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A more detailed understanding of the role of N2 in very low Earth orbit (VLEO) on atomic oxygen (AO)-induced material erosion is necessary for future development of the sub-LEO region. Accordingly, a laser-detonation source capable of capturing two different beams is developed. A dual-pulsed supersonic valve (dual-PSV) system is designed to form two beams in one nozzle configuration. It is demonstrated that the dual-PSV is capable of forming two atomic beams at individual energies with various composition ratios. This system is successfully applied for a ground-based simulation of the world’s first material erosion experiment in a sub-LEO aboard Super Low Altitude Test Satellite (SLATS).

A slow and clean fluorine atom beam source is one of the essential components for the low-collision energy scattering experiment involving fluorine atom. In this work, we describe a simple but effective photolysis fluorine atom beam source based on ultraviolet laser photolysis, the performance of which was demonstrated by high-resolution time-of-flight spectra from the reactive scattering of F+HD. This beam source paved the way for studies of low energy collisions with fluorine atoms.

We report on the electrostatic trapping of neutral SrF molecules. The molecules are captured from a cryogenic buffer-gas beam source into the moving traps of a 4.5 m long traveling-wave Stark decelerator. The SrF molecules in $X^2\Sigma^+(v=0, N=1)$ state are brought to rest as the velocity of the moving traps is gradually reduced from 190 m/s to zero. The molecules are held for up to 50 ms in multiple electric traps of the decelerator. The trapped packets have a volume (FWHM) of 1 mm$^{3}$ and a velocity spread of 5(1) m/s which corresponds to a temperature of $60(20)$ mK. Our result demonstrates a factor 3 increase in the molecular mass that has been Stark-decelerated and trapped. Heavy molecules (mass$>$100 amu) offer a highly increased sensitivity to probe physics beyond the Standard Model. This work significantly extends the species of neutral molecules of which slow beams can be created for collision studies, precision measurement and trapping experiments.

Most if not all tokamak heating scenarios involve multiple ion populations being heated simultaneously. To allow the simulation of various aspects of physics dynamics determining the characteristics of operational scenarios in a flexible way, speedy yet sufficiently accurate models are needed, and they should be connected to each other via a ‘backbone’. Under the umbrella of EUROfusion's Integrated Modelling efforts, such a structure is provided. The present paper focuses on one physics aspect: auxiliary heating. After solving the wave equation or beam source equation, this requires solving a set of coupled Fokker–Planck equations for the various populations involved. The adopted modules – enabling accounting for the Coulomb collisional interaction of several non-Maxwellian (minority, majority and beam) populations – are discussed and a practical example of their use is provided: the JET ‘baseline’ scenario heating a minority of${}^3\textrm {He}$ions in a balanced D$+$T mix heated by D and T neutral beams.

The main purpose of the Divertor Tokamak Test facility (DTT) [1], whose construction is starting in Frascati, Italy, is to study solutions to mitigate the issue of power exhaust in conditions relevant for ITER and DEMO. DTT will be equipped with a significant amount of auxiliary heating power (45 MW) to reach PSEP/R = 15 MW m-1 required to be DEMO-relevant [2]. DDT is characterized by high flexibility for the assembling and testing of divertor components and for the different magnetic configurations to address the integrated physics and technology problems. The current conceptual design of the beamline for the DTT Neutral Beam Heating system is here presented, with a particular focus on the effect on the DTT plasma and on the technical solutions adopted to maximize the RAMI indexes (Reliability, Availability, Maintainability and Inspectability) and minimize complexity and costs. Various design options were considered, and a comprehensive set of simulations was carried out using several physics and engineering codes to drive the choice of the most suitable design options and optimize them, aiming at finding a good compromise among different requirements. This paper describes the design of the main components of the DTT NBI beamline, explaining the motivations for the main design choices.

The voltage holding capability of the MITICA Beam Source at 1 MV is a very challenging issue, which could not be fully addressed so far on the basis of experimental results and of theoretical models available in literature. This paper describes a specific HV test campaign which is planned to be implemented in the MITICA Vacuum Vessel using mock-up electrodes reproducing in detail the geometry of the Beam Source and Accelerator. The test set-up will incorporate all essential features both of the single-gap and of the multi-stage insulation, so as to obtain reliable data on voltage holding at 1 MV before the installation of the real components. This approach is intended to reduce the risk related to the HV insulation at 1 MV and, if necessary, to allow to develop the most effective solutions. The tests will be performed in the MITICA Vessel (already available in the NBTF site) both in vacuum and in low-pressure gas. In the paper, the test strategy and requirements are first introduced. Then the sequence of test configurations is defined. Finally, some design solutions for the electrode realization are described and a preliminary plan together with a list of test equipment is given.

The energetic neutral atom detection instrument IMAP-Lo is part of the scientific payload of the upcoming Interstellar Mapping and Acceleration Probe (IMAP) mission by NASA and is designed to analyse interstellar neutral and heliospheric Energetic Neutral Atom fluxes and their composition for energies from 1000 eV down to 10 eV. IMAP is dedicated to extend our knowledge of the local interstellar medium (LISM) and its interaction with the solar magnetic field and the heliosphere. Most importantly, H, He, O and Ne ENAs will be analysed.Calibration and testing of IMAP-Lo is planned in MEFISTO, a unique laboratory test facility for ion and neutral particle instruments at the University of Bern, which can provide the required neutral atom beams. In MEFISTO we have a microwave-induced plasma ion source for beam energies up to 100 keV/q. The ion beam can be converted to a neutral beam in the energy range 10 eV – 3 keV with a removable ion beam neutralizer with decelerating the ion beam first and subsequent neutralisation via surface reflection. It comes with an estimated beam energy reduction of 15 % and energy-dependent transmission. The neutral beam flux into the test chamber therefore depends on the ion beam energy, intensity and species. To improve the calibration process for ENA space instruments such as IMAP-Lo, it is important to measure the neutral beam flux and energy in the test facility.The Absolute Beam Monitor (ABM) is a novel laboratory device developed for absolute neutral particle flux measurements and energy determination of neutral atom beams. The ABM takes advantage of secondary electron emission during surface scattering of incident neutral atoms off a highly polished tungsten plate. The effective rate of neutrals is inferred from detecting secondary electrons and reflected atoms in two electron multipliers as well as its coincidence signal rate. Time difference of the two signals yields the neutrals energy. To date, the ABM is the only device to measure absolute fluxes of neutral atoms in this energy range.Measurements of the neutral beam source in MEFISTO have been performed for several species using the ABM to determine the relation between the effective neutral atom flux and the primary ion beam current at the charge conversion surface, as well as the neutral beam energy, for ion energies from 1000 eV down to 10 eV.

This topical review gathers the last updates concerning caesium-free negative ion sources presented during the $$63{\mathrm {rd}}$$ Course of the International school of Quantum Electronics of the Ettore Majorana Foundation and European collaborative works related to these lectures. Hence, beyond the frame of this course this topical review addresses both theoretical and experimental work performed during these last few years and complexities represented by the conception of a negative ion source ranging from the creation of negative ions to their neutralization.

Degree of paraxiality (DOP) of an anisotropic hollow multi-Gaussian Schell-model (HMGSM) beam is discussed, and the influence of parameters of the beam source on its DOP is studied. It is shown that the parameters of the beam source, including the anisotropy, boundary characteristic, beam waist width, and beam coherence width, may play an important role in its DOP. Moreover, in order to illustrate the behaviors of DOP, the far-field divergence angle of this beam source has also been investigated.

Aim We sought to improve error detection ability during volume modulated arc therapy (VMAT) by dividing and evaluating the treatment plan. Background VMAT involves moving a beam source delivering radiation to tumor tissue through an arc, which significantly decreases treatment time. Treatment planning for VMAT involves many parameters. Quality assurance before treatment is a major focus of research. Materials and methods We used an established VMAT prostate treatment plan and divided it into 12° × 30° sections. In all the sections, only image data that generated errors in one segment and those that were integrally acquired were evaluated by a gamma analysis. This was done with five different patient plans. Results The integrated image data resulting from errors in each section was 100% (tolerance 0.5 mm/0.5%) in the gamma analysis result in all image data. Division of the treatment plans produced a shift in the mean value of each gamma analysis in the cranial, left, and ventral directions of 94.59%, 98.83%, 96.58%, and the discrimination ability improved. Conclusion The error discrimination ability was improved by dividing and verifying the portal imaging.

A subwavelength transmission imaging system based on Bessel–Gauss beam focusing in the 140 GHz frequency band (λ = 2.14 mm) was constructed for food quality inspection purposes. The system employed a low-cost beam source for imaging via mechanical raster scanning, and the high resolution (0.75 λ) focusing module had an extended depth of focus (12.6 λ) and supported a large scan area (800 × 400 mm2, 30 min scan time). The performance of the proof-of-concept system was nondestructively investigated by using a variety of food products, such as chocolate bars, dried laver, red ginseng, and walnuts.

The in-vessel actively cooled components of the SPIDER Beam Source shall be drained and dried in case of major maintenance to limit as much as possible atmospheric corrosion inside the circuits and components, to prevent water spreading, and to allow the execution of vacuum leak tests of the circuits before re-installation inside the vacuum vessel. These operations are needed after the first phase of experiment exploitation of SPIDER begun in May 2018. Drying system consists of evaporation by mass transport of coolant from dead volumes to the dried nitrogen. The drying system capabilities are set for ranges of gas pressure 2-8 bar(a) and heating temperature (70-110 °C) consistently with design and manufacturing in accordance with the Sound Engineering Practice (low hazard level without CE marking applying the Pressure Equipment Directive). On the other hand, the maximum drying temperature is careful evaluations to avoid risks of damage due to excessive thermal deformations, in particular at joints between dissimilar materials and ceramic breaks. Heating up calculations demonstrate the need to increase the gas inlet pressure up to the maximum allowable value in order to decrease the time required for heating: the estimated time to heat up the Electron Dump decreases from about 10 to 3 minutes by increasing the nitrogen pressure from 2.0 bar(a) to 8.0 bar(a). Drying out calculations show that the evaporation capacity of nitrogen increases with the gas inlet temperature; moreover, higher pressures will reduce the drying out duration from about 11 minutes at 2.0 bar(a) to about 3 minutes at 8.0 bar(a). All the calculated values demonstrate the feasibility of the drying system with parameters to be monitored, in particular the gas humidity at the inlet and at the outlet of the component to be dried. A dedicated procurement was set for the realization of the Drying System as a portable skid.

The objective of this study is to investigate the usability of siderite aggregates mentioned above as a heavy-weight aggregate in the heavy-weight concrete production and their effects on physical properties of the heavy-weight concrete mixture. For this purpose, normal-weight aggregate content was decreased at the rate of 20%, 40%, 60%, 80% and 100% by volume of the concrete mixture prepared and mixtures were prepared by its substitution with siderite aggregate at the same rates. Based on the increase in siderite aggregate in the concrete mixture, a considerable increase in unit weight, compressive strength and tensile strength of concrete was obtained. Plate-shaped concrete specimens obtained from combined normal-weight and heavy-weight aggregates were exposed to radiation with different X-ray source (118 keV, 164 keV) and Co-60 (1250 keV) beam source at Cekmece Nuclear Facility. It is clearly seen that the concrete mixture containing siderite aggregate improved 70% radiation absorption characteristics compared to that of the concrete mixture without siderite aggregate.

11th CIRP Conference on Photonic Technologies, LANE, online, 7 Sep 2020 - 10 Sep 2020; Procedia CIRP 94, 936-941 (2020). doi:10.1016/j.procir.2020.09.094 special issue: "11th CIRP Conference on Photonic Technologies [LANE 2020] / Edited by M. Schmidt, F. Vollertsen, E. Govekar", Published by Elsevier, Amsterdam [u.a.]

DEMO is a first-of-a-kind DEMOnstration Fusion Power Plant [1] and is intended to follow the ITER experimental reactor. The main goal of DEMO will be to demonstrate the possibility to produce electric energy for the grid from the fusion reaction early in the second half of the century. The injection of high energy neutral (1 MeV) particle beams is one of the main tools to heat the plasma up to fusion conditions, control the plasma burn phase and ramp the plasma down. Within the EUROfusion Framework a conceptual design of the Neutral Beam Injector (NBI) for the DEMO fusion reactor is currently being developed. Thereby, Reliability, Availability, Maintainability and Inspectability (RAMI) have to be taken into consideration for the conceptual design of the DEMO NBI, together with the exploitation of the currently available return of experience from the ITER NBIs. A novel design of the beam source for the DEMO NBI [2] has been developed by Consorzio RFX between 2016 and 2018, featuring multiple sub-sources and following a modular design concept, with each sub-source featuring its expansion chamber and radio frequency driver. In view of RAMI analysis, this design approach has been compared to the beam source of the ITER heating and current drive NBI, which features a single expansion chamber with eight RF drivers [3]. This study is based on experience gained during operation of ITER relevant sources. Comparing the failure risk of the two different source concepts due to the considered failure modes has allowed for further design developments aiming at exploiting the advantages of the modular approach while minimizing its drawbacks.

We have designed a highly collimated collinear Rb/Cs atomic beam source device used in vacuum environment, which can be applied to both high-precision comparison measurement based on dual-atom system and dual clock. The developed device allows the separate heating of Rb and Cs atoms, and making the operation mode (Rb mode and/or Cs mode) selectable. During operation, Rb and/or Cs atoms are ejected from the same collimating channel, implying that the travelling paths of the two atomic beams overlap precisely. This is very useful and particularly important for dual-atom system, since the environment of the same temperature field and static magnetic field are achieved while the two atoms interact with microwaves. We will discuss the specific application in dual Rb/Cs beam clocks and demonstrate how the dual beam source works in our dual clock.

SPIDER is a 100 kV negative hydrogen/deuterium ion beam source, under operation at Consorzio RFX, which will be exploited for assessment and optimization of the radio frequency source that will be employed in the ITER Neutral Beam Injectors. The in-vessel actively cooled components shall be drained in case of major maintenance to limit as much as possible atmospheric corrosion inside the circuits and components, to prevent water spreading, and finally to allow the execution of vacuum leak tests of the circuits before re-installation of the Beam Source inside the Vacuum Vessel. Draining of hydraulic circuits is first foreseen by gravity after opening of the end connections of hydraulic circuits and then by blowing-out with inert gas. Injection of pressurized nitrogen is simulated by means of one-dimensional models to perform transient two-phase analyses of the blowing-out process with identification of flow regimes. Moreover, three-dimensional transient two-phase analyses are used to deeply investigate the behaviour of components made of complex geometries. Parametric simulations as function of the inlet pressure are carried out to characterize the blowing-out process in terms of flow rate, evacuation time and draining efficiency. The gas and water flow rates are evaluated recognising Rayleigh-Taylor instabilities which occur when the light nitrogen is pushing the heavy water. The maximum allowable pressure for blowing out, in accordance with the Pressure Equipment Directive (PED), is fixed to 1.1 MPa in order to stay in the Sound Engineering Practice category (low hazard level without CE marking). Among all the applied draining pressures, the range between 0.15-0.4 MPa is considered to perform the blowing out process in order to limit the gas speed and take into account possible pressure fluctuations. The analyses were fundamental to design a blowing-out system capable of satisfying the requirements of the different components belonging to the SPIDER Beam Source.

The future prospects of photonuclear reactions studies at the new Extreme Light Infrastructure—Nuclear Physics (ELI-NP) facility are discussed in view of the pursuit of investigating the electromagnetic response of nuclei using γ-ray beams of unprecedented energy resolution and intensity characteristics. We present here the features of the γ-ray beam source, the emerging ELI-NP experimental program involving photonuclear reactions cross section measurements and spectroscopy and angular measurements of γ-rays and neutrons along with the detection arrays currently under implementation.

We established a mathematical method to precisely calculate the radiographic anteversion (RA) and radiographic inclination (RI) angles of the acetabular cup based on anterior-posterior (AP) pelvic radiographs after total hip arthroplasty. Using Mathematica software, a mathematical model for an oblique cone was established to simulate how AP pelvic radiographs are obtained and to address the relationship between the two-dimensional and three-dimensional geometry of the opening circle of the cup. In this model, the vertex was the X-ray beam source, and the generatrix was the ellipse in radiographs projected from the opening circle of the acetabular cup. Using this model, we established a series of mathematical formulas to reveal the differences between the true RA and RI cup angles and the measurements results achieved using traditional methods and AP pelvic radiographs and to precisely calculate the RA and RI cup angles based on post-operative AP pelvic radiographs. Statistical analysis indicated that traditional methods should be used with caution if traditional measurements methods are used to calculate the RA and RI cup angles with AP pelvic radiograph. The entire calculation process could be performed by an orthopedic surgeon with mathematical knowledge of basic matrix and vector equations.

The heating neutral beam (HNB) systems at ITER are designed to inject a total of 33 MW of either 1 MeV D0 or 870 keV H0 beams into the ITER plasma using two injectors with a possible addition of a third injector later to increase the injected power to ∼50 MW. The injectors become radioactive due to the neutron flux from ITER and, in order to avoid the resulting complex remote maintenance, the design, choice of materials and the manufacturing process of each component of the injector is, wherever possible, such that they survive the life time of ITER. To ensure a smooth operational phase of neutral beams at ITER a neutral beam test facility (NBTF) is under construction at Consorzio RFX, Padova, (hereinafter referred to as RFX), which consists of 2 test beds, the 100 kV “SPIDER”, and a 1 MV “MITICA” facilities, which will be used to optimize the source operation for H and D beams. MITICA is essentially a full scale ITER prototype injector for the ITER beam parameters. The manufacturing and operation of the facility will allow validation of the operational space of the injectors and provide valuable information about the manufacturing processes applicable to HNB components. Operation of the two facilities is expected to begin in 2016 and 2019 respectively. Currently experiments on the ELISE facility with a half ITER sized RF beam source are underway. ITER relevant parameters for the H beams have almost been achieved. Efforts are underway to optimise the same with D beams. The experimental database from ELISE will be an important input for establishing the ITER relevant parameter space on the SPIDER source. This paper discusses the present status of the design and development of the injectors for ITER and the progress on the test facilities.

Ar plasma in a fast atom beam (FAB) source with magnetic fields, which was previously developed [Precis. Eng. 62, 106 (2020)] to achieve high-performance surface activated bonding, was analyzed by particle-in-cell-Monte Carlo collision simulation and experimental measurements. Simulation in the proposed FAB source with magnetic fields shows that higher electron density accumulation occurs near the irradiation port by E × B drift, and the potential gradient near the irradiation port steepens, which results in an increase in Ar+ flux to the irradiation port. The variation in the plasma distribution due to the effect of the magnetic field contributes to an increase in the amount of Ar-FAB irradiation, which reduces erosion of the carbon electrodes and suppresses the formation of carbon agglomerates. These simulation results were verified experimentally with Langmuir probe measurements and FAB irradiation experiments with oxide layer removal. The analysis results explain why high performance is achieved with the proposed FAB source.

We generated a pulsed helium droplet beam with average droplet diameters of up to 2 μ m using a solenoid pulsed valve operated at temperatures as low as 7 K. The droplet diameter was controllable over two orders of magnitude, or six orders of the number of atoms per droplet, by lowering the valve temperature from 21 to 7 K. A sudden droplet size change attributed to the so-called “supercritical expansion” was firstly observed in pulsed mode, which is necessary to obtain the micrometer-scale droplets. This beam source is beneficial for experiments that require extremely large helium droplets in intense, pulsed form.

SPIDER experiment is operating at the PRIMA site in Padova (I) since June 2018, with the aim of testing and optimizing the negative ion source prototype for ITER Heating Neutral Beam Injectors. In the first operational phase it was discovered that, as the in-vessel hydrogen pressure exceeds the design requirements, discharges occur on the back of the radio frequency source. A specific operational campaign allowed defining a threshold below which the discharge probability is strongly reduced. In order to extend the operational range of the source pressure above the nominal value, while a significant upgrade of the vacuum pumping system is designed and realized, it was decided to proceed with the SPIDER operations by applying a temporary solution. A mask was installed on the beam source plasma grid, closing most of its apertures, in order to reduce the gas conductance between the inside of the radio frequency source and the surrounding volume. At first only 80 over 1280 apertures are left open, with a specific layout properly arranged so as to guarantee the possibility to diagnose the beam characteristics and to evaluate its uniformity. In the paper the plasma grid masking system will be described in detail, together with the main design choices, the thermal and structural analyses and the tests that were carried out to get a validation of the whole system design. Finally, an overview of the behavior of plasma grid mask during SPIDER operations will be given.

We introduced a new kind of partially coherent beam source which can produce the far field with ring-shaped hollow array profile, and the distribution characteristics of the far-zone spectral density generated by such beam source are investigated in detail. It is shown that the characteristics of the far-zone spectral density, including the size of the hollow of the each lobe, the distance of the adjacent lobes, the orientation of the each lobe, and the number of the lobes, can be effectively manipulated by adjusting the corresponding parameters of the beam source.

Journal of materials processing technology 278, 116514 (2020). doi:10.1016/j.jmatprotec.2019.116514, Published by Elsevier, Amsterdam [u.a.]