Journal articles: 'Electron beam operation'

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Iiyoshi, Ryo, Susumu Maruse, and Hideo Takematsu. "Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 198–99. http://dx.doi.org/10.1017/s0424820100179749.

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Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

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Tono, Kensuke, Toru Hara, Makina Yabashi, and Hitoshi Tanaka. "Multiple-beamline operation of SACLA." Journal of Synchrotron Radiation 26, no. 2 (February 22, 2019): 595–602. http://dx.doi.org/10.1107/s1600577519001607.

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The SPring-8 Ångstrom Compact free-electron LAser (SACLA) began parallel operation of three beamlines (BL1–3) in autumn 2017 to increase the user beam time of the X-ray free-electron laser. The success of the multiple-beamline operation is based on two technological achievements: (i) the fast switching operation of the SACLA main linear accelerator, which provides BL2 and BL3 with pulse-by-pulse electron beams, and (ii) the relocation and upgrade of the SPring-8 Compact SASE Source for BL1, for the generation of a soft X-ray free-electron laser. Moreover, the photon beamlines and experimental stations were upgraded to facilitate concurrent user experiments at the three beamlines and accommodate more advanced experiments.

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Pagonakis, Ioannis, Stefano Alberti, Konstantinos Avramidis, Francois Legrand, Gerd Gantenbein, Jérémy Genoud, Jean-Philippe Hogge, et al. "Overview on recent progress in magnetron injection gun theory and design for high power gyrotrons." EPJ Web of Conferences 203 (2019): 04011. http://dx.doi.org/10.1051/epjconf/201920304011.

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The magnetron injection gun (MIG) is one of the most critical subcomponents in gyrotrons. The electron beam, which has the primary role on the gyrotron operation, is generated and configured at this part of the tube. The electron beam properties determine the excitation mode in the cavity, the power of the generated microwaves and the gyrotron efficiency. The operation of MIGs could be influenced by several factors such as trapped electrons, manufacturing tolerances, roughness of the emitter ring, emitter temperature inhomogeneity, electron beam neutralization effect, etc. The influence of many of these factors on the electron beam quality has been systematically investigated during the last years. Several novelties have been proposed in order to limit the influence of these factors on the gyrotron operation. In particular, new design criteria have been proposed for the suppression of electron trapping mechanisms, a new type of the emitter ring has been proposed to minimize the influence of the manufacturing tolerances and edge effects on the beam quality, alternative MIG design approaches have been proposed, etc. An overview of all these works will be presented here.

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ARZHANNIKOV, A. V., V. T. ASTRELIN, V. S. KOIDAN, and S. L. SINITSKY. "Resonant principle for operation of energy recuperator for a magnetized electron beam: A numerical simulation." Laser and Particle Beams 20, no. 2 (April 2002): 359–64. http://dx.doi.org/10.1017/s026303460220227x.

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The problem of energy recuperator for a high current sheet electron beam used to drive a millimeter-waves generator is considered. There are two main obstacles to solving the problem. The first one is the presence of a magnetic field guiding beam electrons. The second obstacle is significant energy and angular spreads of the electrons in the waste beam. To overcome these obstacles, we suggest a novel scheme of a recuperator. The main idea of the proposed scheme is the use of a decelerating electrical field together with a guiding magnetic field that has longitudinal and spatial periodic transverse components. Resonance of a bounce electron motion with the cyclotron motion in this field gives a strong increase in the Larmour radius of electrons with the energy in a narrow interval. The decelerated electrons with the resonance energy fall away from the beam and are absorbed by a collector at a proper potential. It is shown that efficiency of this novel scheme can reach about 80% even if the sheet beam has a broad energy spectrum.

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Yoshida, Takaho, Takeshi Kawasaki, Junji Endo, Tadao Furutsu, Isao Matsui, Tsuyoshi Matsuda, Nobuyuki Osakabe, Akira Tonomura, and Koichi Kitazawa. "Development of a 1-MV Field-Emission Electron Microscope III. Electron Optical Design and Development of Field-Emission Electron Gun." Microscopy and Microanalysis 6, S2 (August 2000): 1142–43. http://dx.doi.org/10.1017/s1431927600038204.

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Bright and coherent electron beams have been opening new frontiers in science and technology. So far, we have developed several field-emission transmission electron microscopes (FE-TEM) with increasing accelerating voltages to provide higher beam brightness. By using a 200-kV FE-TEM and electron holography techniques, we directly confirmed the Aharonov-Bohm effect. A 350-kV FE-TEM equipped with a low-temperature specimen stage enabled us to observe moving vortices in superconductors.2 Most Recently, we have developed a new 1-MV FE-TEM with a newly designed FE gun to obtain an even brighter and more coherent electron beam.Electron beam brightness, Br, defined in Figure 1, is suitable for measuring the performance of electron guns, since both lens aberrations and mechanical/electrical vibrations contribute to a decrease in beam brightness, and beam coherency is proportional to (Br)1/2. Therefore, we optimized design of the illuminating system and its operation by maximizing the electron beam brightness.

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Matsuzawa, Hidenori, and Tetsuya Akitsu. "High‐pressure operation of a beam diode for relativistic electron beams." Journal of Applied Physics 63, no. 9 (May 1988): 4388–91. http://dx.doi.org/10.1063/1.340181.

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Fusayama, Takao. "High Pressure Operation of an Electron Beam Gun." Japanese Journal of Applied Physics 25, Part 2, No. 5 (May 20, 1986): L406—L408. http://dx.doi.org/10.1143/jjap.25.l406.

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Burdovitsin, V. A., and E. M. Oks. "Fore-vacuum plasma-cathode electron sources." Laser and Particle Beams 26, no. 4 (November 12, 2008): 619–35. http://dx.doi.org/10.1017/s0263034608000694.

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AbstractThis paper presents a review of physical principles, design, and performances of plasma-cathode direct current (dc) electron beam guns operated in so called fore-vacuum pressure (1–15 Pa). That operation pressure range was not reached before for any kind of electron sources. A number of unique parameters of the e-beam were obtained, such as electron energy (up to 25 kV), dc beam current (up 0.5 A), and total beam power (up to 7 kW). For electron beam generation at these relatively high pressures, the following special features are important: high probability of electrical breakdown within the accelerating gap, a strong influence of back-streaming ions on both the emission electrode and the emitting plasma, generation of secondary plasma in the beam propagation region, and intense beam-plasma interactions that lead in turn to broadening of the beam energy spectrum and beam defocusing. Yet other unique peculiarities can occur for the case of ribbon electron beams, having to do with local maxima in the lateral beam current density distribution. The construction details of several plasma-cathode electron sources and some specific applications are also presented.

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Воробьёв, М. С., П. В. Москвин, В. И. Шин, Т. В. Коваль, В. Н. Девятков, С. Ю. Дорошкевич, Н. Н. Коваль, М. С. Торба, and К. Т. Ашурова. "Отрицательная обратная связь по току в ускоряющем промежутке в источниках электронов с плазменным катодом." Журнал технической физики 92, no. 6 (2022): 883. http://dx.doi.org/10.21883/jtf.2022.06.52519.14-22.

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Using the example of an electron source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the cathode/emission plasma boundary and an open anode/beam plasma boundary, a mechanism is described for increasing the electrical strength of a high-voltage accelerating gap by introducing a series negative current feedback (NCF) in the accelerating interval, which makes it possible to level out uncontrolled bursts of the beam current during its pulse. The introduction of NCF is achieved by using a special electrode in the space of the plasma emitter connected through a resistance to the anode of the arc discharge, and the main task of which is to intercept accelerated ions penetrating into the emitter from the high-voltage accelerating gap, due to which the current of electron emission from the arc discharge plasma decreases by a value proportional to the ion current in the accelerating gap. Since most sources and accelerators of electrons with plasma cathodes based on discharges of various types have a similar principle of operation, the use of this method will not only expand the limiting parameters of the generated electron beams, but also increase the stability of the operation of such electron sources, and, accordingly, beam irradiation of various materials and products.

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Fetzer, R., W. An, A. Weisenburger, and G. Mueller. "Different operation regimes of cylindrical triode-type electron accelerator studied by PIC code simulations." Laser and Particle Beams 35, no. 1 (December 14, 2016): 33–41. http://dx.doi.org/10.1017/s0263034616000768.

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AbstractThe performance of the converging electron beam generated in cylindrical triodes is systematically studied by particle-in-cell code simulations. Depending on the cathode and grid potentials applied, different operation regimes are identified. For low voltages between cathode and grid, laminar flow and homogeneous beam energy density at the target (anode) is obtained. This applies both to the case of unipolar electron flow and to bipolar flow with counter-streaming ions. Hereby, the electron emission current is enhanced by about 50% for bipolar flow compared with unipolar flow. A further increase by about 20% is obtained when electron backscattering at the target is enhanced due to a change of target material from aluminum to tungsten. For cathode-grid voltages exceeding a critical value, laminar flow is replaced by non-laminar flow regimes. For unipolar electron beams, a virtual cathode forms between grid and target, which leads to an inhomogeneous power density at the target. For the specific geometry investigated and the cathode potential fixed at −120 kV, the cathode-grid voltage threshold for the formation of the virtual cathode is ~32 kV for Al targets and ~28 kV for W targets. For bipolar flow, the laminar flow regime already ends at cathode-grid voltages of ~23 kV (Al target) and ~20 kV (W target), respectively, and is replaced by magnetic insulation at the beam edge. For increasing cathode-grid voltage, the magnetically insulated region extends until beam pinching occurs.

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Han, Bumsoo, Jin Kyu Kim, Yuri Kim, Jang Seung Choi, and Kwang Young Jeong. "Operation of industrial-scale electron beam wastewater treatment plant." Radiation Physics and Chemistry 81, no. 9 (September 2012): 1475–78. http://dx.doi.org/10.1016/j.radphyschem.2012.01.030.

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Dattoli, Giuseppe, Emanuele Di Palma, Alberto Petralia, and Marcello Quattromini. "Electron Beam Transverse Longitudinal Dynamics for SASE FEL Operation." IEEE Journal of Quantum Electronics 49, no. 3 (March 2013): 267–73. http://dx.doi.org/10.1109/jqe.2013.2238889.

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13

Wang, Qingyuan, Shanfu Yu, Peijue Xun, Shenggang Liu, Kesong Hu, Yutao Chen, and Pinshan Wang. "First operation of a multi‐electron‐beam Cherenkov free‐electron laser oscillator." Applied Physics Letters 59, no. 19 (November 4, 1991): 2378–80. http://dx.doi.org/10.1063/1.106021.

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EFTHIMION, PHILIP C., ERIK GILSON, LARRY GRISHAM, PAVEL KOLCHIN, RONALD C. DAVIDSON, SIMON YU, and B. GRANT LOGAN. "ECR plasma source for heavy ion beam charge neutralization." Laser and Particle Beams 21, no. 1 (January 2003): 37–40. http://dx.doi.org/10.1017/s0263034602211088.

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Highly ionized plasmas are being considered as a medium for charge neutralizing heavy ion beams in order to focus beyond the space-charge limit. Calculations suggest that plasma at a density of 1–100 times the ion beam density and at a length ∼0.1–2 m would be suitable for achieving a high level of charge neutralization. An Electron Cyclotron Resonance (ECR) source has been built at the Princeton Plasma Physics Laboratory (PPPL) to support a joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 1–10 gauss. The goal is to operate the source at pressures ∼10−6 Torr at full ionization. The initial operation of the source has been at pressures of 10−4–10−1 Torr. Electron densities in the range of 108 to 1011 cm−3 have been achieved. Low-pressure operation is important to reduce ion beam ionization. A cusp magnetic field has been installed to improve radial confinement and reduce the field strength on the beam axis. In addition, axial confinement is believed to be important to achieve lower-pressure operation. To further improve breakdown at low pressure, a weak electron source will be placed near the end of the ECR source. This article also describes the wave damping mechanisms. At moderate pressures (> 1 mTorr), the wave damping is collisional, and at low pressures (< 1 mTorr) there is a distinct electron cyclotron resonance.

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Rodrigues, A. R. D., A. F. Craievich, and C. E. T. Gonçalves da Silva. "Commissioning and Operation of the First Brazilian Synchrotron Light Source." Journal of Synchrotron Radiation 5, no. 3 (May 1, 1998): 1157–61. http://dx.doi.org/10.1107/s0909049597018293.

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The synchrotron light source designed and constructed at the LNLS is composed of a 1.37 GeV electron storage ring and a 120 MeV linac for low-energy injection. The storage ring has been commissioned and has already reached the designed electron-beam energy, current and emittance. The electron lifetime is now 6 h at 60 mA, and is steadily increasing. Seven beamlines (TGM, SGM, SXS, XAFS, XRD, SAXS, PCr) have been constructed in parallel with the electron accelerators and are at present in operation. Beam time was allocated to 129 approved research projects for the second semester of 1997. A number of them are currently under way.

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Galatà, A., P. Francescon, C. Roncolato, G. Bisoffi, M. Ballan, L. Bellan, J. Bermudez, et al. "First beams from the 1+ source of the ADIGE injector for the SPES Project." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012069. http://dx.doi.org/10.1088/1742-6596/2244/1/012069.

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Abstract The ADIGE (Acceleratore Di Ioni a Grande carica Esotici) injector consists of an electrostatic 1+ beam line, equipped with ion sources able to produce a wide variety of beams, coupled to a magnetic beam line, where charge multiplication is accomplished by implementing an Electron Cyclotron Resonance (ECR) based charge breeder. The injector is totally integrated in the SPES (Selective Production of Exotic Species) beam line, to allow the post-acceleration of radioactive ions and is now in an advanced phase of installation. The electrostatic 1+beam line has been put into operation and is now producing beams from alkali metals. This contribution concerns the first results of the beam commissioning of this part of the injector, with the description of the initial debug phase and the solutions adopted to ensure a reliable and continuous operation. Preliminary results of the 1+ beam line characterization will be shown, with a comparison between simulated and measured emittances.

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Galatà, A., P. Francescon, C. Roncolato, G. Bisoffi, M. Ballan, L. Bellan, J. Bermudez, et al. "First beams from the 1+ source of the ADIGE injector for the SPES Project." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012069. http://dx.doi.org/10.1088/1742-6596/2244/1/012069.

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Abstract The ADIGE (Acceleratore Di Ioni a Grande carica Esotici) injector consists of an electrostatic 1+ beam line, equipped with ion sources able to produce a wide variety of beams, coupled to a magnetic beam line, where charge multiplication is accomplished by implementing an Electron Cyclotron Resonance (ECR) based charge breeder. The injector is totally integrated in the SPES (Selective Production of Exotic Species) beam line, to allow the post-acceleration of radioactive ions and is now in an advanced phase of installation. The electrostatic 1+beam line has been put into operation and is now producing beams from alkali metals. This contribution concerns the first results of the beam commissioning of this part of the injector, with the description of the initial debug phase and the solutions adopted to ensure a reliable and continuous operation. Preliminary results of the 1+ beam line characterization will be shown, with a comparison between simulated and measured emittances.

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Nonnenmacher, Toby, Titus-Stefan Dascalu, Robert Bingham, Chung Lim Cheung, Hin-Tung Lau, Ken Long, Jürgen Pozimski, and Colin Whyte. "Anomalous Beam Transport through Gabor (Plasma) Lens Prototype." Applied Sciences 11, no. 10 (May 11, 2021): 4357. http://dx.doi.org/10.3390/app11104357.

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An electron plasma lens is a cost-effective, compact, strong-focusing element that can ensure efficient capture of low-energy proton and ion beams from laser-driven sources. A Gabor lens prototype was built for high electron density operation at Imperial College London. The parameters of the stable operation regime of the lens and its performance during a beam test with 1.4 MeV protons are reported here. Narrow pencil beams were imaged on a scintillator screen 67 cm downstream of the lens. The lens converted the pencil beams into rings that show position-dependent shape and intensity modulation that are dependent on the settings of the lens. Characterisation of the focusing effect suggests that the plasma column exhibited an off-axis rotation similar to the m=1 diocotron instability. The association of the instability with the cause of the rings was investigated using particle tracking simulations.

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Zimek, Zbigniew. "Economical evaluation of radiation processing with high-intensity X-rays." Nukleonika 65, no. 3 (September 1, 2020): 167–72. http://dx.doi.org/10.2478/nuka-2020-0027.

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AbstractX-rays application for radiation processing was introduced to the industrial practice, and in some circumstances is found to be more economically competitive, and offer more flexibility than gamma sources. Recent progress in high-power accelerators development gives opportunity to construct and apply reliable high-power electron beam to X-rays converters for the industrial application. The efficiency of the conversion process depends mainly on electron energy and atomic number of the target material, as it was determined in theoretical predictions and confirmed experimentally. However, the lower price of low-energy direct accelerators and their higher electrical efficiency may also have certain influence on process economy. There are number of auxiliary parameters that can effectively change the economical results of the process. The most important ones are as follows: average beam power level, spare part cost, and optimal shape of electron beam and electron beam utilization efficiency. All these parameters and related expenses may affect the unit cost of radiation facility operation and have a significant influence on X-ray process economy. The optimization of X-rays converter construction is also important, but it does not depend on the type of accelerator. The article discusses the economy of radiation processing with high-intensity of X-rays stream emitted by conversion of electron beams accelerated in direct accelerator (electron energy 2.5 MeV) and resonant accelerators (electron energy 5 MeV and 7.5 MeV). The evaluation and comparison of the costs of alternative technical solutions were included to estimate the unit cost of X-rays facility operation for average beam power 100 kW.

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Kazakov, A. V., E. M. Oks, and N. A. Panchenko. "Influence of electron emission on operation of a constricted arc discharge in a pulsed forevacuum plasma-cathode electron source." Journal of Physics: Conference Series 2064, no. 1 (November 1, 2021): 012124. http://dx.doi.org/10.1088/1742-6596/2064/1/012124.

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Abstract The research of influence of electron emission and processes associated with the formation of a pulsed large-radius electron beam on operation of a constricted arc discharge, which forms emission plasma in a forevacuum plasma-cathode electron source, is presented. Processes, occurring in case of generation of the electron beam at forevacuum pressure range 3–20 Pa, provide lower operating voltage of the constricted arc discharge. The constricted arc voltage decreases with increasing pressure and increasing accelerating voltage. However, at pressure more than 15 Pa, the arc voltage decreases until a certain minimum value is reached, and then arc voltage is almost independent on pressure and accelerating voltage. This minimum value of the constricted arc voltage is on average 1.5–2 times higher as compared with voltage of the cathodic arc at the same discharge current. The observed decrease of operating voltage of the constricted arc is most likely caused by accelerated back-streaming ions, which move toward the emission electrode from beam-produced plasma. These accelerated ions partially penetrate into the hollow anode of discharge system through the mesh emission electrode and facilitate formation of the arc plasma, and thus provides lower voltage of the constricted arc.

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Boutet, Sébastien, Lutz Foucar, Thomas R. M. Barends, Sabine Botha, R. Bruce Doak, Jason E. Koglin, Marc Messerschmidt, et al. "Characterization and use of the spent beam for serial operation of LCLS." Journal of Synchrotron Radiation 22, no. 3 (April 11, 2015): 634–43. http://dx.doi.org/10.1107/s1600577515004002.

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X-ray free-electron laser sources such as the Linac Coherent Light Source offer very exciting possibilities for unique research. However, beam time at such facilities is very limited and in high demand. This has led to significant efforts towards beam multiplexing of various forms. One such effort involves re-using the so-called spent beam that passes through the hole in an area detector after a weak interaction with a primary sample. This beam can be refocused into a secondary interaction region and used for a second, independent experiment operating in series. The beam profile of this refocused beam was characterized for a particular experimental geometry at the Coherent X-ray Imaging instrument at LCLS. A demonstration of this multiplexing capability was performed with two simultaneous serial femtosecond crystallography experiments, both yielding interpretable data of sufficient quality to produce electron density maps.

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Chan, L. S., D. Tan, S. Saboohi, S. L. Yap, and C. S. Wong. "Operation of an electron beam initiated metallic plasma capillary discharge." Vacuum 103 (May 2014): 38–42. http://dx.doi.org/10.1016/j.vacuum.2013.12.003.

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Erck, R. A. "Observation of cryopump fluorescence during operation of electron‐beam evaporator." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 12, no. 5 (September 1994): 2931–32. http://dx.doi.org/10.1116/1.578968.

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Chikunov, V. V., B. A. Knyazev, V. S. Koidan, V. V. Konyukhov, S. V. Lebedev, K. I. Mekler, M. A. Shcheglov, and S. G. Voropajev. "Magnetic focusing of an intense microsecond relativistic electron beam." Laser and Particle Beams 3, no. 3 (August 1985): 259–62. http://dx.doi.org/10.1017/s0263034600001464.

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Experimental results are presented on the focusing of an intense microsecond relativistic electron beam. The beam is generated in a high-voltage quasi-planar diode (E = 600–800 keV, τ = 3–5 μsec). It is then magnetically – focused by longitudinal injection into a magnetic mirror. The total energy of the beam is about 50 kJ. The focusing chamber is filled with argon under a pressure varying from 3 × 10−5 to 1 torr. The results include investigations of beam focusing under various conditions, the dynamics of the return current in the plasma as well as the influence of the reflected beam electrons on the operation of the accelerator diode. A 20-fold focused beam with a 4 cm diameter, 46 kJ energy content, and current density up to 3 kA/cm2 was obtained.

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Joy, David C., and Dale E. Newbury. "Low Voltage Scanning Electron Microscopy." Microscopy and Microanalysis 7, S2 (August 2001): 762–63. http://dx.doi.org/10.1017/s1431927600029883.

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Low Voltage Scanning Electron Microscopy (LVSEM), defined as operation in the energy range below 5keV, has become perhaps the most important single operational mode of the SEM. This is because the LVSEM offers advantages in the imaging of surfaces, in the observation of poorly conducting and insulating materials, and for high spatial resolution X-ray microanalysis. These benefits all occur because a reduction in the energy E0 of the incident beam leads to a rapid fall in the range R of the electrons since R ∼ k.E01.66. The reduction in the penetration of the beam has important consequences. Firstly, volume of the specimen that is sampled by the beam shrinks dramatically (varying as about E05 ) and so the information generated by the beam is confined to the surface of the sample. Secondly, the yield 8 of secondary electrons is increased from a typical value of 0.1 at 20keV to a value that may be in excess of 1.0 at 1keV.

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Joy, David C., and Dale E. Newbury. "Low Voltage Scanning Electron Microscopy." Microscopy Today 10, no. 2 (March 2002): 22–23. http://dx.doi.org/10.1017/s1551929500057813.

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Low Voltage Scanning Electron Microscopy (LVSEM), defined as operation in the energy range below 5 keV, has become perhaps the most important single operational mode of the SEM. This is because the LVSEM offers advantages in the imaging of surfaces, in the observation of poorly conducting and insulating materials, and for high spatial resolution X-ray microanalysis. These benefits all occur because a reduction in the energy Eo of the incident beam leads to a rapid fall in the range R of the electrons since R ∼k.E01.66. The reduction in the penetration of the beam has important consequences.

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Ferrario, Massimo, and Tsumoru Shintake. "High Performance Electron Injectors." Reviews of Accelerator Science and Technology 03, no. 01 (January 2010): 221–35. http://dx.doi.org/10.1142/s1793626810000464.

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Fourth generation light sources based on high gain free electron lasers require production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake field effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, and hence the design of the injector and its operation constitute the leading edge for high quality beam production and for the success of the future light sources. RF and DC guns, cathode materials, laser pulse shaping and sub-picosecond synchronization systems are evolving toward a mature technology to produce high quality and stable beams. Nevertheless, reduction of thermal emittance, damping of emittance oscillations and bunch compression are still the main issues and challenges for injector designs. With the advent of energy recovery linacs, superconducting RF guns have been also considered in many new projects as a possible electron source operating in CW mode. An overview of recent advancements and future perspectives of high performance electron injectors are presented in this article.

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Abbasi, E., S. Jafari, and R. Hedayati. "Interaction of a relativistic dense electron beam with a laser wiggler in a vacuum: self-field effects on the electron orbits and free-electron laser gain." Journal of Synchrotron Radiation 23, no. 6 (October 10, 2016): 1282–95. http://dx.doi.org/10.1107/s1600577516012601.

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Employing laser wigglers and accelerators provides the potential to dramatically cut the size and cost of X-ray light sources. Owing to recent technological developments in the production of high-brilliance electron beams and high-power laser pulses, it is now conceivable to make steps toward the practical realisation of laser-pumped X-ray free-electron lasers (FELs). In this regard, here the head-on collision of a relativistic dense electron beam with a linearly polarized laser pulse as a wiggler is studied, in which the laser wiggler can be realised using a conventional quantum laser. In addition, an external guide magnetic field is employed to confine the electron beam against self-fields, therefore improving the FEL operation. Conditions allowing such an operating regime are presented and its relevant validity checked using a set of general scaling formulae. Rigorous analytical solutions of the dynamic equations are provided. These solutions are verified by performing calculations using the derived solutions and well known Runge–Kutta procedure to simulate the electron trajectories. The effects of self-fields on the FEL gain in this configuration are estimated. Numerical calculations indicate that in the presence of self-fields the sensitivity of the gain increases in the vicinity of resonance regions. Besides, diamagnetic and paramagnetic effects of the wiggler-induced self-magnetic field cause gain decrement and enhancement for different electron orbits, while these diamagnetic and paramagnetic effects increase with increasing beam density. The results are compared with findings of planar magnetostatic wiggler FELs.

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BOICHENKO, A. M., S. I. YAKOVLENKO, and V. F. TARASENKO. "Electron beam-excited Xe excilamp's optimal characteristics." Laser and Particle Beams 18, no. 4 (October 2000): 655–60. http://dx.doi.org/10.1017/s0263034600184095.

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Calculations of optimal parameters for the e-beam excited Xe spontaneous radiation source (excilamp) at λ ∼ 172 nm have been done. There have been defined optimal values of gas density and specific excitation power. Gas temperature dependence of radiation conversion efficiency related to the injected media energy have been also computed. It has been shown that there is an optimum in excitation pulse duration at frequency operation mode.

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Laszczyk, Karolina Urszula. "Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions." Micromachines 11, no. 3 (February 29, 2020): 260. http://dx.doi.org/10.3390/mi11030260.

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In the first decade of our century, carbon nanotubes (CNTs) became a wonderful emitting material for field-emission (FE) of electrons. The carbon nanotube field-emission (CNT-FE) cathodes showed the possibility of low threshold voltage, therefore low power operation, together with a long lifetime, high brightness, and coherent beams of electrons. Thanks to this, CNT-FE cathodes have come ahead of increasing demand for novel self-sustaining and miniaturized devices performing as X-ray tubes, X-ray spectrometers, and electron microscopes, which possess low weight and might work without the need of the specialized equipped room, e.g., in a harsh environment and inaccessible-so-far areas. In this review, the author discusses the current state of CNT-FE cathode research using CNT suspensions. Included in this review are the basics of cathode operation, an evaluation, and fabrication techniques. The cathodes are compared based on performance and correlated issues. The author includes the advancement in field-emission enhancement by postprocess treatments, incorporation of fillers, and the use of film coatings with lower work functions than that of CNTs. Each approach is discussed in the context of the CNT-FE cathode operating factors. Finally, we discuss the issues and perspectives of the CNT-FE cathode research and development.

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Teng, Y., C. H. Chen, H. Shao, J. Sun, Z. M. Song, R. Z. Xiao, and Z. Y. Du. "Design and efficient operation of a coaxial RBWO." Laser and Particle Beams 31, no. 2 (June 2013): 321–31. http://dx.doi.org/10.1017/s0263034612001061.

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AbstractCoaxial relativistic backward wave oscillator with the rippled inner conductor not only increases the output efficiency but also results in the serious phenomenon of pulse shortening in experiments. Our research indicates that the two main mechanisms leading to the pulse shortening are the electron beam interruption and combining effects of the explosive field electron emission and the secondary electron multipactor on the surface of the slow-wave structure. In order to enhance its power capacity the electrodynamic structure is modified by detailed analysis of the field distribution in the coaxial slow-wave structure. The appropriate resonant reflector and the electron collector are developed for the application of the coaxial relativistic backward wave oscillator. A series of surface treatment is applied to enhance the power capacity of the coaxial RBWO. In the experiment, the microwave pulse duration is increased from less than 10 ns to 20 ns, and the output efficiency is enhanced from less than 20% to 34% employing the electron beam pulse of the full width at half maximum 28 ns. The peak power of 1.01 GW at the frequency of 7.4 GHz is achieved. It is found that the output efficiency of the coaxial RBWO is likely to be advanced if its power capacity can be boosted further.

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Hecht, M. H., L. D. Bell, and W. J. Kaiser. "Ballistic Electron Emission Microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 613–14. http://dx.doi.org/10.1017/s0424820100181841.

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Ballistic Electron Emission Microscopy (BEEM) is a scanning-tunneling-microscopy-based technique which gives a plan view, nanometer scale image of electronic properties of a buried interface. Among the properties which can be imaged are barrier height, the edges of multiple conduction and valence bands, and carrier scattering. These properties can be correlated with strain, defects, and stoichiometry variations at the interface. A topographic image of the sample surface is aquired simultaneously with the interface image. BEEM data has been reported from six laboratories to date, including images of Au/Si, Au/GaAs, NiSi2/Si, and Au/CdTe. Several new systems, some designed for ultra-high-vacuum operation, are under construction.In the simplest implementation, electrons or holes are injected from a tunnel tip into the metal electrode of a metal-semiconductor diode (figure 1). The carriers are ballistically transported across the electrode and, if momentum, energy, and scattering criteria are satisfied, are collected in the semiconductor base. Momentum conservation requires the ballistic electron or hole beam to cross the interface within a small cone of solid angle, and hence the collected current only reflects injection into a small region of the Brillouin zone. This small critical angle cone is responsible for the high spatial resolution of BEEM. By varying the potential of the initial injected beam (i.e. tip voltage with respect to electrode), the electronic dispersion relation of the substrate can be spectroscopically probed.

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Postek, M. T., and A. E. Vladár. "Is Low Accelerating Voltage Always the Best for Semiconductor Inspection and Metrology?" Microscopy Today 12, no. 1 (January 2004): 46–47. http://dx.doi.org/10.1017/s1551929500051865.

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Low accelerating voltage operation is an excellent mode of scanning electron microscopy and it is extensively used for measurements in semiconductor production. The beam penetration is small, and if properly applied, the specimen charging is kept at acceptable levels. But, is this always enough? Today, the scanning electron microscope (SEM) is being used in photomask metrology and imaging where charging is excessive. Charging is difficult to quantify and control as it varies greatly with instruments, operating conditions and sample. Therefore, it is also very difficult to model accurately. For accurate metrology charging must be overcome because the dynamic charging of the sample deflects the electron beam from its intended position and the intensity of the induced signal may vary uncontrollably. Deflection of the electron beam of even a few nanometers potentially results in a measurement error that is significant to modern semiconductor production.

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Cumings, John, A. Zettl, and M. R. McCartney. "Carbon Nanotube Electrostatic Biprism: Principle of Operation and Proof of Concept." Microscopy and Microanalysis 10, no. 4 (August 2004): 420–24. http://dx.doi.org/10.1017/s1431927604040759.

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During in situ transmission electron microscopy (TEM) field emission experiments, carbon nanotubes are observed to strongly diffract the imaging TEM electron beam. We demonstrate that this effect is identical to that of a standard electrostatic biprism. We also demonstrate that the nanotube biprism can be used to capture electron-holographic information.

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Stevens, D., T. J. Babij, J. R. Machacek, and J. P. Sullivan. "Low energy electron scattering from pyridine using a Surko trap and beam." Journal of Physics B: Atomic, Molecular and Optical Physics 54, no. 23 (December 8, 2021): 235202. http://dx.doi.org/10.1088/1361-6455/ac3fc0.

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Abstract This paper presents measurements of low energy electron scattering from pyridine. The low energy positron beamline at the Australian National University was used for these measurements, with a change in operational parameters allowing for the measurement of electron scattering processes. We have collected data for the low energy total cross section for electron scattering, as well as measurements of the differential cross sections for electrons up to 3 eV impact energy. The operation of the beamline will be briefly outlined and data are compared to R-matrix and Schwinger multichannel theoretical calculations, as well as previous experimental data.

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Çetin, Gürkan, Ahmet Özkara, Emin Tireli, Özge Köner, and Kaya Süzer. "Myocardial Ischemia after Cabrol Operation." Asian Cardiovascular and Thoracic Annals 13, no. 2 (June 2005): 187–89. http://dx.doi.org/10.1177/021849230501300221.

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A 33-year-old woman who had undergone a Cabrol-type aortic root replacement for acute aortic dissection during labor 27 months ago was admitted with chest pain. Electron-beam tomography and coronary angiography showed stenosis at the level of the anastomosis. Urgent coronary revascularization was performed using bilateral internal mammary artery grafts. Although graft occlusion after the Cabrol procedure is an infrequent complication, it should be considered during follow-up.

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Dřímal, Daniel. "Electron Beam Welding of Gear Wheels by Splitted Beam." Research Papers Faculty of Materials Science and Technology Slovak University of Technology 22, no. 34 (June 1, 2014): 35–41. http://dx.doi.org/10.2478/rput-2014-0025.

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

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Reiche, Sven, and Eduard Prat. "Two-color operation of a free-electron laser with a tilted beam." Journal of Synchrotron Radiation 23, no. 4 (May 16, 2016): 869–73. http://dx.doi.org/10.1107/s1600577516007189.

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With the successful operation of free-electron lasers (FELs) as user facilities there has been a growing demand for experiments with two photon pulses with variable photon energy and time separation. A configuration of an undulator with variable-gap control and a delaying chicane in the middle of the beamline is proposed. An injected electron beam with a transverse tilt will only yield FEL radiation for the parts which are close to the undulator axis. This allows, after re-aligning and delaying the electron beam, a different part of the bunch to be used to produce a second FEL pulse. This method offers independent control in photon energy and delay. For the parameters of the soft X-ray beamline Athos at the SwissFEL facility the photon energy tuning range is a factor of five with an adjustable delay between the two pulses from −50 to 950 fs.

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39

Gleizer, S., D. Yarmolich, J. Felsteiner, Ya E. Krasik, P. Nozar, and C. Taliani. "Electron beam and plasma modes of a channel spark discharge operation." Journal of Applied Physics 106, no. 7 (October 2009): 073301. http://dx.doi.org/10.1063/1.3234376.

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40

Udrea, Mircea. "High‐repetition‐rate operation of a double‐discharge electron beam generator." Optical Engineering 35, no. 5 (May 1, 1996): 1330. http://dx.doi.org/10.1117/1.600622.

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41

Khurgin, J., W. Seemungal, S. Colak, and A. Hebling. "Single longitudinal mode operation of the electron-beam-pumped semiconductor laser." IEEE Journal of Quantum Electronics 22, no. 8 (August 1986): 1158–61. http://dx.doi.org/10.1109/jqe.1986.1073099.

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42

Tiddi, William, Anna Elsukova, Marco Beleggia, and Anpan Han. "Organic ice resists for 3D electron-beam processing: Instrumentation and operation." Microelectronic Engineering 192 (May 2018): 38–43. http://dx.doi.org/10.1016/j.mee.2018.01.021.

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43

Chen, Yun Xia, Guo Hua Li, and Xiao Jing Wang. "Predictive of Electron Beam Focus Position by Metal Powder Temperature." Applied Mechanics and Materials 217-219 (November 2012): 1779–85. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1779.

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The equipment for measuring electron beam (EB) focus in electron beam produced by the effect of extremum temperature of powder molten pool caused by the interactive effect of electron beam with metal powder is described. The principle of operation of apparatus and examples of EB characteristics are presented. During electron beam processing, the mechanical analysis of metal powder molten pool temperature following focusing current are studied. As a result, the transferring point of critical energy density described by the peak of metal powder pool temperature can be obtained. Based on the temperature characteristics of critical energy density, the measuring concept of dynamic focal spot of electron beam is put forward in the paper. The method of measuring dynamic focal spot of electron beam will provide a new possibility for 3D scanning prototyping through changing focus position of EB.

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44

Nikiforov, D. A., A. V. Petrenko, S. L. Sinitsky, P. A. Bak, D. I. Skovorodin, P. V. Logachev, K. I. Zhivankov, et al. "Investigation of high current electron beam dynamics in linear induction accelerator for creation of a high-power THz radiation source." Journal of Instrumentation 16, no. 11 (November 1, 2021): P11024. http://dx.doi.org/10.1088/1748-0221/16/11/p11024.

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Abstract The work addresses the use of electron beam produced by the linear induction accelerator to generate terahertz radiation pulses of 100 MW power level based on a free electron laser scheme. The beam parameters required for efficient generation are given. The features of transverse beam dynamics when transporting the beam through the linac are investigated. Emphasis is put on the electron injector which geometry and operation parameters mainly determine the beam characteristics at the linac exit. Most of the possible factors contributing to the beam emittance gain in the accelerator are considered. The obtained analytical estimates are compared to the numerical simulation results. The experimental results on compressing and transporting the beam having the electron energy of 5 MeV and the current of 1 kA in the transport system of free electron laser are presented.

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45

Endo, J., T. Kawasaki, T. Masuda, and A. Tonomura. "Development of 350-KV holography electron microscope equipped with magnetic type field-emission electron gun." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 104–5. http://dx.doi.org/10.1017/s0424820100152495.

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A field-emission electron gun is one of the most epoch-making technologies in an electron microscopic world. In a transmission electron microscope, a high brightness of this beam has been effectively employed for electron-holographic measurements, though the value is not still high enough. Development of a higher brightness beam will promise to open up unattained application possibilities of electron holography such as high resolution and high sensitivity interferometry.We developed the field emission electron microscope for electron holographic applications. Special attentions were paid for high brightness, large beam current and easy operation. Figure 1 is a schematic diagram of the electron gun. In order not to deteriorate the original high-brightness feature of the beam by the aberrations in the gun and the condenser lenses, a magnetic lens was installed between the tip and the extraction anode so that the total aberration effect might be minimized. Field emitted electron beam is converged by the magnetic and the electrostatic lenses, and accelerated in a ten-stage accelerator which is made of porcelain.

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46

Scott, R. H., J. McLain, and R. C. Vondrasek. "Production of C-14 and stable ion beams at the Argonne Tandem Linac Accelerator System with the ECR3 ion source." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012068. http://dx.doi.org/10.1088/1742-6596/2244/1/012068.

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Abstract The Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) paused production of carbon-14 ion beams with the removal of the Tandem Van de Graaff in 2013. Installation of ECR3, an Electron Cyclotron Resonance Ion Source, returned that production capability to ATLAS, with the first C-14 beam delivered in December 2020. Information is presented on C-14 beam current, gas consumption and N-14 filtering techniques using stripping foils at different sections of ATLAS. ECR3 also fulfilled the operational goal of adding flexibility to ATLAS stable beam production capabilities. Beneficial impacts to ATLAS operation, beam development and experimental programs are discussed.

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47

Scott, R. H., J. McLain, and R. C. Vondrasek. "Production of C-14 and stable ion beams at the Argonne Tandem Linac Accelerator System with the ECR3 ion source." Journal of Physics: Conference Series 2244, no. 1 (April 1, 2022): 012068. http://dx.doi.org/10.1088/1742-6596/2244/1/012068.

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Abstract The Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) paused production of carbon-14 ion beams with the removal of the Tandem Van de Graaff in 2013. Installation of ECR3, an Electron Cyclotron Resonance Ion Source, returned that production capability to ATLAS, with the first C-14 beam delivered in December 2020. Information is presented on C-14 beam current, gas consumption and N-14 filtering techniques using stripping foils at different sections of ATLAS. ECR3 also fulfilled the operational goal of adding flexibility to ATLAS stable beam production capabilities. Beneficial impacts to ATLAS operation, beam development and experimental programs are discussed.

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Koch, Andreas, Johannes Risch, Wolfgang Freund, Theophilos Maltezopoulos, Marc Planas, and Jan Grünert. "Operation of photon diagnostic imagers for beam commissioning at the European XFEL." Journal of Synchrotron Radiation 26, no. 5 (August 19, 2019): 1489–95. http://dx.doi.org/10.1107/s1600577519008737.

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X-ray photon beam diagnostic imagers are located at 24 positions in the European XFEL beam transport system to characterize the X-ray beam properties, and to give feedback for tuning and optimization of the electron acceleration and orbit, the undulators, and the X-ray optics. One year of commissioning allowed experience to be gained with these imagers, which will be reported here. The sensitive Spontaneous Radiation imager is useful for various investigations in spontaneous radiation mode: for undulator adjustments and for low-signal imaging applications. The high-resolution Free-Electron Laser imager, 10 µm spatial resolution, is extensively used for the monitoring of beam position, spot size and shape, gain curve measurements, and also for beam-intensity monitoring. The wide field-of-view pop-in monitors (up to 200 mm) are regularly used for alignment and tuning of the various X-ray optical components like mirrors, slits and monochromators, and also for on-line beam control of a stable beam position at the instruments. The Exit Slit imager after the soft X-ray monochromator provides spectral information of the beam together with multi-channel plate based single-pulse gating. For particular use cases, these special features of the imagers are described. Some radiation-induced degradation of scintillators took place in this initial commissioning phase, providing useful information for better understanding of damage thresholds. Visible-light radiation in the beam pipe generated by upstream bending magnets caused spurious reflections in the optical system of some of the imagers which can be suppressed by aluminium-coated scintillating screens.

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Kärtner, Franz X. "Terahertz accelerator based electron and x-ray sources." Terahertz Science and Technology 13, no. 1 (March 2020): 22–31. http://dx.doi.org/10.1051/tst/2020131022.

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The generation and use of THz radiation for electron acceleration and manipulation of electron bunches has progressed over the last decade to a level where practical devices for THz guns, acceleration and a wide range of beam manipulations have become possible. Here, we present our progress on generation of single-cycle THz pulses at the two-hundred micro-Joule level to drive advanced acceleration and beam manipulation devices. Specifically, we use pulses centered at 0.3 THz to power a segmented terahertz electron accelerator and manipulator (STEAM) capable of performing multiple high-field operations on the 6D-phase-space of ultrashort electron bunches. Using this STEAM device, we demonstrate record THz-acceleration of >60 keV, streaking with <10 𝑓s resolution, focusing with >2 kT/m strength, compression to ~100 𝑓s as well as real-time switching between these modes of operation. The STEAM device demonstrates the feasibility of THz-based electron accelerators, manipulators and diagnostic tools enabling science beyond current resolution frontiers with transformative impact.

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Pan, M., K. Ishizuka, C. E. Meyer, O. L. Krivanek, J. Sasakit, and Y. Kimurat. "Progress in Computer Assisted Electron Microscopy." Microscopy and Microanalysis 3, S2 (August 1997): 1093–94. http://dx.doi.org/10.1017/s1431927600012356.

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All the lenses, deflectors and stigmators of contemporary electron microscopes are controlled digitally by an internal computer. Control through RS232 serial interface by an external computer has also become a standard feature. This external control has made so-called computer assisted electron microscopy (CAEM) possible and practical. We are developing a CAEM system with two objectives: (1) to free inexperienced microscopists from technical details of operating an electron microscope, especially transmission electron microscopes (TEM); (2) to assist experienced microscopists to operate their microscopes with higher accuracy and efficiency. The features include automated and/or assisted standard operations in focusing, stigmating, and aligning the microscope, and also sophisticated tuning that requires the evaluation of subtle changes in image features such as aligning the incident electron beam direction in the presence of 3-fold astigmatism in objective lens. CAEM can further assist operators in selecting areas or objects and taking images/diffraction/energy spectrum with all the parameters well controlled and catalogued together, thus not only enabling ease-of-use and high accuracy in operation but also yielding more information on the specimen.

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Journal articles on the topic 'Electron beam operation'

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