Assessment of the Structural Vibration Effect on Plasma Current Measurement Using a Fiber Optic Current Sensor in ITER.

In this paper, we assess the effect of cryostat bridge vibrations on the plasma current measurement accuracy when using a fiber optic current sensor (FOCS) in ITER. The impact of vibrations on the light polarization state was first experimentally investigated using a miniaturized mock-up which represented a relevant part of the ITER FOCS structure. The set-up was then numerically simulated using the Jones matrix approach. Equivalent vibration matrices obtained from the experiment were used in the simulations to determine the effect of the vibrations on the FOCS accuracy. It is demonstrated that although the vibrations imply some changes in the polarization state, this effect can be strongly reduced when a proper low-birefringent spun optical fiber is used. The ITER requirement regarding the plasma current measurement accuracy can therefore be fulfilled.

Design and Development of a Diagnostic System for a Non-Intercepting Direct Measure of the SPIDER Ion Source Beamlet Current.

Stable and uniform beams with low divergence are required in particle accelerators; therefore, beyond the accelerated current, measuring the beam current spatial uniformity and stability over time is necessary to assess the beam performance, since these parameters affect the perveance and thus the beam optics. For high-power beams operating with long pulses, it is convenient to directly measure these current parameters with a non-intercepting system due to the heat management requirement. Such a system needs to be capable of operating in a vacuum in the presence of strong electromagnetic fields and overvoltages, due to electrical breakdowns in the accelerator. Finally, the measure of the beam current needs to be efficiently integrated into a pulse file with the other relevant plant parameters to allow the data analyses required for beam optimization. This paper describes the development, design and commissioning of such a non-intercepting system, the so-called beamlet current monitor (BCM), aimed to directly measure the electric current of a particle beam. In particular, the layout of the system was adapted to the SPIDER experiment, the ion source (IS) prototype of the heating neutral beam injectors (HNB) for the ITER fusion reactor. The diagnostic is suitable to provide the electric current of five beamlets from DC up to 10 MHz.

Comparing Entrustment and Competence: An Exploratory Look at Performance-Relevant Information in the Final Year of a Veterinary Program.

Workplace-based assessments and entrustment scales have two primary goals: providing formative information to assist students with future learning; and, determining if and when learners are ready for safe, independent practice. To date, there has not been an evaluation of the relationship between these performance-relevant information pieces in veterinary medicine. This study collected quantitative and qualitative data from a single cohort of final-year students (n = 27) across in-training evaluation reports (ITERs) and entrustment scales in a distributed veterinary hospital environment. Here we compare progression in scoring and performance within and across student, within and across method of assessment, over time. Narrative comments were quantified using the Completed Clinical Evaluation Report Rating (CCERR) instrument to assess quality of written comments. Preliminary evidence suggests that we may be capturing different aspects of performance using these two different methods. Specifically, entrustment scale scores significantly increased over time, while ITER scores did not. Typically, comments on entrustment scale scores were more learner specific, longer, and used more of a coaching voice. Longitudinal evaluation of learner performance is important for learning and demonstration of competence; however, the method of data collection could influence how feedback is structured and how performance is ultimately judged.

The European roadmap towards fusion electricity.

The European roadmap to the realization of fusion electricity breaks the quest into eight missions. For each mission, it reviews the current status of research, identifies open issues, and proposes a research and development programme. ITER is the key facility on the roadmap as it is expected to achieve most of the important milestones on the path to fusion power. The Fusion Roadmap is tightly connected to the ITER schedule and the vast majority of resources in fusion research are presently dedicated to ITER and its accompanying experiments. Parallel to the ITER exploitation in the 2030s, the construction of the demonstration power plant DEMO needs to be prepared. DEMO will for the first time supply fusion electricity to the grid and it will have a self-sufficient fuel cycle. The design, construction and operation of DEMO require full involvement of industry to ensure that, after a successful DEMO operation, industry can take responsibility for commercial fusion power. The European fusion roadmap provides a coherent path towards the fusion power plant, and it proposes in an integrated way to find solutions for all challenges that still need to be addressed. This article is part of a discussion meeting issue 'Fusion energy using tokamaks: can development be accelerated?'

An economical viable tokamak fusion reactor based on the ITER experience.

This is my personal vision and outlook towards a fusion reactor based on my extensive experience from being part of the ITER design, and now construction, as well as leading the largest fusion technology program worldwide (KIT-Karlsruhe Institute of Technology) for 7 years. In particular, I want to discuss how a fusion reactor can be economically viable without employing too advanced physics and technology. It certainly will be a pulsed machine (approx. 20 000 s pulses) with thermal energy storage (turbine is steady state). I also want to discuss the optimum machine size and toroidal field for such a machine and why I think that high field and smaller plasmas may not necessarily make a fusion reactor more competitive. When one extrapolates from today's knowledge on ITER construction, even considering that ITER can be built much cheaper, it is clear that a fusion power plant will cost more than 10 or more likely more than 15 billion Euros/Dollars (the first of a kind even approx. 30 billion). Therefore, in order to have an economically attractive fusion reactor, it needs to produce a large amount of power (on the order of 2.5 GW electric). The possible size (R ∼ 10 m) and reasonably conservative physics basis of such a machine will be briefly described in the presentation. If we are successful in achieving advanced physics in a burning plasma, e.g. in ITER, then we can make the machine slightly smaller but the principal arguments for a large machine will not change significantly. Key technologies and their status will be discussed with particular emphasis on a realistic blanket and divertor design and the size and issues of a tritium-plant (T-plant) for such a machine as well as the challenges which have to be overcome beyond what is needed for ITER. Finally, a simple economic consideration will be discussed to show that a large machine could be economically viable, even in today's environment, in particular, in competition with renewables. This article is part of a discussion meeting issue 'Fusion energy using tokamaks: can development be accelerated?'.

Influence of Hydrogen Plasma on the Surface Structure of Beryllium.

This paper presents the research results of hydrogen plasma effect on the surface structure of the TGP-56 beryllium. In the linear simulator, the operating conditions of the first wall of ITER are simulated. Beryllium was irradiated with hydrogen plasma at surface temperatures of ~360 °C, ~800 °C, and ~1200 °C, depending on its location in the ITER chamber; with a different number of pulses with a duration of each pulse of 500 s. Samples of irradiated beryllium were subjected to a set of material studies. Experimental data were obtained on the change in the structure of the surface and edges of the beryllium samples after the plasma effect. It was found that at normal (2 MW/m2) and increased (4.7 MW/m2) heat fluxes on the first wall of the ITER, the edges and beryllium surface have good resistance to erosion. Under critical conditions close to the melting point, beryllium strongly erodes and evaporates. It has been established that this material has a high resource resistance to hydrogen plasma effect in the ITER under operating conditions.

Recent progress in Chinese fusion research based on superconducting tokamak configuration.

Fusion energy is a promising source of clean energy, which could solve energy shortages and environmental pollution. Research into controlled fusion energy has been ongoing for over half a century. China has created a clear roadmap for magnetic confinement fusion development, where superconducting tokamaks will be used in commercial fusion reactors. The Experimental Advanced Superconducting Tokamak (EAST) is the world's first fully superconducting tokamak with upper and lower divertors, which aims at long-pulse, steady-state, H-mode operation, and 101-s H-mode discharge had been achieved. In 2007, China joined the International Thermonuclear Experimental Reactor (ITER) and became one of its seven members. Thirteen procurement packages are undertaken by China, covering superconducting magnets, power supplies, plasma-facing components (PFCs), diagnostics, etc. To bridge the gap between the ITER and fusion demonstration power plants (DEMOs), China is planning to build the Chinese Fusion Engineering Testing Reactor (CFETR) to demonstrate related technologies and physics models. The engineering design of the CFETR was completed in 2020, and Comprehensive Research Facilities for Fusion Technology (CRAFT) are being constructed to explore the key technologies used in the CFETR.

Investigations on Caesium Dispersion and Molybdenum Coating on SPIDER Components.

SPIDER is the 100 keV full-size Negative Ion Source prototype of the ITER Neutral Beam Injector, operating at Consorzio RFX in Padova, Italy. The largest Negative Ion Source in the world, SPIDER generates an RF driven plasma from which Deuterium or Hydrogen negative ions are produced and extracted. At the end of 2021, a scheduled long-term shutdown started to introduce major modifications and improvements aiming to solve issues and drawbacks identified during the first three years of SPIDER operations. The first action of the shutdown period was the disassembly and characterization of the SPIDER beam source after removal from the vacuum vessel and its placement inside the clean room. Each component was carefully assessed and catalogued, following a documented procedure. Some source components, i.e., the Plasma Grid, Extraction Grid and Bias Plate, revealed the presence of different and non-uniform red, white and green coatings that might be correlated to back-streaming positive ions impinging on grid surfaces, electrical discharges and caesium evaporation. Thus, several analyses have been carried out to understand the nature of such coatings, with the study still ongoing. The evidence of caesium evaporation and deposition on molybdenum-coated SPIDER components, such as the formation of oxides and hydroxides, is demonstrated through surface characterization analyses with the use of the Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS).

Influence of the Carbidized Tungsten Surface on the Processes of Interaction with Helium Plasma.

This paper presents the results of experimental studies of the interaction of helium plasma with a near-surface tungsten carbide layer. The experiments were implemented at the plasma-beam installation. The helium plasma loading conditions were close to those expected in the ITER divertor. The technology of the plasma irradiation was applied in a stationary type linear accelerator. The impact of the helium plasma was realized in the course of the experiment with the temperatures of ~905 °C and ~1750 °C, which were calculated by simulating heat loading on a tungsten monoblock of the ITER divertor under the plasma irradiation at the load of 10 MW/m2 and 20 MW/m2, respectively. The structure was investigated with scanning microscopy, transmitting electron microscopy and X-ray analysis. The data were obtained showing that the surface morphology changed due to the erosion. It was found that the carbidization extremely impacted the plasma-tungsten interaction, as the plasma-tungsten interaction with the carbide layer led to the carbon sputtering and partial diffusion towards to the depth of the sample. According to these results, WC-based tungsten carbide is less protected against fracture by helium than W and W2C. An increase in temperature leads to much more extensive surface damage accompanied by the formation of molten and recrystallized flanges.

Dust Monitors in JET with ITER-like Wall for Diagnosis of Mobilized Particles and Co-Deposited Layers.

Silicon plates were installed above the inner and outer divertor of the JET with the ITER-like wall (ILW) after the second and third ILW campaigns to monitor dust generation and deposition with the aim to determine the morphology and content of individual particles and co-deposits, including deuterium content. Particular interest was in metal-based particles: Be, W, steel, Cu. Ex-situ examination after two ILW campaigns was performed by a set of microscopy and ion beam methods including micro-beam nuclear reaction analysis and particle-induced X-ray emission. Different categories of Be-rich particles were found: co-deposits peeled-off from plasma-facing components (PFC), complex multi-element spherical objects, and solid metal splashes and regular spherical droplets. The fuel content on the two latter categories was at the level of 1 × 1016 at/cm-2 indicating that Be melting and splashing occurred in the very last phase of the second experimental campaign. The splashes adhere firmly to the substrate thus not posing risk of Be dust mobilisation. No tungsten droplets were detected. The only W-containing particles were fragments of tungsten coatings from the divertor tiles.

Materials to Be Used in Future Magnetic Confinement Fusion Reactors: A Review.

This paper presents the roadmap of the main materials to be used for ITER and DEMO class reactors as well as an overview of the most relevant innovations that have been made in recent years. The main idea in the EUROfusion development program for the FW (first wall) is the use of low-activation materials. Thus far, several candidates have been proposed: RAFM and ODS steels, SiC/SiC ceramic composites and vanadium alloys. In turn, the most relevant diagnostic systems and PFMs (plasma-facing materials) will be described, all accompanied by the corresponding justification for the selection of the materials as well as their main characteristics. Finally, an outlook will be provided on future material development activities to be carried out during the next phase of the conceptual design for DEMO, which is highly dependent on the success of the IFMIF-DONES facility, whose design, operation and objectives are also described in this paper.

Longitudinal assessment of competency development at The Ohio State University using the competency-based veterinary education (CBVE) model.

With the development of the American Association of Veterinary Medical Colleges' Competency-Based Veterinary Education (CBVE) model, veterinary schools are reorganizing curricula and assessment guidelines, especially within the clinical rotation training elements. Specifically, programs are utilizing both competencies and entrustable professional activities (EPAs) as opportunities for gathering information about student development within and across clinical rotations. However, what evidence exists that use of the central tenets of the CBVE model (competency framework, milestones and EPAs) improves our assessment practices and captures reliable and valid data to track competency development of students as they progress through their clinical year? Here, we report on validity evidence to support the use of scores from in-training evaluation report forms (ITERs) and workplace-based assessments of EPAs to evaluate competency progression within and across domains described in the CBVE, during the final year clinical training period of The Ohio State University's College of Veterinary Medicine (OSU-CVM) program. The ITER, used at the conclusion of each rotation, was modified to include the CBVE competencies that were assessed by identifying the stage of student development on a series of descriptive milestones (from pre-novice to competent). Workplace based assessments containing entrustment scales were used to assess EPAs from the CBVE model within each clinical rotation. Competency progression and entrustment scores were evaluated on each of the 31 rotations offered and high-stakes decisions regarding student performance were determined by a collective review of all the ITERs and EPAs recorded for each learner across each semester and the entire year. Results from the class of 2021, collected on approximately 190 students from 31 rotations, are reported with more than 55 299 total competency assessments combined with milestone placement and 2799 complete EPAs. Approximately 10% of the class was identified for remediation and received additional coaching support. Data collected longitudinally through the ITER on milestones provides initial validity evidence to support using the scores in higher stakes contexts such as identifying students for remediation and for determining whether students have met the necessary requirements to successfully complete the program. Data collected on entrustment scores did not, however, support such decision making. Implications are discussed.

Beyond Efficacy and Effectiveness: Clinical Efficiency Is Necessary for Dissemination.

Nearly all patients interact with critical gatekeepers-insurance companies or centralized healthcare systems. For mental health dissemination efforts to be successful, these gatekeepers must refer patients to evidence-based care. To make these referral decisions, they require evidence about the amount of resources expended to achieve therapeutic gains. Without this information, a bottleneck to widespread dissemination of evidence-based care will remain. To address this need for information, we introduce a new perspective, clinical efficiency. This approach directly ties resource usage to clinical outcomes. We highlight how cost-effectiveness approaches and other strategies can address clinical efficiency, and we also introduce a related new metric, the incremental time efficiency ratio (ITER). The ITER is particularly useful for quantifying the benefits of low-intensity and concentrated interventions, as well as stepped-care approaches. Given that stakeholders are increasingly requiring information on resource utilization, the ITER is a metric that can be estimated for past and future clinical trials. As a result, the ITER can allow researchers to better communicate desirable aspects of treatment, and an increased focus on clinical efficiency can improve our ability to deliver high-quality treatment to more patients in need.

Fusion breeding for mid-century, sustainable, carbon free power.

Fusion has often been billed as the ultimate 21st century sustainable energy source. However, not only is the pace of the program glacially slow, it seems to recede further and further into the future. One way to speed up the delivery of economical fusion could be to change the objective from pure fusion, that is the use of the 14 MeV fusion neutron's kinetic energy to boil water; to fusion breeding, that is the former, but also making use of the neutrons 'potential energy' to breed ten times its energy in the form of nuclear fuel to be burned in separate reactors. The requirements of a fusion breeder are greatly relaxed from the requirements for a pure fusion reactor. For instance, ITER, the large tokamak being built by an international consortium in France, could well be the basis of an economical fusion breeder, but would have to clear many more scientific and technical hurdles before it could become the basis for a pure fusion reactor; hurdles it may or may not be able to clear. Even if it clears them, ITER is unlikely to evolve into an economical pure fusion power supply this century. A fusion breeder as could be alternate approach to speed the delivery of economical of fusion power.

Energetics and reactivity of small beryllium deuterides.

Enthalpies and free energies of reaction for small neutral and charged beryllium deuterides BeD, BeD2, and BeD3 that have been calculated are reported for a temperature range of 0 K to 1000 K. We discuss probable dissociation channels and possible ways of producing BeD by localizing the relevant transition states and by calculating corresponding rate constants. BeD and BeD+ are found to be the most stable ones among the considered compounds. BeD2 and [Formula: see text] are more likely to decompose into Be0,+ + D2 than into BeD0,+ + D. The metastable BeD3 and [Formula: see text] predominantly decompose into BeD0,+ + D2. In light of our results on the reaction energetics, we can interpret the pathways for production of BeD via BeD2 and BeD3 intermediates observed in molecular dynamics simulations.