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- Joffrin, E., et al.
(author)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Research review (peer-reviewed)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 3. |
- Elias, Augusto E., et al.
(author)
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MR Spectroscopy Using Normalized and Non-normalized Metabolite Ratios for Differentiating Recurrent Brain Tumor from Radiation Injury
- 2011
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In: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 18:9, s. 1101-1108
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Journal article (peer-reviewed)abstract
- Rationale and Objectives: To compare the ability of normalized versus non-normalized metabolite ratios to differentiate recurrent brain tumor from radiation injury using magnetic resonance spectroscopy (MRS) in previously treated patients. Materials and Methods: Twenty-five patients with previous diagnosis of primary intracranial neoplasm confirmed with biopsy/resection, previously treated with radiation therapy (range, 54-70 Gy) with or without chemotherapy and new contrast enhancing lesion on a 1.5 T magnetic resonance imaging at the site of the primary neoplasm participated in this retrospective study. After MRS, clinical, radiological, and histopathology data were used to classify new contrast-enhancing lesions as either recurrent neoplasm or radiation injury. Volume of interest included both the lesion and normal-appearing brain on the contralateral side. Non-normalized metabolic ratios were calculated from choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) spectroscopic values obtained within the contrast-enhancing lesion: Cho/Cr, NAA/Cr, and Cho/NAA. Normalized ratios were calculated using the metabolic values from the contralateral normal side: Cho/normal creatinine (nCr), Cho/normal N-acetylaspartate (nNAA), Cho/normal choline, NAA/nNAA, NAA/nCr, and Cr/nCr. Results were correlated with the final diagnosis by Wilcoxon rank-sum analysis. Results: Two of three non-normalized ratios, Cho/NAA (sensitivity 86%, specificity 90%) and NAA/Cr (sensitivity 93%, specificity 70%) significantly associated with tumor recurrence even after correcting for multiple comparisons. Of the six normalized ratios, only Cho/nNAA significantly correlated with tumor recurrence (sensitivity 73%, specificity 40%), but did not remain significant after correcting for multiple comparisons. Conclusion: Cho/NAA and NAA/Cr were the two ratios with the best discriminating ability and both had better discriminating ability than their corresponding normalized ratios (Area under the curve = 0.92 versus 0.77, AUC= 0.85 vs. 0.66), respectively.
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| 5. |
- Murari, A., et al.
(author)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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In: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Journal article (peer-reviewed)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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