoulos, Christos; Sannibale, Fernando

    2016-01-01

    To make full use of photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent RF effect, which would generate a significant growth in transverse emittance. It has been demonstrated that such an emittance growth can be almost completely compensated by orienting the beam on a proper orbit in the downstream RF cavities along the injector. In this paper we analyze in detail the simulation techniques used in reference[1] and the issues associated with them. The optimization of photoinjector systems involving off-axis beams is a challenging problem. To solve this problem, one needs advanced simulation tools including both genetic algorithms and an efficient algorithm for 3D space charge. In this paper, we report on simulation studies where the two codes ASTRA and IMPACT-T are used jointly to overcome these challenges, in order to optimize a system designed to ...

  7. Construction of the 2nd 500kV DC gun at KEK

    International Nuclear Information System (INIS)

    The 2nd 500 kV DC photocathode electron gun for a ERL injector was constructed at KEK. The gun has some functions such as a insulated anode electrode for using dark current monitor, a repeller electrode for decreasing backward ions, extreme high vacuum pumps and so on. A high voltage conditioning is just begun from this summer. In addition, a new cathode preparation system has been developed. It can prepare three cathodes simultaneously and storage many cathodes in a good vacuum condition. The detail design was finished and the construction of all in-vacuum components is progressing. (author)

  8. RF transport

    OpenAIRE

    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.

  9. Emittance measurement for high-brightness electron guns

    International Nuclear Information System (INIS)

    An emittance measurement system based on a high-precision pepper-pot technique has been developed for electron guns with low emittance of around πmm-mrad. Electron guns with a 1 mmφ cathode, the material of which is impregnated tungsten or single-crystal lanthanum hexaboride (La1-xCex)B6, have been developed. The performance has been evaluated by putting stress on cathode roughness, which gives rise to an angular divergence, according to the precise emittance measurement system. A new type of cathode holder, which is a modified version of the so called Vogel type, was developed and the beam uniformity has been improved. (Author) 5 figs., tab., 9 refs

  10. GUNS BEFORE POLITICS

    OpenAIRE

    P.L. Moorcroft

    2012-01-01

    'What we must stop is a situation where the gun is a means of promotion, a machine gun a way of applying pressure, a tank becomes government policy.' This was the despairing cry of an African lawyer during yet another recent military intervention in that most coup-ridden of African states, Dahomey.

  11. GUNS BEFORE POLITICS

    Directory of Open Access Journals (Sweden)

    P.L. Moorcroft

    2012-02-01

    Full Text Available 'What we must stop is a situation where the gun is a means of promotion, a machine gun a way of applying pressure, a tank becomes government policy.' This was the despairing cry of an African lawyer during yet another recent military intervention in that most coup-ridden of African states, Dahomey.

  12. Research and development of high-temperature operating photocathode electron source for high brightness electron gun

    International Nuclear Information System (INIS)

    We have been developing a novel photocathode RF gun system with an advanced RF cavity structure and a new photocathode material for the SuperKEKB electron linac. This injector is required to obtain a low emittance and high charge electron beams in order to achieve the highest luminosity in the world. The required beam parameters are 5 nC and 20 mm·mrad from the RF gun. Moreover, 10 nC electron beams for positron production will be also generated by the same RF gun. In order to obtain extremely high charge electron beams, Yb-based laser system is being upgraded for higher power and a high temperature photocathode system for a quantum efficiency (QE) enhancement will be introduced to the new RF gun system. This paper reports on the research and development of the system of high temperature photocathode for QE enhancement to be able to generate high charge electron beams (∼10 nC) at the RF gun in SuperKEKB electron linac. (author)

  13. RF system for quantum beam experiment and STF-2 in KEK-STF

    International Nuclear Information System (INIS)

    The Superconducting RF Test Facility (STF) accelerator at KEK was operated to generate X-ray with high brightness via inverse Compton scattering for the Quantum Beam project. Two different RF systems were constructed for STF accelerator and operated to feed its power to one RF-gun cavity and two superconducting cavities. During the experimental period, the various developments of RF system were conducted for International Linear Collider (ILC). In this report, the status of RF system for the Quantum Beam project and the result of radiation dose to Low-level RF system mounted in accelerator tunnel are described. Also, the RF system for STF-2 accelerator is mentioned. (author)

  14. Characteristics of electron gun used in the accelerator for customs inspection systems

    International Nuclear Information System (INIS)

    The author introduces the characteristics of the electron gun used in the 9 MeV traveling wave electron linear accelerator for fixed customs container inspection system. With the scan date cathode, the electron gun meets the accelerator characteristics with the whole system not needing high-temperature roasting to degas. The electron gun can work normally at a vacuum of about 10-5 Pa and can be reinstalled after exposure to air. In the accelerator, the electron gun emits a beam which strikes the target to produce an X-ray beam with a dosage rate of over 30 Gy/(min·m) and a beam focus spot of less than φ 2 mm. The EGUN code is used to simulate the structure and properties of the electron gun. The reference size debugging parameters for replacing the electron gun are given for assembly requirements

  15. RF control of ICR proton linac

    International Nuclear Information System (INIS)

    At the ICR Kyoto University, the proton linac has been developed. The RF high power is fed into the cavity from the klystron and the RF pulse width is 65 μsec. The RF amplitude and the phase in the cavity are affected by the beam loading and the pulse shape of the klystron cathode voltage. The fast RF stabilization system are required to accelerate the high beam stably. The stabilization system consists of the auto level control (ALC) and the phase locked loop (PLL). The designed band width is more than 1 MHz. The main modules of the circuit are the PIN diode attenuator, the fast phase detector, the phase shifter and the wideband feedback amplifier. The variation of the RF amplitude and the RF phase are 0.5 % with ALC and 5deg with PLL, respectively. (author)

  16. The Missing Gun The Missing Gun

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ma Shan, a criminal poljceman in a remotesmall town in the southwestern Yunnan province,gets drunk at his sister’s wedding and has his three-bullet gun lost, He tries to find it stealthily but endsup in vain. He has tno choice but to report the

  17. Study of electron current extraction from a radio frequency plasma cathode designed as a neutralizer for ion source applications

    Energy Technology Data Exchange (ETDEWEB)

    Jahanbakhsh, Sina, E-mail: sinajahanbakhsh@gmail.com; Satir, Mert; Celik, Murat [Department of Mechanical Engineering, Bogazici University, Istanbul 34342 (Turkey)

    2016-02-15

    Plasma cathodes are insert free devices that are developed to be employed as electron sources in electric propulsion and ion source applications as practical alternatives to more commonly used hollow cathodes. Inductively coupled plasma cathodes, or Radio Frequency (RF) plasma cathodes, are introduced in recent years. Because of its compact geometry, and simple and efficient plasma generation, RF plasma source is considered to be suitable for plasma cathode applications. In this study, numerous RF plasma cathodes have been designed and manufactured. Experimental measurements have been conducted to study the effects of geometric and operational parameters. Experimental results of this study show that the plasma generation and electron extraction characteristics of the RF plasma cathode device strongly depend on the geometric parameters such as chamber diameter, chamber length, orifice diameter, orifice length, as well as the operational parameters such as RF power and gas mass flow rate.

  18. Lake Wobegon's Guns: Overestimating Our Gun-Related Competences

    OpenAIRE

    Emily Stark; Daniel Sachau

    2016-01-01

    The Lake Wobegon Effect is a general tendency for people to overestimate their own abilities. In this study, the authors conducted a large, nationally-representative survey of U.S. citizens to test whether Americans overestimate their own gun-relevant personality traits, gun safety knowledge, and ability to use a gun in an emergency. The authors also tested how gun control attitudes, political identification, gender, and gun experience affect self-perceptions. Consistent with prior research o...

  19. Rarefaction wave gun propulsion

    Science.gov (United States)

    Kathe, Eric Lee

    A new species of gun propulsion that dramatically reduces recoil momentum imparted to the gun is presented. First conceived by the author on 18 March 1999, the propulsion concept is explained, a methodology for the design of a reasonable apparatus for experimental validation using NATO standard 35mm TP anti-aircraft ammunition is developed, and the experimental results are presented. The firing results are juxtaposed by a simple interior ballistic model to place the experimental findings into a context within which they may better be understood. Rarefaction wave gun (RAVEN) propulsion is an original contribution to the field of armament engineering. No precedent is known, and no experimental results of such a gun have been published until now. Recoil reduction in excess of 50% was experimentally achieved without measured loss in projectile velocity. RAVEN achieves recoil reduction by means of a delayed venting of the breech of the gun chamber that directs the high enthalpy propellant gases through an expansion nozzle to generate forward thrust that abates the rearward momentum applied to the gun prior to venting. The novel feature of RAVEN, relative to prior recoilless rifles, is that sufficiently delayed venting results in a rarefaction wave that follows the projectile though the bore without catching it. Thus, the projectile exits the muzzle without any compromise to its propulsion performance relative to guns that maintain a sealed chamber.

  20. 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...

  1. Multipacting simulation and test results of BNL 704 MHz SRF gun

    Energy Technology Data Exchange (ETDEWEB)

    Xu W.; Belomestnykh, S.; Ben-Zvi, I.; Cullen, C. et al

    2012-05-20

    The BNL 704MHz SRF gun has a grooved choke joint to support the photo-cathode. Due to the distortion of grooves at the choke joint during the BCP for the choke joint, several multipacting barriers showed up when it was tested with Nb cathode stalk at JLab. We built a setup to use the spare large grain SRF cavity to test and condition the multipacting at BNL with various power sources up to 50kW. The test is carried out in three stages: testing the cavity performance without cathode, testing the cavity with the Nb cathode stalk that was used at Jlab, and testing the cavity with a copper cathode stalk that is based on the design for the SRF gun. This paper summarizes the results of multipacting simulation, and presents the large grain cavity test setup and the test results.

  2. Electron gun operating by secondary emission under ionic bombardment

    International Nuclear Information System (INIS)

    The electron gun includes an ionization chamber adjacent to the high voltage chamber. In the common wall to the two chambers there is an extraction grid. Facing it, the ionization chamber includes a window, with a same form as the extraction grid, and with a thin metal film. High voltage chamber includes a cathode. In giving to the two grids the form of parallel homologous thin sheet, a masking effect and a focusing effect are got, which allow to increase the electron gun efficiency

  3. 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.

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

    International Nuclear Information System (INIS)

    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.

  5. Copter Gun Explorations.

    Science.gov (United States)

    Park, John C.

    1992-01-01

    Describes an investigation in which students predict and verify the effect that the number of clicks of a toy copter gun has on the height that the copter will attain. Provides follow-up questions for the students. (MDH)

  6. 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.

  7. Gun Safety (For Parents)

    Science.gov (United States)

    ... Reports? What to Say Vaccines: Which Ones & When? Smart School Lunches Emmy-Nominated Video "Cerebral Palsy: Shannon's ... If you do keep a gun in the house, it's vital to keep it out of sight ...

  8. 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 ...

  9. Calculating effective gun policies

    OpenAIRE

    Wodarz, Dominik; Komarova, Natalia L.

    2013-01-01

    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: either a ban of ...

  10. Air gun test facility

    International Nuclear Information System (INIS)

    This paper describes a facility that is potentially useful in providing data for models to predict the effects of nuclear explosions on cities. IIT Research Institute has a large air gun facility capable of launching heavy items of a wide variety of geometries to velocities ranging from about 80 fps to 1100 fps. The facility and its capabilities are described, and city model problem areas capable of investigation using the air gun are presented

  11. A ferroelectric electron gun in a free-electron maser experiment

    CERN Document Server

    Einat, M; Rosenman, G

    2002-01-01

    An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 mu s pulse width. The pulse repetition frequency attains 3.1 MHz in approx 50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices.

  12. Design of the electron gun for the INS-ES linac

    International Nuclear Information System (INIS)

    We are preparing a new electron gun for the INS-ES linac. Two cathode-wehnelt assemblies using dispenser cathode Y-646E (EIMAC) have been designed with the computer simulation program EGUN by W.B. Herrmannsfeldt. The acceleration voltage and the peak beam current is 100 kV and 1.0 A, respectively, with a pulse width of 1.5 μsec. The different point of the guns is the angle of wehnelt to the beam axis; one is 67.5deg and the other is 90deg. Both guns have almost the same beam characteristics: The beam radius is 1.95 mm and the maximum beam spread is 2.8 mrad at 186 mm from the cathode. (author)

  13. A 2-MeV microwave thermionic gun

    Science.gov (United States)

    Tanabe, E.; Borland, M.; Green, M. C.; Miller, R. H.; Nelson, L. V.; Weaver, J. N.; Wiedemann, H.

    1989-08-01

    A high gradient, S-band microwave gun with a thermionic cathode is being developed in a collaborative effort by AET, Varian, and SSRL. A prototype design using an upgraded Varian dispenser cathode mounted with thermal isolation directly in the first half-cell of a 1-1/2 cell, side coupled, standing-wave cavity was fabricated and is being tested. Optimization of the cavity shape and beam formation was done using SUPERFISH, MASK, and PARMELA. An overview of design details, as well as the status of in-progress beam tests, is presented.

  14. A 2-MeV microwave thermionic gun

    International Nuclear Information System (INIS)

    A high-gradient, S-band microwave gun with a thermionic cathode is being developed in a collaborative effort by AET, Varian, and SSRL. A prototype design using an upgraded Varian dispenser cathode mounted with thermal isolation directly in the first half-cell of a 1-1/2 cell, side-coupled, standing-wave cavity has been fabricated and is being tested. Optimization of the cavity shape and beam formation was done using SUPERFISH, MASK, and PARMELA. An overview of design details, as well as the status of in-progress beam tests, will be presented. 9 refs., 6 figs

  15. Development of a dust-free technique for a high-field photocathode DC electron gun

    International Nuclear Information System (INIS)

    In order to realize a high-brightness and monochromatic light source based on accelerator technologies, increasing of the cathode surface field of an electron gun is mandatory. Dust-free technique is a key technology to realize a high-field electron gun. We propose a new style dust-free technique. In this paper, R and D status and result of the preliminary test of the dust-free technique are reported. (author)

  16. A comparative study of PPM and solenoid focusing in multibeam electron gun

    International Nuclear Information System (INIS)

    This paper represents the comparison of periodic permanent magnet (PPM) and solenoid focusing for dual anode multi-beam electron gun using OPERA3D code. The electron gun has been operated at 6 kV having 75 mA beam current with 0.45 mm beam waist radius. The design has an additional feature of cathode protection from ion bombardment with the application of extra ion barrier anode.

  17. Modelling and simulation of beam formation in electron guns

    International Nuclear Information System (INIS)

    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.)

  18. 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...

  19. Diagnostic for a high-repetition rate electron photo-gun and first measurements

    Science.gov (United States)

    Filippetto, D.; Doolittle, L.; Huang, G.; Norum, E.; Portmann, G.; Qian, H.; Sannibale, F.

    2015-05-01

    The APEX electron source at LBNL combines the high-repetition-rate with the high beam brightness typical of photoguns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment, opening the doors of the high average power to brightness-hungry applications as X-Ray FELs, MHz ultrafast electron diffraction etc.. As first step, a complete characterization of the beam parameters is foreseen at the Gun beam energy of 750 keV. Diagnostics for low and high current measurements have been installed and tested, and measurements of cathode lifetime and thermal emittance in a RF environment with mA current performed. The recent installation of a double slit system, a deflecting cavity and a high precision spectrometer, allow the exploration of the full 6D phase space. Here we discuss the present layout of the machine and future upgrades, showing the latest results at low and high repetition rate, together with the tools and techniques used.

  20. Calculation of aberration of electron gun in color picture tubes

    International Nuclear Information System (INIS)

    In a color picture tube, aberration is an important factor influencing the electron beam spot on the screen. This paper discusses a new method which is used to calculate the aberration of an electron gun in a CPT. In this method, electron trajectories are simulated directly in the cathode and the pre-focus lens. In the main lens, the asymptotic aberration is calculated to decide the size of the image. Some results of the calculation are shown in this paper. (orig.)

  1. Brookhaven Accelerator Test Facility photocathode gun and transport beamline

    International Nuclear Information System (INIS)

    We present an analysis of the electron beam emitted from a laser driven photocathode injector (Gun, operating at 2856 MHZ), through a Transport beamline, to the LINAC entrance for the Brookhaven Accelerator Test Facility (ATF). The beam parameters including beam energy, and emittance are calculated. Some of our results, are tabulated and the phase plots of the beam parameters, from Cathode, through the Transport line elements, to the LINAC entrance, are shown

  2. 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

  3. Enhancing the brightness of high current electron guns

    International Nuclear Information System (INIS)

    Concepts such as the two-beam accelerator offer the possibility of translating pulsed power technology into a form useful to the design of high luminosity accelerators for high-energy physics applications. Realization of the promise of these concepts will require the design of electron guns which are optimized with respect to beam brightness at current levels of approximately 1 kA. Because high luminosity implies accelerator operation at high repetition rates, the high-current beam source must be designed so that the beam does not intercept the electrodes. In our investigations of electron gun configurations, we have found that the brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. To investigate the sensitivity of beam brightness to these factors in a manner suitable for modelling transient phenomena at the beam head, we have developed a Darwin approximation particle code, DPC. The main component in our experimental program is a readily modified electron gun that allows us to test many candidate cathode materials, types, and electrode geometries at field stresses up to 1 MW/cm. We have also developed several diagnostics suitable for measuring the brightness of intense, low-emittance beams

  4. Fueling by coaxial plasma guns

    International Nuclear Information System (INIS)

    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

  5. PHERMEX electron gun development

    International Nuclear Information System (INIS)

    The PHERMEX facility is a 50-MHz standing-wave linear accelerator. Electrons are injected, accelerated, and transported to a tungsten target where bremsstrahlung x rays are generated for flash radiography of hydrodynamic systems. The purpose of this article is to describe the progress of PHERMEX electron gun development. The goal of this program is to generate and transport a 200-ns, 1-MV, 1-kA electron beam into the first PHERMEX accelerating cavity. The standard gun is operated at a pulse voltage of 550 kV, which is the limit determined by internal breakdown of the vacuum insulator. This insulator has been redesigned, and the gun has been pulsed at 750 kV without internal breakdown. At present, the current output is not limited by voltage but by a phenomenon called pulse shortening, which occurs at a pulse voltage of approximately 650 kV. The phenomenon has been investigated and the results are presented

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

    International Nuclear Information System (INIS)

    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

  7. Guns and sleep

    OpenAIRE

    Quan SF

    2015-01-01

    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 t...

  8. Guns and votes

    OpenAIRE

    Bouton, Laurent; Conconi, Paola; Pino, Francisco; Zanardi, Maurizio

    2013-01-01

    Why are U.S. congressmen reluctant to support gun control regulations, despite the fact that most Americans are in favor of them? We argue that re-election motives can help explain why politicians often take a pro-gun stance against the interests of the majority of the electorate. We describe a model in which an incumbent politician must decide on a primary issue, which is more important to a majority of voters, and a secondary issue, which a minority cares more intensely about. We derive con...

  9. Glue Guns: Aiming for Safety

    Science.gov (United States)

    Roy, Ken

    2010-01-01

    While glue guns are very useful, there are safety issues. Regardless of the temperature setting, glue guns can burn skin. The teacher should demonstrate and supervise the use of glue guns and have a plan should a student get burned. There should be an initial first aid protocol in place, followed by a visit to the school nurse. An accident report…

  10. Study and characterization of dispenser cathode of 10 MeV Linac

    International Nuclear Information System (INIS)

    A dispenser cathode of pressed and sintered Ba-Ni powder is used as electron source in electron linac having 10 MeV beam energy and 10 kW beam power at RRCAT. This linac is planned for development of agricultural radiation processing facility. In this e-linac a triode type electron gun is used. This paper describes the cathode behavioural model during operation with addition of sparkle on materials characterization of diminished emission cathode surface. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Alicia Hofler, Pavel Evtushenko, Frank Marhauser

    2009-09-01

    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.

  12. 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.

  13. Gun control saves lives.

    Science.gov (United States)

    Matzopoulos, Richard

    2016-01-01

    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. PMID:27245735

  14. 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…

  15. Serbian society and gun culture

    Directory of Open Access Journals (Sweden)

    Cvetković Vladimir

    2006-01-01

    Full Text Available 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 Light Weapons survey conducted in 2004 in Serbia. The results were analyzed within the theoretical framework proposed in the first part of the paper.

  16. CAPE TOWN'S TIME-GUNS

    OpenAIRE

    Bisset, W. M.

    2012-01-01

    Although a great many articles have been written on the subject of Cape Town's noon gun (the. official terminology is 'time-gun') most of the writers 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 recorded. By 1807 a noon gun was fired regularly from the Imhoff Battery on the seaward side of the Castle.1 On 4 August 1902 the noon gun was fired from Lion Battery on Signal Hill for the first time.2 The batter...

  17. RF transformer

    Science.gov (United States)

    Smith, James L.; Helenberg, Harold W.; Kilsdonk, Dennis J.

    1979-01-01

    There is provided an improved RF transformer having a single-turn secondary of cylindrical shape and a coiled encapsulated primary contained within the secondary. The coil is tapered so that the narrowest separation between the primary and the secondary is at one end of the coil. The encapsulated primary is removable from the secondary so that a variety of different capacity primaries can be utilized with one secondary.

  18. Thermal analysis and structural Optimization of electron gun for traveling wave tube

    International Nuclear Information System (INIS)

    Steady-state and transient thermal analysis of electron gun for a Ka-band traveling wave tube are theoretically performed with a newly-developed 2 mm cathode model by ANSYS software. The heat flux vector chart and temperature distribution chart as well as warm-up time are also derived. The discrepancy of 2% between simulation results and test results, proves that the finite element method is feasible. The ultimate temperature reached by cathode, at given heater power, remarkably depends on the thermal conduction mechanism through cathode module. Based on the heat flux vector chart, the structure of cathode support sleeve with the highest flux is optimized. After optimization, the temperature of cathode increases 28 ℃ the highest temperature of electron gun increases 27 ℃ and the warm-up time of cathode reduces 40 s under the same given heater power. The optimized structure can effectively shorten the warm-up time of cathode by 33% and thus improve fast warm-up the performance of cathode, enhancing the rapid response capability of traveling wave tube. (authors)

  19. Dynamics of a coaxial plasma gun

    International Nuclear Information System (INIS)

    The dynamics of an ionizing wave in a coaxial plasma gun with an azimuthal bias magnetic field is analysed in a theoretical model. Only the radial dependence is treated and instead of including a treatment of the energy balance two separate physical assumptions are made. In the first case it is assumed that the total internal electric field is given by the critical ionization velocity condition and in the second that the ionization rate is constant. For consistency wall sheaths are assumed to match the internal plasma potential to that of the walls. On the basis of momentum and particle balance the radial dependence of the electron density, current density, electric field and drift velocity are found. An electron source is required at the cathode and the relative contribution from ionization within the plasma is deduced. The assumption that there are no ion sources at the electrodes leads to a restriction on the possible values of the axial electric field. (Auth.)

  20. Electron linear accelerator with synchronous power supply of a HF device and an electron gun

    International Nuclear Information System (INIS)

    The paper presents synchronous pulse power supply circuits of HF-generator and of the cathode of an electron gun of LUE-8/5 electron linear accelerator. Application of the given circuit of pulse power supply enables to reduce accelerator device dimensions. 1 fig

  1. Electromagnetic Guns versus Conventional Guns - a performance comparison

    OpenAIRE

    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 paper, an investigation is done for the expected performance increase due to the higher muzzle velocities in air defense applications using a parametric as well as a Monte-Carlo approach. The Mont...

  2. Prospects for deflagration guns

    International Nuclear Information System (INIS)

    Deflagration is a process of fluid expansion with energy addition. Its existence in plasma physics was first discovered in the back-strapped T-tube experiments. In the coaxial plasma gun configuration the operation can be simple and yet produce a clean, high density (5 x 1015 cm-3), and high kinetic energy (10 to 50 keV) collimated plasma beam. Plasma acceleration mechanism was thought to be driven by J x B force. Tapered electrodes have been used to obtain plasma beams. Scaling of the gun can be performed according to simple theory based on momentum and energy balance. Proposed plasma fueling and injection to magnetic fusion systems will be discussed

  3. Gun Attitudes and Fear of Crime.

    Science.gov (United States)

    Heath, Linda; Weeks, Kyle; Murphy, Marie Mackay

    1997-01-01

    Using three studies, examined the relationship between attitudes toward guns and fear of crime. Findings indicate a connection between fear of crime and attitudes toward guns: people higher in fear of crime favored gun control. Results also established a relationship between stereotypical beliefs about gun victims and support for gun control. (RJM)

  4. Friction in rail guns

    Science.gov (United States)

    Kay, P. K.

    1984-01-01

    The influence of friction is included in the present equations describing the performance of an inductively driven rail gun. These equations, which have their basis in an empirical formulation, are applied to results from two different experiments. Only an approximate physical description of the problem is attempted, in view of the complexity of details in the interaction among forces of this magnitude over time periods of the order of milisecs.

  5. Present status of design, installation and testing of electron gun and low energy beam transport line of electron Linac at VECC

    International Nuclear Information System (INIS)

    A key component of ANURIB (Advanced National Facility of Unstable and Rare Isotope Beams) project at VECC is a 2 mA, 30/50 MeV continuous-wave superconducting electron linear accelerator (e-Linac). The e-Linac has two sections - a 10 MeV Injector and an Accelerator section for further accelerating the beam to 30/50 MeV. The Injector comprises a 300 kV de thermionic electron gun with gridded cathode modulated at 650 MHz, low energy beam transport (LEBT) line and an injector cryo-module (ICM) that houses one 9-cell beta=1, 1.3 GHz niobium elliptical cavity. As an alternative to the 300 kV gun, a capture cryo-module (CCM) having two single-cell beta=1, 1.3 GHz niobium cavities that will allow the electron gun to be operated at 100 kV is also being developed. The CCM will pre-accelerate the beam from the gun prior to injection in the ICM. The e-Linac has been jointly designed with TRIUMF Canada. The ICM is being built by TRIUMF whereas the front-end of the injector is being built indigenously at VECC. Till the Rajarhat site for ANURIB is getting ready, an e-Linac test area is being setup at VECC Salt Lake campus. The Injector is being installed here and will be later moved to the new campus. The electron gun and several components of the LEBT line up to the CCM have been installed. Alignment and vacuum tests have also been completed. The LEBT line consists of steering magnets, solenoid magnets, diagnostics chamber and a room temperature 1.3 GHz buncher. Solenoid magnets are under fabrication and steering magnets have been procured. A dipole magnet and rf- deflector cavity for characterization of time structure of the beam has been designed and will be added to the LEBT line. In this report, the detail design of the various components and magnets along with present status of installation of the Injector will be presented. (author)

  6. Development of C-band deflector for slice emittance monitoring of new electron gun

    International Nuclear Information System (INIS)

    The advanced RF electron gun was installed for an electronic source of a high charge and a low emittance in KEK e+/e- Linac, and the sliced bunch monitor is needed to achieve the required emittance for the SuperKEKB injection. In the KEK-Linac, we are monitoring using a fluorescent plate on the beam line. It is possible to measure the projection emittance of the beam in this way, however it is not possible to measure the slice emittance. To develop an electron gun which can be generating a beam of super-low emittance corresponding to SuperKEKB, monitoring of the slice emittance is required. The slice of time direction on a beam can be acquired by measuring the beam sliced with the RF-deflector using a fluorescent plate. RF-deflector performance is square root of RF frequency, has developed a high-powered ones corresponding to 10 GeV beam using X-band frequency at near the end of KEK-Linac. However, because the beam energy is about 10 MeV at the RF gun exit, enough resolution is obtained even by low energy. So, we have developed a new low energy RF-deflector using C-band frequency. (author)

  7. CAPE TOWN'S TIME-GUNS

    Directory of Open Access Journals (Sweden)

    W.M. Bisset

    2012-02-01

    Full Text Available Although a great many articles have been written on the subject of Cape Town's noon gun (the. official terminology is 'time-gun' most of the writers 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 recorded. By 1807 a noon gun was fired regularly from the Imhoff Battery on the seaward side of the Castle.1 On 4 August 1902 the noon gun was fired from Lion Battery on Signal Hill for the first time.2 The battery was built because of fears of war with Russia and had been armed with two 9- inch Rifled Muzzle Loading guns by 1891. Lion Battery was remodelled in 1911.

  8. High Power Testing of an X-Band RF Gun

    Science.gov (United States)

    Le Sage, G. P.; Hartemann, F. V.; Luhmann, N. C., Jr.; Ho, C. H.; Lau, W. K.; Yang, T. T.; Hwang, J. Y.; Liu, Y. C.

    1997-05-01

    A high brightness X-band photoinjector, capable of multibunch operation has been developed as a collaborative effort between the UC Davis Department of Applied Science and the Synchrotron Radiation Research Center in Hsinchu, Taiwan. The high power, UHV structure is in the initial stages of high gradient testing. Simulations using SUPERFISH and PARMELA show that approximately 10 MW of drive power at 8.548 GHz will produce 4.1 MeV electron bunches. A cold test cavity model has demonstrated a ohmic Q value of 4,718 with cavity components pressed together. The closed cavity ohmic Q value simulated using SUPERFISH is 7,168. Phase stabilization measurements of a 1 kW signal from a TWTA filtered by the high Q cold test cavity are also presented.(Work supported by DoD/AFOSR MURI F49620-95-1-0253, AFOSR (ATRI) F30602-94-2-001, ARO DAAHO4-95-1-0336, LLNL/LDRD DoE W-7405-ENG-48 IUT B335885)

  9. 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.

  10. 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.

  11. 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

  12. Design of e-gun for large KrF amplifiers

    International Nuclear Information System (INIS)

    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/cm2). 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

  13. Public opinion about guns in the home

    OpenAIRE

    Kellermann, A.; Fuqua-Whitley, D.; Sampson, T.; Lindenmann, W.

    2000-01-01

    Objectives—(1) Determine the frequency of gun ownership, acquisition, and transfer; (2) assess gun storage practices; and (3) compare the views of firearm owning and non-owning adults regarding the protective value of keeping a gun in the home.

  14. Design and first cold test of BNL superconducting 112 MHz QWR for electron gun applications

    Energy Technology Data Exchange (ETDEWEB)

    Belomestnykh, S.; Ben-Zvi, I.; Boulware, C.H.; Chang, X.; Grimm, T.L.; Siegel, B.; Than, R.; Winowski, M.

    2011-03-28

    Brookhaven National Laboratory and Niowave, Inc. have designed, fabricated, and performed the first cold test of a superconducting 112 MHz quarter-wave resonator (QWR) for electron gun experiments. The first cold test of the QWR cryomodule has been completed at Niowave. The paper discusses the cryomodule design, presents the cold test results, and outline plans to upgrade the cryomodule for future experiments. A quarter-wave resonator concept of superconducting RF (SRF) electron gun was proposed at BNL for electron cooling ion/proton beams at RHIC. QWRs can be made sufficiently compact even at low RF frequencies (long wavelengths). The long wavelength allows to produce long electron bunches, thus minimizing space charge effects and enabling high bunch charge. Also, such guns should be suitable for experiments requiring high average current electron beams. A 112 MHz QWR gun was designed, fabricated, and cold-tested in collaboration between BNL and Niowave. This is the lowest frequency SRF gun ever tested successfully. In this paper we describe the gun design and fabrication, present the cold test results, and outline plans for the cryomodule upgrade for future experiments.

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

    International Nuclear Information System (INIS)

    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

  16. Weight of RCL Guns in Comparison to Conventional Guns

    Directory of Open Access Journals (Sweden)

    J. P. Sirpal

    1956-07-01

    Full Text Available A study has been made of the weight of ordnance and equipment for a given performance. The comparative weights of the RCL and the orthodox equipments have been studied and it has been found that for the same muzzle energy the weight of RCL gun is 1/4th that of orthodox gun.

  17. Development of a 500kV photoemission gun

    International Nuclear Information System (INIS)

    A high-brightness, high-current electron gun for energy recovery linac light sources, high repetition rate X-ray FEL and high power EUV FEL requires an exit beam energy of ≥ 500 keV to reduce space-charge induced emittance growth in the drift space from the gun exit to the following accelerator entrance. We demonstrated generation of a 500-keV electron beam. This demonstration was achieved by addressing two discharge problems that lead to vacuum breakdown in the dc gun. One is field emission generated from a central stem electrode. We employed a segmented insulator to protect the ceramic insulator surface from the field emission. The other is microdischarge at an anode electrode or a vacuum chamber, which is triggered by microparticle transfer or field emission from a cathode electrode. An experimental investigation revealed that a larger acceleration gap, optimized mainly to reduce the surface electric field of the anode electrode, suppresses the microdischarge events that accompany gas desorption. It was also found that nonevaporable getter pumps placed around the acceleration gap greatly help to suppress those microdischarge events. The gun has provided stable beam for commissioning of the compact ERL at KEK since April 2013. (author)

  18. Gridded gun test results for dual mode medical Linac

    International Nuclear Information System (INIS)

    As an advancement in the current low energy (6 MV) radiotherapy linac technology, SAMEER is developing a dual photon energy linac capable of giving 6 and 15 MV photons and multiple electron energies (6, 8, 10, 12, 14, 16 and 18 MeV) for electron treatment. The main feature of this development is to produce clinically acceptable quality electron beam and photon beam. The gridded gun development is a crucial part of this project because of the electron beam current requirement which ranges from milliampere to nanoampere level from photon mode to electron mode. Therefore, precise control on the beam current is key feature in linac operation. The gridded gun design specifications is given. The gun assembly was successfully carried out. The gridded gun was assembled in a test jig and baked at 100 °C. The vacuum achieved after baking was ∼10-9 mbar. The cathode activation results and DC test results were obtained. The high voltage test results in pulsed mode is discussed in this paper along with its supply. (author)

  19. Resonant optical gun.

    Science.gov (United States)

    Maslov, A V; Bakunov, M I

    2014-05-01

    We propose a concept of a structure-a resonant optical gun-to realize an efficient propulsion of dielectric microparticles by light forces. The structure is based on a waveguide in which a reversal of the electromagnetic momentum flow of the incident mode is realized by exciting a whispering gallery resonance in the microparticle. The propelling force can reach the value up to the theoretical maximum of twice the momentum flow of the initial wave. The force density oscillates along the particle periphery and has very large amplitude. PMID:24784113

  20. Numerical simulation of the sustaining discharge in radio frequency hollow cathode discharge in argon

    International Nuclear Information System (INIS)

    In this paper, a two-dimensional fluid model was developed to study the radio frequency (RF) hollow cathode discharge (HCD) in argon at 1 Torr. The evolutions of the particle density distribution and the ionization rate distribution in RF HCD at 13.56 MHz indicate that the discharge mainly occurs inside the hollow cathode. The spatio-temporal distributions of the ionization rate and the power deposition within the hollow cathode imply that sheath oscillation heating is the primary mechanism to sustain the RF HCD, whereas secondary electron emission plays a negligible role. However, as driving frequency decreases, secondary electron heating becomes a dominant mechanism to sustain the discharge in RF hollow cathode

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

    International Nuclear Information System (INIS)

    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 3x109 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.

  2. 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…

  3. Electron gun for diffraction experiments on controlled molecules

    CERN Document Server

    Müller, Nele L M; Długołecki, Karol; Küpper, Jochen

    2015-01-01

    A dc electron gun, generating picosecond pulses with up to $8\\times10^{6}$ electrons per pulse, was developed. Its applicability for future time-resolved-diffraction experiments on state- and conformer-selected laser-aligned or oriented gaseous samples was characterized. The focusing electrodes were arranged in a velocity-map imaging spectrometer configuration. This allowed to directly measure the spatial and velocity distributions of the electron pulses emitted from the cathode. In combination with electron trajectory simulations, this permitted the characterization of the electron beam in terms of coherence length and pulse duration. Electron diffraction data of a thin aluminum foil illustrated the diffraction capabilities of the electron-gun setup.

  4. 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. PMID:25646308

  5. Terahertz-driven, all-optical electron gun

    CERN Document Server

    Huang, W Ronny; Wu, Xiaojun; Cankaya, Huseyin; Calendron, Anne-Laure; Ravi, Koustuban; Zhang, Dongfang; Nanni, Emilio A; Hong, Kyung-Han; Kärtner, Franz X

    2016-01-01

    Ultrashort electron beams with narrow energy spread, high charge, and low jitter are essential for resolving phase transitions in metals, semiconductors, and molecular crystals. These semirelativistic beams, produced by phototriggered electron guns, are also injected into accelerators for x-ray light sources. The achievable resolution of these time-resolved electron diffraction or x-ray experiments has been hindered by surface field and timing jitter limitations in conventional RF guns, which thus far are 96 fs, respectively. A gun driven by optically-generated single-cycle THz pulses provides a practical solution to enable not only GV/m surface fields but also absolute timing stability, since the pulses are generated by the same laser as the phototrigger. Here, we demonstrate an all-optical THz gun yielding peak electron energies approaching 1 keV, accelerated by 300 MV/m THz fields in a novel micron-scale waveguide structure. We also achieve quasimonoenergetic, sub-keV bunches with 32 fC of charge, which ca...

  6. 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 ...

  7. 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.

  8. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source

    Science.gov (United States)

    Wells, R. P.; Ghiorso, W.; Staples, J.; Huang, T. M.; Sannibale, F.; Kramasz, T. D.

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  9. Experimental investigation of electron guns for THz microwave vacuum amplifiers

    Science.gov (United States)

    Burtsev, A. A.; Grigor'ev, Yu. A.; Navrotsky, I. A.; Rogovin, V. I.; Sakhadzhi, G. V.; Shumikhin, K. V.

    2016-05-01

    Single-sheet and multiple beam electron emitters based on thermionic minicathodes for terahertz traveling-wave tubes have been studied. Data are presented for impregnated blade thermionic cathode with dimensions 0.1 × 0.7 mm and a maximum current density of 114 A/cm2 in a pulsed mode. A variant of the five-beam electron gun with 0.25-mm-diameter cylindrical minicathodes in cells of a control grid is proposed that provides a current density of 85.5 A/cm2 at a grid potential of 900-1000 V.

  10. 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...

  11. RK-TBA prototype RF source

    International Nuclear Information System (INIS)

    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

  12. Calculating effective gun control policies

    CERN Document Server

    Wodarz, Dominik

    2013-01-01

    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 population dynamic 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: either a ban of private firearms possession, or a policy allowing the general population to carry guns. In particular, the outcome depends on the fraction of offenders that illegally possess a gun, on the degree of protection provided by gun ownership, and on the fraction of the population who take up their right to own a gun and carry it with them when attacked, parameters that can be estimated from statistical data. With the measured parameters, the model suggests that if the gun law is enforced at a level similar to that in the United Kingdom, g...

  13. Guns as a Symbol of American Individualism

    Institute of Scientific and Technical Information of China (English)

    许丹

    2011-01-01

    Due to continuous gun violence, Americans' crazy love for guns has always been attacked home and abroad. Americans' passion for guns derives from individualism through the development of American history. They consider guns as a means to guarantee independence and freedom, and therefore as a symbol of American individualism.

  14. 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 be

  15. Long-term behavior of the electron gun emission property at LEBRA linac

    International Nuclear Information System (INIS)

    The electron beam from the 125 MeV electron linac at the Laboratory for Electron Beam Research and Application in Nihon University has been used for generation of the infrared Free Electron Laser (FEL) and Parametric X-rays (PXR). The electron beam can be extracted from the electron gun in three different modes, the conventional full-bunch mode, the burst mode, and the superimposed mode of the full-bunch and the burst modes. Since the replacement of the gun cathode by a new one in 2012, a significant decay in the extracted beam current during the macropulse had been found in the burst and the superimposed mode beams. Gradually the decay in the beam current has been recovered by continuous cathode heating over more than 1 year. The vacuum leak that occurred at around the flange of the cathode assembly in the early stage of the cathode activation process is considered as the dominant cause of the behavior of the gun. (author)

  16. An in-situ photocathode loading system for the SLC Polarized Electron Gun

    International Nuclear Information System (INIS)

    An ultra-high vacuum loadlock system capable of operating at high voltage has been added to the SLC Polarized Electron Gun. The unit incorporates facilities for heat cleaning, activating and measuring the quantum efficiency of photocathodes. A tray of up to four photocathodes can be exchanged without bringing the activation unit or gun up to atmosphere. Low voltage quantum efficiencies of 20% have been obtained for bulk GaAs at 633 nm and 6% for a 0.3 micron GaAs layer at 755 nm. Results for other cathodes as well as operational characteristics are discussed

  17. Electron gun with off-axis beam injection for a race-track microtron

    International Nuclear Information System (INIS)

    A miniature 12 MeV race-track microtron for medical applications is under construction at the Technical University of Catalonia in collaboration with several Spanish centers and companies and the Skobeltsyn Institute of Nuclear Physics of the Moscow State University. As a source of electrons a compact 3D on-axis electron gun with an off-axis cathode has been designed to allow a direct and efficient injection into the accelerating structure. Its prototype has been built and successfully tested. Results of the electron gun design simulations and of the prototype performance are herein described.

  18. A high-duty-cycle long-pulse electron gun for electron accelerators

    Science.gov (United States)

    Ebrahim, N. A.; Thrasher, M. H.

    1990-11-01

    We describe the design and operation of a long-pulse (200-300 μs), high-duty-cycle (5%-6%), 8-mm-diam dispenser cathode, electrically isolated, modulating Wehnelt electron gun for applications in a high-average-power electron linear accelerator. The electron optics design was optimized with computer modeling of the electron trajectories and equipotentials. The gun performance was established in a series of experimental measurements in a test stand. Excellent pulse-to-pulse emission current reproducibility and electron-beam pulse profile stability were obtained.

  19. Scanning beam switch experiment for intense rf power generation

    Science.gov (United States)

    Humphries, Stanley, Jr.; Babcock, Steven R.; Wilson, J. M.; Adler, Richard J.

    1991-04-01

    1407_57The SBS_1 experiment at Sandia National Laboratories is designed to demonstrate the feasibility of the Scanning Beam Switch for high-power rf generation. The primary application is to pulsed rf linacs and high-frequency induction accelerators. It is expected that the apparatus will generate rf output power exceeding 100 MW at 50 MHz over a 5 microsecond(s) pulse. The device can operate as an oscillator or high gain amplifier. To achieve the capability for long-macropulse and high-duty-cycle operation, SBS_1 uses a large dispenser cathode and vacuum triode input driver.

  20. Status of superconducting RF test facility (STF)

    International Nuclear Information System (INIS)

    The superconducting RF test facility (STF) in KEK is the R and D facility for the International Linear Collider (ILC) cavities and cryomodule. The surface treatment and field test of fabricated 9-cell superconducting cavities are performed for the cryomodule installation. As an international project, S1-Global cryomodule test was successfully completed for the various studies on different type of cavity system. The construction of the Quantum-Beam experiment accelerator, as part of STF phase-2 development, has started in 2011, after the S1-Global cryomodule dis-installation from the tunnel. The photocathode RF gun and the capture cryomodule are constructed, installed and commissioned. All of the STF development done in 2011-2012 is summarized in this paper. (author)

  1. Status of superconducting RF test facility (STF)

    International Nuclear Information System (INIS)

    The superconducting RF test facility (STF) in KEK is the facility to promote R and D of the International Linear Collider (ILC) cavities and cryomodule. The STF accelerator to promote the Quantum beam project was installed, commissioned and operated in 2011-2012. It consists of the L-band photocathode RF-gun, two superconducting cavities, and the Compton chamber, which was combined and utilized 4-mirror laser accumulator. The X-ray generation experiment in the accelerator was successfully performed. Now, the accelerator is under installation of the 12m-cryomodule and another 6m-cryomodule. All of the STF development done in 2012-2013 is summarized in this paper. (author)

  2. Child Access Prevention Laws and Nonfatal Gun

    OpenAIRE

    Jeffrey DeSimone; Sara Markowitz

    2013-01-01

    Many states have passed child access prevention (CAP) laws, which hold the gun owner responsible if a child gains access to a gun that is not securely stored. Previous research on CAP laws has focused exclusively on gun-related deaths even though most gun injuries are not fatal. We use annual hospital discharge data to investigate whether CAP laws are associated with decreased nonfatal gun injuries. Results from Poisson regressions that control for various hospital, county, and state characte...

  3. 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...

  4. 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.

  5. 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.

  6. TARN rf stacking system

    International Nuclear Information System (INIS)

    Repetitive rf stacking system for the TARN was developed. The developed system consists of ferrite loaded rf cavity, rf power amplifier, ferrite bias power supply and low level rf electronics. Ferrite material and rf signal source were studied to obtain a high-duty and precise moving rf bucket. Phase lock technic worked at a low intensity beam was also studied. Repetition rate of 50 Hz and final stacking number of 50 were attained at the injection beam energy of 7 MeV/u. (author)

  7. Recycler barrier RF buckets

    CERN Document Server

    Bhat, C M

    2012-01-01

    The Recycler Ring at Fermilab uses a barrier rf system for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf systems, 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.

  8. 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.

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

    OpenAIRE

    Brian Knight

    2011-01-01

    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...

  10. Development of field-emission electron gun from carbon nanotubes (2)

    International Nuclear Information System (INIS)

    We have been developing a high brightness electron gun utilizing carbon nanotube (CNT) cathode since 2001. Recently we succeeded to achieve a realistic-size cold cathode which could stand comparison with current densities of dispenser cathodes conventionally used in accelerators all over the world. The anode current was obtained to 0.48 A from the CNT-cathode of 2.6 mm diameter, which current density reduced from the anode current was about 9.1 A/cm2 under a condition of 128 kV-DC acceleration voltage in pulse operations of 50 pps using about 8 ns pulses. The emission current was very stable in the long-term-period operation for about 3 weeks under about 10-6 Pa vacuum pressure. (author)

  11. 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...

  12. Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

    International Nuclear Information System (INIS)

    Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions’ charge states, and therefore, the ions’ energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

  13. Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

    Science.gov (United States)

    Pikin, A.; Beebe, E. N.; Raparia, D.

    2013-03-01

    Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

  14. Effects of RF plasma processing on the impedance and electron emission characteristics of a MV beam diode

    International Nuclear Information System (INIS)

    Experiments have proven that both the surface contaminants and microstructure topography on the cathode of an electron beam diode influence impedance collapse and electron emission current. Experiments have characterized effective RF plasma processing protocols for high voltage A-K gaps using argon and argon/oxygen gas mixtures. RF processing time, feed gas pressure, and RF power were adjusted. Time resolved optical emission spectroscopy measured contaminant (hydrogen) and bulk cathode (aluminum) plasma emission versus transported axial electron beam current. Experiments utilize the Michigan Electron Long Beam Accelerator (MELBA) at parameters: V = -0.7 to minus1.0 MV, I(diode) + 3--30 kA, and pulse length = 0.4 to 1.0 microseconds. Microscopic and macroscopic E-fields on the cathode were varied to characterize the scaling of breakdown conditions for contaminants versus the bulk material of the cathode after plasma processing. Electron emission was suppressed for an aluminum cathode in a high voltage A-K gap after RF plasma processing. Experiments using a two-state low power (100W) argon/oxygen RF discharge followed by a higher power (200W) pure argon RF discharge yielded an increase in turn-on voltage required for axial current emission from 662 ± 174 kV to 981 ± 97 kV. After two-stage RF plasma processing axial current emission turn-on time was increased from 100 ± 22 nanoseconds to 175 ± 42 nanoseconds. Aluminum optical emission was delayed > 150 nanoseconds after the overshoot in voltage after two-stage RF plasma processing. Removal of hydrogen contamination on the cathode surface was observed by optical spectroscopy during the MELBA pulse. Axial and diode current were reduced 40--100% after RF plasma processing. SEM analysis suggests the aluminum cathode surface is being modified by the RF plasma discharge

  15. 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. PMID:24783322

  16. 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.

  17. Analysis and design of double-anode magnetron injection gun for 170 GHz gyrotron

    International Nuclear Information System (INIS)

    Based on adiabatic compression theory and electro-optical theory, a double-anode magnetron injection gun for 170 GHz gyrotron was designed. By theoretical analysis and calculations, using simulation software to simulate and optimize the electron gun, and got the result that the velocity ratio of electron beam was 1.31, the transverse velocity spread was 3.5% and the axial velocity spread was 7.1%, the beam current was 51 A. The effects of the cathode magnetic field, the control Jantage and the second anode Jantage on the properties of electron beam were discussed and found that electron beam were very sensitive with these factors. When cathode magnetic field increased, the velocity ratio of electron beam decreased, the axial velocity spread increased first and then decreased, the transverse velocity spread decreased first and then increased. The increase of the first anode Jantage could improve the velocity ratio and velocity spread of electron beam. The closer the anode angle and cathode angle, the smaller axial velocity spread. The transverse velocity spread became smaller while the anode angle changed toward the direction of reducing the distance between anode could cathode. When the two anode Jantage did not change, the increase of the distance between cathode and anode could minish the velocity spread of electron beam but the velocity ratio decreased at the same time. (authors)

  18. Lake Wobegon’s Guns: Overestimating Our Gun-Related Competences

    Directory of Open Access Journals (Sweden)

    Emily Stark

    2016-02-01

    Full Text Available The Lake Wobegon Effect is a general tendency for people to overestimate their own abilities. In this study, the authors conducted a large, nationally-representative survey of U.S. citizens to test whether Americans overestimate their own gun-relevant personality traits, gun safety knowledge, and ability to use a gun in an emergency. The authors also tested how gun control attitudes, political identification, gender, and gun experience affect self-perceptions. Consistent with prior research on the Lake Wobegon Effect, participants overestimated their gun-related competencies. Conservatives, males, and pro-gun advocates self-enhanced somewhat more than their counterparts but this effect was primarily due to increased gun experience among these participants. These findings are important to policymakers in the area of gun use, because overconfidence in one’s gun-related abilities may lead to a reduced perceived need for gun training.

  19. Development of a dual-pulse RF driver for an S-band (= 2856 MHz) RF electron linear accelerator

    Science.gov (United States)

    Cha, Sungsu; Kim, Yujong; Lee, Byeong-No; Lee, Byung Cheol; Cha, Hyungki; Ha, Jang Ho; Park, Hyung Dal; Lee, Seung Hyun; Kim, Hui Su; Buaphad, Pikad

    2016-04-01

    The radiation equipment research division of Korea Atomic Energy Research Institute has developed a Container Inspection System (CIS) using a Radio Frequency (RF) electron linear accelerator for port security. The primary purpose of the CIS is to detect nuclear materials and explosives, as well country-specific prohibited substances, e.g., smuggled. The CIS consists of a 9/6 MeV dualenergy electron linear accelerator for distinguishing between organic and inorganic materials. The accelerator consists of an electron gun, an RF accelerating structure, an RF driver, a modulator, electromagnets, a cooling system, a X-ray generating target, X-ray collimator, a detector, and a container moving system. The RF driver is an important part of the configuration because it is the RF power source: it supplies the RF power to the accelerating structure. A unique aspect of the RF driver is that it generates dual RF power to generate dual energy (9/6 MeV). The advantage of this RF driver is that it can allow the pulse width to vary and can be used to obtain a wide range of energy output, and pulse repetition rates up to 300 Hz. For this reason, 140 W (5 MW - 9 MeV) and 37 W (3.4 MW - 6 MeV) power outputs are available independently. A high power test for 20 minutes demonstrate that stable dual output powers can be generated. Moreover, the dual power can be applied to the accelerator which has stable accelerator operation. In this paper, the design, fabrication and high power test of the RF driver for the RF electron linear accelerator (linac) are presented.

  20. [Suicide with home-made gun].

    Science.gov (United States)

    Safr, M; Hejna, P; Zátopková, L

    2009-04-01

    Three cases of suicide by single bullet injury to head by home-made guns with immediate incapacitation are reported in following article. Zip gun (home-made gun) is a improvised firearm, usually a handgun. Home-made guns are almost always single-shot, as the improvised construction sometimes makes them weak enough to be destroyed by the act of firing. Zip guns are mostly smoothbore. Zip gun injuries, although unique today, represent a special category of missile injury with atypical low velocity terminal ballistics. PMID:19534397

  1. The Social Costs of Gun Ownership

    OpenAIRE

    Phillip J. Cook; Jens Ludwig

    2004-01-01

    This paper provides new estimates of the effect of household gun prevalence on homicide rates, and infers the marginal external cost of handgun ownership. The estimates utilize a superior proxy for gun prevalence, the percentage of suicides committed with a gun, which we validate. Using county- and state-level panels for 20 years, we estimate the elasticity of homicide with respect to gun prevalence as between +.1 and +.3. All of the effect of gun prevalence is on gun homicide rates. Under ce...

  2. Fast deposition of diamond-like carbon films by radio frequency hollow cathode method

    International Nuclear Information System (INIS)

    Diamond-like carbon (DLC) thin films were deposited on p-type Si (100) substrates by RF hollow cathode method under different RF power and pressure, using ethane as the precursor gas. The deposition rate of 45 nm/min was achieved, almost 4 times higher than by conventional radio frequency plasma enhanced chemical vapor deposition. The mechanism of fast DLC films deposition is attributed to high plasma density in RF hollow cathode method, discussed in this paper. Scanning electron microscopy and Raman spectroscopy were used to investigate the microstructure of DLC films. The film hardness and Young's modulus were measured by nanoindentation. - Highlights: • Diamond-like carbon thin films were deposited by RF hollow cathode method. • The deposition rate of 45 nm/min was achieved. • A higher plasma density results in a higher deposition rate

  3. Development of compact gas treatment system using secondary emission electron gun

    CERN Document Server

    Watanabe, M; Okino, A; Ko, K C; Hotta, E; Watanabe, Masato; Wang, Yu; Okino, Akitoshi; Ko, Kwang-Cheol; Hotta, Eiki

    2004-01-01

    It is well known that the non-thermal plasma processes using electrical discharge or electron beam are effective for the environmental pollutant removal. Especially, the electron beam can efficiently remove pollutant, because a lot of radicals which are useful to remove pollutant can be easily produced by high-energy electrons. We have developed a compact 100kV secondary emission electron gun to apply NOX removal. The device offers several inherent advantages such as compact in size, wide and uniform electron beam. Besides, the device offers good capability in high repetition rate pulsed operation with easy control compared with glow discharge or field emission control cathode guns. In present study, the NOX removal characteristics have been studied under the increased gun voltage, varied pulsed electron beam parameters such as current density and pulse width as well as gas flow rate. The experimental results indicate a better NOX removal efficiency comparing to other high-energy electron beam and electrical ...

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

    International Nuclear Information System (INIS)

    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)

  5. Polarized gun and ERL R and D for eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi,I.

    2009-05-27

    At Jefferson Laboratory charge density and charge lifetime during electron beam delivery are over 2 x 10{sup 5} C/cm{sup 2} and 200 C, respectively. A 200 C charge lifetime at 2 mA corresponds to 10{sup 5} seconds. In a more recent result, charge lifetimes of about an order of magnitude larger were achieved by a load-lock gun with a larger cathode area.

  6. Development of Grid Control Electron Gun for Multi-energy Irradiation Accelerator

    Institute of Scientific and Technical Information of China (English)

    HAN; Guang-wen; ZHU; Zhi-bin; WANG; Shu-xian

    2012-01-01

    <正>In the project of multi-energy electron irradiation accelerator, It is necessary to adjust the electron beam pulse inject to the accelerating tube. Under the same conditions of the injection energy, the grid controlled electron gun was used in the accelerator. Using cathode-grid assembly, after the simulation of electron optics program design, we manufactured focus electrode, the anode, and built an experiment

  7. Design of a LaB6 gun using EGN2 and INTMAG

    International Nuclear Information System (INIS)

    In order to launch a high-density electron beam to be focused in the 5 T superconducting solenoid of the Frankfurt EBIS an electron gun has been designed, with a 0,5 mm diameter LaB6 cathode in a 70 mm diameter electrode geometry. The emitting surface is placed in the axial fringing field of the solenoid, modified by an axial shielding disk and a bucking coil, to provide either immersed flow or Brillouin flow conditions for the focused beam. Since the cathode diameter is small as compared to the electrodes, a new feature of EGN2 had to be used in order to have a sufficient number of meshes along the emitting surface. By starting a field line in the large geometry, a curved Neumann boundary is found for a subdivided part of the gun, which represents the influence of the larger part. EGN2 writes the coordinates of this field line on a file, which can be used by POLYGON (a boundary setup program for EGN2) to define a curved Neumann boundary. By this procedure, it becomes possible to get a reliable simulation of the emission properties of a small cathode in large gun electrodes. The magnetostatic field calculations have been performed with INTMAG which is a new program of the boundary element method type. Due to the integration calculus, the results do not need smoothing or 'Maxwellisation' for the use in EGN2, where the off-axis fields are evaluated by radial expansion. INTMAG provides an output file, which is suitably formatted to be read in by EGN2. The gun design is based on space-charge-limited emission, but no Pierce-type electrode has been provided in the vicinity of the cathode; instead a Wehnelt electrode on negative bias with respect to the cathode is used to create the correct Pierce-type equipotential in free space, ending on the cathode edge with the correct angle. This gives an additional adjustment tool, if the axial position of the gun is not perfect and it relaxes the radial tolerance requirements considerably. (orig./HSI)

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

    International Nuclear Information System (INIS)

    An important aspect of the development of multi-cell RF accelerating structures is tuning the resonant frequency f of the operating mode, field balance eb, 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, eb, 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

  9. Design of magnetron injection gun for 94 GHz gyro-amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, K.; Danly, B.; Levush, B.; Blank, M. [Naval Research Lab., Washington, DC (United States); Liu, C.; Antonsen, T. [Univ. of Maryland, College Park, MD (United States)

    1996-12-31

    The Naval Research Laboratory has recently initiated design and development effort to develop a high average power GHz gyroklystron. The amplifier will operate in the TE{sub 01} mode the fundamental cyclotron harmonic. Because of the critical dependence of gyro-amplifier efficiency on the electron beam quality, a key element in this effort is the gun design. The overall goal of the gun design work is to account for various contribution factors to beam velocity spread and to minimize the beam sensitivity to their influence. In addition to the beam spread resulting from the usual beam optics, these factors include cathode surface roughness and misalignments. The magnetron injection gun (MIG) point design employs double-anode geometry and a cathode angle of 45{degree} to produce a 5--65 kV gyrating beam with a velocity ratio ({alpha}) of 1.4. The EGUN simulated beam optics perpendicular velocity spread ({delta}v{sub p}/v{sub p}) 1.9%. Further details on the gun geometry and results from the given design sensitivity study will be presented and discussed at the conference.

  10. Development of coaxial rotating-plasma gun

    International Nuclear Information System (INIS)

    A rotating-plasma gun has been devised to produce plasma streams with higher rotational velocities. The working mechanism of the gun and the results of a preliminary experiment have been described. (author)

  11. States with More Gun Owners Have More Gun-Related Suicides: Study

    Science.gov (United States)

    ... gov/news/fullstory_158931.html States With More Gun Owners Have More Gun-Related Suicides: Study But only association was found, ... HealthDay News) -- In states where there are more gun owners, there are also more gun-related suicides, ...

  12. States with More Gun Owners Have More Gun-Related Suicides: Study

    Science.gov (United States)

    ... medlineplus/news/fullstory_158931.html States With More Gun Owners Have More Gun-Related Suicides: Study But only association was found, ... HealthDay News) -- In states where there are more gun owners, there are also more gun-related suicides, ...

  13. Plasma focusing in coaxial gun

    International Nuclear Information System (INIS)

    A capacitor bank has been discharged between two coaxial electrodes of 6.6 cm outer diameter, 3.2 cm inner diameter and length of 31.5 cm. filled with hydrogen gas at pressure of 310 μHg. Results show that, the axial and radial plasma current reach a maximum value at a position adjacent to the gun muzzle, at which the plasma focus occurs. The measurement of the electron temperature and density and azimuthal electric field along the axis of the expansion chamber, gives a maximum value at z∼18 cm from the gun muzzle, while the axial plasma current and velocity has a minimum value at that position. These results indicate that a second point of a plasma focus has been formed at z∼18 cm from the gun muzzle, along the axis of the expansion chamber

  14. Automatic targeting of plasma spray gun

    International Nuclear Information System (INIS)

    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

  15. Automatic targeting of plasma spray gun

    Science.gov (United States)

    Abbatiello, Leonard A.; Neal, Richard E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is provided. 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.

  16. A Fully-Sealed Carbon-Nanotube Cold-Cathode Terahertz Gyrotron.

    Science.gov (United States)

    Yuan, Xuesong; Zhu, Weiwei; Zhang, Yu; Xu, Ningsheng; Yan, Yang; Wu, Jianqiang; Shen, Yan; Chen, Jun; She, Juncong; Deng, Shaozhi

    2016-01-01

    Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is realized, typically with output power of 500 mW. To achieve this, we have studied mechanisms responsible for CNTs growth on curved shape metal surface, field emission from the sidewall of a CNT, and crystallized interface junction between CNT and substrate material. We have obtained uniform growth of CNTs on and direct growth from cone-cylinder stainless-steel electrode surface, and field emission from both tips and sidewalls of CNTs. It is essential for the success of a CNT terahertz gyrotron to have such high quality, high emitting performance CNTs. Also, we have developed a magnetic injection electron gun using CNT cold-cathode to exploit the advantages of such a conventional gun design, so that a large area emitting surface is utilized to deliver large current for electron beam. The results indicate that higher output power and higher radiation frequency terahertz gyrotron may be made using CNT cold-cathode electron gun. PMID:27609247

  17. Liquid Propellants for Advanced Gun Ammunitions

    Directory of Open Access Journals (Sweden)

    K. P. Rao

    1987-01-01

    Full Text Available With constant improvements, the conventional solid propellants for guns have almost reached their limit in performance. Liquid gun propellants are promising new comers capable of surpassing these performance limits and have numerous advantages over solid propellants. A method has been worked out to predict the internal ballistics of a liquid propellant gun and illustrated in a typical application.

  18. Liquid Propellants for Advanced Gun Ammunitions

    OpenAIRE

    K. P. Rao; A. S. Bartakke; R.G.K. Nair

    1987-01-01

    With constant improvements, the conventional solid propellants for guns have almost reached their limit in performance. Liquid gun propellants are promising new comers capable of surpassing these performance limits and have numerous advantages over solid propellants. A method has been worked out to predict the internal ballistics of a liquid propellant gun and illustrated in a typical application.

  19. The supply and demand for guns to juveniles: Oakland’s gun tracing project

    OpenAIRE

    Calhoun, Deane; Dodge, Andrea Craig; Journel, Coraline S.; Zahnd, Elaine

    2005-01-01

    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...

  20. Using Multispectral Imaging to Measure Temperature Profiles and Emissivity of Large Thermionic Dispenser, Cathodes

    International Nuclear Information System (INIS)

    Thermionic dispenser cathodes are widely used in modern high-power microwave tubes. Use of these cathodes has led to significant improvement in performance. In recent years these cathodes have been used in electron linear accelerators (LINACs), particularly in induction LINACs, such as the Experimental Test Accelerator at Lawrence Livermore National Laboratory and the Relativistic Test Accelerator at Lawrence Berkeley National Laboratory. For induction LINACs, the thermionic dispenser cathode provides greater reproducibility, longer pulse lengths, and lower emittance beams than does a field emission cathode. Los Alamos National Laboratory is fabricating a dual-axis X-ray radiography machine called dual-axis radiograph hydrodynamic test (DARHT). The second axis of DARHT consists of a 2-kA, 20-MeV induction LINAC that uses a 3.2-MeV electron gun with a tungsten thermionic-dispenser cathode. Typically the DARHT cathode current density is 10 A/cm2 at 1050 C. Under these conditions current density is space-charge limited, which is desirable since current density is independent of temperature. At lower temperature (the temperature-limited regime) there are variations in the local current density due to a nonuniform temperature profile. To obtain the desired uniform current density associated with space-charge limited operation, the coolest area on the cathode must be at a sufficiently high temperature so that the emission is space-charge limited. Consequently, the rest of the cathode is emitting at the same space-charge-limited current density but is at a higher temperature than necessary. Because cathode lifetime is such a strong function of cathode temperature, there is a severe penalty for nonuniformity in the cathode temperature. For example, a temperature increase of 50 C means cathode lifetime will decrease by a factor of at least four. Therefore, we are motivated to measure the temperature profiles of our large-area cathodes

  1. 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...

  2. Emission characteristics of dispenser cathodes with a fine-grained tungsten top layer

    Science.gov (United States)

    Kimura, S.; Higuchi, T.; Ouchi, Y.; Uda, E.; Nakamura, O.; Sudo, T.; Koyama, K.

    1997-02-01

    In order to improve the emission stability of the Ir-coated dispenser cathode under ion bombardment, a fine-grained tungsten top layer was applied on the substrate porous tungsten plug before Ir coating. The emission characteristics were studied after being assembled in a CRT gun. Cathode current was measured under pulse operation in a range of 0.1-9% duty. Remarkable anti-ion bombardment characteristics were observed over the range of 1-6% duty. The improved cathode showed 1.5 times higher emission current than that of a conventional Ir-coated dispenser cathode at 4% duty. AES analysis showed that the recovering rates of surface Ba and O atoms after ion bombardment were 2.5 times higher. From these results it is confirmed that the Ir coated cathode with a fine-grained tungsten top layer is provided with a good tolerance against the ion bombardment.

  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. The ELETTRA Gun Trigger module

    International Nuclear Information System (INIS)

    The ELETTRA injector is a full energy Linac. The Linac and the pulsed magnets need to be synchronized with the beam in the storage ring in order to fill it with the proper bunch pattern. Most of the triggers for the timing system are generated by a module which is named Gun Trigger module. The gun is triggered in synchronism with a reference bucket of the storage ring. It can be programmed with a delay between 2 and 864 ns, a range which covers one revolution period of the storage ring, so any arbitrary bucket of the ring can be filled. The module generates also the gun trigger for working in FEL mode, which needs a repetition from 30 to 50 ns in a 10 μs window. The jitter of all these triggers is less than 50 ps. The Gun Trigger module is developed in VMEbus standard, using TTL and ECL technology. It is remotely programmable through the ELETTRA control system. The general architecture of the ELETTRA timing system is also described in the paper

  5. Current controller for electron gun

    International Nuclear Information System (INIS)

    A beam-current controller for a triode electron gun is described that permits the voltage on the control electrode to be varied within 0-2.5 kV with 60-kV isolation of the output part of the circuit from the low-potential control-signal source. The carrier frequency for control-signal conversion is 32 khz

  6. Developments in electron gun simulation

    Energy Technology Data Exchange (ETDEWEB)

    Herrmannsfeldt, W.B.

    1994-05-01

    This paper will discuss the developments in the electron gun simulation programs that are based on EGUN and its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications on EGN2 of this evolution will be discussed. Some examples and a review of the capabilities of the EGUN family will be described.

  7. Developments in electron gun simulation

    International Nuclear Information System (INIS)

    This paper will discuss the developments in the electron gun simulation programs that are based on EGUN and its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications on EGN2 of this evolution will be discussed. Some examples and a review of the capabilities of the EGUN family will be described

  8. Electric rail gun application to space propulsion

    International Nuclear Information System (INIS)

    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

  9. Revisiting Pneumatic Nail Gun Trigger Recommendations

    OpenAIRE

    Albers, James; Lowe, Brian; Lipscomb, Hester; Hudock, Stephen; Dement, John; Evanoff, Bradley; Fullen, Mark; Gillen, Matt; Kaskutas, Vicki; Nolan, James; Patterson, Dennis; Platner, James; Pompeii, Lisa; Schoenfisch, Ashley

    2015-01-01

    Use of a pneumatic nail gun with a sequential actuation trigger (SAT) significantly diminishes the risk for acute traumatic injury compared to use of a contact actuation trigger (CAT) nail gun. A theoretically-based increased risk of work-related musculoskeletal disorders from use of a SAT nail gun, relative to CAT, appears unlikely and remains unproven. Based on current knowledge, the use of CAT nail guns cannot be justified as a safe alternative to SAT nail guns. This letter provides a pers...

  10. 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)

  11. RF gymnastics in synchrotrons

    OpenAIRE

    Garoby, R.

    2011-01-01

    The RF systems installed in synchrotrons can be used to change the longitudinal beam characteristics. 'RF gymnastics' designates manipulations of the RF parameters aimed at providing such non-trivial changes. Some keep the number of bunches constant while changing bunch length, energy spread, emittance, or distance between bunches. Others are used to change the number of bunches. After recalling the basics of longitudinal beam dynamics in a hadron synchrotron, this paper deals with the most c...

  12. R&D ERL: High power RF systems

    Energy Technology Data Exchange (ETDEWEB)

    Zaltsman, A.

    2010-01-15

    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 2.5 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.

  13. 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.

  14. Effect of nitrogen flow rate on properties of CrN films Prepared by HCD-gun

    OpenAIRE

    A.J. Novinrooz; H. Seyedi

    2006-01-01

    Purpose: The effect of reactant nitrogen gas flow rate on the tribological properties of CrN thin films was studied.Design/methodology/approach: Hollow Cathode Discharge gun (HCD-gun) was employed for the coating of CrN films on the glass and SS-316 sub strum. The reactant nitrogen with different flow was fed in to the vacuum chamber of 3x10-3 Pa pressure to form Cr N composite under experimental condition.Findings: The crystalline phase and micro structural studies of the specimens were carr...

  15. Autonomous portable pulsed-periodical generator of high-power radiofrequency-pulses based on gas discharge with hollow cathode

    Science.gov (United States)

    Bulychev, Sergey V.; Dubinov, Alexander E.; L'vov, Igor L.; Popolev, Vyacheslav L.; Sadovoy, Sergey A.; Sadchikov, Eugeny A.; Selemir, Victor D.; Valiulina, Valeria K.; Vyalykh, Dmitry V.; Zhdanov, Victor S.

    2016-05-01

    Portable autonomous generator of high-power RF-pulses based on the gas discharge with hollow cathode has been designed, fabricated, and tested. Input and output characteristics are the following: discharge current amplitude is 800 A, duration of generated RF-pulses is 350 ns, carrier frequency is ˜90 MHz, power in RF-pulse is 0.5 MW, pulse repetition rate is 0.5 kHz, and device efficiency is ˜25%.

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

    International Nuclear Information System (INIS)

    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

  17. Effects of a Gun Dealer's Change in Sales Practices on the Supply of Guns to Criminals

    OpenAIRE

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

    2006-01-01

    Licensed gun dealers are a major conduit for gun trafficking. Prior to May 1999, a single gun store sold more than half of the guns recovered from criminals in Milwaukee, WI, shortly following retail sale. On May 10, 1999, the store stopped selling small, inexpensive handguns popular with criminals, often called “Saturday night specials.” The purpose of this study was to estimate the effect of this gun store's changed sales practices on criminals' acquisition of new guns. We used an interrupt...

  18. The Effect of Gun Shows on Gun-Related Deaths: Evidence from California and Texas

    OpenAIRE

    Mark Duggan; Randi Hjalmarsson; Brian A. Jacob

    2008-01-01

    Thousands of gun shows take place in the U.S. each year. Gun control advocates argue that because sales at gun shows are much less regulated than other sales, such shows make it easier for potential criminals to obtain a gun. Similarly, one might be concerned that gun shows would exacerbate suicide rates by providing individuals considering suicide with a more lethal means of ending their lives. On the other hand, proponents argue that gun shows are innocuous since potential criminals can acq...

  19. Rf power sources

    International Nuclear Information System (INIS)

    In this paper, the author reports on RF power sources for accelerator applications. The approach will be with particular customers in mind. These customers are high energy physicists who use accelerators as experimental tools in the study of the nucleus of the atom, and synchrotron light sources derived from electron or positron storage rings. The author pays close attention to electron- positron linear accelerators since the RF sources have always defined what is possible to achieve with these accelerators. Circular machines, cyclotrons, synchrotrons, etc. have usually not been limited by the RF power available and the machine builders have usually had their RF power source requirements met off the shelf. The main challenge for the RF scientist has been then in the areas of controls. An interesting example of this is in the Conceptual Design Report of the Superconducting Super Collider (SSC) where the RF system is described in six pages of text in a 700-page report. Also, the cost of that RF system is about one-third of a percent of the project's total cost. The RF system is well within the state of the art and no new power sources need to be developed. All the intellectual effort of the system designer would be devoted to the feedback systems necessary to stabilize beams during storage and acceleration, with the main engineering challenges (and costs) being in the superconducting magnet lattice

  20. Optimization of beam parameters of electron gun for 2.5 MeV/100 kW high power industrial accelerator

    International Nuclear Information System (INIS)

    A 2.5 MeV/100 kW transformer type industrial accelerator is being developed at RRCAT. A Pierce type electron gun consisting of 10 mm diameter LaB6 disc (indirectly heated) is used as a source of electron beam. The cathode assembly is put on the top of the accelerating structure, which consists of many electrostatic lenses of which the first lens acts as anode of the gun. The quality of the beam injected into the accelerating structure depends on the anode voltage, shape and size of anode and its distance from the cathode. The anode is subjected to variable voltage during the operation of accelerator from energy 1 MeV to 2.5 MeV, which results in variable emittance at the exit of the electron gun. The electron beam from the gun should provide parallel or slightly convergent beam with long focal length and the emittance of the beam at the exit of electron gun should match the beam acceptance limit of the accelerating structure. The EGUN code is used to optimize the shape and size of the anode, its distance from the cathode to achieve above objectives. Our study suggests that the desired beam parameters at the exit of the anode can be obtained by reducing the aperture size of the anode and by applying suitable voltage gradient to the anode. (author)