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Hot Vertical-Displacement-Event Process due to Internal Energy Perturbations for HL-2M Tokamak Plasma

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Chinese Physics Letters 2016年第5期33卷 58-62页

作者：薛雷段旭如郑国尧刘钺强晏石磊 V.N.Dokuka V.E.Lukash R.R.Khayrutdinov Southwestern Institute of Physics ccfe Culham Science Centre TRINITI NRC Kurchatov Institute National Research Nuclear University MEPhI Moscow Engineering Physics Institute

During the tokamak operation, variation of the stored energy can cause internal perturbations of the plasma. These perturbations may develop into large-scale vertical movement of the whole column for the vertically elon- gated tokamak, eventually generating the hot vertical displacement event （VIDE,）. It will cause considerable damage to the machine. In this work, the hot VDE process due to stored energy perturbations is investigated by a mature non-linear time-evolution code DINA. The influence on the vertical instability, the displacement direction and the electromagnetic loads on in-vessel components during the hot VDE are analyzed. It is shown that a larger perturbation leads to faster development of the vertical instability. Meanwhile the variation of the Shafranov shift, due to the energy change, is related to the VDE direction. The vertical electromagnetic force on the vacuum vessel and the halo current flowing in the divertor baffle become larger in the case of VDE moving towards the X point.

关键词： of on as in Hot Vertical-Displacement-Event Process due to Internal Energy Perturbations for HL-2M Tokamak Plasma for is line that HL

Investigating the physics of disruptions with real-time tomography at JET

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Plasma Science and Technology 2022年第3期24卷 80-88页

作者： Diogo R FERREIRA Pedro J CARVALHO Ivo S CARVALHO Chris I STUART Peter J LOMAS JET Contributors 无 Instituto de Plasmas e Fusão Nuclear(IPFN) Instituto Superior Técnico(IST)Universidade de LisboaAv.Rovisco Pais 11049-001 LisboaPortugal Culham Centre for Fusion Energy(ccfe) UK Atomic Energy Authority(UKAEA)Culham Science CentreAbingdonOX143DB OxfordshireUnited Kingdom See the author list of E.Joffrin et al 2019 Nucl Fusion 59112021 EUROfusion Consortium JETCulham Science CentreAbingdonOX143DBUK

As JET is developing and testing operational scenarios for higher fusion performance,an increase in pulse disruptivity is being *** a deeper analysis,we find that several radiative phenomena play an active role in determining the outcome of the *** analysis is enabled by the use of real-time tomography based on the bolometer *** though plasma tomography is an inverse problem,we use machine learning to train a forward model that provides the radiation profile directly,based on a single matrix multiplication *** model is used to investigate radiative phenomena including sawtooth crashes,ELMs and MARFE,and their relationship to the radiated power in different regions of *** particular,we use realtime tomography to monitor the core region,and to throw an alarm whenever core radiation exceeds a certain *** results suggest that this measure alone can anticipate a significant fraction of disruptions in the JET baseline scenario.

关键词： plasma tomography machine learning plasma disruptions

In situ neutron diffraction unravels deformation mechanisms of a strong and ductile Fe Cr Ni medium entropy alloy

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Journal of Materials Science & Technology 2022年第21期116卷 103-120页

作者： L.Tang F.Q.Jiang J.S.Wróbel B.Liu S.Kabra R.X.Duan J.H.Luan Z.B.Jiao M.M.Attallah D.Nguyen-Manh B.Cai School of Metallurgy and Materials University of BirminghamB152TTUnited Kingdom Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Faculty of Materials Science and Engineering Warsaw University of Technologyul.Wołoska 141Warsaw 02-507Poland State Key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China Rutherford Appleton Laboratory ISIS FacilityDidcot OX110QXUnited Kingdom Department of Materials Science and Engineering City University of Hong KongKowloonHong KongChina Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina ccfe United Kingdom Atomic Energy AuthorityAbingdonOxfordshire OX143DBUnited Kingdom

We investigated the mechanical and microstructural responses of a high-strength equal-molar medium entropy FeCrNi alloy at 293 and 15 K by in situ neutron diffraction *** 293 K,the alloy had a very high yield strength of 651±12 MPa,with a total elongation of 48%±5%.At 15 K,the yield strength increased to 1092±22 MPa,but the total elongation dropped to 18%±1%.Via analyzing the neutron diffraction data,we determined the lattice strain evolution,single-crystal elastic constants,stacking fault probability,and estimated stacking fault energy of the alloy at both temperatures,which are the critical parameters to feed into and compare against our first-principles calculations and dislocation-based slip system *** density functional theory calculations show that the alloy tends to form shortrange order at room ***,atom probe tomography and atomic-resolution transmission electron microscopy did not clearly identify the short-range ***,at 293 K,experimental measured single-crystal elastic constants did not agree with those determined by first-principles calculations with short-range order but agreed well with the values from the calculation with the disordered configuration at 2000 *** suggests that the alloy is at a metastable state resulted from the fabrication *** view of the high yield strength of the alloy,we calculated the strengthening contribution to the yield strength from grain boundaries,dislocations,and lattice *** lattice distortion contribution was based on the Varenne-Luque-Curtine strengthening theory for multi-component alloys,which was found to be 316 MPa at 293 K and increased to 629 MPa at 15 K,making a significant contribution to the high yield *** plastic deformation,dislocation movement and multiplication were found to be the dominant hardening mechanism at both temperatures,whereas twinning and phase transformation were not *** is mainly due to the high stack

关键词： Medium entropy alloy Multi-component alloy Cryogenic temperature Neutron diffraction

A systematic investigation of radiation collapse for disruption avoidance and prevention on JET tokamak

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Matter and Radiation at Extremes 2023年第4期8卷 55-75页

作者： R.Rossi M.Gelfusa T.Craciunescu L.Spolladore I.Wyss E.Peluso J.Vega C.F.Maggi J.Mailloux M.Maslov A.Murari on behalf of JET Contributors Department of Industrial Engineering University of Rome“Tor Vergata”via del Politecnico 1RomaItaly National Institute for Laser Plasma and Radiation PhysicsMagurele-BucharestRomania Laboratorio Nacional de Fusión CIEMATAv.Complutense 4028040 MadridSpain UKAEA-ccfe Culham Science CentreAbingdon OX143DBUnited Kingdom Consorzio RFX(CNR ENEAINFNUniversitàdi PadovaAcciaierie Venete SpA)Corso Stati Uniti 435127 PadovaItaly Istituto per la Scienza e la Tecnologia dei Plasmi CNRPadovaItaly EUROfusion Consortium JETCulham Science CentreAbingdon OX143DBUnited Kingdom

To produce fusion reactions efficiently,thermonuclear plasmas have to reach extremely high temperatures,which is incompatible with their coming into contact with material *** of plasmas using magnetic fields has progressed significantly in the last years,particularly in the tokamak ***,all tokamak devices,and particularly metallic ones,are plagued by catastrophic events called *** disruptions are preceded by anomalies in the radiation patterns,particularly in ITER-relevant *** specific forms of radiation emission either directly cause or reveal the approaching collapse of the *** the localization of these radiation anomalies in real time requires an innovative and specific elaboration of bolometric measurements,confirmed by visible cameras and the inversion of sophisticated tomographic *** information derived from these measurements can be interpreted in terms of local power balances,which suggest a new quantity,the radiated power divided by the plasma internal energy,to determine the criticality of the plasma *** with robust indicators of the temperature profile shape,the identified anomalous radiation patterns allow determination of the sequence of macroscopic events leading to disruptions.A systematic analysis of JET campaigns at high power in deuterium,full tritium,and DT,for a total of almost 2000 discharges,proves the effectiveness of the *** warning times are such that,depending on the radiation anomaly and the available actuators,the control system of future devices is expected to provide enough notice to enable deployment of effective prevention and avoidance strategies.

关键词： tokamak prevention approaching