Modelling of PFC Life-Time in Tokamak Fusion Reactor (KIT Scientific Reports ; 7612)

The performance of materials in fusion reactor DEMO has long been recognized as fundamental issue affecting the ultimate technological and economic feasibility of fusion power. Many factors influence the choice of a functional and structural material in a fusion reactor. Three effects limit component lifetime in the steady-state operation: radiation damage, disruptions, and sputtering erosion. Our design strategy is to determine the structure and coating thickness, which maximize component life

Design Strategy for the PFC in DEMO Reactor (KIT Scientific Reports ; 7637)

The performance of the plasma facing components (PFC) and materials in fusion reactor DEMO are fundamental issues affecting the ultimate technological and economic feasibility of fusion power. Many factors influence the choice of a functional and structural material in a fusion reactor. Component lifetime is mainly limited by radiation damage, disruptions, and sputtering erosion. Our design strategy is to determine the structure and coating thicknesses, which maximize component lifetime against all life limitations

Modeling of tungsten melt layer erosion caused by JxB force at TEXTOR with the code MEMOS

Tungsten in form of macrobrush is foreseen as one of candidate materials for the ITER divertor. Melting of tungsten, the melt motion, and melt splashing are expected to be the main mechanisms of a surface damage determining the lifetime of plasma facing components. Experiments with the long-time plasma action at the metalic surface in a strong magnetic field demonstrated that the JxB force generated by the thermo-emission electrons dominates in the acceleration of the melt layer and leads to a high target damage. In the paper numerical simulation model implemented into the code MEMOS is described and modelling of tungsten target damage caused by the long-time plasma heat loads supporting the TEXTOR experiments are performed with 3D version of the code MEMOS. Calculated damages of tungsten targets are in a reasonable agreement with the target damages observed in the TEXTOR experiments that allows projections upon the surface damage at ITER and DEMO conditions.Вольфрам в виде макробрашей рассматривается в качестве основного материала для дивертора ИТЭРа. Плавления вольфрама, движение и разбрызгивание расплава рассматриваются в качестве основных механизмов повреждения поверхности, которые определяют время жизни элементов дивертора. Эксперименты с длительным воздействием плазмы на металлические поверхности в сильном магнитном поле показали, что JxB-сила, генерируемая термоэмиссией электронов, доминирует в ускорении слоя расплава и приводит к большому повреждению поверхности. Описана численная модель моделирования эрозии металлической поверхности при плазменном воздействии, имплементированная в код MEMOS. Приведены результаты моделирования эрозии вольфрамовой мишени, вызванной длительным воздействием плазмы в экспериментах в TEXTORе, проведенного 3D-версией кода MEMOS. Расчетная эрозия вольфрама находится в разумном согласии с эрозией вольфрамового лимитера, которая наблюдалась в экспериментах в TEXTORе. Данные расчета позволяют делать прогнозы относительно эрозии поверхности в условиях ИТЭР и ДЕМО.Вольфрам у вигляді макробрашів розглядається в якості основного матеріалу для дивертора ІТЕРа. Плавлення вольфраму, рух і розбризкування розплаву розглядаються в якості основних механізмів пошкодження поверхні, що визначають час життя елементів дивертора. Експерименти з тривалим впливом плазми на металеві поверхні в сильному магнітному полі показали, що JxB-сила, що генерується термоемісією електронів, домінується в прискоренні шару розплаву і приводить до великих пошкоджень поверхні. Описана чисельна модель моделювання ерозії металевої поверхні при плазмовому впливі, імплементована в код MEMOS. Наведено результати моделювання ерозії вольфрамової мішені, викликаної тривалим впливом плазми в експериментах в TEXTORі, проведенного 3D-версією коду MEMOS. Розрахункована ерозія вольфраму знаходиться в розумній згоді з ерозією вольфрамового лімітера, яка спостерігалася в експериментах в TEXTORі. Дані розрахунку дозволяють робити прогнози, щодо ерозії поверхні в умовах ІТЕР і ДЕМО

Simulation of Be armour cracking under ITER-like transient heat loads

Simulation of beryllium cracking under action of multiple severe surface heatings has been performed using the PEGASUS-3D code and verified by experiments in the JUDITH 1 facility. Analysis of the results has revealed beryllium thermo conductivity degradation under action of repetitive pulsed heat load due to accumulation of the cracks in the surface layer. Thermo conductivity degradation is found to be at least 4 times after 100 pulses in JUDITH 1 facility. An analytical model for the Be cracking threshold under action of arbitrary heat pulses has been developed

Effect of design geometry of the demo first wall on the plasma heat load

In this work we analyse the effect of W armour surface shaping on the heat load on the W/EUROFER DEMO sandwich type first wall blanket module with the water coolant. The armour wetted area is varied by changing the inclination and height of the «roof» type armor surface. The deleterious effect of leading edge at the tiles corner caused by misalignment is replaced in current design by rounded corners. Analysis has been carried out by means of the MEMOS code to assess the influence of the thickness of the layers and effect of the magnetic field inclination. Calculations show the evolution of the maximum temperatures in the tungsten, EUROFER, Cu allow and the stainless-steel water tube for different level of surface inclination (chamfering) and in the case of rounded corners used in the current design. It is shown that the blanket module materials remain within a proper temperature range only at shallow incident angle if the width of EUROFER is reduced at list twice compare with the reference case

Two-stage evolution of mantle peridotites from the Stalemate Fracture Zone, northwestern Pacific

This paper reports the results of a mineralogical study of 14 mantle peridotite samples dredged in 2009 from the eastern slope of the northwestern segment of the Stalemate Ridge in the northwestern Pacific during cruise SO201-KALMAR Leg 1b of the R/V Sonne. The sample collection included four serpentinized and silicified dunites and ten variably serpentinized lherzolites. The compositions of primary minerals (clinopyroxene, orthopyroxene, and spinel) change systematically from the lherzolites to dunites. Spinel from the lherzolites shows higher Mg# and lower Cr# values (0.65-0.68 and 0.26-0.33, respectively) compared with spinel from the dunites (Mg# = 0.56-0.64 and Cr# = 0.38-0.43). Clinopyroxene from the lherzolites is less magnesian (Mg# = 91.7-92.4) than clinopyroxene from dunite sample DR37-3 (Mg# = 93.7). Based on the obtained data, it was concluded that the lherzolites of the Stalemate Fracture Zone were derived by 10-12% near-fractional melting of a DMM-type depleted mantle reservoir beneath the Kula-Pacific spreading center. The dunites were produced by interaction of residual lherzolites with sodium- and titaniumrich melt and are probably fragments of a network of dunite channels in the shallow mantle. The moderately depleted composition of minerals clearly distinguishes the lherzolites from the strongly depleted peridotites of the East Pacific Rise and indicates the existence of slow-spreading mid-ocean ridges in the Pacific Ocean during the Cretaceous-Paleogene