Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

Sporadic Creutzfeldt-Jakob disease mimicking nonconvulsive status epilepticus.

International audienceBACKGROUND: Nonconvulsive status epilepticus (NCSE) in patients with confusion may be difficult to distinguish from nonepileptic (metabolic/toxic, postanoxic, and spongiform) encephalopathies. This study aimed to describe the misleading presentation of patients with sporadic Creutzfeldt-Jakob disease (sCJD) who were initially diagnosed with a refractory NCSE (rNCSE). METHODS: We retrospectively reviewed the clinical characteristics, EEG records, brain MRI scans, 14-3-3 protein detection in CSF, genotype of the prion protein gene, and neuropathologic data of patients referred to our neurologic intensive care unit (NICU) with this presentation. RESULTS: Ten patients with a final diagnosis of definite (n = 7) or probable (n = 3) sCJD were referred to our NICU with an initial diagnosis of rNCSE. Reanalysis of the EEG ruled out ictal rhythmic activities, but showed diffuse, periodic, or semiperiodic sharp-wave complexes (PSWC) with short period. PSWC were briefly attenuated by auditory (n = 5) or painful (n = 3) stimuli and by IV injection of antiepileptic drugs (n = 5) but without clinical improvement. In addition, PSWC showed fluctuations according to the vigilance level (n = 5). Brain MRI showed hyperintensities in basal ganglia (n = 9/10) and in cortical areas (n = 7/10). 14-3-3 Protein was detected in CSF (n = 10). Only 2 sCJD subtypes were found (MM1 5/7, MV1 2/7). CONCLUSIONS: This series of patients suggests that sporadic Creutzfeldt-Jakob disease should be considered as a differential diagnosis, rather than as a cause, of apparent refractory nonconvulsive status epilepticus. Criteria for nonconvulsive status epilepticus diagnosis should rely on careful examination of both EEG parameters and clinical state so that aggressive, unnecessary treatments can be avoided