Tungsten divertor sources in WEST related to impurity inventory and local plasma conditions

A dedicated series of L-mode deuterium discharges were performed in WEST in which a broad parameter space in terms of divertor plasma temperature (inner divertor at &lt;10 eV, outer divertor up to 50 eV) and impurity flux density was achieved by variation of X point elevation, upstream plasma density and fuelling position and rate. Density steps provided stable reference plasma conditions whilst density scans up to the point of detachment revealed the sputtering threshold behaviour of the dominant sputtering species. Tungsten gross erosion was quantified via the common WI 400.9 nm line and correlated with the residual gas content.</p

Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

We describe a new technique for the efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed ‘three-ion’ scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of the method on the world-largest plasma magnetic confinement device, JET (Joint European Torus, Culham, UK), and the high-magnetic-field tokamak Alcator C-Mod (Cambridge, USA). The obtained results demonstrate efficient acceleration of 3He ions to high energies in dedicated hydrogen–deuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast 3He ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space-plasma environments, in particular, 3He-rich solar flares.This paper is dedicated to the late P. E. M. Vandenplas, founder and first director of LPP-ERM/KMS, in recognition of his lifelong outstanding commitment to fusion research, in particular to ICRH. The support from the JET and Alcator C-Mod Teams is warmly acknowledged. We are grateful to A. Cardinali, C. Castaldo, R. Dumont, J. Eriksson, T. Fülöp, C. Giroud, C. Hellesen, S. Menmuir and M. Schneider for fruitful discussions. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under grant agreement no. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This work was also supported by the US DoE, Office of Science, Office of Fusion Energy Sciences, SciDAC Center for Simulation of Wave Plasma Interactions under DE-FC02-01ER54648 and the User Facility Alcator C-Mod under DE-FC02-99ER54512. The Alcator C-Mod Team author list is reproduced from ref. 12. The JET Contributors author list is reproduced from ref. 33.Peer ReviewedPostprint (author's final draft

BMJ Open

INTRODUCTION: Sarcomas are rare tumours of connective tissue. The exact overall incidence of sarcomas is unknown due to diagnostic difficulties and the various histological subtypes (over 80 subtypes). However, the apparent increasing incidence of sarcomas suggests environmental causes such as pesticides. Except for some specific factors (ie, ionising radiation, vinyl chloride, dioxin and genetic predispositions) the scientific knowledge on the aetiology of sarcomas is sparse and inconsistent. France is a particularly appropriate country to set up a study investigating the causes of sarcoma occurrence due to the French organisation in treatment and care of sarcoma patients, which is highly structured and revolved around national expert networks. The main objective of the ETIOlogy of SARcomas (ETIOSARC) project is to study the role of lifestyle, environmental and occupational factors in the occurrence of sarcomas among adults from a multicentric population-based case-control study. METHODS AND ANALYSIS: Cases will be all incident patients (older than 18 years) prospectively identified in 15 districts of France covered by a general population-based cancer registry and/or a reference centre in sarcoma's patient care over a 3-year period with an inclusion start date ranging from February 2019 to January 2020 and histologically confirmed by a second review of the diagnosis. Two controls will be individually matched by sex, age (5 years group) and districts of residence and randomly selected from electoral rolls. A standardised questionnaire will be administered by a trained interviewer in order to gather information about occupational and residential history, demographic and socioeconomic characteristics and lifestyle factors. At the end of the interview, a saliva sample will be systematically proposed. This study will permit to validate or identify already suspected risk factors for sarcomas such as phenoxyherbicides, chlorophenol and to generate new hypothesis to increase our understanding about the genetic and environmental contributions in the carcinogenicity process. ETHICS AND DISSEMINATION: The present study is promoted by the French National Institute of Health and Medical Research (identification number C17-03). This study received National French Ethic committee (CPP Sud Mediterrannee I) approval (identification number 18-31) and French Data Protection Authority (CNIL) approval (identification number 918171). Results of this study will be published in international peer-reviewed journals. Technical appendix, statistical code and dataset will be available in the Dryad repository when collection data are completed. TRIAL REGISTRATION NUMBER: NCT03670927

Representing 3D Space in Working Memory: Spatial Images from Vision, Hearing, Touch, and Language

The chapter deals with a form of transient spatial representation referred to as a spatial image. Like a percept, it is externalized, scaled to the environment, and can appear in any direction about the observer. It transcends the concept of modality, as it can be based on inputs from the three spatial senses, from language, and from long-term memory. Evidence is presented that supports each of the claimed properties of the spatial image, showing that it is quite different from a visual image. Much of the evidence presented is based on spatial updating. A major concern is whether spatial images from different input modalities are functionally equivalent— that once instantiated in working memory, the spatial images from different modalities have the same functional characteristics with respect to subsequent processing, such as that involved in spatial updating. Going further, the research provides some evidence that spatial images are amodal (i.e., do not retain modality-specific features)

Operating a full tungsten actively cooled tokamak: overview of WEST first phase of operation

WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up to 1000 s. In support of ITER operation and DEMO conceptual activities, key missions of WEST are: (i) qualification of high heat flux plasma-facing components in integrating both technological and physics aspects in relevant heat and particle exhaust conditions, particularly for the tungsten monoblocks foreseen in ITER divertor; (ii) integrated steady-state operation at high confinement, with a focus on power exhaust issues. During the phase 1 of operation (2017–2020), a set of actively cooled ITER-grade plasma facing unit prototypes was integrated into the inertially cooled W coated startup lower divertor. Up to 8.8 MW of RF power has been coupled to the plasma and divertor heat flux of up to 6 MW m−2 were reached. Long pulse operation was started, using the upper actively cooled divertor, with a discharge of about 1 min achieved. This paper gives an overview of the results achieved in phase 1. Perspectives for phase 2, operating with the full capability of the device with the complete ITER-grade actively cooled lower divertor, are also described

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

Shattered pellet injection experiments at JET in support of the ITER disruption mitigation system design

A series of experiments have been executed at JET to assess the efficacy of the newly installed shattered pellet injection (SPI) system in mitigating the effects of disruptions. Issues, important for the ITER disruption mitigation system, such as thermal load mitigation, avoidance of runaway electron (RE) formation, radiation asymmetries during thermal quench mitigation, electromagnetic load control and RE energy dissipation have been addressed over a large parameter range. The efficiency of the mitigation has been examined for the various SPI injection strategies. The paper summarises the results from these JET SPI experiments and discusses their implications for the ITER disruption mitigation scheme