Zeitschriftenartikel: „High-charge electron beams“

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Maitrallain, A., E. Brunetti, M. J. V. Streeter, B. Kettle, R. Spesyvtsev, G. Vieux, M. Shahzad et al. „Parametric study of high-energy ring-shaped electron beams from a laser wakefield accelerator“. New Journal of Physics 24, Nr. 1 (01.01.2022): 013017. http://dx.doi.org/10.1088/1367-2630/ac3efd.

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Abstract Laser wakefield accelerators commonly produce on-axis, low-divergence, high-energy electron beams. However, a high charge, annular shaped beam can be trapped outside the bubble and accelerated to high energies. Here we present a parametric study on the production of low-energy-spread, ultra-relativistic electron ring beams in a two-stage gas cell. Ring-shaped beams with energies higher than 750 MeV are observed simultaneously with on axis, continuously injected electrons. Often multiple ring shaped beams with different energies are produced and parametric studies to control the generation and properties of these structures were conducted. Particle tracking and particle-in-cell simulations are used to determine properties of these beams and investigate how they are formed and trapped outside the bubble by the wake produced by on-axis injected electrons. These unusual femtosecond duration, high-charge, high-energy, ring electron beams may find use in beam driven plasma wakefield accelerators and radiation sources.

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Hwang, D. M., Y. A. Tkachenko und J. C. M. Hwang. „High-resolution charge collection microscopy with high-voltage electron beams“. Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 954–55. http://dx.doi.org/10.1017/s0424820100172504.

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Electron-beam-induced-current (EBIC) microscopy has the unique capability of simultaneously providing structural and transport characteristics of semiconductors. However, EBIC is traditionally performed inside an SEM with less than 40 keV electron beam energy. As the result, the applications of traditional EBIC for semiconductor device characterization are limited by either probing depth (0.02 ~0.05 μm with 2 ~5 keV electron beams) or spatial resolution (1-2 um with 20 ~40 keV electron beams). To achieve useful resolution for studying the interface effects critical to today's submicron devices, one would have to prepare the samples by either removing the passivation/metallization layers or making cross sections. In this paper, we report a breakthrough in the art of EBIC using high-voltage electron beams (200 keV and higher) to improve the spatial resolution and probing depth simultaneously. Adopting a JEOL 4000FX AEM for EBIC imaging, a spatial resolution of 0.05 um was demonstrated from structures 0.5 um beneath the surface. Using this technique, we have identified a facet degradation mechanism in strained quantum well laser diodes and hot-electroninduced defects in GaAs metal-semiconductor field-effect transistors (MESFETs).

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DEVYATKOV, V. N., N. N. KOVAL, P. M. SCHANIN, V. P. GRIGORYEV und T. V. KOVAL. „Generation and propagation of high-current low-energy electron beams“. Laser and Particle Beams 21, Nr. 2 (April 2003): 243–48. http://dx.doi.org/10.1017/s026303460321212x.

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High-current electron beams with a current density of up to 100 A/cm2 generated by a plasma-cathode gas-filled diode at low accelerating voltages are studied. Two types of gas discharges are used to produce plasma in the cathode. With glow and arc discharges, beam currents of up to 150 A and 400 A, respectively, have been obtained at an accelerating voltage of 16 kV and at a pressure of 1–3·10−2 Pa in the acceleration gap. The ions resulting from ionization of gas molecules by electrons of the beam neutralize the beam charge. The charge-neutralized electron beam almost without losses is transported over a distance of 30 cm in a drift channel which is in the axial magnetic field induced by Helmholtz coils. The results of calculations for the motion of electrons of the charge-neutralized beam with and without axial external field are presented and compared with those of experiments.

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Hue, Céline S., Yang Wan, Eitan Y. Levine und Victor Malka. „Control of electron beam current, charge, and energy spread using density downramp injection in laser wakefield accelerators“. Matter and Radiation at Extremes 8, Nr. 2 (01.03.2023): 024401. http://dx.doi.org/10.1063/5.0126293.

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Density downramp injection has been demonstrated to be an elegant and efficient approach for generating high-quality electron beams in laser wakefield accelerators. Recent studies have demonstrated the possibilities of generating electron beams with charges ranging from tens to hundreds of picocoulombs while maintaining good beam quality. However, the plasma and laser parameters in these studies have been limited to specific ranges or attention has been focused on separate physical processes such as beam loading, which affects the uniformity of the accelerating field and thus the energy spread of the trapped electrons, the repulsive force from the rear spike of the bubble, which reduces the transverse momentum p⊥ of the trapped electrons and results in small beam emittance, and the laser evolution when traveling in the plasma. In this work, we present a comprehensive numerical study of downramp injection in the laser wakefield, and we demonstrate that the current profile of the injected electron beam is directly correlated with the density transition parameters, which further affects the beam charge and energy evolution. By fine-tuning the plasma density parameters, electron beams with high charge (up to several hundreds of picocoulombs) and low energy spread (around 1% FWHM) can be obtained. All these results are supported by large-scale quasi-three-dimensional particle-in-cell simulations. We anticipate that the electron beams with tunable beam properties generated using this approach will be suitable for a wide range of applications.

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Niu, K., P. Mulser und L. Drska. „Beam generations of three kinds of charged particles“. Laser and Particle Beams 9, Nr. 1 (März 1991): 149–65. http://dx.doi.org/10.1017/s0263034600002391.

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Analyses are given for beam generations of three kinds of charged particles: electrons, light ions, and heavy ions. The electron beam oscillates in a dense plasma irradiated by a strong laser light. When the frequency of laser light is high and its intensity is large, the acceleration of oscillating electrons becomes large and the electrons radiate electromagnetic waves. As the reaction, the electrons feel a damping force, whose effect on oscillating electron motion is investigated first. Second, the electron beam induces the strong electromagnetic field by its self-induced electric current density when the electron number density is high. The induced electric field reduces the oscillation motion and deforms the beam.In the case of a light ion beam, the electrostatic field, induced by the beam charge, as well as the electromagnetic field, induced by the beam current, affects the beam motion. The total energy of the magnetic field surrounding the beam is rather small in comparison with its kinetic energy.In the case of heavy ion beams the beam charge at the leading edge is much smaller in comparison with the case of light ion beams when the heavy ion beam propagates in the background plasma. Thus, the induced electrostatic and electromagnetic fields do not much affect the beam propagation.

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Ma, Yong, Jiarui Zhao, Yifei Li, Dazhang Li, Liming Chen, Jianxun Liu, Stephen J. D. Dann et al. „Ultrahigh-charge electron beams from laser-irradiated solid surface“. Proceedings of the National Academy of Sciences 115, Nr. 27 (18.06.2018): 6980–85. http://dx.doi.org/10.1073/pnas.1800668115.

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Compact acceleration of a tightly collimated relativistic electron beam with high charge from a laser–plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from gases and vacuum laser acceleration from solids, often produce electron beams either with low charge or with large divergence angles. In this work, we report the generation of highly collimated electron beams with a divergence angle of a few degrees, nonthermal spectra peaked at the megaelectronvolt level, and extremely high charge (∼100 nC) via a powerful subpicosecond laser pulse interacting with a solid target in grazing incidence. Particle-in-cell simulations illustrate a direct laser acceleration scenario, in which the self-filamentation is triggered in a large-scale near–critical-density plasma and electron bunches are accelerated periodically and collimated by the ultraintense electromagnetic field. The energy density of such electron beams in high-Z materials reaches to ∼1012 J/m3, making it a promising tool to drive warm or even hot dense matter states.

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Lai, P. W., K. N. Liu, D. K. Tran, S. W. Chou, H. H. Chu, S. H. Chen, J. Wang und M. W. Lin. „Laser wakefield acceleration of 10-MeV-scale electrons driven by 1-TW multi-cycle laser pulses in a sub-millimeter nitrogen gas cell“. Physics of Plasmas 30, Nr. 1 (Januar 2023): 010703. http://dx.doi.org/10.1063/5.0131155.

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By focusing conventional 1-TW 40-fs laser pulses into a dense 450- μm-long nitrogen gas cell, we demonstrate the feasibility of routinely generating electron beams from laser wakefield acceleration (LWFA) with primary energies scaling up to 10 MeV and a high charge in excess of 50 pC. When electron beams are generated with a charge of ≈30 pC and a beam divergence of ≈40 mrad from the nitrogen cell having a peak atom density of [Formula: see text] cm−3, increasing the density inside the cell by 25%—controlled by tuning the backing pressure of fed nitrogen gas—can induce defocusing of the pump pulse that leads to a twofold increase in the output charge but with a trade-off in beam divergence. Therefore, this LWFA scheme has two preferred regimes for acquiring electron beams with either lower divergence or higher beam charge depending on a slight variation of the gas/plasma density inside the cell. Our results identify the high potential for implementing sub-millimeter nitrogen gas cells in the future development of high-repetition-rate LWFA driven by sub-TW or few-TW laser pulses.

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Metel, Alexander, Enver Mustafaev, Yury Melnik und Khaled Hamdy. „Generation of Electron and Fast Atom Beams by a Grid Immersed in Plasma“. EPJ Web of Conferences 248 (2021): 04001. http://dx.doi.org/10.1051/epjconf/202124804001.

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We present a new method of product processing with beams of accelerated electrons and fast neutral atoms, which are generated by an immersed in plasma grid under a high negative voltage of 5 kV. The electrons appear due to secondary emission from the grid surface provoked by its bombardment with ions accelerated from the plasma. At the gas pressure not exceeding 0.1 Pa the ions with energy of 5 keV reach the grid without collisions in the space charge sheaths near its surface and their current in the grid circuit is by 2-3 times lower than the electron current. At higher pressures accelerated ions due to charge exchange collisions in the sheaths turn into fast neutral atoms leaving the sheaths and forming the beams. With the pressure increasing, the electron beam current diminishes and the current of fast atom beam grows.

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Lapierre, A., H. J. Son, R. Ringle, S. Schwarz und A. C. C. Villari. „High-Current Capability and Upgrades of the EBIS/T Charge-Breeding System in the Reaccelerator at the Facility for Rare-Isotope Beams“. Journal of Physics: Conference Series 2743, Nr. 1 (01.05.2024): 012063. http://dx.doi.org/10.1088/1742-6596/2743/1/012063.

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Abstract The Reaccelerator (ReA) of the Facility for Rare-Isotope Beams (FRIB) at Michigan State University uses a Beam Cooler/Buncher (BCB) and an Electron-Beam Ion Trap (EBIT) as a charge-breeding injector system. The rare isotopes produced by In-flight Separation are selected by the Advanced Rare Isotope Separator (ARIS) and stopped in a helium gas cell. Long-lived and stable-isotope beams can also be extracted from a Batch-Mode Ion Source (BMIS). The continuous beams transported at low energy to ReA are injected into the BCB. The pulsed beams are then injected into the EBIT, charge bred, ejected, and accelerated by ReA’s LINAC. The EBIT electron current (300 - 600 mA) is a factor that limits its capacity to ∼2×1010 elementary charges, which restricts the maximum EBIT-extracted rates to less than 2×1010 particles per second for light ions. An upgrade of the EBIT electron gun is expected to provide 2 A in current. In parallel, a High-Current Electron-Beam Ion Source (HCEBIS) is being commissioned. The HCEBIS can presently provide an electron current of 2 A. An upgrade will increase the current to 4 A. The implementation of these two upgrades is expected to allow for maximum rates to be ∼1011 pps, compatible with FRIB projected rates and user demands. We review the high-current capabilities and upgrades of ReA’s charge-breeding system.

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Son, Hyock-Jun, Alain Lapierre, Stefan Schwarz und Antonio C. C. Villari. „Status of the High-Current Electron-Beam Ion Source Charge Breeder for the Facility for Rare-Isotope Beams“. Journal of Physics: Conference Series 2743, Nr. 1 (01.05.2024): 012046. http://dx.doi.org/10.1088/1742-6596/2743/1/012046.

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Abstract The Reaccelerator (ReA) of the Facility for Rare-Isotope Beams (FRIB) employs an Electron-Beam Ion Trap (EBIT) as a charge breeder to reaccelerate rare-isotope beams up to 12 MeV/u. The ReA EBIT produces an electron current of 300 – 600 mA. The maximum trap capacity of the ReA EBIT is 1010 elementary charges. FRIB production rates are expected to exceed 1010 particles/s in some cases in the future. There is also a user demand for reaccelerated stable-isotope beams of more than 1010 pps. To handle these rates and provide redundancy, a High Current Electron-Beam Ion Source (HCEBIS) has been built and is now being commissioned. An electron-beam current of 2 A with a 50 % duty cycle has been transported through a 4-T field. An upcoming upgrade to increase the electron-beam current up to 4 A will allow for a maximum trap capacity of 2.4×1011 elementary charges. We present the status of the HCEBIS, including the results of the electron-beam commissioning and systematic studies.

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Shang, Tianyi, und Weidong Ding. „Influence of gas pressure and gas type on pseudospark electron beam“. Journal of Instrumentation 18, Nr. 09 (01.09.2023): P09045. http://dx.doi.org/10.1088/1748-0221/18/09/p09045.

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Abstract Pseudospark discharge is a discharge that occurs in the left band of the Paschen curve. According to previous studies, an electron beam will be generated in the initial stage of pseudospark discharge. This electron beam has the advantages of high energy, high current and self-confinement. It has a promising application in high-power microwave sources, surface treatment of metal materials, etc. To investigate the characteristics of this electron beam, a pseudospark discharge experimental platform is established in this paper. A pseudospark chamber is designed for pseudospark discharge. To trigger the discharge, a high voltage pulse trigger signal is generated by an avalanche transistor Marx circuit and a trigger unit is designed to generate trigger electrons. Faraday Cup is utilized to collect the electron beam and measure the electron waveform. In order to quantitatively characterize the electron beam, we define six electron beam characteristics, including trigger delay, peak current, electron beam charge, electron beam width, electron beam loop current ratio and electron beam loop charge ratio. To investigate the influence of gas pressure and gas type on electron beam characteristics, we experimentally obtained results of electron beam characteristics for different gas pressures and gas type. We mainly investigated the change rule of the electron beam characteristics when the gas pressure changes between 6 Pa and 20 Pa and the similarities and differences of the electron beams under the two gas environments, argon and nitrogen. We find that gas pressure can be used for the modulation of electron beam time delay. The width of the electron beam in the case of nitrogen has a very stable relationship with the gas pressure. Gas pressure and gas type are two important means of controlling the characteristics of pseudospark electron beams.

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Pae, Ki Hong, Chul Min Kim, Vishwa Bandhu Pathak, Chang-Mo Ryu und Chang Hee Nam. „Direct laser acceleration of electrons from a plasma mirror by an intense few-cycle Laguerre–Gaussian laser and its dependence on the carrier-envelope phase“. Plasma Physics and Controlled Fusion 64, Nr. 5 (11.04.2022): 055013. http://dx.doi.org/10.1088/1361-6587/ac5a0a.

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Abstract A direct acceleration scheme to generate high-energy, high-charge electron beams with an intense few-cycle Laguerre–Gaussian (LG) laser pulse was investigated using three-dimensional particle-in-cell simulations. In this scheme, an intense LG laser pulse was irradiated onto a solid density plasma slab. When the laser pulse is reflected, electrons on the target front surface are injected into the longitudinal electric field of the laser and accelerated further. We found that the carrier-envelope phase (CEP) of the few-cycle laser pulse plays a key role in the electron injection and acceleration process. Using a three-cycle LG laser pulse with a 0 = 2 and an appropriate CEP, an about 60 pC electron beam could be obtained at a maximum energy of 16 MeV. In comparison, when a laser pulse with mismatched CEP was used, a total of 4 pC electron beam with a maximum energy of 3.5 MeV was obtained. Linear scaling of electron energy to the laser strength was shown up to a 0 = 100 at which a quasi-monoenergetic electron beam of 850 MeV energy with a charge equal to 600 pC could be obtained. These results demonstrate that high-energy electron beams can be stably generated through direct laser acceleration using a CEP-controlled intense few-cycle LG laser pulse.

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BOULWARE, C. H., J. D. JARVIS, H. L. ANDREWS und C. A. BRAU. „NEEDLE CATHODES FOR HIGH-BRIGHTNESS BEAMS“. International Journal of Modern Physics A 22, Nr. 22 (10.09.2007): 3784–93. http://dx.doi.org/10.1142/s0217751x07037421.

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At the tips of sharp needles, the surface electric field is enhanced by many orders of magnitude. This intensifies thermionic emission and photoemission of electrons through the Schottky effect, and reduces the effect of space charge. The increased current density improves the brightness of electron sources by orders of magnitude. In addition, at very high fields (>109 V/m ), field emission and photo-field emission produce very high current density. Arrays of needles can be used to achieve high total current.

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GLINEC, Y., J. FAURE, A. PUKHOV, S. KISELEV, S. GORDIENKO, B. MERCIER und V. MALKA. „Generation of quasi-monoenergetic electron beams using ultrashort and ultraintense laser pulses“. Laser and Particle Beams 23, Nr. 2 (Juni 2005): 161–66. http://dx.doi.org/10.1017/s0263034605050275.

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Plasma-based accelerators have been proposed for the next generation of compact accelerators because of the huge electric fields they can support. However, it has been difficult to use them efficiently for applications because they produce poor quality particle beams with large energy spreads. Here, we demonstrate a dramatic enhancement in the quality of electron beams produced in laser-plasma interaction: an ultrashort laser pulse drives a plasma bubble which traps and accelerates plasma electrons to a single energy. This produces an extremely collimated and quasi-monoenergetic electron beam with a high charge of 0.5 nanocoulomb at energy 170 ± 20 MeV.

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Panofski, Eva, Ralph Assmann, Florian Burkart, Ulrich Dorda, Luca Genovese, Farzad Jafarinia, Sonja Jaster-Merz et al. „Commissioning Results and Electron Beam Characterization with the S-Band Photoinjector at SINBAD-ARES“. Instruments 5, Nr. 3 (25.08.2021): 28. http://dx.doi.org/10.3390/instruments5030028.

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Over the years, the generation and acceleration of ultra-short, high quality electron beams has attracted more and more interest in accelerator science. Electron bunches with these properties are necessary to operate and test novel diagnostics and advanced high-gradient accelerating schemes, such as plasma accelerators and dielectric laser accelerators. Furthermore, several medical and industrial applications require high-brightness electron beams. The dedicated R&D facility ARES at DESY (Deutsches Elektronen-Synchrotron) will provide such probe beams in the upcoming years. After the setup of the normal-conducting, radio-frequency (RF) photoinjector and linear accelerating structures, ARES successfully started the beam commissioning of the RF gun. This paper gives an overview of the ARES photoinjector setup and summarizes the results of the gun commissioning process. The quality of the first electron beams is characterized in terms of charge, momentum, momentum spread and beam size. Additionally, the dependencies of the beam parameters on RF settings are described. All measurement results of the characterized beams fulfill the requirements for operating the ARES linac with this RF photoinjector.

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ROSENZWEIG, J. B., A. M. COOK, M. DUNNING, R. J. ENGLAND, P. MUSUMECI, M. BELLAVEGLIA, M. BOSCOLO et al. „EXPERIMENTAL TESTING OF DYNAMICALLY OPTIMIZED PHOTOELECTRON BEAMS“. International Journal of Modern Physics A 22, Nr. 23 (20.09.2007): 4158–78. http://dx.doi.org/10.1142/s0217751x0703772x.

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We discuss the design of and initial results from an experiment in space-charge dominated beam dynamics which explores a new regime of high-brightness electron beam generation at the SPARC (located at INFN-LNF, Frascati) photoinjector. The scheme under study employs the natural tendency in intense electron beams to configure themselves to produce a uniform density, giving a nearly ideal beam from the viewpoint of space charge-induced emittance. The experiments are aimed at testing the marriage of this idea with a related concept, emittance compensation, We show that the existing infrastructure at SPARC is nearly ideal for the proposed tests, and that this new regime of operating photoinjector may be the preferred method of obtaining highest brightness beams with lower energy spread. We discuss the design of the experiment, including developing of a novel time-dependent, aerogel-based imaging system. This system has been installed at SPARC, and first evidence for nearly uniformly filled ellipsoidal charge distributions recorded.

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Zhao, Yuan, Haiyang Lu, Cangtao Zhou und Jungao Zhu. „Overcritical electron acceleration and betatron radiation in the bubble-like structure formed by re-injected electrons in a tailored transverse plasma“. Matter and Radiation at Extremes 8, Nr. 1 (01.01.2023): 014403. http://dx.doi.org/10.1063/5.0121558.

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We present a novel scheme for dense electron acceleration driven by the laser irradiation of a near-critical-density plasma. The electron reflux effect in a transversely tailored plasma is particularly enhanced in the area of peak density. We observe a bubble-like distribution of re-injected electrons, which forms a strong quasistatic electromagnetic field that can accelerate electrons longitudinally while also preserving the electron transverse emittance. Simulation results demonstrate that over-dense electrons could be trapped in such an artificial bubble and accelerated to an energy of [Formula: see text]. The obtained relativistic electron beam can reach a total charge of up to 0.26 nC and is well collimated with a small divergence of 17 mrad. Moreover, the wavelength of electron oscillation is noticeably reduced due to the shaking of the bubble structure in the laser field. As a result, the energy of the produced photons is substantially increased to the γ range. This new regime provides a path to generating high-charge electron beams and high-energy γ-ray sources.

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Antonovich, D. A., V. A. Gruzdev, V. G. Zalesski und P. N. Soldatenko. „Plasma source of charged particles for the formation of combined ion-electron beams“. Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 65, Nr. 3 (21.10.2020): 285–91. http://dx.doi.org/10.29235/1561-8358-2020-65-3-285-291.

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One of the ways to increase the efficiency of the implementation of ion-plasma technologies of exposure to the surfaces of various materials is partial or full compensation of the positive charge of ions in the stream or on the treated surface, for which additional emitting systems are used that create compensating electron flows in the discharge space, accelerating gap or on the processed surface. It was previously shown that for the implementation of such a compensating effect, it is possible to use plasma sources of charged particles, capable of forming beams of both signs when the polarity of the accelerating voltage is changed. The main problem in this case is the difficulty in achieving simultaneously high emission efficiency of ions and electrons, since the conditions for their emission from plasma are significantly different. This article proposes a concept and a design developed on its basis for a prototype of a multi-discharge plasma electron-ion source for the joint or alternating formation of electron and ion beams. It is shown that the proposed design realizes the possibility of increasing the perveance by compensating for the space charge by particles of the opposite sign. A number of characteristics of the developed model of a plasma electron-ion source (current-voltage characteristics of the extraction of electrons and ions) are presented and its prospects for further development of an electron-ion source for industrial use on its basis are shown. Combined or alternating ion-electron beams formed in the presented source can be used to implement the technology of applying thin-film layers of metals, semiconductors, and dielectrics to maintain ionization processes and ensure stable discharge burning, compensation of both the space charge in the beam and the surface charge on the formed film.

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Nayak, B., und S. Krishnagopal. „Suppression of beam halo in an RF linac using a hollow electron beam“. Laser and Particle Beams 37, Nr. 01 (März 2019): 38–48. http://dx.doi.org/10.1017/s0263034619000065.

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AbstractHigh-intensity electron linacs have severe space-charge effects that lead to the production of beam halo which degrade the beam quality. For a given charge per bunch, hollow beams have a weaker nonlinear space-charge force. In this paper, we have investigated the possibility of using hollow beam to control halo growth in linacs. We simulate the dynamics of such a beam in a 17 MeV radio frequency linac using ASTRA beam dynamics code and show that it experiences a smaller emittance growth as well as reduced beam halo. The results suggest that using a hollow beam, high charge per bunch could be propagated and accelerated in a radio frequency linac.

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MUELLER, D., L. GRISHAM, I. KAGANOVICH, R. L. WATSON, V. HORVAT, K. E. ZAHARAKIS und Y. PENG. „Multiple electron stripping of heavy ion beams“. Laser and Particle Beams 20, Nr. 4 (Oktober 2002): 551–54. http://dx.doi.org/10.1017/s0263034602204036.

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

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Beaudoin, B. L., J. C. T. Thangaraj, D. Edstrom, J. Ruan, A. H. Lumpkin, D. Broemmelsiek, K. A. Carlson et al. „Longitudinal bunch shaping of picosecond high-charge MeV electron beams“. Physics of Plasmas 23, Nr. 10 (Oktober 2016): 103107. http://dx.doi.org/10.1063/1.4964722.

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Simmons, Robert H., und Johnny S. T. Ng. „A toroidal charge monitor for high-energy picosecond electron beams“. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 575, Nr. 3 (Juni 2007): 334–42. http://dx.doi.org/10.1016/j.nima.2007.03.002.

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KISHEK, R. A., G. BAI, S. BERNAL, D. FELDMAN, T. F. GODLOVE, I. HABER, P. G. O'SHEA et al. „SCALED MODELS: SPACE-CHARGE DOMINATED ELECTRON STORAGE RINGS“. International Journal of Modern Physics A 22, Nr. 22 (10.09.2007): 3838–51. http://dx.doi.org/10.1142/s0217751x07037469.

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New coherent radiation sources in the hard X-ray and Terahertz regimes promise exciting new developments in science, as previously dark areas of the spectrum are brightly illuminated. Ultra-short, ultra-bright radiation packets can probe the structure of matter, and image chemical and biological processes well beyond the present state of the art. Production of this coherent radiation, however, places an unprecedented challenge on the production and acceleration of high-quality electron beams. To deliver a nano-Coulomb of charge with an emittance of less than one micron, while transporting the beam through long sections of acceleration and compression, is the prerequisite for unlocking the gates of this promising new science. Using a low-energy electron storage ring, we deliberately enhance the space charge force while slowing down the time-scale to easily measurable levels so as to maximize our understanding of the particle dynamics necessary for producing bright beams.

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O'SHEA, P. G., R. A. KISHEK, M. REISER, B. BEAUDOIN, S. BERNAL, Y. CUI, A. DIEP et al. „Experiments with space-charge-dominated beams for heavy ion fusion applications“. Laser and Particle Beams 20, Nr. 4 (Oktober 2002): 599–602. http://dx.doi.org/10.1017/s0263034602204218.

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A detailed understanding of the physics of space-charge-dominated beams is vital in the design of heavy ion inertial fusion (HIF) drivers. In that regard, low-energy, high-intensity electron beams provide an excellent model system. The University of Maryland Electron Ring (UMER), currently being installed, has been designed to study the physics of space-charge-dominated beams with extreme intensity in a strong focusing lattice with dispersion. At 10 keV and 100 mA, the beam from the UMER injector has a generalized perveance as much as 0.0015, corresponding to that of proposed HIF drivers. Though compact (11 m in circumference), UMER will be a very complex device by the time of its completion (expected 2003). We present an update on the construction as well as recent experimental results.

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Jiang, Weihua. „A Tutorial on the One-Dimensional Theory of Electron-Beam Space-Charge Effect and Steady-State Virtual Cathode“. Plasma 7, Nr. 1 (05.01.2024): 29–48. http://dx.doi.org/10.3390/plasma7010003.

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The space-charge effects of pulsed high-current electron beams are very important to high-power particle beam accelerators and high-power microwave devices. The related physical phenomena have been studied for decades, and a large number of informative publications can be found in numerous scientific journals over many years. This review article is aimed at systematically summarizing most of the previous findings in a logical manner. Using a normalized one-dimensional mathematical model, analytical solutions have been obtained for the space-charge-limited current of both planar diode and drifting space. In addition, in the case of a beam current higher than the space-charge-limited current, the virtual cathode behavior and beam current reflection are quantitively studied. Furthermore, the criteria of steady-state virtual cathode formation are investigated, which leads to the physical understanding of the unstable nature of the virtual cathode. This review article is expected to serve as an integrated source of related information for young researchers and students working on high-power microwaves and pulsed particle beams.

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Fetterman, A., D. Mihalcea, S. Benson, D. Crawford, D. Edstrom, F. Hannon, P. Piot, J. Ruan und S. Wang. „Photoinjector generation of high-charge magnetized beams for electron-cooling applications“. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1025 (Februar 2022): 166051. http://dx.doi.org/10.1016/j.nima.2021.166051.

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Nassisi, V., und E. Giannico. „Characterization of high charge electron beams induced by excimer laser irradiation“. Review of Scientific Instruments 70, Nr. 8 (August 1999): 3277–81. http://dx.doi.org/10.1063/1.1149904.

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Lumpkin, A. H., R. B. Feldman, B. E. Carlsten, D. W. Feldman, R. L. Sheffield, W. E. Stein, W. J. Johnson, L. E. Thode, S. C. Bender und G. E. Busch. „Initial observations of high-charge, low-emittance electron beams at HIBAF“. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 304, Nr. 1-3 (Juli 1991): 379–85. http://dx.doi.org/10.1016/0168-9002(91)90891-s.

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Fuchs, M., G. Andonian, O. Apsimon, M. Büscher, M. C. Downer, D. Filippetto, A. Lehrach et al. „Plasma-based particle sources“. Journal of Instrumentation 19, Nr. 01 (01.01.2024): T01004. http://dx.doi.org/10.1088/1748-0221/19/01/t01004.

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Abstract High-brightness particle beams generated by advanced accelerator concepts have the potential to become an essential part of future accelerator technology. In particular, high-gradient accelerators can generate and rapidly accelerate particle beams to relativistic energies. The rapid acceleration and strong confining fields can minimize irreversible detrimental effects to the beam brightness that occur at low beam energies, such as emittance growth or pulse elongation caused by space charge forces. Due to the high accelerating gradients, these novel accelerators are also significantly more compact than conventional technology. Advanced accelerators can be extremely variable and are capable of generating particle beams with vastly different properties using the same driver and setup with only modest changes to the interaction parameters. So far, efforts have mainly been focused on the generation of electron beams, but there are concepts to extend the sources to generate spin-polarized electron beams or positron beams. The beam parameters of these particle sources are largely determined by the injection and subsequent acceleration processes. Although, over the last decade there has been significant progress, the sources are still lacking a sufficiently high 6-dimensional (D) phase-space density that includes small transverse emittance, small energy spread and high charge, and operation at high repetition rate. This is required for future particle colliders with a sufficiently high luminosity or for more near-term applications, such as enabling the operation of free-electron lasers (FELs) in the X-ray regime. Major research and development efforts are required to address these limitations in order to realize these approaches for a front-end injector for a future collider or next-generation light sources. In particular, this includes methods to control and manipulate the phase-space and spin degrees-of-freedom of ultrashort plasma-based electron bunches with high accuracy, and methods that increase efficiency and repetition rate. These efforts also include the development of high-resolution diagnostics, such as full 6D phase-space measurements, beam polarimetry and high-fidelity simulation tools. A further increase in beam luminosity can be achieve through emittance damping. Emittance cooling via the emission of synchrotron radiation using current technology requires kilometer-scale damping rings. For future colliders, the damping rings might be replaced by a substantially more compact plasma-based approach. Here, plasma wigglers with significantly stronger magnetic fields are used instead of permanent-magnet based wigglers to achieve similar damping performance but over a two orders of magnitude reduced length.

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Lutz, Kolemann, und Terry Trevino. „High energy laser & systems to neutralise stellar coronal mass ejections (CME) plasma“. Aeronautics and Aerospace Open Access Journal 8, Nr. 1 (16.01.2024): 1–9. http://dx.doi.org/10.15406/aaoaj.2024.08.00187.

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With CME plasma and shockwave travelling at 600+ km/sec, active methods such as high energy electron lasers (HEL) and mirrors are effective at making contact with ionised atoms in CME. Electrons pulsed from kW to MW laser(s) could polarise ionised atoms such as Fe16+, O7/8+, Mg, He2+,etc to fill valence pairs. As high-FIP atoms are electromagnetically trapped with a higher susceptibility from lower e- density and temperatures, CME plasma clouds can be neutralised, separated, and reduced in velocity trajectory around planet. Study outlines interactions between Electron Laser and CME plasma cloud, orbital geometry, build of high energy lasers, subsystems, as well as recoils, and cloud charge dynamics with e- interactions to neutralise CME particles. Additional space-based systems are designed such as mirrors in closer orbit to align lower velocity light beams. In approaching higher electron recombination and FIP ionisation of laser-plasma ion cluster density, max absorption of e- to CME could be approached with similar beam, CME, mirror angles and alignment, where e- couple and fill valence shells. Models evaluate efficacy of coherent laser beams of charged electrons, X-rays, infrared (IR), and/or electron/radio Hz to polarize CME column charge densities, with optimal CME scatter geometry and time window. Low cost ground experiments are discussed. Models suggest every ~1 km gap laser creates when CME t=8.255min creates a 10,067 km gap for Earth to orbit through. Such a HEL laser, reflecting mirrors, and space systems could neutralize plasma CME Cloud within 92.818M mi (Sun-Earth distance) and mitigate effects and trillion dollar costs from Carrington-type CME flares, and supernovae.

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OZUR, G. E., D. I. PROSKUROVSKY, V. P. ROTSHTEIN und A. B. MARKOV. „Production and application of low-energy, high-current electron beams“. Laser and Particle Beams 21, Nr. 2 (April 2003): 157–74. http://dx.doi.org/10.1017/s0263034603212040.

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This article reviews experiments on the production of low-energy, high-current electron beams (LEHCEB) and their use for surface modification of materials. It is shown that electron guns with a plasma anode and an explosive emission cathode are most promising for the production of this type of beams. The problems related to the initiation of explosive emission and the production and transportation of LEHCEBs in plasma-filled diodes are considered. It has been shown that if the rise time of the accelerating voltage is comparable to or shorter than the time it takes for an ion to fly through the space charge layer, the electric field strength at the cathode and the electron current density in the layer are increased. Experimentally, it has been established that the current of the beam transported in the plasma channel is 1–2 orders of magnitude greater than the critical Pierce current and several times greater than the chaotic current of the anode plasma electrons. Methods for improving the uniformity of the energy density distribution over the beam cross section are described. The nonstationary temperature and stress fields formed in metal targets have been calculated. The features of the structure-phase transformations in the surface layers of materials irradiated with LEHCEBs have been considered. It has been demonstrated that in the surface layers quenched from the liquid state, nonequilibrium structure-phase states are formed.

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Sparkes, Ben M., Daniel J. Thompson, Andrew J. McCulloch, Dene Murphy, Rory W. Speirs, Joshua S. J. Torrance und Robert E. Scholten. „High-Coherence Electron and Ion Bunches From Laser-Cooled Atoms“. Microscopy and Microanalysis 20, Nr. 4 (24.04.2014): 1008–14. http://dx.doi.org/10.1017/s1431927614000774.

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AbstractCold atom electron and ion sources produce electron bunches and ion beams by photoionization of laser-cooled atoms. They offer high coherence and the potential for high brightness, with applications including ultra-fast electron-diffractive imaging of dynamic processes at the nanoscale. The effective brightness of electron sources has been limited by nonlinear divergence caused by repulsive interactions between the electrons, known as the Coulomb explosion. It has been shown that electron bunches with ellipsoidal shape and uniform density distribution have linear internal Coulomb fields, such that the Coulomb explosion can be reversed using conventional optics. Our source can create bunches shaped in three dimensions and hence in principle achieve the transverse spatial coherence and brightness needed for picosecond-diffractive imaging with nanometer resolution. Here we present results showing how the shaping capability can be used to measure the spatial coherence properties of the cold electron source. We also investigate space-charge effects with ions and generate electron bunches with durations of a few hundred picoseconds. Future development of the cold atom electron and ion source will increase the bunch charge and charge density, demonstrate reversal of Coulomb explosion, and ultimately, ultra-fast coherent electron-diffractive imaging.

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Ke, Lintong, Changhai Yu, Ke Feng, Zhiyong Qin, Kangnan Jiang, Hao Wang, Shixia Luan et al. „Optimization of Electron Beams Based on Plasma-Density Modulation in a Laser-Driven Wakefield Accelerator“. Applied Sciences 11, Nr. 6 (12.03.2021): 2560. http://dx.doi.org/10.3390/app11062560.

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We demonstrate a simple but efficient way to optimize and improve the properties of laser-wakefield-accelerated electron beams (e beams) based on a controllable shock-induced density down-ramp injection that is achieved with an inserted tunable shock wave. The e beams are tunable from 400 to 800 MeV with charge ranges from 5 to 180 pC. e beams with high reproducibility (of ~95% in consecutive 100 shots) were produced in elaborate experiments with an average root- mean-square energy spread of 0.9% and an average divergence of 0.3 mrad. Three-dimensional particle-in-cell (PIC) simulations were also performed to accordingly verify and uncover the process of the injection and the acceleration. These tunable e beams will facilitate practical applications for advanced accelerator beam sources.

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Romano, Francesco, Giuliana Milluzzo, Fabio Di Di Martino, Maria Cristina D’Oca, Giuseppe Felici, Federica Galante, Alessia Gasparini et al. „First Characterization of Novel Silicon Carbide Detectors with Ultra-High Dose Rate Electron Beams for FLASH Radiotherapy“. Applied Sciences 13, Nr. 5 (25.02.2023): 2986. http://dx.doi.org/10.3390/app13052986.

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Ultra-high dose rate (UHDR) beams for FLASH radiotherapy present significant dosimetric challenges. Although novel approaches for decreasing or correcting ion recombination in ionization chambers are being proposed, applicability of ionimetric dosimetry to UHDR beams is still under investigation. Solid-state sensors have been recently investigated as a valuable alternative for real-time measurements, especially for relative dosimetry and beam monitoring. Among them, Silicon Carbide (SiC) represents a very promising candidate, compromising between the maturity of Silicon and the robustness of diamond. Its features allow for large area sensors and high electric fields, required to avoid ion recombination in UHDR beams. In this study, we present simulations and experimental measurements with the low energy UHDR electron beams accelerated with the ElectronFLASH machine developed by the SIT Sordina company (IT). The response of a newly developed 1 × 1 cm2 SiC sensor in charge as a function of the dose-per-pulse and its radiation hardness up to a total delivered dose of 90 kGy, was investigated during a dedicated experimental campaign, which is, to our knowledge, the first characterization ever done of SiC with UHDR-pulsed beams accelerated by a dedicated ElectronFLASH LINAC. Results are encouraging and show a linear response of the SiC detector up to 2 Gy/pulse and a variation in the charge per pulse measured for a cumulative delivered dose of 90 kGy, within ±0.75%.

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Gazis, Nick, Andrea Bignami, Emmanouil Trachanas, Melina Moniaki, Evangelos Gazis, Dimitrios Bandekas und Nikolaos Vordos. „Simulation Dosimetry Studies for FLASH Radiation Therapy (RT) with Ultra-High Dose Rate (UHDR) Electron Beam“. Quantum Beam Science 8, Nr. 2 (24.05.2024): 13. http://dx.doi.org/10.3390/qubs8020013.

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FLASH-radiotherapy (RT) presents great potential as an alternative to conventional radiotherapy methods in cancer treatment. In this paper, we focus on simulation studies for a linear particle accelerator injector design using the ASTRA code, which permits beam generation and particle tracking through electromagnetic fields. Space charge-dominated beams were selected with the aim of providing an optimized generated beam profile and accelerator lattice with minimized emittance. The main results of the electron beam and ultra-high dose rate (UHDR) simulation dosimetry studies are reported for the FLASH mode radiobiological treatment. Results for the percentage depth dose (PDD) at electron beam energies of 5, 7, 15, 25, 50, 100 MeV and 1.2 GeV for Poly-methyl-methacrylate (PMMA) and water phantom vs. the penetration depth are presented. Additionally, the PDD transverse profile was simulated for the above energies, delivering the beam to the phantom. The simulation dosimetry results provide an UHDR electron beam under the conditions of the FLASH-RT. The performance of the beam inside the phantom and the dose depth depends on the linear accelerator beam’s energy and stability.

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V. Miginky, Sergey. „An Acceptance Optimizer for High-Current Beamlines“. Siberian Journal of Physics 3, Nr. 2 (01.07.2008): 80–87. http://dx.doi.org/10.54362/1818-7919-2008-3-2-80-87.

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A novel approach to the problem of beamlines development for high-current electron beam is put forward. An electron bunch is considered as a set of independently moving uniformly charged emittanceless slices with different currents, energies, and initial conditions. This locally cold beam model is accurate enough for space charge dominated beams if the bunch length in the center-of-mass system is much bigger than its transverse size. The model permits effective numerical maximization of the acceptance of a beamline to a beam, which parameters are known only approximately, and reliable prediction of beam loss. A simulation code implemented this approach is described. Some examples of existing and designed beamlines are presented.

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Hogan, Mark J. „Electron and Positron Beam–Driven Plasma Acceleration“. Reviews of Accelerator Science and Technology 09 (Januar 2016): 63–83. http://dx.doi.org/10.1142/s1793626816300036.

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Particle accelerators are the ultimate microscopes. They produce high energy beams of particles — or, in some cases, generate X-ray laser pulses — to probe the fundamental particles and forces that make up the universe and to explore the building blocks of life. But it takes huge accelerators, like the Large Hadron Collider or the two-mile-long SLAC linac, to generate beams with enough energy and resolving power. If we could achieve the same thing with accelerators just a few meters long, accelerators and particle colliders could be much smaller and cheaper. Since the first theoretical work in the early 1980s, an exciting series of experiments have aimed at accelerating electrons and positrons to high energies in a much shorter distance by having them “surf” on waves of hot, ionized gas like that found in fluorescent light tubes. Electron-beam-driven experiments have measured the integrated and dynamic aspects of plasma focusing, the bright flux of high energy betatron radiation photons, particle beam refraction at the plasma–neutral-gas interface, and the structure and amplitude of the accelerating wakefield. Gradients spanning kT/m to MT/m for focusing and 100[Formula: see text]MeV/m to 50[Formula: see text]GeV/m for acceleration have been excited in meter-long plasmas with densities of 10[Formula: see text]–10[Formula: see text][Formula: see text]cm[Formula: see text], respectively. Positron-beam-driven experiments have evidenced the more complex dynamic and integrated plasma focusing, 100[Formula: see text]MeV/m to 5[Formula: see text]GeV/m acceleration in linear and nonlinear plasma waves, and explored the dynamics of hollow channel plasma structures. Strongly beam-loaded plasma waves have accelerated beams of electrons and positrons with hundreds of pC of charge to over 5[Formula: see text]GeV in meter scale plasmas with high efficiency and narrow energy spread. These “plasma wakefield acceleration” experiments have been mounted by a diverse group of accelerator, laser and plasma researchers from national laboratories and universities around the world. This article reviews the basic principles of plasma wakefield acceleration with electron and positron beams, the current state of understanding, the push for first applications and the long range R&D roadmap toward a high energy collider.

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ROSENZWEIG, J., und O. WILLIAMS. „LIMITS ON PRODUCTION OF NARROW BAND PHOTONS FROM INVERSE COMPTON SCATTERING“. International Journal of Modern Physics A 22, Nr. 23 (20.09.2007): 4333–42. http://dx.doi.org/10.1142/s0217751x07037871.

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In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry.

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Peebles, J. L., G. Fiksel, M. R. Edwards, J. von der Linden, L. Willingale, D. Mastrosimone und Hui Chen. „Magnetically collimated relativistic charge-neutral electron–positron beams from high-power lasers“. Physics of Plasmas 28, Nr. 7 (Juli 2021): 074501. http://dx.doi.org/10.1063/5.0053557.

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Katz, I., G. A. Jongeward, D. E. Parks, David L. Reasoner und Carolyn K. Purvis. „Energy broadening due to space-charge oscillations in high current electron beams“. Geophysical Research Letters 13, Nr. 1 (Januar 1986): 64–67. http://dx.doi.org/10.1029/gl013i001p00064.

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Cavenaile, M., C. R. J. Charles, O. Kester, B. E. Schultz, F. Ames und R. Kanungo. „Pulse-stretching out of the CANREB EBIS“. Journal of Physics: Conference Series 2743, Nr. 1 (01.05.2024): 012077. http://dx.doi.org/10.1088/1742-6596/2743/1/012077.

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Abstract The CANadian Rare isotope facility with Electron-Beam ion source (CANREB) at TRIUMF is set to deliver rare isotope beams in high charge states. In the Electron Beam Ion Source (EBIS) ions are charge-bred by collisions with an electron beam of up to 500 mA. A strong magnetic field (up to 6T) maximizes the overlap between ions and electron beam and increases the breeding efficiency. Ion confinement is maintained by a combination of an electrostatic field and the electron beam space-charge potential. Ions are released by lowering the trapping potential with a step function. The system is operated at a pulse repetition frequency up to 100 Hz. Due to the short trap length, this fast extraction scheme produces pulses shorter than 10 µs with high instantaneous rates that can saturate detectors in experiments. Stretching the pulse can be done using a slowly varying voltage function to modify trap electrode potentials instead of a step function. The ideal function produces a pulse with a flat top distribution and can be calculated by knowing the ion energy distribution inside the trap. The latest pulse-stretching results will be discussed including the latest pulse duration up to 1.4 ms that have been produced. The slow extraction scheme has also been used for a measurement of the effective energy distribution of the ions inside the trap.

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Krainara, Siriwan, Shuya Chatani, Heishun Zen, Toshiteru Kii und Hideaki Ohgaki. „Manipulation of Laser Distribution to Mitigate the Space-Charge Effect for Improving the Performance of a THz Coherent Undulator Radiation Source“. Particles 1, Nr. 1 (07.11.2018): 238–52. http://dx.doi.org/10.3390/particles1010018.

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A THz coherent undulator radiation (THz-CUR) source has been developed at the Institute of Advanced Energy, Kyoto University. A photocathode Radio-Frequency (RF) gun and a bunch compressor chicane are used for generating short-bunch electron beams. When the electron beam energy is low, the space-charge effect strongly degrades the beam quality, such as the bunch length and the energy spread at the high bunch charge condition at around 160 pC, and results in the reduction of the highest frequency and the maximum radiated power of the THz-CUR. To mitigate the space charge effect, we have investigated the dependence of the electron beam quality on the laser distribution in transverse and longitudinal directions by using a numerical simulation code, General Particle Tracer GPT. The manipulation of the laser distribution has potential for improving the performance of the THz-CUR source. The electron bunch was effectively compressed with the chicane magnet when the laser transverse distribution was the truncated Gaussian profile, illuminating a cathode. Moreover, the compressed electron bunch was shortened by enlarging the laser pulse width. Consequently, an enhancement of the radiated power of the THz-CUR has been indicated.

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SEIDL, P. A., D. BACA, F. M. BIENIOSEK, A. FALTENS, S. M. LUND, A. W. MOLVIK, L. R. PROST und W. L. WALDRON. „The high current experiment: First results“. Laser and Particle Beams 20, Nr. 3 (Juli 2002): 435–40. http://dx.doi.org/10.1017/s0263034602203146.

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The High Current Experiment (HCX) is being assembled at Lawrence Berkeley National Laboratory as part of the U.S. program to explore heavy ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge dominated heavy ion beams at high space-charge intensity (line-charge density ∼ 0.2 μC/m) over long pulse durations (>4 μs). This machine will test transport issues at a driver-relevant scale resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and beam steering, matching, image charges, halo, lost-particle induced electron effects, and longitudinal bunch control. We present the first experimental results carried out with the coasting K+ ion beam transported through the first 10 electrostatic transport quadrupoles and associated diagnostics. Later phases of the experiment will include more electrostatic lattice periods to allow more sensitive tests of emittance growth, and also magnetic quadrupoles to explore similar issues in magnetic channels with a full driver scale beam.

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Malka, V., J. Faure, Y. Glinec und A. F. Lifschitz. „Laser–plasma accelerator: status and perspectives“. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, Nr. 1840 (25.01.2006): 601–10. http://dx.doi.org/10.1098/rsta.2005.1725.

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Laser–plasma accelerators deliver high-charge quasi-monoenergetic electron beams with properties of interest for many applications. Their angular divergence, limited to a few mrad, permits one to generate a small γ ray source for dense matter radiography, whereas their duration (few tens of fs) permits studies of major importance in the context of fast chemistry for example. In addition, injecting these electron beams into a longer plasma wave structure will extend their energy to the GeV range. A GeV laser-based accelerator scheme is presented; it consists of the acceleration of this electron beam into relativistic plasma waves driven by a laser. This compact approach (centimetres scale for the plasma, and tens of meters for the whole facility) will allow a miniaturization and cost reduction of future accelerators and derived X-ray free electron laser (XFEL) sources.

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Wang, Jia, Ming Zeng, Xiaoning Wang, Dazhang Li und Jie Gao. „Scissor-cross ionization injection in laser wakefield accelerators“. Plasma Physics and Controlled Fusion 64, Nr. 4 (18.02.2022): 045012. http://dx.doi.org/10.1088/1361-6587/ac4853.

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Abstract We propose to use a frequency-doubled pulse colliding with the driving pulse at an acute angle to trigger ionization injection in a laser wakefield accelerator. This scheme effectively reduces the duration of the injection; thus, high injection quality is obtained. Three-dimensional particle-in-cell simulations show that electron beams with energy of ∼ 500 MeV , a charge of ∼ 40 pC , energy spread of ∼ 1 % and normalized emittance of a few millimeter milliradian can be produced by ∼ 100 TW laser pulses. By adjusting the angle between the two pulses, the intensity of the trigger pulse and the gas doping ratio, the charge and energy spread of the electron beam can be controlled.

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Foster, J. C., J. W. McClory, S. B. Swanekamp, D. D. Hinshelwood, A. S. Richardson, P. E. Adamson, J. W. Schumer, R. W. James, P. F. Ottinger und D. Mosher. „Particle-in-cell simulations of ion dynamics in a pinched-beam diode“. Physics of Plasmas 29, Nr. 5 (Mai 2022): 053103. http://dx.doi.org/10.1063/5.0089904.

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Particle-in-cell simulations of a 1.6 MV, 800 kA, and 50 ns pinched-beam diode have been completed with emphasis placed on the quality of the ion beams produced. Simulations show the formation of multiple regions in the electron beam flow characterized by locally high charge and current density (“hot spots”). As ions flow through the electron-space-charge cloud, these hot spots electrostatically attract ions to produce a non-uniform ion current distribution. The length of the cavity extending beyond the anode-to-cathode gap (i.e., behind the cathode tip) influences both the number and amplitude of hot spots. A longer cavity length increases the number of hot spots yet significantly reduces the amplitude producing a smoother, more uniform ion beam than for shorter cavities. The net current and the ion bending angles are also significantly smaller with long cavities.

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Pozimski, J., R. Dölling, P. Groß und H. Klein. „Determination of electron temperature in partial space-charge-compensated high-perveance ion beams“. Il Nuovo Cimento A 106, Nr. 11 (November 1993): 1713–18. http://dx.doi.org/10.1007/bf02821271.

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Uhlig, Jens, Claes-Göran Wahlström, Monika Walczak, Villy Sundström und Wilfred Fullagar. „Laser generated 300 keV electron beams from water“. Laser and Particle Beams 29, Nr. 4 (Dezember 2011): 415–24. http://dx.doi.org/10.1017/s0263034611000516.

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Abstract300 keV electron beams with energy peaked in the range 280–390 keV were generated by focusing a high contrast ratio but temporally double pulsed 800 nm ultrafast laser onto a flowing water jet under both helium atmosphere at ambient pressure and water aspirator vacuum conditions, using laser intensities in the range 1015–1018 Wcm−2. Their characteristics have been investigated as functions of inter-pulse delay, incidence geometry and laser pulse chirp. Shot-to-shot variation of the beams' equatorial and azimuthal distributions was also recorded in real time. Measurements of the emitted charge and energy have been performed. Secondary X-ray emission arising from impingement of the electron beams on the target chamber walls and other parts of the apparatus have been identified. Preliminary results after transition to a high repetition rate laser system have shown similar behavior. Approaches for improvements and applications are suggested.

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Kim, Jongwon, Hyock-Jun Son und Young-Ho Park. „Design for simultaneous acceleration of stable and unstable beams in a superconducting heavy-ion linear accelerator for RISP“. Modern Physics Letters A 32, Nr. 36 (21.11.2017): 1750203. http://dx.doi.org/10.1142/s0217732317502030.

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The post-accelerator of isotope separation on-line (ISOL) system for rare isotope science project (RISP) is a superconducting linear accelerator (SC-linac) with a DC equivalent voltage of around 160 MV. An isotope beam extracted from the ISOL is in a charge state of [Formula: see text] and its charge state is increased to [Formula: see text] by charge breeding with an electron beam ion source (EBIS). The charge breeding takes tens of ms and the pulse width of extracted beam from the EBIS is tens of [Formula: see text]s, which operates at up to 30 Hz. Consequently a large portion of radio frequency (rf) time of the post SC-linac is unused. The post-linac is equipped also with an electron cyclotron resonance (ECR) ion source for stable ion acceleration. Thanks to the large phase acceptance of SC-linac, it is possible to accelerate simultaneously both stable and radioisotope ions with a similar charge to mass ratio by sharing rf time. This operation scheme is implemented for RISP with the addition of an electric chopper and magnetic kickers. The facility will be capable of providing the users of the ISOL and in-flight fragmentation (IF) systems with different beams simultaneously, which would help nuclear science users in obtaining a beam time as high-precision measurements often need long hours.

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ZIMMERMANN, F., und D. H. WHITTUM. „FINAL-FOCUS SYSTEM AND COLLISION SCHEMES FOR A 5-TeV W-BAND LINEAR COLLIDER“. International Journal of Modern Physics A 13, Nr. 14 (10.06.1998): 2525–49. http://dx.doi.org/10.1142/s0217751x98001311.

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A 3-km long high-gradient W-band switched matrix linac may, in parallel channels, accelerate multiple electron and positron bunches to an energy of 2.5 TeV, with a tight control on the intra-bunch energy spread. In this report, we describe a final-focus system for such an accelerator, whose length is restrained by eliminating chromatic correction. The interaction point (IP) spot size is limited by synchrotron radiation in the last quadrupole (Oide effect). The energy loss due to beamstrahlung is optionally suppressed by combining bunches of opposite charge and colliding the neutral beams. We present two different high-luminosity multiple-collision schemes, which can provide a luminosity of up to 1035 cm -2 s -1, with only about 1 MW average beam power. In the first scheme, batches of equally-charged bunches are combined into superbunches which, possibly after charge compensation, are collided head-on with the opposing beam. In the second scheme, 25 charge-neutral electron-positron bunch pairs of one beam are each collided with 25 neutral bunch pairs of the other beam. These multiplexed collisions are facilitated by a crossing angle and by crab cavities upstream of the electron-positron combiner; however they also require focusing channels (e.g., a crystal) preserving IP beam size between the collision points, a difficult if not impossible construct. We describe the challenges posed by each approach.

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