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A repetitive pulsed power supply prototype has been designed and implemented for the RCS beam extraction kicker in the CSNS upgrade. The pulsed power supply features an ultra-low impedance Blumlein PFN to generate a fast front and high-current pulse, and a saturable magnetic switch to sharpen the pulse's rising edge at the nanosecond time scale. A detailed report is provided on the practical engineering issues arising from the ultra-low impedance Blumlein PFN in the paper. Additionally, we have utilized simulation and experimental methods to evaluate the effectiveness of the saturation magnetic switch in sharpening the excitation current at the nanosecond time scale. The developed pulsed power supply is capable of generating a pulse current of 6660 A with a rise time of 248 ns, a pulse flat-top duration of 628 ns, a time jitter of ±4.5 ns, and a flat-top ripple of ≤±1 % at a repetition rate of 25 Hz. The design and experimental results of this pulsed power supply are presented in detail in this paper. [ABSTRACT FROM AUTHOR]

Fibre-reinforced polymer (FRP) rebar and geopolymer concrete (GPC) are relatively new construction materials that are now been increasingly used in the construction sectors. Both materials exhibit superior structural and durability properties that also make them a sustainable alternative solution. Due to the absence of any design standard for an FRP-reinforced GPC beam, it is important to validate the efficacy of available standards and literature related to other materials, e.g., FRP-reinforced conventional concrete or GPC alone. Four theories/design standards are considered for this comparison—ACI440.1R-15, CAN/CSA S806-12, parabolic stress block theory, and equivalent rectangular stress block theory for GPC under compression. The accuracy of these four approaches is also examined by studying the flexural performance of both the glass FRP (GFRP) and carbon FRP (CFRP). The FRP-reinforced beams are designed against the actual load they will be subjected to in a real-world scenario. It is concluded that parabolic stress block theory over-estimates the capacity, whereas CSA S806-12 yields the most accurate and conservative results. In addition, the flexural performance of the FRP-reinforced beams is evaluated in terms of ultimate, cracking, and service moment capacity, along with serviceable, ultimate, and residual deflection. [ABSTRACT FROM AUTHOR]

A negative carbon-ion source was designed for accelerator mass spectrometry for application in the medical field to minimize cross-contamination and to increase the measurement efficiency. The ion source was designed by adjusting the distance between the plasma and the extraction electrodes and by changing the anode structure. Various prototype ion source configurations were fabricated to construct an ion source test stand to confirm the carbon beam extraction. The transport efficiency of the negative carbon beam was experimentally investigated using a filament-driven ion source to determine the geometrical effect of the anode configuration. The carbon-ion source was operated under carbon dioxide gas flowing at 3.0 sccm at a high voltage of −30.0 kV and an applied arc current of up to 0.5 A and various magnetic fields. The optimized anode structure and operating conditions of the ion source with the beam characteristics must be verified to measure the beam current with various ion source parameters. The effects of various operating and structural conditions on the beam current are evaluated in this article. [ABSTRACT FROM AUTHOR]

Abstract The recent test of a prototype of beam debuncher device for Electron Beam Ion Source (EBIS), designed within the EMILIE (Enhanced Multi-Ionization of short-Lived Ions for EURISOL) project, is presented in this paper. For a singly ionized Li + 1 ion, high efficiency trapping times up to 1 s were established and a uniform ion extraction with intensity variation of less than 30% was achieved. The test gives promising results regarding the future introduction of debuncher devices to EBIS facilities. Highlights • The ion beam debuncher prototype performances were tested. • Uniform beam extraction with less than 30% intensity variation. • The trapping times with no losses up to 1 s were achieved. • Fully continuous beam extraction demonstrated, even during the ions injection. [ABSTRACT FROM AUTHOR]

Abstract Heavy ion medical machine (HIMM) is the first Chinese heavy ion accelerator facility developed for cancer therapy. After commissioning, the slow extraction efficiency reached nearly 90% for all energies from 120 to 400 MeV/u. The spill duty factor exceeded 90% at a sample rate of 10 kHz. This paper reports the results of the HIMM's slow extraction commissioning. [ABSTRACT FROM AUTHOR]

Abstract A Focal Plane Array FTIR microscope has successfully been coupled to the IRM beamline at the Australian Synchrotron, following the method pioneered at previous beamlines at the SRC and NSLS I synchrotrons, whereby a wide aperture of synchrotron light is split into multiple beams and spatially reconfigured to match the entrance aperture of the FTIR instrumentation. Imaging performance has been assessed using a selection of polymer and biological samples, providing diffraction-limited sub-cellular lateral resolution in the biological materials. We have demonstrated that improved collection times at high lateral resolution are possible, when compared with single element point-mapping microspectroscopy, though this is achieved with a trade off in spectral noise. Future improvements in the use of an FPA detector at the Australian Synchrotron are proposed, including removal of coherent interference and installation of a dedicated beam extraction port for FPA microspectroscopy. [ABSTRACT FROM AUTHOR]

A compact ion microbeam system, which comprises a three-stage acceleration lens and a duoplasmatron-type ion source and produces beam of several hundred kiloelectron-volts, has been developed to form a beam that has a diameter of several micrometers. Previous studies have indicated that a small divergence angle of an incident beam is required to improve the demagnification of the three-stage acceleration lens. A simulation of an ion beam extraction demonstrated that the optimum distance between the anode and the extraction electrode in the ion source could lead to an ion beam being generated with the smallest possible divergence angle. As a result, a hydrogen beam with a 2.6 μm diameter was experimentally produced at 120 keV. [ABSTRACT FROM AUTHOR]

Phenomenon of the deflection of charged particle beam due to channeling in a bent crystal is good investigated and successfully applied for extraction of the beam in high-energy accelerators, at the energies of about 10 GeV and higher. However, a significant practical interest presents the problem of deflection and extraction of charged particles with energies below 1 GeV, for example, production of ultrastable beams of low emittance for medical and biological applications. That’s why two novel crystal techniques, namely: thin sequential straight crystal targets, and array of short bent crystal strips were investigated in this report as elements for extraction of the beam from U-70 accelerator. Experimental results were obtained for extraction of 1.3 GeV protons. [ABSTRACT FROM AUTHOR]

A method is explored to increase the current available for beam extraction by way of increasing bulk plasma ion directed drift velocity in the direction of the ion optics. The enhanced ion drift velocity is achieved by spatially modifying the plasma potential through biasing the individual magnet rings in a four ring, magnetic cusp ion thruster. Actual plasma potential changes were tracked using an emissive probe. The modification of the ion drift velocity is observed using Mach probes. The accompanying increase in ion current at the grid was also observed. A retarding potential analyzer located just downstream of the extraction optics was used to observe the shift in energy of exiting ions. Plasma potential shifts up to 5V were observed. Simulated beam current rose 15% and 20% for xenon and argon, respectively. [ABSTRACT FROM AUTHOR]

The new beam extraction synchronization control system called “Magnetic Cogging” was developed at the Fermilab Booster and it replaces a system called “RF Cogging” as part of the Proton Improvement Plan (PIP). [1] The flux throughput goal for the PIP is 2.2×10 17 protons per hour, which is double the present flux. The flux increase will be accomplished by doubling the number of beam cycles which, in turn, will double the beam loss in the Booster accelerator if nothing else is done. The Booster accelerates beam from 400 MeV to 8 GeV and extracts it to the Main Injector (MI) or Recycler Ring (RR). Cogging controls the beam extraction gap position which is created early in the Booster cycle and synchronizes the gap to the rising edge of the Booster extraction kicker and the MI/RR injection kicker. The RF Cogging system controls the gap position by changing only the radial position of the beam thus limiting the beam aperture and creating beam loss due to beam scraping. The Magnetic Cogging system controls the gap position with the magnetic field of the dipole correctors while the radial position feedback keeps the beam on a central orbit. Also with Magnetic Cogging the gap creation can occur earlier in the Booster cycle when the removed particles are at a lower energy. Thus Magnetic Cogging reduces the deposited energy of the lost particles (beam energy loss) and results in less beam loss activation. Energy loss was reduced by 40% by moving the gap creation energy from 700 MeV to 400 MeV when the Booster Cogging system was switched from RF Cogging to Magnetic Cogging in March 2015. [ABSTRACT FROM AUTHOR]

Various planar channeling experiments, performed at the Mainz Microtron MAMI with electrons at silicon single crystals, have been reanalyzed. Two types of signals have been employed. The low energy loss signal originates from emission of channeling radiation in the energy domain between 0.4 and 9 MeV while the high energy loss signal from electrons which have lost about 50% of their primary energy by emission of bremsstrahlung photons. The (1 1 0) planar channeling data, taken at a beam energy of 855 MeV with the former signal, can well be described on the basis of the solution of the classical Fokker–Planck equation. The measurements with the latter signal at beam energies between 195 and 855 MeV indicate quantum state phenomena. For (1 1 1) planar channeling calculations with the Fokker–Planck equation have also been performed at a beam energy of 6.3 GeV. The results indicate that data taken with a crystal of 60 μm thickness [U. Wienands et al., Phys. Rev. Lett. 114, 074801 (2015)] are probably not suited to determine the predicted “asymptotic” dechanneling length of 265 μm which applies for about 48% of all electrons. [ABSTRACT FROM AUTHOR]

We describe a technique for attaining extended transversally-flat paraxial dose fields with the intermediateenergy carbon beam slowly extracted at the magnetic-field flat-bottom from the IHEP U-70 synchrotron. To this end, a fixed-radius circular beam sweep with the aid of a compact electromechanical wobbler with rotating permanent dipole magnets is applied. A technique for tuning the beam transfer line and the irradiation facility proper at the interim radiobiological workbench with an external fixed target is substantiated. A brief description of its engineering implementation is presented. Results of the successful experimental verification of the technique in question with a carbon nuclear beam from the U-70 machine are reported, in particular, results of the primary radiobiological exercises accomplished in cooperation with the scientists at the MRRC of the Russian Ministry of Healthcare. [ABSTRACT FROM AUTHOR]

Abstract: A kicker system plays an important role in beam extraction and injection for a ring-like accelerator. The kicker system in the Heavy Ion Research Facility in Lanzhou (HIRFL) is used for beam extraction and injection between two cooling storage rings (CSRs). The system consists of two parts: one part is used for beam extraction from the CSR/main (CSRm), and the other is used for beam injection into the CSR/experimental (CSRe). To meet the requirements of special physics experiments, we upgraded the kicker control system. In this upgraded system, the position of the beam bunches can be determined by measuring the phase of the radio frequency (RF) signal in real time because each beam bunch is synchronized with the RF signal. The digital timing control and delay regulatory function, which are based on a new design using ARM+DSP+FPGA technology, achieved a precision of 2.5ns, which is a significant improvement over old system's precision of 5ns. In addition, this system exhibits a better anti-interference capability. Moreover, the efficiency of beam extraction can be enhanced, and the accuracy of the reference voltage setting can reach as low as 0.1%, compared to 2% for the old system. [Copyright &y& Elsevier]

We perform an optimization of pinhole neutron guide systems under systematically varying conditions. It is investigated how neutron guide systems consisting of a parabolic feeder inside the biological shielding followed by a pinhole and an elliptical guide perform with different pinhole sizes and divergence requirements. We have clarified in which situations such a guide system is a viable choice and when the parabolic feeder is necessary in terms of neutron transport. The advantage of this design is the reduction of background from fast thermal neutrons compared to a system without a pinhole, hence the smallest possible pinhole is of interest. It is found that instruments with divergence requirements of ±1.0° will have excellent neutron transport with a 3×3cm2 pinhole, while lower divergence requirements of ±0.5° can do with a smaller pinhole of 2×2cm2. The feeder effectively reduces the necessary pinhole size, and is especially beneficial for short instruments. In addition to these qualities, a feeder will often smoothen the divergence profile, mostly for longer instruments. [ABSTRACT FROM AUTHOR]

Abstract: The new test facility ELISE (Extraction from a Large Ion Source Experiment) has been designed and installed since November 2009 at IPP Garching to support the development of the radio frequency driven negative ion source for the Neutral Beam System on ITER. The test facility is now completely assembled; all auxiliary systems have been commissioned and are operational. First plasma and beam operation is starting in October 2012. The source is designed to deliver an ion beam of 20A of D− ions, operating at 0.3Pa source pressure at an electron to ion current ratio below 1. Beam extraction is limited to 60kV for 10s every 3minutes, while plasma operation of the source can be performed continuously for 1hour. The ion source and extraction system have the same width as the ITER source, but only half the height, i.e. 1×1 m2 source area with an extraction area of 0.1 m2. The aperture pattern of the extraction system and the multi driver source concept stay as close as possible to the ITER design. Easy access to the source for diagnostic tools or modifications allows to analyze and optimize the source performance. Among other possibilities many different magnetic filter field configurations inside the source can be realized to enhance the negative ion extraction and to reduce the co-extraction of electrons. Beam power and profiles are measured by calorimetry and thermography on an inertially cooled target as well as by beam emission spectroscopy. Cs evaporation into the source is done via two dispenser ovens. [Copyright &y& Elsevier]

The ion sources play an important role in the framework of the nuclear fusion, as a fundamental part of the neutral beam injection systems needed for the auxiliary heating of the plasma magnetically confined in fusion devices. In the case of large experiments, such as ITER and beyond, the use of negative ions was found necessary to increase the neutralization efficiency of high-energy beams, calling for an additional effort in the research on the physical mechanisms regulating their formation and extraction as a beam from the source. This paper summarizes the analyses investigating the physical phenomena occurring in the source and their effect on the optics of the extracted beam. The results, carried out by means of advanced numerical tools, are particularly useful to yield a better evaluation of the real performances of the system, and particularly of the accelerator, whose modeling usually neglect some characteristics of the source. These analyses were performed for the specific case of the SPIDER experiment (Source for Production of Ion of Deuterium Extracted from an RF plasma), representing the major test bed for negative ion source worldwide. The choice of a specific device for the source modeling was found useful to support its operational phase and to help the experimental data interpretation and the identification of dangerous operating conditions. Nonetheless, the validity of the results here presented still holds in more general cases. [ABSTRACT FROM PUBLISHER]

The magnetic septa have been developed for the slow beam extraction from the 50 GeV Proton Synchrotron to the Hadron Experimental Hall at J-PARC (Japan Proton Accelerator Research Complex). The magnetic septa consist of two thin magnetic septa, four medium thick magnetic septa and four thick magnetic septa. The typical operating current is 3000 A and the total kick angle is 77 mrad with the 30 GeV proton beam. All parts of the thin and of the medium thick septum magnets are made of inorganic materials to resist high radiation environment. The positions of the thin and medium thick septa can be aligned remotely in the horizontal range of ±5 mm, which enables us to minimize the beam loss at the magnetic septum section. The septa were installed in the synchrotron ring in December, 2008, after a test at KEK (High Energy Accelerator Research Organization), and were successfully operated in the beam time for the slow beam extraction in January and February, 2009, which resulted in the first 30 GeV slow extracted beam delivery to the Hadron Experimental Hall. [ABSTRACT FROM AUTHOR]

The Low Energy Ion Ring (LEIR) is part of the LHC injector chain for ions. The LEIR extraction will use a pulsed magnetic septum, clamped around a metallic vacuum chamber which plays an important role in separating the high vacuum in the LEIR ring (dynamic pressure ∼ 10-12 mbar) from that in the transfer line to the PS, where the vacuum requirements are less stringent. The major technical challenges and novel solutions related to the design of this magnet will be presented. [ABSTRACT FROM AUTHOR]

The spallation neutron source (SNS) is a next generation high-intensity beam facility. The extraction kicker system is a high peak power, high average power, high-precision pulse-wave- form, low beam impedance, and high repetition rate pulsed power system. It has been successfully designed and developed at Brookhaven National Laboratory, Upton, NY. The system consists of fourteen extraction magnet sections inside the ring vacuum chamber and fourteen identical high-voltage modulators located in the service building. The design features a Blumlein pulse-forming-network (PFN) based topology, a low beam impedance termination, a fast current switching thyratron, and low inductance capacitor banks. It has a maximum charging voltage of 50 kV, an open circuit output of 100 kV, and a designed maximum pulsed current output of 4 kA per modulator. The overall system output will reach multiple GW peak power with a 60 pulse/s repetition rate. A prototype modulator has been successfully built and tested well above the SNS requirement. The first batch of production modulators have passed all required tests at manufacture facility and delivered to Oak Ridge National Laboratory, Oak Ridge, TN, and the rest of the production units are under construction. The technical challenges and development results are presented in this paper. [ABSTRACT FROM AUTHOR]

Cherenkov radiation is induced when charged particles travel through dielectric media (such as biological tissue) faster than the speed of light through that medium. Detection of this radiation or excited luminescence during megavoltage external beam radiotherapy (EBRT) can allow emergence of a new approach to superficial dose estimation, functional imaging, and quality assurance for radiation therapy dosimetry. In this letter, the first in vivo Cherenkov images of a real-time Cherenkoscopy during EBRT are presented. The imaging system consisted of a time-gated intensified charge coupled device (ICCD) coupled with a commercial lens. The ICCD was synchronized to the linear accelerator to detect Cherenkov photons only during the 3.25-µs radiation bursts. Images of a tissue phantom under irradiation show that the intensity of Cherenkov emission is directly proportional to radiation dose, and images can be acquired at 4.7 frames/s with SNR 30. Cherenkoscopy > was obtained from the superficial regions of a canine oral tumor during planned, Institutional Animal Care and Use Committee approved, conventional (therapeutically appropriate) EBRT irradiation. Coregistration between photography and Cherenkoscopy validated that Cherenkov photons were detected from the planned treatment region. Real-time images correctly monitored the beam field changes corresponding to the planned dynamic wedge movement, with accurate extent of overall beam field, and expected cold and hot regions. [ABSTRACT FROM AUTHOR]

Beam steering is often encountered in laser diagnostic measurements, especially in flame environments, due to changes in refractive index caused by thermal and species gradients. It can negatively affect the accuracy of the results. In this work, the effects of beam steering on laser-induced incandescence (LII) measurements of pre-vaporized-liquid counterflow flames are assessed. The focus on counterflow flames is to facilitate future detailed experimental campaigns on one-dimensional nonpremixed sooty flames. It is found that the temperature and species gradients in the counterflow configuration have a much more significant impact on the beam profile than in laminar flat flames, especially for heavier fuels. As a result of the changes in the beam profile, for the same applied laser energy, the local fluence shifts markedly with fuel type, therefore, having a direct impact on the LII measurements. A procedure is developed for ensuring accurate measurements and it is shown that, for a specific fuel, it is possible to tailor the laser energy, such that the collected LII signal in the counterflow flames is nearly independent of beam-steering effects. [ABSTRACT FROM AUTHOR]

Beam steering in implant defined coherently coupled vertical cavity surface emitting laser (VCSEL) arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences among elements, inter-element spacing, element size and emitted wavelength is analyzed detailedly and systematically. We design and fabricate 1×2 implant defined VCSEL arrays for optimum beam steering performance. Electronically controlled beam steering with a maximum deflection angle of 1.6° is successfully achieved in the 1×2 VCSEL arrays. The percentage of the power in the central lobe is above 39% when steering. The results show that the steering is controllable. Compared with other beam steering methods, the fabrication process is simple and of low cost. [ABSTRACT FROM AUTHOR]