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In fusion devices, the X-ray plasma emissivity contains essential information on the magnetohydrodynamic activity, the magnetic equilibrium and on the transport of impurities, in particular for tokamaks in the soft X-ray (SXR) energy range of 0.1–20 keV. In this context, tomography diagnostics are a key method to estimate the local plasma emissivity from a given set of line-integrated measurements. Unfortunately, the reconstruction problem is mathematically ill-posed, due to very sparse and noisy measurements, requiring an adequate regularization procedure. The goal of this paper is to introduce, with a didactic approach, some methodology and tools to develop an X-ray tomography algorithm. Based on a simple 1D tomography problem, the Tikhonov regularization is described in detail with a study of the optimal reconstruction parameters, such as the choice of the emissivity spatial resolution and the regularization parameter. A methodology is proposed to perform an in situ sensitivity and position cross-calibration of the detectors with an iterative procedure, by using the information redundancy and data variability in a given set of reconstructed profiles. Finally, the basic steps to build a synthetic tomography diagnostics in a more realistic tokamak environment are introduced, together with some tools to assess the capabilities of the 2D tomography algorithm.

The system proposed to measure the tritium to deuterium ratio on the International Thermonuclear Experimental Reactor (ITER) is a high-resolution neutron spectrometer, partly composed of a system of three Thin-foil Proton Recoil (TPR) spectrometers. This system works on the principle of converting neutrons into protons using a thin foil of polyethylene, which is then detected in silicon detectors to obtain the scattering angles and energy spectrum of the protons. The objective of this article is to show the benefit of artificial intelligence for improving a simple TPR system model written in Python to an accuracy approaching MCNP simulations, while significantly decreasing the computational cost. The first step was to model a polyethylene converter to obtain the energy-angle distribution of outgoing protons for a given incident neutron beam. When compared with MCNP, this simplified model was found to fail to account for proton energy and angular scattering. Therefore, in a second step, two neural networks were successfully trained to include these effects based on the output data of the TRIM code, assuming Gaussian distributions. The Python model was able to produce results very close (differences up to a few percent) to those obtained with MCNP by integrating these neural networks. To extend the study, the energy spectra of the protons could be obtained and subsequently used to obtain information on the ratio of deuterium and tritium in the plasma.

Tomography diagnostics represent an essential tool in tokamaks to infer the local plasma properties using line-integrated measurements from one or several cameras. In particular, soft X-rays (SXR) in the energy range 0.1–20 keV can provide valuable information on magnetohydrodynamic activity, magnetic equilibrium or impurity transport. Heavy impurities like tungsten (W) are a major source of concern due to significant radiation losses in the plasma core, thus they have to be kept under acceptable concentrations. Therefore, 2D SXR tomography diagnostics become crucial to estimate the W concentration profile in the plasma, quantify the W poloidal distribution and identify relevant impurity mitigation strategies. In this context, a synthetic diagnostic becomes a very valuable tool (1) to study the tomographic reconstruction capabilities, (2) to validate diagnostic design as well as (3) to assess the error propagation during the reconstruction process and impurity transport analysis. The goal of this contribution is to give some highlights on recent studies related to each of these three steps, for the development of SXR synthetic diagnostic tools in tokamak plasmas.

Bayesian inference is used in many scientific areas as a conceptually well-founded data analysis framework. In this paper, we give a brief introduction to Bayesian probability theory and its application to the tomography problem in fusion research by means of a Gaussian process prior. This Gaussian process tomography (GPT) method is used for reconstruction of the local soft X-ray (SXR) emissivity in WEST and EAST based on line-integrated data. By modeling the SXR emissivity field in a poloidal cross-section as a Gaussian process, Bayesian SXR tomography can be carried out in a robust and extremely fast way. Owing to the short execution time of the algorithm, GPT is an important candidate for providing real-time feedback information on impurity transport and for fast MHD control. In addition, the Bayesian formulism allows for uncertainty analysis of the inferred emissivity.

Data quality of the tokamaks diagnostics is often a neglected topic. In literature it is rather rare to find considerations regarding the data quality received from the diagnostic systems’ sensors. The scope of the paper is to provide a discussion regarding systems’ construction and analysis in scope of implementation of data quality monitoring methods for a new generation of diagnostics. Mainly considerations are performed regarding the necessity of DQM (Data Quality Monitoring) implementation, functionality, performance and required system resources. The covered topics are related to basics of system construction including: system layout and construction blocks, data processing stages, signal processing modes, system construction with resource estimation in scope of DQM implementation. Based on the covered points, it is possible to plan the extra resources or specific construction, to provide reliable design with data quality monitoring features. The data quality monitoring aspect is especially important in the modern diagnostics working with a real-time feedback loop. Such approach could be especially interesting for the ITER-like projects, since the quality of the data may directly influence the behavior of the control systems during plasma phenomena. The work is based on experience in design work of various high performance diagnostic systems for plasma physics and high energy physics.

A multi-machine study has been carried out to investigate the impact of a strongly bounded wave propagation domain on the Lower Hybrid current drive, a condition which occurs principally in high aspect ratio tokamaks. In this regime, the condition of kinetic resonance can be far above the upper boundary of the propagation domain, and may not be achieved by the usual toroidal upshift. Therefore no tail of fast electrons can be pulled out from the thermal bulk. Nevertheless, while tokamak plasmas are in principle almost transparent to the wave in this regime so-called “unbridgeable spectral gap”, full current drive is well achieved for the two tokamaks considered in this study, TRIAM-1M (Zushi et al. Nucl Fusion 43:1600, 2003) and WEST (Bourdelle et al. Nucl Fusion 55:063017, 2015), both characterized by a very large aspect ratio R / a > 5.5 . The case of the high aspect ratio tokamak HL-2A (Liu et al. Nucl Fusion 45:S239, 2005) for which the wave propagation domain has also an upper boundary, but close to the resonance condition, is considered by comparison. First principles modeling of the rf-driven current and the fast electron bremsstrahlung using the ALOHA/C3PO/LUKE/R5-X2 chain of codes shows unambiguously that the spectral gap must be already filled at the separatrix in order to reproduce quantitatively observations and some important parametric dependencies. This result is an important milestone in the physics understanding of the Lower Hybrid current drive, highlighting the existence of a powerful and likely universal alternative mechanism to bridge the spectral gap, that is not related to toroidal magnetic refraction. With an initially broad power spectrum, lobes with low parallel refractive indexes that carry most of the plasma current can be absorbed in almost single pass, restoring the full validity of the ray-tracing approximation for describing the propagation of the Lower Hybrid wave in cold plasmas.

A new family of techniques, called conformal predictors, have very recently been developed to hedge the estimates of machine learning methods, by providing two parameters, credibility and confidence, which can assess the level of trust that can be attributed to their outputs. In this paper, the main steps required to extend this approach to fuzzy logic classifiers are reported. The more delicate aspect is the definition of an appropriate nonconformity score, which has to be based on the fuzzy membership function to preserve the specificities of Fuzzy Logic. Various examples of increasing complexity are introduced, to describe the main properties of fuzzy logic based conformal predictors and to compare their performance with alternative approaches. The obtained results are quite promising, since conformal predictors based on fuzzy classifiers outperform solutions based on the nearest neighbour in terms of ambiguity, robustness and interpretability.

This contribution reviews an important example of current developments in diagnostic systems and data analysis tools aimed at improved understanding and control of transport processes in magnetically confined high temperature plasmas. The choice of tungsten for the plasma facing components of ITER and probably also DEMO means that impurity control in fusion plasmas is now a crucial challenge. Soft X-ray (SXR) diagnostic systems serve as a key sensor for experimental studies of plasma impurity transport with a clear prospective of its control via actuators based mainly on plasma heating systems. The SXR diagnostic systems typically feature high temporal resolution but limited spatial resolution due to access restrictions. In order to reconstruct the spatial distribution of the SXR radiation from line integrated measurements, appropriate tomographic methods have been developed and validated, while novel numerical methods relevant for real-time control have been proposed. Furthermore, in order to identify the main contributors to the SXR plasma radiation, at least partial control over the spectral sensitivity range of the detectors would be beneficial, which motivates for developments of novel SXR diagnostic methods. Last, but not least, semiconductor photosensitive elements cannot survive in harsh conditions of future fusion reactors due to radiation damage, which calls for development of radiation hard SXR detectors. Present research in this field is exemplified on recent results from tokamaks COMPASS, TORE SUPRA and the Joint European Torus JET. Further planning is outlined.

Flies in the order Diptera are of forensic value because many species leave tractable evidence while harvesting nutrients from decomposing corpses. From December 2015 to January 2017, 41 fly specimens were collected in human bodies at crime scenes and autopsies across the south of Ecuador. Six species, e.g., Chrysomya albiceps (Widemann 1819), Chrysomya megacephala (Fabricius, 1794), Synthesiomyia nudiseta (Wulp, 1883), Lucilia purpurascens (Walker, 1836), Hemilucilia segmentaria (Fabricius, 1805), and Stomoxys calcitrans (Linneo, 1758) were identified to species level using morphological (dichotomous keys) and molecular (mitochondrial COI barcodes) techniques. One additional specimen remains unidentified to species level, but COI barcodes assigned it to the genus Paralucilia. These first taxonomically curated records of flies in real cases constitute a tangible groundwork for the development of forensic entomology in Ecuador.

Abstract In order to contribute to the comprehension of the current situation of organic markets, this research investigates a prominent case at Florianopolis: Cantinho Especial Market. The methodology employed in this study involved six months of analysis of the market's institutional website (fan page) in a social network, eight months of unsystematic observations at the market and nine interviews with agents both from supply and demand. We argue here that recurrent categories used in sociological research on organic markets, such as political consumerism and ecological ethics, are sparser among this market participant agents. Instead of these recurrent categories, we realize that organics are in the display window acting as decoys to a distinctive symbolic exchanges market. These symbolic trades when combined together reflect a lifestyle marked by the praise of the exoticism and the cosmopolitanism. Resumen Tratando de contribuir a la comprensión de la situación actual del mercado de alimentos orgánicos, este trabajo investiga un caso destacado en Florianópolis: Cantinho Especial Market. La metodología incluyó seis meses del análisis de la página de fans en una red social, ocho meses de observaciones no sistemáticas y nueve entrevistas con agentes de la oferta y de la demanda. Argumentamos que categorías frecuentes en las investigaciones sociológicas sobre compra y venta de productos orgánicos, tales como el consumo político y la ética ecológica son escasas entre los agentes sociales del principal mercado especializado de la provincia de Santa Catarina. Los orgánicos están en el escaparate, actuando como señuelos para un mercado más amplio de intercambios simbólicos distintivos. Estos, cuando se combinan juntos, pueden ser identificados como un estilo de vida caracterizado por la alabanza del exotismo y del cosmopolitismo. Resumo Como forma de contribuir para a compreensão do atual momento do mercado de orgânicos, o presente trabalho investiga um caso proeminente em Florianópolis: o Mercado Cantinho Especial. A metodologia empregada no presente estudo envolveu seis meses de análise da página institucional (fan page) do dito mercado em uma rede social, assim como oito meses de observações assistemáticas em seu interior e nove entrevistas com agentes da oferta e da demanda. Argumenta-se aqui que categorias de análise recorrentes em pesquisas sociológicas sobre espaços de compra e venda de orgânicos, tais como o consumo político e a ética ecológica, são rarefeitas entre os agentes sociais do principal mercado especializado da capital catarinense. Contudo, percebe-se que os orgânicos estão na vitrine, atuando como chamariz em um mercado de trocas simbólicas distintivas mais amplas. Tais trocas, quando reunidas em conjunto, podem ser identificadas como um estilo de vida marcado pelo elogio ao exotismo e ao cosmopolitismo.